Popular Science Monthly 1925-02: Vol 106 Iss 2

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RADIO SECTION How to build a 4-tube t to fit into your phonograph cabinet. © ei. -—~Jack Binns tells how to tune any receiver FOUNDED MONTHLY 1872 — Hints for everybody. e newest wonder of the seas—p. 35 & FEBRUARY Henry Ford’s amazing vision of the future 25 CENTS

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POPULAR SCIENCE MONTHLY SUMNER N. BLOSSOM, Editor February, 1925 | ROM the wharves at Kiel, Ger- many, the schooner Buckau re- cently put out to sea, a ship without sails or steam. Like a ghost ship it moved A Sailing Ship without Sails; New Wonder of the Seas Huge spinning cylinders harness the wind—lInventor plans to take strange vessel across the ocean this year By G. B. Seybold had provided a way for one man to operate a ship, if need be. The huge cylinders of the Buckau, he explained, were spun by a small engine, ships had relegated sailing vessels into dim obscurity, immediately challenged international attention. Several authori- ties, including officials of a great steam- ship line, pronounced the mysteriously through the water with no apparent means of propulsion. The astounded specta- tors on shore knew that the boat was an old 2000- ton steel vessel and that previously 500 square yards of canvas had been needed to propel her. But now she was denuded of all sails, masts, and rig- ging. Instead, two strange cylinders, resembling giant smoke-stacks, rose from her deck. But no smoke was pouring from them and no engine noise was heard. There was no churning of screws. Yet the ship plowed its way through the rough waters of the Baltic, and at nearly twice its former speed. OR several weeks the secret of the strange ship with the great towers was closely guarded. Peo- ple were told only that the craft was equipped with a Flettner rotor, a new invention, the work of Anton Flettner, di- rector of the Institute of Aerodynamics at Amster- dam, Holland. — When finally the ex- invention the most start- ling maritime develop- ment since Fulton’s steamboat. Others were more skeptical, asking how the Buckau would per- form in a heavy sea, and are yet to be convinced of the value of the invention. They also pointed out that the most that can be claimed for the new ship is that it will apply to better advantage the power avail- able for a ship supplied with sails. It cannot re- place, in any case, the ship driven by steam or internal - combustion en- gines. In the United States most experts have adopted - an attitude of “‘watchful waiting’? with regard to the invention. HE scientific principle upon which Doctor Flettner based his inven- tion has been known for nearly three-quarters of a century. Briefly, this is that a cylinder revolving in a current of wind will exert pressure at right angles to the current. This principle, known as the Magnus law, can be understood readily by any one who is familiar with planation came, the world source of energy. He had harnessed it in a new way. He had § developed an invention that may permit og ocean liners to reduce their crews two- thirds and save 90 per cent in fuel. He and these spinning surfaces, presented to the wind, provided a means of propulsion. This statement, after steamboats, oil- driven ships, and electrically operated © Suchen baseball. The giant cylin- gasped in amazement. For The Amazing Sailless Rotor Ship at Its Wharf ders, or rotors, spinning in Doctor Flettner calmly A mt stern-view photograph of the the two towering, spinning cylinders the wind, pecpadar igh ie recent stern-vi , 4 announced that he had Buckau at Kiel, Germany. Thein- produce 15 times as much power pressure on one side and returned to the wind as a wventor, Anton Flettner, declares that as does an equal surface of canvas suction on the other, just as the surface of a rapidly spinning baseball from the hand of a pitcher piles up a difference of pressure on its two sides that deflects the ball into a “‘curve.” In the case of the baseball, of 35

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POPULAR SCIENCE MONTHLY February, 1925 Hit SEREREEE i jitiliie A New Application of an Old Principle—the Rotor Ship and Its Inventor 1—Anton Fiettner (left), inventor of the sailless ship, with Captain Ger- hards, commander of the Buckau, on the bridge of the vessel at Hamburg Harbor, Germany. 2—The rudder and auxiliary propeller of the Buckau. The three-bladed rudder is said to enable the ship to be turned around in its own length. 3—Side view of the ship. Each of.the towering cylinders is 60 feet high and nine feet in diameter. 4—Diagrams showing operation of the revolving cylindrical masts, or rotors, in propelling the ship. The smooth surface of the cylinder, spinning in the wind, sets up increased air pressure on one side and suction on the other, driving the ship normally at right angles to the direction of the wind (see figure A). The lines in figure B indicate how air currents would be set up around the spinning cylinder, supposing there were no wind. Figure C, on the other hand, shows how the wind would pass around the cylinder, supposing it were not revolving. In neither case would there be any appreciable effect on the movement of the ship. But with the wind blowing and the cylinder spinning, the combined forces increase the pressure on one side and de- crease it on the other, as in figure D, driving the ship forward in the direction indicated by the horizontal arrow within the shaded circle course, the equivalent of wind is produced by the swift passage of the ball from pitcher to catcher. Each of the two spinning towers on the Buckau rests on a fixed pivot and moves on ball bearings. The towers are built of sheet iron about one-half an inch thick, are 60 feet high and nine feet in diameter. Two electric motors of 10 horsepower each, placed inside the pivots, drive the towers. Current for the motors is generated by a Diesel engine. The total weight of the complete mechanism— towers, engine, and motors—is about 15,000 pounds, just one-fifth the weight of the discarded sails and rigging on the same ship. In propelling a sailing boat, suction, rather than pressure, Flettner explains, is the important factor in producing motive power. His aim was to produce artificially, by means of the revolving towers, a greater suction power than that produced on the vessel equipped with sails. When wind strikes a sail, it divides equally, and in this division there results what is called a circular current. This works with the original current of wind on one side of the sail and against it on the other side. On the side where the current whirling around the sail is added to the original current, suction or pulling force is created, while on the other side the clashing of the two currents results in a pressure or pushing force. Of the two forces, suction is the greater factor in making the boat move forward. The revolving cylinders on the sailless boat impel it on exactly the same prin- ciple as sails do, but more effectively, it is claimed, because a greater suction power is produced. As the wind hits one of the rotating towers from the side, one side of the cylindrical surface naturally is moving with the wind, and the other is going against it. There is very little friction on the side where the surface goes with the wind, and much friction on the other side. The wind chooses the easier pathway, avoiding the side producing friction, and most of it goes in the direction in which the cylinder originally was traveling. Because the moving cylinder offers less resistance than a rigid sail, the wind, whirling around the cylinder, produces a much greater circular current than is created around a sail. Thus the suction is greatly increased, the inventor asserts, and the boat moves more swiftly than one with sails. (Continued on page 147) H we OH, he mi fac

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the February, 1925 POPULAR SCIENCE MONTHLY Henry Ford Says, “There Is Always Room for More” A surprising solution of traffic congestion as depicted by the maker of more than 10,000,000 automobiles—What Ford thinks about the future of ‘‘flivver’’ airplanes—How he directs the world’s most amazing industry without an office SHORT time after Dr. Hugo A Eckener had piloted the ZR-3 (Los Angeles) across the Atlantic, and had seen it stowed safely away in its hangar at Lakehurst, N. J., he visited the plants of the Ford Motor Company near Detroit, Mich. While he chatted with Henry Ford there, the conversation naturally enough veered around to aviation. “T’ve never made a flight in an air- plane,” Mr. Ford said, “‘and I don’t know that I’m particularly anxious to. I would, though, like to take a trip in a dirigible. Bring one out here some time, won’t you, Doctor Eckener, and give me a ride?” “T should be glad to, Mr. Ford,” re- plied the other; “‘but it would be impos- sible to make a landing—you have no mooring-mast.”’ “That’s right,” nodded Mr. Ford re- flectively; ‘‘we haven’t.”? He turned in- stantly to one of his engineers who hap- pened to be present. ‘“‘You might get in touch with the Navy Department to- morrow,” he suggested, ‘‘and get the specifications for a mooring-mast. We ought to have one here.” The mooring-mast is now being erected on the airplane landing-field near the Ford Experimental Laboratory at Dearborn. The First and the Ten Millionth By Raymond J. Brown I mention this incident because it illus- trates aptly, I think, not only Henry Ford’s characteristic way of doing things, but also a phase of his vast enterprises that probably is not clear in the popular mind. "THE building of that mooring-mast is not an expression of a sudden whim of Henry Ford. His wish to make a flight in a dirigible—probably uttered only half seriously—is only remotely connected with the erection of the mast, which is being put up because it has a definite, specific use to serve in the Ford organization. Dirigibles are driven by motors, and the production of motors and their development is the prime pur- pose of the Ford Motor Company. In other words, Henry Ford is only in- cidentally a manufacturer of automo- biles; his real business is the manufacture of motors. That the principal business of his company now is placing motors in automobiles is explained entirely by the fact that it is in automobiles that the motor finds its widest present-day use. Some day motors may be required in great numbers for other purposes. For that day the Ford organization even now is preparing. Here is Henry Ford, the worker of marvels, stand- ing between the first “horseless carriage” that he manufactured in 1893, and his 10 millionth auto- mobile, turned out of his factories a few months ago as he turns out a car every twelve seconds: That is why a mooring-mast for dirig- ibles is being erected at Dearborn. That is why there is already an airplane land- ing-field there. That is why you’ll find in the Ford Experimental Laboratory an all- metal speed boat, equipped with a 1000- horsepower motor, and like no other boat in the world. That is why, all about this boat, you will find automobiles, motors, and motor parts of many types and makes, constantly being studicd and tested. That is why Henry Ford has placed on the Great Lakes two motor- driven freighters that are among the largest boats that ply the waters. That is why in the offices of the experimental laboratory—the closest thing to a head- quarters that Henry Ford himself has— you will find virtually nothing that is not directly connected with motors—models of motors, plans of motors, secticnal drawings of motors, maps showing the location of the Ford iron mines, the Fcrd coal mines, the Ford forests, whence are taken the raw materials from which are to be fashioned—motors. HE Ford Motor Company has set out to know and understand what the motor will do under all circumstances, under every conceivable-condition of use; to learn, in short, what must be done to make the perfect motor for any purpose for which mankind will require it. Every- thing else in the almost unbelievably vast Ford organization is secondary. The ubiquitous Ford car is only a single form in which the idea behind the Ford enterprises takes expression. The im- mense volume of business done by the Ford Motor Company every year and the enormous profits resulting therefrom are,

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38 in a sense, only by-products: of the effort that more than 150,000 Ford employees all over the world are making to perfect the motor. Henry Ford himself made that statement to me recently at Dear- born. pyro that effort is poured a wealth of natural resources—mine products, for- est products, farm products—a wealth of technical skill, and the accumulated re- sults of the labor of many men in many diverse branches of science. These and the factories, railroad, and shipping lines, assembly plants and sales agencies, offices and laboratories, all the great enterprises that are necessary to the operation of the Ford Motor Company, Henry Ford has welded into an organization that stretches to the ends of the earth, and yet remains compact, mobile; a marvel and a miracle of efficiency. Coal and iron from the Ford mines in Kentucky, West Virginia, and Michigan, and timber from the Ford forests on the upper Michigan peninsula, are rushed in Ford ships and over the Ford railroad (the D. T. & I.) literally to be hurled into the indescribably huge Ford plants about Detroit, where they are transformed with bewildering speed into finished motor-cars and tractors that move away under their own power, or into motor-car parts boxed for shipment to the assembly plants in this country and abroad. It may give you a notion of the celerity with which things are accomplished in these Detroit plants when I say that 80 minutes after a cylinder-block casting from the Ford foundry at River Rouge— the world’s largest, by the way, where 1900 tons of iron are poured a day— enters the world- famous “Ford fac- tory” at Highland Park, it is in a freight car, a com- plete automobile power plant, tested and passed, ready to be made part of a chassis and driven away. As a stunt, for the entertain- ment of the Prince of Wales when he visited the Ford plants recently, a Ford car was com- pletely assembled in 26 minutes! Such things are made possible only by the magic of efficiency and or- ganization, exempli- fied here in three ways: First, each man— and there are about 100,000 who work in the Ford plants at Detroit—has one job to do and no more. It may be only inserting and tightening a single bolt in a cylinder head, or it may be giving the final inspection to a finished car. He does that one job, and no other; his neighbor’s job is none of his concern, nor does he attempt to make it any. Second, by an amazing and bewildering a completed car. POPULAR SCIENCE MONTHLY system of conveyors, each man’s work is brought to him, remains with him just long enough for him to complete it, and then is carried on to the man who per- forms the next step in the manufacturing process. Some jobs, of course, take more time than others, but the movements of the conveyors synchronize perfectly with the movements of the worker, who is never hurried and never left idle; his work is always before him when he is ready for it, away from him when he has finished it. The third phase of the system is the practice of completing each individual operation of manufacture in one place— making each Ford plant in effect a great number of little factories. Thus, if a part had to be cut to size, machined, painted, tipped with wood, covered with leather and crated for shipment, the various operations would not be performed in a central machine-shop, a central wood- working shop, and so on. The unit making the part would have its own machine-shop, its own paint-shop, its own boxing department. The time and labor saved by such methods, the waste and lost motion that they eliminate ex- plain in large measure why every day there issues from the Highland Park plant in finished cars and parts the equiv- alent of 7000 automobiles—one every 12 seconds or so. Probably a picture of the immensity of the results achieved by the Ford organiza- tion can be given in no better way than The Last Step in Making a Ford Car—Fitting the Body Each of the 100,000 men who work in the Ford plants at Detroit has just one definite job to do, whether it be tightening a bolt ina cylinder head or giving the final inspection to By an amazing system of conveyors, each car passes from one man to by a comparison. When, about six months ago, Henry Ford turned out his 10 millionth automobile, he had made available for the world a total of about 220,000,000 horsepower, or 76 times the potential power of Niagara Falls; 10 times the total hydroelectric power that has been developed throughout the world; the next in the process of manufacture, the movements of the conveyors synchronizing perfectly with the movements of the workers. For the entertainment of the Prince of Wales not long ago, a Ford car was completely assembled by this system in 26 minutes! February, 192g almost 25 times the total available elee tric power of the United States! And this he has done by means of g machine, which, pound for pound, jg produced more cheaply than any other similar machine in the world. A For touring-car costs 20 cents a pound, fin. ished, while a bicycle costs about a dollar, a locomotive something between 50 centg and a dollar. Ww leads, naturally enough, tog consideration of another amazing phase of the Ford way of doing things, At least three times Henry Ford has made the price of Ford cars exactly the cost of producing them. And on this basis he has sold them at a profit! Impossible? Not at all, for the profit came, not through some clever scheme of financing, but through wider application of new dis- coveries of science to manufacturing methods. Examples of the way applied science hag contributed to the lowering of Ford manufacturing costs with consequent benefit to the consumer are to be seen in every corner of the Ford factories; no where, though, on such a gigantic scale as in the marvelous plant at River Rouge, Mich., where are taken the first steps in making the products of nature into mov- ing, useful motors. I am exaggerating only slightly, for example, when I say that from the tower- ing chimneys of this huge unit in the Ford scheme there issues no smoke. Ten thousand tons of coal are burned here every 24 hours, yet there is no smoke. Why? Because certain constituents of the coal, which ordinar- ily are wasted in in- dustrial furnaces and pour forth from the chimneys as smoke, here are transformed into a variety of useful products to be used at the plant or sold outside. There are, for in- stance, 55,000 pounds of ammo nium sulphate, a valuable _ fertilizer, produced here daily; 17,000 gallons of benzol, an efficient motor fuel; 22,000 gallons of tar, useful in road construction or for other pur- poses; 12,000,000 cubic feet of gas, of which 2,000,000 are sold to the City of Detroit; light oil also — all products derived from what is usually the waste of coal, and without harming the effi- ciency of the coal as fuel, for there remains carbon in the form of coke to be used in the blast furnaces and sold to employees that their domestic fuel bills may be reduced. Carbon-monoxide gas, waste product of the blast furnaces, is piped to the power house, to be burned with the pulverized coal used there, with a consequent ine = i. eo

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uary, 192g able eleg sans of ound, ig ny other A Ford und, fin ; a dollar, | 50 cents ugh, toa amazing g things, has made 1e cost of basis he possible? ime, not inancing, new dis- facturing “ience has of Ford nsequent ye seen in ries; no ntic scale er Rouge, t steps in nto mov- htly, for he tower- the Ford ce. Ten ned here o smoke, nts of the 1 ordinar- ted in in- furnaces orth from neys as ere are d into a f useful > be used it or sold e, for in- , 55,000 ' ammo City of light oil products om what che waste 1 without the effi- ne coal as the form furnaces domestic product he power ulverized yuent ine

February, 1925 crease in the thermal efficiency of the latter. About 250 tons of coal are burned here every day to produce 60,000 kilowatts in electric power; and only from three to five wheelbarrows of ashes result! The firing-room in this plant is as clean as the operating-room in a hospital, and the firemen and other operators dress in suits of spotless white and keep them so. Detroit, it is converted into a complete power passed, ready to be made part of a chassis and driven away. This view in the Highland Park plant shows the machinery that handles These must be exactly alike in order to fit any Ford car castings. HERE is a cement mill, too, where the slag from the iron ore—wasted ordinarily—is utilized in the manufacture of 3500 barrels of cement a day. If you know of the dust and dirt that usually accompany the manufacture of cement, you will be astonished at this mill, for everything about it is as clean, almost, as the firing-room just spoken of. There was a time when it was not, how- ever. That was when the mill was new— before Henry Ford had seen it in opera- tion. After his first inspection, though, he did something that was quite unusual for him—he issued the following per- -.emptory order: “Tf that cement mill can’t be kept clean,”’ he said in effect, “close it up!”

POPULAR SCIENCE MONTHLY 39 So, of course, the cement miji was kept clean thenceforth. Everything that Henry Ford wishes done is done in just that way in the Ford organization, for he is not merely the founder of the Ford Motor Company and its nominal head, but the actual, active director of all its varying activities, its mainspring, the source of virtually all the ideas, innovations, and spectacular accomplishments that have these happen to supply the most con- venient rest. Rarely does he issue an order as an order. He merely talks the thing over with one of his lieutenants in the calmest. most detached manner im- aginable. Eventually the other grasps the idea in full detail; then it is put into effect, automatically almost. It may bea matter of manufacturing or merchandis- ing policy that involves millions of dol- From Castings to Auto Engines Eighty minutes after a cylinder-block casting from the foundry at River Rouge enters the famous Ford factory at Highland Park,

machined in a day. made the company remarkable since its inception. In fact, the most amazing thing about the more than amaz- ing Ford Motor Com- pany undoubtedly is Henry Ford himself. Here is a man, head of one of the vastest manufactur- ing enterprises ever launched, generally believed to be the richest man in the world; possibly the richest man of all time; yet he has no office—none that he occupies regularly, at any rate. When he requires a desk to work at, he goes to his experimental laboratory at Dearborn, one of the least pretentious of his plants, and sits down at any desk, any table, or any drafting-board that happens to be unoccupied. If there is no desk or table available, he is content to sit down where he can and use his knees for a desk. They tell me that he perched himself on a radi- ator recently while he chatted with the Prince of Wales. He dictates and signs his letters and checks ‘‘on the fly,’”’ wherever they hap- pen to be brought to him—against a brick wall, the hood of an automobile, or the stator of an electric generator, if any of plant, tested and Ford Plant at River Rouge—the World’s Largest In this vast plant, occupying 1100 acres, and containing 100 miles of railway track within its boundaries, the metal from the Ford mines is turned as if by magic into automobile parts. Here 1900 tons of metal are melted, molded. and Here, too, all of the Ford tractors are manufactured. The equipment is sufficient to turn out 12,000 motor blocks a day. Projected expansions will give the electric power plant a capacity of 350,000 horsepower

lars; that is his usual method of putting it into force. Perhaps it may strike you as anomalous that the man who is at the head of such a marvelous example of system and effi- ciency, where each man and each machine has only a single, definite task to perform, should himself apparently be so unsys- tematic that he does not even keep office hours. AS TO that, let us see. In tying him- self down to no settled routine, in appointing no definite place where he may be found at stated hours, Henry Ford is merely carrying out with regard to him- self the same principles of efficiency that are in force in his factories. There, re- member, each man has one job, and no more. Henry Ford, too, has one job and no more—to manage, direct, and operate the Ford Motor Company. To accomplish his job he cannot remain in one place; he must “circulate.”” That is his own word; he has used it frequently in describing the functions of an executive. He does not believe that executives should have headquarters to which the men under.them may bring’their problems for solution. He believes rather that ex- ecutives should move about emong the men, where they can be on hand when a problem arises. Consequently, all execu- tives in the Ford plants “circulate’— (Continued on page 149)

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40 POPULAR SCIENCE MONTHLY How a telephone sub- scriber hears a_mes- sage received in his absence by the auto- matic recording ma- chine. A_ cylinder record takes the mes- sage of the caller, after another record has informed him the Talks to subscriber is absent By Truman Stevens RECENTLY invented machine A performs in a way that is positively uncanny a variety of tasks ordi- narily accomplished only by human hands and brains. It will take dictation like a stenog- rapher. It will serve as secretary of a meeting or office conference. It will answer the telephone in the absence of the subscriber, report his absence to the caller, and take a message that it will repeat to the subscriber on his return. It will record perfectly a telephone conver- sation from both ends, no matter how far separated. It can be used as a dictograph in crim- February, 1925 This Automatic Secretary Callers Amazing New Office Machine Interviews Callers and Answers Phone Calls inal or other investigations. It can be hooked up toa radio receiver so that it will record automatically stock-market quotations or similar broadcast messages at the proper time. It can be put to any or all of these uses, or to any others that the ingenuity or necessity of the user may warrant, without change of mechanism. In appearance this amaz- ing apparatus resembles somewhat an old-time pho- nograph,employing cylindri- cal records, or the ordinary dictating machine to be found in many offices. Like both of these devices, the new machine re- a wax cylindrical rec- ord. Unlike them, however, the record- ing is accomplished not mechanically, but elec- trically, the sound vi- brations of the voice being transformed into electrical currents in a sort of minia- ture radio transmitter, containing a vacuum tube and a complicated series of inductances. These messages then are imprinted on the record, and are reproduced for the hearer by the usual phonographic process. Through the electrical system of recording an excellent quality of reproduction is attained, the listener hearing the true in- flection and tones of the speaker’s voice. Also it permits the use of a supersensitive microphone, which enables the user to give dictation in an ordinary conversa- tional tone from 20 feet or more away, and also causes the machine, when it is used for that purpose, to record every cords conversations on. word of a conversation in which several persons are taking part, no matter in what _parts of a room they are situated. By means of auxiliary apparatus a mag- azine of records may be installed in the machine so that when the end of one is reached, the next automatically starts re- cording, thus permitting dictation to be given or conversation of any sort to be recorded indefinitely. Each record may be shaved about 80 times before it be- comes too thin to be used further. The device may be operated for any of its many uses by either electric-lighting current or by a storage battery or dry cells, like a radio set. feral the device is employed as a telephone operator, a message suit- able for transmission to telephone callers during the absence of the subscriber is im- printed on a small auxiliary record at the left of the large wax cylinder. When a caller obtains the subscriber’s number, in the absence of the latter, this little record is set in motion by the current operating ‘the telephone bell, and the caller hears something to the following effect: ‘This is the office of Smith & Co. There is no one here at present, but you may leave a message, or you may call again at 2.30 if you prefer.” Immediately after the delivery of this message, the machine is ready to record any message the caller may desire to give. Used as the recorder of a telephone conversation, the machine starts working automatically the instant the call is put through, and imprints on the record every word uttered by either party. Brokers and others to whom repudiation of a telephoned order by a customer might mean a large financial loss, would find permanent records of their conversa- tions of especial value. “T JNTIL I found PoPpuLAR SCIENCE MONTHLY, I rarely knew what to do with my evenings,’’ a reader re- cently wrote. ‘‘I was just plain bored. “But now, with a pipe, a pair of slippers, and POPULAR SCIENCE, I have 30 evenings of freedom from monotony at my command every month. Your magazine interests me, inspires me, and gives me a lot of valuable informa- tion. It arouses my curiosity and keeps my spirit adventurous, bucks me up when I am blue, and gives me the urge to do new and unusual things. I couldn’t get along without reading it.” WHY I READ POPULAR SCIENCE MONTHLY A Prize Contest Announcement Thousands of such enthusiastic trib- utes have been received by POPULAR SCIENCE MONTHLY from its readers. Few, however, have condensed their appreciation into such a short letter. Why don’t you try it? What do you like most about the magazine? What features hit you hardest? Why do you like them? How has the magazine helped you? Point out, if you wish, specific short- cuts and ideas in this or in any other number you have made use of. You may base your letter upon the contents of this issue or on the many numbers be returned unless accompanied by a self-addressed, stamped envelope. nue, New York City. you have read and remembered. For the best letter of not more than 250 words, we offer the following prizes: $10, first prize; $5, second prize, and $1 each for the 10 next best letters. Competition closes March 10. An- nouncement of the prize-winners will appear in the June issue. A Board of Editors will be judges of the contest. Contributions to this contest cannot Address The Editor, POPULAR SCIENCE MONTHLY, 250 Fourth Ave-

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1925 veral what mag- 1 the ne ig is re- 0 be (0 be may t be- ny of hting r dry as a : suit- allers is im- it the hen a er, in ‘ecord rating hears There | may ain at of this record ) give. phone orking is put record party. liation stomer would versa- February, 1925 POPULAR SCIENCE MONTHLY HILE America’s new sky levia- thans, the Los Angeles and the Shenandoah, have been amazing the world with their successful performances, England has been testing out its first winged superdreadnaught of the air—a deadly new coast-defense air- craft, said to be the largest sin- gle-engined airplane inthe world. This mammoth machine, known as the “Cubaroo” Blackburn- Napier, recently completed a successful test flight near Hull, England. Driven by a huge 16-cylinder Napier motor of 1000 horse- power, it can carry and launch from the air at a battleship a full-sized naval torpedo Sky Superdreadnaught to Guard England weighing 1000 pounds. Its armament also includes great armor-piercing bombs, as well as machine guns for repelling air attacks. Our artist has pictured above how this tremendous fighting machine might appear in action. The small photograph shows its vast size compared with a group of men who have found shelter beneath its enormous wing. . The plane is 54 feet long, 20 feet high, and its wing span is 88 feet.

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PICTURE TO oe lim TRANSMITTED CAMERA \ / LONDON Radio By Robert E. Martin ” ADIO transmission is too slow,” R remarked Owen D. Young, chair- j man of the board of directors of the Radio Corporation of America and the General Electric Company about a year ago. “I am tired of this dot-and- dash business. I want to see the time come when an operator will press a key and—zip! the first page of the London Times will be reproduced 11 New York.” From this suggestion has sprung what is probably the most amazing develop- ment that has come in the radio art since the beginning of broadcasting—wireless transmission of pictures more than 3000 miles across the Atlantic from England to the United States. The “zip” stage has not yet been reached. The first page of a newspaper cannot be sent over the ocean in a flash. But a photograph or other picture, or printed matter not too large in size to be accommodated by the transmitting and receiving apparatus that has been developed, can be sent across the ocean in about 20 minutes, the time it takes in ordinary radio practice to transmit 600 words by the dot-and-dash method. Seely Corporation engineers, headed by Capt. Richard H. Ranger, are responsible for this new wonder in radio, which in time may revolutionize the pres- ent system of transmitting messages. In one important particular, at least, the engineers who designed the radio pic- ture transmitting and receiving apparatus have departed from the methods used in the- past to transmit pictures through a distance. Where most previous success- ful systems have printed the received pictures only by means of light rays, in the new method of reception, not only is each picture reproduced photographi- cally, but an additional picture is inked in simultaneously by an electrically con- trolled fountain pen that moves in wavy lines in accordance with the electrical to New York. photographs were translated into electrical Photos Cross the Sea The news in pictures is flashed over thousands of miles by the latest marvel of wireless communication POPULAR SCIENCE MONTHLY ~ CARNARVON WALES How pictures traveled by radio from London In Marconi House, London, the impulses received from the transmitting station. These pen-drawn pictures, which are made visibly, were intended at first merely as a check on the photographic reception process, which takes place within a special camera. It happened, though, that the pen-and-ink pictures presented such an odd and pleasing effect that the engineers concentrated their efforts on this method of reproduction. In transmission, a photograph of the matter to be sent is made on a positive film. This is placed on a glass cylinder, and an exceedingly thin ray of light is focused on the film from within. This beam travels across the film.in the direc- tion of the length of the cylinder, and after each journey of the ray, the cylinder is revolved a minute distance. Eventu- CYLINDER ON WHICH INK “a PICTURES ARE RECORDED f ee ae “INK RESERVOIR " MAGNET ADVANCES // | PEN-ON CYLINDERS TO START NEW LENE re ~*~, RESISTANCES CONTROL INTENSITY OF CURRENT. SUPPLY The Machine that Turns Radio Waves into Pictures Here is the remarkable receiving apparatus that translates radio-photograph signals simul- taneously irito photographic negatives and pen- impulses, which were carried by wire to high power radio-transmitting apparatus at Carnar- von, Wales. There they were sent over the ocean os Ww ade & N Aioaeee February, 1925 => ATLANTIC APPROXIMATELY 3000 5 —STANDARD HIGH POWER A) TRANSMITTING Jz APPARATUS AUTOMATIC SIGNALING RELAYS ally the whole film is traversed by the light. As the ray issues from the film, it passes into a photo-electric cell. The intensity of the ray, of course, varies as it penetrates dark or light portions of the film, and these variations produce corresponding variations in the electrical impulses that issue from the photo-electric cell. Thus light waves are transformed into electrical waves, which, amplified by vacuum tubes, may be transmitted by radio. A’ THE receiving end these electrical impulses are led through an amplify- ing device to the reproducing apparatus pictured on these pages. The amplified radio waves there operate an electrically controlled lever connected with a foun- tain pen. Each pulse of current causes TUNING FORK USED IN SYNCHRONIZING SPEEDS OF TRANSMITTING AND RECEIVING MOTORS mt CAMERA (OPEN) MAKES. ....@ PHOTOGRAPH OF TRANSMITTED PICTURE WHILE INK:-PICTURE 15 BEING waelats! and-ink reproductions of the original trans- mitted pictures. Its perfection makes it pos- sible to flash pictorial news across the ether

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POPULAR SCIENCE MONTHLY February, 1925 —— ‘ y SPECIAL RADIO “AMPLIFIER | PHOTOGRAPHIC ae eee re | \ RECEIVER: 7-_— H — . S Tr --+th:y ‘ : =e, ) | | etecTRO- . —P:, MOTOR | PEN “a se STANDARD VACUUM- TUBE AMPLIFIER IN RECEIVING BUILDING A RECORDING RSHEET | ne RIVERHEAD Neca) &\ WN Oo At Riverhead, Long Island, N. Y., the radio waves were picked up by a nine-mile antenna, amplified and relayed by iand lines to New York LONG ISLAND City, where receiving apparatus translated them again into pictures the pen to leave a mark on the surface of a paper wound about a cylinder that is the same size as, and revolves syn- chronously with, the cylinder at the trans- mitting end. INCE the move- ments of the pen LAND LINES-70 MILES— > RIVERHEAD TO NEW YORK CENTRAL RADIO OFFICE BROAD ST. NY. CITY cee - aa While these line reproductions are be- ing formed, a camera installed in the re- ceiving apparatus makes a photograph of the transmitted picture. At about the same. time that pictures were crossing the At- lantic on the wings of y the correspond with the the ether, C. Francis original light waves Jenkins, of Washing- passes that passed through ton, D. C., was dem- ensity the transmitting film, onstrating publicly trates the received picture is his system of radio }, and virtually an exact du- picture transmission, nding plication of that described in stages of s that which is being trans- its development in Thus mitted. It is not an POPULAR SCIENCE ctrical exact duplicate, for MONTHLY for May, tubes, the reason that the 1923, and June, 1924. pen tracing the re- The Jenkins method ceived picture moves is based on the same ctrical in wavy lines. These scientific principles as iplify- are caused by a trans- that devised by the aratus mission method that = z a Radio Corporation, plified Captain Ranger de- Photograph of President Coolidge sent by The Same Photograph as it was received but reproduces the rically vised. Instead of wire from Cleveland, Ohio, to New York in New York by wireless from London transmitted picture foun- transmitting continu- as a photograph, not causes ously, he has included in the sending ap- as a pen-and-ink drawing. paratus a sort of trap where the electrical impulses are stored up until they reach a certain strength, at which they automatic- ally become short-circuited and discharge. The result is that the recording pen moves not in a continuous line, but in a series of In the Laboratory The laboratory apparatus used in perfecting the new radio photo system. Capt. R. H. Ranger, of the Radio Corpora- tion of America, is seen at the right placing a film on the rotating transmitter drum. Then, of course, there is the method of picture transmission over veloped a few months ago by engineers of the American Telephone & Telegraph Company and West- ern Electric Company, which wires, de- “dots” and “‘dashes.”” The wavy effect produced thereby is rather attractive and unusual. His assistant, A. J. Koenig, is seated at the left also can be adapted to radio. Descriptions of this meth- od were published in the August and October issues of last year’s POPULAR SCIENCE MONTHLY,

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POPULAR SCIENCE MONTHLY February, 1925 AIRPLANES OBSERVING HITS BATTLESHIP TEXAS. (LATER, AIRPLANES BOMBED THE WASHINGTON FROM THE AIR ) HIT BY A BIGSHELL. BELOW: SHORTLY BEFORE SINKING > Ne FROM THE I4-INCH GUNS OF THE THE $30 000,000 WASHINGTON AIRPLANE VIEW OF THE HULL | ee a BATTLESHIP TEXAS. WHOSE BIG GUNS FINALLY SENT THE WASHINGTON DOWN, NOTE ONE SHELL EXPLODING SHORT OF ITS MARK, ANOTHER CAN BE 5 SEEN BURSTING ON b THE WASHINGTON DECK The Sinking of a $30,000,000 Dreadnaught of the recent sinking of Uncle Sam’s $30,000,000 dreadnaught Washington off Cape Hatteras, after a terrific four- day bombardment by air and by sea, we have a vivid picture of a war that knows no truce: the never-ceasing rivalry be- tween offensive weapon and defensive structure. Military science tolerates the superior- ity of neither one. The moment bombs and shells can sink a ship or wreck a fort, then every expert flings himself upon the problem of defense. The minute armor defeats the hail of steel hurled against it, I: THESE spectacular photographs our military brains fly back to the prob- lem of offense. So it was with the Washington, which, by the Limitation of Armament Treaty, we were obligated to destroy. “Our chance to prove we’re right!” cried the gunnery experts and naval con- structors in unison. Who won? Even the experts cannot say. For though the great ship finally sank, her sides sieved by 14-inch shells, the story might have been different had a crew been aboard. At Jutland ships fought on and won despite shoc-holes and leaks. The human aspect of this picture must not be misunderstood. The old horror of a raking fire that turned the war-ship’s deck into a shambles no longer exists. The modern man-of-war drives into action with not a man in sight. Captain, gun- nery officer, and navigator stand in their little conning tower. Through slits in 18-inch armor they watch the battle’s progress. Through a score of telephones they direct the complex machinery of their swiftly moving ship. A direct hit from an aerial bomb would destroy this conning tower. At once the whole control would be taken up by a substitute command group in one of the heavily armored turrets. Fe go = ——_éZln wan sat om = Pt Ce AslCUelCUClCORD

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» 1925 ht horror -ship’s exists. action » gun- . their its in attle’s yhones f their om an ynning uld be group Se February, 1925 POPULAR SCIENCE MONTHLY How Fast Can YOU Think? An expert tells how to score your mental ability by useful and fascinating tests that you can try on yourself By Donald A. Laird, Ph.D. UST how bright are you? I don’t J mean, ‘‘ How much do you know?”— because there is a difference. A filled fountain pen contains more liquid than an empty hogshead, but its capacity is not the same. How is your capacity for knowledge—your native in- Dr. J. McKeen Cattell, and others in America, after long study of intelligent, dull, and superior persons, to find out what they really could do. Now try a test of completion—that is, the ability of your mind to fill out an in- completed idea. With a pen or pencil fill in the blanks in this narrative, while who have never been to college, or even to high school, can better this time. For example, the members of a medical society in a Middle Western city were given a series of tests of general mental ability, such as you are taking on these pages. The same tests also were given to the employees of a contractor who wanted to use them in selecting the telligence that you have in- ——== herited from your parents, as opposed to the store of facts that your brain contains as a result of your schooling, your work, your reading, and your association with your fellows? I am going to show you how you can test yourself, and see. best workers. Among a gang of pick-and- shovel laborers was found a man who got a higher score on the tests than the average physician had made! He was promptly transferred to a higher position that had been difficult to fill. Here the man The tests you will find here was happier, because his new are the kind given to college students to determine their mental abilities. They are an accurate measure of general intelligence—a quality that no amount of study will supply; a quality that the laborer, the mechanic, or the work permitted him to use more of his abilities, and be~ cause he no longer had to fool around at work that was not the right kind for him. What is your range of in- formation? Put a cross be- fore each of the words in this clerk who has not been through high school, or even grammar school, is quite as likely to pos- sess as the man who has earned a col- lege degree. To know the measure of your own in- telligence is highly important to you, and highly useful. It may show you, for ex- ample, that you are in the wrong job; that you are wasting your time in some occupation below your abilities, or that you are attempting to make your way ina business or profession that is beyond your powers. How logical is your thinking? The word elbow indicates a part of the arm; chimney is a part of a house. Of what isa speedometer a part? While some one times you, call out the thing of which each of the words listed below is a part. Take the words in their order, skipping none. Are you being timed? Ready. Go! leaf afternoon Germany nail floor week quart tooth chimes board casters Chicago tire beak paper If you completed this test in 23 seconds, you are up to the average of college students. If you did it in less, you are brighter than the average college student. It may seem strange to you that a simple test such as this—taking which is an exercise quite as fascinating as working the cross-word puzzles that are so popular now—should supply a reliable index to your intellectual powers. These tests, though, are not so simple as they may seem. They were devised by leading psychologists—by Dr. Alfred Binet in France, and by Dr. Henry H. Goddard, Tests of Your Ingenuity Fig. 1. All the blocks in the upper picture fitted together properly form an arrow such as is shown in the lower picture. With your pencil outline on the arrow just how each part will fit. If you can do this in less than a minute, you are above the average in solving puzzling problems. You will find the correct solution on page 158. Fig. 2. Arrange 11 matches as shown be- low. Remove three of them and leave two triangles. If you can do it in less than 10 seconds, you are above the average of college students. The correct solution is on page 158. some one keeps a record of the time it takes you to do this: It — sometimes said ——— women are more honest than ———. It may be ——— -—-——— are more honest ——— —-—-—-— long run, but there ———-— instances in which great ———-—— has been found in some ————— - Such, —— ———— was the case —— the recent criminal ——-— — which has received newspaper We are assured honesty of the man in this particular ——W—, but the honesty of the ——-—— is open to serious ————— A college student will fill in these blanks in three minutes. Many persons list that you understand: assay Beelzebub keel assuage Bessemer nullify astrology blather Othello Audubon Hauptmann paunch auk hypothesis revile Bancroft ichnography scup Mendel incubus Sudan mammal incognito terrapin A college student will have 16 crosses. Some of the funniest things imaginable are written in these tests at times. One college student, for example, said that Mark Twain was a steamboat; another that a revenue cutter was used on a mill- ing machine. Another was working on a test in which the problem was to draw in with a pencil the missing parts of several pictures. One of the pictures was a pig, with the tail missing, and the student drew horns on the pig’s head! I have found other students who were unable to detect that the eye was missing in a picture of a woman’s face. All of which is only another indication of what I said before—that going to col- lege does not supply brains. Abraham Lincoln and Edison never went to col- lege, but that they possessed intelligence nobody would deny. How are you on numbers? Maybe accounting or some similar line of work is your forte. Try the following test, to see whether you have a natural aptitude for figures. While some one times you, check each group that contains a number 6. The average college student can do this in 40 seconds. If you can better this time appreciably, it is a sign that you probably have a “‘good head for figures.” (Continued on page 158)

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46 POPULAR SCIENCE MONTHLY Never before has the glamour of ad- venture in searching the seas for sunken treasure so appealed to men’s imagination as it does today; for recent submarine inventions are making it possible to descend hundreds of feet beyond what here- tofore has. been the limit of human endurance. The armored chamber A Work Chamber on the Ocean Floor February, 1925 Sunken Riches Lure Amazing New Deep-Sea Armor Revives shown above is one of these new devices, invented by Capt. Charles Williamson of Norfolk, Va. Lowered from a floating barge, it rests on the sea floor, where the diver’s hands are free for work. It is designed to descend to a depth of 800 feet. The greatest depth possible hereto- fore has been about 200 feet May Recover Lusitania’s Wealth Will the all-metal armor shown above enable divers to recover the $5,000,000 that went down with the Lusitania, and now lies in 285 feet of water? The inventor is confident of working 1000 feet under- sea. Notice how the diver is lowered by a crane With this apparatus—a combina- tion grasper and sand sucker— two British contractors are at- tempting to salvage the famous Mechanical Claws Grapple for a Fortune English frigate Lutine, which sank off the northern coast of the Netherlands in 1797 with acargo of gold estimated at about $5,000,000

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ry, 1925 ves e new ‘harles ywered on the hands signed ) feet. ereto- feet ——_—___ nk he of 00 . ~— gebruary, 1925 Modern Adventurers Romantic Treasure Hunt in Wrecked Ships POPULAR SCIENCE MONTHLY How Divers Salvaged $30,000,000 from Laurentic The recent dramatic success of divers in recovering a golden cargo worth $30,000,000 from the wreck of the Laurentic, sunk by a subma- rine off the northern Coast of Ireland in 1917, has spurred other adven- turers to seek more of the sea’s treasures. Only a few weeks ago, four young Americans located the wreck of the Ward liner Merida, which went down in a collision off the Virginia capesin 1911. They are at work to recover her cargo of gold, silver, and jewels —a prize estimated at from $2,000,000 to $5,000,000. The above illustration shows how divers worked on the hull of the Laurentic, which sank in 90 feet of water In seeking riches buried with the frigate Lutine in 45 feet of sand, the earth and sand brought up by Washing Gold from the Ocean’s Sand nearer the grasper shown on the opposite page are carefully washed to recover gold and silver, as in the illustration Remains under Sea Four Hours It is claimed that four men can remain under the sea four hours in this huge diving bell recently tested near New York City. The four white disks are magnets by which the bell attaches itself firmly to a sunken ship during salvaging operations A Mechanical Sea Monster Picture this weird steel monster groping in the murky depths off the coast of Scotland in search of the fabulous treasures that went down with the Spanish Armada more than three centuries ago. Then you will have a real modern romance. The armor is so heavy that a man would be unable to move with it on land. It is electrically operated throughout. Notice particularly the claws that have the power of the combined grip of 100 men ~ ~ wy

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POPULAR SCIENCE MONTHLY February, 1925 A Thrilling Spi HESE six photographs are repro- duced from what is probably the most remarkable motion picture of an automobile racing accident ever taken. They show a racing car turning a complete somersault on the track, catapulting the driver high into the air; then, as he falls to earth again, rolling over upon him to crush out his life. It was by chance that such a dramatic picture story was obtained. The camera man was at the race track at Hawthorne, Ill., recently, ‘‘shooting”’ pictures of a pre- liminary tryout. Suddenly a stream- lined racer driven by Norbert Wylie, ap- proaching the grand-stands at a speed of more than 90 miles an hour, was side- swiped by another car. Wylie’s machine careened in a dizzy spin, toppled over and somersaulted. There was a sickening crash,-and the driver lay dead beneath the thundering speed machine of which a moment before he had been the master. T WAS all over so quickly that the amazed spectators hardly knew what had happened, yet the camera’s unerring eye had caught every detail of the tragedy. In picture 1 the ill-fated car is seen at the instant the driver lost control. It has skidded sharply and is tilted up sidewise on two wheels, about to roll over. ag ourtesy International News Reel on the Speedway 2. A fraction of a second later. The car has turned upside down, hurling the driver,into the air. 3. Wylie is seen falling in the path of the plunging machine. 4. Here the car has risen on its haunches, while the falling driver has almost reached the ground. 5. Like some brutal monster, the ma- chine, digging its sharp tail into the track, lifts itself upward, ready to strike at its fallen master. Notice the seat cushion leaving the car at the right. 6. The instant before the fatal crash, with the racing automobile completely off the ground. F

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y, 1925 vs Reel > The ng the » path on its oar has le ma- track, at its ushion crash, pletely February, 1925 POPULAR SCIENCE MONTHLY 49 Automatic Controls to Make Our Trains Safer How Machinery Prevents Collisions when By Norman C. McLoud N THE vestibule of a limited train I recently I saw the conductor, startled into sudden action, throw open the outside door and look backward. With his first move he pulled the overhead emergency cord. The swiftly speeding train jerked to a standstill in a manner that must have surprised the engineer as much as it jolted all the pa-sengers. In passing a signal tower the out waiting for human prompting. Its chief function is to prevent collisions, of which, in 1923, there were 938 on rail- roads of the United States, resulting in the death of 83 persons and the injury of 1660 others. To reduce this costly toll by safe- guarding against the failure of the human factor in railroad operation, 49 roads have installed automatic equipment on an average of 100 miles of track apiece. Human Hands Fail This means about 5000 miles of American railways under automatic control. The new devices are designed to guard against such possibilities as the sudden death of an operator in his tower or of an engineer in the cab of his loco- motive, and to protect the train against the unexpected stoppage of a train ahead, the approach toward a broken rail, or the peril of an open switch. They remove the danger that impends when a signal is obscured by fog, smoke, or other conductor had caught a flashing glimpse of the operator lurching unsteadily toward a window. Investigation revealed that the man had developed a sudden attack of illness and had fallen unconscious. Since the tower stood at the crossing of another important railway, the alertness of the conductor had made it possible to prevent disaster. This incident of travel illus- trates the importance of auto- matic train control, now manda- tory for the first time in the his- tory of the United States. The requirements became effective January 1, after several years of preparation. They were im- posed by the Interstate Com- merce Commission through per- emptory orders addressed to 49 important railways, issued in June, 1922, and stipulating that each road, within 2% years, should properly safeguard at least one full passenger locomo- tive division of main-line track. Automatic control is intended to do what was done by the con- ductor in the case of the fainting signal operator—and do it with- causes. UTOMATIC _ train-control devices are of three general types: The ramp system, elec- trical induction, and magnetic induction. All convey to the locomotive cab detailed infor- mation concerning the state of the track ahead. This is accom- plished through electric circuits of which the rails are the basic factor. When necessary, the devices seize control of the train and bring it to a standstill by sharp application of the air brakes. The ramp system ‘uses short lengths of a third rail, placed alongside the track at the ap- proach to a wayside signal. This rail, or ramp, is somewhat higher than the regular rail, and slopes at each end. The locomo- tive is equipped with two metal shoes, arranged so that they establish contact with the ramp. When the shoes slide up the in- cline at the end of the ramp, one of two things will happen. If there is a train that is too near ahead, a broken rail, or an Safeguarding the Limited A Chicago & Eastern Illinois limited train at a control ramp that automatically applies the brakes if the engineer fails to respond to danger signals. The ramp is the extra rail at the side of the track. The upper view shows the two metal shoes that establish contact with the ramp open switch, the ris- ing motion of the

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shoe operates a plunger that causes the completed circuit to apply the automatic brakes. On the other hand, if the track is clear, the rising motion is nullified by a contact device and brakes are not used. The electrical-induction and magnetic- induction systems dispense with the in- termittent ramp and operate continu- ously. Information concerning the track ahead is trans nitted through the rail cir- cuit and reaches the cab by means of induction, through the medium of coils or magnets placed alongside the rails. The locomotive is equipped with receiv- ers to pick up the induction impulse from the coils or magnets. The impulse thus communicated actuates the control ap- paratus aboard the locomotive and ap- plies the brakes when necessary. In some devices the impulses picked up by the receivers are said to be of sufficient strength to be used without amplifica- tion. In others the designers have pro- vided for amplifying the impulses by POPULAR SCIENCE MONTHLY vacuum tubes, similar to those used in radio. In the cab of an automatically con- trolled train in which I made a recent trip, the engineer sat facing an interior out- fit of signals, consisting of three electric lamps controlled by a speed indicator acting on the principle of a centrifugal governor. The apparatis was set to pre- vent speed of more than 60 miles an hour. For some distance we moved at less than 60 miles an hour. On a slight down grade the speed increased until the indi- ecator was above the prescribed limit, warning the engineer that he must reduce his rate of travel. The warning disap- peared assoon as the excessive speed had been eliminated. **Tt was up to me to slow down quickly,” the engineer told me, with a good- natured grin. ‘‘If I hadn’t, the blamed thing would have taken the train away from me.”’ Therein lies one of the important February, 1925 factors of automatic control. As long as the engineer is on the alert, he loses none of his responsibility or command. But he fails to heed the warning the brakes are applied automatically. He could not have allowed his train to maintain the high speed if he had tried. The centrif- ugal governor would have applied the brakes without a second warning. Tests on the Erie Railway have pro- duced striking results. Passenger trains of eight steel cars, running at 47 miles an hour, always have been stopped auto- matically within 1200 feet from the time of the automatic application of the brakes. Under company rules the non mal allowance is 1600 feet. Freight trains averaging 79 cars, with weight of 6326 tons to the train, achieved stopg within an average distance of 1713 feet) from a speed of 30 miles an hour. The program of the Interstate Com- merce Commission contemplates expan- sion of the automatic control to all roads. Artificial Throat WO men stood on a platform in Baltimore, Md., recently before a gathering of surgeons. , Neither had spoken in several years, their vocal cords having been removed in operations for cancer of the throat. They attempted to speak, but the results were only slight hisses from their lips and louder sibilant sounds as the air from their lungs sighed through the apertures in their throats left by the surgeons’ knives. Then Dr. John E. Mackenty, well- known laryngological surgeon, of New York, handed to each man a little device of rubber tubing and silver, quite like some odd form of smoking _ pipe. The rubber tube each man affixed to a pad that was strapped to his throat over the hole through which he had been breathing since the opera- tion that had taken his voice away. The other end of the apparatus—a tube of hard rubber resembling a pipe stem—each placed in- side his mouth. Again the men attempted to speak, and this time there issued from their lips intelligible, articulate speech! This was the first semi- public demonstration of the artificial larynx, an amaz- ing device developed by Dr. Harvey Fletcher, Raymond L. Wegel, and Clarence E. Lane, engineers of the West- ern- Electric Company, which ends the hitherto hopeless silence of those who have lost their vocal cords in operations for can- cer. The artificial larynx is not Returns Speech to at all a compiicated apparatus. It consists merely of a pad, strapped over the breathing aperture in the patient’s throat, a rubber tube through which air is carried from the lungs, a little cylindri- cal box containing a diaphragm of thin rubber, and another tube by which the air set into vibration by the rubber diaphragm is carried to the mouth. Movements of the lips and tongue then form the speech sounds just as in the normal act of speetsing. . The result is: speech that is entirely intelligible with volume enough to carry across a large room. Unlike natural speech, however, it is delivered in a mono- tone, since the rubber diaphragm that simulates tne vocal cords cannot be stretched and compressed at will to pro- duce variations in pitch. Fourteen per- sons have been using an earlier and less When Science Gives Back the Power of Speech How a victim of cancer of the throat uses the new artificial larynx that gives him back the power of speech, is shown by the figure on the left. An engineer of the Western Electric Com- pany is demonstrating to him part of the invention that simulates the action of the human vocal cords, removed in the operation for cancer. The patient is holding in his hand the box con- in an operation for cancer taining artificial vocal cords. These are actuated by air carried through a rubber tube from a hole in the pa- tient’s throat, while the patient forms the sounds of speech with his mouth through a tube resembling a pipe stem. The diagram at upper left shows how the mechanism is sub- stituted for the larynx, removed Cancer Sufferers perfect form of the invention for about » year. Now, though, the artificial larynx, will be manufactured in quantities that will make it available to all who require it., No attempt will be made to market it on; a profitable basis, it is announced. Those, who require one, yet cannot afford it will be loaned one. To those who ean afford . it, the price will be the exact cost of man- ufacture. | Pipoeke oun of the throat is extremely malignant, and victims survive only. from 18 months to two years without an, operation. Any form of local irritation may lead to the development of the dis- ease, common contributing causes being excessive talking or shouting, excessive smoking, and bad liquor. Since it is a disease not often encountered, some, times it is not recognized at once by, . physicians. The operation is exceedingly delicate, necessitating the removal of the larynx (the Adam’s apple) and the adjacent parts of the throat. One of the final steps in the operation is carrying the upper end of the windpipe forward into the wound and sewing it up in such a way that the windpipe communicates directly with the outer air. Henceforth the patient mouth. The artificial larynx may be used by the patient almost as soon as the wound in his throat has healed. The pad is strapped to his neck continuously, with a layer of gauze underneath to keep the dust out of his lungs. When he wishes to talk, he parts his shirt just below the collar-button, and attaches the rubber tube. Very little practice is required for the user to be- come expert, and thereafter talking imposes no strain either on speaker or listener. breathes through this aper-' ture and not through his, 34 rose~repaegwse Ss Woo.

