Popular Science Monthly 1921-08: Vol 99 Iss 2

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JUL 12 1928 300 es of Inventions and Discoveries |Pepular| 35! Science 4 ) =f amie Ae es NR RIESE eT Factory-Built House of Concrete Delivered _ for $1500—See page 15 25 CENTS |

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Along with every set goes @ year’s Consult- ng Membership in the A= ~s i ¢ an oy ety (regular price $12). Consult our ex- perts without charge, Partial List of Contents: Automobile Motors Welding Motor Construction and Repair Carburetors and Settings Valves, Cooling Lubrication Fly Wheels Clutch Transmission Final Drive Steering Frames Tires Vulcanizing Ignition Starting and Lighting Systems Shop Kinks Commercial Garage Design and Equipment Electrics Storage Batteries Care and Repair of Motorcycles Commercial Trucks Gas Tractors 2128 Blueprints of Electric Wiring =r Diagrams _— * 6 bi, es f Why Dont You Earn BIG MONEY “ Big jobs are just waiting for men like you to fill them. The ‘v bile game has grown so rapidly that there’s an opening everyw 1¢ a fellow qualified to hold a worthwhile job. No schooling or a, ticeship needed—if you will only realize that now is the time f: to get into this big-pay game. You, like thousands of oth2r will soon be enjoying a real job thru the help of these great mobile engineering books. FREE Examinatic .. The very latest, "up-to-date six volume library—by fifteer greatest auto experts—containing absolutely everything to know about the upkeep, care and repair of motor tractors. Written in plain, forceful English that anyo stand—over 2700 pages, 2000 pictures, diagrams and blu in flexible American Morocco, gold stamped. Your set \ immediately for 7 day” free trial if you send us the ci Send No Money You don’t have to spend a penny in advance to examine these valuable your home or shop. Just fill in the coupon, pay the small express charge w. books arrive—and they are yours for seven whole days to study as you want! Bargain Price for You! Only a Dime a Day! We are letting you share in our good {¢ you decide that these books will're fortune! The price on these big-pay > 2 books i reduced from $45.0010 $2480) then only 00 month until our sp : ; bargain price of $24.80 is paid. De.. That means our manufacturing cost has A I J been lowered. by big production—and stand in your own path to bigger thing Fill in and mail the coupon now! ‘ you get the benefit! AMERICAN TECHNICAL SOCIETY i: Dept. A-20-C, Chicago, U. S. A. 4 cs GS SD GSS GS SS ess ees ee es es es hee ac AMERICAN TECHNICAL SOCIETY nA esw Dept. A-20-C, Chicago, U. S. A. - gH sgn O Please send me set of Automobile Engineering for 7 days’ examination; at Oe 7 charges collect. I will examine the books thoroughly and, if satisfied, will Ser. pad be within 7 days and $3.00 each month until I have paid the special price of $24:8Qs7qlf1) 54 iu not to keep the books, I will return them by express at your expense. 5nrsos¥ o* gdgicr RTS ice Sa ee Te eee . v oH —$: dvs ‘ 4 - eoece SOSHHSSSHSHSSHHSHSHSHSSSHHSHSSHHSHHHSESEE ,@ceccccercoegveses ‘ ta 29 ;? Address........ cedsbbaeeehhaosbaere Q yIce oH NS ecccce eeccece te eecceccccccccccecoccccvessceescccsssscoesestnhe tit) "on 2 1 Ymsanros dt besaos TOs i Yiaidd to

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August, 1921; Volume 99, No. 2 25 Cents a Copy; $3 a Year Published in New York City at 225 West_Thirty-ninth Street Complete House Delivered by Truck for $1500 A project to break the housing deadlock RE you to-day, like millions of other Americans, long- ing for a home of: your own? Are prohibitive building costs keeping you a slave to your land- lord and to an excessive monthly rent? Approx- imately 7,000,000 fam- ilies in this country own their own homes. It is estimated that, out of a total of 23,000,000 fam- ilies in the country, at least another 7,000,000 hope to own a _ house when building conditions permit. There are about a million marriages per- formed annually in the United States. With an already existing shortage of some 1,500,000 homes, where are the dwellings for these new families to come from? Relief at Hand? I believe that partial relief can be brought at once to many of you who are suffering from these conditions, by factory production of complete, low-cost concrete homes, to be delivered to you by motor-truck. Our shoes, watches, toothbrushes, hammers, hats, saws—all are fac- tory-made, all made by machinery. By quan- tity production the cost By Simon Lake “Buy your building-plot now, while land values are low, telephone for a $1500 house, and move into your own home next -day!”’ This is the advice of Simon Lake, distin- guished engineer and inventor of submarines. And he has backed up his advice by the actual production, in a factory at Bridgeport, Con- necticut, of concrete houses to be delivered complete to the purchaser by motor-truck. Ten factories of this kind in various parts of the country, each making motor-truck deliveries in an area of 7500 square miles, could produce 125,000 houses a year. The Popular Science Monthly is planning to publish in an early issue a supplementary article covering other remarkable types of com- plete factory-built houses now in the market. Specially designed motor-truck delivering through the streets of Bridgeport one of the completely equipped con- crete houses built in Simon Lake’s factory. These trucks will deliver houses a distance of fifty miles 15 is decreased to a fraction of the cost of the hand- made product. Imagine what you would have to pay for a. handmade toothbrush?! Perhaps the contrast is the great- est in’ the case of. pins. Before the introduction of machinery a single workman unaided. could make only ‘d ‘few pins a day; the daily product of a workman is now about 15,000,000 ‘pins.a day, complete and stuck in papers. Our Ancient Methods But in building houses the process we use is that of the times of Julius Caesar and of William the Conqueror. Each house is built sepa- rately, just as formerly each pin was manufac- tured separately. Logically our vitally needed nevy homes should come from the same place as shoes and stockings and chinaware and linens and canned goods—from~ factories. Such a factory is in operation to-day near Bridgeport, Connecticut. It is planned to erect others in seven or eight strategic points through- out the country. Of course these plants alone would not be able to

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ee ee PS OO RIEE ARE PADS emcaNgEAS eco CR PRT TRE NED SRST: Na RN a ice Li RPE on > ween sk as pe rere ne Be EE EL IGS aed ER oes aT AER Bete IE iy Sa ELE RE aT RE EE BRO a oe o- —> “ ae Se Here’s a whole row of ready-made houses. Observe that they do not look any more like one another than any row of city houses built at one time solve the housing shortage. But, working at capacity, they might alle- viate much of it. These factories will make perma- nent, damp-proof, vermin-proof, very nearly heat-proof and_ cold-proof houses, constructed of monolithic re- inforced concrete. They are factory- made, with all that this means in economy and speed; yet they can be adapted to your individual taste. These houses, which will be delivered to your door by motor-truck, are so cheap that any man with a moderate weekly income ought to be able to finance the purchase of one. What You Can Get for $1500 For instance, our unit home costs $1500. It contains a combination living- and dining-room 12 by 12 feet; a kitchen 8 by 5 feet; a bedroom 12 by 8 feet; a bath 5 by 4 feet; and a sun- parlor, closets, and dressing-rooms as well. In these homes we are introducing three absolutely new features: First—A radical innovation in the manufacture of homes. Second—An ingenious means of delivering them. Third—A unique design for them. The houses are constructed of the commonest of materials, sand and gravel, cast over gal- vanized steel reinforcements. The materials are brought into the plant on railroad cars and are then lifted by a grab- bucket into two huge hoppers, placed upon an enormous mov- able crane, which is the most important piece of apparatus in the plant. The cement is mixed and then flows into the forms. There are two strong forms made up of heavy steel girders and timbers to resist the pressure due to the weight of the semi-liquid concrete. Within these are placed sheet- iron cores internally braced to resist pressure. These cores render the walls of the new house hollow. The concrete fills all spaces between the cores and the outer forms. Hollow walls mean a house cool in summer and warm in winter. Since the house is poured in one solid concrete unit, it is virtually in- destructible. Before the cores are placed in position they are put through a bath of asphalt, and a coating about one eighth of an inch thick forms on them. This serves a double purpose: first, it makes a coating on the inner lining of the walls and results in this concrete house being water-proof and damp-proof. Second, after the con- crete gets its initial ‘‘set,’’ air heated to 180 degrees is circulated through the cores, and this, melting the asphalt that remains on them, facilitates their withdrawal. Usually this would be a matter of days, but the warm air sent through the cores completes this proc- ess within three hours. The crane then lifts the house and deposits it in another part of the yard, where it stands for two weeks to per- mit the cement to harden. The house, or house-unit, is then ready for deliv- ery; for in the meantime the roof, the plumbing, the electric wiring, and This five-room bungalow was made in a factory. It is a one-unit house, and contains a combina- tion living- and dining-room, a kitchen, a bed- room, bath, sun-parlor, closets, and dressing- rooms. It cost $1500 ‘ 16 Popular Science Monthly all the other interior fittings have been added. But how do we keep these homes from bearing the stamp “factory- made’”’—from being as much alike as peas in a pod? The exterior of the building may be altered in any way to suit the owner. Friezes and frescoes may be added; roofs can be varied in many different ways. Tile or shingle may be superimposed upon the slab of reinforced concrete that is the real roof and that will never leak or decay. While the concrete is still moist, paint or liquid dyes will be sprayed upon it —any shade you desire—and a century from now the color will be as clear and fresh as when the house is delivered to you. To deliver these houses I have de- signed a specially constructed ten- wheel steel truck with a low hung steel drop frame on which a house can be placed and delivered within a fifty- mile radius of the plant. A house can actually be put in place and made ready for occupancy on the very even- ing of the day on which it leaves the plant. The Second Story Is Delivered First ! A cellar is not essential for these houses. The floors are cold-proof and damp-proof. Coal may be kept in a utility building at the side or in a special bin concealed on the roof, from which it may be let down to the stove by turning a lever. The house may be placed either on a cellar, on piers, or on a solid wall. So it is a comparatively simple matter, with the aid of the elevating apparatus carried by each truck, to put the house into its proper position. When the residence is to be of two stories, the second story is delivered first, elevated to the proper height, and then propped in position on special struts until the first-story unit is brought, when the second story is lowered upon it. Robert C. Lafferty, the originator of these houses, started with the idea that in the ordinary house there is too much waste space. The din- ing-room is used only a few hours a day; the bedrooms are not employed at all in the day- time. Accordingly, he had designed a home unit measur- ing only 28 feet & inches by 12 feet 6 inches, in which every cubic foot does duty for the greater part of the twenty- four hours. In the daytime our house unit is a bungalow with a> living-room, glassed-in sun- porch, a_ kitchen equipped with twentieth-century labor- saving devices, a den where a man can be alone with his pipe and a book, and two dressing- rooms with plenty of space for