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1925 z as one it +. not the trif- pro- ains San uto- time the nor- ‘ight it of tops feet? ‘om pan- yads. ut a rynx; that re it., it on; “hose, t will fford . man- mely: only. ut an, ation: e dis- being 2ssive. ; is aj some-, ie by; : icate,! x (the rts of in the + the dpipe vound such dpipe ectly air. atient: aper-. rh his, c may atient vound ealed. to his jith a neath of his hes to t just utton, ubber tice is to be- eafter strain tener. February, 1925 POPULAR SCIENCE MONTHLY 51 Newest Locomotive Marvels Giants of Electricity and Steam to Pull Our Trains [Ess than a century ago the grotesque wood- burning locomotives that hauled American trains did well if they could take a short train along a straight stretch of level track at 25 miles an hour. In less than a century these crude engines have been developed into the giants of electricity and steam that today carry us across the continent in less than five days and pull tremendous loads over mountain ranges. Below is pictured a duplicate of one of the world’s first locomotives, the “Blucher,” built by George Stephenson in 1814. It drew a train of eight loaded wagons weighing 30 tons at four miles an hour New Turbine Locomotive That the common type of piston locomotive is doomed, and will be succeeded by a turbine locomotive that is 10 times as efficient, was the recent statement of Henry Zoelly, noted Swiss locomotive engineer, in a report to the Ameri- can Society of Mechanical Engineers. “It is positively pitiful,” he said, “to see thousands of locomotives running with maximum over-all - efficiencies of from seven to nine per cent— very often as low as five or six per cent— whereas an up-to-date stationary steam plant attains with ease efficiencies in excess of 20 per cent.” Above is one of the newest types of turbine locomotives perfected in Germany. The tur- bine engine differs from the usual reciprocating a engine in that the steam pressure, instead of being exerted against pistons, drives : . Me 7 58 WM ai S10; KS rt Tn Soy Va . _’ against a series of vanes or buckets ona + i> . Serer ee rotating wheel, greatly reducing friction é } FE Ey = rs “mace A Gearless Giant One of the most efficient of the new electric locc- motives is the high-speed gearless type shown at the left, used in the mountains of the Pacific Northwest. The motor armatures are mounted directly on the axles, 12 in number. The total weight of the drivers is 458,000 pounds. The locomotive is in two similar units. Be- tween them is a cab con- taining a boiler plant for ~“s heating the cars of a pas- senger train. This loco- motive is said to be more than 90 per cent efficient Run by Storage Batteries The largest storage-battery electric loco- motive in the United States is shown at the right. It was put into service recently in the yards of the General Electric Company at Sche- nectady, N. Y., and is to be used for sw tch’ng on inter- connect ng track systems. Because of the necessity of recharging its batteries fre- quently, it is to be used only in a restricted area. The batteries consist of 100 cells with a total current capacity of about 1080 ampere hours, or 216 kilowatt hours

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52 HEN the United States mail- carrier put on the uniform of an aviator, from all over the coun- try came warnings of disaster. Airplanes sweeping through the black of night, struggling against wild storms, pilots guided only by feeble lights flickering upward at long intervals, deserts and mountains POPULAR SCIENCE MONTHLY service was introduced in Alaska. What had been a 35-day trip by dog sled was completed in less than six hours. It was shown that surface temperature could drop to five below zero and even lower, without offering obstacles to the satis- factory operation of the planes. Rugged february, 1925 Speedy Airplanes to Conquer Thrilling Stories of Mail Routes that Have Cost and strong currents usually make short work of it. Sometimes the break-up occurs when the carrier is on the ice with horse and sleigh. The sudden collapse brings great danger, and more than one carrier owes his rescue to the quick work of the coastguard crew stationed on Plum Island, close at hand, to be crossed, with help difficult to procure in case of accident—all in- troduced an element of peril into what should be surrounded with utmost safety—the delivery of our daily letters. But was danger really being introduced? On the contrary, the way was being paved for a far greater measure of safety in the postal service. Those who live in cities and towns may laugh at the assertion as absurd; but it is not. For there are hundreds of Uncle Sam’s postal routes where an airplane would represent the saf- Through the Ice of ‘‘Death’s Door’’ One rescue of a carrier from the break-up wag full of thrills. With the destruction of his path- way, the man _ found himself on an ice cake barely large enough to hold himself, his horse, and his sleigh. The crew of the coastguard station saw his situation and rushed to his aid. Broken ice surrounded the marooned carrier and: made it impossible to reach him, so the coast- guards were forced to combine seamanship with the methods of the plains. Their line be- This U. S. mail-boat is shown breaking through the ice past ‘‘Death’s Door”’ on the hazardous Lake Michi- gan star route between Ellison Bay and the isolated est possible method of travel—security for the carrier such as he never dreamed of. These are what are called the “‘star routes’’—the postal byways in the remote ends of the nation, where the carrier faces death and injury virtually every time he fares forth with his sack. Avalanches, floods, blizzards, drifting ice —these and other hazards of nature con- tribute to the perils of the carrier who serves the outposts of the postal service. In the last 30 months 55 carriers have given their lives in the performance of duty, and many others have been crippled and otherwise injured. These unsung heroes of the nation are the ones who will benefit more than any others from the introduction of the air- plane and other gifts of science such as the motorized snowsled and power ice- boat into the equipment of the postal service. The motorized sled, recently invented by a Finnish scientist, has aroused much interest in the Post Office Department. Here is a device that undoubtedly will prove an efficient ally to the airplane in cutting down the frightful toll in lives that for years has seemed inevitable in delivering the mails to such places as the frozen wastes of Alaska. Recently an experimental air-mail community of Detroit Harbor off northern Wisconsin mountains with passes blocked by avalanches were crossed easily. With motorized sleds to distribute the mail brought in bulk by the airplane, the perils of the carriers in these barren, snow- swept reaches virtually would disappear. Likewise, the successful establishment of transcontinental air-mail service, cut- ting the traveling time between New York City and San Francisco from four days to 34 hours, offers the possibility of covering perilous mail routes that now are served at tremendous risk. Such a one, for ex- ample, as that which extends from De- troit Harbor, Wis., past ‘‘ Death’s Door.” This stretch of travel is on the Lake Michigan water route that forms the sole channel of communication between Elli- son Bay and the community of Detroit Harbor. In open weather the route is without difficulties. From November to May it carries dangers that prove that **Death’s Door” is well named. HE chief trouble comes from drifting ice-fields. Extremely cold weather brings about the formation of an ice- bridge, but this seldom remains for more than a few days at a time. Shifting gales came a lariat. They lassoed the cake of ice, towed it through the water and over the surface of the ice until they brought carrier, horse, .and sleigh to a place of safety. Bucking the slush ice is another peril of the carrier who serves the route through Death’s Door. When the carrier cannot find solid footing for his horse and sleigh, he uses a launch. Sometimes the slush is, eight or 10 feet deep and impassable, in which case the carrier must fight his way back to the starting point and seek a fresh channel. At times the boat is caught in’ the drifting ice and carried out into Lake* Michigan overnight. , Ellison post office is on Washington ' Island, an area with a population of one thousand. During severe weather the island may be without mail for five or six days. Such interruptions are serious, for the residents depend entirely on the’ postal service for contact with the outside world. The parcel post is their sole source * of supply for medicine, provisions, and other necessities. In this case the mail-plane would remove the dangers of Death’s Door and

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Ost short 2ak-up e with ollapse an one . | a drifting ice-field in which they had become ‘wedged. They were swiftly carried down the lake and the islanders gave them up as lost. Asa final resort a cable message was sent to Kelleys Island. ‘Look out for the mail-carriers,’’ the message read. ‘‘They are fast in the ice and drifting your way.” Rescue parties were swiftly organized. Operations were concentrated at a point at which the drift was nearest shore, and here the brothers were rescued. Assist- ance came none too soon. The two men Their caps were exhausted and helpless. were frozen to their heads and their cloth-

Old and New Above is Alaska’s first air-mail plane, and be- side it is one of the dog teams that it is replac- ing. Experimental air- mail service between Fairbanks and McGrath —a distance of 300 miles—has proved that on. what formerly was a perilous 35-day trip by dog sled can be com- pleted now with safety in less than six hours IDITAROD

Lil dct ee SCALE OF MILES LA Map showing the direct 300-mile air-mail route between Fairbanks and McGrath; Alaska, as compared with the winding and much longer dog-sled route that it replaces dramatic adventure of the Hitchcock brothers is a living tradition with the islanders. The incident happened some winters ago, but it is still told as an ex- ample of what the carriers must face. The Hitchcocks had started for some of the smaller islands when they were caught in a violent storm and a heavy sea of running ice.. They could do nothing but run with the gale and the perilous MCGRATH Jes ALASKA DQG SLED ROUTE ———— AIRPLANE ROUTE ae 100

RUBY * ng OPHIR PW \us LAKE MINCHUMINA

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ing so completely covered and weighted with ice that they could not move. More than a bushel of ice was chopped from their garments after the rescue. The ironclad is one oi t:.2 institutions of Lake Erie. Perhaps it is best described as a combination sailboat, rowboat, ice- yacht and sled. When it can’t be moved as one, it becomes another. In a single journey it may be all four. The craft isa YUKON TAA a WIRELESS STATION Za _D CHENA pa CHATANIKA | ee NENANA® flat-bottomed skiff. For sailing in open water or on smooth ice the boat carries a sail. On the bottom are iron-shod run- ners for sledding. The sides are sheathed with galvanized iron as protection from the knife-blade edges of thin ice. Without this sheathing the ice would make short work of the wooden shell. ICTURE the condition of the isolated Lake Erie communities under a sys- tem of air-mail transport. Instead of facing the dangers of ice- and storm- swept seas, the carrier would cross the water at an altitude insuring complete independence of surface perils. Instead of drifting ice cakes he would have a clear airway. -The present journey of hours would be covered in a matter of minutes. Still another section where severe winters are a bitter enemy of the heroes of the mail service is South Dakota. Here one of the most daring of carriers was Reinhold Dreahn, who fought for many years, falling at last before the overwhelming forces of cutting wind and bliz-

zard sleet. His life was an endless chain of journeys between the post offices at Murchi- son and Buffalo. Storms found him _ unafraid. His one creed of service Raa FAIRBANKS was that the mails must WIRELESS move—the creed that A starion finds unfailing expres- S \) sion in the work of the postal servants every- | where. ye One Saturday after- J noon last winter Dreahn left Murchison for Buffalo on his semi- weekly trip. A fierce snowstorm was raging. With nightfall the cold became intense. Buffalo knew the man and his record and awaited his arrival with quiet confidence. But when on the Sunday Dreahn failed to appear, all Buffalo became anxious, and searching parties were organized. It was too late. Dreahn had made his last trip. _He had fought his way to

within a few hundred yards of the town, only to lose the struggle in sight of safety (Continued on poge 155)

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54 POPULAR SCIENCE MONTHLY February, 1925 | First Aid for Your Family What you should keep in your medicine cabinet for every emergency—How to safeguard against mistakes By John F. Anderson, M.D. HEN you open the door of your medicine cabinet, what do you see on its narrow shelves? Do you see articles that should be there for every. possible emergency, and of which your family physician would approve; or do you see articles he would not approve, and many of which may be dangerous or at least unsafe? The medicine cabinet should be well stocked and well light- ed for any emergency, says Doctor Anderson The daily papers tell us too often the story of what has happened to some one, usu- ally as the result of a night call on the contents of the medicine cabinet, because there was included a danger- ous drug among the real household emergency prod- uets of harmless character! Some member of the family, groping around in the dark, picks up the wrong bottle, and the mistake is not discovered until it is too late. These deplorable and pre- ventable accidents usually are due to the inadvertent swallowing of either one of the coal-tar disinfectants such as carbolic acid, cresol or the like, or tablets of bichloride of mercury. Dangerous drugs should be banned from every household medicine cabinet. The household medicine cabinet should be in the best lighted part of the bath- room, and so placed that when the mirror- fronted door is open, a light shines full upon its contents. It should be painted and kept in spotless wltite, and its shelves preferably should be of glass. What should we find on the shelves of this household emergency drug- store? Suppose we start our list with those products that may be used for the re- lief of indigestion and con- stipation, the two great American complaints. Sodium b'carbonate should be there for the first of these: A liberal pinch in half a glass of water is a good remedy for “heartburn” and other symptoms of indigestion. Bicarbonate of soda also relieves the sting of insect bites, eases the pain of superficial burns; may be used in solution as a gargle for a sore throat, and in a bath for tired feet. Truly this is the most use- ful of the contents of the medicine cabinet. For the relief of sluggish bowels or habitual constipation, there should be mineral oil, or liquid petrolatum, as the doctors call it; Epsom salts and castor oil (the tasteless kind for children). S WE have banned carboliec acid and the like, as well as bichloride of mercury, we should replace these danger- ous disinfectants by others. In their place let us put in tincture of iodine to be used as an application to cuts and wounds before the doctor arrives; chloramine-T as a general disinfectant and dressing for wounds of various kinds, particularly infected ones; boric acid as a prophylactic antiseptic and particularly for use in a solution as an eye wash, or douche. We must not omit a benzoinated cream to be used for the relief of chafing as well as chapped hands and lips, and as an ap- plication to insect bites. A tube of analgesic balm Sons, New York City. For Your Shelves The following list was com- piled by Doctor Anderson, who formerly was Director of the Hygienic Laboratory of the U.S. Public Service, and who now is Director of the Biologic Laboratories of E. R. Squibb & Sodium Bicarbonate—For indiges- tion, insect bites, slight burns, sore throat, tired feet. 3 Epsom Salts and Castor Oil pation and as a laxative. ‘ Tincture of Iodine—An emergency disinfec- tant for cuts and wounds. Sterile Bandages and Gauze—For dressing wounds in emergency. Boric Acid—Eye wash or douche. Benzoinated Cream—Relieves chafing, chapped hands, or insect bites. Analgesic Balm — For neuralgia or lumbago, bruises, painful and swollen joints. Milk of Magnesia—Mouth wash, mild laxative. Aspirin—For headache or head cold. Zinc Ointment—To relieve skin inflammation caused by poison ivy or poison oak. Aromatic Spirits of Ammonia—For fainting, nervousness, or giddiness. Thromboplastin—For nose-bleed. For consti- will often be found useful for rubbing in cases of neuralgia or lumbago, over bruises, painful and swollen joints, and as a counter-irritant in general. Milk of magnesia is recom- mended by dentists as a mouth wash and by physi- cians as an anti-acid and mild laxative; it should therefore be in the medicine cabinet. For solutions to be used as gargles, bicarbonate of soda or a solution of sodium chloride or table salt will do well. While. persistent headaches give warning that there may be some organic condition re- quiring the advice and ser- vices of a physician, there are nevertheless times when there is need of something to relieve a headache or pain of a severity and extent not re- quiring the services of a doctor. The best all-round product to include in the medicine cabinet for this purpose is aspirin. to contain acetanilid or phe- nacetin or even something more harmful; but aspirin has largely displaced them. Aspirin now is prescribed in the early stages of a head (Continued on page 156) For these uses the old-time | medicine cabinet was likely :

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1925, urn” | the n of ition bath -use- inet. Is or 1 be ; the or oil l and le of nger- their to be junds ine-T g for larly lactic in a ream : well n ap- balm ul for -algia uises, oints, nt in com- as a hysi- and hould licine to be onate n of e salt aches | may yn re- | ser- re are there elieve of a yt re- of a round 1 the this |-time © likely : ' phe- thing spirin them. ed in head ) February, 1925 HE world’s foremost artisan in camou- flage is Nature herself. To protect her creations she has endowed them with amazing tricks of deception. There are plants that entice unsus- pecting insects to de- struction by alluring flowers and _ imitation drops of honey. In the sea are countless creatures that conceal themselves from their enemies by transparency or by changing their colors. On land and sea are other creatures, naturally harm- less, that are made to ap- pear ferocious. Among the insects, an astonishing example of this protective deceit is the butterfly pictured at the right. This butterfly is protected from birds that are the prey of owls by the markinzs on its wings resembling the face of the owl. You will see how striking this resemblance is if you turn the picture so that it is upside down At first glance, would you believe that the tree trunk Pictured above held one of the gayest of moths? When in flight the Cato- cala flashes brightly col- ored blue hind wings; but as soon as it comes to rest, these brilliant wings are concealed beneath dingy fore wings that almost ex- actly match the bark of a tree. In this way, it can rest with the assurance of comparative safety from the birds that prey upon it * POPULAR SCIENCE MONTHLY ne ens Look at the twigs in the photograph below and see if you can find an in- sect. If you ex- amine them care- fully, you will see one long stick with legs and antennae. This is the Bacillus rossii, © commonly known as_ the “walking-stick.”’ It belongs to the grasshopper family, and is the color of tree-bark Courtesy Educational Film Exchange, 55 Gay Deceivers among the Insects Nature’s Clever Camouflage Protects Them from Enemies y Courtesy Educationa Film Ex- change, Inc. You would have to look twice, wouldn’t you, to tell that the object pic- tured above was other than just a plain leaf? This is one of several species of butterfly that are protected by their wonderful imitation of green or dead leaves. The camouflage is so : realistic that even the nerve veins running through the wings du- plicate the veins of a leaf. In some cases the butterflies appear to be weather-worn leaves Ba mae

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POPULAR SCIENCE MONTHLY February, 1925 UGeesh of Electrons Heard How invisible bombardments by the smallest particles of matter are magnified a million times—Seconds split into a billion parts— A promising treatment of tuberculosis—Other important new mileposts in the march of science are compared with the drop of a pin. Can you imagine, though, listening to sounds beside which the im- pact of a pin on a soft rug would be like a clap of thunder? Two American scientists did just that recently, when they devised an apparatus by which they were able to hear electrons, which, as you know, are the smallest known particles of matter—infinitesimal charges of electricity so tiny that their exact size could scarcely be computed if we were able to divide a _ millionth of an inch into a million parts. Dr. A. W. Hull of the General Electric | are compared faint sounds often thiosulphuric acid. The treatment con- sists of injecting the preparation into the veins or muscles. It is said to penetrate animal tissues quickly, thus reaching the tubercular clusters rapidly, and to act on the bacilli with sudden and deadly effect. Its destructive powers are said to be so rapid, in fact, that this in itself offers a danger to the patient, for the poisons from myriads of dead tubercle bacilli piling up in the system constitute a deadly menace. To counteract this toxic effect, however, a serum has been devised, which is reported to be entirely efficacious. Company, Schenec- tady, N. Y., and Dr. N. H. Williams of the University of Michi- gan, are the two scien- ~ tists who have -suc- ceeded in listening to the inaudible. By means of a vacuum- tube amplifier, they heard in a loudspeaker the bombardment of electrons against the plate of a vacuum tube. Such laboratory feats are highly important in bringing us closer to a knowledge of the. ex- act nature of that mighty force electricity, of which, science now tells us, our whole world and all it con- tains are composed. A New Weapon ITHIN a short time there will arrive in the United States from Denmark a supply of a chemical preparation that may prove to be one of the most important con- tributions ever made to the science of medicine. It is a treatment for tuberculosis, developed by Dr. Holger Mollgaard, professor of physiology at the Agricultural College of Copenhagen, which is said to have been employed successfully in clinical use by its dis- coverer. It is for the purpose of permitting the United States Public Health Service to subject the compound—called ‘“‘sanocry- sin’’—to thorough test that a supply of it is being shipped to this country. The preparation is a solution of a double salt of gold and sodium with Amplifier Magnifies Sounds a Million Times With this vacuum-tube amplifying apparatus, Dr. A. W. Hull, of the General Electric Company, and Dr. N. H. Williams, of the University of Michigan, listen to the noise of electrons as they bombard a vacuum-tube plate Reports from Denmark as- sert that “‘hundreds of cases have been treated success- fully in Copenhagen hospitals, some of them being persons in the advanced stages of the dis- ease.”” Dr. Allen W. Freeman, of Johns Hopkins Hospital, who visited Copenhagen re- cently, has reported to the annual conference of Ohio Health Commissioners that he observed the treatment being used with apparent success. However, conservative physicians, mindful of the failure of other loudly heralded medical discoveries, are seeking to prevent the hopes of tuberculosis sufferers from being raised too high until the new treatment has proved itself. Other Universes like Ours ERE and there in the sky are hazy patches of light, which as- tronomers call ‘‘spiral nebulae.” Just what they are, astronomers never have agreed, some holding that they are other faraway “‘ universes” or stel- lar systems like the one'of which our earth is a part, while others have contended that they are within our universe,about as far distant from us as our faintest stars. A discovery in support of the first theory was made recently by Dr. Edwin Hubble, of the Mt. Wilson Observatory in California, who announces that his in- vestigations show the spiral nebulae actually to be inde- pendent universes — suns, stars, and planets such as those of our universe—and six quintillion (6,000,000,- 000,000,000,000) miles or more away from us. Such figures mean little to us. We can, though, understand Doctor a 7 = = awe eel ~*~ S Sa — Doctor Williams before the loudspeaker, listening to the sounds made by the smallest known particles _

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1925. ians, udly king losis until f. Ss are 1 ase Just mers some other stel- ne’of part, nded | our stant stars. ort of made .dwin Jilson ornia, is in- spiral inde- suns, ch as —and ,000,- 2s OF little ough, doctor , to ples Sn i fo February, 1925 Hubble when he says that the light from the spiral nebulae, traveling 186,000 miles a second, takes one million years to reach the earth! In other words, his com- putations were based on light waves that started toward the earth a million years before his telescope was mounted, and have just now reached here. He does not say, however, that these inconceivably distant *#bjects mark the limits of space. Other galaxies of stars— other universes—probably are still more remote, he says, and appear smaller in consequence. Smallest Time Measurement PLITTING seconds into a billion parts was the amazing accomplish- ment announced recently by Prof. Paul Heymans, professor of theoretical physics at the Massachusetts Institute of Tech- nology. After a gasp of astonishment that any one could make a measurement so minute, the natural question occurs: What of it? What use shall we ever have for a method .of measuring a billionth of a second, or one-hundredth of one-billionth of a sec- ond, as Professor Heymans thinks we may detect soon? One of the possible uses might be to determine the difference in time it would take for two bodies of the same shape, but of different materials, to fall from the same height. This would throw tremendous light upon our knowledge of what is inside the earth. For a long time geologists have based their theories on the assumption that all materials fall to the ground from the same height in the same time. But by means of the new instrument, it may be learned that the force of gravity varies in different substances. If it is true that the gravity pull in the earth varies toward different objects, this knowledge would be tremendously important in determin- ing conditions in the interior of the earth, and might prove of great consequence in studies of earthquakes and eruptions. Another application of the time-split- ting device might be to determine in which mediums electricity travels fast- est. This would be valuable in designing X-ray tubes where the velocity of elec- tricity must be introduced to make.a cor- rect design. Studies might be made, too, of.the actual mechanism of the conduc- POPULAR SCIENCE MONTHLY tion of electricity through solutions. This would prove of immense importance in the electrochemical and _ electroplating industries. This remarkable apparatus is a modification of one devised by Pro- fessor P.O. Pederson at the University of Copenhagen. The measurement is made by employing so- called ‘‘ Lichtenberg figures,’’ which man- ifest them- @: WY selveswhen 4. — Splitting a Second Dr. Paul Heymans, pro- fessor of theoretical physics at the Massa- second into a billion parts. an electric wave is reflected from an electrode. When two electrodes are placed side by side at a certain angle and distance, the Lichtenberg figures meet. The position of the meeting line depends upon the time that has elapsed between the times that the electric waves reach the electrodes. The rate at which these fig- ures are formed is so extremely large that intervals of time from one-thousandth of one-billionth of a second may be detected. A Radio Compass for Flyers NOTHER forward step in commer- cial aviation was taken a few weeks ago when Lieut. George W. Goddard flew in an army plane from Dayton, Ohio, to Moundsville, W. Va., through virtually continuous haze, guided entirely by radio compass, steering only in response to signals from transmitting stations at his starting place and destination. The radio compass for aircraft was per- fected by the Army Air Service and the Signal Corps. The pilot wears a close- fitting helmet equipped with ear phones, and his hearing of the signals is facilitated by long exhaust pipes that carry away the sound of the motor explosions. A 300-foot weighted wire, suspended from the plane, serves as an aerial, and the receiving set is ‘‘grounded”’ on the body of the plane, While the pilot remains on his course, he ‘hears only a constant string of “‘dashes’’ from his radio receiver. Should he veer to the left, he is warned by hearing a 57 “dash” followed by a “‘dot” every 10 sec- onds. If he goes off course to the right, he hears “‘dots’’ followed by “‘ dashes.” Lieutenant Goddard’s flight was made on a direct beeline and in exceptionally fast time. © Keystone chusetts Institute of Technology (left) and his assistant, Nathaniel H. Frank, working at the laboratory apparatus with which they have succeeded in splitting a The measurements are made by means of so-called “Lichtenberg figures,”” shown in the photograph at the left, which are. produced when an electric wave is reflected from an electrode by laboratory methods Drops of Electric Fire (LOWING, golden droplets of liquid fire, a new and spectacular type of electrical discharge, were discovered re- cently by Dr. Irving Langmuir, C. G. Found, and A. F. Dittmer of the research laboratory of the General Electric Com- pany at Schenectady, N.Y. This phenom- enon is expected to lead to a better under- standing of what takes place in a vacuum. The globules were observed when a trace of tungsten was introduced in a dis- charge tube filled with argon. They seem to have characteristics similar to those of ball lightning, to which so many peculiar antics have been attributed. The nature of the globules in this experiment, there- fore, has led scientists to conclude that in the strange ball lightning there is an outer surface of positive electric charges within which are imprisoned negatively charged incandescent particles of matter. The tube used in the experiment has a tungsten filament at one end, heated toa glow by low voltage. High voltage be- tween the filament and a small plate electrode at the other end of the tube com- rletes the circuit. Pure argon, an inert gas, is sealed in the tube at low pressure. By altering the current passing through the tube, tiny particles of the tungsten filament are made to “sputter” into the argon vapor. This small amount of tung- sten emitted produces .an astonishing effect. When a magnet is brought near, droplets are formed. The size of these can be varied from the tiniest of drops to the size of a pea.

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Six Handy End Wrenches Assembled on Ring A SET of six very serviceable end wrenches assembled on one ring forms a useful tool for work about the house or in the garage. “The smallest fits hexagonal or square nuts measuring five- sixteenth inch; the largest is for five- eighth-inch nuts, while the other wrenches fit nuts of one-eighth-inch gradations be- tween these two measurements. The wrenches are handy for the car, the lawnmower, vacuum cleaner, radio work, and other purposes. Average Life Is 56 Years HE average length of life in the United States now is 56 years, an increase of 15 years since 1870, according to a recent report of the U. S. Public Health Service. In the sixteenth century human life aver- aged only between 18 and 20 years. POPULAR SCIENCE MONTHLY February, 1925 Better Tools and New A Portable Soldering Outfit for Linemen How a lineman carries the portable solder- ing outfit on his back while climbing a pole HIS portable, compact soldering out- fit is said to enable telephone linemen to accomplish more work in a day and do it with more safety than by the older methods. While climbing a pole, the lineman car- ries a tank of acetylene gas, asolderingiron, and torch attachments, all strapped to his back and out of his way. The outfit may be used for overhead line, or underground cable jobs. The flame is easily controlled and not Automatic Signal Replaces Traffic Cop LOOMFIELD, N. J., is cutting down its police force by installing electrical automatic traffic signals. The “stop” and “go” signs revolve at regular intervals, which can be shortened or lengthened to meet the The old and the new in traffic reg- ulation—a_ uni- formed traffic cop standing beside the new auto- matic “‘stop’’ and “go” signal requirements of any particular crossing. Tests have shown, it is said, that the signs will operate successfully and that they are sufficient warning for automobile drivers to know when they are supposed to halt. It remains to be seen, however, whether mechanical traffic officers of this kind will command the same obedience that a policeman will. Coastguardsmen Rescued 2462 Persons in Year THE army of thousands of men of the U.S. Coastguard Service, who patrol our 13,000 miles of coastline as methodic- ally as a ship’s deck, constitute the most complete life-saving organization in the world. During the 12 months ending last July 1 men from coastguard boats and stations rescued 2462 persons from posi- tions of peril. There was never a day in the year in which guardsmen did not per- form some service to vessels or persons in distress. Scattered along our coasts are hundreds of stations, fleets of boats, and wrecking machinery units, linked by telephones and by the new radio receiving and broad- casting stations. This vast machinery can be set in operation a few minutes after a distress signal is picked up from a ship at sea, andin this way any emer- gency can be met. affected by the weather, a valuable feature for linemen, whose most important work is often done in the worst weather, as thunderstorms and snowstorms are the worst enemies of telegraph poles and lines. Newest Rope Fire Escape Has Safety Control 7 ERE is a new safety fire-escape de- vice, consisting of a rope fitted with combination slide and clamping castings. In case of fire, the person trapped in a burning building uncoils the escape rope, and slides the casting along the rope so that it rests just below the window-sill. A loop of rope fits around a person’s body under the arms. Sliding down the rope, he governs his speed by manipulat- ing a brake-control wheel on the slide with his right hand, while grasping the body of the casting with his left.

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pure rork , as the and ye e de- with tings. lina rope, pe so sill. ‘son’s n the pulat- slide g the February, 1925 POPULAR SCIENCE MONTHLY Labor-Saving Methods Fighting Perilous Mine Dust with Cannon Mle HOOTING at dust with a cannon is a new and strange method by which the Federal Bureau of Mines expects to reduce the annual appalling death toll in mines caused by the many coal-dust explosions. The dust cannon is mounted on a mine car and moved quickly to any part of a mine where danger is believed to be immi- nent. The gunner fires a charge of black powder, sending the dust, if there is any, spraying in all directions. The seriousness of the inflammable dust menace is being realized more and more, and the government is experimenting with many devices to fight it. The dust cannon shown in the photograph is con- sidered especially practical because of its compactness and the ease with which it can be moved. A Simple and Easy Way to Mend Shaky Chairs Pisst aid to shaky furniture comes in the form of small pen-shaped metal pieces that fix loose chair parts perma- nently and without nails or glue. The metal piece is inserted in the rung or loose arm piece, and driven in as shown in the illustration. Cheer for the Low-Brows YOU have a low brow, it is no sign that you are less intelligent than a person with a high brow, according. to Dr. Ales Hrdlicka, curator of physical anthropology at the National Museum, Washington, D. C. Protector removed A Sanitary Earpiece THE principle of the sanitary paper drinking cup has been applied to the telephone receiver by José A. Dominguez of Ma- yaguez, Porto Rico. The device, a sani- tary ear protector for radio as well as telephone receivers, is cup-shaped, of strong paraffined paper crimped and pressed so that it will fit easily over the end of the receiver and stay in place without further attention. Since:the cost of each protector is ex- ceedingly small, the inventor proposes that they be installed in public telephone booths and each used only once. Thus every user would be assured of a fresh and Sanitary receiving earpiece. After each telephone call, the old pro- tector would be thrown away and a new one put on by each subscriber. ee Protector in place New Office Desk Built on Sectional Plan BOING your own desk to fit your own particular needs has been made possible by the recent invention of a sec- ‘tional desk designed on much the same principle as the sectional bookcase. The units are manufactured in standardized dimensions so that filing cabinets and drawers of specified sizes can be installed as desired. The foundation units of the desk are two low stools with four legs each. On the flat tops of the stools are placed the side cabinets and drawers, which are held firmly together by means of locking pins. On the cabinets rest the flat desk top, under the center of which is attached a shallow drawer for writing utensils and other small articles. The manufacturers claim that the units, when assembled, provide a sub- stantial and durable desk for office use. How the sectional office desk is as- sembled. Notice how the side cabi- nets rest on low, four-legged stools, and in turn support the flat top of the esk

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New Split Cane Rod for Deep-Sea Fishing g aberheomaogd months are required to construct the newest type of deep-sea fishing-rod, designed by an English man- ufacturer especially for landing big game fish. It is known as a “‘split cane rod,” and is equipped with an enormous brake reel fitted with a brake band not unlike that of an automobile. The brake is operated by a lever. The rod has a core of highly tempered steel surrounded by two or three layers of cane strips. A cork handle is provided for a better hold. # c An Adjustable Desk Chair N OFFICE chair with adjustable back rest and narrow seat has been designed recently to enable desk workers to sit with correct posture and less fatigue. The chair automatically swivels to fit into the hollow of the back where support is needed. Each chair may be adjusted to suit the user. POPULAR SCIENCE MONTHLY February, 1925 Novel Appliances Revolving Lamp-Shade Tells the Time— OME can tell time during the day by looking at the sun. Now, by means of a curious new invention, any one can tell time at night by looking at alamp. It is a special sort of table lamp, with a shade that is turned by clock works contained in the base of the lamp. The shade makes one complete turn in 12 hours. A pointer at the edge of the shade indi- eates the time as marked by perforated figures and dots on the shade. These are not conspicuous and at first glance a visitor would not suspect the double func- tion. of the attractive bronze-finished lamp. This novel lamp-clock has a 21-day movement. A key for winding it is under the lamp base. It will be observed that the photograph was taken at 1.05 o’clock. THE world’s record for bricklaying is claimed by a foreman bricklayer of Shef- field, England, who recently laid 809 bricks in an hour, or more than 13 a minute. One-five by the lamp-shade clock Complete Kitchenette in a Small Cabinet AN ENTIRE kitchenette in what ap- pears to be a refrigerator is a new convenience for those who happen to live in one or two rooms, but cling to their liking for home cooking. A table providing room for three per- sons can be attached to one side of the cabinet, so that a meal can be served easily. An ironing-board, too, hangs on the back of the kitchenette. Either electric stove or gas plate may be used for cooking. If elec- tricity isused,open- ing the lid auto- matically connects the electric cur- rent, and closing the lid shuts it ‘off. The stove is in a compartment at the top of the eabinet, while in the lower compart- ments are shelves to hold large cook- ing utensils and food containers. Finished in wood tones or white enamel this com- pact outfit occu- pies about’ the same space as an ordinary easy chair. On the inside of the front door hang otherutensils: a rack for dish towels, and a small shelf for milk and cream bottles. This door is hinged in the center so that when it is opened it swings outward, providing convenient access to the articles on the back of it. These two photographs show clearly how the compact kitchenette appears when opened for use and when closed into a neat cabinet that occup‘es very. small space in an apartment. Notice the cozy folding dining-table hinged to one side of the cabinet; also the compact stove compartment at the top of the open cabinet

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ned it enient f it. graphs ow the henette opened n closed net that small rtment. folding nged to cabinet; ct stove at the cabinet February, 1925 POPULAR SCIENCE MONTHLY for Every-Day Use Self-Standing Golf Bag Replaces Caddy How the golf bag supports itself O ELIMINATE the bother of con- stantly picking up a golf bag after the completion of each stroke, when the caddy is not on duty, Robert L. Fargo, of Chicago, Ill., has invented a self-standing golf bag. Two legs attached to the top of the bag are so arranged that they will swing out into place when the bag is tipped. Acting like the legs of a tripod, they hold the bag in a slanting position, keeping the clubs within easy reach and saving wear on the bag. A CHEMICAL product resembling glass and useful for many of the same purposes recently was perfected by Fritz Pollak, a German inventor. It can be rolled, bored, polished or cut, without the tendency of glass to splinter. Because of this quality it is usefu] especially for automobile win- dows, optical instruments, ornaments, and toilet articles. The inventor arrived at this product by condensing carbamide and theo-carbamide with formaldehyde. “Help Yourself” Service for Soft Drinks BSERVING the general popularity of “‘wait-on-yourself’”’ devices in use in the larger cities, a New York inventor has produced a container for iced bottled soft drinks, from which the customer can choose for himself his favorite brand. He opens a lid at the top of the beverage dis- penser, then turns a handle, which re- volves a tray inside, until the desired bottle is reached. There is a bottle opener at the side of the dispenser. When the customer has opened the bottle and consumed its con- tents, he places the empty bottle in a compartment at the bottom of the dis- No attendant is required to dis- pense soft drinks, where this self- service apparatus is installed penser, and pays the cashier his reckoning. Besides giving more efficient service, it is claimed that this method of self-service lowers expenses for labor and cuts the cost of ice bills. New Needle-Guiding Button NEEDLE-FINDING button is a recent invention designed to make sewing on buttons less tiresome. The new button is said to save the worker’s time by encouraging the needle to slide easily into the thread holes. The under side of the button is molded in such a way that wide- mouthed channels guide the needle toward the holes. In- - stead of having perpendicular sides, the perforations are funnel-shaped with smooth and slop- ing sides, so that the needle glides readily into the proper place with- out hitch or hesi- tation. The ar- rangement of the holes also distrib- utes the stitches over a wide area of cloth. A cupped por- tion on the rear or cloth side receives the mass of thread that it is custom- ary to wrap around the stitches pass- ing through the holes. This makes it possible for the button to lie flat against the surface of the garment. 61 A Compact Electric Motor for the Phonograph ‘THIS new electric phonograph motor recently perfected is said to be the first of its kind that runs without belt, gear, or friction disk reduction. It has a direct drive and will run at a constant speed at the low rate of 40 revolutions a minute. Its maximum speed is 150 revo- lutions a minute. The. motor is very compact, small enough to be put into a portable phono- » graph outfit.and powerful enough to run the largest phonograph. It operates on any 110-volt circuit. An Auto-Cleaning Sponge that Stays Wet \ A RUBBER sponge, kept wet by run-; ning water, is a new time-savingy invention for cleaning an automobile. At rubber tubing is fastened to the sponge» through a hollow handle and the other end of the tubing is attached to a faucet or’ garden hose. A small stream of water is’ sufficient to keep the sponge moist.

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62 POPULAR SCIENCE MONTHLY February, 1925 Oddities Picked up Ukelele in Cane—Lifeboat on Wheels— I Cane-Ukelele A walking-stick that can be converted instantly into a ukelele is the work of Morris Roth- man, of Bayonne, N. J., shown with his inven- tion at left and below

Ship Knees from Giant Roots One of the oldest of crafts is that of digging ship knees—the T wooden supports formed from giant roots, that are used in st constructing the stem and stern of a wooden ship. The photo- TI graph shows the largest ship knee ever dug, eight feet eight we inches thick at base. It carne from a Pacific Coast fir-tree

sR INRA IOS 8S ATE

, EN 0: < ser Old Railway Caboose a Monument Lifeboat on Wheels Launches Itself A railway caboose makes a strange monument, yet this one This self-launching lifeboat was the center of interest during undoubtedly deserves such an honor; for in it, 41 years recent tests at Cleethorpe, England. The motor that drives the ago, was founded the Brotherhood of Railway Trainmen. propeller also drives the self-launching mechanism which consists The historic car was placed recently in an artistic con- of a pair of wheels beneath the hull. The boat is 40 feet long crete and tile pagoda in Neahwa Park, Oneonta, N. Y. Colonial Hammer This quaint cobbler’s ham- mer was used to repair shoes of Washington’s soldiers at Valley Forge

© Keystone Operating on a Horse An interested audience of veterinarians and farmers is shown at the right witness- ing a demonstration operation at Purdue University, Indiana. The patient is a horse suffering from the poll-evil, a dis- ease that necessitates a difficult opera- tion. The animal is strapped and chained to the operating table. Horses that once had to be shot now find their way to hospitals where they often are cured and saved for more years of service

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925 1g 1e ts sihivenry, 1925 POPULAR SCIENCE MONTHLY 63 by the Camera Left-Handed Watch—Fireplace j +e it a ee a al i al Me ie ~ a RE AN ie ik ae kl: A Fireplace Studded with Gems Twenty-six different kinds of precious gems and metals aye in the stones of a fireplace in the home of M.A. Barr, at Valley Forge, Pa. The central piece is a solid 300-pound lump of jasper. The stones were found recently on the farm of Mr. Barr, who is seen in the picture Man of Jewels Runs Backward A left-handed watch that runs backward is the work of Richard F. Mason, who is a jewel- er of Columbus, Ohio A Stack of Horseshoes This strange-looking stack is a pile of horseshoes removed during the last. 11 China Has a Bridge of Porcelain One of the world’s most unusual bridges, near Peking, China, is made entirely of porcelain, each piece of which has been carefully hand modeled—a fact that goes far to explain its artistic lines and beautiful curves =. years by three black- smiths of Ed- wardsville, Iil., shown above ‘‘Science’’ in Sculpture At the foot of a great statue of Christo- pher Columbus, made by Arnaldo Zocchi for the Argentine governinent, is this group depicting “Science.” The central figure holds a lamp, depicting the search of scientists for hidden truth Cattle Cleaner Show cattle always receive exceptional care. But it has remained for an Iowa cattleman to employ scientific dry cleaning on his animals. Before any of his herd enter a show or sales ring, the vacuum cleaner re- moves every speck of dust from their shining bodies

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—T. oe Track-Laying Machine Aids in Railroad Building HE size of railway gangs is said to be greatly reduced in southern Florida, where a contractor is employing a new construction outfit consisting of a loco- motive and two flat cars loaded with ties, rails and a gas-driven traveling crane. The traveler picks up the ties and rails in bunches and carries them to the road- bed in front, where workmen lay them. POPULAR SCIENCE MONTHLY February, 1925 Ten Ingenious New Unusual Machines and Engines Built Diesel Engine Runs IDUE to the necessity for coal conserva- tion, European engineers have been striving for an efficient locomotive that would be run by other means than steam. Here is shown one of the newest designs, a Diesel electric locomotive built in Ger- many for negotiating more quickly and economically the vast stretches of terri- tory on the Russian steppes. Electric Milk Truck Has Automatic Brakes HE driver of [f& this ingenious : new electric milk wagon is his own self-starter and brake. He stands on the running- board as he drives fromhouseto house along his route. As soon as he jumps off, freeing the platform of his weight, hydraulic brakes are applied automatically to the car. cde Milwaukee Railroad Plans to Electrify System preneay for electrifying the entire sys- tem of the Chicago, Milwaukee & St. Paul Railway, operating lines throughout the West are being formulated by officials of the road, according to recent reports. The Milwaukee already operates 660 miles of electrified road over the Cascades and Rocky Mountains. The vast new project is said to have had its origin in an offer by Henry Ford to supply power for the railway system from his hydraulic plant which is being completed on the banks of the Mississippi River at Minneapolis. To this plant the railroad has constructed a bridge across the Mississippi at a cost of $3,000,000, and plans to handle the freight from Fords’ accessory plants operated in connection with the electric power plant. All terminal switching will be done by electric power when the project is com- pleted. Electric Locomotive The locomotive is equipped with power- ful Diesel oil engines, which generate elec- tric current to drive the locomotive. This transforms a railroad into an electric line. New Type of Lightship for New York Harbor HE last word in lightships is the Five - Fathom Light, designed for duty off New York Harbor. Two mast lights will flash each night and powerful radio equipment will assist in protection of the great har- bor’s shipping. This latest of Uncle Sam’s coastal safeguards has a gross tonnage of 825, is 146 feet long, and has oil- burning engines. Electricity Replaces Steam in Road Roller _— a steam roller belonging to an electric railway and light company in Milwaukee, Wis., needed extensive re- pairs, it was suggestedthat it be remod- eled to use current from trolley circuits operated by the firm. The electric motor was mounted so that it drives the pinion formerly driven by the steam engine, and the electric roller is operating very successfully on streets where the car lines supply power. Feb 2 - sa odtud m

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‘ystone DOWer- e elec- . This ic line. ip or al 4

er firm. ted so driven lectric lly on power. .

February, 1925 POPULAR SCIENCE MONTHLY Products of Mechanics to Increase Our Every-Day Efficiency

Twin Motors Drive Streamlined Hydroplane HIS strange craft, shown lying at anchor on the Danube River, is a giant hydroplane of unusual design re-

Huge Transformers Built to Test Insulators HESE three huge step-up transformers, cap- able of producing electrical tensions of more than a million volts, are part of the equip- ment of an enor- mous new all- metal electrical laboratory recently completed by the Compagnie Géné- rale d’Electro Céramique at Ivry, France. The laboratory was s built to test electrical apparatus de- signed to withstand high voltages, par- ticularly porcelain insulators. Note size of transformers compared with the men.

cently built in Vienna, Austria, for W. D. McDaniel, an American. It is run by two giant six-cylinder motors driving four-bladed propellers. It is said to be capable of developing 160 horsepower and very great speed. By having a stream- lined body and shallow draft, wind and water resistance are reduced to a mini- mum. A roomy passenger cabin is pro- vided behind the sloping bow of the craft.

Safety Stop Sets Engine’s Brakes Automatically ‘THE automatic train stop pictured above, designed to prevent collisions, is the recent invention of British railway engineers. A projecting arm from a device at the side of the track strikes a prop held between two metal arms projecting from the locomotive. The upper arm drops, setting the air brakes of the locomotive. Pumps sini Lake Water into Dry River-Bed

| Odd Railway Car Seca’ by Mokouenall NOVEL railroad inspection car pro- pelled by a motorcycle was con- structed recently in India. When the proreycte, fitted with an eight-horse-

power engine, is required for use off the tracks, it can be detached from the truck in a few minutes. When driving the truck, the cycle is me! §=6 “| installed when the level of scenic Lake Tahoe sank so low that the natural overflow of water into the Truckee River stopped entirely. They were set about 300 feet out in the lake, in three feet of water, and have kept a continual swirl of water going over the lake rim into the dry river-bed, pumping from 115,000 to 120,- 000 gallons of water a minute. Since they were placed in operation, the pumps have lowered the level of the lake more than two feet.

May Revolutionize Motors GAS turbine engine that, it is claimed, may revolutionize automo- bile and airplane motors is being per- fected by a French engineer. It is said to combine the advantages of the explosive gas motor and the steam turbine. Recent tests before officers of the French Air Service, are reported to have given complete satisfaction, the engine turning smoothly at the rate of 1500 revolutions a minute.

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66 POPULAR SCIENCE MONTHLY February, 1925 “John,” a 150-Pound Dummy, Tests Air-Mail Parachutes ‘ Ce eae the fuselage of the airplane shown in the above photograph hangs ‘‘ John,” a 150-pound dummy, who has made more parachute drops than any other member of the government flying personnel. The man-sized dummy is used to test thoroughly scores of para- chutes recently purchased for air-mail pilots who must fly often in extremely adverse weather conditions. Using the Salt Lake City air-mail field as a base of operations, an army plane conducts the tests in which “‘ John” is put through a grueling series of parachute drops. At an altitude of 2500 feet the dummy is cut loose, descending from a unique releasing device under the fuse- lage. If the parachutes pass the tests with the dummy, they are considered safe. A NEW record for slowness in flying was established recently by Captain Leprier, a French naval officer, who piloted a spe- cially designed machine ‘at a speed of only 8114 miles an hour. Smallest Airplane Weighs ay aoe Foun ERE is what experts have described as the smallest practical airplane in the world. It is known as the “Hummer” and was flown at a recent air meet recently at Day- ton, Ohio, by its builder, Bert Mix, an airplane me- chanic. The “ Hummer” weighs only 221 pounds. It has a spread of 12 feet, goes 75 miles an hour and makes about 50 miles to the gallon. The ‘‘Hummer,’ ] with its owner and builder, Bert Mix F Homemade Metal Monoplane with Folding Wings Fits in Garage The homemade monoplane at Logan Field, Md., following successful test flights. The plane was constructed entirely of duralumin. The wings can be folded for storing the plane |} A HOMEMADE all-metal monoplane of duralumin, built in a back yard with comparatively crude tools, can be folded to fit in a garage. The designer, W. H. A. Boyd, of Baltimore, Md., did not know how to fly, nor did his father, W. B. Boyd, nor brother, C. M. Boyd, * who helped him build it. Lieutenant Leo. M. Willinger tried oul the plane on Logan Field recently with} great success. to an altitude of 2500 feet, and made a speed of 90 miles an hour. Its low horsepower, 40, made rising} from the ground difficult, but this is to be remedied by installing a larger motor. A striking point in the construction of | the plane is the absence of bracing wires. | Made entirely of duralumin, the plane weighs only 800 pounds and has a wing; spread of 30 feet. By removing two pins on each of the wings, they can be folded so that the plane can be stored or shipped | easily. When folded, it is only seven feet wide. It can be knocked down in 15° minutes. On two occasions he flew |

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plane - yard an be signer, i., did ather, Boyd, * | od out: r with | e flew. ade a- rising } 3 to be Or. | ‘ion of ; wires. | plane’ 1 wing ; ‘oO pins folded hipped | on feet. in 15) February, 1925 POPULAR SCIENCE MONTHLY 67 Powerful Portable Searchlights Guide Air-Mail see O AID United States air-mail pilots : in making night landings, new port- able searchlights recently have been in- stalled at Crissy Field, San Francisco. On clear nights, it is said that pilots can see the piercing rays of these 450-million- candlepower lights when they are from 100 to 150 miles distant. The lights have 36-inch lenses. Since the inauguration of night flying in the mail service, which has meant great economy to business in the United States on account of time saved in correspond- ence, many types of electric beacons have been tried out, some on high towers. The new portable type is expected to prove especially valuable since it can be moved about on the landing-field under varying conditions to the position most helpful to the landing planes. To accomplish this, each searchlight is mounted on a wooden platform supported on alow metal frame with four automobile wheels. Hundreds of feet of cable that carries the current from power source to the light is wound on a reel at one end of the truck. This cable is paid out or reeled in as the searchlight is wheeled from one position to another. ig The new portable searchlight, showing the reel that carries the electric feed line In the photograph above are seen two United States air-mail employees testing one of the — at Crissy Field. Air Freighter Carries a 2700-Pound Carséo AERIAL freight- ing appears definitely to have outgrown the pos- sibility stage. This sky cargo ship runs regularly between London and Paris, transporting per- ishable products and goods to fill special orders. It carries a cargo of 2700 pounds, or nearly 11% tons. The photograph shows how the air- plane freighter is loaded. British Government Orders Two Giant Airships OLLOWING a recent decision to redevelop airship transportation in England, the British government has just ordered the first of two giant dirigibles, each of 5,000,000 cubic feet capacity, for transportation of passengers and freight. One of the ships, it is understood, will fly on regular schedule from England to Egypt and India. The cost of the first ship, it is estimated, will be about $1,600,000. Its length will be 695 feet and its greatest diameter 132 feet. The contract specifies that the structure and other fixed weights must not exceed 90 tons. Its range will be 2500 miles, and it will be capable of carry- ing 120 passengers and 10 tons of freight. Beside 30 two-berth cabins along the sides of the vessel, there will be a smok- ing-room, a lounge large enough to dance in, a kitchen, and quarters for a crew of 40. Aviator Builds Baby A REMARKABLE new type of small, baby monoplane was completed re- cently by Edward F. Allen, a test pilot of Washington, D. C., who recently attained in it a height of 1800 feet. Monoplane and Flies to Experts believe that one of the next important steps in aviation will be a small, inexpensive plane that can be kept in a garage and flown from a yard. This little plane is a distinct advance toward Height of 1800 Feet that goal. It is equipped with a nine- horsepower motorcycle engine and weighs only 205 pounds, with a wing spread of 27 feet. It can make 63 miles an hour. Edward F. Allen, wartime test pilot for the U.S. Army Air Service, in the cockpit of the baby monoplane of his own construction san eee gene eer ater nntnt nt OPE aN res = pecs Ws eS ee ene ae

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February, 1935 A Dozen and One New Ingenious Inventions and Automatic Machines POPULAR SCIENCE MONTHLY Pencil Clip Is Knife A little pocket device that will be found convenient for many office uses serves as a clip to hold the pencil in the pocket; and as a keen two. edged knife for sharp. ening pencils, cutting string, or erasing ink, It answers the purposes of a pocket-knife be. sides serving as a pen or lead-pencil clip Seals Letters Automatically Driven by electricity, this machine stamps and sealsletters. The letters are fed in at é the left and deposited f in the receiving rack Ten Stamps in One Ten different stamps of from one, two, three lines each are available in this metal _ self-inking device Phone Lock With a padlock holding down the Opens Cartons in Three Strokes receiver hook, as 7 : shown at right, the Three motions with a new carton cutter open fiber business man can or corrugated pasteboard boxes quickly. A sharp prevent his tele- cutting blade projecting from the tool is so snaped phone from being that it readily adjusts itself to the edge of the box used in his absence Pencil Calculator A calculator that can be slipped on any pencil (at right) is operated by twisting a small handle. Results are shown in figures through a slot in a revolving collar Typewriter-Punch By means of electrical con- nections from the numeral keys of a typewriter to a power punch, the machine at & the left enables a typist to A punch tabulating cards, thus, dispensing with an_ extra’ operator for the punch

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s Knife levice that convenient Ises serves » hold the 1e pocket, keen two- for sharp. ls, cutting rasing ink, 1€ purposes t-knife be- ng as a ‘pencil clip February, 1925 Ideas for Busy Offices Designed to Save Valuable Time and Labor POPULAR SCIENCE MONTHLY 69 Motor-Driven Eraser In drafting or other work that requires much erasing, an electric power eraser will be found conve- nient. The complete unit, consisting of motor and _— eraser, weighs less than two pounds. It is said to be able to remove a period without touch- ing surrounding copy. Correct pressure for erasing is obtained without the possibility of rubbing through 44139499949898 #aagsaasaass A Convenient Locker An economical new type of metal locker is said to provide storage for workers’ hats and coats in half the space usually required. A small compartment at the top is for hats and small packages, lunchbox, or a book Pocket Check Protector A checkbook with its own check protector attached inside the cover contains checks that have specially treated, semi-transparent “windows.” These are placed over movable rows of raised numerals that can be arranged in the desired combination. A lock- ing device then is lowered on the check and a roller is pushed across the window, making an indelible impression of the amount Handy Eraser in Pencil Form - A Compact Posting Desk For keeping a large number of record cards in a small space, under fire protec- tion, this posting ledger desk recently was designed. It concentrates from 8000 to 15,000 cards within easy reach of one posting clerk, A mov- able tray that slides on tracks abovethecard trays provides a handy surface for writing An ingenious new eraser is made on the prin- ciple of the familiar paper-wound pencil. When the eraser point is worn down, un- winding one of the notched paper spirals “® of the pencil exposes a new erasing surface For Adding Fractions The calculating device shown at the right is a fractional adding machine designed for use where fractional numbers are encountered often, as in architectural and _ engi- neering work. It adds feet, inches and fractions of inches, always reducing them to their simplest form and with the results instantly visible. The in- strument, containing four dials, is operated by the use of a steel stylus

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POPULAR SCIENCE MONTHLY February, 1925 Automobile Ferries Relieve Traffic Jam on Hudson NTIL the vehicular tunnel now under construction under the Hudson River is completed, all automobiles passing between New York and New Jersey have to be carried across the river on ferries. Wood Model of Locomotive in Banquet Hall O PROVIDE appropriate decoration for a banquet of railroad officials in the Chateau Frontenac at Quebec, Can- ada, recently, a full size wooden model of‘ a fast passenger locomotive was con- structed and set up in the banquet room. The model represented the locomotive as emerging from the Connaught Tunnel, one of the greatest engineering undertak- ings on the North American continent. The model was an exact replica in even the smallest particulars. Your Questions Answered AS A special service to readers, the Information Department of Popu- LAR SCIENCE MONTHLY will answer all reasonable questions on general science, mechanics, and radio. Write your ques- tions as briefly as possible and inclose a self-addressed stamped envelope. On some days, especially holidays, the line of cars waiting for transportation on the New Jersey side is more than a mile long. To lessen the traffic congestion and en- © Keystone able automobile commuters to get to work on time, a new type of ferry-boat that carries only automobiles has been put in operation. The photograph shows one of these boats carrying a load of cars. ~ §teel Bridge Collapses in Tornado’s Path eS; MAY boast that we have conquered nature, but when a natural force actu- ally demonstrates its power, we often have to admit our- selves beaten. Near Withee, Wis., en- gineersconstructed a footbridge across a river. Made of steel to withstand fire, the force of the current, and the wear of traffic, it should have lasted for centuries. But a tornado came along, and in its path the bridge collapsed as if built of cardboard. Is it any wonder that men Steel footbridge wrecked by a tornado near Withee, Wis. today still have the same fear of these terrible windstorms as did the savages of the dark ages? Schoolhouse Moved Seven Miles by Water ‘TAKING a schoolhouse off dry land, floating it through canal locks, and towing it seven miles across Puget Sound to a new location on an island, was the The schoolhouse passing through locks of Lake Washington Canal unusual feat accomplished recently by a Seattle firm of contractors. The schoolhouse originally was situated on the shores of Lake Washington, adjoin- ing Seattle. With powerful winches and screwjacks op- erated simultane- ously, the building was raised off the ground and skidded on rollers onto a large barge. Two tugs then towed the school through Lake Washington Canal and the locks shown in the illus- tration, to Puget Sound. The school ar- rived undamaged.

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f these savages fer ly by a situated , adjoin- », With winches acks op- nultane- building | off the J} and n rollers ze barge. rs then e school h Lake on Canal > locks the illus- 70 Puget -hool ar- amaged. February, 1925 POPULAR SCIENCE MONTHLY 71 Mammoth New Defense Gun in Public Demonstration HE size of this mammoth coast de- fense gun could not fail to impress the crowds that gathered to watch its demonstration a short time ago at the Army Proving Ground, Aberdeen, Md. The bore of the gun, which is seen plainly in the photograph, is 14 inches, one of the largest in use in America. Contrasting this- great machine with coast defense guns of even a few years ago, one can appreciate the amazing progress made in designing heavy artillery. Wisconsin Youth Drives the Smallest Sedan ; SMALL boy A in Milwaukee, Wis., drives what is said to be the smallest passenger- carrying sedan ever seen on the streets. There is more difference be- tween his car and the Ford coupé beside it than there is between a Ford and a Rolls-Royce. But it actually runs, gets its tires punctured and its engine out of or- der just like bigger The midget sedan and its driver posed beside a Ford cars. America’s Most Active Volcano in Eruption ( ase most recent photograph of Mt. Popocatepetl shows the most active voleanic peak in the North American continent in action. The Aztec name of this strange peak of snow and fire means literally, Smoke Mountain. Located near Puebla, in Mexico, it is sometimes called by tourists who cannot re- member the spell- ing of the real name, the ‘‘ Puebla voleano.”’ It is the second highest summit in Mexico, rising to a height of nearly 18,000 feet, about 4000 feet higher than Pike’s Peak in Col- orado. The last 8000 feet of ascent must be made on foot because of — loose lava and ashes. On the dome, the heat is intense and the reflection of light from the snow is blinding. At the foot of one of its slopes is a vast lava field. Remarkable photograph of Mt. Popocatepetl in action The Loftiest Point Ever Photographed on Earth HIS photograph of the summit of in- vincible Mount Everest was snapped with a small hand camera at an altitude of 28,000 feet, the highest point on earth at which a picture ever has been taken. It was made during the ill-fated attempt last year to scale the summit of the world’s highest peak. Colonel E. F. Norton, leader of the expedition, is seen at the left center. He was only 80 feet away from the camera, but it took him an hour to negotiate this distance because of extreme exhaustion and difficult footing. The cone-shaped peak appears in the distance. It is only 300 yards away.

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POPULAR SCIENCE MONTHLY February, ms The Wilson Dam at Muscle Shoals ‘TSS magnificent new photograph of the Wilson Dam at Muscle Shoals shows the full breadth of the immense project by which the world’s greatest power dam will create the ‘‘ Niagara of the South.” The dam is nearly a mile long and 102 feet high, and when completed will harness the Tennessee River to sup-- ply turbines capable of generating 600,000 horsepower. Construction of the Wilson Dam was started during the World War to supply: Harnessing the Small Streams for Power BpaeiD strides are being made toward successfully utilizing the power that may be derived from small streams. Two of the newest machines designed for this purpose are shown in these pictures. The device in the upper illustration may be operated from nothing larger than a spillway. It is a complete power unit in itself, consisting of turbine, generator, and governor housed in one cylindrical metal covering. It is of the high speed propeller type, running up to 1700 revo- lutions a minute. The runner shaft is connected with a direct current, 125-volt generator, permitting its use for standard lights, and general farm use. The feature of this machine is the self- contained governor that controls the speed by regulating the amount of water entering. The second machine shown below may be built to suit the conditions of any stream, its designers claim. It consists of a multiple crankshaft, including five or more cranks connected with paddles that operate the cranks when the water strikes against them. Any number of units may be employed. For irrigation purposes a pressure pump is added that allows the water to be lifted for distribution over wide areas. Two types of power units for small streams—A turbine generator (above) and paddle system A Perilous Job—Painting the Brooklyn Bridge (eee Brooklyn Bridge its annual coat of paint is a job full of peril for’ the men who must cling like spiders to the giant steel web. As long as the great’ bridge stretches across the East River, ' connecting the Island of Manhattan with Brooklyn, painters will have to risk their lives once a year to prevent the cables! from rusting. The photograph was taken by a dare-? devil photographer from one of the high’ towers on the bridge. The view of the street cars crossing on the bridge below | gives an idea of the dizzy height from ‘ which the camera was snapped. What Do You Want to Know? OPULAR SCIENCE MONTHLY will be glad to answer questions from } readers on subjects of general science, mechanics and radio. tions to the Information Department, POPULAR SCIENCE MONTHLY, 250 Fourth Avenue, New York City, inclosing a self- } addressed stamped envelope. Address your ques- 5 ; i = ~*~ eH he me -. iat ee an ee

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10,000 n was supply: ing | » ‘ innual ril for’ to the’ great ’ River, | 1 with : : their cables dare-? . high ’ of the below from | ow? *“HLY 3 from } “ience, ques- 5 ment, * ‘ourth:; a self- } February, 1925 POPUEAR SCIENCE. MONTHLY 73 —A Future “Niagara of the South” power for a great nitrate plant for the manufacture of explosives. When it was one-third completed at a cost of $17,- 000,000, work on it ceased. Its comple- tion will mean that the Southern States will have a water power plant second only to Niagara, and one of the greatest agri- cultural and industrial areas in the United Courtesy Engineering View Service States. It also may make possible the peacetime operation of a fertilizer plant that may revolutionize farming in the South and East. How Everest Climbers Bridged ‘Treacherous Chasms A THE highest altitudes ever reached on earth, members of the recent Mount Everest Expedition crept across crevasses of inconceivable depth on the rungs of a portable ladder. Of the many unusual bridges in the world there is prob- ably none possessing strength as great for its weight as the remarkable ladder bridge carried by those daring explorers. The bridge was made specially by an ‘\English firm for use at an altitude of 24,000 feet and upward. In view of the difficulties of transport at this tremendous height, it was essential that it should be extremely light and easily carried. To meet these requirements it was con- structed of hollow wooden spars, put together with hinges in three sections, each of which could be used as a separate iti ae Y ¢-———_ LENGTH OVER ALL WEIGHT How the remarkably light portable bridge was used to cross treacherous chasms. unit. Extended full length the bridge measured 18 feet and weighed only 45 pounds. . Adjustable spreaders of hollow spar were provided at each end of the bridge to give a firm resting surface in the snow or ice, while a light hollow derrick was used to lower the structure safely across achasm. The walls of the hollow bridge rails were barely one-quarter of an inch thick, while those of the rungs were not more than three-sixteenths of an inch thick. Stretched at full length, the bridge could support two fully equipped climb- ers, and when used in an upright position as a ladder, each rung was strong enough to support a concentrated weight of 300 pounds. This great strength was due to a ARBAB the direction of the grain and the system of layers of wood of which the hollow sticks were made. The same principle is being applied in the construction of hol- low spars for racing yachts and for air- planes. Spruce wood is sawed into planks less than one-quarter inch thick, then bent around steam-heated mandrels to the form of cylinders. The bent planks then are built in the requisite number of layers round a wooden core and the layers glued together with water-tight glue. When the core is withdrawn, there re- mains a hollow spar that is far superior in strength and weather-resisting properties to a solid stick. Proportioned correctly, a hollow spar of one-third the weight is as strong as a solid spar of the same size. HOW STRINGER 1S. BUILT UP: OOM OF. 4 vat te WALLIG IN. \ - THICK BLOCK TWO PLY | The insets show construction and operation Pee 5 ee ee 4 aes eine Soh hich TES

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74 POPULAR SCIENCE MONTHLY February, 1925 What Inventors Are Adding | 1 Many New and Useful Accessories Are Designed to Save I A new tire gage of the dial This automatic carburetor Ai type, resembling a watch, control, operating on the de has a curved neck that per- thermostatic principle, turns bi mits easy access to the valve down the needle valve as the fl stem on all types of wheels. engine warms up, thus effect- , to The crystal of this new pres- ing a saving in gasoline. The : of sure gage is non-breakable device is attached easily . Ls Smoking in comfort while driving is pos- sible with this extension tube device. The cigarette holder has a suction cap that fastens it to the outside of the windshield When the motorist shuts off his engine, the steering-wheel is locked instantly by this new automatic device attached below the steering- post. Akey is required to unlock it A combination anti-glare shield and rear-view mirror, attached above the windshield is of semi- transparent material. Swung up- ward against a dark background, it serves as a looking-glass H m in ri th ry S me A new safety crank is equipped with a ratchet that pre- vents the ‘“kick- . eae ee . back” that some- Mounting the spare tire is accomplished times causes injury with a new self-mounting carrier simply by pulling a handle. A catch holds the wheel in place when lift is completed This electric wind- shield wiper is driven by a small motor that is attached above the windshield A balloon tire gage of the projecting piston type is de- signed with the nipple at the side, allowing greater clear- ance while testing air pressure To detect auto-engine noises, a newly invented stethoscope is so_ sensitive that any irregularities in the ticking of a watch can be heard very plainly

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ALP r ie ie t- his ced atic ng- k it owly itive February, 1925 POPULAR SCIENCE MONTHLY 75 to the Motorists’ Enjoyment Labor and Make Your Car More Efficient and Convenient Adjustable calipers have been devised to determine whether balloon tires are properly in- flated. The calipers are set to the width to which a tire of a given size should bulge under a given normal load A small red light strapped to the back of the driver’s signaling hand is a new aid in preventing night driving accidents. It is held by rubber cords around wrist and middle finger as shown A portable electric hoist for autos. Through a system of gears operated by a half-horsepower motor, a platform to which the car is hooked is moved on double or single vertical steel posts eye et wide ee This special jack for cars equipped with balloon tires has the excep- tional lift of 17 inches. A 36-inch folding handle makes it easy to operate. It is the two-screw type Here is an unusual new type of auto- mobile wheel containing a huge inner tube that extends beyond the rim so that half of it is inclosed between the two metal disks that form the wheel. The illustration above shows how the tire is inflated from the center of the disk f): An ingenious folding lunch outfit for ae the tourist or camper combines a food ae Tent, camp bed, cooking out- container, table, and two benches that fit, suitcases and blankets for will seat four persons, as shown above. two can be carried in this compact kit on The entire outfit, when folded, rides the runningboard of a car. The roll and easily on the runningboard, as shown suitcases are fastened firmly by strips of in the photograph at the left metal bolted to the runningboard and clamped together above the blanket roll

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76 How Frozen Eggs OREthan & fifty million [| pounds of canned frozen eggs are used annually in the United States by restaurants, hotels, and in home cooking. They cost from three to five cents a pound less than unshelled eggs and are more easily handled. The first process in egg canning is chilling the eggs in a room at a tem- perature of 31° F. for from 12 to 24 hours. This stif- fens the whites and makes it easier to separate the whites from the yolks. Girls then can- dle the eggs to detect and remove bad or moldy ones. Each girl candles, on an average, 900 dozen aday. Egg canning is done from the middle of March until the middle of September. From the candlers the eggs pass to the breakers, who open and separate them if desired. Canned eggs are sold in the form of whites only, yolks only, or mixed whites and yolks. If no musty eggs are discovered, they then are packed in wax 5 Are Canned for the Market POPULAR SCIENCE MONTHLY Separating the yolks from the whites preparatory to freezing lined cans and sent to the freezing room, where they remain for 72 hours at from zero to four degrees below zero tempera- ture. The entire process, from the breaking of the egg until it reaches the freezing room, takes only eight minutes. The last step is wrapping the frozen eggs in heavy paper and placing them in refrigerator cars, in which they start on their journey to all parts of the world. Study of Fossils Reveals Oil Deposits penis of tiny shellfish and other fossils believed to be from five million to twenty million years old, are being used to assist in locating fields of buried minerals and oils. Experts studying areas of ground, looking for traces of oil, collect these tiny fossils, some of which are so small that they must be picked up with camel’s-hair Spraying fossil shell for the microscope brushes, and send them to the labora- tories of the U. S. Geological Survey in Washington for classification. The fossils are reproduced in photographs enlarged from 25 to 150 times, so that their char- acteristics may be recognized easily. Fossils millions of years old often are marked very faintly. A blowpipe is used to spray white liquid over these shells to make the almost invisible markings stand out under the microscope. February, 1925 Ship’s Blocks Are Tested in Forest Laboratory Ts Forest Products Laboratory at Madison, Wis., has begun a series of tests to determine the strength of kee] blocks used to support the hulls of ships while in drydock. When these kee] blocks fail, the hull drops with the shat- tered timbers and is damaged, usually very seriously, so that the importance of the keel blocks is easily seen. These blocks are 14-by-14-inch timbers of clear white oak. The tests of five sample keel blocks were made under a giant column-testing machine with the load transmitted to the top of the blocks by a roller bearing, so as to allow the timbers to keel over sideways as they would in falling beneath a ship. Before testing, these timbers were sub- merged in water for a week so that they would be tested under conditions similar to those they would encounter in actual service in the drydock. The illustration below shows a number of the _ blocks under tremendous downward pressure in the laboratory column-testing machine. Keel blocks under tests in laboratory Astronomy now Taught by Mechanical Model uae can we see only one side of the moon? What causes eclipses of the moon and sun? When will there be another eclipse of the sun? What causes the seasons? sented, so that by merely turning a handle the studerit can see for himself the things that sound so complicated in textbooks. Questions like these can be an- swered readily and with extraordinary clearness by means of a -efascinating model of the sun, moon and earth completed recently in England for use in schools and col- leges. The relative sizes of the three bodies, and their motions, showing their positions in respect to each other on every day of the year are accurately repre- This model shows the relative courses of sun, moon, and earth

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rth February, 1925 Watchmakers Must Pass Rigid Examinations O MAKE sure that all jewelers dis- playing watchmaker’s signs in their shops are really experts in their trade, the U. S. Horological Institute conducts ex- aminations of all applicants before issuing licenses by carefully examining samples sent in as a preliminary test of skill on the part of the applicant. To keep the public from being imposed upon by incompetent men, the examina- tion consists of two parts. The first part is a written examination in which the ap- plicants are expected to show their theoretical knowledge of watches. For the second part a damaged watch is sent to the applicant. This he must repair to the best of his ability. These test watches previously have been put out of order by the institute so that the repair work may easily be graded. The photograph shows R. E. Gould of the Horological Institute, checking up on repair tests by an electrical timing device. Testing the accuracy of repaired watches POPULAR SCIENCE MONTHLY 77 Blended Motor Fuels Are Bat to the Test ret |suPALy 7 3 me ER TACHOMETER COOLING WATER. > TEMPERATURE, INDICATOR >: * FUEL 'LI NETO | CARBURETOR THROTTLE CONTROL M. A. Thorne of the Bureau of Standards, testing blended gasoline with the new apparatus O MANY blended fuels are on the market now that the average motorist is puzzled as to which to choose. Nearly every time he drives up to a new filling station, a new mixture is recommended to him and he has no way of telling which ones are good and which ones poor. Among the advantages claimed for most of these special fuels are increased mile- age, more power, prevention of carbon formation, and elimination of knocking. Coming to the motorist’s assistance, the U. S. Bureau of Standards recently has developed a method of testing these special fuels to determine whether they are better than ordinary commercial gasoline in regard to economy, power, and prevention of irritating knocking. In the photograph M. A. Thorne of the Bureau of Standards is seen with the new testing apparatus. He has a small, high-compression gasoline engine at- tached to an electric dynamometer, which is used first as a motor to crank the © engine. After the engine is started, the dynamometer is used as a generator and the engine speed is controlled by varying the electrical load. The power developed by the engine is computed from readings of a spring bal- ance applied at the end of a torque arm, Fuel economy is determined by a fuel- metering device consisting of a series of burettes, or tubes graduated to scale. Electrical Machine Records Heart Energy a on the theory that the human heart generates small electric cur- rents, a new machine for recording heart action was tested recently at the Ellis Hospital in Schenectady, N. Y. The instrument measures the difference in voltage between various parts of the body, and is actuated by energy that Seeks New Cures by Means of Radio Waves ‘2 HIS laboratory at Alpine, N. J., Dr. J. Clawson Burnett has been per- fecting the oscilloclast, an instrument designed to heal human diseases by means of electro- e he 4 si magnetic waves. After experi- menting for two years with the ma- chine, the inven- tion of the late Dr. Albert Abrams of California, which raised a storm of criticism,’ Doctor Burnett says he is now ready to place his results before scientific societies for examination. Just as radio- phones respond to electromagnetic waves, so may the human body be affected, according Dr. J. Clawson-Burnett (right) at work in his laboratory to Doctor Burnett. comes from the patient in the form of tiny electric impulses. This energy is so small that for detection it must be am- plified much as a radio wave is amplified, The instrument that measures heart action 2 NADL BSE Re Saks PERE SS PLU SS oe

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I erg ptr a ane nr cts ee . — 78 POPULAR SCIENCE MONTHLY Artificial Heat OW Dries Hay Crops

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o\AKE hay while thé sun shines,” urges the old proverb. But what shall the unlucky farmer do if the capri- cious sun refuses to lend its assistance during the haying season? Thousands of acres of crops are lost every year on ac- count of rainy weather at the critical period. In England, where damp and foggy weather, common during certain seasons, makes a good hay crop rare, a new device recently has been patented by Captain B. J. Owen, which dries hay by means of artificial heat. The hay is stacked while it is green and then it is dried in 25-ton stacks. The photograph shows the system of pumping and drying. Heat is conducted through a large pipe to the interior of the stack.

A Portable Power Hammer for Light Work Fok lighter grades of work, such as sewer jobs and small trenches where light timber or steel sheeting is employed, the big automatic hammer is practically useless. For these jobs a new hammer much reduced in size is convenient and economical. It can be used in close quarters, needing only half an inch clearance. It embodies all of the features of the large hammers and is carried about easily. The photo- graph shows the hammer in use for driving light sheeting for a trench.

To Produce More Helium ‘THE U.S. Navy Department soon will begin developing additional supplies of helium gas for airships, it is announced. At the present rate of helium production in the United States, it would require four months to obtain enough of the gas to fill the bag of the dirigible Los Angeles, formerly the ZR-3. In developing helium and constructing a plant for its extraction, Uncle Sam already has spent more than $5,000,000. February, 1925

Mechanical tnctansiar Combines Five Machines ve complete woodworking machines with all adjustments are combined in this unusually compact mechanical cabinetmaker. It includes a sawtable, jointer, thickness planer, boring table, and speed spindle. In the photograph above three opera- tions are shown—ripping, thickness plan- ing, and hollow-chisel mortising. Almost every woodworking operation— 20 entirely different and practical ones— are said to be performed on this machine, which can be used on both long, heavy work and small, accurate work. Four men can work on the machine at the same time. The stability of the machine for group work makes it especially valuable in manual-training classes. The machine is of strong construction. It is equipped with a one-horsepower motor, and takes only 28 by 41 inches of floor space.

See if you can score 100 per cent.

How Much Science Do You Know? ‘ier man who has stored in the back of his head a working knowledge of the fundamental facts of science possesses an important asset in these days of scientific achievement, whatever his work may be. For that reason POPULAR SCIENCE MONTHLY publishes each month a list of a dozen questions about scientific facts. will help test your knowledge, but will afford you real entertainment. Answer the 12 questions below to the best of your ability, then turn to page 157 for the correct answers, and see how nearly you were right. 1. Why do some people get bald? 2. Does the boiling of water remove impurities in it? 3. What is the lightest substance known? 4. Why does a snowflake fall more slowly than a raindrop? 5. Why do we believe that all stars are moving? 6. Which travels faster, electricity or light? 7. Do insects have brains like ours? 8. Why does radio go through walls? 9. Are there special brain foods? 10. Why can parrots talk? 11. If the air weighs 15 pounds to the square inch, why does it not press us flat? 12. What makes the spouting geysers in Yellowstone Park? These questions not only

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1S al e, e, le Swe nperee es, | February, 1925 POPULAR SCIENCE MONTHLY 79 Mechanical Merry-Go-Round and See-Saw for Children AROUND they go on their merry-go- round, and up and down on their see-saws, for the ingenious new mechanical plaything seen in the photograph is a combination of the two amusements. As it teeters, it revolves—this ‘‘merry-go- bob,” which seems sure to find favor with children who like to make things go by their own efforts. The play machine is substantially made of iron and will not tip over. The children make it go by pushing on pedals and pull- ing handles. The plaything can be used in the nursery as well as on the lawn. Four children need to cooperate to run the merry-go- bob, but it is safe to say that its opera- tion need not cease on account of lack of passengers, at least if the plaything is standing in plain sight of the chil- dren somewhere out of doors. Flaws in Big Guns Are Revealed by X-Ray HE use of a newly devised X-ray testing apparatus soon may make it possible to detect flaws in large guns and other ordnance, which, if not found, might cause disastrous explosions such as have occurred in the past. This was the recent statement of Col. T. C. Dickson, of the Ordnance Department of the U. S. Army, speaking before the American Society of Mechanical Engineers. A 280,000-volt X-ray equipment has been put into operation in the laboratories of the Watertown, Mass., Arsenal. With this apparatus clear films of steel up to three inches in thickness can be obtained, according to Colonel Dickson, but so far there has been little success with steel more than three inches thick. ‘*The experience with the equipment,” he said, ‘‘has demonstrated that it has great practical value in showing methods by which sound steel castings can be pro- duced, and as an instrument of inspection. ‘The removal of all defects, or their location where they do harm, makes pos- sible a material saving in the weight of castings. The cost of making X-ray films of castings is far less than the cost of cut- ting up castings to ascertain their sound- Starting troubles, which come regu- larly with zero temperatures, can be lessened by a few simple precautions. In winter the main resistance to cranking is the stiffened, chilled oil film on the cylinder walls. If you keep your car in a cold garage, add warm water to the engine jackets. This will heat the oil film on the cylinder walls and give a cranking speed sufficiently high for starting. At zero the capacity of the battery is only about half of that at summer temperatures, and the voltage drops very low with large current drains. During the winter much greater de- mands are made on the battery. Start- ing requires a much larger current, the lights are burned longer, and few long trips are made that might keep the battery charged. Test your battery frequently during the winter, there- K Know ‘Your Car SSS, 5p yqyy,(( HQ fore, and if it is much below the charged condition, have it charged from an outside source. Gasoline cannot be ignited until it is in a vaporized state, and at low tem- peratures it vaporizes slowly. Hasten this ignition by turning the engine over a few times, with the carburetor choke closed, then allow the engine to stand for two or three minutes before using the starter again. This wait allows the gasoline to continue vaporizing in the cylinder until an explosive mix- ture is obtained. Hot water poured over the carburetor and intake mani- fold helps also to vaporize the gasoline more quickly. It is well to carry a thermos bottle of boiling water in the car for this purpose. After the engine is started, conserve its heat by using a radiator shutter, and, in very cold weather a hood cover. New Type of Windmill Runs without a Vane WO South Africans, Messrs. Oohlson and Henning, are the inventors of this new type of vaneless windmill de- signed so that its sails will operate and drive the pump rod without shifting their direction according to the direction of the wind. Two semicircular sails are arranged at right angles to each other in such a way that a surface always is pre- sented to the wind. The inventors are shown with their creation, the cost of which is said to have been less than $50. The height of the windmill is 20 feet. It is geared in a ratio of five to one and is so powerful that two men of average weight can hang on the driving rod with- out -impeding the work of the mill. The home of the inventors is Port Elizabeth.

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CEE =i Ache i lcha sasadgeaha agente anatase aaneeenameemmnmmeemenee abeeninnasetnemeasemtrt taker — POPULAR SCIENCE MONTHLY February, 1925 New Inventions to Lighten Here Are 16 Useful Mechanical Utensils and This light electric iron for shaping hats can be used with a handle, or clamped in a sta- tionary base A handle that will not get hot and ter- minals that will not burn out are advan- tages claimed for this electric iron. Ven- tilation at the back and around the handle attachment prevents excessive heat This new cake- pan has two re- movable bot- toms, a flat one for layer cakes, and one with a tubular center for angel food ee eal Sprung into the mouth of the milk pitcher and turned to engage a notch, this strainer lid protects the contents from dirt and flies A collapsible oven, small , enough when folded to fit in a suitcase, is useful for the camper, or convenient in the smallest kitchenette Although small enough to be placed on a shelf, the com- pact electric range shown at the left has ample capacity to do every sort of cooking for a family of five. At the top is a “quick boil” heater. The oven may be used also as a fireless cooker A mechanism that tilts and rolls the tub, sending the suds whirling swiftly around in three complete figure-eight move- ments, producing unusual friction be- tween the clothes and water, is a feature ' of the new electric washer shown above When not in use; the electric’ sew- ing machine pic- tured below __§is concealed in an ornamental table. If a door is opened at the front, the table becomes a convenient writ- ing-desk, with compartments for paper and pens

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nd ye- ye- ire ‘| ve use, sew- pic- . an able. ened , the es a writ- with ‘s for February, 1925 the Drudgery of Housework Electrical Appliances to Save Time and Labor Washing and wipinz windows may be ac- complished in a single operation by using the newly patented window- cleaning brush shown above. A narrow strip of hard rubber for wiping is attached to the same handle as the brush, fol- lowing it across the sur- face of the window Caring for wax floors becomes less of a drudg- ery with the sliding combina- tion waxer, pol- isher and brusher _ pic- tured below. It is about the weight of a car- pet sweeper A completely equipped, odorless kitchenette, resembles a_ neat chest of drawers when closed, man who appeal to the wo- to keep house in limited quarters POPULAR SCIENCE MONTHLY $i / Lifting the handles at the / — sides of a new pressure kettle releases the top from the bottom automatically. The bottom can be used also as a small oven a oe A four-bladed chopper with knives radiating from the center facilitates chop- j ping’ meat or vegetables The grinding wheels of this all-purpose house- hold tool can be used to sharpen knives, scis- sors, the lawn-mower, or any other edged tools. Other ingenious parts of the device make it - useful as a can- and bottle-opener, or glass-cutter A fork and spoon are hinged together in this utensil to form a handy salad tongs. They can be used separ- ately, if desired, for the hinge may be released easily whenever it is necessary Here is a combination egg-beater, cake- mixer, jam-strainer and flour-sifter—a compact utensil for all these purposes which should has

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Stee dat Bogue safes eI ee. POPULAR SCIENCE MONTHLY

SIGNAL FROM LANDS END

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SHIPS HEAD February, 1925

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DIRECTION FINDING GEAR INALINER How Wireless Is Used to Steer Vessels into Port N ILLUSTRATED article in the December issue of POPULAR SCIENCE MONTHLY described an amazing new use for Marconi’s system of reflected beam radio transmission—the “radio lighthouse” which, in recent tests, has proved successful in guiding ships through heavy fogs. The illustrations above show the appara- tus that enables the ship pilot to get his bearings by these radio -signals from shore. The top picture represents a steamer being guided through the English Channel by them. Four aerials on the ship receive signals from every direction. The aerial on which the sound comes in loudest is the one nearest the transmitting station. On receipt of the signal, the operator determines, by the direction-finding instrument, its exact direc- tion. This is sent to the navigating officer who, manipulating the dials of an indicator, finds out the true bearing of the ship,

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sarest of the y the direc- officer cator, February, 1925 Your | Dials tuning a radio set that come with experience and knowledge of the set itself, but that can be acquired by any novice without great difficulty. In this article I shall outline the best methods of tuning for each of the basic systems of reception in general use. Owing to the diversity of types of receivers, there will be a few variations that cannot possibly be covered, but the procedure that I To are certain little knacks in shall describe will give you, I hope,’ sufficient information to act as a guide to the most satisfactory results. The majority of crystal receivers em- ploy either galena, or some synthetic substance very much like it. The actual adjustment of the crystal, therefore, is identical in all cases. Receivers using a crystal alone, without vacuum tubes, are at once the simplest and most difficult to tune. This sounds paradoxical, but is true. In a large number of cases there is only one dial on the set, and in the majority not 600 more than two. These are extremely simple to adjust, because a station will be heard over a large number of the degree marks on the 500 dials. This part of the tun- ing consequently is simple. The difficult thing is to tune out an interfering station, whenever one is heard. 8 450 pein RE proceeding fur- 350 ther I am going to lay down a very imperative rule—one that applies to every type of radio receiver and to every operator. In 250 turning any dial on your set, move it as if the whole 200 world depended upon the 0 slightest fraction of space between each of the degree marks on the edge of the dial. In other words, move it as slowly as you possibly can. For good results there is no variation to this rule. Before signals can be re- ceived on a crystal set, the delicate little wire, often called the ‘‘catwhisker,”’ WAVE LENGTH IN METERS 300 which touches the glistening surface of the crystal must be in the right position, and it must rest on the surface “‘sensitive spots.” POPULAR SCIENCE MONTHLY to Tune Your Set for Best Results By Jack Binns 4 America’s Most 12 Popular Writer on Radio as lightly as possible. Experience will show that there are a few spots that give much louder response in the tele- phones than the rest of the surface of the crystal. These places are known as the Once one of these has been found, the crystal should be let alone until some accidental jar or shock knocks the wire off that particular spot, when a readjustment will be necessary. In doing so, move the wire very carefully and do not press it down. If you happen to have a crystal set with a dial marked “‘coupling,’’ keep this in the minimum position if you experience interference. If you have no such dial, and still get interference, then my advice is to shorten the length of your antenna. Remember that the maximum effective range is 50 miles. Do not try to reach out with your set by putting up a long an- tenna. Be content to get good clear re- CALIBRATION CURVE 20 8630 40 50 60 70 SETTING FOR No. 2 DIAL A Quick and Easy Way to Dial Broadcasting Stations On a sheet of paper ruled in squares, number the vertical lines from left to right to correspond with dial settings, from 0 to 100, as shown. Then, at the left side, number the horizontal lines for wave lengths, reading upward from 200 to 600. On the right side number the same lines for frequencies in kilocycles, reading downward from 500 to 1500. Now tune in five or six stations on your set, and note the dial reading for each. Then on the chart where the vertical line corresponding to each reading would intersect the sible; but usually you will find that horizontal line corresponding to the Keys to ie 80 90 wave length or frequency of the sta- tion, make a dot. When you have done this for each station, connect the dots with aline. This will give you a calibration curve, by which you can locate any other desired station on your dial simply by noting where the wave-length line for that station inter- sects your curve. The vertical line at this intersection gives you the dial reading. Of course, since the lines represent round numbers only a close approximation of the settings-is pos- this chart will be amply sufficient 83 ception from your local stations with a minimum of interference. The owner of a regenerative set owes it to the other radio fans to move his dials carefully. The regenerative receiver, properly constructed, is selective and sensitive. When poorly operated, how- ever, it is a fairly powerful transmitter, and as such will cause interference to others. Moreover, when it is in a trans- mitting condition it is absolutely useless as a receiver, for it is uncontrollable. There is a large variety of regenerative receivers, from a technical point of view. In addition, there are several different ways in which the control dials are marked. Invariably, however, they will fall within two groups: First, dials marked “‘ Tuning,” “‘Selector,’’ or “‘ Wave- length,” for tuning in the desired station; second, dials marked ‘“ Regeneration,” | “Intensity,” or ‘‘ Volume,” for controlling regeneration or the in- tensity of the signal. Do not, under any cir- 500 cumstances, tune this type of receiver so that you get a sharp whistle of varied 545 pitch. This is a sign that your set has ceased its 600 » proper function of receiving, z and has transformed itself 666 S into a transmitter. In that = condition it is of no value to a you or any one else. 750 = > | esse you turn your 857 5 set on, either with a & battery switch, or by the sie = little dials marked “ Rheo- stat,’’ set the regeneration dial at zero. Now tune with 1200 the dial that controls the wave length. Move the 1500 dial slowly until a station is 100 heard. Then turn the re- generation or volume dial slowly up from zero. As you do so you will observe that the signals become stronger and stronger until finally they reach a point where they begin to sound mushy and blurred. Stop imme- diately and go back to the point just before they began to distort. Or, better yet, turn down the detector tube with the rheostat dial until the mushiness disappears. This method prolongs the

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life of the tube. Now advance the in- tensity dial again to the point where you get maximum signal strength without any distortion. a baie you have tuned your set so that you can enjoy the broadcasting without disturbing your neighbor. Make a record of the settings of both dials so that you can tune in the station again when you want to listen to it. After a little practice you will be able to change from one wave length to another with a hand always on each dial so that you can keep your receiver from oscillating and yet have it adjusted so that it will be sen- sitive and selective. You will find that as the battery that lights the vacuum tubes gets old or dis- charged, it will be necessary to increase the rheostat dial reading lightly. When a new or recharged battery is put into use, turn the rheostat down again. The methods for tuning a reflex set apply to the six- tube portable radio-frequency. sets and similar receivers. These types are oper- ated under the same general principles — the only difference being that in re- flex sets. certain tubes are ar- ranged to do double duty. In some of the reflex sets, an —addi- ‘tional element of tuning is intro- duced through the use of a crys- tal detector. The majority of receivers of the types men- tioned above em- ploy a loop of wire in place of the usual aerial and ground con- nections. For these the opera- tors must have a fair knowledge of the compass points about their homes. With this knowledge they will find the following little tip of much value in tuning in dis- tant stations, because it is very necessary that the edge of the loop be pointed directly toward the station they desire to hear. 6 mer a map of the country. On it spot your location. On most maps you will find an arrow at the top indicat- ing north. Now get a little pocket com- pass and lay it on the map so that its needle points in the same direction as the arrow on the map. It then will be an easy matter to find the exact direction of -the different stations within range of the set. When searching for one of these sta- tions, the first thing to do is to turn the loop so that its edge points in the right direction. Tuning the receiver to its correct wave length will follow after. How to Set Your Loop Aerial On a inap of the United States spot your location. Then place a pocket compass on the map and adjust so that the compass needle points in the same direction as the arrow on the map indicating “‘north.”’ It will then be easy to turn the edge of the loop in the direction of the broadcasting station you want to hear POPULAR SCIENCE MONTHLY Most reflex sets have the following dials: One marked ‘‘Tuning”’ or ‘‘ Wave length,” another marked “Vernier,” a third marked “ Rheostat,’’ and a fourth marked ‘‘Potentiometer” or ‘ Volume.” Where a crystal is employed, make sure that the delicate wire is resting on the sur- face of the crystal in the manner de- scribed under the directions for operating a crystal set. As soon as the rheostat, or battery switch, has been turned on, it will be ob- served that there is a grinding noise in the loudspeaker if the potentiometer dial happens to be all

the way over to one side—usually the left side. This dial should be changed slowly unti] the noise disappears. Now turn the wave-length dial very slowly until some station is heard. It may be quite pos- sible that the receiver will whistle just as a regenerative receiver does when badly adjusted. In this case a slight adjustment of the potentiometer dial will remedy the trouble. When a station has been brought in, move the dial marked “Vernier” until the signals are loudest and clearest. <A little more adjustment on the potentiometer dial will remove any mush or distortion. As a general rule, this dial should be left in that position, but in bringing in distant stations it may be necessary to advance it a little toward the side that eventually brings on mushi- ness. In all radio receivers, irrespective of type, where vacuum tubes are used, the February, 1925 rheostat dials should be adjusted so that the lights are burning as dimly as possible consistent with clear, undistorted musie or speech. This is a matter of economy to yourself, as well as a controlling factor in the degree of enjoyment you will get out of your set. The majority of neutrodyne receivers have three large dials on the panel, al- though a few this year have only two. The tuning directions, however, apply to both types. In addition to the large dials, there are two or more rheostat dials to control the brilliancy of the tubes, For most veteran radio fans the neu- trodyne set is difficult to tune because there are no familiar noises to guide them. The tuning, however, is simple enough if the following rules are observed. It will be found in most cases that the three dials are almost identical in their settings for any particular station. The best way for the new fan to proceed is as fol- lows: TART with the sec- ond and third dials at the same setting, both at 55, for example. Now move dial No. 1 slowly between 50 and 60. If no signal is heard, move the second and third dials another degree either way, and then move the first dial over 10 degrees. Some station soon will : be heard, and maximum signals can be obtained with slight adjust- ments on all three dials. As soon as the station has been identified by its call letters, paper the figures of each of the three dials at which it was heard. When you desire that station again, just set the dials at those figures, and if the station is on the air and conditions are favorable, it will come in. The procedure in picking up distant stations is exactly the same. ; NCE four or five stations have been located, there is a simple method shown in the chart on page 83 by which new stations can be found without difficulty. This method can be used for any type of set. Like all other sensitive receivers, the neutrodyne will, under certain circum- stances, bring in atmospheric disturb- ances while you are listening to distant stations. If these static disturbances are very bad, they can be counteracted some- what by slightly detuning the third dial either above or below the correct figure. There are two types of super-heterodyne receivers in use. First, the home-built or built-to-order type, which ordinarily employs eight tubes; and, second, the factory-built receiver with six tubes. There is an important technical difference between the eight- and six-tube sets. (Continued on page 159) write down on a piece of:

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February, 1925 POPULAR SCIENCE MONTHLY 85 How to Do Good Soldering The Easiest and Quickest Way to Make By John Carr NE of the main reasons why so O many of the manufacturers of radio parts are fitting their in- struments with solder lugs is because soldering is the easiest, quickest, and best way to make electrical connections. Beginners are inclined to doubt this fact after their first session with a

BONO soldering iron chiefly because they do not know how it should be done. And the matter of proper equipment is vital, for even an expert cannot turn out a good job of soldered wiring if he has not the right material to work with. _ Really, there are just three essentials to good solder work of the kind required in radio construction. They are: A solder- ing copper (often called ‘‘soldering iron,” although it is always made of solid copper) heated to the proper temperature, high grade strip solder, and a paste or other flux that will make the solder flow over and form intimate contact with the sur- faces of the metal parts to be joined. Figure 1 illustrates all the equipment you need. An electrically heated solder- ing copper is not necessary—just as good work can be done with the old style soldering copper, but an electric outfit saves the time that otherwise would be wasted in waiting for the copper to heat up between connections and also eliminates many trips back and forth to the kitchen range. “HERE are several kinds of soldering paste on the market and most of them are excel- lent, but any brand that contains acid should be carefully avoided in elec- trical work because of the danger of short cir- cuits and corroded con- Solder should be made of equal parts of tin and lead, but unfortunately a great deal of solder sold today contains very little tin. Such solder does not flow easily and is difficult to work with. Tin is more expensive than lead, which ac- counts for the lack of it in cheap solder. Be sure that the solder you buy is of the best grade. Another form of solder that is much used in electrical work is the rosin- core solder. It con- Fig. 1. The equip- ment you need for a good soldering job (at left) in- cludes strip solder, paste, pliers, and a soldering copper. The copper shown is electrically heated, but the old style works as well

Fig. 2. Soldering a joint. Hold the ends of the wires together and touch the joint with the drop of solder on the end of the copper

nections. Strip solder is easier to work with than the kind that comes in solid bars, especially for elec- trical work where small coppers ordinarily are used. Bar solder will cool the copper before the solder melts from the end of the bar. ;. not to do it. Fig. 4. Four kinds of soldered joints. The one at the extreme left shows how The second from the left is the joint made in Figs. 2 and 3. The Radio Connections requires a somewhat hotter iron than many of the other fluxes. The type of pliers shown in the illus- tration is not necessarily the best; any pliers that will cut wire and hold it in position while soldering will do. ASSUMING that you have purchased the necessary equipment, the first step is to prepare the copper. This proc- ess is known as “‘tinning.” If the end of the copper is not clean and shiny, it should be made so with a file. It should

Fig. 3. Completing the joint. Hold the end of the copper on the connection until the solder flows into the joint and over the ends of the wires then be heated to the point where it hisses when jabbed into the soldering paste. Stick it in the can of soldering — paste several times and then rub the end with the strip solder until the surface is covered with a smooth coating of solder that closely adheres to the metal. The best test for tinning is to rub the end of the soldering copper on a piece of woolen cloth and if the solder cannot be re- moved, the copper is properly tinned, as shown in Fig. 1. Before you actually start to solder the con- nections in the radio set you have just built, it is a good plan to practice a bit on short lengths of bus wire until you have mastered the knack of it. If you are using solder- ing paste, dip the ends

sists of a small tube of solder filled with rosin, which acts as a flux and eliminates the need for a separate flux or paste. It makes an ideal joint for electrical use, but third and fourth joints show how the wires should be overlapped if they are to be subjected to strain. Notice how neatly the joints can be made with practice of the wires to be joined in the paste. Now melt enough of the solder on the tinned portion of the copper to form a small drop on the end. Next, hold the ends of the wires together, and touch them with the tip of the copper so that the drop of (Continued on page 160)

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Seek vet PP eagen sts) cto eB tnd a a tee Se 7 aa ee a aw gepenncome Land — Se a ee cee ee oe eaters Oe, oor thane 86 POPULAR SCIENCE MONTHLY February, 1925 A Four-Tube Set to Fit Your Phonograph Cabinet How to Build an Economical Receiver of Unusual Tone Quality By Alfred P. ERE is a radio receiving set ar- H ranged so that you can fit it in the record compartment of almost any standard phonograph. And it is a set that is well worth building, because it combines sensitiveness and selectivity with ease of con- trol and the finest possible reproduction of broadcast music and speech. The circuit is the familiar three-coil regenerative tector plus one stage of trans- former-coupled audio- amplification and two stages of resistance- coupled audio-amplifica- tion. . Radio fans who never have tried resistance- coupled amplification will be astonished at the quality of reproduction of this receiver. There is no difference whatever between the first stage and the last stage in the way of tone or clearness, and with 90 volts of B battery, the volume on local stations with four tubes going is too great for most loudspeakers. and these are well covered by the dials. The low-loss idea has been carried out in the design of the detector-circuit wiring and in the elimination of special mount- ings for the coupling condensers, the Lane de- dl tubing. Tuning is simple, for there are only two dials and the control of regener. ation need not be particularly critical except on distant stations. The set also is economical to maintain, because it is not necessary to keep all the tubes going when you are listening to programs from local stations. The use of three switches gives you all the power you need for various condi- tions. The series con- nection of the switches prevents leaving one or two tubes burning in your absence, for the right-hand switch Rl cuts off all the tubes, re- gardless of the position of the two other switches. RHEOSTAT in the filament circuit of each tube makes it pos- sible to operate the tubes at the lowest possible temperature consistent with full volume. The receiver is ar- ranged to use 6-volt storage-battery tubes. of Fig. 1. The door cut in the back of the cabinet. Notice how the B batteries are The construction includes several new wrinkles in wiring and in the elimination of unsightly screws. In fact, there are no screw holes whatever in the front panel S, except those used to support the variable condenser D and the tuning unit: A, B, C, = The four-tube set completed and in- stalled by Mr. Lane in a phonograph cabinet. This is the set he tells you how to build in the accompanying article. It is now in the home ci Robert S. Dietrich, of Brooklyn, N. Y., who is shown tuning it to a distant station V «€ Fig. 3. The symmetrical layout of the front panel, showing wave-length dial (upper right), regeneration dial (upper left), rheostat knobs, jacks, and switches ‘s) Cc H2 GRD. -A +A > S68 45 ANT. DET. AMP 45V. 90-I00V. placed at the back of the set plate resistances, and the grid leaks. The wiring has been reduced to the simplest possible form by the arrangement of the parts in the set and by placing all of the battery and filament wiring under the sub-panel T and incasing it in spaghetti Fig. 2. Wiring diagram showing hook- up for three-coil regenerative detector, plus one stage of transformer-coupled audio-amplification and two stages of re- . sistance-coupled amplification. All parts are lettered to correspond with the illustrations on the opposite page the usual 144-ampere type. Dry-battery tubes of either the 114- or 3-volt type can be used without changing the set, unless you use rheostats that are suitable for only one type of tube, in which case the rheostats will have to be changed. a ee a

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are er- cal 10n the of ble ent rolt |. Of 9 tery can less for the February, 1925 POPULAR SCIENCE MONTHLY 87 The large-capacity con- denser G is included in the circuit so that the A or B battery may be charged by any type of charger without danger of blowing the fuses. THE PARTS YOU WILL NEED A, B, and C—Low-loss tuning unit D—Low-loss variable con- denser, .0005 microfarad E—Grid condenser, .00025 microfarad, with clips for grid leak F—By-pass condenser, .0005 microfarad G—By-pass condenser, .5 mi- crofarad Hi and H2—Coupling con- densers, .012 microfarad (two pairs of .006-microfarad fixed condensers with solder lugs) I — Audio-frequency trans- former Ji, J2, J3, and J4—Standard vacuum-tube sockets K1, K2, K3,and K4—Rheo- stats for 14-ampere, 6-volt tubes L—Grid leak, 2 megohms M—Grid leak, 1 megohm N—Grid leak, .5 megohm O01 and O2—Fixed resistances, 100,000 ohms Pi and P2—Double-circuit jacks Q—Open-circuit jack Ri, R2, and R3—Battery switches S—Panel, 13 by 1414 inches T—Sub-panel, 7 by 13 inches U—Sub-panel, 214 by 4 inches Two brass right-angle brackets, two 4-inch dials, 7 binding posts, 4 tubes, screws, bus-wire, etc. 6% th | a | | 64 | — | e | yi i - Fig. 5. Diagram showing measurements for the panel layout. The measurements for X, Y, and Z may be varied to suit the size of the particular type cabinet you use The tuning unit, A, B, C, ean be bought complete, or you can build it your- self. The primary, A, consists of 6 turns of No. 14 bare copper wire, 4 inches in diameter .and spaced 14 inch between turns. The secondary, B, is 47 turns of No. 16 double-cotton-covered wire wound around 15 pegs set in a 334-inch circle by the around two, skip two method des- scribed in POPULAR SCIENCE MONTHLY for January. HE tickler coil, C, was wound around 15 wooden pegs set into a wooden hub 14% inches in diameter, with 44 turns of No. 20 double-cotton-covered wire. The coils are held in place by clamping be- tween strips of bakelite. Theshaft for the tickler coil, C, is a 14-inch bakelite rod, so that no metal is used in the construction of the tuning unit except the small screws. Any good make of low-loss condenser may be used, but the capacity should be -0005 microfarad if a secondary coil such Fig. 4. Rear view of the complete set (above), showing layout of parts and wiring. All parts are lettered to cor- respond with the wiring diagram on the opposite page. The wiring of the set is unusually simple if the instructions are fol- lowed out carefully the correct value. The front panel of this par- ticular set was made of mahogany-finished bake- lite, but that is a matter of personal choice—any material will do, provided it is stiff enough to hold the entire weight of the set, which is supported on the front panel. "RHE size of the front panel S is 18 by 14% inches, but these dimen- sions can be altered to fit the size of the record com- partment of the phono- graph. Because of this possible variation in the panel size, the spacing of holes in Fig. 5 and the layout for panel S are given from the center lines, and any changes in the panel size should be in dimensions X, Y, and Z. The panel, of course, Fig. 6. Details of the resist- ance coupling, showing how coupling condensers, plate resistances, and grid leaks are arranged compactly on resistance - coupled stages can be made as large as necessary, and if 3-inch dials are used, 1 inch can be subtracted from di- mension X and \% inch from dimensions Y and Z, making a minimum size of 12 by 13 inches. HOW TO BUILD THE RECEIVER After you have pur- chased all the parts, the Fig. 7. Left-hand view as described is used. It is extremely im- portant to use a high quality audio trans- former, since the advantage of resistance coupling is lost if the audio transformer in the first stage produces an appreciable degree of distortion. Any of the standard makes of switches, rheostats, or sockets may be used, but the jacks should be of the type shown in this set, since the frames of the jacks are used to support the sub-panel T. There are a number of makes of this general type. Any make of fixed resistances and grid leaks may be used, provided they are of Fig. 8. Right-hand view first step is to cut the panel S to a size that will fit the record compart- ment of the phonograph cabinet. Now, cut out a paper pattern the exact size of the panel and paste it to the panel with library paste. Measure off the positions of the holes on the paper. Note that only the centers for the shafts are given, because many standard instru- ments are single-hole mounting and the others vary considerably as to the loca- tion of the screws for mounting. After you have the centers of the shafts located, use the paper templet that comes with each instrument requiring mounting (Continued on page 162)

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EG ae re Sb eae Ee Set tere 2) es Saemnageres ganpeueecta ema a ae BPE os erry ia eieaeaanedini atedianeannatidiinedemanamnandeananamnementedaramatineanaetel et 8: 88 POPULAR SCIENCE MONTHLY | How Radio Gyps Duped Me February, 1925 The Story of a Victim Who Built a Set of Junk As Told to Newton Burke S A radio fan, I am no longer a A beginner—at least I have reached a point in my pursuit of the mystery of radio where I find a little less mystery and hear a little more radio. It all began during what might well be called the gold-rush days of* radio, when the craze had obtained its first hold on the imagination of the public. Hordes of newly made radio fans fought madly at every radio-store counter for the small consignments of parts that came in from manufactur- ers buried in a sea of rush orders..: The radio craze first hit me one Saturday afternoon. It all seemed so delightfully easy. All you had to do was to string a wire on the roof, connect some wires to Vari- ous apparently sim- ple electrical instru- ments and, presto! Music would flow into your ears from all over the country. By Monday morr- ing I was firmly de- termined to acquire a radio outfit before another day had passed. As soon as I could, I headed for the nearest radio “I was an easy mark for those gyps. In ex- change for my hard-earned dollars they handed me parts that were almost useless— could find and wasted reams of paper drawing diagrams of the wonderful re- ceiving set I was going to build. Finally I worked out the plans for a receiver that I was positive would be a world-beater. an “aluminum” variable condenser that rust- ed, a variometer that melted in the sun, and a tube socket that broke when I tapped it” know, for that wonderful first set of mine was made of them—all but the panel, which really was made of the ma- terial advertised on the sign. I WAS an easy mark for those “‘gyps,” and the way they handed me absolute junk in exchange for my hard-earned dollars was a crime. The plates of the variable condenser were supposed to be aluminum, but a spell of damp weather left them with a beautiful coat of rust, and subsequently I found that a horseshoe magnet stuck to them like a long-lost brother. There was a variometer in the original hook-up, I remember, and it looked pretty good when I bought it; but I left it standing in the hot sun for several hours one day and the whole business actually — softened and sagged out of shape so I could no longer turn the rotor. The tube socket, too, was an excellent example of ““gyp” manufacture. I think it was made of the same ma- terial they use for stere, where I mentioned humbly that I was interested in buying a radio set. “Do you want one of the cat- whisker type or would you prefer an audion detector?” the clerk inquired condescendingly. That dazed me for a moment, and then I recovered sufficiently to ask the price of each type. It developed that the set which I understood em- ployed part of a cat would cost in the neighborhood of $25, while the set using the other device would run to all of $75, including the storage bat- tery and the various accessories, which the clerk assured me were quite necessary. I PAID $25 for the cat’s whisker and what went with it, and spent the whole evening installing the out- fit according to the alleged simple direction sheet. Yes, it worked—lI lived less than a mile from old WJZ, which was then located in Newark, N. J.; but some- The Proof of Reliability JN OUR December issue appeared the Con- fessions of a Radio Gyp, who told the in- side story of how the cheaters among radio merchants “bootleg” tubes, fake condensers, coils, and other apparatus. Here is the other side of the same story — the confessions of a fan who was duped by the radio gyps and who paid dearly for his experi- ence. What he says should prove helpful in pointing out the pitfalls and swindles in the path of the man who is just starting in radio. By stamping its seal of approval on the prod- ucts of reliable radio manufacturers, the Popular Science Institute of Standards is helping to force the gyps out of the radio field; so that the day is not far distant when the novice, as well as the expert, will be able to buy sets and parts with the assurance that they are reliable. In the meantime, the be- ginner will do well to stick to manufacturers and dealers who have established reputations for honest merchandise and fair play to the buyer. ‘molding the clay disks that trap- shooters aim at with shotguns. Cer- tainly it was brittle enough—my screwdriver slipped while I was assembling the set and struck the side of the socket a very gentle blow, whereupon a large piece dropped out. Really, it was a tribute to the broadcasting stations in operation at the time that the set brought in any- thing at all. I COULD go on and tell, part by part, just how each instrument finally revealed itself as a fraud and had to be replaced with the genuine article. Eventually, the whole re- ceiver was rebuilt. The matter of “gyp’” parts no longer bothers me, for I have learned to know genuine parts when I see them and I am familiar with the trademarks of most of the reliable manufacturers. Still, it was a -plea- sure the other day to note, as I walked by the store where I bought my first set of parts, that the “‘gyp”’ how the tuning lever did not seem to be of much use. If WJZ was broadcast- ing, I could always get the station most anywhere on the dial, and if it wasn’t, no amount of tuning would bring in any other station. For several months the crystal outfit kept me satisfied. Then I began to long to hear distant stations. That meant a tube set, so I read all the radio literature I By this time a change had taken place in the radio market. The tremendous demand, coupled with the inability of the legitimate manufacturers to fill the orders, brought a lot of fly-by-nights into the game with plausible-looking substitutes for almost any of the standard radio parts. That these “gyp” parts were almost useless goes without saying. I who ran the place finally had gone to the wall and that an auction sale was being held under the unfeeling direction of the sheriff. For the sake of all those who are just starting in the radio game now, it is a pity that many of the ‘‘gyp”’ fraternity are still in business. Doubtless there are still thousands of beginners who will have to learn by experience as I did. Febr' fy

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ft ne al 1d SS ad of n0 he be an of re. de a= or p- T= ny as he Ww, by nt nd ine re- .ed. see the ble ea- xht 'p to vas ion ust sa ‘ity are ave ‘wires in the re- February, 1925 POPULAR SCIENCE MONTHLY 89 The Month’s Curiosities in Radio A Multiple Hook-Up—Unusual Sets and Accessories LS er ——— Fuse Protects the Tubes It is connected in the minus B bat- tery line and will burn out instantly when the current rises to between 140 and 200 mil- liamperes, so that if the high-voltage ceiver become crossed with the filament circuits, or the B battery is ac- cidentally con- nected in place of the A battery, the fuse will burn out and the tube fila- ments will not be injured at all This Fan Tries Them All According to Peter Testan, Jr., of Brooklyn, N. Y., the only way to find out which type of receiving set gives best results is to test them all under exactly the same conditions. In his laboratory shown below, he has an elaborate collec- tion of radio receivers, including nearly all of the popular types. A switching arrangement permits him to shift in- stantly from one set to another so that he is in a position to judge value in the reception of distant and local stations Radio Set in Vanity Case Another of the novelty receivers at the Chicago Radio Show was built into a vanity case after the powder puffs, powder compartments, and the other usual fittings were removed. It is a crystal receiver. The tuning inductance is shown at the bottom and the four binding posts at the top are used to con- nect the set with the antenna, the ground, and the head phones. The pic- ture shows it removed from the case The Radio Peddler Appears In many foreign cities, the peddler’s pushcart loaded with an assortment of the cheaper radio parts is a novelty Old Shoe Houses Radio Here is a_ perfect receiving set, built in an old shoe by Elaine Rabinoff, which carried off a prize in the novelty class at the recent radio show in Chi- cago. It is a crys- tal receiver, and on test showed effi- ciency about equal to similar small crystal sets built in a more conven- tional form. Notice the tuning dial at the side of the shoe near the heel, and the binding posts for buttors Loudspeaker like Throat A loudspeaker that is designed after the human throat and its adjacent passages has just appeared on the market. In addition to the main channel for the sound, there are other passages in the molded composition that the inventor claims add much to the naturalness of reproduction. An artist and a sculptor assisted in working out the final design of the instrument so that an attractive and ornamental loudspeaker is the result nee

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Tap tegen eras Se re SS LY ea CEES, ie Fea Taste: Aaah arian Ne eee i ctaid mane nopemmesmira aes LES a eee Sevag te iepeaeeillne te nite Sarde Ginarear OF Saeaniae xése. acacia 90 POPULAR SCIENCE MONTHLY February, 1935 SK IDDING—How to Avoid It An automobile expert tells of simple ways to save your car from disaster on treacherous roads By George Arthur Luers LIGHT car and a heavy foot make a combination that works well as long as you traverse dry and un- obstructed concrete roads. But when the roads are glazed with ice, when they are wet from snow or rain, when they are freshly oiled, when a light rain has converted the fine dust on old roads into slippery mud, when you at- CENTER OF CAR. WEIGHT

roads, for that matter. Then the neces- sity for making sudden stops—one of the most frequent causes of skidding—will be removed. Also, the skilful driver will control his car speed mainly with the engine, closing the throttle or even shift- ing into a lower gear and using the throttle to slow down under adverse road conditions. If this does not control the car, it is permissible to apply the brake, without releasing the clutch, which keeps the wheels rolling in a definite direction. Avoid driving directly UNEQUAL DISTRIBUTION OF CAR WEIGHT CONTRIBUTES TO SIDE SLIPPING.

a CENTER OF CAR WEIGHT tempt to avoid a stretch of bad going by driving on wet trolley tracks — then this combination is likely to prove danger- ous; for it leads to skid- THE HEAVIER THE REAR OF THE CAR, THE GREATER THE TENDENCY TO SWING, REQUIRING _ CAUTIOUS STEERING AND REDUCTION,

ding. OF SPEED In fact, the heavy foot that always presses the accelerator down to the limit and suddenly jams on the brake every time it is necessary to stop, is a dangerous thing to have in any car on any kind of highway. Unless you are an exceptionally skilful and experienced driver, your first ten- dency, when you feel the rear of your car slipping sideways into a skid, is to push down hard on both’ brake and clutch pedals. You want to stop the car as quickly as possible. SKIDDING ear, however, can’t be stopped with its. brakes. When you throw out the clutch and apply the brake, you lock the rear wheels. The wheels eannot rotate, the grip of the tires on the slippery roadway is slight, and the con- sequent difference in traction between the locked rear wheels and the revolving front wheels, coupled probably with an unequal distribution of weight in your car, causes a skid. One fact must be appreciated by every owner—that no car has ever skidded with- out cause and the driver is*almost in- variably the contributor of the cause. Underlying many instances of serious skidding is the nervousness of the driver. The terror of the sudden side swing robs the driver of his ready reasoning power, and a movement of the foot or hands brings on the skid with uncontrollable suddenness. The thing to do is to drive slowly always on slippery roads—on any sort of to a curve at high speed or abruptly around another vehicle. Instead, learn to reduce your speed with the throttle a considerable distance in advance of the turn, and then make as wide a turn as possible. A good rule to remember is to make the movement of your steering wheel always proportionate to the speed of your car. You can turn the wheel

halfway round in perfect safety when yoy are going slowly, whereas at high speed a sixteenth of a revolution of the wheel ma invite disaster. The wheel should be held steadily and any suddenness in change of direction avoided. It is not necessary to coast around a turn; in fact, it is better to keep the clutch engaged, closing the throttle to retard the forward movement of the car. "THESE precautions should be sufficient to prevent your skidding in the or. dinary conditions of driving. Should the car skid, though, despite all your efforts to be careful, you can right it, or help to right it, by turning the steering wheel in the same direction as that in which the rear end is slipping. It is evident, of course, that this procedure may neces- sitate steering toward a ditch, when the rear swings in that direction; however, this is a consideration that makes it more necessary to take the curve cautiously at a safe speed. Skidding at curves applies to both wet and dry road conditions. A _ straight road, of the crowned, or raised center variety, also can contribute to skidding even in dry weather. Ordinarily in driving along such a road you will straddle the crown instinctively in order to keep the car level. Sometimes, though, it will be necessary for you to turn out to permit another car to pass. Then look out for skidding! Slow down always when you leave the crown, for obviously the slant- ing car tends to slide over toward the ditch. So slow down, go into low gear until you are back astraddle of the crown again. If necessary, stop, and

ii cB fa

THE DIFFICULTY OF TAKING T AT HIGH SPEED.

HE TURN —_——— << i wt ee em ee ocr Mit,

i. “2 wil 4

Why a sharp turn of front wheels at high speed will often cause an automobile to skid

Febt ther of t the grea sug T car cars accd thar esp! ster: the youl roa¢ evid fart and ever the mo! the stee mos over whe ing thou the tion. ily weig of th no ¢ by to ti the s rear wart not s The! do, ¢ inva whe forw the. poss! cond ment tires weig on t] com) Sore = il

Page 59

>» 1925 it n you eed g ] May e held nge of ary to better ig the ement ficient he or- Id the efforts elp to neel in ch the nt, of neces- en the wever, t more curve eed. applies y road traight ned, or ariety, ute to n dry rily in uch a craddle ctively the car vill be permit out for en you > slant- ird the Ww gear of the p, and February, 1925 then make your way back to the center of the road as cautiously as you can. If the road is of clay, and wet, take even greater precautions than those I have suggested. ; Too much weight in the rear of the car contributes much to skidding. Closed cars likewise are more likely to skid, on account of the distribution of the weight, than open models, especially road- sters. If you study the movement of your car along the road, it will be evident that the farther forward and the more evenly distributed the load is, the more responsive the car will be to steering. When the most weight is over the rear wheels, the steer- ing wheels, even though inclined in the desired direc- tion, cannot read- ily control the weight to the rear of them. With the rear wheels locked and no defined direction of travel maintained by them, the heavy rear weight tends to take control over the front of the car. OF BRAKE IS DANGEROUS, bps condition will be evident, espe- cially when a car is proceeding on the side incline of a wet road. The locked rear wheels are restrained against for- ward movement, and obviously they can- not slide up toward the crown of the road. There remains but one thing for them to do, and that is to slide down, which they invariably do. The steering or front wheels are not locked and are free to roll forward. The result is that the rear of the car swings around to the front and possibly ditches the car. It is desirable practice under every condition to carry passengers and equip- ment well forward in the car. Even spare tires and tools add a desirable forward weight, and the mounting of spare tires on the front fenders or the use of trunks, compartments and storage boxes forward POSITION ON CROWNED ROAD WHERE USE 4 CROWNED ROAD POPULAR SCIENCE MONTHLY on the runningboards, is more desirable than having their weight at the rear. Chains, of course, will lessen the like- lihood of skidding. These are applied ordinarily only to the rear wheels, but there are extremely wet conditions under which the front wheels will not hold direction, when it is essential to carry chains on all four wheels. Balloon tires are credited with having less tendency to skid than others. This is probably true, for tires that are not too heavily inflated or tires that are soft, seem to have better tractive qualities. It is possible the greater area of rubber in contact with the road grips the pebbles and projections, thus holding the car fairly steadily, while the high-pressure tire cuts and slips past all projections. One noticeable advantage of the soft tire is that it resists being turned readily from its path or direction of rolling, thus tending to prevent a skid. In wet-road driving, the foremost pre- caution is to avoid that sudden change in direction. Fairly good speed can be maintained on the straightaway, but to make an abrupt turn is always dangerous. Under-inflated or balloon tires, both of which resist or restrain the car in abrupt turning, undoubtedly are safeguards. —— “BEGINNING OFASKID WITH BRAKES LOCKED, WHEELS SLIDE WITH EQUAL FACILITY 10 THE SIDE FRONT WHEELS TURNED IN DIRECTION OF SWING OF Skidding of the rear wheels can be overcome by turning the front wheels in direction of skid OVER THE CROWN THE HEAVY REAR The driver who OF CAR SEEKS THE DITCH 91 With them the road contact also is better, for the softer tires will not bounce off the road, leaving the rear end free to begin swinging. Speed on turns is the force behind the skid, and the lower the speed the lower will be the force that inclines to skidding. Any abrupt change in direction, regard- less of tire equipment or chains, must be at a slow speed, that the forces stored in the car will be controllable and so re- duced that the tires can maintain traction. bd YOU are inclined toward nervousness and are inexperienced in driving on wet roads, apply chains to all wheels, keep on the crown of the road, and under no circumstances swing the front wheels rapidly, unless the car is moving at a speed below five miles an hour. faces the greatest danger of skidding is the one whose car never has skidded and. who therefore remains blissfully ig- norant of itshazards. He has experienced as none of the feeling of : absolute helplessness that comes ‘over the man at the wheel when the ¢ar slips out of his control. I remember that when I first drove a car all roads were alike to me. Whether they were wet, dry, oily, or dusty, it made no difference—I sailed along just the same under all conditions on the straightaway, and took the turns figur- atively on one wheel. Then one day, when the road was slippery after a slight rain and I was driving along a straightaway at about 35 miles an hour, a coal truck suddenly poked its great nose out of a side street and started to cross directly in front of me. I turned the wheel sharply, at the same instant releasing the clutch and stepping hard on the brake— I SHALL always remember vividly the sickening sensation as the wheels of my car refused to obey my hand. We spun around, my car and I, missing the truck on one side, and a telegraph pole on the other—by inches. In less time than it takes to tell it, I had learned my skidding lesson. From that day I have taken no chances, for -I know the possibilities of disaster that lie in slipping wheels. And so, if you are one whose car never has skidded, take my tip and follow the simple precautions I have mentioned. They may save you from one of the costly accidents that bring tragedy to thousands of motorists each year. $50 in Prizes HAvE you a workbench in your home, and do you like to build useful things? If so, turn to page 130 of the Home Workshop Department. There you will find the announcement of a prize contest that is sure to interest you.