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vi i IM I As a Oo aS ct cto se id ve be on ly ch er wo ed ht, ory ry tor lea too lin- few are ay- had sur- by ery the \ty- use h a un- ped Dor- ea pipe ing- » for August, 1921 chiffonnier, dressing-ta- with a cost of 40 cents ble, ete. for a cheap frame house When mealtime comes Facts about the Unit House up to 70 cents for one the housewife detaches a 7 of stone and wood. But mirror from the living- HE single-unit house may be placed on these houses will last room wall. This lets six concrete piers. The specially treated forever, with almost no oe forms a — hollow concrete floor obviates the necessity of a — . be- ortable dining-room tz- : at this new house- ble for six. A revolving any further protection from dampness. building method is the service connects the ta- The new concrete house is fireproof and method of today and of ble with the kitchen and sunproof. No repainting is required. the future, and that, just brings dinner to the Some of the furniture is built in and this as the great majority of table; when the meal reduces the furniture bill. the men who read this is finished, it takes the empty dishes back to the kitchen. © The mirror the summer. The house is warm in the winter and cool in article go to a shoe-store Its hollow-wall construction for their shoes and toa men’s-furnishing store snaps back into place ‘makes it like a vacuum bottle. for their shirts, more and and you have a living- A small efficient heating-plant is supplied more families will want room again. with coal from a small coalbin that may be a = —— , 1 ; at come wi omes ‘Where the Beds Go in a 2 om the roof. The coal feeds down by exactly and scientifically the Daytime A turntable is used to serve the dining- When it is time to re- room table direct from the kitchen. tire, a touch on a small rope pulley that hangs a Room beside the window of the den brings down a bed from a paneled space in the ceiling. On the sun- porch is a similar bed. The base cost of one unit such as I have BEd ROOM described is $1500. This includes delivery, the kitchen sink and the necessary plumbing, lin- oleum, etc., beds and other fixtures, but not the bathroom fixtures or the plumbing that goes with them. As _ orna- mental roofs or other extras are added, naturally the prices increase. Two or more units are employed in conjunction where a !arger house is required. Thus two units, divided into six rooms, cost $3000; three units, | | | | iz IF | t Thee Le ae yaa’ ha Bridgeport, Connecticut, boasts the first factory constructed under con- ditions that make it possible to give maxi- mum value for the dollar. dein Saved—$4200 on One House Alone ‘ ® J a ° z unit house with a garden space in the center making an ample home for a family of moderate means, cost $4500, and six units, composing a larger dwelling with many luxuries, $6000. The cost of these houses is about 50 cents a cubic foot, as compared ae Oa tl n hi | nly recently a ma | = NY e . i Se Pee —, hoa came to us with a build- | . ‘ti = | er’s bid of $10,500 for a | ek - frame house; we ar- ma 4 ri; £ 3 ranged a bett | {Perea Living Room = Pasrrage BepRoon " 4: PAAGE : t ange a © er, perma- ee fre aaah eee eter Sate le home for him at a a oe | cost of but $6300. The Pere ee en - method can also be used 1 e left and above are shown two-unit bunga- ° lows that are virtually the same as to the number for the A construction of of rooms, but that are arranged to accommodate two-family homes, apart- the available lot space. At the right is a three- ment-houses and _ fac- tories. More and more I am convinced that I spoke the truth when, while our plans were getting under way,-1 wrote to Mr. Lafferty: “T am beginning to think we really have introduced something new into the art of building construction.” unit plan. Several houses can be seen in proc- where ready-made concrete houses are made. ess of manufacture. It will also be noticed that The factory buildings were also made on the 17 some of the skeleton houses are used as offices

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spevatebe et = co eaceetncael 2S ght Seat ot ld aS at ea a aR > pee a as meee bs ey. SS BS SR AISLE AE WEDS Ete, TERE EN ES. EET AS gee Lh ad eee ae AS > wei, Pt a Ae e: ee eae Se SS baat St Sees Sos ee a SS al SEH Hitt ai ie Hituni nhunn fOr Ww irl! HE idea of driving a boat with an air-propeller is not new by any means, but this particular boat illustrated below has many original features that make it stand out from any of the other boats that have been de- veloped along these lines. The weight of the upper works is supported by two special metal pontoons. The displacement of these is amply sufficient to support not only the weight of the engine, but it will also carry four passengers with perfect safety. An aviation type of engine is used, Giving the Times Building a sponge bath. The walls of the building were painted with an acid solution, after which they were sponged with clean water Spring-Cleaning a Skyscraper IFTEEN years ago the creamy white terra-cotta walls of the lofty Times Building in New York city were new and clean. Gradually they became gray and dull, and in the spring of this year it was decided to have them cleaned at a cost of about six thousand dollars. It took twelve men two months to do the work. Six scaffolds were required, two men work- ing on each scaffold. The old way to clean: the stone walls of a building was to blow grains cf sand upon the surface with compressed air. But the beautiful glazed terra cotta of the Times Building would have been spoiled by a sand-blast. How then could the workmen get rid of the coating of grime? They made use of an acid solution prepared espe- cially by the manufacturers of the terra cotta in the walls. The solution is applied by means of a painter’s brush. A few minutes later it is sponged off with clean rinsing water. So small an amount of liquid is necessary in this process that it was not found necessary to erect an overhead canopy to protect pedestrians on the sidewalk below. New York has more than eighty buildings of twenty or more stories. From an architectural standpoint they are the most beautiful build- ings of their kind in the world, and it is the pride of the city that they should be kept white and clean. ? Popular Science Monthly Sixty Miles an Hour in a “Wind-Boat” and the propeller is connected directly with the crankshaft. This is the really unique feature about the boat as it is the first time it has been done on boats of this kind. The propeller is usually connected with the crankshaft by means of a heavy chain. The motor is rated at one hundred and fifty horsepower. A water-screen or apron is placed at the stern of the craft to prevent the propeller from getting wet when the water splashes while the craft is running at high speed. ; Mr. Allen H. Loughead, of Santa Barbara, California, who owns this ‘“‘wind-boat,” claims that it can attain a speed of sixty miles an hour. © International Film Service Though the idea of an air-propeller on a boat is not new, this wind-boat has many original features Stenches to Warn Miners of Danger OST signaling devices appeal to the eye or to the ear, and the principal means of sending a warning from the surface down to the miners in a metal-mine has heretofore been by at once.” e These miners have just ey detected in the air an odor that means, “Come to the surface The odor is produced by introduc- ing a_ vile-smelling liquid into the com- pressed-air line messengers, electric gongs or lamps, telephones, interrupting the flow of compressed air, or introducing water in the compressed-air lines. Recent investigations of the Bureau of Mines in cooperation with several large metal-mining companies have demonstrated that warnings which are perceived by the miners through the sense of smell are easy to install and are on the whole as effective as any other system that has heretofore been used. Briefly, the odor system of warning consists of injecting from one half to one pint of a very strong-smelling liquid (preferably one with a vile odor) into the main compressed-air line at the surface. The air current quickly vapor- izes the stench liquid and carries it to all parts of the mine where com- pressed air is used. Thus miners in working places operating air drills re- ceive a positive warning to come to the surface within a few minutes after the stench has been introduced at the mine- or pit-mouth. ~~ A ot eet ee Oe COFCO oe LU gL CU a a a a ee ee ae ee ee aL ee ee ma —-_ 6 be Oe

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August, 1921 Harness the OES a stream flow through the corner of your farm? If so, get busy at once and put it in harness, for it represents horsepower going to waste. Its energy, created by the same force of gravity that moves the current, will provide electric lights, or it will furnish the elec- tricity for storage batteries; or it will pump water into irrigation ditches. The cheapest machine yet de- vised for raising water from a river to any desired level is an invention of F. L. Gilman, of Los Angeles. It is practically a power plant operated by the Streams and Make Them Do the Work quired to control it, not even a caretaker to see that it does its work. However, a _ channel _ with some protecting wall must be made to obviate the catching of drift. This could be easily cone, and there is absolutely no ex- pense connected with the operat- ing of the simple motor. Until the river runs dry or its paddles wear out, the harrow-shaped ma- chine will continue to pump day and night for the thrifty rancher and his thirsty acres, thereby saving much labor. current of the stream from which the water is taken. The model recently demonstrated before the local Chamber of Commerce forces eighty gallons a minute through a three-inch pipe to a height of eighteen feet, working without a hitch. Engineers declare that this supply is sufficient to irrigate one hun- dred and sixty acres. It is a simple contrivance to be anchored in midstream. Like the old- fashioned ferry, it depends on the cur- rent for locomotion. The rudder re- verses itself automatically as it reaches the side of the river, giving a swaying motion continuously and of indefinite Here is a power plant that is operated by the current of the stream; it will furnish electric- ity or pump water in irrigation ditches duration. Pistons connected with ten-inch pumps are attached to the swaying beams, which allow for a twenty-two-inch stroke. Six horse- power is thus obtained; this may be greatly increased by increasing the size of the machine or by placing- others in the current. The initial cost is less than that of an ordinary pumping plant, and once installed no further attention is needed; no expensive engineer is re- te Ic & Pistons connected with pumps are attached to beams swayed by the current, and six horse- power is obtained Filtermg Noises Out of Radio It is done by the use of static eliminators NE of the greatest troubles in radio communication is caused by static interference. Static elec- tricity in the air flows into the aerial and passes through the receiving apparatus, producing ugly noises that make long-distance communication almost impossible. the ears of the operator by means of binaurals attached to the end wall of the smaller cylinder. The filtering action is simple. It is well known that any pure sound has a definite period of vibration and there- fore a definite wave length. By sliding Static eliminators, which are reported to be doing marvelous work, have been developed at some of the transatlantic sta- tions, but they require vast areas and expenditures for their erection. For this reason—ordi- nary land or ship stations can not use them. The device here illustrated offers a means of eliminating static and other interferences at the same time. It is an acoustic tone-filter. It will be seen that there is a telephone receiver attached to the larger of two brass tubes constructed so that one fits concentrically within the other. The signals pass through this receiver and into the tone-chamber formed by the two cylinders. The filtered sounds are carried to The use of this resonant sound chamber elimi- nates the disturbing noises produced by static interference in the reception of wireless telegraph and telephone messages 19 the smaller cylinder in or out of the larger one until the space encompassed by the two is in resonance with the sound coming from the telephone re- ceiver, any acoustic wave length may be found. Obviously the chamber will not be in tune with more than one » signal at a time, any more than two similar organ pipes would produce different notes. This does not hold true when the sig- nals from two or more stations are of the same resultant tone, though such a_ condition is almost unknown. The sound produced by static is of a comparatively low value, whereas the modern radio trans- mitter produces a musical note at the receiving station. This difference in tonal quality is taken advantage of in eliminat- ing the static. With loud signals, it has been observed that the resonant action of the acoustic chamber upon the diaphragm of the receiver results in an amplified signal intensity. With weak sig- nals a decrease of intensity up to 30 per cent has been observed.

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pee mnie oan a a Popular Science Monthly How the German Cables Were Diverted A war measure establishes a scientific fact By P. J. Risdon English correspondent of the Popular Science Monthly HORTLY after the declaration of ns war, all German telegraph cables were cut. Mr. C. H. Gray conceived the idea of utilizing these cables, and, on behalf of the French government, undertook the operation of converting them. The success of the operations was of immense importance, proving that the recovery in good condition and relaying of deep-sea cables is prac- ticable. One of the German cables was 3905 miles long, in two sections, one from Emden to Teneriffe and from Ten- eriffe to Monrovia, West Africa. The Task Was Begun in 1915 The cable steamship Dacia left London in August, 1915. The cable was picked up at a depth of two and one quarter miles by means of a special grapnel, and hauled to the surface. On September 11 it was cut in shallow water off Brest, the southern end was buoyed, and 150 miles were recovered to the northward. One end of this recovered portion was landed at Brest, and nearly all was relaid, and the other end spliced to the buoyed end off Brest. The German cable was under cables belonging to the Allies, .which necessitated cutting and grap- pling it again. A heavy cable was then laid out from Casablanca and buoyed. Drawings made by G. H. Davis From Brest to Monrovia the Dacia steamed, recovering severed German cables. Hardly was the task accom- plished than the ship was torpedoed and sunk by a German submarine From Teneriffe the German cable was again grappled in deep water and lifted, and a length of 334 miles was re- covered, of which 328 miles was relaid and spliced: to ‘the buoyed. end off Casablanca. This completed the con- version of the first section, and thus within four months of beginning work 1400 miles of cable between Brest and Casablanca were at the French govern- ment’s disposal, less than 500 miles of the cable having been picked up and relaid. How the Cable Was Located The second section from Teneriffe to Monrovia was a task of greater magnitude, because a greater length had to be picked up and relaid in a depth averaging two and one half miles, much farther from its original position. A second length was laid out from Casablanca. South of Teneriffe the cable was cut and recovered shoreward. This was landed and laid out from Dakar, and buoyed. South of Dakar the German cable was cut again in deep water, and 115 miles to northward was recovered and relaid to the buoyed end off Dakar. The cable was then cut off Monrovia, and picking up was continued in deep water until 673 miles of good cable had been recovered, of which 601 miles was spliced into the cable off SECURING ENDS OF A BROKEN CABLE broken cable arene enna Cahle ne ‘® ee Seaman proceeding 0 whle mar i\ affendiun le pec es all buoy i fo Red er Jaw closed & knife cutting cable. i ee : Cable cut away & left LUCAS CUTTING GRAPNEL FOR CUTTING CABLES | a REAT DEP a3 ad ¥ end securely held in jaw of grapnel © Modern Publishing Company The cable-ship Dacia picked up the German cable at a depth of two and a quarter miles, and hauled it to ‘the surface: the feat necessitated the overcoming of many serious difficulties A special grapnel was devised for the purpose of raising the cable; the operation was a very delicate one owing to the fact that the German cable was laid under those of the Allies 20