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92 POPULAR SCIENCE MONTHLY February, 1925 Saving Auto-Repair Costs What the Car-Owner INDING it next to impossible to clamp Fk a ball-socket cap in a vise for filing, I made a convenient holder out of two old caps The.old caps are gripped in the vise and the one to be filed is, If no vise is at hand, the cap and holder can be rubbed over a file lying flat on and two bolts, as shown in Fig. 1. laid over them. the bench.—LAWRENCE TORELL. O REMOVE or replace a crankcase is a difficult and annoying job for one man. Jacking or blocking up the case helps, but is somewhat awkward and may cause dents in the bottom of the case. A better method is to use a few old springs and two or three lengths of hay-baling wire, or wire of equal strength (Fig. 2). On one job I saved an hour by this means. If no mud-pan clips are pro- vided, stiff pieces of heavy wire may be bent to the proper shape for attaching the supports and hooked or fas- tened to the springs or frame. The supports should be of a length to suit the car; the ones I used were 18 in. long. — RICHARD C. TARR. ANVERTED CAPS Fig. 1. Filing a ball-socket cap WNERS of corrugated sheet-metal ga- rages often find that the cold pen- etrates them to such an extent that it is difficult to start the auto- mobile on winter mornings. In the summer, too, these garages are apt to become very hot, to the detriment of the ear’s finish, as well as the tires, uphol- stering, and top. One construction company, which care- fully studied these objections to the other- wise economical, durable, and serviceable metal garage, has developed several types of inside sheathing. Any handy man, however, can line his garage with easily and cheaply obtainable wallboard. It comes in large sheets and is nailed directly to the studding, as shown in Fig. 3. The corners are finished with quarter-round molding and a baseboard is nailed around the bottom. The cost often can be kept within $15.—GEORGE A. LUERS. th YH); Y RADIATOR HOSE Fig. 4. erage a garage is wired for electric- ity, it is a simple matter to wrap a heating pad around the lower hose con- nection, running from the water jacket of the engine to the bottom of the radiator, Te. :¥, cells or may be supported with wires and mn Avg ELECTRIC HEATING-PAD Heating pad pre- vents radiator from freezing OLD BED SPRING CRANKCASE Fig. 2. While replacing the bolts, a crankcase springs Can Do for Himself ie COLD weather a good strong spark is necey sary. trated in Fig. 5is valuable. Use it either with dry To insure having one, the tester illys. storage battery while adjusting the yi brator togive a high-pitched buzz and regy. late the spark-plug gaps until the strongest pos. sible spark is given. _ help in winter and summer.—CLYDE E. Vouxgrg, I find this apparatus of Fo? giving hand signals at night, the devices illustrated in Fig. 6 are ex. cellent. One is a white disk painted on the left gauntlet; another is a polished disk of white metal, and the third is q small ruby lens, all of which reflect the light from any following car.—A. G. . | ‘HE annoying GALVANIZED IRON “cracking” and “snapping” of the spokes in wooden car wheels often can be prevented by turning a light spray from the hose on them at intervals to swell the wood. If the trouble is due to drying out of the wood, and not to short spokes or other cause, a permanent cure is made by soak- ing the wheel in BASEBOARD | i, 3/4" 6" Fig. 3. How metal . garage is lined WIRES TO 2OR3 LEFT GAUNTLET Fig. 6. Hand sig- JEWEL-CUT nals for RUBY mo v5 night auto driving PAINTED WHITE POLISHED 2'4"DIA. — WHITE METAL as in Fig. 4. Two leather straps hold the pad in place and it may be covered with sheet asbestos, if desired. The cord is shortened so that one half of the plug is only a few inches from the pad. The other half of the plug is con- nected by means of a long cord with a lamp socket. When you drive in on cold nights, plug in the three-way switch on high, low or medium, according to the weather, and your car can be left in safety, as the pad is provided with an automatic thermostat, which prevents overheating.—F. S. Root. Fig. 5. for auto coil and spark plugs wey, DRY CELLS linseed oil, and 2 then painting. HILE on the road, the key driving the fan on my light car loosened up enough to allow the fan to slip forward and damage the radi- ator by constant rubbing. As no one was dressed for a greasy re- pair job, and the fan belt had to be left on to drive the pump, further damage to the radiator was prevented by twisting the fan blades to the opposite angle so that the “propeller” action tended to keep the fan against the rear bearing rather than to draw it forward into the radiator.— HAROLD E. BENSON. Simple testing board A RUSTY rim is apt to cause slow leaks in an inner tube unless a “liner” is used. I find a good substitute for a regulation liner is a layer of friction tape wound on the rim. The turns of tape should be overlapped about 4 in. so as to form a continuous band around the rim, except where a hole is cut through the tape for the tire valve. Two rolls of electrician’s tape are sufficient for four rims and, of course, costs consider- ably less than ordinary liners.—DONALD H. PALMETER. scre ness smo bur: grat he « Esk: is di ture “Sh sno As a IS O} if n buil quic the mat ple desc arti

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neces. r illus. th dry he vi- regu- st pos- tus of LKERS, ht, the aTe ex. ted on olished rd is a ect the G. inoying .cking” \pping” okes in Nn car ten can ited by a light ym the them at to swell . ifthe ; due to it of the nd not spokes cause, a 1t cure y soak- vheel in vil, and nting. LE on e road, driving on my oosened ugh to > fan to ard and the radi- constant As no dressed easy re- e left on ze to the ting the so that keep the her than liator.— use slow unless @ ubstitute f friction turns of it 4 in. 1 around 2 is cut ve. Two icient for consider- -DONALD POPULAR SCIENCE MONTHLY How You Can Build a Snow Igloo Imitating the Eskimo in Novel Sport for Snowdrift Days ITH his right arm afire like a torch, an Eskimo boy burst screaming from a snow igloo. Lieut.- Comm. Green, U.S.N., busy withdog har- ness near by, seized the pain-crazed lad, smothered the flames, and doctored the burns so skilfully that they healed. In gratitude, the boy’s father asked how he could repay so great a debt, for an Eskimo with a crippled hand By Fitzhugh Green Cut a rectangle about 2 by 3 ft., slant- ing a bit toward the bottom. On the edge toward you, gouge out a trough 1 ft. wide and from 6 to 10 in. deep. This trough enables you to slide the knife blade back 132, place the last two blocks up-ended at the front right-hand corner. This gives you a starting slope for your spiral when you cut away a triangle as indicated by the dotted line. Start the succeeding row with a full block lengthwise. As you near the back wall, begin to slope the blocks slightly inward. It is very important that is doomed to the endless tor- ture of unescapable frostbite. “Show me how to build a snow igloo,’’ was the reply. As a result Commander Green is one of the few white men, if not the only one, who can build an igloo as well and quickly as the most expert of the Eskimos. It is merely a matter of knowing a few sim- ple tricks and these he has described in the following article. edges be well fitted. An Eskimo does this by shaping his block as neatly as possible before lifting it into place. He then lays it gently on the underneath wall and slides it slowly against the preced- ing block. Holding it with his left hand he works his knife back and forth be- tween its edges and those adjoining. Gradually it sinks into place. The soft snow Careful fitting of the keystone block in- sures a self-supporting, blizzard-proof roof SNOW igloo in some ways is the . most remarkable dwelling con- structed by man. An igloo for 10 people can be built in 45 minutes. No tool is required except a long knife; no material save snow. Once finished, it will support three men on its roof. A cyclone could not demolish it. It is air- and water-tight, sound- and tempest-proof. It is warm, dry, light, durable, well ventilated, and clean. Its door has weather strips, but no hinges. Its window is transparent, but unbreak- able. Its floor is marble-white and hard, yet can be replaced in 10 minutes. Properly initiated into the mystery, any man can build an igloo the first time. It is important to select proper snow. Find a drift packed hard by the wind. Test it by pushing your butcher knife into it. If the snow yields grudgingly, it will make good blocks. Photos courtesy American Museum of Natural History Building the walls with blocks of snow joined closely and later welded by heat and forth under the block your vertical cuts have outlined. Dislodge the block by a gentle kick or two in the horizontal crack. The other 50 blocks are easily cut, working from this space. With your heel mark an ellipse 8 by 10 ft. on a smooth packed surface, sloping slightly, if possible, in the direction you wish your igloo to face. Lay a ring of blocks lengthwise, edge to edge, on this outline. As shown in the sketch on page What the Mechanical Departments Offer You AGES 93 to 133—The Home Workshop, with 34 articles tell- ing how to make furniture, toys, household conveniences, and novel- ties—a handbook for amateur me- chanics—illustrated with 38 drawings and 26 photographs. Pages 134 and 135—Shipshape Home Department. Pages 98 and 136 to 146—The Better Shop Methods Department packed with time- and money-saving suggestions for the professional me- chanic—17 illustrations. Special Handicraft Contest An- nouncement on page 130. vestibule for sheltering dogs and footgear powder loosened by his knife becomes, in effect, a mortar. Finally, with a thump of his knife hand, he drives the block firmly and tightly into its resting place. Success with an igloo centers in the arch. And success is easy if one remem- bers the principle involved—that any domed structure is self-sustaining when its parts permit distribution of stress throughout the whole. No snow block must be laid at an angle that puts its face out of line with the curving spherical surface of which it is an element when the igloo is complete. A few trials will show that as the spiral rises the walls may be sloped more and more sharply inward. Block faces in all cases above the first tier or two are beveled as the cover edges of a hallowe’en pumpkin or a pineapple cheese are beveled. This (Continued on page 132)

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Beautiful Sal

woodwork and wish to astonish your family and friends by building a piece of furniture that will appear to be the work of an experienced craftsman, you cannot find a better project than the attractive Salem chest of drawers illus- trated at the right. Incidentally, few pieces of furniture are more appreciated. In almost every home there is room for another chest of drawers, and just now the low type, developed so beautifully by Colonial cabinetmakers, is becoming exceedingly popular. From the standpoint I’ YOU are a relative beginner in POPULAR SCIENCE MONTHLY February, 1925 em Chest Easily Made Has no Difficult Joints to Puzzle the Beginner in Woodwork A Salem chest of drawers to grace any bedroom

progresses, will be child’s play in compari- son to the work usually entailed in mak. ing a piece of furniture. The exact size of each piece necessary in building this chest is given in the foj- lowing bill of materials. Each item jg lettered to correspond with the accom- panying drawings. The dimensions are given in inches. The woodwork can be made of mahogany, gumwood, or any cabinet hard wood you prefer to use, ex- cept where otherwise noted. A_ Top of case, 4% by 22 by 42, either solid hard wood or plywood, 1 required. (Continued on page 123)

of construction, this piece

is entirely unique. It is

safe to say that never was ‘ TT designed a chest of draw- G ers so distinguished, for |

beauty and refinement of proportions and at the Na ae same time so simplified

that it does not require the making of a single 9} odie uP difficult cabinetmaker’s

joint. There is not a mortised and tenoned, a dovetailed,

9 NJ cf >

eee ----| * 2

> > >» Oo eo) IEE] - es

% N *

a tongued-and-grooved, or

even a rabbeted joint in

the whole piece. Most of the parts are put together with butt joints, such as are used in common boxes. A few of the joints are plain miters, which can be cut in a miter-box with hardly any chance of error. Even the drawers, which the amateur usually dislikes to make because of the careful fitting that is required, do not call for any especial skill or knowledge of cabinet- making and joinery. The main essential in constructing this chest of drawers is to study the drawings and bill of ma- terials given later on until you have obtained a clear idea of the relation of the parts. Then buy a suffi- cient number of boards to make the chest. What you get will depend some- what upon what your lumber dealer has in stock, but he will be glad to help you select stock that will cut to best advantage. Then cut all the main pieces to the correct di- mensions as accurately as possible. You will find that it is a simple matter to assemble the pieces. It is just like building a house of blocks, because the parts go together naturally. What little fitting becomes necessary as the work

SIMPLIFIED SALEM

CHEST of DRAWERS

REGULAR DRAWER P CONSTRUCTION MAY BE USED IF PREFERRED

Fet o T a T ir <a O eae ~@6o pS Bae o Ra Ss a Sa

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» 1925 le ipari- mak- SSary e fol- em is ecom- IS are an be ' any e, ex. id hard February, 1925 POPULAR SCIENCE MONTHLY 95 This Beautiful 25¢c Book on Wood Finishing Our book gives complete instructions for finishing all wood— hard or soft—old or new. Tells how inexpensive soft woods may be finished so they are as beautiful and artistic as hard wood. Explains just what materials to use and how to apply them. This book is the work of experts—illustrated in color—gives covering capacities— includes color charts, etc. Use coupon below for a FREE copy. JOHNSON’S WOOD DYE (Penetrating) Johnson’s Wood Dye is very easy to apply. It dries in four hours and will not rub off or smudge—penetrates deeply, bringing out the beauty of the grain. Johnson’s Wood Dye is made in 17 popular shades as follows: No. 128 Light Mahogany No. 125 Mission Oak No. 129 Dark Mahogany No. 130 Weathered Oak No. 127 BrownMahogany No, 110 Bog Oak No. 329 Red Mahogany . No. 120 Fumed Oak No, 172 Flemish Oak No. 123 Dark Oak No. 178 Brown Flemish No. 126 Light Oak No. 131 Walnut _ No. 124 Golden Oak No. 140 Early English No. 160 Brown Oak No. 180 Gray All shades may be easily lightened, darkened or inter- mixed. Full directions on every label. Select the shade of Dye you want from the list above and order it from your dealer by name and number. $C. JOHNSON & SON, Racine, Wis., U. S. A. ‘¢The Wood Finishing Authorities” © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. Johnson’s Wood Dye is a dye in every sense of. the word. It contains no finish whatsoever. Like most first class products it answers one purpose only —it dyes the wood —the finish must be applied over it. We recommend Johnson’s Varnishes or Johnson’s Polishing Wax. Ask for a - FREE copy of the Johnson Book at the Best Paint or Hardware Store in your locality. Stores displaying the Johnson Service Department Sign shown below can furnish the Book and full information on how to finish wood the proper way. Or, use coupon below. = aap ame qeaaleaealembenape tina ge a cegralped enagpeigbenttenets lin S.C. JOHNSON & SON, Dept. P.S. 2, RACINE, WIS. i ““The Wood Finishing Authorities’’ 4 a SERVICE | \ is t DEPARTMENT (Canadian Factory—Brantford) x i J Please send me free your 25c Instruction Book on Home Beautifying and Wood Finishing. I enclose 3 z 10c to cover postage and wrapping. i i f ee DARI FS 36 5 os Boi. 4 cee dose RRR eee ; - OW IGT 5 os. cis 000 60 MeN be ees Cree nore ee unenE q 4 PUIG 566 icc ciacdesDescvativesegeetetea” i ‘ 4 City and Gtthe xc).. 260s oie bcs uh eae tee JER y ye ge ee eee a a gS

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96 POPULAR SCIENCE MONTHLY February, 1925 Making Removable Seat Cushions Easy Ways to Do Your Own House and Auto Upholstering A always _ encountered. workers, draftsmen, motormen, and many others sit on hard stools that would be much less fatiguing if pro- vided with cushions. It is not always possible, however, to get a cushion that will fit the chair or stool you use. In that case you can make one yourself. First determine the size, the kind of material you want for a cover, and the kind of stuffing with which to fill it. Figure 1 shows how a pattern is laid out for a cushion 114 in. thick and 12 in. square. From this plan you can modify the dimensions to suit your own requirements. For a cushion that is to have hard and continuous service, a cover of COMFORTABLE seat with a good cushion is a combination not Office By William T. Weld Shopwork Instructor, Central High School, Peoria, III. No one knows better than Mr. Weld the tricks of doing simple upholstery and chair seating. His next articles will tell how to recane chairs and repair upholstery of various kinds stuffing, AFTER you have your material ° cut to these over-all dimen- sions, start from the left edge, B, ’ Fig. 1, and measure over as indi- cated until the right edge, B, is reached. A pin may be inserted for reference on each line as it is Make all your measurements accurately and be sure that all corners are laid off square. The same procedure is done from edges C to A. Then cut with a pair of scissors or a sharp knife on all the lines indicated by the heavy lines of the drawing. measured off. Two methods of making the seams heavy material, such as canvas or artificial leather, should be used, while for porch swings, lawn seats, cedar chests, and the like, a good grade of cretonne will serve. Curled hair, while the best material for is rather expensive, cotton or Spanish moss can be used. Moss makes a light cushion, is inexpensive and does not pack down readily from continued use. so kapok, Tying on a button with a tufting knot (above) You | are now ready for the stitch- ing. ~ The use of a sewing machine makes a neater job, but with a little care and patience a good cushion may be made by hand. Figure 5 shows how a section of this type of cushion will look. As shown at D in Fig. 1 and in Fig. 5, the lower loops or seams are sewed permanently, after being folded properly, CHAIR CUSHION To determine the total length of the and (below) sewing up the stuffing opening material needed, add twice = 1 “ desired length and twice the de- PATTERN FOR BOX CUSHION Sas SS See sired thickness to the sum of the —eE “eo aaa figures representing the amount of ‘fF ‘ HK mf =, material needed for folding in the l| if LE seams, usually 234 in. To deter- f Tet mine the total width of the ma- _,|\|—lENGTH aes wee: |i LENGTH terial needed, add twice the de- — | Sew. F|| E | sired thickness plus the width to 10 t v ! UNEP TADNe Sali the sum of the figures representing | |FOLD HERE $ | a S da : the folded material, which in this fj i's \ |. i direction will be 214 in. ( a ee ae Wars THICKNESS TING LINE ac oe ae eI mare AUTO DRIVER'S WEDGE CUSHION while the seams at A, B, and C are fipgt - basted or pinned temporarily in the proper position. The purpose of this folding is to conceal the raw edges of the material and to make a finished edge that will wear well. The loop formed also serves to hold welting cord in place if yoy desire to use it (Fig. 6). The seams marked D are first sewed then the vertical sides are folded up and the flaps E turned in together, and the corners are stitched from the inside. Next, fold the upper surface (C, B, A) into place, which will take a position so that one F will be directly over the other F, thus really forming a cloth lid to the box cushion you are making. Proceed to stitch this into place, as shown in Fig. 5, and continue around three sides and about two-thirds of the way along the fourth side. The stuffing then is put through this opening, after which it is sewed up. This method of making a box cushion has the advantage of keeping your material all in one piece and that all of the stitching, with the ex- ception of the vertical corners, is done from the outside. Figure 8 shows a method used by upholsterers. In this the welting cord is covered first by a narrow strip basted in place, and then stitched between one vertical edge and one surface. These are held together as shown and stitched from the wrong side of your ma- terial. This is done at all seams, an opening being left for the purpose of putting in stuffing; then the whole cushion is turned right side out. An edge seam of this type appears as shown in Fig. 9. IGURE 10 shows a_ simpler method, with the cord omitted. The top and bottom pieces are cut MOTORCYCLE REAR SEAT IN USE THIS ALSO LS _ TURNED WITH THE THICK END UP Pattern for a straight side or box cushion, a removable chair cushion, and motorcycle and auto ‘cushions Stepsin tying an upholsterer’s tufting knot | ad to proper size, the vertical edge is cut in one long strip of the proper width and length and sewed to- ‘ gether at the end. The edgés of adjacent and corresponding sur- faces are then placed as shown in Fig. 10 and stitched about -14-in. from the raw edge. This is done all the way around on both the top and bottom surfaces. The cover then is turned right side out, as ex- plained before. Figure 11 shows how this seam looks when finished and turned. The stuffing is pushed through the opening left at one edge. Take a small amount each time a and work it well into all == the corners with a long Fc narrow stick or by put- ting your arm through the opening and using your fingers. Fill the cushion until the center is about twice as thick as you really want it. You are then ready to tie (Continued on page 122) FIG.I Details of seams and tufting FIG.IO

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Ys 1925 Sebéwery, 1995 POPULAR SCIENCE MONTHLY 97

& 1S H sZt r : Pr x — Heer o — S.

takea ti y i ' Grill rom the front sie ofthe lirectly . Size 7 x 12 rit naar Meng wie f MANUFACTURED BY fol lice ge a re etiddend tend os taps. * ; | : DIAMOND STATE FIBRE COMPANY Maw ee lace, as - BRIDGEPORT (Near Philadelphia) PENNSYLVANIA, U. S. A. haloes ‘= core around mm MAKERS OF eo a oneas Gaarene a q the rubbing a lone in one irds of : CrLoroN - Diatnond-Fibre -VutcawooD ee e. The vrs f wa As popular as radio itsel narrow . d then al < S more and more radio novices become ire né ° stitched , seasoned fans, the popularity of Celoron Jur mMa- 4 ‘ pel Panels multiplies. hg Today Celoron is the accepted standard for pei radio panels. Sets of many foremost makes are equipped with Celoron panels and parts. simpler Celoron does not chip or crack. It does itt : e - e pi ' not soften, warp or buckle. Itisinfusible and Coitiiiliaiecdiaalaaieaia — : will stand up under atmospheric changes. ite lame: im — in standar en s wed to- * d di ters—all sages ot Look for Celoron Panels where you buy scowsmaieanaaaaae ng sur- your radio supplies. Insist on Celoron in- m ° ° t ida sulation in the parts you buy. nites done all *: . “ CrioroN the top Celoron is also made into tubing that has Foon cel all the insulating qualities of sheet Celoron. CusoroN 1 It is used extensively by manufacturers of finis the best radio instruments. It is made in all sizes. This rack on a mer- DIAMOND STATE FIBRE COMPANY rocane that he wants tc give you the best in

Bridgeport, Pa., and Chicago, IIl. radio parts. nei The oldest and largest manufacturer of vulcanized hard fibre of seams and laminated technical materials in the world. ris) ufting — Wherever you see a factory chimney, there are countless elec dy to td trical and mechanical uses for Celoron and Diamond Fibre.

© This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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POPULAR SCIENCE MONTHLY February, 1925 Secrets of Success in Grinding What Every Machinist Should Know HE art of fin- ishing metal surfaces by grinding is a branch of metal working with which you should be familiar if you are connected in any way with By H. L. Wheeler Machine-Shop Foreman lasting finish. A good grinding-machine operator acquires the ability to do first- class work only through several years’ experience with the various kinds of grinding machines, And in many cases about Abrasives knew just how to ‘“‘baby” it to turn out a good roll. As he was a man well along in years, several attempts had been made to break in new men, but they all gave it up in disgust. This was, of course, an exceptional case. As this is the day of specialists in the machine business, there are specialists in grinding—men who make it their machine - shop work. While grind- ing has been in use almost as long as theprac- tice of hardening of metals and tools, and probably was first used in connection with the reduction of metal that had been hardened, such as axes, tools, and machine parts requiring to be finished after harden- ing, the practice has grown enor- mously. Today machine parts of various metals, whether hard or soft, are finished by the grinding process. The finish produced by grinding is a superior one. The grinder is in a class by itself, when compared with the lathe, milling machine, shaper, H. L. Wheeler or planer. For rapid production of finished surfaces, the grinder cannot be excelled by any other machine. And so it is that the grinder is becoming a real factor in machine-shop practice. The amount of metal removed by grinding is, of course, small. The advan- tage lies in the fact that very little pres- sure is required to remove the metal. The liability of distorting the finished Fig. 1. steel crankshaft on a grinder ; Fig. 2. Feeding bushirigs into a new centerless gtinder. The work passes between two wheels piece is thus reduced to a minimum. This is well demonstrated in finishing a very long shaft by the grinding method and finishing a similar shaft by turning in a lathe. Careful inspection of the two shafts will reveal the fact that the ground shaft is straighter and more uniform in diameter, and has a brighter and more A heat-treated nickel the man must be “‘acquainted” with the machine. Grinding machines develop certain peculiarities that often result in spoiled work until the operator has learned all of the little weaknesses in- herent in the machine, if it be an old one, or the stiffness that is often noticeable in a new machine. I remember a job of grinding rolls for paper machines in a shop I was connected with a few years ago. The machine was designed for this particular job, but had been in service many years and was badly worn. There was just one man in the shop who could turn out satisfactory work on the machine. He had become so accustomed to the old grinder that he Fig. 3. Samples of the work done by the re- cently developed method of centerless grinding life work. And with constant prac- tice they get to know all about speeds and feeds, grind-wheels, and all the ins and outs of the grinding business. But almost every machin- ist is called upon occasionally to tackle grinding jobs. If his knowl- edge is well founded, he need not feel nervous about going ahead. Perhaps the most puzzling prob- lem is the selection’ of the proper wheel for the job in hand. Wheels are made in many grades, sizes, and shapes. The grade or grit is desig- nated by a letter or number, with reference to size of the grit of which the wheel is composed and the hardness or softness of the bond that holds the grit in place. The particles of grit repre- sent many thousands of cut- ting points. A grinding ma- chine that is equipped with the right wheel for the work in hand and working under normal condi- tions will remove a given amount of metal more rapidly thanany other process. The manufacturers of grinding wheels are experimenting constantly to improve Fig. 4. A modern hydraulic traverse grind- ing machine used for finishing long work their product and are discovering new and better ways to grind. Careful records are kept of each experiment and (Continued on page 140) ON’T fail to turn to pages 136-146, where you will find the continua- tion of the Better Shop Methods De- partment.

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February, 1925 POPULAR SCIENCE MONTHLY 99 out long nade ve it , an Why are Starrett Tools Standard in every Shop 1 the ts in their prac- bout _ and nding chin- ly to nowl- t feel attt f 21 Oy O EN CK SAWS 00 AY A prob- yroper /heels 3, and desig- mber, of the eel is rdness 1 that repre+ of cut- ig ma- 1 with > work condi- unt of oa Fine Precision Tools—2200 from One wheels nprove In something over forty years the From the first mechanics to whom Mr. Starrett Line has increased from a_ L- S. Starrett sold his Improved Squares single tool, the famous Combination = an eas cone ae 1 Square, to include over 2200 differ- country in the world which uses machinery ent Precision Tools, Hacksaws and ang precision tools knows Starrett as the Steel Tapes. Those years have seen standard of accuracy. the growth of a business that NOW Te- What is the cause of this world-wide pre- ris) quires the largest plant in the world ference for the Precision Tools that are devoted exclusively to the manu-} made in Athol, Massachusetts? If you use facture of fine mechanical tools. Starrett Tools you know. Shown in the group at the right are the following popular Starrett Tools: Micrometer Depth » Gage No. 440, Improved Firm-Joint Calipers, No. 26, Fay Spring Dividers, No. 77, Quick Reading Steel Tape, No. 510 (with Leather Case and Patented Push Button Handle Opener), Micrometer No. 224 A (with interchangeable Anvils giving range of 2" to 6"), Combination Square No. 11, and Thickness Gage No. 72. Write for Catalog No. 23 “Ww” — for description of the complete Starrett Line. ng new THE 7 S. STARRETT co. Careful W orld’s Greatest Toolmakers ent and Manufacturers of Hacksaws Unexcelled 136-146, ATHOL, MASS. ntinua- 7441 ods De- © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. ip ten 4 “ ‘

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100

POPULAR SCIENCE MONTHLY February, 1928

Tackle That Tough Job With a Trimo

1) <= { | H | In Steel Handle f | —Eight sizes from foe | 6" to 48" fie In Wood Handle H 5 a, 8, 10, 14 inch i ; sizes, i : If you need a Monkey Wrench, Chain Wrench or Pipe Cutter ask to see a TRIMO and judge for yourself as to quality and value. KC 7 fa \\ Endorsed by the Popular Science Institute of Standards Nothing is too stubborn for a TRIMO. Its sharp, deep-milled, drop-forged jaws bite hard and never lose their grip, yet do not lock or crush. Think of the time, trouble and bruised knuckles that this all-pur- pose wrench will save you. Rusted bolts, battered nuts, jammed threads—all yield to TRIMO. Nut guards to maintain adjust- ment, rounded threads in both movable jaw and nut and insert jaw in handle, readily replaceable when dull or worn, are important advantages that you won’t find in other wrenches. It pays to insist on TRIMO. Trimont Mfg. Co. Roxbury, Mass. TRIMo

MACHINE for spreading glue on the edges of boards, built as shown, will pay many times over for the slight cost and labor required in its con- struction. As compared with using a glue-brush, it saves a great deal of time. Furthermore, it prevents waste of glue and reduces the time necessary in cleaning off the glue ordinarily left on the face of the work, because of the unequal brush distribution. The glue reservoir is merely a large outer glue-pot, which is filled with hot glue from another container as often as necessary. This pot is set into the head of an empty nail keg, which is ballasted with junk iron or other weighty material. The glue is spread by means of a wooden turning which revolves freely. This may be plain or shaped to suit a tongue-and- grooved, rabbeted or any other style of

WS Novel Glue-Spreader Cheaply Built By A. E. Elling

common edge joint, The bail is removed from the glue-pot and the turning is fastened loosely with screws through the holes in the bailears. The turning should not be so large nor fit so tightly in the pot that the glue cannot drain back freely, For long pieces a helper is required to The glue is spread bya round wooden form which revolves in the top of an ordinary glue-pot {NK the work is pushed hold up one end as over the spreader. Any one accustomed only to the brush method of applying glue will be surprised at the neatness, quickness, and cleanli- ness of this inexpensive machine.

N RESPONSE to many requests from readers, POPULAR SCIENCE MONTHLY has in course of preparation a series of noteworthy articles on simplified model making.

How to Build a Dutch Crafts Hall Chair HE Dutch crafts chair illustrated is built on simple although unique lines. The necessary material, except the seat, may be cut from a clear, straight, well - seasoned oak or poplar board 12 in. wide, 34 in. thick and 6 ft. long. To pre- serve the lines, however, the seat, A, should be 11% in. thick. The heart - shaped openings cut in B, C, and D are 2 by 2% in. You will find

This sturdy little chair calls for only a few simple parts in its construction and is easily built it easy to draw one side of a heart, but to add the other side symmetrically is more difficult, so I sug- gest that you draw one side, cut it out, and use it as a tem- plet for drawing both sides of each of the orna- ments. After making the outlines, bore a small hole in each to start the blade of a coping saw or fretsaw. Brace E is 1 by 134 by 17% in. Tenons are cut (Continued on page 127)

rIS} This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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e glue is ead bya »und »oden m which olves in - top of ordinary jue-pot pushed » brush rprised cleanli- s from NTHLY series plified ir but to is more o I sug- t you > side, t, and a tem- rawing les of e orna- After ' the bore a ole in art the coping etsaw. Vis 1 by 714 in. ire cut xed on (27) —— February, 1925 EvEeREADY “B” Batteries today contain more electricity, more service, more satisfaction than ever before. Processes evolved by the scientists of the Union Carbide and Carbon Research Laboratories, Inc., when put in effect in the Eveready factories, are responsible for this great accomplishment. At the same time the factories have effected a still higher standard of workmanship. A system of inspection that is a marvel of efficiency was inaugurated. The results, gratifying beyond measure, were accomplished with a speed and completeness that have few parallels in industry. POPULAR SCIENCE MONTHLY 101 Scientists constantly improve battery quality aa coat \ WG Se es wae No.770. 45-volt extra large ver- tical, For heavy duty only. The ideal “B’? Bat- tery for use on multi-tube sets. Price $4.75, Sate = Dynan sen es Soe = The final tests showed more electricity, more bat- tery service, greater Eveready satisfaction with- out increasing battery sizes and with a substantial reduction in price. “B” Battery operating costs, using the new Evereadys, in most cases show a reduction of at least one-half. There is an Eveready Radio Battery for every radio use. Insist on Eveready “B” Batteries. Manufactured and guaranteed by NATIONAL CARBON COMPANY, Inc. Headquarters for Radio Battery Information New York San Francisco © Canadian National Carbon Co., Limited, Toronto, Ontario EVEREADY HOUR EVERY TUESDAY at 9 P.M. (Eastern Standard Time) 2 Broadcast through a chain of prominent interconnected radio stations. © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE @F STANDARDS. See page 33.

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POPULAR SCIENCE MONTHLY February, 1925 You have the 19 Skat BVak Seat eawe tse 4 Nak Sen UREN T SSSA wy Cote se saa’ eats ' sans WUITATITS SOS ALO ASL 4 MMM SY AY Ls A 2 ° Ost NY Hq] ee debeaeendbar bebo tiaeal iapedgaugigdad ' 4 | De Forest Radiophone Re: uires no aerial — no ground wire Batteries, De Forest Loud Speaker after delivery. Easily movable from and Tubes complete within cabinet. room to room. Unsurpassed in purity Ready to operate within five minutes of tone quality. Hear it and know. rIS} This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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1925 a ed February, 1925 POPULAR SCIENCE MONTHLY 103 radio habit now! You’d better have a De Forest HETHER you have an instrument or not, whether you know it or not, you have the radio habit already. Do you go to the theatre? Do you go to political meetings? Do you read the day’s news? Do you seek con- tact with people who offer either amusement or information? Then you’re essentially a radio fan, for many of the best of these things radio is giving in a way that they cannot be obtained elsewhere. Do you know what Lee De Forest means to radio? He is to it what Edison is to elec- tricity. Naturally the De Forest Radiophone is considered standard—and its definite advan- tages justify its popularity. (with the right dial settings) from disturbing or metallic noises. Its range is unexcelled by anything in the radio-ways! And it is an imme- diate result-getter that is simple to operate! Whatever there is in radio, De Forest can give it to you. It yields good results from the beginning and gradually increasing rcsults as your skill grows. It will pay you to look up a De Forest Agent De Forest from first to last stands for all that is substantial and thorough and fundamentally right in radio. De Forest agents are qualified to give sound and practical advice and help in The De Forest Radio- phone is a complete and self- contained instrument with a loop the size of a picture frame instead of an aerial wire, with batteries, tubes and De Forest Loud Speaker complete in one artistic cab- DV-2 inet. Here is an instrument that can be easily moved from room to room. It has a remarkable tone quality. It brings out the voice or instrument as sincerely and truthfully as the performer himself does—andclearsitself an ampere. Your Tubes are the key to your radio reception If you know what the tubes do ina radio set, you’ll know why nothing but De Forest Tubes will do. Used as detectors or am- plifiers, these tubes combine ideal operation with long life, sturdy strength and free- dom from microphonic noises. DV-2, for storage batteries, requires a filament potential of 414 volts, and has a current consumption of 25/100 of DV-3,for dry batteries, requires 3 volts on the filament, and consumes 6/100 of an ampere. The “‘Magic Lamp” of Radio radio. When you find the De Forest agent in your vicin- ity you find a man who knows radio—a man who has given us his word that he will see that every instrument he sells is thoroughly inspected and properly serviced after the sale. Avail yourself of his help. He desires, as do we, that you should get the full- est enjoyment and satisfac- tion from your instrument. DE FOREST RADIO CO. Jersey City, N. J. DE FOREST ° REG. U.S. PAT. OFF. RADIOPHONE REG. U.S. PAT. OFF. © This seal on a raaio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33

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and Light IS is the level you want for overhead work. It’s so light you can use it all day without tiring. And it’s handier to get hold of, too. You can read it from any angle, even in dim light. It’s accuracy is permanently built in at the factory—you can depend on it, year in and year out. Favorites Everywhere Sand’s Levels have made good on the job for thirty years. If you like good tools you'll appreciate the many advantages of a Sand’s Aluminum Level. 24" 6 Glass Aluminum $5.50 Others proportionately low. Also a complete line of wood levels for every purpose. Look for the Name on the Genuine At Good Hardware Stores Everywhere, or sent direct upon receipt of price and your dealer’s name and address. SANDS LEVEL ,, &°TOOL CO. 5849 Fischer Ave., Detroit, Mich. POPULAR SCIENCE MONTHLY February, 1935 of the country, es- pecially where architects of the first rank have influenced the design of small homes, it is now the custom to connect the living-room with the dining-room by means of a large plastered opening without doors or portieres. If properly designed, such arches lend simple dignity to the rooms. They make more convenient the handling of guests at entertainments and give the effect of a single large room, while affording corners for the gathering of small, congenial E “MANY sections Plastered archways like this are becoming in- creasingly popular in well-designed small homes groups. They also afford better oppor- tunities for a unified scheme of interior decoration and an artistic arrangement of furniture. By reason of their adaptability to a variety of shapes and sizes of rooms, and the ease with which they can be built, arched openings can be constructed by any man reasonably familiar with the use of carpenter’s tools. The procedure is largely the same, whether sliding doors, French doors, or single doors are to be removed in favor of the arch. In designing the opening, attempt to center it on one or both of the rooms, although this may be impossible. Balance is the thing to consider, as well as the relation of the archway to doors, win- dows, and furniture. The arches best suited to this work are illustrated. Simplicity should be the keynote, as any attempt at elaboration is almost certain to result in poor design. For most houses the ellipse is preferable. Try to make the opening noticeably narrower or wider than it is high; and take care that either the top of the arch How to Cut an Attractive Archway By Edwin M. Love ——_______ or else the “‘spring”— the beginning of the curve—will be on a level with the doors and windows of the two rooms involved, The design and location being settled upon, lay out plumb lines on the parti- tion. Cut the plaster to the line with qa cold chisel and hammer and remove to a point 2 in. below the ceiling or 1 in. below the picture molding. Then cut away the lath with a compass saw. For structural reasons it is best to make these side cutg 2 in. inside the side studs. Remove the debris, carefully punch a hole in the plaster on the opposite side near the floor, and repeat. Next, deter- mine if the ceiling joists bear on the par- tition; if they do, shore them up in both rooms by forcing smooth planks against the ceilings with two-by-fours that rest on suitable blocks on the floor. Cut the studs off on a level 41% in, above the finished height of the opening NS ELLIPTICAL BRACKET CUT FROM 14°OR SPRING OF CURVE 2°STOCK SIDE STUD BRACKETS —-J D | TRIMMER STUD ax CZ PENCIL PLASTER Se . LINE / E,-2 VF A ul b FINE WIRE OR STRING : BOTTOM PLATE ——” = er ee ke = oe i aes "UPPER PLATE FURRING STRIPS J 4 ! ' n ' 1 | 1 ' ' ‘ { ' ' ' \} ) ===--574-- Wi 4 WALL y Ps ---- PIC. MOLD, lett bee ee ee ee ee ee -\_ RETURN Two methods of framing an arch, how to lay an ellipse. and some other helpful details and remove them. Cut two trimming headers out of stock the same size as the studding, making them equal in length to the distance between the side studs. Spike them solidly together and drive up against the “‘cripples,”’ or short studding above. In case these cripples are less than 1 ft. long, it is advisable to remove them also and substitute two planks of suitable width spiked together and forced up against the plate edgewise, the trim- mer in turn being secured to it. Spike the ends to the side studs and double the latter by cutting extra studding to a driving fit under each header end. Nail all securely. The ceiling shores now may be re- moved. Using 1%-in. or 2-in. pine stock, lay out the necessary curves, ~~ = = A leet st Oe) et a le CUCU a a ee ee ee ee eee ee ee (Continued on page 126) tS] This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. an er (fh) ~S

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Y¥, 1925 Ay 2? ~ the. loors Ived, ttled varti- ith a tog velow y the ‘tural : cuts ich a . side leter- » par- both rainst C rest 4 in, ening nming as the gth to studs. ive up idding re less emove nks of forced » trim- ike the le the + to 2 Nail be re- pine curves, —— “Tt’s so Easy to Know the Outdoor Temper- ature from the Cosy Interior F Since I Purchased this Zor Temprite Window Thermometer O DRAUGHTS on Grandad N=: the baby crawling on the floor, caused by opening the doors, stepping out in the shivery weather to read the thermometer the old fashioned way, suddenly lowering the room temperature— Ijust glance through the window at my Temprite. I keep and convenience. POPULAR SCIENCE MONTHLY Possesses three essentials of thermom- eter character, ACCURACY, SER VICE- ABILITY AND ATTRACTIVENESS, In it we have accomplished our desire to create a reliableWindow Thermometer for the multitude to sell for $1.00. The Taylor Temprite is readily distinguished from'the mediocre. Don’t deny yourself the use of this distinctive ther- mometer another ing the comforts the cold outdoors MF p 1 R r where it belongs. day! It means comfort Others are enjoy- We all dress for . theweather.Idress the children accordingly for school. It’s a health factor, I feel, for the whole family. And it addsa cheery touch to our home.” The illustration at right shows this su- perior Temprite Window Thermometer full size. The printed page cannot convey the attractive appearance. Metal, white enameled back. Weather proof. Can be tread at a distance of 15 feet. Large clear numerals and markings, fadeless colored liquid in a magnifying glass tube. Comes with window brackets and nails for easy | attaching to outside window frame. Ad- justable to proper angle for reading the megpeeeeare from inside—and outside as well. Canadian Plant: Fecos BUILDING WINDOW PRIUT Iaylor Instrument Companies TORONTO AMESST.at WEST AVENUE,ROCHESTER,N.Y.U.S.A. and convenience it brings. Why not you? Easy of accomplishment—stop at your dealer’s on that shopping trip, or phone the “Mister” to bring one home tonight. You can now own this reliable Ther- mometer for a dollar—a small purchase that adds a touch of completeness to the home. If not obtainable through your regular dealer, we will ship one postpaid east of the Rockies, upon receipt of $1.00. West of the Rockies, $1.10; Canada, $1.35. Safe delivery guaranteed. To test for readability pin this advertisement up across the room. This illustration is full size. THE SIXTH SENSE OF INDUSTRY s Temperature Instruments DICATING + | RECORDING ;+ + CONTROLLING _ * eae delivery- C ompanies ochestet> N. sal Tay lo wre mp fr ite ee — aoa ee sea 1 “enclose yarantee you $ © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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106 POPULAR SCIENCE MONTHLY February, 1925 Ask such men as these —Men whose livelihood de- pends upon the quality of their tools almost as much as on their personalskill. David They'll tell you gd, ime’? _ almost with- the history of the e TadicHonmee OUt exception— the standard es- tablished by the founder ee wen that they prefer MAYDOLE HAMMERS Here’s why! There’s “hang” to a Maydole Hammer. There’s just enough crown to its face; there’s a grip to the claws that only a Maydole has; and, there’s the material and workmanship that have made Maydole Hammers fa- mous since 1843. In 1843 The head of every Maydole Hammer is of finest, press-forged steel. It costs more to make, but it gives the metal a toughness that can’t be had by other methods. Take a look at the claws—see how they’re backed off to give a perfect grip on the nail and the maximum of strength. You can “pull” any- thing with a Maydole. Then look at the handle — perfect, clear, second-growth hickory, air dried for years. And up on the head, you'll find this stamped, “DD. Maydole’”’—a pledge that it’s the best hammer we’ve learned to make in our 80 years. Ask your hardware dealer—he knows Maydole Hammers. Write us for useful handbook and catalog 23-B. THE DAVID MAYDOLE HAMMER CO. NORWICH NEW YORK 7543 — aa ti YOUR HAMMER SINCE 1843 Maydole \ ,' Y HEN sides are lined up for a good, old-fashioned snowball battle, the team that usually wins is the one best able to hurl over the ammuni- tion. This depends upon the supply as well as the accuracy of throwing. The press __ illus- trated has been de- signed to turn out rough-shaped snow- balls in large quanti- TIE — [fea] “8X3 Le 2h bade HINGED END ties. As they are piled up, the men doing the actual throwing can press them quickly into sizable use and hurl them at the opposing side. One man with a press can keep half , a dozen combatants * supplied with poten- tial snowballs for de- fense. To make a press, first choose three round cocoanuts and saw them in half. Remove the meat and set the shells aside to dry thoroughly. Meanwhile make two levers from hard wood % in. thick and 3 in. wide. Handles Et SCOCOANUTS SAWED IN HALF So BRASS SCREWS should be shaped at one end of each anda hardwood block screwed to the opposite | end. The total thickness of the two blocks should be slightly greater than the. diameter of one of the cocoanuts. They hinge the blocks together as shown. Drill a small hole in the exact center of e ‘ each half cocoanut 44 shell, being careful to keep the proper pairs », Of shells together. . Then fasten three halves to the inside of one of the levers and the correspond ing halves to the in side of the other lever so that when the levers are closed the halves will meet ex actly. Use brass or galvanized screws, me ne S88 Oil the completed snowballs Press with linseed oil, very quickly In preparing am- munition for battle it is advisable to pile up a heap of light snow in a position where the ammunition makers will be protected. They scoop up snow in their presses, squeeze the handles together, and turn out the snowballs. Speedy Coaster Has Corrugated-Iron Bottom) OASTING sleds and double runners are always more or less expensive to build. The coaster I am going to de- scribe, however, is one that can be con- structed very cheaply. The running surface is composed of a sheet of old corrugated-iron roofing nailed to a flat board surface with the seat mounted just above it on two blocks. It is steered by means of a “‘rudder” ope- rated by a steering wheel mounted at the front. The wheel can be picked up for a TOP BOARD 12'x9'-0" IRON-SHOD RUDDER of clean-surfaced corrugated iron to the} under side so the corrugations run length- wise. Use flat-headed nails and drive them through the hollows of the iron. — When it comes to turning the iron up the sweep of the forms, bend it gently and nail frequently as you go along so that it will not crinkle or have sharp breaks in the corrugations. Next, spike two blocks to the frame as supports for the seat board. These should be at least 12 in. high and well fastened. The few cents at any second-hand auto yard. This coaster is especially fast and it must be steered with caution be- cause of the long run of the bottom. With four or five passengers, it will be found a steady and speedy conveyance and one that will furnish lots of fun for the builder. The foundation for the iron is either one board 18 in. wide and 9 ft. long or, better and cheaper, two boards cleated together. Cut out four curved forms as indicated from good, strong wood about 10 in. wide. Cut a notch at the front end of each, as shown. Nail the four forms to the edges of the bottom boards and connect them in the notches at the front by means of a cleat. Then turn the frame over and nail a sheet FORM 30° LONG BOTTOM BOARDS Sy a seat is a plank 12 in. wide and 12 ft. long, with the corners beveled off as a finish. Nail it to the blocks so The sled and that the front end er comes flush with the cleat across the ends of the forms, to which it also should be nailed. The coaster is steered by a “rudder” made of strong wood of the shape indi cated. The bottom edge should be shod with strap iron and the back edge fitted with a shaft to fit in two holes, one in the bottom board cleat and the other in the seat. An iron tiller rod is forced through the center of the rudder. Make a wooden drum and fasten it to the shaft of an old auto steering wheel. Then run strong lines from the tiller ends and after connecting them make several turns about the drum. © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. Feb

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POPULAR SCIENCE MONTHLY The World’s Wonder Set at a Popular Price Manufactured and Guaranteed By EAGLE RADIO CO. Makers of The Famous Models A and B EAGLE Neutrodyne Receivers Your protection for quality and unsurpassed VALUE | Ask the dealer—he knows EAGLE RADIO CO. 16 Boyden Place, Newark, N. J. © the tiller em make @ This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS, See page 33.

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108 Power to Turn ’em You can depend upon a sturdy Snap-On to turn the most tightly ‘frozen” nut. There’s a_ special Snap-On handle fast work in every hard-to-reach Snap-On engineers have made an individual selection of Snap-On handles and sockets for each individual make of car. This is the Ford Set. A diagram in the lid of the box shows the different nuts and bolts each wrench will reach and turn. Just follow the diagram and repairs on the Ford are made easy. Write for full information about the selected Kit for your car. Look for the name—without it no wrench is a genuine Snap-On Snap-on INTERCHANGEABLE Socket Wrenches Snap-On Wrench Co., Mfrs. Milwaukee, Wisconsin DISTRIBUTORS MOTOR TOOL SPECIALTY CO. 14 E. Jackson Blvd., Chicago Gentlemen: Please send me full particulars about Snap-On Kit © GOR. sn eesecescscesessecesescscecs . (If interested in idosnn Mechanic’s Kit for all cars ra here) Smee PRE OHER EE R HEE EEEHHHEEE EHH HEHE EEE H EEE EH EEe SOPHO HEHEHE HEHEHE HEE SE EEE EE EEE EEE SEES POPULAR SCIENCE MONTHLY February, 1925 combination for | Fiacilyy Worked Shoot Lead Used to Ornament Treasure Chest artist, whose work is well known to the readers of POPULAR SCIENCE MONTHLY, there was a table that always had a rather bare and forlorn appearance amid its rich and colorful surroundings. |: THE studio of a certain New York “Do you know what I think that table needs?” the artist remarked to a friend one day. “It needs a pirate’s chest, brimming over with old jewelry, coins, and stones.” Instead of going out and buying a jewel case or an ornamental box to carry STUD-NAIL EFFECT With — sonata | SHEET LEAD WN IMITATE IRONWORK The hand-wrought metal on this chest is sheet lead fastened with cut gimp tacks out this idea, the artist hunted around and found an old oak sketching case of about the right size. He removed the partitions, cleaned out the inside, re- placed a missing hinge, and fastened a heavy brass chain to hold the lid from flopping backward. Next he visited a plumbing shop in the neighborhood and bought some thin sheet lead. At a hardware store he ob- tained a supply of gimp tacks. Returning Hammering down the background of four box corners, made in one piece for convenience to the studio, he placed the box on the sheet lead and marked out the dimen- sions, as if he intended to make a metal case to cover the box. On the lead he then sketched a design like that illustrated in the upper drawings on this page and cut out the openings with an old pocket-knife and scissors. The sheet lead was laid over the box and hammered gently in place. Where the edges came together, the metal was peened to make an almost invisible joint. Gimp tacks were driven in to hold the lead. The woodwork was painted a dull but glowing vermilion. Green, blue and This gorgeous pirate’s casket is an unusually brilliant table ornament brown artists’ oil colors were daubed on the lead itself in hit-and-miss fashion, and then rubbed partly off to give it an antique tone. The casket was lined with royal purple velvet and filled with old jewelry and trinkets, which were allowed to over- flow onto the table. So attractive and unusual was this ornament that visitors to the studio in- variably exclaimed when they first saw it. Yet the work and cost amounted to very little, and the chest could be duplicated easily by a handy. man. Another method of decorating hoxes and chests is to apply corners maa2 es shown in the lower illustrations on this page. The design is worked out on paper full size and traced by means of carbon paper on thin aluminum, brass or copper. One of the simplest ways of bringing out the design is to recess the background by hammering depressions of uniform depth into it with a punch. The metal should be firmly fastened to a waste piece of board while the hammering is being done. The final step is to cut out the design and fasten the corner strips in place with brass or copper nails or escutcheon After the de- sign is worked out with ham- mer and punch, the corners are cut with old scissors (at left) Fastening a chest corner of thin sheet aluminum in place with up- holsterer’s small nails (at right). Sheet brass or copper may be applied in the same way pins. The corners then may be connected with longer strips, which bind the edges of the box. These may be combined with various types of central ornaments and bandings cut from the same metal. © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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ary; 1925 ubed on lion, and 1 antique th royal | jewelry to over- was this tudio in- st saw it. 1 to very iplicated ig boxes maa2 2s ; on this on paper f carbon r copper. bringing ‘kground uniform he metal ste piece ing done. 1e design lace with cutcheon the de- s worked ith ham- 1d punch, rners are with old s (atleft) onnected he edges ombined naments metal. POPULAR SCIENCE MONTHLY 209 February, 1925 yon the others have their card games— Grandpa settles down to real amuse- ment—at the radio. His dependable Brandes, * Headset shuts out the bab- \’ 2 ble. Its Matched Tone gives po him each word clearly— with identical tone and equal volume for both ears. Grandpa’s in a world of his own—and the game continues undisturbed. Everybody’s happy! Table-Talker $10.00.[S0cents additional west of the Rock- ies.} In Canada $12.50. Superior Matched Tone Headset. ..-- $6.00. In Canada $7.00. Brandes The name to know in Radio © Copyrighted by C. Brandes, Inc., 1925 efor == ae ————— Gre) | © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 32

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Slow Machines Take the Count Any machine that’s running too slow or producing too slow gets ‘‘counted out’ by a Veeder Counter. Either the operator speeds up or the designer gets busy on improvements—and the VEEDER records the im- provement. Your machine must run well all the time, for its product must run into profitable FIGURES ona COUNTER The small Revolution Counter be- low registers one for a revolution of a shaft. Records output or operations of many types of light machinery; especially handy for counting the turns of radio coil winders. echanism will stand a very high rate of speed. | If run backward the counter sub- tracts. Price $2.00. (Cut 4-5 size.) Small Ro- tary Rachet Counter to regis- ter reciprocating movements of small machines, also $2.00. Speed Counter Here’s the handiest instrument for finding revolutions-per-minute of a shaft or flywheel. You hold the tip of the counter against end of revolving shaft; press lightly when the second hand of your watch comes to 0; release pressure when minute is up. A spring clutch controls the recording mechanism. (Cut less than 14 size) The Veeder Speed Counter enables you to keep motors, engines, generators, line shafting and machines operating at efficient speeds. Price, with two rubber tips, (as illustrated) $3.50. FREE—The 80-page Veeder booklet of counters you’d like to see—and set working. The Veeder Mfg.Co., 44 Sargeant St. Hartford, Conn. POPULAR SCIENCE MONTHLY February, 1925 HIS sled, painted in red or yellow and black, will be the envy of every boy in the neighborhood. It requires a little skill in fitting the pieces, but there is nothing really difficult about the con- struction, and the cost for materials is small. There is a certain ‘‘snap” and class about this racer not found in most home- made sleds. It has a cowl or dash and a comfortable padded seat patterned after the seat of a sport car. Here is a list of the materials required: ne old wash-boiler, preferably copper. hickory, ash, or elm stick 14 ft. long and 114 in. > MT hree cross pieces, 1144 by 2% in., elm or fir, 24 in. long. 4 Two cross pieces 114 by 144 in., elm or fir, 18 in. | long. One pipe collar 1 in. in diameter and 214 in. long. A length of %4-in. pipe and a quarter-turn coupling. Two washers, some strap iron for the braces, a piece of canvas and rags for the upholstering. Some %-in. ceiling or wainscoting (tongued-and- grooved strips of wood) for the floor. Three boards to make the runners. Some bolts and lagscrews of the sizes shown. Paint or varnish stain of the desired color. HOLE FOR [™, ‘i UPHOLSTERING TOWING “5 Working details of racing coaster, which has an upholstered seat and streamlined hood The main outside strip is soaked for several hours or treated with boiling water and bent in the center to fit the curve fo-med by the end of the hood. This is found by cutting the wash-boiler as shown by the dotted lines to make the hood and the seat back. The rear ends of the ctrip are fastened by the last cross piece, which is notched to suit and held | with lagscrews and strap-iron corners bolted in place. THE middle cross piece is attached similarly, while the one in front is cut to fit snugly inside the curved sides. The upper edges of these three strips lie flush with the top of the outside frame. The front runner is pivoted to the split pipe so that it will move freely up and down. This pipe extends through the 1-in. pipe collar, which is set through the center of the front cross piece. Two washers, placed between the split and spread end and the collar, reduce friction. me Workshop Making a Wash-Boiler Sport Sled By Dale R. Van Horn Above deck, the 3 in. pipe is threaded (short enough to work easily when the dash or hood is in place) and a quarter-turn coupling turned on. A straight piece of pipe then is screwed in to form the tiller, After this is done, a hole should be drilled through the lower end of the coupling and the top of the vertical pipe and a small bolt put through. The top of the frame is covered with 14-in. wainscoting. The hood is attached by tacking the cut edge to the sides of the frame. The original rim or flange on the boiler gives this piece a finished appear- ance. The seat section is tacked down through the bottom. Small holes are drilled about the rim, 2 in. down and 2 in. apart. The sides and seat proper are padded with old rags and the canvas is cut to fit. The upper edge is laced in place. Drive nails at 2- or 3-in. intervals in both directions on the bottom to pro- duce a real cushion effect. The nails can be clinched on the under side to prevent their pulling out. The runners now should be put in place. Cut them as shown and cover the lower edges with light strap iron, held in place by countersunk screws. A hole is bored through the front runner for towing purposes. The two rear runners, which also are capped with strap iron, are paral- lel and attached by strap-iron braces bolted to the two special cross pieces as indicated. Finish the runners with a file until they are bright. A SPOTLIGHT can be clamped to the top of the hood, if desired, with a small storage-battery set underneath the cowl. No brake has been provided, but if one is desired, a simple strap iron, bent to the shape of a hockey stick with the end flattened and bolted to the left side, will give sufficient leverage. If placing the feet under the hood is not comfortable, set another cleat under the frame and with the ends extending 5 in. on each side, the exact location to be de- termined by trial. The canvas should be given a coat of shellac or non-injurious paint. Place a bicycle handle-bar grip on the end of the tiller, if you have an old one. © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. ae at). bee Oe’ «eb ws 60645 CUC SlCr UCUCtlUlC OCU Oe a. ee

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1 he 34. readed e dash T-turn iece of - tiller, drilled upling and a d with tached ~ A \ F ¥ coe er s of the -on the appear- down les are nd 2 in. per are unvas is laced in ntervals to pro- ails can prevent put in over the held in . hole is r towing 3, which re paral- . braces yleces as th a file ed to the , with a eath the ut if one nt to the the end side, will od is not nder the ing 5 in. to be de- a coat of Place a nd of the Music Master Gives Life to Radio Voices ORLD fame comes to singers through a mysterious something in the voice—a personal quality that grips the hearers and holds them in a spell of delight. When voices with delicate modula- tions and elusive sweetness of tone are broadcast, only a master instrument can reproduce them faithfully. Such an instrument is Music Master. Two celebrated opera stars sing the Duet of the Flowers from Madame Butterfly. Hear the quality of great- ness in their voices, as it can be heard only through Music Master. Radio impulses entering the sensitive precision instrument in the base are - translated into sound waves, undis- torted and faithful ‘to the original voice or instrument. In the tapered tone chamber of cast aluminum these sound waves grow clear and bell-like and, finally, the full, mature tones pour forth in rich resonance through the Music Master amplifying bell of natural wood. Music Master is a musical instru- ment—the musical instrument of radio. Hear it at your dealer’s; or, better still, have one sent to your home to prove with your own set. Dealers Everywhere {Music {Master Corporation Makers and Distributors of High-Grade Radio Apparatus 10th and Cherry Streets a PHILADELPHIA usic Aster RADIO. REPRODUCER © POPULAR SCIENCE MONTHLY Connect MUSIC MASTER in place of headphones. No batteries required. No adjustments. © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. ae Mod 111 S. Ng WUSUTCS / ‘lone Quality / MODEL VI $ 30 14 inch bell MODEL VII 21 inch bell $35 MODEL VIII Cabinet Type) $ ith “Full Fl . with Fatlrieat. 93 5 eel ACS at

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It doesn’t take long to put on door hinges, or to do any work where screws must be driven, if you use a “Yankee” Ratchet Screw-driver. Ratchet Shifter— Right, is Na i Adjust- ment f Fast work with a “YANKEE” Ratchet Screw-driver And easier work, too. One grip on the handle is all that is needed, then turn to and fro, and the “Yankee” Ratchet does the rest. No tiresome grip-and-let-go. The Ratchet takes hold going forward, and re- leases coming back. It does the work and saves your muscles. Once you have used a “Yankee” Ratchet Screw-driver you’ll never be without it. No. 10 (Illustrated) comes with 2, 3, 4, 5, 6, 10 and 12 inch blades. No. 11 is same as No. 10 except that Ratchet Shifter moves across instead of parallel with blade. No. 15 has knurled thumb turn, comes with 2, 3, 4, 5, and 8 inch blades. The knurled thumb turn lets you start little screws with thumb and forefinger. Some other ‘“YANKEE” Tools Spiral Screw-drivers Automatic Push Drills Ratchet Hand Drills Ratchet Bench Drills Dealers everywhere sell “YANKEE” Tools “YANKEE” on the tool you bay means the utmost in quality, efficiency and darability Write for FREE “Yankee” Tool Book NortTH Bros. Mrc. Co., Philadelphia, U.S. A. “YANKEE™ TOOLS Make BetlOv Mechanicy POPULAR SCIENCE MONTHLY Steps and St OR use around the home, office, or fac- tory, portable steps made as illustrated are often useful. The han- dle saves stooping and makes it easy to carry the steps in one hand. A small stool also has many uses. The legs of the one shown at the right are sawn out at one time from two boards tacked to- gether. All the angles, except those at 45 deg., are laid out with one setting of a_ bevel square. The inner end pieces are cut with the grain at right angles to that of the legs and they are nailed to the itll == If plenty of nails are used, this Use center piece and then to the } The top is nailed in place last of aj) construction is surprisj strong.—C. F. GOLDTHWarr, 1 24 bytes] Portable steps (at left) and sturdily _—_ con. structed stool (above) Toy Ice-Boat Sails as Fast as the Wind. AILING a model ice-boat is a fascinat- ing diversion from the more ordinary winter sports of skating and hockey. To build a toy of this kind, construct a frame of two pieces of wood, one 3¢ in. by 1% by 10 in., and the other 34 by 1% by 24 in., lapped and nailed together to _ form across. Drilla ==. Yj-in. hole 9/16 in. deep into the frame to take the mast. With two flat-head screws attach a wooden block 1 by 2144 by 7 in. to the frame at the rear and drill a %-in. hole for the rudder post. A ¥\-in. dowel stick, 16 in. long, serves as a mast. Two grooves are made in it as guides for the screweyes in the ends of the gaff and the boom. Three holes then are drilled near the top of the mast about 3¢ in, MAST 1S 1/4" DOWEL 16" HIGH RUBBER WASHER = —S- =: ? Gi inn, SS iS >= i 1 i bord Ya er2e SS / 6 x116K10" xolenn7" — RUNNER HINGE The completed toy ice-boat and detail of the angle-iron connection for each runner apart from each other. These are for fish- line ‘ropes’? and wire guys. The mast is fitted into place with carpenter’s glue. The runners are 1 by 2 by 7 in. wooden blocks. On each fasten a 1/16-in. thick angle iron with a round-head wood screw. The angles should he attached to the runners with the base of the angles on the inside of the runners’ center lines. The runners then are fastened with No. 622 round-head ma- chine screws and nuts to 1/16-in. angle irons attached as shown to the crosspiece of the frame. The rudder is a piece of sheet iron 1/l6 by 1 by 5 in., with a brass shaft 4 in.in diameter riyeted to it. The handle is fastened to tne rudder shaft after as sembling to the frame. The rudder is kept in a fixed position for steering pur poses by the pressure of a pin in the rud- der shaft against a rubber washer. A tin cover about 4 in. in diameter is fastened to the frame to add to the realis- tic appearance of the toy. To brace the mast, wire shrouds may be run from the mast top to the outrig gers on each side, although these are not shown on the drawing. The sail is made from linen, hemmed a the edges. A brass ring 5/16 in. in diam eter is slipped on the gaff and another on the boom at the point indicated. A fisk ing line is tied to each ring and fastened to cleats. The fishing line that holds the sail in place is sewed through the sail at intervals of 34 in. and the ends ale held in slots in the ends of gaff and boom. Give the boat a coat of paint and 4 Miniature ice - yacht “snappy” name.—FRANK HARAZIM, N. Ys © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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y con- (above) id: e for fish- 1e mast is ’s glue. n. wooden On each , 1/16-in. rgle iron yund-head rew. The should be to the with the the angles inside of ers’ center he runners 2 fastened No. 6-82 1ead ma- crews and ttached as frame. t iron 1/16 ft 14 in.in handle is - after as rudder is ering pul in the rud- ier. liameter is y the realis-

rouds may the outrig- ese are not hemmed at in. in diam another on ed. A fish nd fastened that holds through the the ends are f and boom.

paint and @ RAZIM, N. Y. 33.

February, 1925 eh PTT el eli Stop right here. a billion dollars a year. Course in Practical Electricity I can quickly fit you to fill one of these big-pay jobs. I Will Train You At Home This is YOUR BIG OPPORTUNITY. Electrical Industry is the fastest growing thing in the world. But it needs more trained men—big pay men.

to

nN 6. 10. 11. **Cooke’’ Trained Men Get the Big Jobs in Electricity They get the big jobs because they are trained to fill big jobs, by a prac- tical man who has been throtigh the hard mill of experience himself. Here are some of the things that my ‘‘Boys’ get when they enroll for my course— The lowest priced, and very best home-study Course in Electricity ever offered by any one. Any course that does not give you all these things is not a complete course. z. Practical instructions by a practical engineer—a_ college trained man backed up with many years of prac- tical experience. Simplified instruction—Lessons so easy to master that lack of education or experience is no drawback. Free employment service, supervised by an expert employment man, that actually gets you the job you want. Special instruction that helps you earn exira money in your spare time right from the start. Free complete outfit of tools and electrical apparatus—not toys but real honest-to-goodness equipment that you can use in your work. Free Unlimited Consultation Service that helps you with unusual prob- lems while you are studying and afterward. Fiee Subscription to monthly En- gineering Magazine which keeps you posted on all new developments in electricity. Free use of Electrical Laboratory where you can come for actual ex- perience or to develop an idea of your own. Free Accommodations for visitirg students while working in laboratory. Free special courses on Radio, Auto Electricity, Electrical Drafting and a splendid Business Course for men who want to go into business for themselves. Guarantee of absolute satisfaction or your money refunded. Be a ‘‘Cooke” Trained man and get into the Big Pay class yourself.. Earn $3,500 $10,000 a year.

POPULAR SCIENCE MONTHLY a i Vase.“ The It is expanding at the rate of Electricity is calling you. With my Home Study Earn $70 to $200 a Week You've always had a liking for Electricity and a hankering to do electrical jobs. Now is the time to develop that talent; and make big money out of it. Even if you don’t know anything at all about Electricity you can quickly learn it through my simplified and practical method of teaching. I have trained thousands of men and put them in big-pay jobs, in all parts of the country. I can place thousands more in similar positions. As Chief Engineer of the great Chicago Engineerin Works, a million dollar institution, I know where the big jobs are and what you must know to fill them—that’s what I give you in my Course. Get ready now—let me train you to earn $3,500 to $10,000 a year. Be a Big Pai d Electrical Expert What are you doing to prepare yourself for a real success? At the rate you are going where will you be in ten years from now? Have you the specialized training that will put you on the road to success? Have you ambition enough to prepare for success, and get it? You have got the ambition and I will give you the training, so get busy. I am offering you success and all that goes with it. Will you take it? I’ll make you an ELECTRICAL EXPERT. I will train you as you should be trained. I will give you the benefit of my advice and 20 years of engineering experience and help you in every way to the biggest possible success. Valuable Book Free f 4 CHIEF ENGINEER / COOKE My book, The “Vital Facts” about Electricity, has started many ¢ Chicago Engineering a man on the way to fortune. It shows how you, too, can quickly ¢ Works become a highly paid Electrical Expert. I will send a copy; free # Dept. 532, 2150 Lawrence Ave. and prepaid, to every person answering this advertisement. a ’ CHICAGO, ILL, Act Now ! Good intentions never get you ¢@ Dear Sir: @ anywhere. It is action, alone, # y u may send me, entirely free that counts. NOW IS THE TIME TO ACT. Mail the ¢ and fully prepaid, a copy of your coupon NOW. e [ book, The “Vital Facts’’ about Elec- ¢? tricity, and particulars about ° your L. L. Cooke, Chief Engineer a ’ your special free features. Home Study Course in Electricity and CHICAGO / Nain@~.c<s<sus ene er weeee ENGINEERING WORKS 4 Pia 2150 La ce Ave., Chicago, U.S.A. / PROS bid ches dsetes ees oe ou Dept. 532 oo @ie,... ih Mees pee ae

The Cooke trained man is the Big Pay man © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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¢ ‘Red Devil’’ Pliers perenr First Choice There are many pliers, and many different makes. You want to be sure you get the styles best adapted to your purpose, that you get properly made pliers, that they will do exactly what you want them to do, and will last for years. Look at the workman- ship—see that the han- dles fit the hand snugly, and do not pinch—try the wire cutters, and see if they are properly set. The “Red Devil” trade mark is your assurance that every one of these points has been prop- erly looked after, in the design and manufac- ture, “Red Devil” Extra Heavy Slip Joint Plier No. 1226, 7 inch size, $1. 58 each. “Red Devil’’ Adjustable Wrench A most con- venient tool for all-around use- fulness. Gives better leverage than the old style monkey wrench. Sturdy forged steel jaws will not spread. No. 90—sizes 4, 6, 8, 10 and 12 FS] inches. 8 inch size, 80c each. No. “Red Devil” Tools are on sale at all hardware dealers—if not in stock send dealer’s name and order from us. Mechanic’s Tool Booklet FREE Smith & Hemenway Co., Inc. Mfrs. of “Red Devil’ Tools - 264 Broadway, New York, N. Y. “‘Red Devil’? Rapid Boring Auger Bits are 331% fo easier boring, have 10% greater clearance, and bore ath wey or against the Style 2400—10/16 here. 80c. orain r / any wood. in. shown — POPULAR SCIENCE MONTHLY different styles of © HE bench in my garage isn’t of much use,’’ Frank Robey, a neighbor of mine, remarked one day. ‘‘It always seems to be on the wrong side or end of the car. It gets in my way when I am washing the car with the hose, and whenever I work outside, under the oak tree, the bench might as well not exist at all.” ““Why don’t you make yourself a port- able bench?” I suggested. As a result, Robey designed and built the tool-cabinet bench illustrated. It is The portable bench and details of its construction TOOL BOARDS &—- LOCK PIN portable; it has a small but serviceable working space on top that can be reached from every side, and the tools, while instantly accessible, can be locked up. One advantage of the bench’s triangular Tool Cabinet Combined with Bench shape is that the casters find an even resting place on the floor or ground any- where. The tool boards, which form the sides of the cabinet, are pivoted at their centers so that they can be turned completely around to expose the tool equipment. The top is hinged to allow access to a compartment underneath for small tools and parts. Under the lid are three small lockpins, which hold the tool boards shut. When these pins are in place and the top is locked, the cabinet cannot be opened. A small bench vise is placed at the hinged edge of the top so that it does not have to be lifted any considerable distance when the top is raised.—G. A. L. OW to Construct a Machinist’s Tool Chest’? and “A Nail and Hardware Cabinet’’ are two articles on shop equipment scheduled for early publication in the Home Workshop. © pttecerral recently arose in a tech- nical laboratory to install an alarm clock. Although the best grade of alarm clock was purchased for the pur- pose, its nickel fin- ish did not har- monize well with the elaborate ma- hogany fittings of | the balance of the apparatus. The clock was an eyesore until This homemade mahogany case is designed so that the clock may be wound and set easily Neat Case Camouflages Alarm Clock the chemist in charge designed a ma- hogany case to hold it. The back is fastened to the wall by two wood screws. The front is hinged to the back and carries a spring catch. When the case is closed, the clock is held, firmly in place by the pressure of two small felt-covered blocks. Both the alarm feature and the excel- lent timekeeping qualities of the clock, together with its moderate cost, are combined in an article that at a short distance would be taken for a high priced chronometer in its case.—CaptT. S. P. MEEK, U.S. A., Philadelphia, Pa. Ornamental Desk Eraser N ORNA- MENTAL eraser holder can be made from your favorite pocket knife after its or- dinary usefulness is over. Remove the rivets, lift out the old or broken blade ends, the springs and the com- partment dividers, and fasten a round typewriter eraser at each end.—J.E.N. a © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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losed, y the locks. excel- clock, , are short priced 8. 3 com- round 5 . N . February, 1925 HIS advertisement is published to tell you three things everyone interested in Radio should know. That we believe Ward’s is today the greatest Radio store in the world —that it is the real Headquarters for Radio. Second, that at Ward’s you can buy everything in Radio without pay- ing the usual ‘‘ Radio Profits.” Third, that this big 68 page book —a genuine reference book on Radio —is yours free for the asking. Our Radio Experts This Catalogue is a book gotten up by experts. It shows all the best hook- ups, everything in parts and com- Headquarters for Radio POPULAR SCIENCE MONTHLY Write today for your FREE copy of — Ward's New Radio Catalogue 115 plete sets—so simple that you your-) self can easily install them. And it shows only tested and ap- proved Radio equipment—selected by our Experts who are up-to-the- minute in Radio. You can just as well have the bene- fit of our expert knowledge of Radio. Write for Ward’s free 68 page Radio Catalogue and see the low prices. Our 52 Year Old Policy In buying Radio from Ward’s you are buying from a house whose re- liability is above question. For 52 years we havesold quality goods only. Address our house nearest you. Dept. mi | uA | . MA \ Weal, | \\ ee ” Satisfaction guaranteed or your money back. St. Paul © Chicago Kansas City -Montgoméiy Ward &Co. The Oldest Mail Order House is Today the Most Progressive Portland, Ore. AW al —————} Oakland, Calif. Fort Worth © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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ALL-AMERICAN = Guaranteed Radio Products Power Amplifying 5 eee (Push-Pull) Input type R-30......... $ Output type R-31...,.... Rauland-Lyric A laboratory grade audio transformer for music lovers. R-500..... $9.00 } Universal Coupler Antenna coupler or tuned r. f. —- R-140...... $4.00 Self-Tuned c=) x R. F. Transformer Wound to suit the se 2 R-199 $5. 00. R-201A$5.00 Long Wave Transformer (Intermediate Frequency) (15-75 ke.) R-110......... $6.0 10,000 Meter(30kc.) Transformer Tuned type (filter or input). R-120. .$6.00 Radio Frequency Coupler (Oscillator Coupler). R-130 $5.00 Super-Fine Parts Consisting of three R-110’s, one R-120 and one R-130 $26.00 The Radio Key Book The most valuable book of radio facts ever published, contains prac- tical helps and tested hook-ups. Sent for 10 cents, coin or stamps. POPULAR SCIENCE MONTHLY yp Standard Audio Fre- quency Transformers in any radio re- ceiving set mean but one thing—assured efficiency in amplification. Since 1919 ALL American Audios have answered the de- mand for an instrument that could be relied upon for maximum amplification and faith- ful tone reproduction. Set builders who know radio do not experiment—they specify ALL-AMERICANS. Precision- Made At-American reliability is a natural result of ALt- AMERICAN precision manufacture. Special machinery and testing equipment assist in achieving perfection. When you are buying a new set, look under the lid for Att-AmMerICANS—or install them in your present set if they are not already there. You'll appreciate the difference in amplification. 3 to 1 Ratio, $4.50. 5 to 1 Ratio, $4.75. 10 to 1 Ratio, $4.75. All-American Reflex Complete receiving sets, with all instruments mounted on a and baseboard ready to be wired. Clear photographs, lueprints anda 48-page instruction book make wiring so easy as to be the work of only one delightful evening. All-Amax Junior is a one-tube set with remarkable selectiv- ity and volume. It tunes out the locals and gets real distance, or it brings in the local stations on the loud speaker. All-Amax Senior is a three-tube set with three stages of r. f. amplification, crystal detector and two stages of audio. It is highly selective and brings in the far-distant stations on the loud speaker. All-Amax Junior (semi-finished) . . . « + o « SUD All-Amax Senior (semi-finished) 00 ele ee RAULAND MANUFACTURING CO. PIONEERS IN THE INDUSTRY © 2668 Coyne Street Chicago, U.S. A. The-Largest Selling Transformers in the World HIS tricky coaster seems to be a purely French-Canadian invention, seldom seen outside Quebec Province. It is made of the front half of a ski, usually found among winter equipment in the cellar. Its length will depend upon the size of the user—4 ft. as a rule, The upright is a bit of soft wood about 3 by 4 by 16 in. screwed on through the bottom of the ski about 1 ft. from the back. A piece of smooth board about 14 in. long then is screwed crossways on the top of the upright. A coat of varnish greatly improves the appearance.—Ep- MUND L. NESBITT, Quebec, Can. Small Soldering Copper Useful in Radio Construction OR radio work and other small solder- ing jobs many makeshift soldering coppers are used. Most of them are open to the objection that the tinning burns off too easily. I find this difficulty is overcome by making a copper, as shown above, from a disk about the saine diameter as a Cana- dian penny. The disk is folded alohg its center over the piece of wire and fas- tened with a small rivet. The other end of the wire is inserted in a suitable handle. The copper then is pointed, smoothed with a file, and tinned.—W. E. Bicycle Spoke Forms Substitute for Jeweler’s Screwdriver oe tightening the bows of spectacles or the screws that hold a watch move- ment in the case, or other small screws, it is necessary to use a jeweler’s screwdriver. If one of these is not at hand, a substitute may be made from the spoke of a bicycle wheel. Cut it off as BICYCLE [ shown, hammer salatie : the wire end flat, =| bevel it back about 3% in., then file to the desired shape and size. No heat is necessary, as bicycle spokes are a good grade of steel. — Roy C. BRADBURY, Eliza- beth, La. l._—-3 {AFTER HAMMERING FLAT, FILE TO SHAPE CUT OFF HERE AND HAMMER FLAT _ on A screwdriver for minute work IS] This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33 Feb! C ~~ Qa, ¢a™ BBY

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? J} \ on, a, ski, ent ond ule, out the the , 14 the lish ED- ful der- ring ypen urns » by ym a ana- g its fas- end ndle. thed ‘ute acles \ove- vs, it iver. itute cycle [ as nmer flat, ‘bout le to shape heat , as s are le of r i pliza- ee rebruary, 1925 \ Comical Boxing Dolls Made of Putty, Lead, and Wire By Kenneth B. Murray OXING dolls that are comi- eal in action and certain to cause hilarity in any company of chil- dren or grown-ups, can be made quite easily. j \ | A white and a ee colored boxer, pos- & sibly representing Dempsey and Wills, make a lively and mirth-provoking pair. Because they are made with spring-steel wire, their arms swing back and forth in a menac- ing manner for half a minute at a time whenever the two fighters are pushed to- gether. To make the dolls, you will need putty, lead, spring wire, eye- brow pencil, and Big. 1 (above): Inserting springs into the putty Fig: 2. The features are modeled with a knitting-needle lipstick. The putty is molded into the shape of the trunks, gloves and heads. The wire should be cut to suitable lengths, bent, and inserted into the putty while the latter is soft (Fig. 1). To shape the features, use a pointed instru- ment such as a POPULAR SCIENCE MONTHLY The Drill with the unbreakable Ratchet USKY, handy, compact, easy-working, trouble-proof—that’s this Goodell-Pratt ratchet hand and breast drill. The big feature is the perfected, never-fail ratchet mechanism. The strength of the ratchet is due chiefly to the fact that the teeth are broached on the inside of the drop-forged crank hub, then case-hardened. The dogs are of hardened steel and so located that the force is almost entirely compressive — there is almost no shearing action. Ratchet is both right and left hand—operated by turning the knurled ratchet dial. This drill has two speeds, controlled by turning the shifter knob. Steel spindle runs in ball bearings. Polished hardwood handle, and side handle. The all-steel chuck has three hardened jaws for holding round shank drills 0 to 34 inch. Other tools for the home workshop In the Goodell-Pratt Catalog No. 15 are shown many other essential tools for the mechanic. Write for it. A GOODELL-PRATT COMPANY GREENFIELD, MASS., U. S. A. oolmith Makers of Mr. Punch Here is a diagrammatic illuse tration of the Goodell-Pratt Improved ratchet mechanism patented September 16, 1924. The teeth are broached on the inside of the drop-forged crank hub. The hardened steel dogs are so located that the pressure is almost entirely compressive, rather than shearing. u A pair of boxers and four heads colored with lipstick and eyebrow pencil Fig. 3. knitting-needle (Fig. 2). The lipstick and eyebrow pencil are used to give color to the lips, cheeks, hair and eyebrows. The feet, to keep the figures upright, are made of lead. A chunk of this soft metal can be pounded and squeezed to a suitable shape with hammer and _ pliers. Figure 3 shows the completed figures and several types of heads. | | | | | | 1500 GOOD TOOLS @ This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. 117 4 259 Ratchet Hand and Breast Driil Price $6.00

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POPULAR SCIENCE MONTHLY The tools of national service The American people lead the world in the efficiency of industry. Who can say what part of their success is due to the superior implements they use. This much we know. They have the world’s best telephone system as an instrument of communication, and they use it without parallel among the races of the earth. To this end our telephone service must be equipped with proper tools. The tools of management. Bell System executives, rising from the ranks of those who know telephony, must share our respon- sibility to the public, most of whom are telephone users, share- holders or workers. | The tools of service. The national, two-billion-dollar Bell System, handling fifty-eight million telephone calls a day, must be enlarged and extended while in use. The tools of forecast. We must continue to know the rapid and complex growth of communities and make provision in advance, so that the telephone will be ready when needed. The tools of supply. The Western Electric Company, our manufacturing and purchasing department, its factories manned by 40,000 workers, assures us that extension of facilities need never be interrupted. We must have the best tools of finance, of invention, of every- thing else, in order to continue serving the American people. AMERICAN TELEPHONE AND TELEGRAPH COMPANY 2 AND ASSOCIATED COMPANIES 8 BD BELL SYSTEM 5 One Polic y, One System, Universal Service February, 1925 GrahamMiade Two previously in- Sa, Combination Get manufacturer’s prices. | ©XPerienced men _ in Ranges Save 1-4 to 1-2 on stoves widely separated parts Ps ranges, furnaces, and | of the country make “ household goc Sim tm | this extra money for einourdyears | themselves only by en ee == oa terme on 1 fast sales and good > monthly. Money-back guarantee.24- | profit on each sale. Part Time so shipments.30 ~~—=———_— { | Ye 8” trial our / ! , cus- jorse “Ween ——— Then there is F. De- —— pries, who averages $7,000 a year, Rober of Va., whose $500 a month is very dif- ferent from the $40 a week he made at a poorly paid clerking job. We have i clerks, factory workers, salesmen and a a J others on the Fyr-Fyter sales force cashing os i in on one of the most lucrative propositions. oe A Wevreviver JO9 : % Fyr-Fyters sell like the proverbial hot cakes. We have a - * Ry PA’Ka coe vacancy for you if you have enough ambition and determi- Direct to You SS nation to write us. No experience orinvestment necessary. Address The FYR-FYTER CO., 648 Fyr-Fyter Bldg. ,Dayton,O. G PRE us f i | radiator by means © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. [* MAKING up some store fixtures for display purposes, the owner of a small sheet-metal shop had to devise a method for adjusting the stands up and down. The standards were of brass tubing and a practical. The me- chanic finally adopted the means illustrated. He slit the ex- terior section of the tubing, cut a sleeve from pipe, tapped it for a set- screw and attached it to the tubing with solder at the CLAMPING | COLLAR haa prciniin side opposite the setscrew. The same method could be used for holding drills when a chuck is not avail- able, or in connection with a tool handle for miscellaneous uses. Extra Water Pan Improves ‘‘Pipeless’’ Heating Plant N A hot-air heating system, especially the pipeless type, the usual water pan seldom supplies sufficient moisture. Real- izing this, the writer tried out various schemes for increasing the moisture in the heated air. The method eventually adopted gives 2 maximum of moisture and the water pan is filled without going down cellar. The humidifier can be installed quickly by any one handy with plumber’s tools. It will prove a paying investment in better living conditions and reduced fuel expense, because a high humidity means that less heat is required to keep warm. Lift the center of the floor register so the heat radia- tor of the furnace is exposed. With an iron strap fas- ten a good-sized water pan over the center of the WATER SUPPLY PIPE, ; STRAP-IR of machine screws. BRACKET WATER These can be An extra large fur- threaded into holes nace humidifier tapped in the top of the register. Placing a bit of furnace cement on the screw before threading it in will check any possible escape of gas. Next, cut two small holes through the two casings of the furnace, close under the floor. Attach a \%-in. pipe to the main water pipe, run it through the casing and lead it down to the pan as shown, by means of elbows and short lengths. Insert a valve in the line at a point where a turning rod can be brought conveniently through the floor and operated from above. Be sure and provide a key or other safeguard so the valve cannot be turned on accidentally and the furnace pit flooded. The pan can be watched during filling by looking down through the floor register.—L. R. ——_—_—_—_—_ ae nail sav! It i tha pla in | rail Cal av cut 0d see nu

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or all od la ot ace g it gas. the ider the sing , by ths. here ntly rom r or t be nace shed ugh ‘Clamp Holds Voltammeter on Face of Radio Panel F YOU use a voltammeter in connec- I tion with your radio set, you can keep it handy by mounting it on the panel as shown below. Cut out the clamp with tinner’s snips from 1/16-in. sheet brass and drill the center hole, countersinking it to take a | flat-head machine screw. Bend the arms | ~ PANEL OF RADIO Set: % \\ i, / Pocket voltammeter on radio panel and details of the holder so as to grip the voltam- meter and fasten the holder to the panel wherever convenient. Two binding posts and two small angles are used for making contact with the volt and ampere terminals; the third binding post, which is common to both sides of the meter, is connected behind the panel with the screw that holds the clamp.—PHILIPPE A. JUDD, Portsmouth, Ohio. Light, Handy Nail Box Made ‘from Old Tobacco Tins ADE from empty 14-lb. tobacco tins with rolled edges, the combination nail box illustrated is a handy and time- saving container for the home workshop. It is useful also for carpenters, especially finishers on trim 18X15 X7" and interior wood- / work. TIN Sp The baseboard BOXES cr p is nailed to the handle stick, as | ) shown, and _ the Pa Sad | tins are nailed or | PEA ‘ screwed to. the “eo 4 i base. A nail | a through the top of i Zz each tin into the LB handle further re- =e inforeces the con- BOARD %4X 8X8 struction. An aid in keep- Several of these ae eet containers may be : made, or more than four tins can be placed on a single base if preferred. Provide a convenient place to hang up the nail boxes when not in use and don’t leave them out in the rain—R. M. REKERT, Regina, Sask., Canada. Fitting Tool Handles Quickly with a Grinding Wheel Mec# laborious whittling and shav- ing on hardwood handles can be avoided and a snug fit easily obtained by cutting down the handle to size on a Coarse grinding wheel. This method seems to be little known, judging from the humber of men who use a slower method. | iin POPULAR SCIENCE MONTHLY Mechanics Know They Measure Closer With a BROWN & SHARPE —Accurate Graduations— Examine a Brown & Sharpe Micrometer. Notice how accurately the graduations on the thimble line up with those on the barrel. Turn the thimble. See how easily and accurately the clean cut graduations can be read. Or study a Brown & Sharpe Vernier or Protractor,—the excellence of its graduations is instantly apparent, — visible evi- dence of the superior workmanship which goes into all Brown & Sharpe Tools. bi Superior graduations are only one feature of the mechanical excellence of Brown & Sharpe Tools,—a real excellence which makes them do better work for the man who owns them. You ought to have Brown & Sharpe Small Tool Catalog No. 29 which lists over 2,000 of the best tools you can buy. It’s sent free to any address. Brown & Sharpe Mfg. Co., Providence, R.I1., U.S. A. BROWN §&} SHARPE TOOLS “Standard of the Mechanical World” © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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Swivel Base Clamp Base “A SK your hardware dealer to show you these new . Pexto Bench Vises—they have new patented construction and are made from new patterns thruout. These Pexto Vises are made in sizes 13” to 3” jaws, with clamp or swivel base, iron or steel faced jaws—in fact you will find just the style and size to meet your require- ments. They are attractively fin- ished in gray with polished jaws and anvil. Your dealer can show you these Vises along with other Pexto Me- chanics’ Hand Tools—tools that you need in the home or garage—such as Braces, Bits, Hammers, Hatchets, Pliers, Wrenches, Chisels, Draw Knives, Snips, etc. Another thing—you can’t go wrong on Pexto Tools as they are backed by a century of tool making experience and are a combination of skillful workmanship and materials of quality. ° ‘Worth WhileTools PECK STOW & WILCOX CO. SouTHINGTON. Conn. POPULAR SCIENCE MONTHLY The Home Workshop Building an Aerial Mast that Requires No Guy Wires ‘THE radio fan often can improve the volume and range of his receiving set to the equivalent of one or two addi- tional tubes by constructing a fairly high outside aerial. The only problem to be solved is in the erection of a neat, strong mast for sup- porting the far end of the antenna; the near end can be fastened to the house. One of the best masts is that illustrated. Although 28 ft. high, it is easy to build, costs little for materials, requires no guy wires, and is much more workmanlike in appearance as well as cheaper than a solid wooden pole of similar height. The fact that it resembles in appearance the steel 10" SQUARE ip TOP { 6"DIA POSsTA| apg aes Al || BRACES) O25 square BASE ( N (SS WK2KIGLOL > || onal NI snore ; i "gt aE p= “ET concRETEN” Y} N = Rough spruce shingle laths, 16 ft. long, are used in constructing this rigid antenna pole work commonly used for supporting the aerials of broadcasting stations is another point in its favor; it is distinctively a radio mast. To build it requires 20 pieces (two bundles) of 1 by 2 in. by 16 ft. rough, common wood (tough spruce shingle lath preferred); afew odd boards % in. thick; one stock flagpole about 2 in. in diameter at the base and 12 ft. long; one stock 6-in. fence or laundry post about 10 ft. long, of chestnut or other wood that will not rot readily in the ground; 3 lb. eight- penny common nails, bottle-green paint sufficient for two coats, one small galvan- ized iron pulley (if the flagpole is not equipped with a good pulley) and 50 ft. of sash cord. On a sidewalk, floor, or level ground lay one 16-ft. shingle lath, and butt up against the end of it a piece 4 ft. long, skew-nailing the two together temporar- ily. This is to form one side of a sort of ladder that is to be 20 in. wide at the bottom and 10 in. wide at the top. For (Continued on page 121) IS] This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. No. 8 or No. 26 Bent Nose No. 10—Thin Nose VERYWHERE about the home —from cellar to attic, from kitchen to garage—you will find need of a good Slip Joint Plier. There is a style of Slip Joint Plier in the extensive Pexto line to meet your requirements—ask your dealer to show them to you—twenty styles in all and all practical sizes of each style. They are drop forged steel, carefully finished and can be had either Nickel Plated or Blued finish. All Pexto: Tools are backed by a century of tool making experience. The line consists of Bit Braces, Hammers, Chisels, Screw Drivers, Hatchets, Snips, Squares, Wrenches, Pliers, and many other small tools and it is easy to procure Pexto Tools as they are carried by practically all progressive dealers. Ask for Plier Booklet. : Worth While Tools PECK STOW & WILCOX CO. SouTHINGTON, CONN. f renensed

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Nose home from ll find - Plier meet dealer styles F each steel, > had finish, ed by rience, races, rivers, nches, | tools Tools lly all tei ina an ‘| cement. The Home Workshop Building an Aerial Mast (Continued from page 120) the other side of the ladder use two sim- jlar pieces, but put the 4-ft. length at the opposite end from the one on the ladder leg already made. About 1 in. from the bottom nail a 4-in. batten (or two laths) at right angles to the center line. Cut the first diagonal brace about 3 ft. long, sawing the ends at the correct bevel and making both ends alike. Lay this brace on the frame at the bottom, keeping it back from the edges % or 1 in., according to the thickness of }the wood. Do not nail this, but mark and cut the next one, maintaining the same bevel cut. Lay this in position and con- tinue until all the pieces are cut. If the same bevel is maintained, it will be found that each piece will be shorter than the preceding one. Before nailing these in place, mark three more sets. Two eightpenny nails at each end of each brace will be amply strong enough if the nails are well clinched. All four frames are made exactly alike with the exception that the diagonals start from left to right on two of them and from right to left on the others. In other words, they are made in pairs. Nail three sides together on the ground, overlapping only one corner of each side, so that the mast will come square. UT from a %%-in. board two pieces 9 in. square and nail them together so that the grain ot one crosses that of the other. Fit the square in place at the top of the mast, cutting out two diagonally opposite corners to allow for the ends of the top braces. Then bore the piece to suit the flagpole and fasten it about 3 in. below the top of the mast. Make a similar two-ply piece 11 in. square to fit within the sides of the mast about 4 ft. from the top. Only the upper of the two boards in this case should be bored for the flagpole, thus forming a socket or cup. Set the pole in place and fasten with a lagscrew through the bot- tom board, but be careful not to split the pole. Also attach the pulley and line. It will save time to paint the mast before erecting it. Set the heavy 10-ft. fence or laundry post in the ground, preferably with Then you may erect the three- sided mast around the post, seeing that it stands quite plumb. Nail short braces from the four corners of the mast to the post near the top of the latter; do the same at the bottom. Also make a shelf at the bottom upon which heavy stones may later be piled for added security. The last side then may be raised and nailed in place. The mast, if properly built, will stand firmly enough to allow a ladder to be placed against it, so that it can be re- painted whenever necessary. Wedges should be used to tighten the flagpole where it passes through the top of the mast. Incidentally, the aerial can be lowered and a flag raised upon occasion. It is also possible to use the mast for supporting a Jong pulley clothesline, as the construc- tion is astonishingly rigid.—A. E. E. Se © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. POPULAR SCIENCE MONTHLY It is a significant fact that organizations that de- pend upon cutting tools most, invariably turn to Simonds— first, for saw engineering service and for general saw information and, finally, for the saws themselves. All Simonds saws are made from steel produced in Simonds plants from an exclu- “sive formula. Bring YOUR saw ‘4 problems to Cutting Tool Head- quarters. © Simonds produces solid or inserted metal tooth cutting saws, slitting and slotting saws— made with any standard style tooth to fit any machine. Pronounced SI-MONDS SAWS FILES KNIVES STEEL SIMONDS SAW AND STEEL COMPANY Fitchburg, Mass. “The Saw Makers’’ Established 1832 Branch Offices in Principal Cities

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122 POPULAR SCIENCE MONTHLY gar, The new Tungar does all the old Tungar did—and more. It will charge both radio A and B batteries, with no change except slipping the wire from one terminal to another. It charges 2, 4 or 6 volt A bat- teries—24 to 96 volt B batteries—and auto batteries, too. It is simpler than ever to use. Just two clips and a plug. No need to disconnect your battery from your set, or make any change in the wiring. The Tungar charges overnight while you sleep. And it makes no disturbing noise. It is more compact than ever. It hasa new bulb, unchanged in principle, but more convenient in size and use. G-E research has made a good product better! Keep your batteries charged with a Tungar—and get the most out of radio. 300,000 ‘Tungars already in use. The new Tungar charges both —_) A _ B bat- i tteri egg owed envome oma Tunégar—a registered trademark—is found only (East of the Rockies) $18 on the genuine. Look for it on the name plate. The Tungar is also avail- able in five ampere size Merchandise Department, Chest of the Rockies). $28 ' General Electric Company, © 60 cycles—110 volts Bridgeport, Conn. GENERAL ELECTRIC Our Catalog start | Free Shows gramentinstitati EME for free ca’ x Zi ATLAS MOVING PICTURE CO. Wea 636 S. DearbornSt, Dept. 77,Chicago for free book. Burlington company ; “WONDER” COLD PIPE, sy TUBING & BAR BENDERS A Gerstner CHEST © is valuable to ¢ MACHINISTS and HAND and MOTOR OPERATED TOOLMAKER 14 Sizes of Machines Saves its cost many What it costs to bend pipe our times in value of tools oa Ry. Ser wend. |, .. sf cante it saves from loss and eyiave 4. dis Eocente, 4°; pine SF conte Jamage. Write for free 8’ pipe $1. catalog. : Send for Catalogue. H. GERSTNER & SONS AMERICAN PIPE BENDING MACHINE CO. 514 Columbia St., Dayton, 0. 51 Peart St. Boston, Mass. February, 1925 (Continued from page 96) the stuffing into place. The reason is the same as that for tying a quilt, only with a thick cushion such as we have made, we cannot take a stitch clear through. Be.| sides, we need more strength, so we use tufting buttons, as in Fig. 7. You may have any number of buttons you choose and locate them as you desire. Regular tufting twine or strong fishline should be used. Thread a long needle ang force it through the cushion so that it comes through at a corresponding point on the opposite side. Run the thread through the eye of the tufting button and return your needle through the same holes you used before. Now thread on another button and remove your needle, In order to draw the buttons together as shown in Fig. 7, a special knot must be tied. Figure 12 shows the method. The purpose is to form a slip knot that will allow you to draw the buttons up snugly to the covering on both surfaces. How your twine will look when you are ready to tie the knot is shown at A. The short end is held in the left hand, the tong end in the palm of the right hand, with the index finger reaching out to grasp or hook this strand. This strand is shown at B drawn under the first and an upward turn begun; C shows this turn com- pleted, the loop being drawn over the top and to the left of the short end, which still is held in the left hand. Now take this left end, move over the two strands and come up through the tri- angle already formed. Notice D. The loop held by the right index finger is released. Still holding the short end, slide the knot thus formed into place and draw the buttons together. When this is done, a sharp pull on the short strand will draw out the knot in such a manner as to make a secure job. A common square knot is then tied around the shank of the button and the ends of the twine are trimmed off short enough so as not to show beyond the edge of the button. If you use buttons with a cloth shank, it will be necessary to stitch through this instead of through the eye of a hard button as described. The knot is tied in the same manner. In making a wedge cushion, it is well to cut out the front, back, and end all in one long piece. Cut the triangular ends separately and do the stuffing from the narrow edge. Starting a Cold Engine NY one who has had the experience of cranking a Ford motor for half an hour or more when the thermometer 1s around zero should make a practice of, leaving the emergency brake lever down in running position at night. This squeezes out all oil between the bands and the drums and prevents any from getting in until the motor is started again. In the morning draw the brake ‘lever back in starting position and the motor will be found to turn over very much easier, because of the absence of congealed oil between the bands and the drums.—H. W. —— © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. whitew k —E require’ F (or oth BB require cc 6 by 19 DD lar, 1 re EE require FF require wide ( If yo mill, glued will g wortl yours two « the t for al over

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hs 1 is the with a de, we |. 1. Be We use buttons desire, fishline dle and that it y point thread on and e holes nother ogether nust be 1. The at will snugly you are 4. The he long d, with rasp or shown upward n com- the top , which ver the the tri- ). The nger is rt end, ace and 1 this is and will er as to square k of the |: ‘ine are not to on. | shank, igh this a hard is tied 3 well to ll in one ir ends ‘om the 1e perience half an neter is ctice of, ar down This 2 bands 1y from d again. ce ‘lever e motor y much nee of and the Beautiful Chest Easily Made (Continued from page 94) B End of frame under top (mitered), 74 by 214 2 required. ’ by Ht ent of frame under top (mitered), % by 24% required. cha by A ack of frame el top, 7g by 134 by 36, itewood, 1 required. ; ends of case, 14 by 20)% by 3014, plywood, 2 ired. J ee Front stiles, 74 by 214 by 3014, 2 required. G Top front fillings, 1 by % by 1, 2 required, H Bottom front fillings, % by % by 314, 2 ired. A A , ee uarter turnings (stock design), 7% by 7% by 6, 4 required. : ; : ‘y Quarter round moldings, 4% by %% by 23%, 2 sired. u , , . Ce Drawer rails, 7% by 21% by 3614, 4 required. L Drawer-top division, 74 by 14 by 6, 1 re- st og-drawer fronts, 34g by 6 by 17 14, plywood, uired. p : trea Second-drawer front, 34 by 6 by 364, ply- required. eee and fourth-drawer fronts, 34 by 7 by 3614, plywood, 2 required, : ; P Drawer-front backings (used with O), 14 by 1 by 354, whitewood, 2 required. Drawer-front backing (used with N), 14 by 6 by 35 4, whitewood, 1 required. ‘ R Drawer-front backings (used with M), 14 by 6 by 1614, whitewood, 2 required. § Third- and fourth-drawer sides, 14 by 7 by 18, whitewood, 4 requ “ed. ‘ : T Top-and second-drawer sides, 12 by 6 by 18, whitewood, 6 required. U_ Third- and fourth-drawer backs, 14 by 61% by 3544, whitewood, 2 required, V Second-drawer back, whitewood, 1 required. W Top-drawer backs, 14 by 5% by 1614, white- wood, 2 required. — X Second-, third-, and fourth-drawer bottoms, Y by 18 by 35 4, plywood, 3 required. Y Top-drawer bottoms, !4 by 18 by 1614, ply- wood, 2 required. Z Back of case, 34 by 3814 by 31, plywood, 1 required. AA Drawer runners, 7% by 114 by 18, poplar (or other inexpensive wood), 10 required. BB Drawer guides, 14 by % by 18 \, poplar, 10 required. CC. Center division between top drawers, 74 by 6 by 19% (or 18 or thereabouts), poplar, 1 required. DD Division under CC, % by 2% by 1934, pop- lar, 1 required. EE Base front, mitered, 14 by 15% by 4014, 1 required. FF Base ends, mitered, 14 by 154 by 2114, 2 required. GG Feet (stock design), 4 in. long, 4 required. HA Filling for all drawers, ?g by 1% by 36, whitewood, 12 required. II Filling molding, quarter round, 34 by % by 36, whitewood, 12 required. ‘ JJ Dowels or double-end screws for feet, 5/16 by 3, 4 required. KK Drawer-back strips, 14 by 14 by 6, poplar, 10 required. Antique handles, 214 by 334, brass, 8 required (or glass. knobs). Escutcheons, brass, 3 required. Locks, % to center, 3 required (if wanted). Screws and nails; best glue. 4g by 5% by 35%, LY WOOD or veneered stock is used so widely now and is such a desirable material for the amateur craftsman that it will pay you to make every effort to obtain it for use where specified in this price seems unreasonably high, you can substitute solid stock for the top, ends and drawer fronts, and tongued-and- grooved stock of any available kind for the back. Lacking plywood for the top, you will find that you cannot get a single board wide enough to make the top in one piece. If your lumber dealer operates a planing mill, you will be able to have the top glued up and cut to size for you. This will save considerable work and be well worth while. You can, however, do the same work yourself without much trouble. Match two or three of your best pieces to make the top and bore into the joining edges for about six 3{-in. dowels. Run a plane over the dowels so there will be a narrow (Continued on page 124) en list. If, however, you cannot get it, or the | © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. POPULAR SCIENCE MONTHLY 10 Shaves Free Send Coupon We've Won Millions to this unique shaving cream; please try it—5 new joys await you GENTLEMEN: Palmolive Shaving Cream is a national sensation. flocked to it by the millions. 80% of its users once were wedded to other shaving creams. Only outstanding and superlative advantages could have won them over. Men have 60 years of mastery We are experts in soap-making. proving soap. We asked 1000 men what they most desired in shaving lather. We spent 18 months in modern laboratory work. 130 formulas were discarded before we found the right one. Then we offered men a test. And that test changed the shaving cream situation; made a new leader in the field. For 60 years we have been im- Find out—please Palmolive Shaving Cream may or may not meet your ideals. So in fairness both to you and us, won’t you put your present cream aside a few days and give Palmolive Shaving Cream a trial? Simply mail the coupon. We'll thank you for the courtesy, and you’ll thank us, we believe, for the new conception of shaving comfort that it brings. Five remarkable results Multiplies itself in lather 250 times. Softens the beard in one minute. Maintains its creamy fullness 10 minutes on the face. ; 4 Strong bubbles hold the hairs erect for cutting. delights 5 Fine after-effects, due to the palm and olive oil content. O bo = To add the final touch to shaving luxury, we have created Palmolive After Shaving Talc—especially for men. Doesn’t show. Leaves the skin smooth and fresh, and gives that well groomed look. We send a sample free with the tube of Shaving Cream. THE PALMOLIVE COMPANY (Del. Corp.) Chicago, Ill. PALMOLIVE SHAVING CREAM 10 SHAVES FREE and a can of Palmolive After Shaving Talc Simply insert your name and address and mail to Dept. B943. ddress for residents of Wisconsin, The Palmolive Company (Wis. Corp.), Milwaukee, Wis., Address for_residents other than Wisconsin, The Palmolive Company (Del. Corp.), 3702 Iron St., Chicago, IIl.

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Mint Electrica eries : they last longer ‘ousrene? IGNITOR (F&F DRY CEL! \f FOR 3 'GNiTION, RADIO /& POPULAR SCIENCE MONTHLY l Energy for— gas engineignition telephone and telegraph doorbells buzzers motor boat ignition heat regulators tractor ignition starting Fords ringing burglar alarms protecting bank vaults electric clocks calling Pullman porters firing blasts lighting tents and outbuildings running toys radio “A” accessory shops, Don’t just ask for “a dry cell.” Ask for Columbia Eveready D Batteries by name and battery efficiency. | Eveready Dry Batteries are sold by electrical, hardware and auto | dealers, radio and implement deal- | ers, garages and general stores. Columbia Eveready Ignitors can be purchased equipped with Fahnestock spring clip binding posts at no extra cost to you. et 100% olumbia marine suppl 1} WAT | tt) Ll | I i | | | | bu iu COLUMBIA Evereadys furnish power and pep for a thousand and one tasks. Every- thing from workaday tasks like ringing the doorbell and starting the Ford, to run- ning toys for the children and providing current for inventors and experimenters. For more than thirty years Columbia Evereadys have been known for their abundance of electrical energy. They are better than ever—they last longer. Manufactured and guaranteed by NATIONAL CARBON COMPANY, INc. New York San Francisco Canadian National Carbon Co., Limited, Toronto, Ontario Tool Cases for Machinists, Car- oe aa and Tool akers; none better; thirty styles. Quarter- ed oak and metal cov- ered, Ask for booklet. “Built for Service” arc rs for i today :DWIN G. GETTINS Aere mechanical Engineer, 617 E. 107th St., Los Angeles, Calif. Flies Without Motor The GETTINS OCTOPLANE Altitude Record 2020 Ft. Glide Rec Record 5146 Ft. Book giving detailed i The Pilliod Lumber Co., Swanton, Ohio instruc- tions and license under Pat. No. 1439232 enabl informa- bill, We have been making toprecoverings, side curtains and seat covers for li years. We have patterns for all makes, no model too old forus, Easy to apply, simple instructions given. Write for our big money saving catalogue with samples. 630 THE LIBERTY TOP & TIRE CUMPANY, Dept. E-8, Cincinnati, Ohio RECOVER IT $3.85 YOURSELF AND UP Make yourcarlook like Custom Made new andsave abig labor International Body Works, RADIO SETS—AUTO BODIES SEND FOR THE INTERNATIONAL CATALOG Our net price list. Full line of Radio Sets; m and auto i, bodies for F 8 y SZ Pps ig pooney by buying Direct from he % 914 W. Ohio St., . SVM AQUA Ho Beautif (Continued from page 123) flat side on each to allow the glue and air to escape when the boards are for together. Be sure not to have the dowel too long; they should be at least Y in shorter than the total depth of the hole ; ne Apply hot glue or first-class liquid glue warmed ina dish of hot water to the dowel holes and edges and force the pieces together be. tween strips nailed on the bench or the workshop floor. Use wooden wedges ty If you have regular cabinet clamps, so much the better, on each side of the joints. exert pressure. you will have no difficulty in obtaining the quarter-round molding for the The little turnings at the top and bottom are stock designs, but if you cannot obtain them o have them made specially, get turnings from a discarded piece of furniture or g new stair-baluster, or anything that yoy can adapt for use as the cap and base for front corners of the case. the quarter-round pilasters. The same suggestions apply to the feet, They are a stock design, but if you cannot buy them, get feet from a discarded piece of furniture; inquire at your local cabinet. maker’s, in case he may have something to serve your purpose, or glue up blocks of the right size and carve them out your self. Ifsome of the chisel marks show and if the four feet do not match exactly—if they are not as perfect as machine cary- From the view-. point of the furniture connoisseur, they ings—it is just as well. will be all the more attractive. In other words, to build even so simple a piece as this requires a certain amount of ingenuity and perseverance, but that is half the fun. To understand the construction, simply imagine the case with the drawers, the ends and the quarter-round ornaments all You have left a framework made mainly of strips 7% by 2) in., held If you can- not get a large sheet of 3- or 5-ply veneer for the back, you will have to strengthen the frame by adding back members, to which the back boards can be fastened, removed. together with glue and nails. AFTER the framework is complete, the end pieces are screwed on from The quarter-round pilasters the inside. then are glued in place. A frame mitered at the front corners is made for the top of the case. frame the top proper is fastened by means of screws from underneath. All these details are made clear in the working drawings on page 94. If the chest is too large for the room in which it is to be used, or if the avail- able wall space is not quite wide enough, you can modify any of the dimensions to suit, The chest may be finished to match other furniture, or in any way desired. A good method is to stain the wood and fill it with a paste filler of first-class quak ity. Give it a very thin coat of shellae and then follow with three or four coats of shellac very little thicker than the first Each coat should be rubbed wash coat. (Continued on page 125) To this —— ‘actory. Dept. 8, Chicago, IIL © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. 0! Io tube, h ‘it is 80 ‘under | Bea ‘lightly very fi ened W “wet” for th ‘coats | rubbec Aw blemis is ofte wood | almost to his know In alway: wood Better wood | be squ ‘pressic broke: When cut, or it fini: * Du afterv kinds plied chisel. any 1 paren finish. It y make soft.v it. I used | and ¢ the p: is. pre You | sary | powd and | boiles desir “iti

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them or turnings ure or q that you base for the feet, U cannot led piece -cabinet- ’mething blocks of ut your- show and actly—if ine carv- he view-. ur, they 30 simple 1 amount but that n, simply wers, the ments all amework in., held you can ly veneer crengthen nbers, to astened, complete, on from pilasters corners is To this tened by ath. All e working the room the avail- e enough, onsions to to match y desired. wood and lass qual- of shellac ‘our coats n the first ye rubbed fe DRESS farm machinery belts, an I Jowa farmer folds a piece of inner tube, heats it at the tractor exhaust until it is soft, and rubs the melted end on the ‘under side of the belts.—F. L. CLARK. _ Beautiful Chest Easily Made (Continued from page 124) ‘lightly with pumice-stone and oil, or with 'yery fine sandpaper (00 or finer), moist- ened with oil. You can obtain a so-called “wet” sandpaper that is especially good for this purpose. Finish with several ‘eoats of furniture wax applied thin and ‘rubbed in vigorously. | A word might be added on concealing ‘blemishes. Even in furniture factories it lis often necessary to hide defects in the }wood and repair mishaps. The amateur almost always has to do some “‘ doctoring”’ to his work, but unfortunately does not know how to do it successfully. In the first place, cracks and holes always can be filled with fine sawdust or wood file dust mixed with thin glue. Better than this, however, is a prepared wood paste now on the market which can be squeezed into any holes or shallow de- |pressions, and even molded to replace broken edges of carvings or moldings. When dry, it may be sandpapered, planed, cut, or even nailed into, just like wood, and it finishes like wood. ‘During the course of finishing and kinds of damages with stick shellac, ap- plied with a warm soldering iron or old chisel. Stick shellac can be obtained at any large paint store in colors, both trans- parent and opaque, to match any kind of finish. It would be quite possible, of course, to make this chest of drawers of a relatively soft wood, such as whitewood, and paint it. In that case, glass knobs might be used instead of antique pulls. Any holes atid cracks may be filled with putty after the priming coat is on. White lead putty 8 preferable to ordinary whiting putty. You can make some yourself when neces- sary simply by buying 10 cents’ worth of powdered white lead at the paint store and mixing it with ordinary putty and boiled linseed oil to the consistency ede © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. POPULAR SCIENCE MONTHLY afterward, it is possible to conceal many | N dollar-for-dollar value, the 6-D Receiver leads the field. This remarkable Receiver excels in every phase of performance — purity of tone, sharpness of tuning, range, volume and ease of operation. You can pay more, but you cannot buy better By all means, examine the 6-D before making a final selection. reception. Price $125.00 without accessories EISEMANN MAGNETO CORPORATION 165 Broadway, New York DETROIT SAN FRANCISCO SPECIFICATIONS Circuit: Two stages of tuned Panel: Aluminum, radio frequency amplitication, detector and two stages of audio frequency amplification. Non-oscillating. Tubes: Five in all. Jacks provided for either five or four tube operation. shield. Batteries: Lither storage or dry-cells. low leakage losses. | . u Cables “Complete set supplied Sockets : Suspended on cushion ' ‘ for A" and ‘B’" batteries. springs which absorb vibra- oe Wave lengths : 200 to 600 me- tions, ters, with uniform efficiency of reception, Aerial: 75 to 125 feet, single wire. batteries, WZ EISEMANN cad Ya ELECTRICAL Type 6-D Broadcast Receiver Non-oscillating ~- Non-radiating th attractive crystal black finish. A perfect body capacity Dials: Sunken design. Shaped to fic the hand and permit a natural position in tuning. Condensers: Single bearing, Cabinet : Mahogany, with dis- tinctive lines and high finish. | Ample space provided for**B” ‘A || CHICAGO git vi WANN iy i) salaeoaied ey EQUIPMENT a

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POPULAR SCIENCE MONTHLY The FAN STEEL The Balkite Battery Charger is entirely noiseless. It can be used while the radio set is in use. It has no moving parts, vi- brators or bulbs, and has noth- ing to break, adjust or get out of order. It is simple and unfailing in Tested and Listed as Standard by Underwriters’ Laboratories Balkite 2422; does not create disturbances in your set or your neighbor’s PRICE $19.50 © $20 West of Rockies, $327.50 in Canada Manufactured by FANSTEEL PRODUCTS CO., Inc., North Chicago, Iif. 0.8. Patent 1,495,582 operation. It cannot discharge, short-circuit or damage the bat- tery by overcharging. Besides charging “A” batteries it will also charge “B” batteries of the lead type in multiples of 6 cells. Sold by all leading radio dealers. it’s a Wonder! Does Everything in Woodworking Only $225: complete with motor 8 inch Circular rip saw 8 inch Circular cross cut saw 11 inch Band saw 4 ineh Jointer Shaper 10 inch sander * Jathe—14 inch swing ARKS Cabinet Shop Special is the most recent development in portable, small shop equipment. It is a band saw, shaper, lathe—all in one. You can do sawing, rabbetting, planing, moulding, matching, panel rais- ing. Just the thing for your home shop! You can order it complete or with just the attachments you want. Write for circular The Parks Ball Bearing Machine Company 1547 Knowlton St., Cincinnati, 0. Canadian Factory: 200 Notre Dame East, Montreal, Can, 1S] This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 23. FREE Greatest Catalog i | Bargains }.y %: ‘ ‘ Rs y Oc DIG ie Pay >> e id mame and address and we'll send FREE CATALOG. BUILD YOUR OWN RADIO SET All complete parts for the following sets consist of standard guaranteed parts and include drilled bakelite is and wiring diagrams for easy set construction. Ultra Audion Circuit . - . $ 8.95 Five Tube Licensed Neutrodyne 33.75 One Tube Cockaday ... . 10.45 Three Tube Cockaday . . ‘ Eight Tube Superheterodyne . ay One Tube Reinhartz ... Three Tube Reinhartz. . . Two Stage Amplifier Order from this ad and send ° one, Se not fully satisfied. FREE SERVICE DEPARTMENT Our radio ngineers will help — solve all your radio prob- a af x-yoR os informativun on set cons ration aid improve- HEADPHONES is service is free to “Randolph Special” 2200 Ohin oulied headset RANDOLPH RADIO CO i59.N. UNION AV, SCITMETOB CHICA The Home Worksho;] Tool Rack and Scraper Handje Made from Clothespins B* DRIVING headless clothesping into holes bored in a 34-in. board, itis possible to make a handy tool-rack fo, small tools. A clothespin also makes a good handle for a safety-razor blade. Whittle the ends to fit two small blocks, as shown, place the blade between the blocks, and clamp tightly with a machine screw and thumb- nut.—F. N. C. Cutting an Arched Opening (Continued from page 104) keeping the grain in the direction of the curve as much as possible. Nail the pieces into position under the head trimmer. “Fur” or strip the sides of the brace planks (if planks have been used) to the width of the studding and lath up, trim- ming the ends to conform to the curve, Then cross-lath around the curve and sides, and bend around the curve a strip of No. 18 gage, 1-in.-mesh chicken wire, or light metal lath, if available. Nail metal corners to the edges of the opening, plumbing them carefully and keeping them square with the wall. Cut out the old plate across the bottom of the open- ing. The arch is now ready for plastering. If it is desired to avoid the expense of plastering, cover the lath with plaster board made of wood fiber, so that a strip of it can be bent about the under side of the arch without breaking. In this event, the lath may need shimming out with thin strips so that the wallboard, whichis generally thinner than plaster, will be flush with the old plastered wall. The patching of the floor is the most difficult task of all. If the floor is hard wood, the neatest way to patch is to chisel or saw off the ends on each side of the opening, provided the boards run crosswise of the partition. This forms 4 rectangle, around which a strip may be mitered to form a border. Boards laid in the same direction as the floor fill in the remaining space. With a soft-wood floor, cut off the ends in the same way and fill in without @ border. Bevel the ends of the boards 80 that they will form very tight joints when driven down. Nail from the top with six- penny finishing nails. The arch and floor completed, replace the baseboards by mitering around the sides of the arch, and bring the picture molding to the edges, returning it upon itself, as shown. ; Paper the inside of the arch with 4 neutral color that will harmonize wit the paper in both rooms. ¢ ee SL Mg on it, bla toc ple an the ske

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hesping rd, it ig ack for handle he ends n, place d clamp thumb- ning n of the Jail the ie head 1e brace ) to the ip, trim- € curve, rve and > a strip en wire, >. Nail opening, keeping ; Out the he open- astering. cpense of 1 plaster it a strip or side of is event, out with which is will be I. the most r is hard ch is to h side of ards run ; forms 4 . may be ds laid in fill in the the ends yithout boards 80 nts when with six- i, replace ound the e picture y it upon h with & \ize with Ice Skates Easily F AN ordinary emery wheel is avail- I able, it is the work of only a few min- utes to make the wooden jig, or bracket shown, on which ice skates can be | damped for sharpening. Care should be taken that when the skate is clamped in position, as illus- trated, the center of the skate edge is af 7 [| ~/ S BLOCK RECESSED bg TOFIT SKATE Clamped on a wooden bracket, the skate is pressed lightly against the emery wheel on a level with the center of the wheel. The bracket, with the skate clamped on it, is slid along the top of the bench, the blade being pressed lightly against the grinding wheel. Don’t try to take off too much stock, but make several com- plete passes from point to heel of blade and back again. The smaller the diameter of wheel used, the more concave, of course, will be the skate edge.—F. S. Root, Fall River, Mass. Dutch Crafts Hall Chair (Continued from page 100) on the ends of it with beveled shoulders to correspond to the slant of C and D in the finished chair. Cut corresponding mor- tises in pieces C and D 5 in. from their top ends and fit the parts together. Key seats are cut near the ends of the tenons and the keys, H, 1% in. square and 2 in. long, are driven in. The cleats, F, 1 by 3% by 8 in., are bored for 114-in. screws, and beveled with the top ends of C and D so that all will fit flush against the bottom of the seat, A, to which they are screwed. Fig- ures C and D are 11)% in. apart at the top and 16 in. apart at the bottom. The braces, G, are 2 in. at the widest part. They are screwed to B and C with 10 round-headed screws, which vary in length from 34 to 114 in. Glue may be used in the joints, although screws alone will make a rigid chair and one that may be taken apart. Any standard stain may be used. The chair shown was colored with a dye made by mixing chrome green with gasoline and darkening it with lampblack. It was well tubbed and, when dry, finished with wax. A flat varnish also gives an appropriate finish on pieces of this character; glossy finishes should be avoided.—J. T. GARVER, nc Huntingdon, Tenn. POPULAR SCIENCE MONTHLY Insist on the Gold Seal HOMCHARGE. $18.50 at your dealer (in Canada $26). ALTERNATING CURRENT rte | | O Masses OO} FOR CHARGING ONLY ates 3 Wry 5 | A.C. WATTS 1100} MFD. & GUARANTEED BY THE AUTOMATIC You needn’t have “battery trouble” 14 Gold Seal HOMCHARGER Features 1—Simple; needs no care. 2—Efficient; costs about 5c to charge the average bat- tery, much less than bulb or liquid types of charger, 8—Quick; brings battery up to full charge overnight. 4—Tapers charge; cannot in- jure the battery. 5—Clean; no bulbs to break, no liquids to spill or pro- duce fumes. 6—Dependable; adjusted and sealed at factory. %—Lasts forever; only one moving part, the Tung- sten contact, which can be replaced at $1 after many thousands of hours of use. 8—Fool-proof; charges auto- matically, no matter which clip is attached to which battery terminal, 9—Safe; approved by Fire Insurance Underwriters. No danger of shock or fire. 10—Beautiful; sturdy metal case finished in mahog- any-red and gold. 11—Universal; made in types for all voltages of alter- nating and direct cur- rent. Charges all radio “A” and “B” batteries, and automobile batteries, 12—Quiet; its faint hum can- not be heard in next room. 13-—Unqualifiedly guaranteed. 14—Popular price—sold everywhere for $18.50; in Canada $26. Complete, no extras to buy, | @® This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. WO things will make your enjoy- ment of radio free from battery trouble. First, any good storage battery. Second, that excellent, simple, automatic charger—the new silent Gold Seal Homcharger. LE Hom Such a combination means minimum care and maximum results, with no trouble at all. Then you can use your set all you want. If the battery becomes weak right in the middle of a program, screw the Homcharger plug in any lamp-socket, snap two spring clips over the battery terminals, and go right on listening at full power. Leave the Homcharger connected overnight, and in the morning the battery is charged again. Everybody says this is the handsomest charger ever seen. The Gold Seal Homcharger is finished in mahogany-red and gold. It has rubber feet and so cannot mar polished floors, tables or cabinets. Safe—approved by the Fire Insurance Underwriters. Can’t injure anything. When buying a set, get storage battery tubes. They give most volume, and in many cases better results in distance too. Make sure the battery you buy is charged, then you can listen in for a week to a month before you buy your Gold Seal Homcharger. Price only $18.50 complete; $26 in Canada. Absolutely guaranteed. FREE! Ask your dealer or send direct for our interesting free booklet, “The Secret of Dis- tance and Volume in Radio,” containing valu- able information on this subject and fully de- scribing the GOLD SEAL HOMCHARGER. Insist on the Gold Seal Homcharger—ask your dealer. The AUTOMATIC ELECTRICAL DEVICES CO. Under the same management as the Kodel Mfg. Co. © 131 W. Third Street, Cincinnati, Ohio Largest Manufacturers of Vibrating Rectifiers in the World

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Quick Change Gear —9 Bend Only ena Complete Easy Payments If Desired This unusual offer comes to you from one of America’s largest exclusive builders of Screw Cutting Lathes, established 18 years. More than 31,000 of our Lathes in use. For example, in plants of 2 largest Steel Companies, in 8 largest Auto Factor- ies, in 5 largest Railroad Shops, in world’s largest Sew- Company, and by the U. S. Government, etc. From Small Bench Lathe to Largest Factory made in the last two years. showing pictures of all our Lathes. Note our liberal guarantee and 30-day trial offer. ing Machine Factory, in 2 largest Fire Arms Factories, by largest Oil Choice of 96 Styles /. You get our latest, finest Lathes, embodying 32 major improvements ou get our signed guarantee on every Lathe and 30-day trial! offer right in yourown shop. You take no risk. Write For FREE Catalog Compare our prices with what others ask. Send for Free Catalog today. South Benp LaTHe WorkKS, south Bena, ind, U.S.A. ture com- mutator Lathe 317 E. MADISON ST. POPULAR SCIENCE MONTHLY No extra charge for all equipment shown under lathe Under- Just a Few cutting mica on of the innu- an arma- merable jobs you can do with a lathe in your shop Making a conical die and punch Threading a tap rt, Ind “= oS consist sae sae fu in send “* hes on Sousa and other world-famous artists who | use and endorse Conn instruments as Supreme in Le oa Perfect in sca! Most reliable 4 action Easiest to play will help you choose the Conn which suits your talent, in the pages of this book. Free ; rial; — Payments. Send coupon for eralls. __C.G.CONN, Ltd., Elkhart, Ind. INSTRUMENTS WORLDS LARGEST MANUFACTURERS 12 Cells 24 Volts Solid Rubber Case 3SPECIAL INTRODUCTORY PRICE Sinaia Woekehop Biuepriall ture blueprints in the Home Worksho series are the simplest. difficult joints. Number 3 has the fewest parts. Num- ber 35 is perhaps the most elementary as it is little more difficult in construc- tion than a_ box. Numbers 37 and 39 are as simple in principle, but re- quire more time. Samuel Riker, 8rd, of Redbank, N. J., whose handi- work is illustrated at the right, says: End table with book trough I have made from your Blueprint No. 3. which I expect to make soon. as your directions are very clear and simple. illustrated on page 94. Make Furniture Building Fasy FREGINNERS ‘in woodwork frequently write the Editor asking which furnj. The easiest oneg are Nos. 3, 35, 37, and 39 in the list below, Their simplicity lies in the absence of This is a picture of a book trough end table that lal have the blueprint for a Priscilla sewing cabin I expect no trouble, This month’s blueprint, No. 39, is For a limited time only, and to introduce this new and superior Storage ‘‘B’” Radio Battery to the Public, we are selling it for $3.50. Regular ~ Retail Price is $5.50. Yousave $2.00 by ordering NOW. A finer battery cannot be built than the World Storage “B” Battery (iz og ee 24 VOLTS) To ten million homes with Radio Sets—and to lions of prospective buyers—this WORLD me tery brings a new co:.ception of battery economy and perform: ance. Hereisa battery that pays for itself ina few wee will last for years and can be a at a negligible Saat: And you save $2.00 by or A Superior Battery Equipped With Has heavy duty 21-8in. x Lin. x 1-4 in. plates and plenty of = circulation. Extra heavy glass jars allow ready observa- tion of charge and prevént leakage and seepage of current. It holds its charge while idle, at constant voltage. ou wil I find this battery a boon to long distance reception. It 8 away with a great semis noises so often blamed on **static '’ Mail your order today SEND NO MONEY Just state number of petreres wanted and we will ship day order is received. RA OFFER: 4 batteries in series (96 volts), $13.00, Pay Ramses after examining batteries. 5 rcent arscuant for, or cash In full with order. Send your order and save $ WORLD ) BATTERY COMPANY Makers of the famous World Radio **A’’ Storage Battery 1219 S. Wabash Ave., Dept. 80, Chicago, Ill. ntjoos mit- * Rat Complete List of Blueprints NY one of the blueprints listed below can be obtained from: POPULAR SCIENCE MONTHLY for 25. cents. The Editor will be glad to answer any specific questions rela- tive to tools, material, or equipment. Blueprint Service Dept. Popular Science Monthly 250 Fourth Avenue, New York GENTLEMEN: Send _me the blueprint, or blue- prints, I have underlined below, for WHICHUANCIOSE, 5... 0.0.5.0 6.610 005 cents: No. Title Price ae Sa re 25c 2. MORNE ANIC... 05. wes Cen 25c 3. Book Trough End Table......... 25c eS eae 6 SS re 25c 6. Two-Stage Radio Receiving Set. . .25c es tpt d 6) are 25c 9. Arbor with Gate and Seats....... 25c Oe SO Se re 25c 11. Bench and Tilt-Top Table........ 25c 12. Electric Washing Machine....... 25c BS, OED «aise cals sid accacet 25c 14. Toy Train, Horse, and House..... 25c 15. Home Workshop Bench.......... 25c 16. Inlaid Radio Cabinet............ 25c 17. Cedar and Mahogany Chest...... 25c 18. Telephone Table and Stool....... 25c 19. Grondtather’s Clock... «0.000008 25c Re Te Sh ee 25c 21. Colonial Writing Desk........... 25c 22. Girl’s Cabinet and Desk......... 25c SN a eee 25c¢ Po ae | Ss 25¢ 25. Sailing Outfit for Canoe.......... 25c 26. Baby’s Crib and Play Pen........ 25c 27. Kitchen Cabinet Work Table..... 25c 28. Pullman Play Table............. 25c 29. Toy Tea Cart, Garage, etc........ 25c 30. Tool Cabinet, Bench Hook, etc. . .25c 31. Priscilla Sewing Cabinets........ 25c 32. Chinese Game Table............ 25c 33. Pullman Dining Alcove.......... 25c 34. Trellises for House and Garden.. .25c 35. Simplified Radio Cabinet........ 25c 36. Rush-Bottom Arm-Chair........ 25c 37. Simplified Bookcase............: 25c SB. OPOCOTE PMDIE. 5 occ ccc cece eee 25c 39. Salem Chest of Drawers.......... 25c DENIES dis aousie nia eich lero 0.939 kde ns a: bie age Re (Please print) RPP eee eee eT ee Tee eT ST eT ST a ee er SAVE $2.00 BY ORDERING NOW: © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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vith igh dle that I also -abinet, trouble, 39, is — sted rom: r 25: 1 to rela- rent. 4 Home Workshop Chemistry . Simple Formulas that \ Will Save Time *, and Money VERHEATED machinery, engine O and motor bearings can be detect«d instantly if they are painted with a prepa- ration of silver mercuric iodide, which is a chemical most sensitive to temperature changes. This paint can be prepared in any home workshop. At ordinary temperatures silver mer- curic iodide is yellow, but it turns dark red when heated to 115° F., a temperature POPULAR SCIENCE MONTHLY @ O7] aera Preparing a heat-in- dicating compound much below the boiling point of water. In order to pre- pare this chemical, make three solu- tions. The first consists of 3.3 grams of potas- sium iodide in 25 ec. of water. The second is made by dissolving 1.8 grams of mercuric chloride in 25 ce. of water. The last is 1.7 grams MOHAWK CONSOLE Collecting the yellow precipitate When all three solutions have been | prepared, mix the first and the second | and shake thoroughly. Then, and not | before, add the last solution and stir. | Filter the solution, collect the yellow | precipitate, | and mix it with a thick gum solu- tion. Paint this on pa- per or on any sensi- tive bearing. It will show anyslight in- crease of temperature by its red color. Moisture is abstracted from other sub- stances by heat or, if heat cannot be ap- plied, by means of calcium chloride in a dish placed within a larger box containing the subszance to be freed from moisture. This substance avidly takes up all avail- able water, but the calcium chloride, in order to do this, must be in small lumps or granular in form. When the calcium chloride has lost its original shape in the Mixing the silver mercuric iodide with a gum solution box, it must be replaced by fresh. Oe of silver nitrate in 10 ec. of water. IS) 129 Put Away Your Headphone You Can Tune Across the Country with Loud Speaker Volume. § on Just ONE Dial Years ahead in perfected, simplified tuning and in loud speaker volume, the sensational new Mohawk is a leader among 5-tube coast to coast radio sets with its true ONE Dial Control. Every good feature of 5-tube power—long recognized as the most efficient—is now im- proved so that Selective Loud Speaker Distance Reception is now a definite, dependable ONE Dial Control that everyone can operate with ease. No Need for Headphones The new Mohawk is fundamentally and essentially con- ceived and constructed to be a loud speaker receiver. Without headphones the Mohawk’s ONE Dial will tune in stations all across the country direct on the loud speaker for everybody to hear. Even more delightful, the super- selectivity of this ONE Dial tuning goes far above the average. It will cut through the nearby stations with unfailing piecision and bring in the distant ones loud and clear. Children can do it—elderly people—any member of your family and friends. Never before has there been this freedom from the diffi- cult task of carefully adjusting several complex controls. And in your home Mohawk beauty of appearance will again increase the pleasure of its wonderful performance with just ONE Dial. Table model, console and consolette are each built in distinctive period type Adam Brown walnut cabinets. The console and consolette have built- in loud speaker, also battery compartments. Every model is broadly, fully guaranteed. e 5 Tube Receiver Send the coupon below. Find out the new facts which show the superiority of this 5-tube Mohawk set—and why you can now absolutely depend at all times on long range. beautiful clarity of tone and wonderful volume tuned direct on the loud speaker with just ONE Dial—and all at NO GREATER COST. Mail the coupon NOW. Mohawk Electric Corporation 2236 Diversey Blvd., Chicago, IIl. i Mohawk Electric Corporation, 2236 Diversey Blvd., { Chicago, Ill. I Send descriptive literature on the I { Mohawk ONE Dial Receiver. | | I l pe Pak EUS. 0.0.4.5. 6 sks 0a ere CURLS | = sine mention your local Radio i ealer’s Name. — ee eee Ser IS] This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. —te