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August, 1921 oe feete mae | sone 4 ee i { © Modern Publishing Company This is the cable-ship Dacia, which was outfitted during the war for the work of retriev- ing German deep-sea cables and of rearranging them for use by the French government Teneriffe and relaid to the buoyed end off Casablanca, a distance of from 1400 to 2000 miles away from its previous position. The cable was found by grappling for it at right angles to its length, using about one third more rope than the depth of the water. A good portion lay at a depth of two and one half miles, and to have attempted to lift it on the bight would almost cer- tainly have resulted in straining it to breaking-point. To overcome this dif- ficulty, a special form of grapnel was used, by means of which, when the cable had been found, it was cut on one side and the other end was secured and raised to the surface. Owing to the fact that the original cable in this vicinity had been cut at the outbreak of war, it had to be grap- pled for again in deep water when the ship had picked it up to the point of severance. The magnitude of the task under ‘war conditions can scarcely be over- rated. Imagine fishing in the night for a cable lying two and one half miles deep in the sea, cutting it at that depth, hauling the end up, and splicing and relaying in new positions, knowing that submarines were always near and the ship liable to attack. In little more than two years the Dacia’s work was completed, and almost immediately afterward her armed escort was torpedoed and the Dacia sunk by a submarine. Mr. Gray’s persistence and success were appreciated by the French govern- ment, who conferred upon him theCross of Chevalier of the Legion of Honor. METHODS OF SPLICING BROKEN SUBMARINE CABLES ORDINARY METHOD OF SPLICING SHEATHING WIRES Crinoline Cabie being uncoiled. a passing upio the deck a finally into the sec. Core repaired SECTIONAL VIEW OF FINISHED SPLICE soldered & served OVERLAPPING METHOD OF SPLICING with tape, over this serving of brass ~~~ a Dividing a fape.% followed \ [o cleat ~ Coiled by jute v cable vg f » -: acta Juke Vute Wires Wires Wires \ Wire Japping \wire 4apping Wire Japping Finished served with farred © Modern Publishing Company Four months after the work of reclaiming the German cable was started, the ends were respliced by the method shown here and then it was used by the Allies Showing the interior of a cable tank of the ship Dacia, where the cable was wound on a huge spool until it was relaid Pd en a Re a 2s naatel a

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ERS EE OTE AIOE TAILS 7 TEST SEY APPR a _ ee I mnie, sein eter we add c 0, RE TRI Fate RS: Se NOM toa ate ane Stel . Prec L TS 12 RATS a ee a sh Se SE eS EE ene aerate aa oO Re ESE SE: ie St a Se ees a Gong a sb —— peeaee ty ere fore ERS a BP teeta eer on Sues PAK cee With this instrurnent the pupil can observe his own vocal cords, while the teacher is able to check his observations You Can Watch Yourself Talk XN accurate knowledge of the larynx, the main organ of the human voice, is of the highest importance not only to the medical practitioner, but to the singing- master, the teacher of deaf-mutes, and the student of language who is trained in modern phonetic methods. Anatomy teaches the constitution of the organ, the arrangement and interconnection of its various parts. How it works in producing the infinite variety of human speech is studied by phonetics. Popular Science Monthly Protect Young Chicks from Rats HE telescoping metal chicken-coop and wire feeding- pen shown below were devised to keep out rats and other enemies. While the coop and feeder are separate units, they may be connected to provide a runway six feet long. The coop is made of galvanized iron and looks like a small traveling-bag. A wire section is made to telescope inside the coop proper. When this wire section is ex- tended, it forms a runway for the brood hen and the chicks. Its outer end has a small door at the bottom and a ventilator at the top, so that when pushed in entirely the coop has sufficient air. The feeding-pan is for the small chicks and consists of a bottomless wire box with metal ends and doors. f. SUDING WIRE » EXTENSION of The runway at the left of this telescoping chicken-coop admits chicks, but is not large enough for the hen The Sun Does the Family Cooking Garcia’s laryngoscope was the first instrument that made it possible to study the human voice in a scientific way by means of a beam of light pro- jected from an outside mirror. A de- cided advance was made by Harold Hays’ pharyngoscope, an apparatus comprising a narrow tube with a minute inside lamp, with which nearly all vocal processes can be studied. The autophonoscope, designed by Professor Panconcelli-Calzia, director of the Hamburg Phonetic Laboratory, is a new scientific instrument for the study of the human voice. It comprises a tube the end of which is introduced into the mouth. The opposite end is intended for the ex- perimenter, while the person experimented on (or the pupil receiving a lesson in phonetics) sees his own vocal organ in the branch-tube. The center tube contains a half-transparent mirror. The instrument also comprises a lamp and sometimes a lens system. The following are some of the phonetic processes dem- onstrated by means of this apparatus: normal breath- ing, noiseless and noisy in- spiration, violent expiration, coughing, clearing one’s throat, swallowing, and the action of the vocal cords with all varieties of articulation. VERY boy knows that with the aid of a magnifying-glass a paper can be ignited and wood burned by focusing the rays of the sun upon it. That being so, why can’t the sun’s heat take the place of coal? Dozens of inventors have asked themselves that question, among them the famous Captain Ericsson, inventor of the Monitor. He spent about $150,000, and then discoveerd that, although the sun’s heat costs nothing, a sun-heated boiler is so expensive that it is cheaper in the end to use old- fashioned heating apparatus. Dr. C. G. Abbot, of the Smithsonian Insti- tution, has attacked this problem, but in a purely experimental way. He knows that the day when the sun will take the place of coal is still far off. In his apparatus we find the usual parabolic mirror that focuses the sun’s rays on a boiler—in this case a blackened tube filled with oil. Dr. Abbot uses oil because it boils at over 400° F. Water boils at 212°. Hence the oil absorbs more heat. The oil flows into the tube from an overhead reservoir and then back into the reser- voir in a continuous stream. The oil transfers its heat to two cooking-ovens. A few hours of sunshine are suffi- cient to heat the oil to such a temperature that cooking can be done all day. It does not sunny and the afternoon cloudy. The ovens will still he hot enough for any pur- pose except frying. Since the sun moves slowly across the sky, the mirror must follow it, so that the rays will always be concen- trated on the tube. This is accomplished by means of clockwork. By means of a parabolic mirror, oil, tubes, and a reservoir, Dr. C. G. Abbot has been able to utilize the sun’s rays for heating two ovens built in the side of the reservoir 22 Dr. Abbot did all his cook- ing last summer with this solar kitchen stove. matter if the morning is

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August, 1921 How X-Rays Make Life Safe for the Bomb Squad Why was this a “sus- picious” package? We don’t know. Perhaps the recipient had an enemy, or had been getting threatening letters. Anyway, he decided to find out what was inside with- out taking any risk For some reason, the customs inspector sus- pected this young woman’s shoes’ of smuggling. He decided to take their picture— the only other way to settle the question would have been to destroy the shoes Lucky for the man who got that in- nocent-looking parcel in the mail that he had it X-rayed. It contained a deadly bomb that would have exploded on opening And this is what the customs inspec- tor’s X-ray picture showed: nails in the wooden heels, a metal buckle, and—two rings set with jewels worth thousands of dollars Raising Wrecked Ships on Cushions of Air NEARLY two years ago the gov- ernment dredge Florida was caught in a storm off Anastasia island neare St. Augustine, Florida, and wrecked, the master and several of the crew losing their lives. Shortly afterward the U. S. S. Isis, in the service of the Geodetic Survey, was sent to the scene to chart the wreck as a protection to coastwise navigators. She too was caught in a storm, which swept her on to the submerged tower of the dredge. Her hull was punctured. The crew attempted to run her ashore, but before they could do this she foundered. Since then three at- tempts have been made to salvage the Isis, and each has met with dis- aster. The Isis lies in toons. about thirty-five feet of water, so close inshore that she is in the line of the breakers. This and a sweeping, oily land-swell keeps the surface in con- stant agitation. Below a strong un- dertow surges, making it difficult for divers to work. Storms are frequent, and near by on Crescent beach lie the One of the huge inflated balls—resilient, collapsible pon- Although it is filled with air, it weighs one thousand pounds, and is capable of lifting twenty-five thousand pounds in the water 23 bones of a fine four-masted schooner— all that remains of the work-boat em- ployed in the last salvaging effort. A salvaging expedition arrived in St. Augustine recently on the steam- ship Blue Point, employing new prin- ciples. These include a ‘mechanical mole,” which, guided by an electrical control-board on the work- boat above, burrows under the wreck, performing many functions’ hitherto possible only to the human diver; and the resilient collapsible pontoon, which resembles a great football when inflated and exer- cises a lifting power of twenty-five tons in water. These pontoons are sunk about the hull and at- tached tothe keel, pumped up, and bring the wreck to the surface on a cushion of air. -

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a ee Popular Science Monthly Here is the interior of the plain-looking suitcase on the right: manipulating the puppets on wires, Miss Boothe teaches children lessons in hygiene MINIATURE the- ater, which is car- ried from place to place in a suitcase, together with its properties and hand-painted paper stage folk, is being used by Miss Stella Boothe, a specialist in child hygiene, to convey to children the idea that good habits lead to health and happiness. Miss Boothe, whose ability as a lecturer on hygiene for children has been recognized by the United States Public Health Service, perfected her teaching scheme after consultation with some of the lead- ing psychologists and physicians. Her aim is to put “punch” into the health lesson by building around each idea, such as the need for fresh air and the need for sleep, an interesting fairy story acted by the paper dolls while she recites the dialogue. Mary Gay has the principal réle in each of the stories. She goes through many adventures, eventually learning that such things as good food, morning The Problem ERFECTLY honest forty per cent cream leaves an up-state creamery in a can addressed to a New York hotel. When it arrives, the butter-fat content may have shrunk to twenty per cent or less. Somewhere along the line the can has been opened, the cream stolen for sale, and the shortage made up with milk. Many persons handle a can of cream in transit—creamery drivers, railroad employees at sta- tions and in cars, teamsters deliver- ing to hotels and restaurants. De- tection of theft is therefore difficult. Cream-stealing has been one of the hotel man’s grievances—not only the loss of cream but possible con- tamination of a delicate food article in transit. A new way of shipping cream has lately been devised to prevent theft and contamination. Shipments are She Carries a Complete Theater in an Ordinary-Sized Suitcase baths, early rising, plenty of sleep, and much fresh air will make her big and strong. Her early-to-bed lesson, which is typical of the set of stories, lets Miss Boothe’s’ juvenile audiences see her being warned against listening to the Dragon of Ignorance by a night- gowned child who knows that little girls should not stay up late. Late Hours, clad in a cape trimmed with ‘“‘the sparkles from children’s eyes,”’ is chased out of Mary Gay’s room. Throughout the dialogue Miss Boothe manipulates the characters by means of fine wires. Thus far Miss Boothe’s lecture tours in rural districts, and also in the big cities, such as New York, Philadelphia, Spokane, and Cleveland, have met WAC! UUM CAN To prevent cream-stealing and con- tamination of the contents of milk- cans in transit, a receptacle has been put on the market that is locked and can be opened only by the recipient who holds the key 24 After the little figures have told their health stories, they are carefully placed in packets and laid away in the suitcase till the next lesson with remarkable success. The fame of the Mary Gay plays and the minia- ture theater has reached even far-away China. Miss Boothe’s first theater was not of suit- case size by a good many pounds. But one day the idea of using a suitcase came to her, and immedi- ately she set about the construction of a miniature theater. The suitcase she uses in her lectures now is twenty-nine inches in length, eighteen and one half inches wide, and four inches deep. It weighs, when filled with the shellacked paper properties and the characters, each in its envelope, only ten and one half pounds. When on a lecture tour, Miss Boothe needs only to address it to herself at her next stopping-place and consign it to the care of the post-office. The interest of children as old as twelve years can be held easily by the lectures. And oncea university faculty sat for an hour while the dolls danced and Miss Boothe lectured. of Fooling the ga Thief made in a new type of cream-can with double walls and a vacuum, on the vacuum-bottle principle. It is a very sturdy receptacle com- pared with the common milk-can— made of sheet steel and almost like a shell in its thickness of metal. Cream cooled and sealed in this can will retain its temperature with a change of hardly more than two degrees on the hottest day. More- over, the can may be left outdoors in the severest weather, freezing being almost impossible in ordinary shipping conditions. The top of each can, when sealed down, is fastened with a padlock. This lock can be opened by only one key, which is in the possession of the hotel or restaurant man to whom that particular can of cream is shipped. Thus it is thief-proof. dirt-proof, and climate-proof.