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130 } ALI /._/ ¢, WARGEST RADIO STORE 1M Fates HN NEU ip s ‘4 acc latest Knock-Down Kits, Accessories. your FREE copy today! complete assortment of the best and N“ other Radio Catalog includes such a You need this book—write for Parts, and POPULAR SCIENCE MONTHLY ookups/ cAll the latest and best Hits’in our new An Unequalled **Kit’’ Service All parts for each “KIT” have been carefully selected and tested by our staff of graduate Radio Engineers — satisfactory results are guaranteed. Dealers! Jobbers! Manufacturers! ATTENTION! We will pay you spot cash for your surpius stocks—brand-new ap- paratus only! Write and tell us what you have. Completely drilled and engraved panel included with each “KIT.” Makes set building easy and sure. knowledge required to build your rad Save Money Our business is to buy up manufacturers’ an fully guaranteed, —but only brand-new, ; Our enormous buyi advertised apparatus. —even way below manvufacturer’s costs. T' our catalog is crammed with thousands of dio Bargains. . e_— On GUARANTEED APPARATUS ment surplus stocks, jobber and dealer bankrupt stocks permits us to pay spot cash and get rock-bottom prices No other concern gives this FREE service. Easy to understand Instruction Book and Blue- Prints included with each Outfit. No technical io set. d govern- nationally ng power hat’s why wonderful Remember our motto: Salvage means— SAVE, SERVICE, SATISFACTION $50 For Unusual Handicraft Photos iy YOU make a hobby of your home workshop, you may have built at some time or other a piece of furniture, a model, a toy, sporti equipment, scientific apparatus, or some sort of household utility that jg out of the ordinary—something that causes your friends to exclaim: “How did you ever manage to make that?” Such an article is the inlaid library table described below. Poputar ScrENcE Monruty wants photographs of the more uncommon and ingenious handwork of amateur craftsmen. For the best photographs received on or before Feb. 24, a first prize of $25, a second prize of $15, and a third prize of $10 will be given, Other photographs suitable for publica- tion will be purchased at regular rates, Each contestant should write a brief description to accompany the photograph—not more than 200 words—and tell how he came to make the article. In many instances it may be advisable to submit two photos, one an attractive picture showing the object in use and the other giving a close-up of its construction. The Board of Editors of Poputar Science Montuty will act as judges and their decision will be final. Un- available photographs will be sent back only when accompanied by a self-addressed label bearing return postage. The winners will an- nounced as soon as possible after the judges complete their task. BROS.& SEND F ae— Over 2,000 bargains 18-K Solid White 14-K Solid White Go tions. Gold fill ebines FATECS Aanon 3 le ins ‘3 . Delivered on first pay- 4. ment of $5.50, ther LOFTIS BROS. Dept. K871 -¥. Cas RAYMOND CO. fers OR CATALOG: Jewelry, Watches, ete. Sent pre- paid for your FREE Examination. Catalog explains everything. 1d, 1 Yi, High-Grade Railroad Watches juaral pecti HAMILTON No. 992, 21 Jewels, Adjusted to 6 Post. om iar aids SBS 1°22 a Week & CO. National Jewelers 108 N. State St., Chicago, fll. Stores in Leading Cities IS] This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. in Diamond-set GENUINE GOLD LEAF LETTERS Guaranteed to Never Tamnish Anyone can put them on stores and office windows. Enormous demand, large profits. Paul Clark says: Smallest day $28.70. R.L. Reel made $920 in two months. Write today for free sample and liberal LF offer to general agents. AGENTS rrorir METALLIC LETTER CO. _433-E_N. Clark, Chicago | 73. $29.75 id, 15 J. 333-25 DON’T. WEAR; A TRUSS | BE COMFORTABLE— Wear the Brooks. Appliance, the modern scientific invention which ves rupture sufferers immediate re= lef. It has no_ obnoxious springs or pads, Automatic Air Cushions bind gad draw together the — arts. osaives or plasters. Durable. Cheap. Sent on trial to prove its worth. Be~ @R- C. &. ameavans ware of imitations. Look for trade-mark bearing portrait and signature of C. E. Brooks which appears on every Appliance. None other genuine. Full information and booklet sent free in plain, sealed envelope. BROOKS APPLIANCE CO., 230-A State St., Marshall, Mich. 5022 Pieces of Wood Inlaid in Library Table Top ONE typical variety of wood from each state in the Union, as well as Alaska, Cuba, Hawaii, and the Philippines, is in- laid in the top of the unique library table illustrated below. It is the work of Gordon H. Turner, Professor of Physics and Chemistry at David Lipscomb Col lege, Nashville, Tenn. There are 5022 pieces of wood in the top. In fixing them in place, 888 holes Fen se tor a ay This table, built by Prof. G. H. Turner, of Nashville, Tenn.; contains 52 different woods were drilled and 444 dowels were used. The framework also is a monument painstaking intricacy, for 808 holes for dowels, screws, and other fastenings welt) (Continued on page 131) scr of the oil, c02 of in a will forv shor bolt

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given, vublica- ir rates, vrite a ny the n 200 -o make : it may photos, ning the iving a OPULAR ; judges 1. Un- oe ~«sent d by a return be an- le after sk. » laid in p from each as Alaska, ines, is in- yrary table . work of of Physics comb Col- ood in the 888 holes Turner, of ent woods were used. mnument of 8 holes for enings welt) _ 5022 Pieces in a (Continued from page 130) drilled or bored, and 148 dowels and 236 ws were used. The finish on the framework consists of nine coats of varnish and wax; over the inlays are four coats of boiled linseed oil, 12 coats of thin white shellac, six coats of clear oil varnish, and three coats of wax. Rubbing down this record- a Pa eae 8s € am i haiti tattle The table-top contains 5022 pieces of wood held together with 444 dowels and glue breaking number of coats was in itself a task extending over weeks. While reading poems on trees, Pro- fessor Turner got the idea of preserving in a table-top pieces of the most familiar trees of all sections of the country. In the selection and collection of the woods the Forestry Service of the United States Department of Agriculture, as well as state foresters, experiment stations, and conservation stations coédperated. Novel Skis Made Cheaply from Rain-Conductor Pipe Pp SCARDED galvanized _rain-con- ductor pipe, which can be picked up in almost any second-hand lumber yard, will make a novel pair of skis. Cut off two pieces 6 ft. long and, just forward of the center, make two slots, as shown, about 15 in. apart. Next, prepare two hardwood foot boards 6 by 18 in. with bolt holes 15 in. apart, as well as two h yee Hie SPuIT BOUT al The addition of a footboard turus & length of rain-conductor yipe into a practical ski slots 8 in. apart in the front end for tie straps of heavy tape or narrow leather. : Through the holes in the foot boards Insert T-head bolts made by sawing off the heads of stove bolts, splitting their shanks and bending the split sections out- ward. Put the heads through the slots in the pipes and turn them at right angles so that they will hold when the nuts are Screwed down tightly. A wide elbow plugged with wood is forced on the front of each pipe.—L. R. \ POPULAR SCIENCE MONTHLY Nats £2 Llictatennr YIevt Cases = rn, ment. acquisition of truth. formation.” progressive men of their day. & Research Bureau THIS BEAUTIFUL FRENCH STYLE BOOKCASE—FREE! Educational Reading Courses CH Education is the process of conquering one’s environ- The widening of this circle. ends only with life. Every day the world should be made new by some new Huxley says—‘‘All education is habit Those who form the Encyclopaedia habit— a few minutes a day with Nelson’s—are the educated and JOHN H. FINLEY, Editor-in-Chief. | a TOD Perpetual Loose-Leaf ENCYCLOPAEDIA for Special Information NATURE STUDY, AGRIC Nelson’s Reading and Study Courses in CIVICS AND LAW, CIVICS AND POLITICS, LAW AND PROCEDURE, UNITED STATES HISTORY, BUSINESS ECONOMICS, NOMICS, furnished to all subscribers, are declared by educa- tional authorities to be equal to a college course and training in each of these departments. Nelson’s Free Research Bureau ULTURE AND HOME ECO- Nelson’s is entitled to free membership doubt on any subject, old or new, write FOR SCIENTIFIC REPORTS AND SPECIAL INFCRMA- TION AND CORRESPONDENCE. Every purchaser of in this Bureau. If at any time you are in to this Bureau with the positive assurance that you will promptly receive the latest obtainable and most dependable information. THE GREAT AMERICAN ENCYCLOPAEDIA NELSON’S PERPETUAL LOOSE-LEAF ENCYCLOPAEDIA—the Great Ameri- can Reference Work—is published by one of the oldest and largest International Publishing Houses. The Editor-in-Chief is John H. Finley, LL.D., L.H.D., Editor, New York Times; the Canadian Editor is Sir Robert Falconer, K.C.M.G., D.Litt., LL.D., President of the University of Toronto; the European Editor is Sir Henry Newbolt. Its staff of contributors includes men and women foremost in Scientific, Professional and public life, who are themselves making history. This Great American Encyclopaedia of the world to the very latest activi- ties of the present day; by means of the Loose-Leaf binding device, it is the only Encyclopaedia always up to date—it cannot grow old—it is always dependable. Originators of the Loose-Leaf Reference System EXCHANGE Send for price list giv- ing amounts allowed for old Encyclopaedias to apply as part payment on a new Nelson’s Perpetual Loose-Leaf Encyclopaedia. is always an authority, in government departments, libraries, schools and educa- tional institutions everywhere. It covers every field of knowledge, from the beginning THOMAS NELSON & SONS Publishers for 125 year. Ss. F., 381 Fourth aecaiied New York City Dept. a Of | Wellington St., W., Toronto, Canada P. 77 Please send me your portfolio of sample pages, beautifully illustrated, containing color maps, plates | and photographs, and full information how, by easy monthly payments, I can own Nelson's Perpetual Loose-Leaf Encyclopaedia and receive FREE bookcase | and membership in Nelson's Research Service Bureau for Special Information. | whatever on my part. This must incur no obligation NGIMNG. coccccccccecccocceccccecocecnsecucecsosaceo | AGOTOEB..nccoc cccccccccacccecocesccscoceceseseesee | Gi ticicnncsccnnestesasamene ee Se fee 1 (Adv. Convrizht. 1925, Thomas Nelson & Son) IS] This seal on a radiv or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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132 POPULAR SCIENCE MONTHLY

How many products have you stuck to fortwelveyears? For considerably more than 4,000 con- secutive days, Mr. Fuchs, of Atlanta, has filled his pipe with the same kind of to- bacco and found satisfaction therein. Before he settled on Edgeworth, in 1912, this veteran smoker had “‘tried ’em all.”” And since then he undoubtedly has heard the praises of other good tobaccos sung by fellow smokers. But Mr. Fuchs stays sold—stays put. Because, he says, for a cool, pleasant, long smoke there is nothing to equal it. Other smokers who seek that kind of smoke should read his letter.

Larus & Bro. Co., Richmond, Va. Gentlemen: It has been my desire to write you for the past twelve years, ever since I have been smoking “Edgeworth.” I used every well known brand until I tried Edgeworth and have stayed in the ranks of Edgeworth smokers ever since. I have during that time mustered quite a number of recruits into the army of real pipe joy. Edgeworth is truly the aristocrat of smok- ing tobacco. For a cool, pleasant long smoke, there is nothing to equal Edge- worth. Wishing you further success, [ remain, ours very truly, Eugene A. Fuchs. For men like Mr. Fuchs we keep Edgeworth uniform year in and year out. That’s probably why the Edgeworth Club has so many life members. Let us send you free samples of Edgeworth so that you may put it to the pipe test. If you like the samples, you'll like Edgeworth wherever and when- ever you buy it, for it never changes in quality. Write your name and address to Larus & Brother Com- pany, 10B South 21st Street, Rich- mond, Va. Edgeworth is sold in various sizes to suit the needs and means of all purchasers. Both Edgeworth Plug Slice and Edgeworth Ready-Rubbed are packed in small, pocket-size packages, in handsome humi- dors holding a pound, and also in several handy in-between sizes. We'll be grateful for the name and ad- dress of your tobacco dealer, too, if you care to add them. To Retail Tobacco Merchants: If your jobber cannot supply you with Edgeworth, Larus & Brother Company will gladly send you prepaid by parcel post a one- or two-dozen carton of any size of Edge- worth Plug Slice or Edgeworth Ready- Rubbed for the same price you would

provides support for the near horizontal blocks before the top one, or key block, is in place. Build slowly. worry about shape or regularity. No Eskimo builds the same kind of figures on his upper blocks twice in his life. contour is the important point. Your key block may be square, oblong, triangular, or even round, depending on how you come out. place and lower it, if necessary, by the process of running your knife blade back and forth along its edges. An Eskimo starts his blubber lamp as soon as the igloo is finished. A lamp or an alcohol stove will do.

TAPE AND rag CORRECT. ~ CONTOUR a lamp that is really a pressure stove of small size, burning kerosene or gasoline. In five minutes they are seen to settle. If the temperature is around zero, they harden almost immediately. may form inside. shedding moisture or water when cooking begins; it also adds great strength. edges between blocks should be chinked with snow on the outside. door should be cut and fitted at the bot- tom in front. Unless a small ventilating hole is made in the roof, the air inside will soon be consumed and the stove go out. dow are built after about 20 minutes of the settling process. simply a small igloo outside the front door. footgear, and makes egress more pleasant. The sleeping platform is built up of hard

pay the jobber.

Building a nce Igloo (Continued from page 93) Fit carefully. Do not General Drop it gently into Explorers favor CUT HERE TO START SECOND WW

piste £ > JS A FITTING KEYSTONE,

~~" VESTIBULE Steps in building an igloo and sectional view showing the bed platform and the interior The object of heat is to ‘‘set’’ the walls. A fine glaze This is valuable in During this settling process the rough A half-round Vestibule, sleeping platform and win- The vestibule is It provides shelter for dogs and (Continued on page 133) To Each Purchaser | of a i A2-Volt"'B”* Stora e Batte y — with each rit ty ofa W One, ase oe for its guaranteed quality and joereiee. © by years of Successful Manufacture Satisfied Users. You save 50%. 22-Volt, 7 Plate wap "4 Pie 140 Amps. 16.00 Proves satisfactory Wor! this von ? ime end address — we ane ahip, bi battery day walter orn eived; and give you your choice of fandscme nickle Anish Auto Spotlite, FREE: Write tObayt w 2219 So. Wabash Ave. Dept. 7 ahle, es i Storage batteries. Te be sold retail for $6. 00. It is the only battery of its kind eauipped with solid rubber case—and {nsui offer NO (To those wh fer it, will REE handsome nickel finish Au to Spotlite, fistead 0 ofthe Bee 22 introduce

e Battery. The WORLD Battery | is is fe. Thewenanal Prices That Save and Satisfy Auto Batteries 6-Volt, 11 Plate $12.25 Radio Batteries 6-Volt, 13 Plate 24.25 §-Volts 100 Amps: i338 Shipment E: t to exami: 6 per cent nes. 2.2 thy - in full with or nation. 2-Yr. Guarantee Bond in Writing With Each ene Storage Battery id performance. Mail ORLD BATTERY COMPANY. CHICAGO, _ Batte: Can rechar; = oie Se will f Fast fadetnlst kent eakage. Take advantage of this remarkable aeaingt — Be sure to specify which is wan‘ nee

‘Stop Leaks! REPAIR BREAKS! MAKE Loose Parts Stay Ticur: Smooth-On No. 1 TOPS leaks and re- pairs breaks in pipes, furnaces, radiators, tanks, bursted water jackets, etc., with one simple application. Keeps bolts, nuts, grease cups, etc., from loosening and dropping off—makes loose handles tight—joins wood, metal or glass to each other tightly —holds on iron, brass, lead, aluminum, etc. For quick, cheap, lasting

© This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. joints and repairs and stop- ping many nuisances in every home, automobile and workshop, Smooth-On is in a Class by itself. Get Smooth-On No. 1in 6-02., 1-lb. or 5-lb. tins at any hardware store. SMOOTH-ON REPAIR SMOOTH-ON MFG. C0. BOOK Dept. 58 574 Communipaw Ave, Jersey City, N. J.

THIS ENGINE FREE | For AWhole Month SN TD) NON MONI SNA G Your request to trv this OTTAWA Engine is all we ask. Don’t send a penny engine $0 days. "The. make small monthly Sent direct Le foctesy.

n ‘es times before xp *resene oe Gasoline. Bizee 24. Bee E and up to FREE BOOK. <r. x vin Brom BE

sands use the OTTA Sars gy start 3a er,a AFTER TRIAL your name on Patt OTTAWA MEG. CO 1951-C King Street, Ottawa, Kansas *s Desk 1951-C Magee Bldg. ,Pittsburgh,® Enatoas < os ore

See page 33.

an pu

Page 101

s, etc., -makes , metal —holds C lasting id stop- ices in bile and Yn is in . lin . tins store. G. C0. POPULAR SCIENCE MONTHLY , kshop Quickly Built Box Makes Sled Comfortable for Baby OW a child’s H sled may be made into a useful eonveyance for the paby with very little work and al- most no expense, js shown in the accompanying il- lustrations. A few boards from a dry-goods box can be util- ized, or a %-in. board bought at the lum- ber yard. If the stock is 12 in. wide, it is possible to cut each of the four parts in a single piece. Otherwise, they must be made in two sections. A hardwood cleat is fastened to the back and front, and the box put together with screws and fixed to the sled with four small angle braces. Either paint or -3" >| BRACES | “ 1" FLAT Yex IRON ‘ ae — — iiiiaiaities | BACK FRONT Four wooden pieces, two cleats, and four braces are needed for the sled box varnish may be used in finishing the box. When the child outgrows this convey- ance, the sled is as good as ever for play purposes. Building a Snow I¢loo (Continued from page 132) snow blocks, dry grass or skins. It should be above the level of: the entrance to assure warmth. The window is a cake of fresh-water ice cut the size and shape of one of the front blocks and pushed in after the walls have hardened. A canvas or skin lining adds great lux- ury to an igloo. It should be made the shape of the finished house. Small pieces of tape lead from various points on its sur- face through the igloo’s walls to bone or wooden toggles outside. The ventilating hole at the top is kept plugged with grass unless the stove flickers or the walls melt too rapidly. I once lived comfortably through a 24-day blizzard in a snow igloo. Sat and played cards in my undershirt and smoked my pipe. Outside it was 52 below zero and an infernc of wind and drift. Inside was luxury. That’s why I think a snow igloo is a man-made miracle. A SPECIAL OFFER Made Only to the Friends of Poputar Science Monrary WaouLp it not be grand to have some good friend tell you how you could easily make $5.00—and by a little more work make many times $5.00? For You For Giving a little time to PopuLaR SCIENCE MonTHLY If you are one of the many readers of POPULAR SCIENCE MONTHLY who find this magazine in- teresting and useful, who feel that they could not do without it, then we know that you will be glad to tell a few friends that you like ‘“‘Popular Science” and that you want them to read it too. We have a plan we should like to tell you about, a plan by which we shall be glad to pay you Five Dollars, if you will undertake a few hours work for us. And if you can devote more than a few hours to our plan, you can make many times the first five dollars. Won’t you write your address on the coupon below and send it to us today? We will explain the plan to you by return mail. ==="SIGN THIS COUPON TODA Y=="" POPULAR SCIENCE MONTHLY, Feb. 2908 250 Fourth Ave., New York, N. Y. Gentlemen: Please tell me about your plan by which I can earn $5.00. Name Address... Occupation. L IS} This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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for Andrews —he knows!” “Seems to me that every time a tough problem comes up around here we always send for Andrews. “Send “Do you know why? It’s because he doesn’t. guess at a thing—he knows! He stud- ies those I. C. S. textbooks every chance he gets, and I want to tell you it has made him a valuable man for this firm. “This is the last time I’m going to ‘send for Andrews.’ For when he comes in today, he’s going to stay in. From now on he’s going to sit right in this office as my assistant. I wish I had more men like him.” Ho do you stand in your organization? Are you a guesser? Or do you know? Make up your mind, today, that you, too, are going to get the special training that you must have to get a better job and a larger salary. One hour a day, spent with the Inter- national Correspondence Schools, in the quiet of your own home, will prepare you for the position you want in the work you like best. Yes it will! Put it up to us to prove it. Without cost, without obligation, mark and mail this coupon and find out what the I. C. S. can do for you! Box 7636-D, Scranton, Penna. Without cost or obligation on my part, please tell me how I can qualify for the position or in the subject before which I have marked an X: BUSINESS TRAINING COURSES Business Management 0 Salesmanship Industrial Management OU Advertising yPersonnel Organization CL Better Letters Traffic Management (Show Card Lettering Business Law (J Stenography and Typing Banking and Banking Law LJ Business English Accountancy (including C.P,A.) (J Civil Service oOoOoooooonIoo Nicholson Cost Accounting Railway Mail Clerk Bookkeeping Common School Subjects Private eee, High School Subjects Spanish French Dlustrating TECHNICAL AND INDUSTRIAL COURSES Electrical Engineering Architect Electric Lighting Architects’ Blue Prints |Mechanical Engineer Contractor and Builder Mechanical Draftsman Architectural Draftsman Concrete Builder Structural Engineer Chemistry () Pharmacy Civil Engineer Automobile Work Surveying and Mapping Airplane Engines Metallurgy O Mining Agriculture and Poultry Steam Engineering () Badio Mathematics : i od ccdues nsnuiinenebibbeesbsbinecseos ues Street 3-6-24 SI cceusqnsauteusensepenteusseteerscrsanscccasnsouspeasevennsneoaetaseserenenseses ee Btate Oceunation Persons residing in Canada should send this coupon to the International. Correspondence School dian, Limited, Montreal, Canada POPULAR SCIENCE MONTHLY The Home Shipshape, £ : THE task of keep- Clothes-Line ie the ward lp Reel shape in appearance is made easier when | a strong, smoothly working, convenient _s reel is provided for the clothes-line. To make one, obtain the crankshaft and belt wheel of an old sewing-machine. Build a board drum just by nailing boards firmly together, with the crank- shaft between. Build up the reel to ample thickness and shave off the corners. Next, makea box to hold the drum, boring holes in each side to take the ends of the crankshaft. The wheel will have to be detached until the ends of the shaft are in place in the holes. Now put the wheel back on the shaft. The box must be firmly fastened to the side of a building or to a post. Drill a 5/16-in. hole through the outer rim of the wheel or have a smith do it for you, and A substantial reel with wooden brake put in an iron bolt to serve as a handle Cut off a piece of “two by four” aboy 8 in. long. Saw this at an angle of 45 degrees at one end and bolt the pieg through the side of the box as show so that it is at an angle of 45 degrees above the inside upper rim of the wheel, It will form a friction clutch. Close the front of the box except fora slit 14 in. wide across the entire front. Put a hinged cover on the top of the box. Fasten the end of the clothes-line to the drum with a lagscrew or heavy screweye and wind the line onto the drum. Pull the loose end through the slit and at- tach a ring. The drum of the reel illustrated holds from 200 to 300 ft. of rope. The line can be ad. justed in about five minutes. It is protected from dirt and wet and theyard looks better.— Miss, A. BESS CLARK, Maquoketa, Ia. A HEAT-RETAINING cover to be placed over flat-irons or dishes containing food may be made by fastening a wooden handle to an inverted pan, as shown. Asbestos gaskets are placed between the handle arch and pan, and it is advis- able to line the inside of the top with asbestos. This may be fastened on by using small rivets and large washers. A Heat-Retain- ing Cover Under this cover flat-irons heat up very rapidly on a gas or oil stove. It also is useful for warming over food in a frying- pan because it keeps the food moist and palat- able instead of dry and burnt on one side. —E. W. CorNELL, Adrian, Mich. For covering irons or a_ frying-pan METAL tubes in which so many toilet, medicinal, and artists’ preparations are sold, sometimes won’t unscrew. Light a match and hold the screw-cap over it. After a short time the screw usually will turn. : IN AN emergency M ending it is sometimes nec- Gas-Hose essary to repair a leaking gas-hose of the wire-wrapped variety often used on gas-stoves and mangles. Dip the leaking section of the hose in melted paraffin or candle grease until the coating on the rubber comes level with the wire winding. Then wrap the hose with rubber or friction tape. As a patched hose never should be used except as an emergency measure, replace it with a new hose as soon as possible. — HERBERT A. MINCHER, Youngstown, Ohio. WHEN a furnace is installed in an old house, it often hap pens there is a pipe from the kitchen range entering the same chimney. Many furnace men refuse to guarantee a fur- Improving Furnace Draft nace unless the upper flue is closed, for the reason that the furnace will not have sufficient draft. By cement- ing a small stove- pipe and elbowinto the chimney for the range connection, as is shown at the right, a good draft for both stove and furnace will be insured.—C. W. HUBERT, Corry, Pa. r1S} This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. giv ad an are he clo be: stu wo

Page 103

€ wheel, ept fora cross the Put a the top sten the S-line to lagscrew eye and mto the loose end and at- the reel Is from of rope. be ad- utes. It and wet *— Miss, dketa, Ia. nergency mes nec- repair a s-hose of used on e hose in until the | with the 108e with hould be measure, soon as VLINCHER, ‘urnace is n an old ften hap- is a pipe the same

n at the stove and

HUBERT,

—_——<—$—$

By USING a lead- Improving pencil and a grain- ing tool, the home Wide Flooring h worker can imitate narrow hardwood flooring on cheap, wide flooring boards. After being sandpapered and smoothed, the 4-, 5-, or 6-in. boards are measured and marked off into narrow divisions. Fairly heavy pencil marks are then made their entire down PENCIL MARKS fi ae by fi

length to imitate narrow joints. Then, when the varnish stain is ap- plied, the wood is grained by using a narrow graining roll in each divi- sion separately. This makes a vast difference in ap- pearance.

WIDE ELOORING

ns IN DECORATING our Stucco Ceiling | dining-room, _ the Finish stucco ceiling pre- sented a problem that we overcame in a manner others may find useful. The paper for the walls was to be a mottled brown. To suit this a bronze color was used in the ceiling finish, but the color could be varied to suit any toned paper desired. The ceiling first was brushed over with ahard varnish. This took off some of the loose particles and stuck on all the others, so that after the first coating nothing fell off. This was left to dry overnight and

bronze, that is, regular bronze powder mixed with bronzing liquid or ‘‘banana oil,” which dries very quickly. To tone down the bright color of the bronze, the next coat was a paint made of equal parts of linseed oil, turpentine and gasoline, with enough Prussian blue to give a light color. More blue then was added to make the color much darker, and the ceiling was stippled, that is, an area about 1 ft. in diameter was painted here and there on the ceiling until a clouded effect was obtained. This gave a beautiful finish and did not destroy the stucco effect, which so many finishes would have done.—H. C.

WHEN a docr-knob remains loose for Door Spindle some time, the set- screw threads in the Square spindle are apt to become so badly worn as to be worthless.- Instead of retapping the spindle and fitting a Screw for

larger machine ‘BRASS WOOD screw, simply turn a_ round- headed brass wood screw of suitable size into the old hole. The iron will-cut threads in the brass and bind the screw so that it will not work : loose. This isa repair always quickly made. SCREW \ Replacing a lost door-knob screw

then the whole ceiling was coated with

© This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. POPULAR SCIENCE MONTHLY | For Circuit Supremacy — Cir-KIT and Supereflex

Erla Supereflex—new epoch in circuits. Not just a“ wave” of popularity, but the permanence of basically superior principles, just as advanced today as when Erla introduced the circuits still rated more powerful, tube for tube. Expressing the best of Erla science, Supereflex circuits also are so easy to own! Not only because of extreme economy in first cost and operation, but also because Erla CIR-KIT enables any experimenter to produce these greater circuits flawlessly. CIR-KIT provides every need- ed item of Erla Precision Radio Apparatus—exclusively responsible for extreme Erla range, volume, clarity, sensitiveness and remarkable ease of control. CIR-KIT also provides full-size blueprints; stenciled base- board; and drilled, lettered panel, so that every step must be correct. Assuring lasting supremacy in circuits; the e) pride of a truly professional hook-up; and incomparable entertainment, C/R-KIT is outstanding in radio today. [] Electrical Research Laboratories Dept. S, 2500 Cottage Grove Ave., CHICAGO ER LA Erla complete radio instruments lift radio to the realm of art, with the same superiorities CIR-KIT brings. Erla Erla Table Cabinet Erla

a io

Console

U SEND NO MONEY J ee rinters’ wages are now so high you can 2 Genuine Diamonds 4/ 100 Each make big money in spare time Cut Stones, No Chips with one of our printing outfits, Solid Gold “~% No experience necessary. ur 4 instruction book makes every- thing easy. Presses $12 up. Pay for themselves in a short time, Write today for catalog presses, type, ink, paper, cards etc, THE PRESS COX 33 Meriden, Conn. #8150 $300 PROFIT Every Month from Battery Charging

PRINTING | offers Big PROFITS

ae, Terms if desired (6 mos. to Pay ) 14 kt. White Gold Top. Gold Emblem (any Lodge) or any Initial (Old English) Inlaid in Genuine HOPE RUBY Aisa, in Black Onyx end size of finger Trig <i Reg. Trade Mark Fey sig — guacomnens you éenuine diamonds, Send for Free Catabg JD Ff C fA SW , Buffalo Jewelry Mfg. Co., “The Mail Order House™ Dept. A Brisbane 6 Buffalo, N. Y.

No. 6132 Brings trade, beats competition. Only $35 cash brings complete equip- ment for 8 hour battery charging. Small monthly payments. Free trial on moneyback guarantee. Write for Free Bulletin 25. Hobart Bros. Co., Box P 2, Troy, Ohio.

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Rounded END fits your hand 27H 1 Coarse-cut on one side; fine cut on Picture is only 3/5 actual size) The name PLUMB insures long, faithful service is part of file. Gives control to stroke SHEATH comes with every file toprotect teeth Right now you need a Plumb All - Work’ File (*Trade Mark Reg. U. S. Pat. Off.) For sharpening tools, knives, etc.; for radio work; for filing steel, iron, copper, fibre, hard rubber, wood,etc., get a Plumb All- 3 b¢ At yout ° aie Work File. or by mail. : . (40c West of Files anything, | Rocky Mts.) Get itat any mee. sharpens every- | fora mechanics thing. Two files vit ‘your Gocier has anda handle, all in | tcss}teurGismrs one, with sheath iWon “We come to you e ’ next mail. to protect teeth. Carry it in your pocket, your tool kit, or car. You’ll wonder how you ever did without it. FAYETTE R. PLUMB, Inc. ® 4814 James Street Philadelphia PLUMB DOUBLE LIFE Hammers Hatchets Files Sledges Axes POPULAR SCIENCE MONTHLY HE foundry was about to pour a 10-ton casting. The furnace was up to heat with 14 tons of molten steel. The mold was complete to the final detail. Two weeks of exacting preparatory work had made all ready for the pour. As a last precaution, the molder tried out the release before filling the crucible. He - dis- ticularly maye to , — THN TnHeLHatat BEI tools that en connec- eu | 1] Ni al ‘Al if on boring tion. =) | mea | fl ae vl myn " , bars; tool After a ae i : i | | clearances in tense and sbi yw work on anxious es . b y machines, scrutiny of ae \/; “| on lathe the break, Mn 4 tools, and in the master ip work being molder gave ay assembled. a few quiet Scratch orders. A brushing machinist and buffing brought in a to remove portable forging or electric drill, casting scale some drills, and in as- “on several In critical emergencies, as when this crucible connection broke, sem bl] y olts. ; an electric hand drill often can be used to save the day work, before Ten min- enameling utes’ work by the mechanic and his helper with the drill and they were able to put bolts through to hold the connec- tion. The foundry work then proceeded to a successful pouring of the huge casting. Not only does the portable hand electric drill come to the aid in breathless emer- gencies like this in a big foundry, but the usefulness of the tool follows through to the final installation of the identification plate on the finished construction. The hand drill of the electric type, with grips, convenient switch and ad- justable chuck, is a comparatively late utility. It really has come into almost universal applica- tion and been appre- ciated thoroughly during the past 10 years. Its moderate cost, convenience, and serviceability are responsible for its popularity. The tool is espe- cially convenient be- cause it obtains its power from any elec- tric-light socket. The light weight and portability adapt it to manual use in practically every location, no matter how inac- cessible. Jobs ranging from factory pro- duction to the household task of sharpen- ing the carving knife, find the portable electric drill an indispensable time- and mi Wiriely SAW --= EMERY CONE-’ What Save flan hs es Portable Electric Drill By George Arthur Luers Mechanical and Automotive Engineer Using an electric drill to drive a lathe, a saw and a screwdriver, and for other purposes with the Aid of a labor-saving tool. To describe the applica. tions of an electric drill at length would be impossible in this article, but a brief outline of the valuable work that can be accomplished by it in several different fields will suggest what ao can do in your own line with a good rill. In the Machine Shop—Grinding, par. or polishing the finished product. Drilling holes at assembly for bolts, rivets, screws, and for attaching name plates. Countersinking and _ reaming during assembly. Screwing on nuts is another use for the drill, when special fittings are available. These fittings are some simple form of friction clutch, made up as a plate clutch, which will release the drill from the work when the bolt seats or the tool jams. A clutch also is required in many instances for tapping or reaming, where it is not practical to govern the tool movement closely enough by the switch alone. A variety of other work in which a re volving tool is used, can be accomplished almost as easily as drilling. In Carpentry and Pattern Shops— Boring with the bits intended for the brace is an achieve- ment in which the portable drill vastly exceeds all the speed of hand work. Dowel holes, door- latch mortises, tum- bler-lock recesses, and almost every form of circular opening can be made with the electric drill without physical effort. Tool sharpening, by means of a small (Continued on page 137) —— © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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f a al. To »plica- lectric in this luable r it in ; What 4 ood z, par- larly that place boring tool neces in k on Lines, lathe and in being bled. ratch shing buffing remove ig or ig scale in as- rbly , before neling ' bolts, r name eaming for the ‘ailable. form of clutch, ae work ims. A stances ; is not yvement ie. of other ch a re is used, aplished asily as try and hops— the bits or the achieve- 1ich the ll vastly he speed k. es, door- es, tum- recesses, 5 every circular electric f a small POPULAR SCIENCE MONTHLY Better Shop Methods A Portable Electric Drill (Continued from page 136) emery or carborundum stone mounted on the drill, is most expeditious. The sharpening of circular saws, blades of trimmers, Planer blades, router blades, and various other machine tools can be taken care of, frequently by grinding them in place. "e Grinding gouges of the inside ground type, is done readily by using an emery cone held in the drill chuck. Driving screws can be accomplished with great speed and ease with the port- able drill. A disk clutch that will release when the screw “‘bottoms” is required in this application. Sawing, such as is necessary to cut through centers of flooring or walls, can be done with a small circular saw chucked in the drill. Electric outlets, water pip- ing, and heating-pipe installations re- BRISTLE BRUSH n am! 4 ie) Hint FIDRILL HAMOIS OR CHEESECLOTH POLISHER TAPPING, as Le" SETTING UP NUTS FRICTION CLUTCH In auto maintenance "work, the electric drill has many uses other than drilling quire the use of the keyhole saw, but the small circular saw on the drill dispenses with much laborious keyhole saw work. Many other applications of the drill in pattern work are possible by making simple revolving tools to replace edge cutters. By use of a pulley, the drill can be made to drive a foot-power turning lathe. The writer has seen the drill adapted by use of a crank attachment for driving the sand riddle in a foundry. In the Building Trades — Drilling through girders, joists, and beams makes the portable drill an invaluable aid to the builder. Many operations in plumbing, electric work, heating-plant work, gas- line installations and roof work can be done faster with its aid. Seratch brush work, in which a wire brush is mounted in the drill, makes pos- sible a much desired finish for face brick on the building front. With smaller brushes the routing of mortar from face brick can be accomplished with ease and rapidity. Emery and sandpaper disks mounted in the drill are used to advantage in fin- ishing inside trim. A circular saw on the drill finds a multiplicity of uses in the building, from hanging window sashes to cutting special moldings for trimming out. An emery wheel on the drill allows edge tools, from the chisel to the hatchet, to be (Continued on page 138) Easy to Tune— Easy to Own! f HE new Paragon line of Radio \ = Receivers is making radio history for fans of all ages and purses—the new Paragon Four, especially. A four-tube set that is getting every- thing that’s in the air. Getting it clear and strong on the speaker. And tuning in sharply and distinctly at a twist of the single tuning dial. As fine a set as Paragon ever made— Three, doing all that you expect of far cost- $48.50 lier sets that use more tubes—yet costing only $65. No greater value Three tubes. Ma- in radio today! hogany case 17 inches rv 7 5 ‘ long. Clear speaker Write for “Station Please!”’, a folder reception over range picturing and describing the new set that amazes you. in detail. r, $65 Four tubes. Handsome mahogany case 21 inches long. New Paradyne non-radiating circuit. Almost unlimited range for clear. strong speaker reception. New Paragon Fou New Paragon New Paragon Two, $97.50 Two tubes. Mahogany finish case, 11 inches long. Excel- lent speaker tone and volume from local stations. Almost unlimited phone range. ADAMS MORGAN (CO., Inc., 2 Alvin Ave., Upper Montclair, N. J. Originators since 1915 of Record-holding Radio Receivers See top page 10 in front of book for details $25.00 in PRIZE The Saw Sold on Money-Back Guarantee Backed by a guarantee of satisfaction we have built the largest business in small bench machines in the World. BOICE-CRANE JUNIOR SAW This sturdy precision built machine will saw, sand, miter, rabbet, tenon, and many other operations wich ease and accuracy. Saws 14%” , stock. Driven by % or 4h. p. A motor attached to any light socket. | Write for Descriptive Cata- \ log on Bench Machines, Jointers and Band Saws. W. B. & J. E. BOICE Dept. P.S. 2 A, Toledo, Ohio **Largest Makers of Small Bench Machines in the World *” F(S] This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33,

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SoSp vim atv POPULAR SCIENCE MONTHLY WhentWinte Winds BlowCold A 5-tube Tuned Radio Frequency Set made of the finest low loss materials and in a beautiful genuine solid mahogany cabinet, that is attractive enough for the most pre- tentious room, and at sixty dollars, eco- nomical enough for the most modest. Combines all points essential to the perfect receiver. Real distance reception without that squealing and howling. So_ selective that once a station is picked up—it can be brought in again on the same points on the dials, whenever you want it. And, what’s more, sub-panel. Users Claim It Is the Greatest Value Ever Offered in a Radio Receiving Set ! It’s Easy to Build a five tube radio frequency re- ceiver when you use the Freshman Masterpiece Kit. The result will be a receiver that will bring in even the most distant stations with the volume and clarity of locals. The equal of any 5 tube set in selectivity. simplicity of ope I- ation and all around e ciency. No Neutralizing or Balancing Condensers Required IT IS MIGHTY EASY TO OPERATE © Have Your Dealer Install One in Your Home! All genuine Freshman Masterpiece Sets have a serial number and trade-mark riveted on the The Receiver is not guaranteed if number has been removed or tampered with. CHAS. FRESHMAN Co., Inc. FRESHMAN BUILDING 240-248 W. 40th St., New York Have You AN INVENTION? If;so the WORLD PROGRESS will show you how to Protect and Profit From Your Ideas Sample copy free. One year’s subscription 40c. nd for free book, “WHAT TO INVENT” containing Suggestions to Inventors as to Inventions Needed. We invite manufacturers to address us regarding inventions they want. WORLD PROGRESS PUB. CO., INC. Room 202 Victor Bidg. Washington, D.C. BLANK CARTRIDGE PISTOL tection against Burglars, Tramps, & Dogs PR ICES Well made and ef- * fective; modelled on latest type of Revolver; appearance alune is enough to scarea burglar. When loaded it may be as y effective as a real revol- ver without danger to life. It takes standard .22 Le) =A Ry Cartridges obtainable everywhere. ic. a. quality $1.00 Postnals: t 4 - Blank Cartri by express, 50c 10 toe " Johnson Smith & Co., Dept. ?°288, "Racine, Wis. Containinz a full line of complete outfits and parts at exceptionally low prices. rite immediately to 1346 S.=Michigan.Av LU DE N Sana. © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. A ashictshi caps Drill (Continued from page 137) kept in condition on the spot without loss of time. In the Tinsmith and Forge Shop— Drilling and cutting out circular disks jy thin sheet metal is one useful job that can be accomplished by the drill in the | sheet-metal shop. Tool sharpening is done as in previous | instances, with an emery wheel mounted | in the drill. The scratch brush and polishing wheel are nearly indispensable, and the sheet- metal worker will find the portable to | have advantages not met with in the fixed | grinding head. The scratch brush makes possible clean and perfectly soldered joints. The countersinking of forged parts and drilling for rivets can be done in the forge shop many times faster than with the older type of hand drill. The portable has a variety of uses in the tin shop and forge shop that extend from grinding the shear blades to resur- facing the face of the anvil. Many special uses require only special chuck fittings. In fact, in an emergency it will do numer- ous odd jobs, from stirring the mixing vat to driving a ventilating fan. In Private and Public Garages—In the repair and maintenance of automobiles, the hand electric drill comes in for a variety of work that perhaps is not ex- ceeded by any other tool. Hole drilling with the portable expe- dites the application ‘of riveted patches to the body and fenders. Special fittings for the dash, luggage carriers, speedom- eters, electric wiring and lights are all in- stalled with the aid of a portable. Wire scratch brushes, driven by the drill, are used to rasp and buff the rubber on tubes and tires for repairing in some of the large service stations. Reboring cylinders and honing cylin- ders is work for which special tool equip- ment, using the power of the drill, is marketed by several manufacturers. Nut drivers, screwdrivers, and valve grinders are also being made by manv- facturers for use with the portable. Carbon removal with the wire scratch brush in the portable is an improvement over scraper methods. The wire brush removes every vestige of carbon, even from recesses in the cylinder head, as well as the deposits around the valve ports. Canvas buffing wheels, dry or with ap- plications of rouge or crocus, are used to clean up the brass, nickeled and alu- minum parts of the car. Very soft wheels, about 6 in. in diameter, should be used on the nickeled parts. Wheel cleaning is done expeditiously by mounting a round bristle brush in the portable chuck. A polishing brush can be made from chamois or cheese-cloth, mounted in a wooden holder and secured in the port- able chuck, for use in polishing the waxed surface of the car. These are only a few of the uses. The portable is an invaluable aid in every de tail of work from drilling for a cotter pin to plugging up a cracked cylinder head. (Continued on page 139) Carwin a c s Si me cue eo — oO Me wrt QoQ 2a @® emte Gate oh at lUuelCUlCUC CD eS — =e le

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’ whee] sheet- ble to e fixed makes dered Parts In the n with uses in extend resur- special ittings. numer- mixing -In the .0biles, for a not ex- > expe- patches fittings eedom- all in- by the rubber n some - eylin- equip- lrill, is S. | valve manu- scratch vement » brush 1, even as well ports. ith ap- used to d_ alu- wheels, e used tiously . in the e from d ina 2 port- waxed . The ery de- ter pin ead. February, 1925 ee i ; FIGS Better Shop Meth Cutter Grinding Arbor CUTTER 2-Y4'SCREWS rot ™ GRIND DIA HERE (MACHIN HIS arbor is designed for grinding the outside diameter on removable drill and reamer cutters. The cutter is held on the arbor with two fillister-head screws in the same position in relation to the center as it is when in place in the drill or reamer body. A Portable Electric Drill (Continued from page 138) In the Home Workshop—In the home workshop, the portable drill finds an unlimited field of usefulness. Repairs of every nature, from the furnace to the in- stallation of complete window and door screening, are accomplished neatly and rapidly with a handy portable. A practical application of the drill is as a small power plant to turn the home- workshop lathe. A pulley and clamp connect the portable with a belt drive to the lathe headstock spindle. The scratch brush, grinding wheel, and buffing wheel are always useful attach- ments to the home-workshop drill. Tool grinding, metal polishing, removal of old paint and enamel are done with these attachments. The buffing wheel is of service for many jobs, from refinishing a chandelier to refinishing a brass bed. With the addition of a small circular saw and a guide plate around the saw, the portable may be converted to wood cut- ting. Many constructions are possible that will utilize the power of the drill. These are along similar lines to corresponding shop machines. Surface grinders, small milling attachments, stationary drilling machines, and holders for the portable drill can be made from iron plate, angle iron, and other easily handled materials, including wood. Care of the Electric Drilli—The drill requires care. It should never be water soaked and shorted. It is advisable to keep it in a box on a shop shelf, shielded from dust and dampness. The electric cable connection should be given an occasional coating of shellac varnish. The cable should not be kinked unneces- sarily, or pulled or rubbed. The commu- tator and brushes should be cleaned occa- sionally with fine sandpaper. Oil the bearings with the regularity prescribed by the maker. It is not neces- sary to take the machine apart fre- quently, but all the screws and bolts in the frame should be kept intact and tight. The electric drill represents the modern trend in tool design. It is no wonder it increases in popularity every day, be- cause it has an unlimited capacity to save time and labor. — POPULAR SCIENCE MONTHLY 139 eS TESTS SHOW FORD CAN RUN 60 MILES ON A GALLON The amazing fact that a Ford can run 60 miles on 1 gallon of gasoline was recently brought to light through tests conducted by America’s foremost engineers, where it was shown that a gallon of gasoline contains sufficient heat units which if properly atomized and mixed with air would give this additional mileage. Great strides have already been made in this direction by the recent invention of a simple attachment which can be installed in a few minutes without any alterations to the motor. It is common for Ford Owners to make from 40 to 44 miles per gallon after this marvelous device is attached. MOST WONDERFUL INVENTION TODAY BRINGS JOY TO FORD OWNERS Starts Ford Instantly Eliminates Oil Pumping in Starting a Ford Car in cold or zero weather is some- Front Cylinder thing every Ford Owner dreads—everybody realizes P > that difficult starting is an abuse on the starter and What a wonderful relief to Mr. Ford Owner when he battery. Thousands of Ford Cars are ‘‘laid up” realizes that he can run his car without the motor during the Winter just for these reasons. This great pumping oil in the front cylinder. Sounds like an difficulty has been overcome. ‘“‘The SUPER awful lot to expect of any device, but that is what the positively starts a Ford Car instantly in the coldest SUPER does and this is only one of its many advan- tages because it puts real efficiency into any Ford Car, weather.” Marvelous Device Complete Combustion The SUPER is so designed that it takes The SUPER is no trick affair—requires no mechanical adjustments and contains advantage of the present Ford Carbure- all the scientific principles of carburetors tor and properly atomizes the light as" costing $20 to $35 and in its natural well as the heavy elements of the fuel, action uses up every particle of unused converting every atom of gasoline and gasoline and breaks it up into a perfect kerosene into power preventing liquid vapor. The hitherto impossible is now fuel from passing into the cylinders, thus avoiding carbon formation and oil dilution, realized by the SUPER. Everybody Satisfied Easy to Sell Sells Like Hot Cakes Saves 3 to 7 Dollars Per Month This is a recent letter from one of our distribu- The best estm: . ; Ss PER is — yd , oe mate Ps tors: ‘‘Enclosed find draft for 200 more SU- dollars eacl th. besides tti if PERS, rush as I need them badly. I sold and into my motor. A. H. WORRA, fowa, banked $104.00 in one day. Hope to sell 1000 SUPERS next month. Makes 44 Miles Per Gallon The Bs, SR, Pe I have tried the SUPER and the results of the Making Big Profits Every Noon experiment are satisfactory. One quart of Heart 8 ig gasoline run my Ford 11 miles over improved roads which is just about again as far as I could run with the plain Ford Carburetor. G. E. YODER, Penn. Finds That Our Claims Are Correct I have been working the SUPER at noon only. of the Yesterday noon I made more money with the Motor SUPER than I did at my 11 hours’ hard work in the factory all day. J. L. LEHNER, Wis. Had No Previous Selling Experience I find that your claims for increased mileage are This letter shows what ambition does: _ ‘‘I sold six correct and that a big saving is made by your SUPERS in less than 2 hours tonight. I thinkit’sa SUPER, in fact, the best device I have met with in pretty good start—for it’s the first thing I ever that line, M. J. VAN LEEUWEN, Mass. sold.”’ E. MANGOLD, Ind. $60.00 TO $150.00 PER WEEK EASY You just can’t help making Big Money selling the SUPER because a trial sells itself and soon every one in the neighborhood get talking about this marvelous device. Men like Leonard, Shaw, Manner, Kinsley, Peters, Sands, Beck and Hall are not exceptional salesmen but just the type of men that saw an opportunity and were quick to grasp it when within reach. No previous selling experience is necessary, just a ‘little ambition on your part to make money is all we ask and we will extend the same opportunity to you. Spare time will pay you well. If you can devote your entire time so much the better, because the SUPER is a whirl-wind seller and takes hold in a locality like wildfire. " - ay x Men Wanted Everywhere To Introduce ~ We want distributors in all parts of the country to take ordersand deliver the £ e SUPER and to look after the repeat business that is bound to follow and to s ¥ such distributors we are willing to assign territory. You do not have to we OS “ own a Ford to take up this proposition but if you have a Ford it is easier to explain its many advantages. However a Trial of the SUPER convinces the most doubtful person and tells a wonderful story. A REAL FUTURE HERE 3% WEEKS SUPER CARBURETOR CQ., 2304°750 Fond Du Lac Avenue, MILWAUKEE, WIS. GR KE St a Oe ORI ost 0 PISS LW Hw 6 oe os DeForest -® poneycoms coms The Universal all-wave inductance. Back and front panel mountings. Send 25c for_ Super Het., R. F. and Honey- comb Coil Circuits and Complete Catalog. Chas. A. Branston, Inc. Dept. 9, 815 Main St. Buffalo, N. Y. i= i Hampton made $7 65 in four hours TIME spare time just wearing this Beauti- ful Hand-Tailored Cap, made to his Individual Measure, and you can do the same—you can easily earn $50— $75 a week in your spare time. Get This Cap FREE I want to give you this cap FREE—I know your friends will be delighted with its Class, Style and Fitand you will make a generous profit taking their orders, Choice of 5 styles and 25 fine fabrics. Send your name right away and I’!1 tell you how te make 60a week in your spare time. Write me at once. J. W. Taylor, st Protect your tools from theft. Write any name, engrave any design on tools and metal with electricity like writing on paper with pen or pencil. omplete outfit $3.50, prepaid anywhere. Interest- ing descriptive circulars free. Write to-day. Agents wanted. © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. Arkograt Pen Co., 1171-A East Stark St.,Portiand, Oregon Pres., Taylor Cap Manufacturers, Dept.9-B Cinci oO.

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POPULAR SCIENCE MONTHLY T makes all the difference in the world with the enjoyment you get out of radio whether the high notes of voice and orchestra are in tune or just a little ‘“‘off.’”’ ' A big point of the Bristol Audio- phone is that each instrument, and each vocal note, comes in in proper pitch. You will love your’ Audiophone for its pure harmony of reception. There are four Bristol Audiophones, priced from $12.50 to $25.00, and a cabinet model at $30.00. If not at your dealer’s, write for Bulletins Nos. 3011, 3017, and 3022-CA. The Bristol Company Waterbury, Conn. Pi OL AunisPnone © Gach Instrument of the Orchestra in PERFECT TUNE Mode! S $25.00 Solid rubber horn 1444” in diame- ter. Cast metal throat. Mottled bronze and gold on a velvet mat finish, LOUD SPEAKER Don’t Blame Your Set! If the batteries run down, you’re lucky to get anything but “sounds.” APCO Battery Charger keeps radio batteries alive. | Works noiselessly, efficiently, surely, fully charging any radio battery over-night for a few cents. 714 ampere capacity. Pays for itself in six months. Guaranteed one year. Write for circular and dealer’s name APCO MFG. CO. Baker Street, Providence, R. I. APCO PALES , for “A”? and “B’’ Batteries [ AHLBERG}- MADISON, WIS. e o For Perfect Conductivity 4 °* It is now possible for the in Radio amateur to get tight, clean joints in his home soldering that make the per- fect conductive path necessary in radio work. Mr. E. D. Fahlberg, former Professor of Metallography at Wisconsin University and Metallurgical Engineer with Western Electric Co., has developed Reddy Hot, the complete home soldering furnace. Heats iron in two minutes — non-explosive — Burns denatured alcohol. Reddy HOT Soldering Furnace and Tested Supplies Reddy Hot Soldering Outfit consists of: Large ideri er, detachable handle—Fine soldering canar eee Flo Household Solder—Can Reddy Stik non-corrosive Soldering Flux for Radio—Can Reddy Prest Sal Ammoniac, keeps tip clean—Can Reddy Rub Abrasive Tape. Complete directions. E Ask your dealer. If not obtainable we will send di- rect, for a short time only, on receipt of price. E. D. Fahlberg Mfg. Co., Madison, Wisconsin PRICE, JOBBERS AND DEALERS: Write or wire for attractive Reddy Hot proposition and samples. Display carton of 12. See eetee mans -——-_ E. D. FAHLBERG MFG. CO., Madison, Wisconsin Send me prepaid one Reddy Hot Soldering Fur- nace for which I enclose $1.50. P.S.M. My dealer’s name is Febru ary, 1925 i Success in Grindi (Continued from page 98) ng test, and much valuable data are com. piled for the information and guidance of the men who use their product. They are always ready and willing to help solve any of your grinding problems. Never condemn a wheel because it does not produce the desired results, before making sure that you are using the right wheel. Many times a man complains about a wheel when a change of grade would have turned the trick. Grinding wheels may be divided roughly into two classes or grades—hard and soft. These two grades, however, are subdivided into many degrees of hardness and softness. The grade of the wheel refers also to the strength of the bond that holds the grit in place. The hardness or softness of a wheel should not be confused with the hardness or softness of the grit. If a wheel is soft, it will wear away rapidly under working conditions, or the grit can be cut away very easily with a diamond when truing up the wheel. A hard wheel is not affected so easily. The cutting efficiency of a wheel de- pends upon the fineness or coarseness of the grit. The grit or grain is known bya number, which signifies the size of the abrasive particles that will pass through a screen of a given number of meshes to the inch. In other words, a 40-grain wheel means that the grit of the wheel will pass through a screen having 40 meshes to the inch. T° SELECT the right wheel for a given job, you must consider the kind of metal to,be ground, whether it is hard or soft; the size of the job, how much metal is to be removed, and the finish desired. If the wheel should be too soft, the bond will be too weak to resist the cutting action for any length of time and it will wear away before the abrasive has had time to do its work. On the other hand, if it should be too hard, the bond will hold the grit long after it has done its work, the wheel will clog up and become glazed, and it will not cut. Con- tinued use in this condition will cause burning of the work or excessive heat. Hard materials require soft wheels and soft materials require hard wheels. One other factor governs the action of a wheel, that is, the size or diameter of the work. The area of contact between the wheel and the work is increased as the diameter of the work increases. This applies to both internal and external grinding. The larger this area becomes, the softer should be the wheel. The right combination is often found by testing different wheels of varying degrees until one is found that gives best results. This is practicable on production work, but on tool and experimental work it is not so often possible to get just the right wheel for the job. The next important consideration for best results is the speed of the wheel. First in this connection is the matter of safety. All modern grinding wheels are designed and built to run at a certain (Continued on page 141) ° This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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Om- ce of y are solve does fore right laing Tade rided hard ever, Ss of f the f the wheel ness soft, rking away ruing ; not ‘| de- 288 of bya f the rough 1es to grain wheel ig 40 for a r the r it is , how d the e too resist ' time rasive n the d, the it has p and Con- cause heat. s and S. ion of of the on the as the This ternal comes, found arying es best juction 1 work ust. the on for wheel. tter of els are certain February, 1925 —_— Better Shop Methods Success in Grinding (Continued from page 140) speed, both with the idea of safety and highest cutting efficiency. The wheels are tested before leaving the factory and the safe speed is marked on the label accompanying the wheel. This speed never should be exceeded. It often happens that the label is lost or mutilated and this important infor- mation is not readily at hand. Roughly, a surface speed of one mile a minute for any kind of a grinding wheel is a fairly safe: rule to follow when in doubt, and this is not far from the actual speed specified for any wheel. The makers generally advise a speed ranging between 5000 and 6000 ft. a minute. Never exceed 6500 ft. a minute without special in- structions. REAT care should be taken in mount- ing a grinding wheel on the machine spindle. It never should be forced on, but must be a free sliding fit. If the wheel is too tight, scrape out the lead inner lining to make it go on freely. A pad or washer of heavy cardboard, rubber or felt must be used on each side of the wheel between the flanges. The nut is never to be set with excessive pressure, as there is danger of starting a crack that will weaken the wheel. It is good prac- tice and a safety precaution to examine a wheel before placing it on the spindle, to see that there are no hidden defects that might cause it to break. In all grinding operations it is important to have the wheel running true. The best results are obtained by truing up the wheel often. On some kinds of work this may mean truing up after each piece. On production work of a light character, perhaps a dozen or more pieces can be ground before it is necessary to true up the wheel. If the machine is running steadily all day on one kind of work, it is good prac- tice to true up the wheel about every 30 or 40 minutes. This insures against clogging and keeps the wheel always sharp so that it will do its best work. A diamond should be used for truing. ps COMMON practice, grinding is classified as “‘wet’’ and ‘‘dry.’’ Produc- tion grinding is usually carried on by the wet grinder. Wet grinding requires a lubri- cant, either plain water or any one of many grinding compounds. These com- pounds are usually some soapy substance mixed with water. A grinding compound is best for all practical purposes; it eliminates the tendency of the work to rust and gives a much better finish. In Figs. 1 and 4 (page 98) is illustrated work done by the wet grinding process. Figure 1 shows a machine set up for grinding crankshafts and a close-up of the job. Grinding crankshafts is a job that has become highly specialized. It is now commonly done by what is known as the wide-wheel method. In many cases the machine is specially designed and there Is no lateral movement of the wheel. The wheel is fed directly into the work (Continued on page 142) POPULAR SCIENCE MONTHLY [YAGNAVOX Radio Receiving Set TRF-5 with Reproducer M4 « $125.00 XPERIENCED radio users have stated that this Magnavox equipment (illustrated below) represents the highest standard of real value and usefulness ever offered in the radio field. & The Magnavox 5-tube circuit is a special development of tuned radio frequency in which a splendid balance of selectivity, range and volume have been attained. The one dial Station Selector eliminates all tuning adjust- ments; while the Magnavox Reproducer insures sonor- ous, pleasing tone for all programs. Magnavox Radio Receiving Sets, Tubes and Reproducers are carried by reliable dealers. Illustrated booklet on request. THE MAGNAVOX COMPANY OAKLAND, CALIFORNIA New York: Chicago: San Francisco: 350 West 31st Street 162 N.State Street 274 Brannan Street Canadian Distributors: Perkins Electric Limited Toronto, Montreal, Winnipeg 2R NEW VEST POCKET | ADDING MACHINE @ Adds as rapidly and accurately as alae : machine, yet fits the vest pocket. # echanically perfect. Easy to operate BA —nothing to get outof order. Everyone§ who uses figures should own one. Counts Up to 999,999,999 : Total visible at all times. A pull of the finger clears it. Don’t carry a pocket full of pencil stubs and scraj ae paper todo your figuring. Carry a Ve-Po-Ad. > 10 Days Trial Send no money, Easyto Draw Cartoons Just name and ad- When Shown in the RIGHT WAY dress and we will send machine yy se e Some of the cleverest cart ist d i ti ) Pay postman on delivery $2.95, it for learned how to draw in thelr aaaae ions sy pete | 10 days to prove it does all we claim. If Cartoonist Evans’ Simple and Easy to Learn Metho j, not nig yo A —— ee your and are now MAKING GOOD MONEY. Send one of Gettabtakddina ties mace Mae. Oe a ond let Mr. Evans see if you have ability s D., f° and receive t tfoli i BB 170 W. Washington St cio TL e Portfolio of Cartoons and full details THE W. L. EVANS SCHOOL OF CARTOONING © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See Page 33. — about the course. It i t ive. ( ———— Here’ - money maker. Everybody is not expensive wants one. Splendi rofit, rite f A ia E | T for special offer, . 825 Leader Building Cleveland, Ohio —_ KBE SELINA OK, TER ESE DIET St wom

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POPULAR SCIENCE MONTHLY The Perfect Four Tube GREIFF DOUBLE SELECTOR MULTIFLEX KIT Comblete literature that’s educating as well as interesting. Just ask your dealer “—“"or write direct for assortment No. 2, containing blue prints of wiring diagram of circuit. Just drop us a line giving your dealer's name and address. RRADIORECEPTOR(O. © Circuit-Loop Operating This wonderful circuit uses four tubes and has two stages of radio frequency, a crystal detector and three stages of audio frequency. Developed by the Research Engineers of the Radio Receptor Com- pany, working under the direction of Lieut. Greiff, of Super Heterodyne fame. The tone quality is really captivating. No station too far away to be brought in consistently. It can be assembled by any one in a few hours. For simplicity and ease of tuning, as well as power and quality of reception, it is far superior to a 5-Tube Neutrodyne. $29.50 Containing principal parts $50.00 Including all parts “ee 59 Bank Street New York City Only*10Down Buys This Fully Guaranteed BurroughsAddingMachine Balance in easy Payments Thisis a standard Burroughs Machine used in banks, offices and stores everywhere. It has been com- pietely overhauled and worn parts replaced. It is guaranteed for the same period as a new machine. Take advantage of this remarkable eg Offer today—pay only $10 down and M | let the machine pay its wayin your alt business. Total cash price only 4 100. ] his Other styles and sizes in leading makes of figuring machines. Today 52 Soe BAA EN A General Adding Machine Exchange 6809 Second Blvd., Detroit, Michigan Please send me information about this special guaranteed Burroughs Adding Machine. Name Business cae | 5 Address, ; i Be soe Te a eS ER | In Licensed by ane Been Raaio manutscwe'? ad NEUTRODYNE,; - Other Patents Pending 'S0oa¢§ S Pat-Off snbey ed U 4 Howard 5-Tube Neutrodynes in Chicago Success- fully Brought in European Stations on Recent Trans- Atlantic Tests. If Your Dealer Cannot Demon- strate Them to You, Write for Information, Giv- ing Dealer’s Name. ter Shop Methods Success in Grinding (Continued from page 141) with the hand-feed screw. Stops are set for the size of the pin and the diameter is checked with a dial test indicator at. tached to the machine. The wheel, of course, corresponds to the length of the pin and is made especially for each size of crankshaft being ground. A GREAT variety of work can be done by the wide-wheel method, and now machines have been perfected that pro. duce finished parts much more rapidly than the old center-traverse methods, The most recent in GRINDING WHEEL , development this line is the cen- terless grinder shown in Fig. 2. This method is a radical departure t from all previous =. a practice. The operation of the machine is con- tinuous. The work, FEED , being fed into the WHEEL Ne sae machine, passes Fic. 5. Di between . two showing principle of wheels, which are the centerless grinder set in relation to each other to produce a_ grinding and feeding action, as shown diagram- matically in Fig. 5. The work is sup- ported by a rest, and the grinding wheel presses the work against the rest and also against the regulating or feed wheel. Both wheels are usually of the same material with a surface sufficiently rough to prevent any slipping of the work. In Fig. 3 is shown the wide range of work the centerless machine will handle. It is claimed that by this method, under manufacturing conditions, it is possible to produce work accurate as to size and uniform in quality of finished product. This is aside from production gains. Another innovation within the past few years is a type of machine using a wide wheel (Fig. 6). This is known asa ‘plunge grinder,” as the wheel virtually is | ° plunged into the work or against a stop set to obtain the desired size. Although built along the lines of the familiar center grinder, the wheel does not traverse the work, but is wide enough to cover the whole length of the piece being ground. [N THIS type of machine, the wheel is working to capacity at all times. It is claimed that the wheel requires less fre- quent truing for a given number of pieces. The wheel can be fed into the work either by hand or automatically by power. The wheels for the machine illustrated are 20 in. in diameter and from 2 to 7 in. in width. Internal grinding, that is, the finishing of cylindrical holes, is accomplished with the aid of internal grinding attachments for standard machines or by special in- ternal grinding machines. The spindle speeds for these machines are consider- ably higher than those used on the ex- ternal type, although the surface sp2ed of the wheel is not necessarily higher. (Continued on page 143) © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. —~m =“ es owt ast ww mS Mm —— a: 6 |e eee eee ei fa. ~~

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re set ater is r at. el, of of the h size > done d now t pro- apidly thods, ss fre- pieces. : either power. strated (0 7 in. nishing d with hments sia] in« spindle nsider- the ex- peed of — February, 1925 Tretter Shop Methods Success in Grinding (Continued from page 142) Although usually done dry, some of the special machines for internal grinding are equipped to use water. The wheels are somewhat softer than those used on ex- ternal work, as the area of contact of the wheel with the work is greater. If the wheel was hard, it would glaze rapidly and heat up the work so that it would be impossible .to take accurate measure- ments. Tool and cutter grinding is usually done dry, sometimes with special attach- ments for the standard machine, but more often on machines specially de- signed for tool and cutter grinding. The wheels should be soft, as they are almost always grinding very hard materials and a hard wheel would be very apt to burn a delicate cutting edge or draw the temper of the tool being ground. In grinding cutting tools, such as taps, dies, reamers, milling cutters, and the Fig. 6. Front and end of a recently de- veloped 12 by 18 in. plunge grind- er, using a wide wheel like, the wheel should never be forced. Light cuts should be taken so that the wheel will not wear away too much be- fore the cutter has been once around, as any wear on the wheel will result in an out-of-round cutter or reamer. Another important consideration in grinding tools is to keep the wheel moving across the work when it is grinding. If it is allowed to rest in one spot, it may burn the edge or produce a low spot in the tool. The relative advantages of wet and dry grinding are somewhat undecided. All kinds of tools are ground dry, but some of the special tool grinders use water or a grinding compound. This undoubtedly is an advantage in grinding twist drills and heavy forged lathe and planer tools. On production work the coolant serves two purposes: It keeps the work cool and produces a better finish. This has been demonstrated in practice so that wet grinding is a decided advantage in most production work. The photographs used in Figs. 1 and 4 are published through the courtesy of the Landis Tool Company; those in Figs. 2 and 3 through the courtesy of the Cincinnati Milling Machine Com- Pany, and Fig. 6 through the courtesy of the Cincinnati Grinder Company. POPULAR SCIENCE MONTHLY FARAWAY GETS STATIONS FAR AND NEAR—LOUD AND CLEAR What FARAWAY Users Say: Gets Europe and Coast to Coast Your model F is sure some set. I get stations from coast to coast and I also had several European stations last night loud and clear. I’m going to order some more machines very shortly. R. A. SCHAEFER, Box 104, Rhome, N. Dakota. Got Europe and Five Orders Demonstrated your Model F last night at a party ‘and got Havana, Los Angeles, Oakland and five European stations in silent hour. Sold 5 com- plete sets. Enclosed are orders. Rush. J. D. SHOPTAUGH, Bellevue, Ky. “‘Crazy’’ about Far- My customers are just crazy about Faraway sets and I sell them as fast as I order them. We readily pick up_ Boston, Dallas, many other stations. R. J. ADAMSON, Brampton, N. D One Sells Another I cannot imagine how you can manufacture these Far- away sets and sell them at your retail price. I have been interested in radio sets for several years and I recently had the privilege of “listening in’’ on one of your 4 tube sets and was surprised at the wonderful results. Send me_ your literature at once as I want to buy one. Batteries. Salt Lake City, Utah. Got 30 Stations the market 3 Your 4 tube Faraway is fine. So far I’ve tuned in 30 known stations on the Loud Speaker. Send me a supply of order blanks and litera- ture and expect many more A.E. CRAFTS, MODEL F QOD COD 556) orerird sioverehecsrsieeis MODEL R TOMS ADOVO) 268.5 e eked: wake European and other Foreign Stations received by FARAWAY Users Faraway Radio Sets stood the Big Test. of Rhome, North Dakota, was the first to report his success. He Frisco, Pittsburgh and writes “I get stations from coast to coast and I also had several European stations last night on the loud speaker, loud and clear.” Mr. J. D. Shoptaugh of Bellevue, Ky., Ed. J. Siek and many others report similar success. Operates Dry Cells or Storage Battery Faraway sets are easily tuned, extremely simple to operate and always dependable. The latest improved type of set construction used only on high priced sets is employed. You, too, can own a FARAWAY with our unique money-saving plan You take no chance for we GUARANTEE SATISFACTION or REFUND MONEY BE. ON. OS We guarantee all the things our users claam—namely—clear, sweet tone—fine volume—coast to coast reception—can be logged—no tube howls, distortion of radiation. Furthermore, there are fewsets on elling for under $100 that can compare in beauty and workmanship with the Faraway Model F for $59.50—you'll agree with us when you see it. For Faraway Cabinets are ornamental and massive—beautifully done in mahogany. The panel is finished in dull pataum with all calibrations finely etched in A era SO WHY PAY MORE? You'll wonder, like Mr. Johnson, how we sell Faraways at these low prices. OUR orders. answer. Don’t buy your radio set until you see Faraway. surprise for everyone who writes td our literature and, money enving proposi- Pittsfield, Mass. ' tion. Mail the coupon TODA ® 4 tube set for use with loud 1$59. 50 2 tube set shown in illustra- $99.50 7 Mr. R. A. Schaefer They operate with either Dry Cell or Storage UNIQUE SELLING plan is the We have a big ‘_DEALERS—A GEN TS Our Faraway proposition offers tremendous possi- bilities for you. Write quickly for plan and territory. THE FARAWAY RADIO CO. 653 W. 3rd Street, Cincinnati, Ohio H | THE FARAWAY RADIO CoO. Cincinnati, Ohio. { Gentiemen: Without obligation send me: O Your literature and details of money-saving proposition. O Agents’ Proposition. | O Dealers’ Proposition. l Address- | City and State- GLASS O5¢P IN BUY a FROM THE MAKER CATALOG FREE Either pin shown made with any 3 letters and 2 figures. 1 or 2 colors enamel, Silver plate 257 4 ea. $2.50 doz. Sterling silver. 40¢ ea.. $4.00 doz. & BASTIAN BROS. CO. 591 Bastian Bidg., Rochester, N. Y. Unusual oppor- tunity is offered Mr. Brush Salesman for aggressive, ambitious, hus- tling men to represent an old established manufacturer of high grade, guaranteed, fastest selling line of Sanitary Twisted in Wire Brushes, sold direct to the Home. We have openings for experienced brush men as managers in all territories. We want live wire, energetic Go- Getters. We pay larger commissions than any other Brush House in the Country. If you want to earn some real money, it will pay you to write us immediately for our proposition. WIRE GRIP SANITARY BRUSH CORP., 15 Mercer Street, New York City. © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. “The New Colonials” 50 Houses—6 to 10 Reoms—$1 *‘All American Homes” 50 Houses—7 to 10 rooms—$1 “South-West Stucco Homes” / 75 Duplexes & Bungalows—$1 ‘West Coast Bungalow Books” 5 to 7 Rms. $1; 3 to5 Rms. $1 E. W. STILLWELL & CO., Architects, 288 Calif. Bldg.. Los Angeles BUCHSTEIN’S FIBRE LIMB is soothing to your stump— strong, cool, neat, light. Easy payments, | sooner al for HOMES Braces Guaranteed 5 Years for all Send for Catalog Today deformities P. BUCHSTEIN CO., 610-3ed Ave., So. Minneapolis, Minn. See page 33. FB6 Tae A EY ONES ees

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POPULAR SCIENCE MONTHLY Wz SGSaSSSRTRRT eee eases eeesest formance. table mounting. At dealers everywhere. DON’T GAMBLE in building your set by using inferior parts. You chance the loss of considerable time, money, and patience if the results aren’t satis- factory. Be certain! Use only Amsco parts. Made by men who really know their business, they lead the field in all around per- Amsco Parts necessary for those who construct their own include the Low Loss Condenser, a laboratory instrument designed for perfection in set building. Also the Amsco Rheostat, for perfect filament control with all types of tubes and the Amsco Tube Socket with genuine Bakelite Base suitable for panel or Free literature on request ee $25.00 in PRIZE See top of page 10 in front of book for details Special Limited Pine Offer Gives You This Ideal Home for $1095 Only a Limited Number Will Be Sold at This Rock Bottom Price ERE IS a home so easy to con- struct that a member of your family (or a friend) can help you build it in a few days. Bossert’s easy, convenient plan of building saves you $500 to $2000. No architect’s fee to pay, no builders’ waste, no costly construction delays. The Albany Model is one of our most ular homes. It has four large rooms and ath, all carefully planned for greatest com- fort and least housework. For a limited time only it will be sold for this low price. Lumber is delivered “ready cut.” The low price of $1095 includes full plans and specifications; lumber; millwork; plaster boerd; hardware; paint and varnish. Bossert quality and service guarantees satisfaction. Stop paying rent. Own your home at a most unusual saving. NOW is the time to buy, and THIS is the house to own. Send today for illustrated Booklet showing how to finance your building with small first payment, balance after delivery of house. Louis Bossert & Sons, Inc. Largest Lumber Plant in the East (House Dept.) 1310 Grand Street BROOKLYN, N. Y. The Question of B Battery Current Solved with the Kellogg Trans-B-Former THE Kellogg Trans-B-Former furnishes the necessary plate voltages for your radio‘set, from your 110 A C, 60 cycle, electric light socket without any inter- ference. This unvarying current is furnished at less than one- fifth cent per hour. ‘Throw away your “B” batteries and install a Trans-B-Former and your set will operate at maxi- mum efficiency constantly. The Kellogg Trans-B-Former will: Improve reception Reduce operating cost to a minimum Add to the appearance of your set Developed, perfected and guar- anteed by the Kellogg Switch- $ board and Supply Company. At Your Dealers KELLOGG SWITCHBOARD G&G SUPPLY COMPANY 1066 Adams Street Chicago, III. New Transmission Controls Speed of Machine Tools sree controlling the speed of machine tools and various types of machine the variable speed transmission illus. trated below was developed recently, As applied to a drill pregg the device al. lows the speed to be increased or retarded without stop. ping the drill or shitcing belts or gears. The ma- chine may be reversed atonce Drill press fitted with new transmission and control mechanism with cover raised The transmission may be applied to lathes, milling machines, boring mills, and other machine tools, as well as to drills, The mechanism is entirely inclosed and operates in a bath of oil.—A. P. C. Shop Loading Platform Built to Resist Hard Usage M?st of the loading platforms for lift trucks go to pieces in a short time, whether commercial or shopmade. The platform illustrated has been in competi- WAGON BOLTS AS IEG. thi yy 7 1/2" PLANKS A heavily built loading platform of a gen- erally useful size, and details of the legs designs. the platform together. tion with other designs long enough to prove its superiority over the more usual The special features are the cast-iron leg and the method of putting tS] This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. Feb az.

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ssion ‘aised plied to vills, and to drills, ysed and ~ Je Built | se is for lift ort time, de. The F a gen- the legs nough to 1ore usual ; are the of putting ll How Would You Machine This Awkward Piece? ERE’ S an interesting machine-shop problem for you. Do you know a better or quicker method of machining the piece illustrated below than that described by the contributor? If you do, send a sheet showing the opera- tions, with whatever explanatory sketches are necessary, to the Editor, Better Shop Methods Department, PopULAR SCIENCE MONTHLY, 250 Fourth Avenue, New York. For each solution that is suitable for publica tion, POPULAR SCIENCE MONTHLY will pay four dollars. a5 =» SIE HE piece shown in Fig. 1, a tool-steel cam, is to be machined for an experi- mental job. No special tools are to be used, as only one piece is required. How would you do it? As a manufacturing proposition it would present no unusual difficulties, but when only one piece is to be made, the % DRILL AND “OUNTERBORE 46 DEEP ~s. VERTICAL MILLING- — MACHINE TABLE = — CAST IR FIG.3 FIG.4 Steps in machining the cam and iron plate for attaching it to a faceplate | Problem is different. I shall describe the methods used in making this piece in a New England shop and ask the readers of (Continued on page 146) ‘ina Methods | POPULAR SCIENCE MONTHLY Why I am the LARGEST OPERATOR in the World I have built this chain my students the _ best by putting every cent back into new equipment for you. The success of this method is easily seen —I am the youngest— but by far the largest and most successful operator in the world. Your future is safe in my hands. though. McSWEENY cna execrercat ; Dept. 2610 McSweeny Bldg. 517-19-21 South Laflin Street Cincinnati, 0. Chicago, Ill BE AN AUTO,TRACOR, o ELECTRICAL EXPERT / If you are. earning less than $50 a week, read every word. Why stay in the old job, with no future—no chance of ever earning much more than you are now? The Auto, Tractor and Electrical Business offers thousands of BIG PAY JOBS—jobs where you are the BOSS. Get out of the rut—be independent—he an Auto Expert. The World’s Largest Operator of Auto Schools Will Train You I am the largest operator of Auto, Tractor and Electrical Schools in the world! Think a moment what it means to be trained by McSweeny —the biggest in the industry—Think of the prestige—the ease of getting a big job, when you can say ‘‘McSweeny Trained me!”” That’s the magic phrase that has opened the doors of thousands of big pay jobs to my students. Eight Short Weeks and then & —SUCCESS Think of it—eight short weeks in any of my schools—Then You don’t have to know a thing : about cars—you don’t have to have any education—all of schools by giving to you need is the determination to get ahead. In eight weeks Stor. : you'll be, not merely a Garage Mechanic, but an Auto, training in the country— =‘ Tyactor and Electrical Expert —by building the Schools FREE R. R. FARE and BOARD c= ° ° - ° Mu = For_a very limited time, I am going topay )i% THE your Railroad Fare to my nearest school— /@g& and board you absolutely free while yon are there—And in addition, I am a big pay job—success! a big-pay man. 145 m'swe going to make you a very special tuition offer. Send today for my free catalog. You'll have to hurry, SCHOOLS THREE BIG SCHOOLS USE THIS COUPON FOR —_— eS eee J. H. McSweony, Pres.. Dept. 2610 McSweeny Auto. Tractor & Electrical Schools, McSweeny Site. Cincinnati, Ohio 517-19-21 South Laflin St., Chicago, I. McSweeny Bidg., Cleveland, Ohio Send this coupon to the School nearest you Dear Mac } Let me have the full details of your special offer. Corer reser enrsseereeeeeesesesesce (No facilities for colored students) That lamp has always needed a new shade and now it’s going to get it! Easy enough with Klein Pliers. A pair of Klein’s is a real worker and a real playmate. You'll enjoy them for making and fixing things all over the house—for your radio and auto, too. They’re thor- oughbreds, are Klein Pliers—the re- sult of sixty-seven years of manufac- ture of pliers. Elec- trical and telephone companies all speci- fy them. Pick upa pair when at your hardware dealer’s. peor NOLEN coesirs © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. FIND {LE YK a N LS 9) | 2) ee ees

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Ee essa matinee tl nese cee ae SRE A Reg a ESE Oa ee omen le ana hte i ito heen pee ar nape pre aoa =r liane ndcananeianemeanie: ae rape ea eae aoe ~ ee a eae pores eens Sa ener eer — ae fee Sa A erase ee cr ee 5 o Peres g terse POPULAR SCIENCE MONTHLY

Further Adventures of BURGESS RADIO BATTERIES

U. & U. Photos. The Shenandoah is Equipped with Burgess Bat- teries and MacMillan Carried them to the Arctic If the quality of any product may be judged in part by the standing of its users, surely Burgess quality must be considered unusually high. Burgess Radio Batteries are found where there’s need for the most effi- cient batteries made—in emergen- cies where failure brings disaster— with explorers in far-off lands—with the unsung heroes of the air serv- ice—beneath the seas with the crew of the submarines. “ASK ANY RADIO ENGINEER” Send forthe Burgess Radio Compass. Surprising—amusing and interesting to the entire family. Sent free of charge from 187 Burgess Engineer- ing Bidg., Madison, Wis. Write for it. BURGESS BATTERY COMPANY Engineers DRY BATTERIES Manufacturers Flashlight - Radio - Ignition - Telephone General Sales Office: Harris Trust Bldg., Chicago. Laboratories and Works: Madison, Wisc. In Canada: Niagara Falls and Winnipeg Pn | ino. 61% fs: g > TBURGESSIME i iii tad TA" 7 | . we, A atts 0, GURGESS (BATTERY) ie ui IBATTERY

Better Shop. Methods Simple Indexing Fixture Aids in Grinding Gear Cutters SIMPLE fixture for holding gear- tooth milling cutters while grinding may be made as shown. It consists of a cast-iron plate, mgchined all over, pro- vided with a stud for’ hvlding the cutter, and bolted to the . machine table. A ' stop finger, which | is adjustable for | cutters of varying sizes, is provided. The cutter is placed on the stud 4 and the finger is’ adjusted so that ; the face of the * ¢ 4 ‘

‘or grinding gear utters quickly

tooth is at right: angles to the whee! spindle. No nut is n cutter, which can be easily by hand. é How Would You Machine This Awkward Piece? (Continued from page 145) POPULAR ScrENCH Mon¥HLy for a better Hed to retain the tated or indexed

4 or easier way. ; A piece of ~- 34 in. long was pla o the dimensions shown in cross secti (Fig. 2), leaving about .010 in. to be gruund. Ona surface grinder the sides were ground square and parallel. The work then was laid out on a sur- face plate and the 4 3/82-in. radius was scribed. The piece next was set up as shown in Fig. 3, in a toolmaker’s vise bolted to a circular milling table on a vertical milling machine. The piece was trued up to the line with a pointer clamped to the mill and the vise was bolted securely. The 4 3/82-in. radius was milled to the line for a depth of 54 in. This operation also finished the face A (Fig. 1). The next operation was to drill and countersink the holes. The 434-in. radius then was finished in the lathe by the use of a cast-iron plate, planed as shown in Fig. 4. ; The cam was fastened firmly to the plate with 3-in. cap screws and the plate was bolted to the lathe faceplate. The work was trued up with the 4 3/32-in. radius already milled. plate had been left long enough to be turned off so that the circle could be measured with a micrometer, as it had to be exact. The other curved surfaces were not so particular, but could not be turned readily in the lathe on account of the difficulty of holding the piece. The 34-in. concave radius was made with a mill 114 in. in diameter and the 34-in. external radius was milled to the line as closely as possible and finished with a file. The other operations were comparatively simple and need no special comment. The main difficulty is to machine the circles and there is little room to use a strap strong enough to hold the piece while roughing off the surplus stock.— H. L. W. Vg in. square by

Febr Uary, 1935 Canada where Dairy Fann prs iA) Ls <AMER

" . . 4 af rorts FAN “v1 ister: Western Canada, blessed with low. priced fertile land, a favorable climate and an abundance of pure water offers remarkable opportunites to experienced dairy farmers. The rich fertile soil on which nutri- tious grasses and feed of all kinds grow profusely, can be purchased at an average of $20 an acre—with free use of the land for a year and then 35 years to pay. The yearly payment on an average 160-acre farm is only $195.30. Think of it. Cash is paid for all dairy products, most of which are used in the nearby cities. Since 1900 the value of Canada’s dairy industry has increased $164,000,000. Last year alone Canadian dairy farmers put $54,308,334.04 in their pockets. . Come to Canada where you can put your rofits in your pocket, where land prices are ce and feed is cheap, where you can double or treble your acreage with the same invest- ment. Both irrigated and non-irrigated lands are available. Investigate now. Send the coupon for full information and details about special inspection trips at reduced fares,

Do it now. M. E. THORNTON typ Supt. of Colonization oo Dept. 512, | Canadian Pacific ered Railway Depot ey hy Lis) Winnipeg, Manitoba, Canada ae EER RRR ERR RERRERSE ES I ‘ M. E. THORNTON, Supt. of Colonization & Dept.512, Canadian Pacific Railway Depot 4 Winnipeg, Manitoba, Canada , I am interested in learning more about: 0 Prairie Provinces of Canada. 0 Irrigation Farming in Sunny Alberta. Business and Industrial Opportunities in Western Canada.

My Name. Address.

2.8 82 2 2 2.8.88 Town State oy SESBBBRBRBRBEEEERBPSERBESEEERE REED

The cast-iron |

‘(S) This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. ‘foe bl at Tex ouble 50% More Penner The AIR FRICTION is the ONLY Car buretor which changes ordinary into powerful, super-heated DRY GAS VAPOR which burns up clean, prevents carbon and nearly doubles power and mileage. Leaves no unburned it to run down into crankcase, destroy lubrication and grind out bearings. Motors live two to three times as long with Air Frie tion. Fords guaranteed to make 34 miles to gallon. Othet cars in proportion. Try Air Friction 30 days at our < Money back if you want it. Agents wanted. Write today. AIR-FRICTION CARBURETOR COMPANY / 1519 Raymond Building Dayton, Ohio, U. S. A

We havea wonderful new copyrighted system of teachin music by mail! To first pupils in each locality we will give free superb Violin, Tenor Banjo, Ukulele, Hawaiian-Guitar, Banjo, dolin, Banjo-Ukulele, Ban, ios Mandolin, Cornet or Banjo-Guitar lutely free. Also teach Piano and Organ. Very small lessons only. ‘our lessons will teach you several pieces. Ove 100,000 successful players. We guarantee success or no Complete ou ree. ite lay, Dept.166, No ob! Slingerland School of Music, 1815 Orcharg St., Chicago, lh

ef bn a BS eb ee oh” Ca es a ee oe ME OO Fr ee aE Se Sere t+ a 2 a

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Ty, 1935 0. MEF VEE on and grind out ng with Air Fric to gallon. Othet ys at our risk, Write f° OMPANY Ohio, U. S. A February, 1925 POPULAR SCIENCE MONTHLY 147 New Wonder of the Seas (Continued from page 36) Twenty horsepower is produced by the two motors that spin the towers at the rate of 120 revolutions a minute. They take out of the wind about 1000 horse- power. The inventor claims that each tower produces about 15 times as much propulsive power as that of a similar sur- face of canvas. An auxiliary engine is used for getting the ship in and out of the harbor. ; When the two cylinders are turning at the same speed and the helm is not put “on,” the Flettner ship sails normally at right angles to the wind. Changing the speed of one cylinder is said to alter the ship’s course just as changing the helm would. N. W. Akimoff, general manager of the Akimoff Propeller Company, Philadel- phia, recently has given an explanation of the Magnus Law as applied to the Flett- ner ship. He begins by considering what would occur if the two cylinders on the Buckau were stationary and the longest dimension of the ship were at right angles to the wind. In that case, says Mr. Akimoff, the wind going around each cylinder would be evenly divided so that there would be no action on the ship. Then, suppose there were no wind, but that the cylinders were spinning at the rate of 120 revolutions a minute. [ps layers of air directly in contact with the moving cylindrical surface would revolve with practically the same velocity as the cylinder. But in the case of the Flettner ship, there is a combination of the two preced- ing cases—the cylinders spinning and at the same time wind acting upon the ship. Then on one side of the cylinder, the velocity of the wind is opposed by the velocity of the air adjoining the cylinder, thus retarding the velocity of the wind. This means an increase in pressure. On the other side of the cylinder, the opposite is true. The velocity of the wind combines with the velocity of the air layers next the cylinders, resulting in a decrease in pressure. On one side of the eylinder there is an increase of pressure, on the opposite side a decrease, so that there results a strong force from the stronger to the weaker pressure. This causes the ship to move forward. THE magnitude of this effect, Mr. Akimoff says, may be computed by multiplying the following quantities: | The density of the air, the velocity of the wind, the peripheral or surface velocity of each cylinder, the circumference of each cylinder, and the height of each cylinder. ‘In the case of one of the cylinders on the Buekau, considering the velocity of the wind at 40 feet a second, the forward thrust due to the moving cylinder would be 12,000 pounds. Actually, this would be reduced, on account of various losses, to the extent of 10 per cent. Tests are said to have demonstrated ‘that nearly double the speed made by a sailing vessel equipped with sails can be made by one with the rotor equipment. On its trial voyage the Buckau developed (Continued on page 148) ee Surface leakage exceptionally low with this panel built to order for radio HE needs of radio are special. Radion is mechanically right, too. Better results have invariably It resists warping. No special tools followed the use of apparatus and are needed to make a clean-cut work- material designed for its own unique manlike job. Everybody knows that demands. it is easy to cut, saw or drill. Comes in Radion is a special material,developed eighteen stock sizes, two kinds, Black to order by our engineers to meet the and Mahoganite. needs of radio. For radio-frequency Better performance will make it insulation its characteristics are highest worth your while to ask for Radion by ; as proved conclusively by authorita- name, and to look for the name on the $ tive laboratory tests. Surface leakage envelope and the stamp on the panel. and dielectric absorption are shown to Radio dealers have the exact size you be exceptionally low. want for your set. You can see the difference Send for booklet by the finish “Building Your Own Set’’ You can see that Radion is different if Our new booklet, “Building Your you look at the finish. Own Set,” giving wir- That high-polished, : ing diagrams, front satin-like surface is not Other Radion Products and rear views, show- only good-looking but The same qualities of low- inz a new set with slanting ful ll. Mois- loss insulation and attractive panel, sets with the new userul as wen. appearance characterize Radion built-in horn, lists ture and dirt cannot Radion dials (to match panel), of parts and directions for gather to form leakage —— post — ee building ered eer es ad nobs, etc.—also the new circuits—mai or ten paths = nd cause leak- Radion built-in horn. cents. age noise. Mail coupon today. AMERICAN HARD RUBBER COMPANY, Dept. PS 2, 11 Mercer St., New York City ; Chicago Office: Conway Bu Iding Pacific Coast Agent: Goodyear Rubber Co., San Francisco—Portland American Hard Rubber Company PS2 11 Mercer Street, New York City. Please send me your new booklet, “‘Building Your Own Set” for which I enclose 10 cents The Supreme Insulation (stamps or coin). © P AN E LS WORE isc ie sc nec ete dhees teasva Ceeee wee Dials, Sockets, Binding Post Panels, ete. Fords Get Double Mileage With New Invention Simple Device Works Wonders The most amazing von remarkable ne Saag nar that has come to light in recent years has just : been produced by Robert Martin of Chamber- ALL the latest im- “* proved apparatus is listed in our monthly bul- lain, S.D. Fords that were formerly making only 12 to 14 miles on a gallon of gas are now getting from 28 to 43 miles, by using this new attachment. This marvelous invention is a simple affair of aluminum and glass and can be installed by anyone in just a few minutes. letin: ‘‘The American Radio Transmitter.” If it’s new we have it. © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. In addition to increasing mileage, it filters Lowest Prices in U.S. f every drop of gasoline fed to the cylinders and — Lnypage qa are the removes every particle of carbon at the same All patiouaiie "aduaieame time. .Mr. Martin guarantees it to increase gcods.ct disseunts that make yon real money. ae mileage on any car and is willing to give one get your name on our mailing list, Simply send name free tc any person who will help him introduce Spent, for, latest. bie monthly bulletin, showing 75 na- it. Write Robert Martin, 800-17 Somers Bldg., AMERICAN RADIO MFG. CO. 6 W.14th St. Dept. 8, Kansas City, Mo. Chamberlain, S. D., and ask for his free sam- ple offer.

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os 2 Pe 3 Si Lee tae = wediadaawads win sai war a POPULAR SCIENCE MONTHLY _ NEW Youth-Giving Belt Reduces Waistline ~ Quickly Instantly makes you look inches thinner and years younger and actually massages away fat every second while you wear it! ERE’S a new easy way to get rid of that bulky, useless, disfiguring fat without any effort on your part! A new kind of belt has been perfected which actually takes off fat in an easy, gentle way—just like an expert masseur! .The moment you put on this new self-massaging belt your waist is instantly reduced from 2 to 4 inches! At the same time all your stomach disorders, constipation, back- aches and shortness of breath generally dis- appear-as the sagging internal organs are put back in normal place. You are filled with a wonderful new energy, and look and feel 10 to 15 years younger! Reduce the Way Athletes Do The Weil Reducing Belt is made of specially prepared and scientifically fitted rubber. It is so constructed that, as you wear it, every breath you take and every move you make imparts a constant gentle automatic massage to every inch of the abdomen. It works for you every second, day and night, and reduces much more rapidly than ordinary massage. The Weil Belt is made of the same kind of scientifically treated rubber that is used by hundreds of professional athletes and jockeys, because it not only reduces quickly but at the As shown below, every move of your body preserves their strength. It is time highly indorsed for its healthful principles by same physicians everywhere. Satisfaction guaran- teed or your money instantly refunded without question. SPECIAL TRIAL OFFER walking, climbing stairs—merely breath- ing as you sit—causes the Weil Belt to massage your abdomen, for you every second, It is working Write at once for full description and details of the Special 10-day Trial Offer being made to The Weil Company, 102 Hill Street, New Haven, Conn. Se ee eee Al gy THE WEIL COMPANY, x a a 102 Hill Street, New Haven, Conn. ; Gentlemen: Please send me without obligation E complete description of the Weil Scientific Reducing 5 Belt and also your special 10-day Trial Offer. & - E a - inp ea ces . Po cikeniceseaendtcence eee ctemenaveewewan i B = a H TOR on poli Cease eames Reon ass x pieeca B SER VERARERASCKRsEBSsSVssBaeasssnseewe ie a Day Pays for this Beautiful Rocker ‘ Over 1000 other bargains. Furniture, Rugs, Lamps, Silver, China, Blankets, Stoves, etc. Save Big Money at our Factory-to-Family prices. Pay as little as $3 down; up to a year and a half to pay balance. Get all your Furnishings at once—pay as you use. Thou- sands buying this new way. Big Catalog FREE New Spring ‘‘Larkin Book of Better Homes.”” Shows everything for parlor, rch, dining-room, bedroom, kitchen. argain Prices on famous Sympho- nola Pho ph Also Symphoni janos, Player. Pianos in genuine Mahvgany, Walnut, Fumed Oak. Free trial. Up to 4 years to pay. Satisfaction or money buck. heck below article interested in. 0 Home Furnishings (C0 Pianos or Players 0 Phonographs Cut out this adv.—write TO-DAY for FREE Book. Liatkin CB Inc. Dept. 240, BUFFALO, N. Y. Peoria, Ill. Chicago, Ill. Diay a SAX! € Have | oe . Nothingwill bring % (\ youso many Saxophone is easier to finger, easier to blow. DAYS FREE RIAL With our free lessons you ‘Sa. can be playing popular tunes in ashort time. You can get this wonderful instrument, with its superb tone and per- fect workmanship on six days’ free trial in your own home. Then if you decide to keep it you can take ten months to pay. Write at once for free saxophone book- let. Other York Band Instruments sent on the same easy terms. Free literature upon request. J. W. YORK & SONS Dept. 925-B Grand Rapids, Mich, February, 195 | convinced of its economic value that it | has decided to use the rotors in 10 new | freighters of 10,000 tons each to beem: | Janeiro will make a saving of 50 per cent, | will save from 35 to 40 per cent. | | | i New Wonder of the Seas | (Continued from page 147) an average speed of 4.5 knots (5.2 tna | miles an hour) in unfavorable Weather and in later tests the ship was able to | make eight knots (9.2 land miles). The inventor estimates that with | vessel somewhat larger than the Buckg it would take only 18 days to sail acrog the Atlantic to the United States, He is planning to make the trip late this ye after further experiments. A NOTABLE feature of the ship js said to be its ease in changing dires. tion. With its towers reversed it is pos. | sible for it to sail backward. A three! bladed rudder enables it to turn around in its own length. Any change in cour can be made without coming to a stop or slackening speed. Supporting Flettner’s claim to practic. | ability is his own reputation. Anton Flettner is not a newcomer in marine| invention. He is recognized by scientists as an experimenter along original lines An automatic rudder that he invented, few years ago is widely known and used, Professor Albert Einstein, originator of the theory of relativity, kas pronounced the rotor principle of great practical jm portance. The Hamburg American Steam. ship Company, for example, became go ployed on its East Asia route. On the East Asia route, wind condi-| tions are so favorable to the operation of the rotor ships that the company hopesto save fuel amounting to 60 per cent of that) consumed now. Ships equipped with the’ device sailing from Germany to Rio de! it is estimated, while those to New York One of the largest shipping companies in the world is reported to be contempla- ting using rotor ships as oil-tankers, and steamship lines even are considering them as possibilities for passenger-carrying vessels. IIE inventor himself does not assert that his device will be a substitute for steam or electric power on the high seas. But he declares that while the speed of an ocean liner equipped with revolving) towers would not be increased, the im vention would save a large percentage df its coal and oil, resulting in a great saving | in storage space, as well as in the cost of) fuel. An extremely important line of inquiry developing in the consideration of this device, is whether it will be possible to) store electrical energy, created by the rapidly revolving cylinders, in batteries) for future use. If this is possible, the! world will have a remarkable new meaii) for producing electrical current. Wind, the vast, unknown, unmeasured elemett,, could be harnessed in this easy way 0) propel anything from farm machinery 0) an electric power plant. ‘| Flettner has hinted of this. Wind power, he says, eventually may supe both coal and water power on account d its cheapness. | IS) This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. _ i Fe'

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ruary, 195 ein Seas Weather | 3 able to | 8). > With 9 » Buckay, ail ACTORS 8. Heig this year © ship is Ing direo. it is pos. A. three. | N around | in Course | a stop or © practic. | Anton | nN marine’ Scientists | inal lines, | nvented 9. and used, iginator of | ronounced | actical im: | -an Steam- became g0 ue that it, in 10 new to be em: | ind condi eration of | Ly hopes to ent of that | d with the | to Rio de 0 per cent, New York 3 companies contempl- inkers, and -onsidering er-carrying not assert bstitute for . high seas. speed of an revolving »d, the in rcentage of reat saving the cost of > of inquiry’ on of this possible to ed by the n batteries ossible, the new meals nt. Wind, ed element, asy way t0 ohio his. Wind y supersede account di) $$$ 33. February, 1925 == Henry Ford—‘‘There Is Always Room for More”’ (Continued from page 39) superintendents, foremen, and “straw posses” alike. And Henry Ford, being the supreme executive of them all, himselt circulates as they do, though through a i ea. eos —_— in and knowledge of the most minute details of the things that are peing done throughout his organization is rofound, which probably is not remark- able considering that he himself insti- tuted, or at least directed, the adoption of all these methods and policies. He is constantly alert to unearth new develop- ments that may be useful in his work of making better motors. About 500 new jdeas a week on the average are given a trial in the Ford organization, sometimes only on a laboratory scale, at other times in gigantic proportions, and the cost of this kind of research reaches a million dollars a week! oo hundred acres of flax recently have been harvested at Dearborn as a means of testing the advantages of linen over cotton in the manufacture of the cloth used in motor-cars. There is a plantation in Florida where experts are investigating methods of growing rubber. Sometimes -these experiments produce results of immediate practical utility, as for example, when Henry Ford’s scientists determined not long ago that rubber, asbestos, and straw, suitably processed, might be substituted effectively for wood in making steering-wheels for Ford cars. Sometimes such tests yield nothing, long as the experimenter has courage enough and energy enough to try again. Methods and processes that have been tested and adopted by the Ford organiza- tion are not kept secret, nor guarded in any way. They may be borrowed and utilized by any other motor manufacturer or any other industry. Engineers in the employ of André Citroén, sometimes called the ‘Henry Ford of France,’’ not long ago spent weeks studying the methods of the Ford factories with a view to adopting them in the manufacture of Citroén cars. They were given all pos- sible codperation. Now whither is all this leading? What may be expected of the Ford Motor Company of the future? We hear frequent prophecies regarding “‘flivver” airplanes. Often the opinion is expressed that in the future men will journey through the air in tiny, individual planes as casually as they now drive their auto- mobiles through the city streets. I asked Henry Ford a few days ago whether he ever considered the possibility that the Ford Motor Company might some day be turning its resources to the manufacture of airplanes. “We are, of course, interested in the airplane motor,” he replied, ‘‘as we are interested in every kind of motor. We took the lead in the production of airplane motors during the war. We have an airplane landing-field, and we are build- ing a mooring-mast for dirigibles. The (Continued on page 150) a which bothers Henry Ford no whit, so | POPULAR SCIENCE MONTHLY Koa STROSS 149 Buy a Studebaker Direct from the Maker” ay _ S — aa Latest \ u.!| Sale Geet Just $1.00! FREE! (aan For a limited time we are offering a beautiful Watch Chain FREE, Write now while offer lasts, Write for our Free Book. It will named on equal quality. of advance Watch Styles. 21 Jewel STUDEBAKER -the Insured Watch Choice of 54 latest, thin model, Art Beauty Cases in yellow gold, green gold or white gold effects; 8 adjustments, including heat, cold, isochron- ism and 5 positions. Direct to you from the factory —the value in America today! : ‘ ¥ Send at once and get a copy of Write for Style Book! Saszt spc: ecert scoPy.ef newest, beautiful, advance styles in Studebaker Art Beauty Cases and Dials. Read how you can buy a 21 Jewel Studebaker Insured Watch direct from the maker—save big money—and pay for it while you are using it. post you on watch styles and watch values. Send coupon at once. Get Free Chain offer today while it lasts, \erTiT/ AZ peasy \ a> The balance in easy monthly payments. You get the famous Studebaker, 21 Jewel Watch~Insured for a lifetime—direct from the maker at lowest prices ever Send at once for FREE Book STUDEBAKER WATCH CO. Dept, H23, South Bend, Indiana Canadian Address: Windsor, Ontario Mail Coupon for Free Book eet tryterkfecire outa STUDEBAKER WATCH CO. Dept.H23 South Bend, Indiana Please send me your Free Book of Advance Watch Styles and particulars of your $1.00 down offer. If you live in Canada send your inquiry to our Canadian office: Windsor, Ontario. i coenidiccieiecumniamnieentinane SS lie A | 0 Check here for Ladies’ Watch Folder. O Check here for Jewelry Folder. greatest watch PATENTS e REGISTERED PATENT ATTORNEY SINCE 1905 SENO FOR FREE BOOKLET HARLES W LOVETT Suni 806 (YAN MASS, ° ad PATENTS #2evees service noted for results, evidenced by many well known Patents of extraordinary value. Book, Patent-Sense, i. Lacey&Lacey, 648 F St., Wash., D.C. Estab. 1 PATENTS TRADE-MARKS, COPYRIGHTS AND PATENT LITIGATION rite for advice and instruc- tions how to proceed, costs, etc. Hand Book with illustrations of 100 Mechanical ovements sent free on request. ALBERT E. DIETERICH Patent Lawyer and Solicitor Successor to Fred G. Dieterich & Co Co. 681A Ouray Bidg. WASHINGTON, D. C., IONS mmercialized ON A CASH OR ROYALTY BASIS lye TNA 207 Tie INVENTOR 37d MANU z /n Business 25 Years - Complete laciitties References ADAM FISHER MFG.Co, 183-D St.Louis, Ma, © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. perth eared nrener RED ET

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Prove Your Right to Popularity i your life, perhaps, you’ve wanted to step out of the crowd of “listeners” and play yourself—gain good times, new friends and even fit yourself for increased income. But you have hesitated—wondering ifyou had talent. Now you can know — now is provided, by the Holton Talent-Test, a new free method by which thousands are proving they can play this easiest-to-learn of all saxophones — the Holton New Revelation. Persons who never dreamed they possessed the slightest musical ability have had this hidden gift revealed to them. Your request for booklet also brings you appointment card entitling you to Free Book theTalent-Testatany Holtondealer’s —tells how studio, or in your own home with Talent-Test the aid of a Holton Saxophone and is given our copyrighted phonograph record on which the Talent-Test is recorded. FRANK HOLTON & CO. Elkhorn, Wis. America’s Greatest Band Instruments Holton New Revelation SAXOPHONE /@@ ' { i ! 1 t { t ' , ! ! FRANK HOLTON & CO., Elkhorn, Wis. © Without obligation, I wish to determine my talent for the easy-to-learn Holton New Revelation Saxo- phone. (Check if interested in any other instrument): Cornet ( ) Trombone ( ) Baritone ( ) Trumpet ( ) Name

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FREE! Each Month— Live News of all the Latest Radio Developments ‘Radio Dispatch” is an entirely new type of radio publication. Itis person- ally edited by A. J. Haynes, Associ- ate Institute Radio Engineers. Each month it brings you complete infor- mation on new parts, new circuits, and new accessories, “Radio Dis- patch” is Mr. Haynes’ personal mes- sage to his friends who depend upon him to tell them about “What’s New in Radio?” “Radio Dispatch” is sent absolutely FREE to anyone in- terested in radio. Don’t miss the next number. Send in your name and address today. HAYNES-GRIFFIN RADIO SERVICE, Inc. Dept. S-2 250 W. 49th St., New York City 111 So. Clark St., Chicago

POPULAR SCIENCE MONTHLY

| You may depend on that. Henry Ford—‘‘There Is Always Room for More’”’ (Continued from page 149) airplane is coming, but it must find its place. What that place will be I shall not attempt to predict. “@(YERTAINLY the airplane will not displace the automobile, cause it to disappear, for nothing ever disappears. The automobile and the tractor have not brought about the disappearance of the horse, or of the bicycle. More people are riding horseback today than ever before, and the sale of bicycles keeps well within sight of the peak figures of 25 years ago. Despite the electric light, more candles are being consumed today than at any time in the past. The new thing never entirely displaces the old. When it ap- pears, it merely makes a readjustment necessary; then, when this is effected, with old and new occupying their places ot greatest utility, the world goes on much as before, though better, of course, for the improvement that has been made. “Everything finds its proper place in the world; every person, too, eventually. The automobile has been finding its place gradually for years. When the auto- mobile first came, the world was not quite prepared for it; there were few roads suited to the automobile, but the auto- mobile brought good roads, and it will bring more as they are needed. “Just now alarm is being expressed in some quarters because the automobile, in the necessary process of finding its place, is causing traffic congestion in our large cities. You frequently hear it said that the world is approaching the ‘satura- tion point’ in automobiles. The ‘satura- tion point,’ however—the time when the world will have more automobiles than it has room for—never will be reached. Just as the | roads needed by the automobile have been built, and continue to be built, so the | congestion that the automobile is causing

will be cured, not by double-decked streets, underground roads and cellar parking spaces in the business sections of the big cities, but by the elimination of the necessity for the present crowded business sections. ™ [RE automobile already has had its effect on the crowded centers of population. It has enabled people to move away from them into the country. It will enable—or even force—business to move into the country, too. When the owners of big stores find that people no longer are coming to them because con- gestion makes it impossible, they will move out where the people have gone— into the country. ‘People are becoming better educated from the automobile; they are becoming better acquainted with one another and more charitable toward one another. They are learning to avoid getting into trouble with one another. Some day it won’t be necessary for big buildings where people must go to see lawyers to get them out of trouble. They won’t have to go to the big buildings of the cities for other purposes either, for they will have (Continued on page 152)

The Ideal Rheostat for All Tubes The Marshall-stat provides a means of obtain; any desired tube adjustment with absolute Preci- sion. ‘The Marshall-stat varies the resistance, not step by step, but smoothly, continuously, and uninterruptedly from zero to maximum. The Marshall-stat provides vernier precision throughout its entire range. Yet there is only one knob to manipulate—no double adjustment to make. Besides its precision and ease of operation, the Marshall-stat requires only one hole in the panel, has only two terminals, can be used with any tube or combination of tubes, and is so scientifically constructed that breakage of the spec ially-treated Marshall discs is impos sible. Compact —note full-size cut above. Can be fitted anywhere. Price $1.75, MARSHALL ELECTRIS COMPANY 3241 Locust Blvd., St. Louis, Mo, Send for Old Man Ohm’s descrip- tive folder on the Marshalil-stat.

Make BIG MONEY! IN RADIO“ We Need Men—Can You Qualify? Ozarka representatives make real money be- cause they give real values and deliver a real service. For instance, there is a 4-tube Ozarka Instrument for loud speaker operation, giving wide range of reception at $39.50. Our men demonstrate Ozarka Instruments and Install. The Instrument makes the sale easy by its perfor- mance. We train you to know radio and our methods, make you worthy to wear the Ozarka button as our accredited representative. Previous experience is not necessary. In fact weprefer to doour own educating. If you have aclean record, are industrious, and have saved up a little cash, here’s a real opportunity, if ou can qualify for an exclusive territory. We alre: ave 2247 representatives. Territory going fast. Illustrated BOOK WRITE Today for illustrated \ book No. 101 that gives the entire Ozarka Plan. Don’t fail to give the name of your county. = \OZARKA, Inc. sae 856 Washington Blvd. CHICAGO g As Low $39°°

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

STANDARDS. See page 33.

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,taini @ preci istance, sly, and recision is only ustment ion, the ie panel, ith any itifically he spec s impos “size cut y where, CTRIS ui8 Mo, descrip- l-stat. e ’ fast. CGE OOK POPULAR SCIENCE MONTHLY TRADE MARKS-COPYRIGHTS PROTECT YOUR INVENTION _ ANY NEW aarticle, machine, design or improvement thereof, or any com- bination of parts or improvements in any known article which increases its efficiency or usefulness, may be patented, if it involves invention. If You Have Any New Ideas which you feel are useful, practical and novel, take prompt action to protect your rights. If you. have invented any new machine or new combination of parts or improvement, or any new design or process, SEND DRAWING, MODEL OR DESCRIPTION of it for information as to procedure to secure protection. > > . | hat oy F * ca. 2 4 ae DRAFTING and SPECIFICATION ROOM of CLARENCE A. O'BRIEN, Registered Patent Lawyer, Washington, D. C. > All communications are held in strict confidence. My personal, careful and thorough attention is given to each case. I offer you efficient, reliable and prompt service—based upon practical experience. Highest references. NO CHARGE FOR ABOVE INFORMATION Write today for free books, ‘‘How to Obtain a Patent’’ and “‘Inven- / | tion and Industry”’ and blank form ‘‘Record of Invention.”’ These books will give you valuable information, and they may save you much time and effort. Send for them now. My practice is devoted exclusively to United States and Foreign Patents and Trade Marks. Write me freely, frankly and with full confidence; it is very probable that I can help you. FREE These Books FREE Use the Coupon attached, and immediately upon its receipt I shall send you the form Record of Invention to be returned to me with drawing, description or model of your idea; promptly upon re- ceiving your idea I shall write you as to procedure and costs. CLARENCE A. O'BRIEN REGISTERED PATENT LAWYER Member of Bar of Court of Appeals, District of Columbia, United States Court of Claims; Supreme Court of United States, Supreme Court District of Columbia. PRACTICE CONFINED TO PATENTS, TRADE MARKS AND COPYRIGHTS --------------- FREE COU PON ---------------- CLARENCE A. O’BRIEN, REGISTERED PATENT LAWYER 889B Security Savings and Commercial Bank Building Directly across Street from Patent Office, Washington, D. C. Please send me your free books, ‘‘How to Obtain a Patent”’ and “‘Invention and Industry” and blank form, ‘*Record of Invention,”’ without any obligation on my part. EE aad Sl 5S) SL Re ann ON ns cen ne ge emer Cae Te ee ee Te IMPORTANT—WRITE OR PRINT NAME CLEARLY. © eee ee eee ewe ee eee ee esos IS) This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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POPULAR SCIENCE MONTHLY [Ss PATENTS— and Patents r is not unusual to find an in- ventor who believes that the degree of protection afforded by a patent depends upon the merit of the invention. Such is not the fact. The strength of a patent lies in the breadth of the claims that have been allowed by the Pat- ent Office. These in turn depend upon the care and skill with which they have been prepared and prosecuted by the patent attorney. Trademarks are even more val- uable than patents in many cases. It is essential that their registry be placed in expert hands, The standing of Munn & Co., identified with the publication of the ‘“‘Scientific American,’’ has been earned in a continuous practice of nearly eighty years before the Patent Office. The facilities and resources they have accumulated in that time are at the disposal of individuals and business houses at fees that are as moderate as conscientious service will allow. Write for Munn & Co.’s book on Patents. A succinct and accurate booklet of information on Patents, Designs, Trademarks, Foreign Patents, Copyrights, Labels and Patent Office Practice. It also de- scribes the methods and the terms of Munn & Co. 683 Woolworth Bldg., New York City 522 Scientific American Bldg. Washington, D.C. 411 Tower Bldg., Chicago, IIl. 364 Hobart Bldg., San Francisco, Cal. 219 Van Nuys Bldg., Los Angeles, Cal. Zl & & PATENTS Secured Trade Marks Registered Radio Inventions A Specialty Write Us Mason, Fenwick & LAWRENCE Patent and Trademark Lawyers Washington, D.C. New York Established over 60 Years References: National Confectioners’ Association, Chicago; National Canners’ Association, Washing- ton, D.C.; Life Savers, Inc., Port Chester, N. Y.; Bon Ami Co. and U.S. Cigar Co., New York City; Hershey Chocolate Co., Hershey, Pa.; Stephen F. Whitman & Son, Philadelphia, Pa., and many others. Chicago Henry Ford—‘‘There Is Always Room for More’’ (Continued from page 150) everything sufficient for their needs close by then in the country. Then there won’t be any big buildings, any crowded places at all.” ‘THs may seem like a fanciful theory. If you live in a large city, even if you merely work in a large city and commute to the country, you'll find it rather diffi- cult to imagine that city some day be- coming like its present suburbs. And yet Henry Ford sees this idea exemplified, partly anyway, in his own organization. More than 5000 automobiles, owned by Ford employees, are parked at the River Rouge plant every day, bearing eloquent testimony to the fact that men may motor to their work from as far as 25 miles away without inconvenience. About the Highland Park plant, six community, where store., shops, banks, theaters and schools make it unnecessary for Ford employees ever to visit the city itself unless they wish. The Ford plan of establishing small industries in rural sections where there are water-power sites already has proved the practicability of linking industry and the farm by sup- plying farm labor with gainful work be- tween the harvest and planting seasons. Henry Ford is reputed to be the world’s richest man, and the whole world, in consequence, has found its way to his door. You frequently hear it said that Henry Ford is not a philanthropist; that he has not followed the lead of other great industrial leaders in giving large sums to charity. Whether you look on him as a philanthropist depends entirely on how you define the word. He believes that the self-respecting man does not want gifts, but an opportunity to pay his own way; and that is the form that his philanthropy has taken. E PAYS the workers in his coalfields from 15 to 20 per cent more than the scale for miners. Noworker in his factories receives less than five dollars a day and that only during a 30-day period of training, after which he receives a mini- mum of six dollars and+is transferred from department to department, if neces- sary, until there is found for him a job at which he can make good. At the Henry Ford Trade School, boys, who because of educational defi- ciencies would be likely to remain common laborers, are given a chance to finish their schooling while they earn money and learn a trade. At the $8,000,000 Henry Ford Hospital the best avail- able medical and surgical treatment is offered to all who are ill at a flat rate. How much the average American workman has benefited through the wide- spread adoption of the once revolutionary Ford idea of paying the highest possible wages and carrying on an extensive pro- gram of welfare work it would be im- possible to estimate. Mr. Ford told me about another in- tensely practical form of philanthropy , (Continued on page 154) miles approximately from the center of Detroit, there has grown up an industrial | © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. February, 1925, 3 DIAMONDS. from Jason Weiler & Sons of Boston, Mass., one of America’s leading Diamond Import and Save 20 to 40% For over 48 years the house of Jason W of Boston, has been one of the Teadave” & Son importing concerns in America selling to e However, a large business is done direct {ovelers, with customers at importing prices! He mall several diamond offers—direct to you by mae which clearly demonstrate our position to name prices rest any present on diamonds that should surely inte or prospective diamond purchaser. 1 carat, $145.00 This one carat diamond is of excellent brilliancy. Mounted in Tiffany style 14K solid gold setting. Order this diamond, take it to any expert, make any comparisons you wish—if you are not en- tirely satisfied your mon- ey will be returned at once og a quibble. eon Tuite ng Bae ur ice di- i , ; sattord og a 3 $145.00 white g dj beautifully plereed ‘ol and carve A few weights and prices of other diamond rings: % carat, $31.00} 14 carat, $ 73.00 | 2 carats, $290.00 ¥% carat, 50.00 I-carat, 145.0013 carats, 435.00 We refer you as to our reliability to any bank or newspaper in Boston If desired, rings will be sent to any bank you may name or any Ex- press Co. with privilege of examination. Our diamond guarantee for full value for all time goes with every pur- chase. WRITE TODAY FOR THIS VALUABLE = CATALOG — FREE ON “HOW TO BUY DIAMONDS” This book is_beautifully (Ueda cells Lay to ; : judge, select an uy ? diamonds. Tells how | Write they mine, cut, and market diamonds. This book showing weights sizes, prices an goalies of a Million jollars’ worth of Dia- monds, is considered we : an authority. . iad Jason Weiler & Sons 372 Washington Street Boston, Mass, , Corner of Washington and Franklin Streets Diamond Importers since 1876 FOREIGN AGENCIES: Amsterdam, London and Paris > go END Fis roe) | DON’T LOSE YOUR RIGHTS TO PATENT PROTECTION Before disclosing your invention to anyone send for blank form ‘‘EVIDENCE OF CON- CEPTION”® to be signed and witnessed.. A sample form together with printed instructions i] will show youjust how to work up yourevi- i dence and establish thesame before filing ap- plication for patent. As registered patent at- torneys we represent hundreds of inventors al over the United States and Canada in thead- vancement of inventions. Our schedule of fees willbe found reasonable. ‘The form “Evidence of Conception,” sample, instructions relating to obtaining of patents and schedule of fees sent upon request. Ask for them,—a post A will do. PATENTS AND [ANCASTER Coe Registered Patent Attorneys 274 Ouray Bldg. WASHINGTON, D. C. Originators of forms “Evidence of Conception.” fe in U. S. and Canada \\ ri.