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August, 1921 Cities Marked in Light to Guide Airmen Js F the plans of the recent | International Air Con- vention are ratified by the government, the near future will see every city of any size in the United States blazing at night with a number that will enable airmen to tell exactly where they are. The scheme provides for a unit sheet covering one degree of latitude and one degree of longitude, designated by a locality name and by unit digits. In addition to the custom- ary latitude and longitude notations, the local aero- nautical maps are to bear numbers, enclosed in rec- tangles, corresponding to a new system of coordinate reckoning. This new “grid’’ reckoning, with regard to latitude, begins at the South Pole as zero and increases northward by degrees and minutes to 180 degrees at the North Pole; with regard to longitude it begins with the ante- meridian of Greenwich as zero, and runs easterly by degrees and minutes to 360 degrees or back to the Green- wich line. In these designating coordinates, the figures referring to the South Polar ‘ distance are written first. A sheet whose southern boundary is 49° N. (7. e., 189° South Polar distance) and western boundary 2° E. (i. e., 182° from Greenwich) is numbered 139- 182. A dot in the marker will indicate the approximate position of the town to point out landing-places for aviators. will tell an aviator what latitude and longitude he is in

2 3" al <5’ 4°

4 : | “ae : 34 FIG.1

FIG.2 This gives the actual dimen- sions of the figures and special marks. The star represents ' the north and the dot repre- sents the south reckoning (7° W.). The cen- ter illustration shows the marker recently laid near Washington, D. C. Wash-

In the future marks ike the one shown here will be used with respect to the north or south half of the unit sheet. The figure ‘‘9’”’-on the west side of the marker indicates that the town is in the section bounded on the south by 139° latitude (new reckoning); the figure on the east side of the marker indicates the position of the town in the section bounded on the west by 182° longitude (new reckoning). The dot in Figure 1 indicates the town as in the southeast corner of the unit sheet, while that in Figure 2 puts the town as just above the center and near the westerly edge of the sheet covering the unit 54° South Polar distance (36° S.) and 173° longitude, new Such a mark ington is in the upper right- hand corner of the unit sheet bounded on the south and west by 38° latitude and 78° longitude (128° and 282° new reckon- ing), so that the open side of the marker is to the south and the rela- - tive position of Washington on the unit sheet is shown by the dot. ; The Air Service urges that the marker be placed on the right-hand side of every railroad track where it enters the town, so that a pilot lost or bewildered, flies until he picks up a railroad track, which he follows until he sights one of the identification marks on the right-hand side of the track on the outskirts of the city. If only one marker is possible, preference should be given to the north of the town. Fishing for Birds on the Island of St. Kilda Inhabitants of the island of St. Kilda spend muth tite in snar- ing the sea-birds that constitute their chief food. The fowlers are armed with a deal pole, nine or ten feet in length, with a noose made of horsehair and quills.. The fowler pushes his rod along the ground close to a puffin’s head. By a dexterous turn of the wrist he drops the noose over the bird’s neck

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rn —nnemeeprerenet > alate iene ROBTRESE BOT onan sr J BPS: z a kta Sten: mee ae ae vs i pate sti = i aang aie ee Sk sae Popular Science Monthly DETECTING CRY L STRUCTURE © Modern Publishing Company A tiny beam of X-rays is passed through a crystal of salt and then strikes an “ionization chamber” connected with a strip of goldleaf in an electroscope, which moves over a graduated scale and measures the amount of electrical energy that is left in the X-ray after passing through the crystal at different angles. The reflection caused by the different layers of atoms absorbs different amounts of The Braggs’ Apparatus for Studying Crystals energy from the X-ray, and by turning the crystal the electroscope shows how these atoms are arranged. The lower part of the drawing shows the arrangement of atoms in salt as discovered by the apparatus designed by Sir William Bragg and his son. The square shape is the crystal; the dots show the positions of the atoms com- posing it Drawing by S. W. Clatworthy

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yorthy August, 1921 How an Ounce of Iron Might Blow Up a City If man could release the powerful force that holds atoms together the world’s power problems would be solved CIENTISTS today are S probing the secrets of an explosive power capable of blowing the universe to pieces. When Sir Oliver Lodge startled the world with his declaration that an ounce of ordinary matter contained sufficient energy to lift a whole fleet of battleships from the water, he was not talking pure theory. In the past ten years the truth of this theory has been demonstrated. All mod- ern scientists now accept it as a working hypothesis to ex- plain the constitution of mat- ter and chemical action. Do you believe that engines may some day be run with the power hidden in paving-stones ? Did you know that the modern theory of matter—the electron theory—tends to prove that everything in the world, your body included, is made up of electricity? The world appears to be a mass of pure electricity. The full significance of these experi- ments has never been pointed out in an American magazine. The article on this page will open your eyes to revolution- ary discoveries in modern science.—The Editor. crystals might be similarly re- vealed. He extended this in- vestigation and found that he was actually able to count the number of electrons in each atom! The exact positions of the atoms in a crystal were deter- mined by the Braggs and by Dr. Hull of Schenectady by further experimentation. The Braggs invented and used the improved apparatus illustrated on the opposite page. For the first time in history, scientists were able to state definitely that all things in the universe were built up of two things, Almost unrecognized by the general public, two English scientists, Sir William L. Bragg and his son, W. Lawrence Bragg, have actually been studying the structure of crystals with invisible X-rays. They have found how the tiny atom is systematic- ally arranged to build up crystalline matter. Every one is familiar with the old definition of the atom. An atom of iron is the smallest unit of iron that can exist and maintain its identity. Ac- cording to this old view, it is so small that you cannot divide it into two pieces. It has been calculated that if a drop of water were magnified to the size of the earth, the atoms of which it is composed would be about the size of baseballs. Yet after X-rays were discovered, physicists began to wonder whether, after all, the atom was the smallest conceivable unit of matter. For in an X-ray tube there is a glow of bluish light called ‘‘cathode rays” that produce X-rays after they strike a “target.” One day Sir William Crookes held a magnet outside the tube —and the cathode rays were attracted just as if they had been iron filings. “This can’t be ordinary light,” ar- gued Crookes. ‘‘You cannot deflect sun- light or artificial light by a magnet.” Radium Sets Scientists Guessing Then radium was discovered, and it was found that something was being given off by radium—in fact, that part of radium emanation changed into helium. Since radium was an element, this transmutation could not be ac- counted for under the old atomic theory. So a new theory of matter was evolved —namely, that every atom was not indivisible but composite, built up of electrons, moving about a central nucleus, just as the solar system is composed of the sun and its planets. The cathode rays are composed of electrons. Electrons are incredibly small. Tiny as is the atom of hydrogen, its mass is eighteen hundred times greater than that of an electron. > Since everything is made up of electrons and their nuclei of positive electricity, there is actually only one kind of matter. Iron, oxygen, mercury, and sulphur differ from one another utterly, but they differ only because the electrons of which they are com- posed are grouped in different ways inside the atom. Such was the theory and it was greatly strengthened later by experi- mental evidence -brought about by X-ray study of crystals. The old dream of the alchemists, the dream of turning lead into gold, now comes within the realm of scientific possibili- ties. In fact, one element has actually been changed into another by Ruther- ford. A few years before the war it occurred tothe German mathematician, Laue, of Munich, that perhaps X-rays would reveal the structure of atoms. There must be some systematic ar- rangement, since nearly all solid matter is composed of crystals having a regu- lar geometric shape. The number of faces and the angles between them, for example, is always the same for each substance. Surely this invariable shape must be produced by an orderly ar- rangement of the atoms within it. These calculations were verified ex- perimentally by other experimenters and particularly by Henry Moseley; a brilliant young English scientist. SBy turning X-rays on matter he proved that its structure might be ascertained. X-rays will pass through flesh; they make your bones cast a_ shadow. Moseley showed that the arrangement of atoms that form the skeleton of 27 and only two things: positive and negative electricity—positive nu- clei and negative electrons. A Danish physicist, Bohr, proceeded on the hypothesis that the simplest atom, which is that of hydrogen, is composed of a central nucleus of posi- tive electricity around which moved one electron of negative electricity. All the atoms of the different elements have this nucleus of positive electricity and differ from one another only by the number of units of charges that make up the positive center and the number and arrangement of the electrons re- volving about it. Thusin uranium the positive ‘‘sphere”’ is the center of 92. Will the Atom Explode? Curiously enough, all this dovetails into what is called the table of atomic weights. The lightest atom of all, hydrogen, is put at the head of a new table of atomic numbers. Its number is 1. It has oneelectron. Farther down is oxygen. Its weight is 16. It has eight electrons. There is always a simple numerical relation.(number of electrons in atom X two=atomic weight) be- tween the weight of an element and its electrons. Of. heavier atoms, this is only approximately true. What holds the electrons together? Some immensely powerful attractive force. Those who attempt to utilize it are taking their lives—and ours—into their hands. If the equilibrium of an atom were destroyed by changing the positive nucleus, that atom would explode. So might the next, and the next, and the next. In a flash the whole earth might be torn asunder. But if this fearful explosive power can some day be used in orderly fash- ion, transportation, production, and all industry may be given incredible speed, and the world as we know it may be completely made over.

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Hy ¥ SESE lege Popular Science Monthly What Makes Water “Taste”? Microscopic creatures that pollute water supplies By Leon Augustus Hausman, Ph.D. URING the months of spring and early summer there frequently develop, in reservoirs, a host of minute creatures that impart to drinking waters various ‘‘fishy’’ and other disagreeable odors and _ tastes. It is commonly supposed that such odors and tastes are due to the decomposition of fish or other animal or plant forms in the central reservoirs. As a rule, such is not the case. The un- palatable flavors imparted to drinking waters are usually caused by the presence of two groups of organisms, which develop quite naturally within the waters, known as protozoa and- alge. The former are minute, one- celled animal forms, the latter microscopic plants. What Protozoa Are Like The aromatic odors of drinking water, together with the grassy or “hayey”’ odors, are due to the alge forms. These are usually not sufficiently unpleasant to ceuse much discomfort. But the more objectionable odors and strong tastes of fish or of some decaying substance is due to the protozoa. These minute forms are composed of but a single cell, made up of pure protoplasm, and vary in size from two to eight hundred microns. For pur- poses of comparison, it is convenient to note that the diameter of the aver- age human hair is fifty microns. Practically all of the water-polluting protozoa lie below the limits of fifty microns along the longest axis of the body. The noxious odors and Some of the Little Creatures that Pollute Our Reservoirs land 2, Synura uvella: length, 30 microns; brown or yellowish; imparts to water muddy appear- ance, odor like cucumbers, and bitter taste. 3, Cryptomonas ovata: 50 microns; imparts grayish- 700 microns; faintly visible to the naked eye; imparts ‘“‘salt-marsh”’ o guinea: 50 microns; resembles its relative, he- malodes. taste. 9, Euglena san- 10, Glenodinium pulvisculus: 18 mi- green color; in small numbers imparts violet-like fragrance; in large numbers, putrid odor and taste. 4and 5, Uroglena americana: 20 microns; imparts fishy odor and taste. 6, Euglena hema- todes: 40 microns; has reddish granules that im- part ‘‘bloody” hue; taste, faintly fishy. 7, Dino- bryon sertularia: 30 microns; gives off fishy or seaweedy odor. 8, Bursaria truncatella: 450 to crons; one of the least noxious forms; odor and taste, faintly fishy. 11, Peridinium cinctum::15 microns; befouls water with nauseating odor and taste as of dead clams. 12, Mallomonas (species not yet determined): 25 microns; in small num- bers imparts fragrance like that of violets; in large numbers gives off fishy odor; often tints often becomes disagreeable when pres- ent in larger amounts. In many cases the odors and tastes due to protozoa are distinctly characteristic of the species producing them, and so may be used as a criterion for determining the species present in odorous water samples. The amount of the oil (termed by the author “protozoan oil’’) required to produce an appreciable odor in water yellowish drinking water is in some instances extremely small. Thus the oil pro- duced by Synura (Figures 1 and 2) can readily be detected when diluted in water to the extent of one part in tastes are imparted during either the growth or the disintegration of the pro- tozoa. With the growth of some forms certain organic oils are liberated from the body, giving to the water an odor or taste distinctly dif- ferent from that imparted by the dead and disintegrat- ing body of the same species. Furthermore, the odors and tastes from any one form differ in quality as their in- tensity changes. Thus an odor or flavor that is in- nocuous or even pleasant in its aromatic or spicy quality when but faintly detectable, Part of the author’s laboratory, where he carries on the minute and painstaking investigations that have resulted in the discovery of many pests that pollute drinking water 28 Here are nine of the species of water-polluters printed at the top of the page, assembled to show = their relative sizes. They vary from Cryptomonas ovata, fifty microns in length, to Peridinium cinctum, fifteen microns in length

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es o- ed in August, 1921 twenty-five million! That this oil is possessed of remarkable intensity of odor will be appreciated when it is stated that from tests made by the author it was recently determined that oil of tansy, which is intensely pene- trating, does not give of a recog- nizable odor when diluted with more than one million times its volume of water. Since the decaying bodies of the protozoa also flavor water, it is not desirable to resort to methods of killing those forms that have already invaded a reservoir, since this may assist in the liberation of a large quantity of oil from the decomposing bodies at one time. Where this has been done, filtration and aeration of the water by special methods must be resorted to. How Protozoa Are Killed Instead, preventives of the growth of the noxious forms are more to be desired. The simplest of these is copper sulphate. Bags of cop- per sulphate crystals, dragged be- hind a boat back and forth over the surface of a reservoir or lake, quickly kill what few forms of noxious protozoa there may be present, before they have a chance to multiply and pollute the water beyond all hope. Experiments seem to indicate that the introduction into reservoirs of certain of the larger carnivorous forms of protozoa, not in them- selves harmful, may serve to keep in check the undesirable species. The introduction of fish is entirely use- less, since not even the newly hatched fish of any species feed The First Periscope Stowaway N the Princess Matoika, com- ing from Antwerp to New York, one of the officers noticed a pipe sticking out of a pile of coal. He ordered an investigation, and the coal was cleared away. As the coal-pile decreased, the pipe was found to lead to a box. To the amazement of everybody, a stowaway was discovered hiding inside. Although food had given out, he was able to breathe comfortably through his pipe and even to hear something of what was going on above his head. Belgian officers of the law who had searched the vessel for an escaped prisoner routed out twenty-five other men and boys who had hidden themselves in various parts of the boat, but failed entirely to notice the. re- treat of this enterprising stow- away, who said he had embarked _ at Antwerp. upon such minute forms as the water- polluting protozoa such as are here shown. Not only do the water-polluting protozoa impart odors and tastes to water, but they also produce muddy or cloudy hues, rendering it unattrac- tive to the eye as well as to the nostrils and palate. This is true of all of the MICROSCOPE ARC LAMP The ultra-microscope used in experi- ments. The bedm from an arc light is projected through the microscope to the object under observation Nets made of silk of the finest mesh, trailing from small boats, gather the specimens; these nets will take any form of more than twenty microns This enterprising stowaway thoughtfully provided himself with a pipe through which to breathe 29 species when they are present in sufficient numbers, as they frequently are. The most common of our water- polluters are grouped in a drawing reproduced on page 28. The curious creatures are shown as they appear under the compound microscope. In the lower picture on the same page the relative sizes of some of them are graphically indicated. It is inter- esting to note that the matter of size seems to have nothing to do with the relative unpleasantness of these midgets. In order to secure specimens for study in the laboratory, where various experiments with controls, killing reagents, etc., are carried on, various devices have been made for taking them from the water. One of these is shown in a picture below, trailing from a boat. These nets are made of silk of the finest mesh and are capable of taking speci- mens of any size more than twenty microns in diameter. Details of Necessary Study In order to combat successfully the inroads of the protozoa, studies must first be made of the crea- tures themselves, and knowledge obtained of the structure of the forms, the nature of the protozoan oils that they excrete, their life histories, length of life, and the best reagents for their destruction. The subject makes an interesting study, and the student will be re- warded not alone by the practical value of his discoveries, but by a deeper understanding of nature and her works. Canada’s Activity in Aeronautics OME months ago Canada bought ten airplanes. There were several reasons why she needed those planes. In the first place, some were for patrolling the great forests; some were to be used in cooperation with the Northwest Mounted Police. Also. a transportation and freight line was projected between Edmonton, Great Slave Lake, and Fort Nor- man. Oil had recently been discovered in that region and it was in an- ticipation of the rush of pros- pectors that the air route was planned. Here is just one instance of what the airplanes will mean to certain parts of Canada, or for that mat- ter, to any country where the railroad has not yet penetrated: with dog team or canoe the trip from Moose Factory to Cochrane took from three to six weeks; by airplane it took two hours!

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Ses tamer lige

GIRL I RUE TE 1 AE a eC IE RM

Popular Science Monthly Creating Steam by Electricity Though the electric boiler has been perfected for industrial use, it is practicable only where the cost of fuel is exceptionally high By Raymond Francis Yates

F we had a heavy electric current at our disposal and caused it to pass through a container of water, the temperature of the water would be raised to the boiling-point. The current would be led in and out of the water with two carbon electrodes. An electric boiler working on this principle has been perfected in Switzerland. We must understand at the outset that these electric

Electric boilers are taking the place of fuel-fired boilers in Switzerland, where the cost of coal is prohibitive. The new electric boiler shows an effi- ciency of 95.7 per cent. producing unit it is far more efficient than the conventional form of boiler. It can produce as much as 1200 pounds of steam in a single hour with a power consumption of only 146 kilowatt hours. As a steam- the plant is not operating, the turbine is used to drive a powerful electric gener- ator that supplies current to the electric boiler. Steam is generated in the boiler, and it flows from this point into the two storage boilers shown at the right side of the picture. These boilers are thermally insulated, and the stored steam is pre- vented from condensing until it is used the next day. These boilers have an enor-

boilers are not used for general power purposes. That would not be economical, since the transformation of electric power to steam power is always carried out with considerable loss. It is profitable to employ the electric boiler only where steam is used for certain indus- trial operations and where the cost of fuel is exceptionally high. What Is an Electric Boiler? A study of the electric boiler illus- trated at the bottom of this page will give you a very good idea of its general construction and working features. Two heavy carbon electrodes are sus- pended in the water, and these are connected with the electric power line. The heavy current, in passing from one electrode to the other paratus automatically adjusts the water-level for a definite degree of steam production. A small electrically driven pump supplies the boiler with water. The drawing on the opposite page shows a typical installation where a single electric boiler is used to supply steam to a factory. This factory, which is located in Switzerland, ob- tains its power from a canal. The water from the canal is allowed to pass through a water turbine, and this turns a long line-shaft to which the machinery in the plant is belted. The line-shaft is provided with a large clutch, which may be used to throw the turbine out of connection. During the night, when the rest of

mous. storing capacity. They can withstand a maxi- mum pressure of 18 atmospheres (265 pounds). The steam that ac- cumulates in the storage boilers dur- ing the night is sufficient to supply the plant the next day. A battery of the fuel-burning boilers is included in the equipment of the plant. These are used when the water in the canal is low or when the canal is emptied for cleaning purposes. In an emergency of this nature the stand-by boilers are started. They generated steam for the steam-engine shown on page 381. Steam-Storage Boilers Are New The electric boiler will probably never come into general use for power purposes, but it is finding

through the water, raises the temperature of the water to the boiling-point. This electric steam gen- erator or boiler is capable of producing 1200 pounds of steam an hour when the voltage of the current is 500 and the current strength 380 amperes. A very good quality of steam is produced that has a water content of only 3 per cent. Ordinary boilers produce steam with a water content as high as 5 and 10 per cent. The efficiency of the generator is 95.7 per cent. The quantity of steam produced is easily regulated by adjusting the water- level. The lower the water- level becomes, the higher the current density at the electrodes. This naturally increases the current con- sumption and evaporates more water. A simple ap- RHEOSTA , the electric power line. perature to the boiling-point ELECTRIC id BOILER

In the electric boiler two heavy carbon electrodes are suspended in the water, and these are connected with The current raises the tem- 30 wide application for special purposes such as the one here outlined. Here in America, where we have plenty of fuel for all purposes, there is no need that can be filled by its use. The steam-storage boilers used with the electric steam- boiler are especially inter- esting. They represent a departure in steam engi- neering. They have an ef- ficiency of 83 per cent over a twenty-four-hour period. The total capacity of the storage boilers in thermal units is 4,000,000. <A total pressure of 12 atmospheres may be reached with per- fect safety as a normal work- ing load. This may be the initial pressure of the boilers when the day’s work is started. At the end of the day the steam pressure falls to 2.5 atmospheres.

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ee eee ee August, 19%1 ELECTRIC BOILER BP STEAM UNE TO DISTRIBUTOR STEAM LINE 7O ENGINE SFEAM LINE FROM BOILE® The New Boiler in which Steam Is Gideneied by Electricity This shows how the electric boiler is used to supply steam for manufacturing-process purposes. When the machinery of the plant is idle during the night, the water turbine drives an electric gen- erator that supplies current to the electric boiler. The boiler, in turn, feeds steam to two large storage boilers, which supply the factory needs the next day. The electric boiler is capable of producing as much as 1200 pounds of steam an hour when work- ing at full capacity

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Cty we ont ee eee pa ae ee t Popular Science Monthly INDICATORS ERATED i: cap rt COIN-OPERATED BS DELIVERY DOORS iSM The food is placed on shelves in a revolving drum by an attendant. When you put your nickel in the slot, the glass door in front of the food opens, you lift out the food, and carry it to your table Slot-Machines Deliver Your Food ROP a nickel in the slot, and the glass door opens in front of the piece of pie you covet—such is the sys- tem in the wait-on-yourself restaurants that grow more popular every day. There are little glass doors in all four walls of the restaurant, and behind them are plates of food. You find the dish you want, and drop the required number of nickels in the slot alongside of it. The door opens and you take out your dish—no waiting for waiters and no tipping. But how about the other side of the wall? The picture above shows it in detail. The food is. placed on shelves in small revolving drums by an attend- ant who keeps a close watch on his particular section of wall. The drums food are kept hot. run through each drum, and the drum itself has a double wall that keeps the heat in. Hot drinks are kept in tanks. When you insert your nickel in the coffee slot, out comes a portion of cream, and then the coffee—exactly a are then swung around so that the food faces front. Suppose you want some ice-cream. Will it be sufficiently hard and cold after remaining in its compartment, for, perhaps, an hour? Yes; the ice- cream and cold-drink drums are kept cool by means of hollow jackets in which cold brine flows. continually pumped jackets. The brine is through the Similarly, drums that contain hot Gas-heated pipes Electrifying Water to Give It Sparkle OU can make plain water cupful. When your cup is filled, the mech- anism automatically stops the flow of the liquid. oo Virtually none of ; the cooking is done in the restaurants. There is a central bakery that supplies a dozen restaurants. The food is carried in huge — automobile trucks to A motor pumps a“ 3 BRINE PIPES FROM PUMP 2 cold brine the various restau- through the rants. drum Wear Lead to Avoid Radium Dangers HOSE who work with radium should wear lead armor and spectacles containing salts of lead, taste like champagne if you | charge it with electricity while you drink it. How is this done? The picture to the right shows a new electrical device for the purpose. The apparatus consists of a small circular tank that contains an electric cell from which two electrodes extend. One electrode is placed in the glass of water and the other is pressed against the drinker’s cheek. A slight current passes through ELECTRODE a PRESSING ON CHEEK ‘ ad £ ™~ UID the water and gives it a sparkle that is reminiscent of the days of sparkling wines. ciRope jj } \y \ according to Dr. Béclére, one of the leading radium experts of France. Thus protected, radium operators will escape many of the dangers accompanying its use. The injurious radium rays will pass through such substances as wood, but not through lead. Dr. Béclére also advises radium-users to employ instruments when work- ing with radium salts; the salts should never be touched with the hands. Radium has a ravaging effect on the marrow of the bones and on the spleen; its victim suddenly If a slight electric current passes through water when you are drinking it, it will taste like old-time bubbly champagne 32 develops pernicious anemia, a disease that is almost impossible to cure.