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ION to anyone OF CON- structions ) your evi- e filing ap- patent at- ventors all in thead- lule o f fees “Evidence s relating ile of fees New York Office Suite 1007 Woolworth Bldg. POPULAR SCIENCE MONTHLY TRADE-MARKS COPYRIGHTS OUR OFFER: Your first step ? Before disclosing an invention the inventor should write for our blank form ‘RECORD OF INVENTION.” This should be signed, witnessed ‘and returned to us together with model or sketch and description of the in- vention for examination and instructions. NO CHARGE FOR THE ABOVE INFORMATION Our Four Books Mailed Free to Inventors Our Illustrated Guide Book HOW TO OBTAIN A PATENT Full instructions regarding U. S. Patents. Our Methods, Terms, and too Mechanical Movements illustrated and described. OUR TRADE MARK BOOK Shows value and necessity of Trade Mark Protection. Information regarding Trade Marks and unfair competition in trade. OUR FOREIGN BOOK We have Direct Agencies in Foreign Countries, and secure Foreign Patents in shortest time and at lowest cost. AY Progress of Invention Description of World’s Most Pressing Problems by Leading Scientists and Inventors ALL COMMUNICATIONS AND DATA STRICTLY CONFIDENTIAL INTERFERENCE AND INFRINGEMENT SUITS PROSECUTED Philadelphia, Pa., Office Suite 714-715 Liberty Bldg. es | a” seas | Washington, D. C., Office Victor Bldg. Private Office, Victor J. Evans, with View of Patent Office Through Window T Highest References Prompt Attention Reasonable Terms VICTOR J. EVANS & CO., Patent Attorneys | | Main Offices: 760-9th Street, N. W,, Washington, D, C, : FREE 1 Gentlemen: Pleasesend me FREE OF CHARGE your | books as described above. MR MIDE eee oe ory races sia ati akaicoa cies ois WIM Oee ase eee ae 1 © tt LA CORA ET + ) NS Chicago, Ill., Office Suite 1114 Tacoma Bldg. San nasty Pittsburgh, Pa., Office Suite 514, Empire Bldg. ee ee San Francisco, Cal., Office Suite 1010 Hobart Bldg. © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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Why Many Men Are Old at 40 By Byram C. Kelly, A.M., L.L.D. Iam past 40 myself. I had begun to wonder when I would begin to break—to lose my old-time pep and aggressiveness—when through a mutual friend [ made the personal acquaintance of a certain member of the American Association for the Advancement of Science, whose wonderful work I had heard of. I made a trip to his laboratories and the things I learned should interest every man approaching or past the prime of life. Surprising as it may seem, nearly two- thirds of all men past a certain middle age suffer with a disorder of an important gland. Common Middle Age Ailments Here is an important cause for many con- ditions which heretofore have been taken for granted as old-age ailments—sciatica, aches in the back, legs and feet, frequent nightly risings, nervousness and _ irritability, and frequent dizzy spells, indicating high blood pressure. Constipation, headaches and depressed spirits often go along with it. But my visit would have been in vain had I not learned of an amazing treatment that relieves this trouble—a treatment that reaches this gland directly—and is so convenient that any- one can apply it in his own home. 100,000 Men Find Relief I know too plainly the effects of gland dis- order -when it is allowed to continue unabated. I know of the operations and the common saying among many that the average life after this opera- tion is only two or three years. That is why I am doing everything possible to let people know of this important discovery. Statesmen, bankers, lawyers, doctors, men from every walk in life have used the method with success. I have read hun- dreds of letters from gratified men. One I remember in particular was from a Colorado man which says: “73 years young is my age. Yet for years I suffered with this gland trouble. Used medicine to no avail—had about given up hope when a doctor recommended your treatment.” Just think of a man 73 years old restored to the health and buoy- ancy of youth—without drugs, electric rays or books. All Explained in Free Book If you have this trouble, if you suffer with any of the ailments mentioned above, you should not lose a day in finding out about this wonderful new method. Send immediately for an interesting, free book called, ‘“‘Why Many Men are Old at 40.” It describes this splendid treatment and shows you how you may regain much of your youthful vigor. Send your request to the Electro Thermal Com- pany, 4042 Main Street, Steubenville, Ohio, the concern that is distributing these books for the author. There is no obligation. If you are not interested yourself, you may be able to do an “older” friend an immeasurable benefit by showing him this article. Western Office: Dep. 40-G, 711 Van Nuys Bldg., Los Angeles, Calif. POPULAR SCIENCE MONTHLY Henry Ford—‘‘There Is Always Room for More’’ (Continued from page 152) he is about to institute. As a motor manufacturer he has learned that an efficient engine is produced only by use of the best materials, and is kept run- ning efficiently only by use of the best fuel and lubricating oil. He believes— and his opinion is substantiated by lead- ing scientists—that something similar may be true of the human engine. “VT BELIEVE,” he said, “that most hu- man ills are directly traceable to food. In manufacture you cannot make your product better than the materials you put into it, and food supplies the ma- terials from which the human body is built up. From proper food a strong body comes, from improper food a weak body. In epidemics some people become sick, others equally exposed, do not. The rea- son, I believe, is to be found in the differ- ences in physical constitution of the various people, due to the kind and quality of the food they are accustomed to eat. ‘Our organization is preparing to tackle this all-important food problem, and to solve it. In our laboratories we have the facilities to perform the necessary re- search, and through our organization we have the means of applying the knowl- edge gained in the laboratory and placing information on the food question where it is needed.” Despite the enormous demands that the mere routine of his position make upon him, Mr. Ford finds time to devote himself to a wide range of personal inter- ests. You read, no doubt, how he pur- chased, renovated and restored a pic- turesque old inn in New England. He is doing the same thing now to an old inn about 16 miles from Detroit. He is mak- ing a collection of old American music and musical instruments. He has a remarkable collection of old American carriages and other vehicles—the ‘‘one- hoss shay,” the mail coach, and so on. HESE, he believes, are the documents from which the present generation should learn of the past. That is what he meant when he said recently that history was “‘bunk.”” What he meant was history as written, colored, and ampli- fied by personal opinion and unfounded legends. It may interest you to know whom Henry Ford considers the world’s great- est scientists. These are the names he himself selected to be carved above the entrance to the new Experimental Labor- atory nearing completion at Dearborn, near Detroit: Darwin, Ampere, Da Vinci, Franklin, Fulton, Whitney, Bell, Marconi, Wright, Burbank, Edison, Burroughs (John Bur- roughs, naturalist), Kirby (Frank E. Kirby, naval architect, still living at Detroit), Diesel, Faraday, Curie, Otto, Newton, Dunlop (inventor of the pneu- matic tire), Pasteur, and Galileo. That probably would not be your list. I know it would not be mine. But it is Henry Ford’s—individual and character- istic, as is everything he does. February, 1925 @ Yes, only $3 down puts this enuine @ standard Shipman -Ward Rebuilt “Umiee § wood in your home. Then—small mon payments, or if convenient, pay cash, Either way you get the world’s standard typewriter at a big cash saving, WHY PAY RENTAL? Think of it! You pay little more than rental, and the machine is yours! We offer the same chree models of the Wnderwood writer which are being made and sold by the Underwood Company today. The only difference is that -W: machines are priced lower anc are rebuilt like new by experts. You can’t tell them from brand new machines. Visible writin, -—the FULL LINE of typewriting is visible at all times. STANDARD 4-ROW SINGLE SHIFT KEY- BOARD. Two color ribbon, back spacer, stencil de- vice, automatic ribbon reverse, tabulator, ete, TEN DAYS’ FREE TRIAL See for yourself! Try the typewriter ten days. You muct be satisfied or the entire trans- action won’t cost you a penny. Act today. Get log and full particulars, === FREE TRIAL COUPONea= ewriter Emporium SHIPMAN-WARD MFG.Q » 2142 Shipman Blde., CHICAGO ® Send by return mail Bargain Offer No. 2142, § ] of a Standard Visible Writing Underwood. H This is not an order and does not obligate ™ me to buy. i é : MMR EI RG rss sea ss in is fs a's f015 0 (G0 5 iar lee levee CREE a E § M Street orR.F.D.No.. 0.0.0.0... .cccceees | i Poatoffice......... i stete....o. en tk ae - Bete To the Man With an Idea } I offer a most comprehensive, ex- perienced, efficient service for his prompt, legal protection and the development of his proposition. Send sketch, or model and description, for advice as to cost, search through prior United States patents, etc. Pre- liminary advice gladly furnished with- out charge, My experience and familiarity with various arts, frequently enable me to accurately advise clients as to prob- able patentability before they go to any expense. Booklet of valuable information and form for properly disclosing your idea, free on request. Write today. RICHARD B. OWEN Patent Lawyer 6 Owen Building, Washington,D.C. 2276-D, 41 Park Row Cortland 0721 New York City © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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ary, 1925 February, 1925 Two-Cent Trails of Peril (Continued from page 53) and shelter. His frozen body was found py the roadside. For the first time in his long career he had failed to deliver the mails. Dreahn’s case may be taken as typical of the perils of the postal trail. A tragic companion picture is afforded by the fate of more than one carrier on the star route between Rocky Bar and Atlanta, in Idaho. The journey is made on snow- shoes, for no ordinary vehicle could com- plete the journey. Traveling afoot, the man with his 50-pound burden of mail is at the mercy of the storm. i THIS part of the Idaho mountains the avalanche is a frequent visitor, moving with a force from which there is no escape. Postal records show that a number of carriers have been buried in these monster slides. One of last year’s victims was missing for months. Half a year after his disappearance, the carrier’s body was found where he had been en- gulfed by the snow. His mail bag lay at his side. On the coast of Oregon there is a mail route that is made especially dangerous by the tides of the Pacific. Between Otter Rock and Newport this route follows the beach beneath a line of rugged cliffs. Carriers are supposed to traverse this stretch at low tide, but sometimes the carrier is caught by the rising tide. At such times he faces the danger of being dashed against the cliffs by the rush of waters, and can escape only by scaling the rocks. Many carriers have had nar- row escapes on this route. Utah has a mail route on which the winter problems are extremely marked. Heavy snows and deep drifts formerly made the mountain roads impassable for a good part of each year. Blockades of mail wagons were common. HIS condition prevailed until the in- troduction of the high-powered motor-truck. With this vehicle the Post Office Department has found it possible to buck the drifts and keep the route open throughout the winter. Expensive? Of course. This route, from Price to Vernal, is the costliest star route in the United States. To carry the mails between the two offices involves an annual outlay of something like $100,000. The distance is 121 miles. In a case of this kind, however, the government does not count the cost. The people of the isolated mountain regions are entitled to their mail as much as the city folk. On many of the star routes airplanes would seem to ofier solution of problems with which the postal authorities have fought from the beginning of the mail service. Winter air passage across the Rocky Mountains already is regarded as a foregone conclusion in connection with the air-mail between New York and San Francisco. Plans for this route contem- plate service every day in the year. Mountain storms and surface blizzards are to be disregarded. There seems to be no reason why similar defiance of the elements could not be practised on the shorter dangerous routes. POPULAR SCIENCE MONTHLY bigger quarters. realized. sharpened mower. W. F. Kendt, 1476 Main St., Buffalo, writes: I sharpened 994 lawn mowers last season, and the receipts were $1662 which is not bad for a side line position. pie 2°° Earned SEASON A NEW BUSINESS—BIG BUSINESS A Business to Enthuse Over— The “Ideal’’ Lawn Mower Sharpener A wonderful invention that sharpens lawn mowers scientific- ally—quickly—perfectly; does the work as nothing else can. Fred C. Milkert of Melrose Park, Ill., writes: “The Ideal Lawnmower Grinder put me in business, starting in the base- ment of my home and forcing me now for the third time to move into Today the dream of m With a machine like yours an have a business of his own and be independent.”’ You Start Now No town is too small. dull—owner doesn’t know where to get them sharpened. Mowing the lawn dreaded because of dull or improperly Lawn mowing is healthful, invigorating and please ' ant when Moweris ‘‘Ideally’’ sharpened. Youdo the work scientifically—you are in big demand. Lawn Mowers Sharpened to Razor Edge — People glad—owners delight in mowing lawn with mower sharpened on an “‘Ideal.’’ Mower runs light—click-click-click and the grass is cut. Build permanent business for yourself. Start now! Write Today gueaum Get our proposition Free We have detailed iillus- trated book to send you. Write today for our pro- 155 IN ONE life—a shop of my own—is . a little hustle any man can Lawn mowers are USE THIS — MAIL IT TODAY The Fate-Root-Heath Company 802 Bell St., Dept.39, Plymouth,0. Please mail at once details of your eomplete proposition. The Fate-Root-Heath Company Qe Miaretteressseessseecensecensersnneceensensen Dept.39, 802 Bell St., Plymouth, O. and With or without ex- perience, you can easily earn $75 to $100 a week taking orders for the famous FASHION WEAR shirts. Wear one of them and show to your friends. Every man a customer. Finest quality at low factory prices. Sales quick and easy. Some salesmen are earningas high as $175 a week. e send you Free complete sample outfit with wonderful swatches. You take the order. Wedeliver. START NOWand build a permanent, profitable and fascinating business of your own. Collect your profit in advanceand always have money. These remarkable shirts are selling amazingly fast, and sales are good all year round. We help you sell and give you a fair share on every shirt sold. If you really want the best money-making work anywhere write immediately for full information. Act before someone else grabs the rich territory that you can have. A post card will do. Address Charles Hope, THE FASHION WEAR CO. 1290-20 Jackson St., Dent. 72, Cincinnati. Ohio How to Build CGLTRADYNE MODEL L-2 32 page illustrated book with de- tailed instructions on drilling, wiring, assembling and operating Model L-2 Ultradyne Receiver. Latest authentic edition by R. E. Lacault, A.M.LR.E., inventor of the Ultradyne, the most selective _ receiver known. Write for descriptive circular. PHENIX RADIO CORP. 5-7-9 Beekman St., N. ¥. NVE our terms, methods, etc. your invention for our Instruc- tions. No Charge for the Above Information. RANDOLPH & CO. Dept. 130. Washington, D.C. PROTECT ITORS your iweas Send for our Guide Book, HOW TO GET A PATENT, and Evidence of Invention Blank, sent Free on request. Tells Send model or sketch and description of == - ER Ae Oe PES EO aE eS © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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EARLE E. LIEDERMAN The Muscle’ Builder AWart On Your Nose would not be noticed nearly as much as a frail, weak body. Yet, if you had a wart on your nose, you would worry yourself sick—you would pay most any price to get rid of it. But what about that body of yours? What are you doing to make people admire and respect you? Wake up! Come to your senses! Don’t you realize what a strong, robust body means to you? It makes no difference whether it be in the business or social world— everybody admires the strong, robust fellow— everyone despises the weakling. I Will Transform You I make weak men strong. That’s my job. That's why they call me ‘‘The Muscle Builder.”” I never fail. A bold statement, but true. I don’t care how weak you are, I can do the trick. The weaker you are, the more noticeable the results. I’ve been doing this for so many years, it’s easy now. how. In just thirty days, I’m going to put one full inch on those arms of yours. es, and two inches on your chest. But that’s nothing. I’ve only started. Now comes the real work. I’m going to broaden your shoulders and strengthen your back, I’m going to deepen your chest so that every breath will literally penetrate every cell of our lungs, feeding them with rich life-giving oxygen. ou will feel the thrill of life glowing throughout your entire system. I’m going to tighten up those muscles in and around your heart, kidneys and stomach. I’m going to shoot a quiver up your spine so that you will stretch out your big brawny arms and shout for bigger and harder tasks to do. Nothing will seem impossible. Sounds good, doesn’t it? You can bet your Sunday socks it’s good. It’s wonderful. And the best of it is, I don't just promise you these things—I guarantee them. Do you doubt me? Come on then and make me prove it. That’s what I like. Are you ready? Atta boy! I know Let’s go. Send for my new 64-page book “MUSCULAR DEVELOPMENT”’ It Is FREE It contains forty-three full page photographs of myself and some of the many prize-winning pupils I have trained. Many of these are leaders in their business professions today. I have not only given them a body to be proud of, but made them better doctors, lawyers, merchants, etc. Some of these came to me as pitiful weaklings, imploring me to help them. Look them over now and you will mar- vel at their present physiques. This book will prove an impetus and a real inspiration to you. It will thrill you through and through. All I ask is ten cents to cover the cost of wrapping and mailing and it is yours to keep. This will not obligate you at all, but for the sake of your future health and happiness, do not put it off. Send today— right now, before you turn this page. EARLE E. LIEDERMAN Dept. 1302 305 Broadway New York City EARLE E. LIEDERMAN Dept. 1302, 305 Broadway, New York City Dear Sir:—I enclose herewith 10 cents for which you are to send me without obligation on my part whatever a copy of your latest book, ‘‘Muscular Development.”’ (Please write or print plainly.) POPULAR SCIENCE MONTHLY

First Aid for Your Family (Continued from page 54) cold, and by its use sometimes one is en- abled to relieve the discomfort and to get a fair night’s sleep. In the use of drugs such as this, for the relief of headache and pain generally, it must be remembered that repeated doses at short intervals are unwise and even may be dangerous. For the treatment of skin inflammation caused by poison ivy or poison oak, some- times simple home remedies give relief. The best of these is a thorough scrubbing with kitchen soap and a soft brush and warm water, followed by the application of some soothing ointment such as zinc ointment or chloramine-T paste. HERE should be included in the medicine cabinet a harmless stimulant for the treatment of fainting not due to an organic cause, nervousness, or giddiness. Such a stimulant is aromatic spirits of ammonia. This may be inhaled as a quick stimulant or, diluted with water, it may be drunk for a more lasting effect. Where there are children and adoles- cents, nose-bleed and other slight external hemorrhages frequently occur and require home treatment. Bleeding from the nose usually may be stopped very effectively by the use of agents that produce a nor- mal clot. Such an agent is thromboplastin, prepared from tissues of animals that are

richest in the clot-promoting elements. A | pledget of sterile cotton or a piece of | gauze saturated in thromboplastin and placed in the nose in case of nosebleed, or into the cavity of an extracted tooth, will stop ordinary bleeding almost instantly. We have been hearing a lot in the past year or so about vitamines and how neces- sary it is that we should get a sufficient amount of them by a properly diversified diet; but the difficulty has been to get people to take a diet that is sufficiently | diversified and adequate to supply the needs of the body in this respect. This has been particularly the case with those vitamines called the ‘“‘fat soluble vitamines,”’ which are concerned with the normal growth of children, and the pre- , vention of rickets. HE two most concentrated sources of these vitamines are good butter and cod liver oil, but not emulsions of cod liver oil. The best cod liver oil con- tains more than 100 times more,fat soluble vitamines than does the best quality of creamery butter, and should therefore be included in every medicine cabinet of those homes where there are children. Regular courses of cod liver oil should be | given three or four times a year to insure

that the growing child receives the neces- | sary amount of the fat soluble vitamines. | There should be added a supply of a | good dental cream free from gritty abra- | cold | sives and with little or no soap; creams, zinc stearate, talcum and nursery powder for the baby; also a supply of sterile bandages and gauze of assorted sizes, and a good clinical thermometer. The householder should never lose sight of the important fact that the contents of the medicine cabinet are intended only for the relief of symptoms the severity of which apparently do not require the services of a physician. :

© This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. February, 1925 Squab Book FREE Squabs selling at highest prices e Greatest market for 20 years. Make mon breeding them. Raised in one month Ww ship everywhere our famous breeding stock and supplies. Established 24 year: Write now for big illustrated free bent How to Make Money Breeding Saueke? PLYMOUTH ROCK $ e "616 H St., Melrose meta ae FORD RUNS 57 MILES ON GALLON OF GASOLINE A new automatic and self-regulating devi invented by John A. Stransky, 4339 Fourth pe South Dakota, with which automobles have made fr 35 to.57 miles on a gallon of gasoline. It removes carbon and reduces spark plug trouble and overheating. It be installed by any one in five minutes. Mr. Strang! wants distributors and is willing to send a sample at own risk. Write him today.—Adv. Motorcycle Bargains SAVE 25% to 65% on Slightly Used and_ Rebuilt Motorcycles, Ace, Indian, Excelsior, Harley-Davidson, Cleveland, Side Cars, Johnson Motor Wheels, Evans Power Cycles, Bicycles. Send for : Free Bargain Bulletin and Hey: Money Saving Message, listin: Zz “ * hundreds of bargains in used, rebuilt and new machines, supplies, accessories, etc. RICAN MOTOR CYCLE CO. Dept. 228 2047 W. Chicago Ave. CHICAGO “LIGHTING FIXTURES” Ready to hang. Direct from the manufacturer. Completely wired including glassware. Send for Catalogue No. 26 (Just off the press) Special proposition to Dealers ERIE FIXTURE SUPPLY CO, Desk A. Erie. Pa. DEAFNESS IS MISERY I know because I was Deaf and had Head Noises for over 30 years. My invisible Anti septic Ear Drums restored my hearing and stopped Head Noises, and will do it for you, They are Tiny Megaphones. Cannot be seen when worn. Effective when Deafness is caused by Catarrh or by Perforated, Partially or Wholly Destroyed Natural Drums. Easy to put in, easy to take out. Are ‘‘Unseen Comforts.’ Inexe pensive. Write for Booklet and my sworn statement of how I recovered my hearing. A. 0. LEONARD, Suite 301, 70 5th Ave., New York Class Rings and Pins Largest Catalog Issued —FREE Samples loaned class officers. Prices $.20 to $8.00 each. No 4 order for class, society, club re emblems too large or too small. § Special designs made on re- * quest. METAL ARTS CO., Inc., 7706 South Ave., Rochester, N. ¥. a Aur IN YOUR HOME ¥ OF prc. Our marvellous, &

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You've heard your neighbor praise this wonderful weekly mage = —— ; = peopleread, Unl digest of national and world affairs. } full of just the kind of ee reading you want. <I ence, politics, travel, fun, fash’ os question box, books, health—entertainment and instruction for all. Send 15c (coin or sta! today for this big paper on trial 13 weeks or $1 for 1 year (52 issues). PATHFINDER, 559Langdon Sta., Washington, oD.

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ading lo. 26 lers CO, February, 1925 POHULAR SCIENCE MONTHLY 157 Here Are Correct Answers to Questions on Page 78 1. This is an effect of the hair cells going on strike. Instead of merely refusing to make color, they refuse to make hair at all. Poor nourishment is the most fre- quent: cause. Scalp massage or anything that stimulates the circulation of blood in the scalp will sometimes cure baldness provided the hair cells are not dead. 2. Very few, if any, of the chemical im- urities are removed by boiling. But foiling does kill the germs in the water. 3, Under ordinary conditions on the earth’s surface the lightest substance known is hydrogen gas. This is why hydrogen is used to fill balloons. The helium gas, which is now replacing hydro- gen for this purpose, is not quite so light as hydrogen, but possesses the great ad- vantage of being non-explosive. 4, Because the resistance of the air is reater. The snowflake is much less com- pact than the raindrop. The fi'ction of the air against it is therefore more easily able to counteract its weight. 5. Many of them have motions that we can measure by comparing their present place in the sky with their place several years ago. Others are shown by the spectroscope to be moving toward or away from the earth, this being detected by a change in the character of the light. 6. Light travels faster; it is the fastest thing in the universe. The speed of elec- tricity depends on what it is traveling in. It may go a good many thousand miles in a second, but it never reaches light’s speed of 186,000 miles a second. 7. No. The brain of an insect is not only much smaller than ours, but it is put together in a very different way. Many of the things that insects do are not con- trolled by the brain, but by little knots of nervous tissue in the body. 8. The radio waves are not waves in matter; they are waves in the ether, a medium that we believe fills all space even out to the most distant stars. The atoms of matter are quite open in struc- ture, with a great deal of space between the solid parts of them. The ether is sup- posed to penetrate into these spaces inside atoms. Accordingly the radio waves go right through the atoms of matter. 9. No. It used to be thought that certain foods, especially fish and other foods con- taining phosphorus, were especially valu- able for the gray matter of the brain. But it is known now that brain cells appar- ently use the same food materials as all other living cells. The best way to feed your brain well is to keep your body in good health. 10. A parrot happens to have a set of vocal cords and a formation of the throat capable of imitating many sounds, in- cluding human speech. There is no reason to believe that parrots ever un- derstand what they are saying. 11. Because it is all around us and inside of us as well as on top of us. When you hold out your hand, the air pressure on top of it is about three hundred pounds; but an equal pressure is being applied all the time to the under surface of your hand also. : 12. A geyser is a kind of hot spring. There is a long tube or tunnel that reaches down into the hot rock. Water accumulates in this tube and steam pressure begins to develop at its lower end. Finaily this steam pressure gets high enough to blow out all the water in the tube. his makes the geyser spout. The procedure is continuous. —— THEY SAY OF THE NEW SUPER-ZENITH: “Greater clarity and volume. Amplification is always at a maximum in each stage for any wave- length. Three stages audio frequency amplification.” Zenith amplifies with Thordarsons! THEY SAY OF THE KENNEDY: “‘The Kennedy tone quality is superb; full-rounded, musically pure reproduction of any program within a good long range. No hollow tones or distortion. For the Kennedy is a musical instrument. A musician will enjoy its purity of tone.’ Kennedy amplifies with Thordarsons! THEY SAY OF THE MURDOCK NEUTRODYNE: “To hear the real voice of the nation full and clear—you want volume. . . . Volume that floods your room,. . . Distant stations can be tuned in with remarkable clearness and volume.”’ Murdock amplifies with Thordarsons! is Superiority P ! gpa x uperiority Proved! SA NEY Note the emphasis placed upon tone quality in the advertis- Oper rt: dine high-grade radios. Pathe Is your present set disappointing? Buy a Thordarson- ing of the finest sets—the sets that have Thordarson am- ¢ ULTRADXNE equipped set—or replace your audio frequency transformers Leading makers are responding with sets embodying the best audio amplification. That is why more Thordarsons than all competitive transformers combined are now used in plification. People want radios that are musical instruments. with a pair of Thordarsons—or follow the lead of the leaders MURDOCK and build with Thordarsons. You will be delighted with the even volume they deliver over the entire musical range. MICHIGAN If your dealer is sold out, you may order from us by men- tioning his name. Interesting bulletins sent free. Write. alte C Go =~ THORDARSON | ELECTRIC MANUFACTURING CO. GzarKkh WORLDS OLDEST AND LARGEST EXCLUSIVE TRANSFORMER MAKERS THERMIODYNE Chicago, U.S.A. Ganstichl +> Unconditionally Guaranteed PHENIX é > DERESNADYNE | ' MALONE LEMON] GatEs* yuper po ll AMPLIFYING TRANSFORMERS ODELL F 2 ° e e PER TERY Standard on the majority of quality sets MASTER RADI TYPES AND PRICES: Thordarson ‘‘Super” Audio Frequency MUSIO io Transformers are now to be had in three ratios: 2-1, $5. 344-1, $4. 6-1, SAAL AND $4.50. Thordarson Power Amplitying Transformers are $13 the pair. MANY OTHERS © Thordarson Interstage Power Amplifying Transformer, $8. Write for latest hook-up bulletins—free! Earns Bis Money CAPE. X venient) J. Gordon Says $4000 Profit in 2 Months! Making and Selling | Popcorn Crispettes res Sa GEORGE ALEXANDER, of Pennsylvania, made $3,000.00 in 4 months. [ra Shook, Flint, took in $365.75 in one day. Bram bought one outfit, then 10 more within a year. Mrs. Lane, Pittsburg, sold 8000 packagesin ‘one a J. R. Bert, Ala., wrote, “only thing I ever bought that equaled advertisement.” Patillo, Ocala, writes: — “Crispettes all you claim andy then some.” Kellog, $700B ahead end of second week. ae} It Brings Em In! Get more stations—greater range—bigger vol- ume—finer selectivity—less interference. Lasts forever. The one big advance ict made in tuning. Ratio 12 to 1. Quickly applied to any shaft. For sale by all good Radio Dealers. If unable to ob- tain from dealer, enclose $2.50 for nickel-silver finish, or $3.50 for De Luxe satin finished gold. WE START YOU IN BUSINESS ! Furnish secret formulas, raw material, and equip- ment. Small capital required; noexperience needed. rere MPaTeETTa Build Busi f YourOwn SS uild Business of Yo ; Nolimit to the sale of Crispettes. Everybody likes 7-Tube Super-Heterodyne them. It’s a delicious food confection made withor | for $97.50 _ without sugar. Write for facts about a business that Reccive the parts complete to assemble your own set. hours. Parts complete, including drilled and engraved Send postal for illustrated book offacts Itcontains instructions. ‘Price of cabinet—to fit—on application. $7.59 and name of your dealer. information needed. Free. Write now! IS) This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. é “i ‘e i Microdyne super-heterodyne cn a 7x18 in. panel in three Profit $1000 Month Easi ly Possib e necting plugs, cables, etc., with drawings, diagrams and of business, tells how _and when to start, and all siicrodyne Radio Het, ecnd check oF money order for 1410 W. 59th Street, cHICAce will make you i ndependent. Start in your town. Coast |o coast on an 18-inch Loop. Assemble this 7-tube panels, condensers, sockets, transformers, dials con- enthusiastic letters from others—shows their places If your radio dealer cannot supply parts for complete APEX ELECTRIC MFG. CO. Dept Long-Eakins Co. 247 High St. Springfield, O.

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¥ } *

¥ te | i ; pm sees POPULAR SCIENCE MONTHLY February, 1925

7 for many reasons. . for set screw assembly. © Nine out of ten sets use MICADONS! Nine out of every ten sets made use Micadons—the standard fixed radio condenser. They know that the Micadon is a Dubilier product, hence supreme in quality and efficiency. They know that Micadons can be obtained in accurately matched capacities and that the capacity is permanent. They know that Micadons are easily installed, equipped as they are with extension tabs for soldering and eyelets They know that Micadons are made with type variations to meet every possible requirement. For the best results use MICADONS. Dubuilier

Set builders choose them

CONDENSER AND RADIO CORPORATION

_%

Position with the - U. S. Government Thousands of appointments are made yearly. Good salaries—short hours—liberal vacations (as much as 30 days in some branches of the service). Positions open now in Washington and in other cities. “Pull” and influence unneces- sary. Common school education sufficient as groundwork for most positions. The International Correspondence Schools will pre- pare you right at home to pass your Civil Service examination with a high mark. Mail the coupon today for 48-page Free Civil Service booklet. INTERNATIONAL CORRESPONDENCE SCHOOLS Box 7639-D,. Scranton, Penna. Without cost or obligation, please send me a copy of your 48-page CIVIL SERVICE BOOKLET, which tells how I can secure a good-paying posi- tion with the U, 8. Government.

clean intense to $75 a Day Man Alive— | Look What You’re Missing! Oliver men are cleaning up. Making $25 to $75 a day! It’s the chance of a litetime. Don't lose another minute. Write. Big season now on. Learn how easily Olivor Oil-Gas Burners sell. Amazing invention. burns Oil, mixed with air. Better heat than coal or wood. Fits into fire box of range or heater. Models for all types of fur- naces, too. 12 models in all. Appeals instantly. Turns any range into a gas stove. Wonderful, glowing heat, at the turn of a valve. A few minutes’ demonstration makes the sale. Yes Sir, It Sells Itself! ACT NOW! Every woman wants one the minute she sees it. Every buyer recommends it. Means more sales for you! The Oliver is a winner. Greatest burner ever. Saves women the drudgery of shoveling and carrying coal, building fires, scraping out ashes. Keeps furnishings clean. Priced within everyone's reach. Saves its cost a hundred times over. Can you think of anyone wanting to be without it? OLIVER @ks BURNER GAS You don’t need to be a high-powered salesman. Sell only one Burner a day and you’ve made $75 a week. Think of it! And we guarantee your first sale. Over 200,000 already sold. Get our Free Sample Case offer. OLIVER OIL BURNER CORPORATION Manufacturers of Oliver Oil-Gas Burner Products 259 OLIVER BLDG. ST. LOUIS, MO. Oldest and Largest Manufacturers of Oil-Gas Burners in the World © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. Can You Pass These Tests? (Continued from page 45) 867314 739548 382145 672539 378659 963458 371629 596743 784623 35847) 345962 294736 198537 916483 635819 672389 389254 259671 123874 320418 312876 427395 561487 593182 247153 934612 759431 281937 461289 57936) 954178 718254 296851 524617 731825 719325 486592 215367 714529 95614) 594231 156843 436978 851763 513647 349716 182653 286415 164985 768914 714932 427163 825749 983567 682917 649752 587436 268794 179428 145389 462758 843216 853624 985273 67284] 981374 529817 862934 875126 319546 941258 639187 871596 294378 237465 346521 196235 762491 957641 495867 853926 138962 435781 297568

Solution to test in Fig. 1, page 45: How the blocks fit in the arrow. The answer to Fig. 2 is to remove the three matches within the largest triangle, leaving two triangles How rapidly do you learn? Below isa simple code, in which each letter of the alphabet is represented by a number. The word “‘and”’ would be written 2-13-10, In this test you are to write the code number for each letter just above it, as fast as you can while some one times you. A college student can translate 90 letters into numbers in five minutes. CODE jd tt gg en hwo rx 9 10 11 12 13 14 15 16 17 ¢ m b &k i f o b ec 18 19 20 21 22 23 24 25 26 Translate these letters into their cor- responding numbers: -Paethette_seseres €°3 fogathosdan ¢s emgith tah tohs@ haheedgde@eronihtoa’?d foterononwcecemace @rniowdoponu sh ircrneocoiteile t& tm iwoge h«ert ¢ ae a keorhoet ses <& meocot s @repecnias osykdandigrwna If you can pass these tests, you have mental capacity to spare for most of life’s activities. Remember, too, that those who make the most of their ability are the hardest workers. So work hard with your abili-

; Febru Yo Pra on |

ties if you would be successful.

Page 127

1925 ; February, POPULAR SCIENCE MONTHLY fyour Dials—Keys to the Air (Continued from page 84) Practically all of them, however, operate Why it is Better 3 on a loop aerial, consequently it is neces- 19 sary to follow the instructions for placing Thumb nuts slotted for screw 18 the loop that I outlined under reflex sets. rc 1s ee 53 This should be done before hunting for = 61 the station. ig 25 The majority of super-heterodyne re- . ii alain - . 2 inc iC) rass nicke 2 indir “ ceivers have two large tuning dials on the plated barrel, screw-anchored One pice binding ost molded 4 panel. There are some trick ‘‘supers, to base at two points thumb-nut is tightened, 17 but since they are invariably constructed . 89 by men who have a full knowledge of the Full 9/16 inch thick, 2 1/4” 41 theory and practice of radio, it is unneces- REIS ee P z é h hosphor bi : 46 sary to describe their operation here. peerings Ay 00 : 65 They are the exception and do not come basé positively prevent short f:: 67 into general use. On the standard sets the first dial is for tuning to the wave length of the station desired. The second dial controls the frequency-changing de- vice that enables the system to operate with full amplification. N TUNING a “super” it is important to move the dials very slowly, other- wise it is quite possible to pass over the proper settings. In fact, a Vernier ad- justment, or a geared dial is practically necessary. It will be found that after a station is brought in and the first dial is circuits of radio frequency 3 leakage. RSs Mounting screws are furnished with each socket. Contact for grounding socket can be made =A, under heads of these screws. Tue picture tells the story — seven This screw holds only the cone tact spring securely in place, not extending through to top of base —an exclusive Federah, feature. BS t making Federal Standard Radio Parts. a left in its position, the second dial can be practical, sensible Soneeee: wey There are over 130 standard parts he IN ein duntd it Serlame i tho snare Federal sockets should be in your bearing the Federal iron-clad per- T. station at another position. Each of pet hook-up. Federal socketsarebut formance guarantee—their use means 0. these two positions should be noted, and another evidence of the care anden- —“Balanced Circuits” with better de the one that gives best results used. gineering skill used in designing and _ performance. as On the second harmonic super-hetero- FE TEL uu. dyne there are three, and in some cases DERAL LELEPHONE AND TELEGRAPH Co, TS four, points where the same station can be Buffalo, N. Y. © tuned in. It is best to log these settings on a card, and try them when looking for the same station again in the future. If om Chi ‘ ; : cago interference is experienced at any of the New York settings on the second dial, go to one of Philadelphia San Francisco x the other points where the station can be ; ‘ ; , : Bridgeburg 17 heard, and see if the interference still ex- | Pittsbureh Standard Products Canada ists. When noise is experienced while peers meena % listening to a distant station, try reducing / the rheostat dials. yr- After you get a station with the super- heterodyne or reflex set, make a final slight adjustment in the position of the | [iy 7-pe 7 /-/, (z i loop aerial. It will be found sometimes Not 1h - ar von pemeect™ that although the loop is pointed directly Of ar Ol Durner mua vea 8 toward the transmitting station, maxi- | 4? @ scientific pray? mum signals are not obtained. The rea- method of RR oe son may be a local one. Some mass of burning coal n metal may be reflecting or refracting the waves, and thus cause a slight variation c in the position of the loop.. These little U. S. Tool Feature knacks of tuning can be mastered after a This i rer iin h iis” aetetian ok sme anh 113 inexpensive coal-saver and heat 0 Pi p : producer is a positively safe invest- hneriece Stator h ment paying extraordinary dividends (Pat. Applied for) in money and comfort. Found in no other make, ; the one piece stator makes Science of Cross-Words Why pay out any more than 100% efficient. Bitmi * ° mi- t you have to for coal? nates leakage, resistance, F THE cross-word-puzzle ‘ oe cece — pl Crown dered ices ia Ge s ° ‘uel Saver to your heating plant you (plain) and 4 (all-vernier) . bug has bitten you, don’t can burn feat iat pat yp ish Celoron End Plates; t miss the March issue of POP- 20% anda agentes Moo saving of at least be (lei) amt — y or your money back on demand. The ple ° P Fe ULAR SCIENCE MONTHLY. You Crown offers ay pe quicker heat, steadier the Metal ake . ; j neat, less firing, less ashes, less expense. . vewri s will find a fascinating story of The Crown fits the feed, p vena of aio heating CS and CV low p ice the fad that has swept the en- plant—steam, hot water, or warm air. Fur- types always 1n stock. : : nishes by natura raft pre-heated air to Vd tire country with such sensa-~ burn smoke and gases a wasted. (See ASK YOUR DEALER! eS tional popularity, and—an en- papas groan he Song sg ae 100% GUARANTEED - iu to get out of order. Lasts a lifetime. Install it c ke tirely new kind of puzzle to yourself. In successful use 10 years in homes, Write for Literature - intrigue your interest. fdlinformation, |_| U. S. TOOL COMPANY, INC. on ° echanic St. ewark, N. J. li- Crown Fuel Saver Co., 12 N. 10th St., Richmond, Ind. Mie. of Seustes Tools, Dies, Jigs, DISTRIBUTORS WANTED. Write for our profitable business building plan. - Automatic Machinery and Sub Presses. © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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160 opularity Yfours-with this mos winning of all musical Instruments You can be popular - you can be in demand socially - you can be welcome everywhere - with an SCH: ESC elaitiene Don’t be a wall-flower. Don’t beadawdler. Step out of the crowd and into the picture. Be able to do some- thing to earn your welcome. Learn to play a Buescher Saxo- one. Easy to Play Easy to Pay You'll be astonished how uick you master this beautiful in- strument. It’s not necessary to be talented-to be musically inclined. The Buescher Sax- aoe 4 is so perfected and simplified that practically anyone can learn to play. The scale can be mastered in an hour; in a few weeks you will be playing popular airs. Practice is pleasure, because you learn soquickly. 6 days trial and easy payments. Free Send coupon or postal for a copy of our latest Saxop od Book. Tells all about the various Buescher Saxophones, with pic- tures of the farnous professionals and orchestras. Mention any other instrument in which you may be interested. 167 Sc a BAND INSTRUMENT Co. Everything in Band and Orchestra Instruments 428 Buescher Block Elkhart, Ind. | Buescher Band Instrument Co. ‘ 428 Buescher Block, Eikhart, Ind. | | Gentlemen: \ I am interested in the instrument checked below: | | Saxophone...Cornet...Trombone...Trumpet... | (Mention any other instrument interested in) { et Bh ens ws ong pom eee | { EE i koa Woe hss ehebwtea I hae a POPULAR SCIENCE MONTHLY To Do Good Soldering (Continued from page 85) solder on the end of the copper touches the joint. Hold it in this position until the solder flows into the joint and over the ends of the wires, as shown in Fig. 3. Then re- move the copper and hold the wires steady until the solder has cooled and hardened. Many beginners’ experience trouble through failure to hold the wires steady. The slightest motion at the instant when the solder hardens will result in a weak joint. i THE copper is too cold, the solder will not flow over the joint and the wire ends, and if it leaves the copper at all, it will form in little gobs or drops that often can be rubbed off the wire with the fingers. The whole secret of soldering is to get the solder to flow on the wires like oil on a steel surface and not like drops of mercury on a glass plate. In Fig. 4 are shown a number of soldered joints. At the left is an example of how not to do it. Note how the solder has failed to run on the surface of the metal. The second example is the joint that was actually made while the photo- graphs used in Figs. 2 and 3 were being taken. The third and fourth show how the wires should be overlapped if there is to be any strain on them. After you have the hang of it, you will find that it takes much less time to wire a receiving set by soldering all the connec- tions than it does if you have to carefully form a loop at each end of every wire to clamp under the binding posts of the in- struments. Also, it is easier to cut and bend the wires to the exact Jength when you do not have to allow for the bending of the loops. If you use the rosin core solder, you need not worry about the excess soldering flux, since rosin is a good insulator itself and has no tendency: to creep over the surface and collect dust. When the greasy types of soldering pastes are used, it is well to use as little paste as possible and wipe off the joint the wires are still hot. If this is done, between rosin and the usual pastes except in soldering the standard types of jacks that use fiber strips between the contact fingers. T SEEMS to be almost impossible to solder these jacks with ordinary solder- ing paste without having some of the paste run up the lugs and soak into the fiber. and in many leakage losses. Do not be afraid to tackle soldering. Ten minutes’ practice will teach you the knack of it and after that you will wonder why you thought it was so hard! cases actually causes aff OW to build a two-tube radio set that will produce plenty of loud- speaker volume without distortion will be described in an article next month— This is a truly remarkable radio set, nevertheless one that you will find very easy to construct. carefully with a rag after each joint while | This makes a messy looking job | there is no choice in electrical efficiency | February, 1925 CUNNINGHAM AMPLIFIER TuBE "PEC 3018 Reception 5) RADIO experience and resources of the great General Electric Laboratories in every socket of your receiving set. Since 1915—Standard for all Sets types C-301A, place the skill, C-299, C-300, C-11, C-12. In the Orange Blue Carton. Price ‘$4. 00 each. Patent Notice: Cunningham tubes are covered By fpems dated 2-18-U8, 2-18-12, 12-30-13, 10-23-17, 10-23-17, and others issued and pending. Cunningham 40-page data book fully explaining care and operation of Radio Tubes now available by sending 10c in wa to San Francisco Office. NEW YORK HOME OFFICE SAN FRANCISCO CHICAGO used in playing @ the fascinating Hawaiian Gui- Co me tar. Our native & Hawaiian instruc- tors teach you to master them uickly, Pictures show how. Everything explained clearly, PLAY IN HALF HOUR After you get the 4 easy mo- tions, you can play harmonious chords with very little practice. 40,000 students have !earned to play i in this easy, pleasant way. EASY LESSONS The 82 printed:lessons with a great many pictures Hea it easy to learn quickly, You don't have to know how to read notes. No previous mus: ical knowledge necessary. learn to play any kind of music, and pay as you play. EE GUITAR As a special offer to new students we give this full size, high grade in- strument free of charge. It is sent baa\g at once without red tape or delay. if WRITE AT ONCE our name at once and let us and the _— guitar. thing to gain. Don't put it o post card will do. Ask for new Bpe- cial offer and easy terms. First Hawaiian Conservatory: of Music, Inc. we; 233 Broadway (Woolworth Bldg. pt, 46, New York, N.Y Special courses on Vio- lin, Tenor-Banjo, Ban- jo-Ukulele and Ukulele De! PATENTS BOOKLET FREE HIGHEST REFERENCES PROMPTNESS ASSURED BEST RESULTS Send drawing or model for examination and report as to patentability WATSON E. COLEMAN, Patent Lawyer 644 G Street N. W., Washington, D. C. © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. ee UATE LTT CUTE EEUP AEDS CET AOS AADOREUMCCUUMAUCUATO SOL ECCCEOCULEAMUE ERLE EAMG EEUUUEUUEOUULOSAEOLEG RUC ASONNUOSAGEEDTUOUEUALEUATEEUUUUUTEEREURRT ERT LUUREUUEUULELL REUTER ELLE Ts teers i. ee ae. ee) ee Ae UT

Page 129

yer

_-pebruary, 1925

POPULAR SCIENCE MONTHLY

VAL ZZ IITA TTT Sa A,

* i | *UTAKH Made In Sait Lake City $250 Phono-Speaker $10.00

TETTUTTTTTUTU TTP Cesc ee tern CQU KURO LQ OTTOCUTDPUT TT DCCIUUUERORLLULELALURLORCULALOLRRLOLLRLCU MASUR OL ec ict

i = — — a = — 7 = — =a a — — — — — — — — —) — = — = —) = — a— — — — — = — — — — —) — — fo ~ D Sigg eS ~ -? fe ~ te * pr ee Me > fe nA Con Q 4 LL ATK cM A MAMTA Ma Radio Music as You Ne OW! Never Heard it Before OU never heard such tone! You cannot guess the won- derful musical possibilities of radio reception until you hear UTAH reproduction. 5)

Hear It! Rich, mellow, natural tones of instrumental music—the deli- Go wen tested cate shadings of the human voice—satisfactory volume from er’s store and ask for a a weak and distant station—or big volume from a strong marr pag ms station, without the rasping and blasting that big volume has with you and enjoy it for always caused—that’s UTAH reproduction! pte nt ry = The new UTAH speaker is the latest triumph of acoustical and electrical engineering—the result of two years work by the leading experts in sound reproduction. © UTAH Radio Products Co., 1427 Michigan Ave., Chicago © This séal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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162 POPULAR SCIENCE MONTHLY

that is saying a great deal. TRONS occupy a front rank position among vacuum tubes; they know no su- . periors and very, very few equals. both internally and externally. are now manufactured in the tipless form. This is an important feature; it greatly re- eg the chances of accidental breakage. e Pure bakelite is used, thereby cutting down leakage and capacity.

AGNATRONS today are better tubes than they ever were before—and MAGNA- MAGNATRONS have been’ changed All types bases, too, have been improved. The internal changes in MAGNATRONS make these tubes more fitted than ever for efficient radio frequency amplification and powerful audio frequency amplifica- tion without distortion. self on this point by hooking a MAGNA- TRON into the circuit. Convince your- MAGNATRONSare madein three types— the DC-201A, the DC-199 with the miniature base, and the DC-199 with the large stand- ard base. fre $4 ©

dex MAGNATRONS

CONNEWEY ELECTRIC LABORATORIES 309 Fifth Avenue NEW YORK CITY alice —fo-

CITY SALESMEN advancement. Wecan protably place you in your own town. The new Corona Four, just out, is the greatesttypewriter value ever offered. wonderful chance for the rightman. Experi- . —- Phase Angle Difference ispedance) So ~~

in which this remarkable 100 200 300 400 500 600 coil can be used. : Wave Length (Meters) UNCLE SAM ELECTRIC CO. 299 East Sixth St., Plainfield, N. J.

Tried by a thousand trails

(CARLETON CANOES are built to stand the gaff of years of the hardest service. They do it too. In over a quarter of a century of manu- facture we have never had one dis- satisfied user. Carleton Canoes are wonderfully light. They are beautifully balanced, fast and surprisingly easy to handle. And Carleton Canoes are unusually reasonable in price. Send for our new illustrated catalog. It gives prices and complete informa- tion. Write for your free copy today. Tue Carieton Canor Co., 72 First Street, Old Town, Maine, U.S. A. jc

| the sub-panel T is fastened to them by | between the solder lugs of jacks P1 and rae Four-Tube Set to Fit Your Phonograph Cabinet (Continued from page 87) screws. Next, mark each hole deep} with a prick punch and drill the holes a size to fit the shafts or screws that are ty go through them. When the holes arp drilled, wash off the paper and try mount. ing each instrument to make gure that the holes are correct. Take Particular care to have the holes for the jacks Pl P2, and Q in exact line horizontally, tie means of No. 8-32 brass screws. ‘THE simplest way to fit the sub-pangl T is to drill the holes and tap them in the frames of the jacks first, then bolt the jacks to the panel, lay a piece of Paper on the bottom of them, and mark where the holes come. You then can use this paper as a templet to show where to drill the holes in the sub-panel. The serew holes in the frames of the jacks should he about one inch from the ends that are fastened against panel S. Next, bolt the sub-panel 7 on and arrange the amplifier sockets, J2, J3 and J4, the audio transformer J and the by- pass condenser G, as shown in Figs. 4, 7, and 8. No layout can be given for these instruments because of the variation in size and location of mounting screw holes, binding posts, ete. The sockets should be placed near enough so that the coupling condensers H1 and H2 can be soldered directly to the plate and grid binding posts. The sockets should be placed so that the filament binding posts are farthest from panel §. Now mark off on the sub-panel T the loca- tions of the holes for the screws to hold the instruments in place and for the bind- ing posts Nos. 1 to 7. In addition, there should be a small hole for the connecting wire near each socket filament binding post; one each under rheostats K2, K3, and K4; one for the wire to switch R1; one under the plus B terminal of transformer J; one midway P2; and two near by-pass condenser G. The fitting of the detector-tube socket panel U comes next. It is held in place by a No. 8-32 brass screw that clamps it to the .two brass angle brackets. These are held against the panel S under rheostat K1, and switch R2 is set so that the ends come together. The socket J1 is fastened to the sub-panel U by brass screws with the grid and plate terminals toward tun- ing unit A, B, and C. Now assemble all the instruments as shown in the illustrations. This com- pletes the construction work. HOW TO DO THE WIRING It is well to do all the filament and A and B battery wiring first to cut down the chances of an error that might result in burning out the tubes. : From binding post No. 2 run a Wile under the sub-panel to the hole uncer switch R1, up through the hole to one terminal of the switch R1. Cover this wire with spaghetti below the sub-panel and above it past rheostat K2 (see Figs. 2 and 8). Now connect the terminals of February, 1935 “4

Februar Fou I the sw Figs. : switch rheost: filame! connec switch connec R3 to The should hand t the ree mainin kand F termin of socl coverir under tubing. Fron coveret remain and rv the re sockets nearest and to about t the mi battery sockets and mi nothing sockets RET? EX un No. 6 | former. tom sol the top run a §s the hole No. 7. reverse the pol: loudspe three je Pi and the tip circuit s tacts wi Now : the plat in place to the Bend uy place se sprung ‘| After t] coupling the plat J2, J8, pair of . that th capacity isa sligl musical Next, between Plate te same so) and sock

(Continued on page 163) ——==

© This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

Page 131

1925 4 ply of a e to are unt- that ular Pi, for by anel hem bolt aper here this drill crew id be ; are and } and e by- 4, 4, these on in holes, near nsers to the ckets iment nel §. » loca- » hold bind- small - each 2 each ne for e plus idway 1 and ser G. socket place 98 it to se are eostat e ends stened s with d tun- nts as ; com- G and A wn the sult in under to one er this p-panel e Figs. inals of - pebruary, 1929 Four-Tube Set to Fit Your Phonograph Cabinet (Continued from page 162) the switches Fl, R2, and R3 as shown in Figs. 2 and 4. From the wire between switches R1 and R2 run branches to rheostats K1 and K2 and to the minus filament terminal of transformer I. Now connect a branch from the wire between switches R2 and R38 to rheostat K3. Next, connect the remaining terminal of switch R3 to rheostat K4. The other terminal of rheostat K1 should be connected with the nearest left- hand terminal of socket J1 (as seen from the rear in Fig. 4). Now connect the re- maining terminals of rheostats K2, K3, hand K4 with the nearest right-hand terminals (as seen from the rear in Fig. 4) of sockets J2, J3, and J4 respectively, covering the portion of the wire that is under the sub-panel U with spaghetti tubing. From binding post No.4 runaspaghetti- covered wire under the sub-panel to the remaining filament terminal of socket J2 and run spaghetti-covered branches to the remaining filament terminals of sockets J1, J3, and J4, to the terminal nearest panel S on by-pass condenser G, and to binding post No. 5. Do not worry about the fact that you will be connecting the minus battery terminal of the A battery with the plus terminals of the sockets, and vice versa, because the plus and minus markings on the sockets mean nothing anyway, and on many makes of sockets both terminals are simply marked oD.” ot: run a spaghetti-covered wire under the sub-panel from binding post No. 6 to the plus B terminal of trans- former J. Now run a wire across the bot- tom solder lugs of jacks Pl and P2 and the top lug of jack Q, and from this wire run a spaghetti-covered branch through the hole in the sub-panel to binding post No. 7. The terminals of the jack Q are reversed in this fashion in order to keep the polarity of the current through the loudspeaker or phones the same in all three jacks. In the closed-circuit jacks Pl and P2, the bottom lug contacts with the tip of the plug, while in the open- circuit style of jack (Q) the top lug con- tacts with it. Now study Fig. 6 carefully and see how the plate resistances O1 and O2 are held in place by means of wire clips soldered to the center lugs of jacks Pl and P2. Bend up the wire clips and solder them in place so that the resistances may be sprung into them as shown in Fig. 6. ‘| After this is done, you can solder the coupling condensers H1 and H2 between the plate and grid terminals of sockets J2, J8, and J4 as shown in Fig. 6. Each pair of .006 fixed condensers is placed so that the solder lugs are together. A: capacity of .012 instead of the usual .006 isa slight advantage in passing the lowest musical notes. Next, connect a short piece of wire between the top lug of jack P1 and the Plate terminal of socket J2. Make the Same sort of connection between jack P2 and socket J3, and then connect the lower (Continued on page 164) POPULAR SCIENCE MONTHLY 163 — es MURDOCK NEUTRODYNE Announcing» The new Murdock 5-tube Neutrodyne with “built-in” Loud Speaker and “B” battery compart- ment—backed by 20 years experi- ence in making fine Radio Products, NOTICE IJ F your dealer doesn’t sell Murdock Pro- ducts write for beautifully illus- trated booklets giving complete description of all Murdock Products. worms snteg Licensed by e- ier: Redio menutecrro am 3 oa. eros 130.000 ory ag) Petents = Arn ee oer Pending “0 WM. J. MURDOCK COMPANY, 430 Washington Ave., Chelsea, Mass, Sales Offices: New York, Chicago, San Francisco, Washington, D. C. ° MURDOCK RADIO PRODUCTS Standard since 1904 $25.00 in PRIZE See top of page 10 in front of book for details GNTED Men and Women Housewives all over the country want Stuart’ —the original—non-alcoholic food flavors an colors in tubes, toilet articles and kitchen specialties. The only way they can get them is through our agents, who easily ep A STUART, C. W. BAcK, Mich., says he sold $52 worth in two days; Mrs. Bus, Iowa, got $10 worth of orders over the phone in four hours. You can do it with our plan. No experience needed, Write at once for details, Cc. H. STUART & CO. 6 668 Lake St. Newark, New York [rio A (>... 1S] This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. Protect Your Tools with- NYOUL, Your valuable tools can be protected absolutely from rust. Cover all your tools that you aren’t using regularly with a thin coat of NYOIL. Keep a can in your tool chest. The patented cap prevents it from leaking. Remember—Summer is the worst season for rust um. Makes an excellent polish or pianos, automobile an other highly finished surfaces. Buy Nyoil of your dealer or write us. W. F. NYE, New Bedford, Mass.

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we) (() $I XS SOCY, _ oe an NOY eR Kom on Fd ON ~ POON eR ae LX NON SO eR S5:e5 . POCYYOCKS ws Ideal Tone ; Reproduction? i ! o> othe factors influence radio tone quality between the an- tenna and the horn—valve-action in the vacuum tube, the design of audio transformers, electromagnetic action in the loudspeaker unit. Absolute perfection in any one factor is of no avail unless the other factors are equally perfect. Famous experts in audiotransformer design, when released entirely from cost limitations, are thus able to pro- duce an instrument which, by com- pensating for imperfections in loud- speaker efficiency, produces results far superior musically to the “‘theo- retically perfect” amplification of re- sistance coupling. At the same time, we retain the high amplification pos- sible only with transformer coupling. e Detailed description of this Laboratory- Grade instrument, with amplifi- cation curve, on request. Rauland Mfg. Co., 2668 Coyne St., Chicago. Price $9.00 Ask Your Dealer TRANSFORMER The Choice of the Noted Music Critics ae KK— Seu) OSY RR % AA “ MODPYOCKSSS OOKK De, SONS wR mM Re en $, ms WOOSY ar RvR mee (SSE RR % Ay OXY py SK mS OSENRAOOY eR % S OoY POOCYS A x Ramm am # ~~ eR on ek OOSYy ee SONIDO a OO LN XY OOS 7 mm LOOKS RR CORLL POPULAR SCIENCE MONTHLY TERROEXKROSS A Four-Tube Set to Fit Your Phonograph Cabinet (Continued from page 163) lug of jack Q with the plate terminal of socket J4. Look at Fig. 6 again and see how the grid leaks M and N are supported by the holes in condensers H1 and H2 and wire clips branching out from the switch side of the rheostat connections. Bend these two wire clips into shape and solder them in place as shown. After this you can connect the grid terminal of transformer I with the grid terminal of socket J2, as shown in Figs. 2 and 8. The tuning circuits have been left until the last to allow more room for work on the lower part of the panel. Wire the secondary circuit first. Run a wire from the rotary-plate terminal of condenser D to the plus filament terminal of socket J1 and continue it across to the bottom connection of the secondary coil B. Next, run a wire from the stator- plate terminal of condenser D to the top terminal of coil B. Solder one terminal of grid condenser E to this wire and connect the other terminal of condenser E with the grid terminal of socket J1 with a piece of wire about 14 inch long (see Figs. 2 and 4). This completes the secondary circuit. i Dig plate circuit is finished by con- necting one terminal of coil C with the plate terminal of socket J1, and the other with the P terminal of transformer I. Between this latter wire and the wire from the rotary-plate terminal of con- denser D, solder by-pass condenser F (see Figs. 2, 4, and 8). The antenna circuit wires are shown clearly in Figs. 4 and 7. The top end of the primary coil A is connected directly with binding post No. 1, and the bottom end of the coil is connected with the ter- minal nearest panel S of condenser G. Now, connect the remaining terminal of condenser G with binding post No. 2, with spaghetti covering on the part of the wire under the panel. This completes the wiring of the receiver. HOW TO INSTALL THE RECEIVER The first step is to remove the wooden partitions in the record compartment of the phonograph cabinet. Then set a wooden strip 34 inch thick around the inside of the cabinet about 3 inches inside the door. Fasten this strip with wood screws. A door should be cut in the back of the cabinet, as in Fig. 1, so that the dry-cell B batteries can be placed in it behind the set, and so that tubes can be changed and antenna connections made. The easiest way to cut the door is to mark it off with a pencil, drill a hole at a corner, and saw down one side with a keyhole saw. Now fit the hinges across the slot and screw them firmly into place. Next, saw down the opposite side and fit the latch or bolt. It is then a simple matter to saw across the top and bottom and you will be sure that the hinges and latch will fit perfectly. Below the bottom edge of the door drill holes for the antenna and ground con- nections and the wires to the A batt The receiver now can be placed wit the panel against the wooden strip ; holes drilled near the edges for we screws to hold it in place. dei The storage battery can be keyt in the nearest closet, and if care is ok served jn | the wiring of the antenna and groyng connections and the wires to the A bat- tery, no one will notice that there is aradio receiver in the room when the Phonograph door is shut. TO OPERATE THE RECEIVER |. After the installation is completed, the || necessary connections with the antenna! and ground and A and B batteries “a made, the rheostats K1, K2, K8, and Ka} should be turned off, the tubes inserted in | the sockets and the switches R1, R2, and} R3 pulled out. Then the rheostats} shown in Fig. 3 should be turned on} slowly, one by one, until the tubes glow | dimly. Next, insert the loudspeaker plug’ in jack Q and turn the dial of condenser D slowly until a signal is heard. As soon ag’ you hear a local station, turn all the theo’ stats up slowly until the point of maxp mum volume is reached. Then place the plug in jack P1 or P2 and turn the tickle} | coil dial C until the point of maximum volume with perfect clearness is reached, After a little practice you will find the way to turn the tickler dial so as to get maximum regeneration without oscilla tion or whistling sounds. | Switch F1 cuts off all the tubes, while: switch R2 cuts off the last two tubes, and switch R3 cuts out only the last tube You will note that the arranger ent of th switches is such that they control # tubes that are connected with the jad immediately under them. Thus it is @ to form the habit of pulling out @ switch when plug is inserted in the jack ' i Recent Publications The New Theories of Matter and the} Atom, by Alfred Berthoud, professor of} physical chemistry at the University of} Neuchatel. A comprehensive history of} this fascinating phase of science, pre} sented in understandable language. The : Macmillan Company. H Food Products, by Henry C. Sherman, |@a Ph.D., Se.D., professor of food chemistry, if Columbia University. New edition. The/ay Macmillan Company. ai Elements of Electrical Engineering, by George D. Shepardson, A.M., M.Bg Se.D., professor of electrical engineering, University of Minnesota. The Mat millan Company. : Handbook of Direct Currents, by Ke Graham. One of the “ Railwayre Handbook Series.” Simmons-Boardma Publishing Company. ” Meal Planning and Table Service, WY N. Beth Bailey, associate professdly Household Science Department, lows State College. A guide for housewive who have no maids. Illustrated. 1 Manual Arts Press. © This seal on a radio or tool advertisement signifies the approval cf the INSTITUTE OF STANDARDS. See page 33.