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rs am nd ad, the ce. ors ers vill as Dr. ers rk- alts the ,on on niy c ible August, 1921 ‘Will a Ten-Mile Dam Change Canada’s Climate? Plugging Belle Isle strait might warm New England also By Walter Noble Burns 74 The Gulf Stream, that beneficent body of water that comes up from the - gulf of Mexico, blanket- ing the coast of the United States, when it reaches New England current, which is strong enough to elbow it out ging the strait of Belle Isle, _ between New- foundland and Labra- dor, with’a wall of solid masonry, and forcing the Labrador current back. This, they de- clare, would’ make the climate of Canada and New England like that of the Carolinas channel separating Newfound- land from Labrador, is a hole in the wall of the Atlantic seaboard that is mainly responsible for the bleak winter climate of eastern Canada. Plug this hole, scientists declare, and eastern Canada and New England ‘would have a climate as mild and de- lightful-as that of the Carolinas. . Such a dam -would cost about ten million dollars. It would require the placing. of. a solid strip of stone and concrete. ten: miles in length. - The sr strait of Belle Isle, a narrow pe strip or dam.would be about fifty feet - wide and it would contain no less than 75,000,000 ,cubic feet of building ma- terial. This would be the equivalent 6f some 18,000,000 tons of stone and concrete. The railroad, which would be placed along the top of the dam, could be used- to transport the ma- terials, and .it would be extended as the dam projected itself into the strait. The engineers might start operations from both shores and meet in the center. Would Shorten Trip to Europe A group of British capitalists have asked concessions from the Canadian government to build a railway from Quebec to St. Johns, Newfoundland. The road would run along the north shore of the St. Lawrence river and the gulf of St. Lawrence, cross the strait of Belle Isle by the dam, and traverse Newfoundland to St. Johns on its southeastern seaboard. - Bzitish en- gineers have surveyed the route and reported on the feasibility and cost of the dam. The road would make St. Johns one of the great shipping meets the cold Labrador Ne into the Atlantic Sp puoson “4g @ Engineers are consider- ing the project of plug- NORTH AMERICA £-% ; : SPITZBERGE pg 32 GREENLAND \ P sD bis ul } Sih Ml i di ne yy points for Canadian export trade and would materially shorten the voyage to Europe. From St. Johns to Liver- pool is a thousand miles less than from New York to Liverpool. Canada has not yet announced its decision in the matter. Construction of the railway need not necessarily involve a change of climate. If a por- tion of the dam were built in the form of a bridge to permit the -flow of water through it, there would be no climate transformation. To change the climate, the hole must be plugged tightly. ; The dam would block the Labrador current from flowing into the gulf of St. Lawrence. The Labrador current has its origin in the Arctic ocean. Sweeping down from the frozen north through Baffin bay and Davis strait, it pours westward through the strait of Belle Isle to circulate about the gulf of St. Lawrence and bathe in frigidity all the shores and islands at that spacious arm of the sea. Passing out into the Atlantic again through Cabot strait, which separates Newfoundland from Cape Breton island, it turns southward and hugs the coast of Nova Scotia and New England. The Labrador current is the domi- nant factor in molding the climate of eastern Newfoundland, Quebec, Prince Edward island, New Brunswick, Nova Scotia, and the New England states. It makes the summers cool and pleas- ant, but it adds to the already severe rigors of the northern winter. It affects not only climate but business. With the dam obstructing its pas- sage through Belle Isle strait, the Labrador current would be forced out into the Atlantic ocean. What would 33 become.of it out there is a matter of speculation. The pressure of water flowing up from the south, the en- gineers declare, eventually would force it in.a giant curve back into the Arctic in the region of Spitzbergen. But its icy flood would no longer wash the shores of Canada and New England: the engineers say that, with the Lab- rador current diverted eastward, the Gulf Stream would swing in against the northern coasts. The Warm Gulf Stream After leaving the gulf of Mexico through Florida straits, the Gulf Stream turns northward and blankets the coast of the United States and keeps it warm till it reaches the lati- tude of New England. There it meets the Labrador current pushing south. The meeting is like that between a frosty old curmudgeon and some genial youth. The Labrador current holds frigid: possession of the coast, and, turning a cold shoulder to the interloper from the south, elbows it out into the ocean. The Gulf Stream continues northward to Newfound- land, and finally shears off northeast- ward, carrying its burden of warmth to England and western Europe. The Gulf Stream makes the climate of England what it is. Since climates mold the character of a people, their political fortunes, and industrial des- tinies, who will say that the Gulf Stream has not had a share in laying the foundations of the British Empire? Without it, at any rate, England would be as cold, and possibly as desolate, as Labrador. The engineers figure that, with the

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Labrador current diverted eastward, the Gulf Stream would wash all the coasts of New England, New Bruns- wick, and Nova Scotia, and, sweeping through Cabot strait, bathe with its genial flood all the coasts and islands of the gulf of St. Lawrence. It, after a run of several thousand miles across the ocean, with icebergs-melting along its northern rim, the Gulf Stream still has enough caloric to make the climate of such a northern country as England temperate and livable, how much greater would its effect be in amelio- rating the climate of Canada and New England? Will the Ocean Obey? The scheme of the engineers sounds perfectly plausible. Replace one ocean current with another and—presto!— you have a new climate. But will these mighty ocean currents obey the behests of these human pygmies essaying to direct their courses? Will they “‘stay put’? Here the problem begins to cloud with skeptic doubts. What assurance is there that the Lab- rador current, blocked out of the strait of Belle Isle, would not flow down the eastern side of Newfound- land and gain an entrance into the gulf of St. Lawrence by Cabot strait? If the Labrador current, as the en- gineers say, should go off into mid- Atlantic and lose. itself, is it certain that the Gulf Stream, in answer to the relieved pressure, would draw in its climate-transforming flood against the continent? Then again, suppose it behaved exactly as the engineers say it would, would its diverted waters ever again find their way across the ocean to England? Is there not a chance that, while the Gulf Stream is replacing-the Labrador current on American shores, the Labrador current, diverted east- ward, would envelop the British Isles? * region of the Great Lakes: of the Gulf Stream on the- eastern Popular Science Monthly The tremendous project is part of a plan for the construction of a new Canadian railroad, which needs a bridge to connect Newfoundland with Labrador While the climate of eastern Canada is being changed to that of Virginia, is there not a possibility that the climate of England would be changed to that of Labrador? These disturbing ques- tions are answered by the engineers in the negative,-but there are other per- sons not quite so sure. If the scien- tists ever had had any previous experi- ence in juggling ocean currents, the situation might seem less enigmatical. Granting, for the sake of argument, that the theory of the engineers would carry through, there is no reason to doubt that the climate of Canada would be tempered as far inland as the The effect coast would’ duplicate that of -the ‘Japanese current on the western. The Where We Injure Ourselves Most HIS drawing shows the results* © obtained by a careful analysis. of:~ more than eighteen thousand injuries. It shows at a glance where we injure ourselves most. The hands and fingers are injured most, and this is natural) since we use our hands more than any other part of the body. After the hands come the eyes—and this is more serious. The body, extending from _ the* shoulders to the trunk, receives ‘only’ 7.3 per cent of the total injuries. -The eyes represent only a very small: per- centage of the area of the body, yet they receive many more injuries due, in most cases, to flying particles’in industries that use metal. Many‘of the accidents caused in this way have been prevented in the last few years by the use of heavy goggles. Vulnerable parts of the body. This diagram was prepared from a study of more than 18,000 accidents 34 Japanese current makes the coast of British Columbia a land of midwinter flowers, and distributes its largess. of mildness on the wings of the chinook winds as far inland as the transmon- tane prairies of Alberta. Southern Alberta is in the same latitude as: Montreal and Quebec; but, while the: St. Lawrence river is locked with ice; cattle and livestock of all kinds are: browsing in Alberta pastures and Alberta farmers are preparing their land for the summer harvest. Changes that Would Arise If-the wall of masonry across the strait of Belle Isle would change the climate, it would also alter the agri- cultural and industrial destinies of eastern Canada. The fertile soil of Ontario,- Quebec, New Brunswick, and Nova Scotia, already regions of teem- ing agricultural wealth, would become familiar with new crops. Vast areas now covered with primeval forests sweeping down from the northern hinterland would be cleared and trans- formed into farms. The value of the land in the maritime provinces and the - valleys of the St. Lawrence and the Ottawa would be enhanced by biltions of dollars. New industries would spring up os meet the changed conditions. New wealth would swarm in, seeking in- vestments. Immigration would pour in. New cities would arise. Popula- tion would increase enormously. Can- ada would soon become a competitor of the*United States in the markets of the world. Montreal would loom as the trade rival of New York and chal- lenge the commercial supremacy of the continent.

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August, 1921 The Climbing Weather Man — 1 THEN a young man enters the service of the government Weather Bureau, he is naturally possessed. with a desire to rise in the world. This laudable ambition is promptly gratified. . Not only are the offices of the Bureau commonly perched in the top stories of sky- scrapers, but the weather instruments that must be exposed ‘to the elements are located at still higher levels. A job that usually falls to the lot of the ‘‘cub” observer is that of watch- ing the anemometer. This instrument, together with the wind-vane, is installed at the summit ofa skele- ton steel tower some forty feet above the roof: It consists of four hemi- spherical cups, the revolu- tions of which indicate the velocity of the wind. Al- though the anemometer is connected electrically with registering apparatus in the office below, the dial attached to the instrument itself must be read at intervals in order to check the auto- matic: record. Moreover, anemome- ters need frequent oiling, and about once a month the regular instrument is removed for a thorough cleaning, an extra anemometer taking its place. Both agility and nerve are required for these operations. The New York city anemometer is 450 feet above the sidewalk. In Chicago, though the in- strument is not so high, it is located in close proximity to the mouth of a chimney that belches forth clouds of stifling smoke. Hence the Chicago weather man dons a gas-mask whenever he mounts the steel tower. Are Foghorns to Become Obsolete? NYBODY living near a seaport who has suffered from the nerve- racking many-toned fog- horns, will appreciate the equipping of harbors with wireless fog signals. This has been made pos- sible by the development of a new radio compass, by which a ship captain may determine his exact posi- tion instead of relying on whistles and foghorns. Agility and nerve are required for this weather man’s job of reading an anemometer on top of a skyscraper; he wears a mask for protection against smoke _ After draining the channel, it was deepened, and the creek was lined with concrete by a traveling form Lining a Creek with Concrete ORMS were used for deepening and lining with concrete a creek channel at Syracuse, New York. The channel was deepened, after being drained by a walking drag-line excavator. Five units made up the traveling form used for con- structing the side walls. Mounted on double-flanged wheels, each unit was fourteen feet in length. Three rigid cross-braced trusses made up the individual units of the forms. Attached to arms, sliding with the upper and.lower cord members of the trusses, were the steel. faces of the forms against which the concrete was de- posited. The face Sorms could be moved hcstadeiealbe to gain adjustments in desired positions. The movement and adjustment of the face forms was controlled by three jack-screws at each end of each truss. He Tastes Radio Messages AVE you ever placed the wires from a dry battery on your tongue? If you have, you will remem- ber that a peculiar “taste”? was pro- duced. This is often used as a test to For receiving radio messages in noisy places, two experimenters have evolved a method of reading radio by placing two electrodes on the tongue 35 ° determine whether or not there is any current left in a battery. The “‘taste”’ is caused by the electrolytic action of the current flowing through the mois- ture on the tongue. Dr. Alfred N. Goldsmith and Edward T. Dickey have experimented with a system of radio re- ception, using this tasting effect of the electric current. The system is not proposed for commercia! use, al- though it is possible that it may some day be cons sidered seriously where re- ceiving must be done in a noisy place. The currents in radio re- ceiving equipment are so weak that they would have no effect on the tongue. To overcome this prob- lem, the experimenters used a vacuum-tube amplifier that brought the value of the current up to a point where it would cause the proper physiological effect. Two. -silver electrodes mounted on a piece of hard ru are placed in the mouth. When these are laid on the tongue, the cur- rent flows across and causes the stinging sensation.

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ees oa « on Penn grweimen Tok + ateane te parton w wart sates BaD cone Fae = es 2 martes " > Pon snecienenteinipanate 25 f eapetenn ae Rho" F wi eae Ss ee or as Popular Science Monthly Chain and Padiock for the Shoe-Lace minha tain may break, be- come knotted, or untied. The thought caused an English- woman so much worry that she could no longer enjoy her square-toed oxfords. But she was not to be daunted! She bought two chains, two padlocks, and two keys. Ripping out her untrust- worthy laces, she inserted the chains in their place. Next, she locked: the ends together with her padlocks and added the keys to her key-ring—a simple solu- tion of a difficult problem. There is one objection to this system. The woman must have her keys in order to take off her | The Oil-Saving Can with a Flexible Spout om sells for eighty cents a gallon,-and there is no use crying over spilled oil. With the aid of this little can, which is equipped with a flexible spout, all of the oil used-on the car may be put where it belongs ground. A flexible piece of metal tub- ing is soldered to the spout of the can and this may be used to direct the oil to any out-of-the- cessible place. The can holds two quarts, and there is no’excuse for wasting a . drop of ‘oil: when the flexible spout is used. A can of this shoes. Suppose she should lose the keys? Then she would have - to send for a locksmith. You Can Now Have Eyelashes to Order yaar a few must suffer for the good of many has once more been proved. The beauty doctor shown below specializes in complexions. He injects color under the skin of pale-faced women, and makes them happy. One day he tried out a new pigment. Alas! Hair grew on the pet where the pig- ment was injected! The’ beauty doctor immediately branched out into the eyelash business. He injects that same pigment in the lids of women’s eyes to-day, and has become famous as an eyelash-grower. It is to be hoped that the purveyor of beauty was able to help the ladies who were the sufferers in this otherwise successful experiment. How Wood Is Tested for Strength OOD is still used in constructional work. While the engineer knows exactly the weight a steel beam of certain dimensions will sustain, he has very little data to help him figure the strength of wooden beams and rafters. The United States Forest Products Laboratory has designed and built a machine that will test the tensile, com- pressive, and bending strength of wood. It is called a vertical screw-testing machine, and with it one is able to exert a pressure of one million pounds. It can test a beam or log thirty feet in length. This machine will make available a mass of figures that will be of great benefit to the engineering sciences. Steel and other building materials have been tested by special machinery for a long time, but engineers have just begun to turn their attention to the testing of the differ- ent woods. Some very interesting data have been accumulated. nature has long been needed. All motorists owe the inventor a rising vote of thanks. oes Ironing without Touching the Iron paRon with your feet; they do not ite as rapidly as your hands. But how can this be done, you ask. There is now an electric ironing appara- tus that not only heats the iron, but moves it back and forth across the ironing-board; you merely step on a foot-pedal to start the iron in motion. With your hands you guide the cloth, much as you do when you are using a sewing-machine. Of course, an iron of this sort can be used only on laundry pieces that are nearly or quite flat. For example, you could not iron a blouse or ruffled summer dress with - Besides, it is a ' this mechanical iron. factory machine, which can be profitably installed only when square miles of fabric are to be ironed. a | instead of spilling it on the © way bearing or otherwise inac- © YT: Soa: tes ne

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August, 1921 How to Keep the Golf-Ball Clean GOOD clean white golf-ball is a ball that can be seen easily. It is especially useful for poor players who are not able to keep the ball on the green. When it gets into the deep grass it can be seen very easily. Below is a little golf-ball cleaner that will fit in the vest pocket. A small sponge is first used to wet the ball. Then it is pressed on and revolved against a small rubber mat that is contained in the other half of the container. This little device will make a welcome addition to any golf-player’s outfit, A New Toothbrush . Every Day N toothbrushes the latest idea provides a’ new brush every time you wash your teeth. ° Sete In ‘the- new invention the handle and the brush come separately. The brushes, made of a vegetable fiber, come joined together, wrapped in a sanitary package. The user breaks off a brush as often as he has need of one, and fits it into a depression in the handle. After once using, the brush is thrown away. Besides the enormous ad- vantage of cleanliness, its makers claim for it that the short bristles and small size as a clean ball is always more easily seen than a dirty one. Harvesting Sweet-Clover Seed PROM Springfield, Illinois, comes a man who has invented a machine for har- vesting sweet-clover seed, without cutting the plants, in the field. One man drives while another tends to the screening and sacking. The machine is carried by two wheels, while the end of the tongue is supported by a caster wheel to facilitate turning at corners. A chain sprocket on the large axle drives an overhead shaft bearing four large paddles or threshing-wheels. Parting guides compact the stalks as they are drawn through fin-shaped paddles. These notched paddles mesh loosely. As the stalks are drawn through, they are bent into angles while the seed is beaten off. The seeds drop into conveyors that carry them to a bin. A swath nine feet wide is covered by the machine. The Leemnat Submarine Carries a Twelve-Inch Gun ‘TBs is a new British battleship of the deep. She is certainly a wicked piece of fighting steel with her twelve- inch- gun. ‘The gun is one-that can be used for “all-around”: purposes.” It can be elevated to fight off airplanes, or it can be leveled at another submarine. The outer surface of the big gun is made waterproof and the muzzle is tightly plugged before the ship submerges. The largest gun carried by a United States submarine has a three-inch bore. | The gun of the British boat may’be fired while the deck of the vessel is submerged. It is necessary to leave only the peri- scope above the water. The new vessel is two hundred feet long and twenty feet wide. The mounting of guns on submarine decks greatly interferes with the speed of the craft. In fact, every object on the deck offers resistance to the movement of the vessel when it is under water. But what is lost in one way is gained in another. Guns on the deck of a submarine heighten its ability to protect itself and to offer assist- ance to the fleet during conflict. One advantage of the smaller gun is that it can be made to disappear into the deck when the vessel is ready to submerge, thus enabling the submarine to attain its highest speed, either away from retali- atory danger, or to a more advantageous spot to continue its attack upon the enemy. of the brush enable it to reach every part of the teeth with ease. Gather Corn the Cheaper Way Mo? farmers know what an expensive matter harvesting corn is, with the cutter and blower at the silo and the harvester in the field. I. J. Mathews, of Indiana, has adopted another method, one that effects a saving of forty cents a ton on his corn crop. He attaches a corn-harvester to a cutter, the whole being run by a gasoline engine. The stalks are taken up by conveyor chains and fed to the cutter with the butts first. After the corn is cut, it is fed to a wagon. With this combination of harvester and cutter, trips to the silo need not be made as frequently as in the old way. This allows the corn in the silo longer to settle and thus permits larger deposits of grain. Three horses are required to draw this outfit over the field.

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Popular Science Monthly

Making the Repair © of Faucets Easy (eet excitement per- vades the house when a faucet cannot be turned off. There is much hurry- ing to find the water-valve in the cellar. Then, when this is accomplished, the entire house is waterless. A French inventor uses a faucet that automatically cuts off the water when it is removed from the pipe. The end of the faucet rests against a small trapdoor in the pipe. When the faucet is removed, the door is left free to close and the pres- sure of the water at the other end keeps it in place. The water is automatic- ally turned on when the faucet is repaired.

Dried Caterpillars’ as Food NDIANS in the Mono. lake district of Cali- fornia regard’ as a great delicacy- a-certain species of caterpillar, ‘which they call “‘pe-aggie.”’ They — dig trenches around the base of trees, the -vertical sides of which prevent caterpillars that. stray in from getting out. After gathering quanti- ties of the caterpillars, the - Indians dry them in hot sand. Then the sand is re- moved, and the caterpillars are spread on the ground for two days; after which they are kept in sacks until needed. J. M. Aldrich, of the United States National Mu- seum, has partaken of the “‘delicacy,”’ and does not

SELF-CLOSING You Can Carry this Washer in a Trunk NE glance at the picture below will inform you that the six-pound electric washerette has arrived, made especially for those who live in kitchenette apartments. Its operation is done with little noise, and it can be placed in a bathtub or across a kitchen sink or wash-bowl. The washerette has been designed to meet the demand for a small washer that will not injure delicate fabrics, such as fine blouses, silk stockings, and undergarments, as well as all articles of baby’s clothing. The machine is driven by a small water- motor. It is necessary merely to turn on the water’and watch it work.

‘the help of tongs and tweezers.

Where the Passaic River Flows into a Crack HE Passaic river, near the silk-mills in Paterson, New Jersey, was once con- sidered as a possible source to furnish one hundred million gallons of water a day to New York city. An enormous amount of power is gener- ated at the Paterson falls. One curious feature that makes this waterfall different from others is a geologic peculiarity. Flow- ing northeast, the river appears to end suddenly. A close view shows that it turns abruptly toward the south and pours into a deep crevice in the basaltic rock. There is a sheer fall of seventy- two feet, and a part of the chasm into which the water pours is only five or six feet across. During the flood season a force of some two million tons is hurled daily at the basalt obstruction. How Did the Ship Get Inside? Aarne of us have seen ships in bottles. But that is not,the interesting point. The point is. how did the ship get in the bottle? 3 It is no great secret. Contrary to the general belief, the bottle was not .blown around the ship. No; the patience of a very careful workman. is.required. . First, he cuts out the necessary pieces to make his ship, then he inserts them into their proper places in the ‘bottle. In fact, the ship is built_up inside the bottle with The sails are first inserted in the. bottle and are then pulled erect by strings...

regard the flavor so highly as do the Indians.

Bayonets Make Good Wood-Cleavers oe there is no military use for the sword bayonet now, inventors are ex- erting their ingenuity to convert it into a useful and harmless implement. The accompanying illustration shows an ingenious attachment produced from a sword. It is a wood-cleaver, which a Ger- man firm recently exhibited at the Frank- fort fair. The sheath comprises a number of notches for holding the sticks, the sword being fixed in hinges at one of its ends. ' It is an excellent device for chopping wood, there being no risk of harming one’s fingers. The wood-cleaver is screwed fast to a table or a chair.

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Respiration Is Measured with This Apparatus HE muzzlelike mask worn by the man in the picture is an apparatus invented by Dr. J. L. Pech, a French practitioner, for measuring with exactness the volume of air taken in and expelled during the process of respiration. He believes that the instrument has as much diagnostic value as the stethoscope. The mask, which can be thoroughly sterilized, consists of a metal cone, shaped to fit over the nose and mouth. Airtight contact is insured by an elastic cushion of rubber. The metallic cone is a one-way valve, through. which the air enters, and is con- nected with a manometer by means of a rubber tube. Mothering 1500 Chicks A BROODER that gives chicks just the amount of heat they need is shown below. The fuel, a low-grade petroleum oil, is kept in the tank at the top of the heater. As many as fifteen hundred chicks may find comfort and warmth around this stove at one time. The brooder keeps them at the tempera- ture a mother would ‘keep them if their mother had been a hen and not an incu- bator. The temperature of a hen is about 106° F., but it has not been found neces- sary to keep the temperature as high as this in the brooder coop. A uniform temperature is maintained automatically by a water-regulator that controls the flow of the oil from the tank to the burner.

Getting More Wear Out.of. Shoes ee ti ~ 2 * fe SHOES < do’ not’ wear’ ‘as’ long. as they: = Ls ¥ we should} especially workingmen’s shoes. Metal shields will prolong the useful life of noise they make when they come in contact with the pavement. There is a distinct click, click, click that is not pleasant to hear. : However, if the wearer is willing to overlook the disadvantage of the noise, these iron shields will certainly add several weeks at least to the life of his shoes. The shields protect the parts that are sure to wear out-first—the front of the sole and the heels.. They may be bought for a few cents and they are attached to the shoe with very little trouble.

No More Arguments About the Dish«Washing ONNECT this dish-washer with the faucet and let it do your dish-washing for you. This will do a lot toward saving time, so that the household members can get to the movies in time to see the first show. A small water-motor is arranged inside the device, and this whirls two nozzles around, spraying the dirty dishes with clean water. The dishes are held in a wire tray above the whirling nozzles, the water reaching every dish. It is claimed for this washer that dishes for a family of six can be washed in three minutes, after being given a preliminary. scraping.

‘shoes, but ‘most persons do not like the /jjjum

You May Hear Yourself as Others Hear You H=*48 yourself as others hear you; this is a good motto for would-be elocu- tionists. And it can easily be done by means of the ladderlike device shown above. As the woman speaks, her voice rumbles through the various tubes and comes out through one of the tubes above her. Not only is her own voice plainly heard, but it is also amplified so that all the defects in her pronunciation stand out. The tubes in the case are made of cardboard and are sealed at the closed ends with paper. This device simply projects your voice into space and then brings it back again to your ear. It is a mechanical echo. A Tiering-Truck Becomes a Hoist ELOW -is shown a clever stunt of a machine-shop foreman. A small elec- trically driven tiering-truck is pressed into service in placing a heavy die on a large punch-press. The die weighs several hun- dred pounds, far too heavy for the-men to lift. The truck is called into use and the die is loaded on to the platform. The motor is switched on, and up goes the die to the level of the press. Then it is simply a matter of sliding the die under the punch and bolting it down. This is only one of many uses that a tiering machine may be put to besides stacking. Heavy pieces of work may also be placed in lathes and boring-mills in the same manner.

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SG RRR Pie teow “Eres Lp oe penn oe AS eR es go See taamenrtag Sere =: ES Tes eS Learn How to Increase the Life of Your Shoes aged the simple formula below and you will be able to cut several dollars off your shoe bill this year. The use of oil or grease not only makes leather wear longer, but it renders it softer and more pliable. When leather is softened it is not so apt to crack. A properly greased shoe is also waterproof. . Before shoes are oiled or greased, they should be carefully brushed How Glare Fatigues the Eye ie more people could be made to | realize the value of correct illumination, opticians would not be so busy doctoring abused eyes. Look at the photograph below showing eyes under proper illumi- nation and under direct glare. Note the difference. Notice the shrinkage of the pupil of the eye subject to glare. The condition of the entire eyeball is abnormal. The other eye appears rested and normal. This comes from the proper diffusion of light by the indirect method of illumination. The proper diffusion and distribution of light in a room is brought about by the use of the proper kind of.a reflector. With in- direct illumination the light is first re- flected against a white ceiling and from this it is reflected into the room. This pre- vents a concentration of the rays. Popular Science Monthty etait, Would You Take the Blisters Out of Grass-Trimming ? oT gta y as a man may enjoy and feel a pride in taking care of his own house and grounds, anything that will help to take the hard work out of cutting the grass and keeping it in order is certainly wel- comed by him if it is his lot to keep the grounds looking right. After the lawn-mower is used, it is always necessary to apply the grass-shears in order to get into the corners and warmed in an oven for a few minutes. To apply the warm oil or grease, use a cotton swab or a soft piece of flannel. Then rub the oil well in the leather with the palm of the hand, taking special care to -work the grease into the seam where the sole is joined to the upper. ‘Tallow or wool grease are ihe useful for this purpose. that the clumsy lawn-mower can not reach, alsa to trim the edges, and of course bushes and hedge. That is where these new shears:came in handy. They. are made to fit the human hand; unlike most of their forerunners. They prevent fatigue. and painful blistering and they cut the grass just as well as the uncomfortable kind. Making the Air Propeller Smaller and Faster OUND waves travel at about 1100 feet asecond. Here is a new type of pro- peller that can be driven at a tip speed of 1500 feet a second. The sound it produces is far higher in pitch than that of any air- plane propeller, and its tip speed is higher than has ever been attained experiment- ally, the previous record being about 900 feet a second. Beyond that speed the pro- peller ordinarily loses its efficiency and ceases to exert any thrust, or “pulling” force upon the air. With this aluminum model at a tip speed of 1500, representing a shaft velocity of 7200 revolutions a minute, there is a pulling force or “thrust’’ of 200 pounds. The new propeller is the invention of S. A. Reed, an expert mechanical engineer, who is conducting his experiments at the Curtiss plant. When the tip speed of a propeller reaches 1000 feet a second, its centrifugal speed is 16,000 times the weight of any object at its tip. Every particle of the material at its tip is thus tending to be hurled out at a pull equal to 16,000 times the weight of the particle. This means a tension of about 1000 pounds on the pro- peller, tending to stretch it out straight. The motor used in the experiments devel- oped 100 horsepower. The propeller is four feet in diameter, and is very thin and sharp at its edge. From these experiments it is expected to devise a propeller of suitable material half the size of those now in use. To obtain high speed from the engine without the use of reduction gears, thus to make use of the engine at its best speed, is the ultimate end in view. This invention can also be applied to marine engines. Sheep Under the Electric Clipper YN sheep are shorn by hand with scissors, they are frequently injured. By employing an electrically driven clipper, the animals are spared pain and injury, and the wool is removed more evenly and more rapidly than could be done by hand shear- ing. The illustration shows the method em- ployed in the shearing. The sheep is placed on a table resting on trestles and the feet of the animal are strapped to a station- ary rod provided for that purpose, so that it cannot roll over or make any other motion that might interfere with the work. The clipper, which is similar in*con- struction to that used by barbers, has a number of cutters arranged like the teeth of a comb, and obtains a rapid oscillating movement by an eccentric gear driven by a small motor.

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August, 1921 When a Blaze Starts | & the Bell Rings IRE-ALARMS_ ‘-° must function without fail. Let the temperature of a room reach 165 degrees and this fire-alarm will attract attention by its noise. The device is controlled by a small fusible link made of a metal that has a very low melting-point. Melt- ing at low temperature sounds the alarm, and en- ables those present to catch the fire before it has reached a dangerous stage. It may be used again by simply inserting another fusible link. These links are so accurate that the govern- ment has used them to test thermometers. Cotton from Airplane ‘‘Dope’”’ HE, heavy coating of varnish, or 4 “dope,” on airplane wings contains what might be called “liquid cotton.” To prove this, one can take a little of the dope in a test-tube and pour into it an equal amount of water. Immediately the cotton begins to form. It appears in natural fibers that can be taken out of the tube and woven into a fabric, or made into thread. Unless the fabric of the wing is absolutely dry when the liquid is put on it, the cotton will have a rough surface. The nitrated cellulose suffers a rapid reaction from water. Until it is thoroughly dry moisture must not reach the coated wing-surface. Cotton is seen forming in the center of test tube as water is poured in. Life on King’s Island HE Eskimo island, a rocky cliff that rises -above the surface of North Behring sea, build flimsy-looking structures balanced on poles and walled «with skins, for their: living- rooms. They* sleep in holes burrowed in ° the rock. °, wea United States coast-guard officers have found the huts warm even when the mer- cury registered below zero. Langley’s First Flying-Machine r the model-room of the Curtiss airplane factory at Garden City, Long Island, are many interesting miniatures of flying craft. Not the least so is that of Professor Langley’s first aerodrome, the replica of his first model which actually was flown with mechanical power. A. L. Tiiurston, who holds the model, has been responsible for many improvements in modern aircraft. Note the propeller in the side of the model. It was shaped to propel the craft through the waves of the air much in the manner of a “side-wheel” of an ancient river boat. It was this crude pioneer that inspired the Wright brothers to continue their own experiments. inhabitants of. King’s: “Pull‘the Trigger from ~~ the Inside a) NE inventor at least ““-is going to give the bandit a-run' for his money. This automatic — pistol, which has been invented by a member of the San Fran- “cisco Fire Department, is held under the armpit, and it may be fired without any suspicious move on the part of the person held up. A ‘small flexible. shaft - runs from the trigger down the inside of the coat sleeve. A button is placed at the end of the shaft, and when this is pressed with the fingers, the gun explodes. It is a sure-fire arrange- ment and a deadly aim may be made at close range. Making the Gas-Tank Safe BULLET-PROOF gasoline-tank for airplanes has not yet been: devised, but here is a tank into which numbers of machine-gun bullets can be shot without danger of the gasoline leaking out suffi- ciently to bring the airplane down in flames. The metal tank is covered with a jacket made of three-ply rubber. On the outside are several thicknesses of closely woven canvas. When a bullet cuts its way through the tank, the rubber automatically closes up the hole. There has, however, been devised an incendiary bullet containing phosphorus that undoes the complete utility of the rubber cover. It is now up to somebody to offset the effectiveness of the new bullet.

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a tenes } Ph a Et 3 - Popular Science Monthly Underground Roads and Elevated Speedways May Solve the World’s Worst Traffic Tangle PPROXIMATELY one third of A the half million motor-cars in New York state are registered from the city of New York. One hun- dred and sixty-five thousand cars roll along its streets every day. New York’s traffic problem is a peculiar one. The greater part of the city, the busiest part, at least, is located on the long, narrow island of Manhattan. There are a great num- ber of crosstown streets on the island, but very few up- and down-town streets. In fact, the busiest part of Manhattan has only fourteen up- and down-town streets. Traffic on four of these streets is interfered with by the presence of elevated railroads and street-car lines. The steel pillars of the elevated road structures greatly impede the progress of street traffic. During the rush hours of the day the north-and-south (up- and down-town) traffic is barely manageable. The main arteries are crowded to the limit and, with the present facilities, in a few years’ time it will be absolutely im- possible to keep them clear. Some- thing will have to be done. Although the new block system in use has done a great deal to alleviate the traffic conditions, the problem is not solved. Commissioner Enright’s Plan The widening of the streets has been considered, but, after a careful analysis of the present conditions, it was de- cided to abandon the idea. Police Commissioner Enright has suggested the plan that is roughly outlined in the sketch of Manhattan shown. He sug- gests that a speedway be built from Seventy-second street to the Battery along the west side of Manhattan island. This would be either an ele- vated or a subterranean. thoroughfare, and it would probably take its course along the present Ninth avenue. The Sixth avenue elevated structure would also be eliminated between Third and Fifty-ninth streets, and this thorough- fare would then be changed into a speedway. Second avenue, which runs up the east side of the island, would be changed to a_ speed- way. This would make three main arteries for traffic that would not be interfered with by vehicles bound across town. It is the crosstown traffic that prevents the free movement of uptown and downtown traffic at the present time. Fifth avenue is badly con- fic. ELEVATED STRUCTURE REMOVED LEAVING STREET CLEAR FOR VEHICULAR TRAFFIC By Raymond Francis Yates Illustrating Commissioner Enright’s suggestion to convert Ninth, Sixth, and Sec- ond avenues into speedways, to be used for one-way traffic during the rush hours gested all the day, and especially dur- ing the morning and evening rush hours. In the evening it is almost im- possible to handle the flood of vehicles. Broadway and Park avenues get their share of the traffic during these hours, at which time they are crowded to capacity. The establishment of other routes that would offer unrestricted movement would relieve these three 3 q js This shows how elevated railroads could be replaced by subways, thereby giving the street over to vehicular traf- The sketch at the right shows a subway for vehicles 42 streets of the present strain. If traffic could be distributed evenly between the fourteen streets that now run up- and down-town, the problem would not be quite so serious as it is now. Ele- vated structures on four of these streets prevent this, and it is natural that the vehicles take the central routes. If these elevated railroads were eliminated from the surface and subways built in their stead, the streets could be given over to the entire use of vehicular traffic. Dr. John Harriss, New York’s Deputy Police Com- missioner who installed the tower signal system on Fifth avenue, has made a new sug- gestion about handling traffic that is being considered very seriously. Sixth avenue, which already

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August, 1921 boasts of trolley-cars and* an ele- vated railroad, has been selected by. Dr. Harriss as a street in need of a second story. He suggests that a viaduct be built, starting at Fortieth street near the entrance to Bryant Park, and extending to Central Park at Fifty-ninth street. It will be on a level with the elevated rail- way and will accommodate both automobiles and pedestrians. Some Statistics It is feared, however, that _prop- — erty-owners will object to the build- ing of such a viaduct, believing that it will injure their business. . Dr. Harriss, on the contrary, thinks that it will do more good than harm. There is a space of forty feet on either side of the railway tracks, and this will:be. divided into a roadway and a sidewalk. A second-story entrance to the stores located on this street could be built on a level with the sidewalk. In regard to this traffic problem, Mr. D. L. Turner, chief engineer of the Transit Construction Commis- sion, says: “There are only about one hundred miles of up- and down- town streets to serve about three hundred and twenty-five miles. of cross-town streets. There are only eleven through up- and down-town Fp coy ny Fee “LIGHTS. - ‘ELEVATED xo}, Saale + + J Dr. Harriss, a New York Deputy Police Commissioner, would place this elevated street along Sixth avenue. This would parallel the elevated railroad on each side, and it could be arranged at the same height. Such a structure This is the way the Sixth avenue elevated railroad would look if the tracks were eliminated and pavement laid on the surface. Such roadways would be used for down-town traffic in the morning and for uptown traffic in the evening thoroughfares to serve approximately one hundred and fifty cross-town streets. In other words, there are nearly fourteen cross-town streets to one up-and-down street.” Mr. Turner has put the situation into figures, always more dramatic than mere words. With such a con- dition as he portrays, something will have to be done. Whether it be Commissioner Enright’s plan that is adopted or that of Deputy Police Com-. missioner Harriss, or some other yet unheard-of solution, New York will have to do something, and not be too long about it. avenue. Fifty-ninth street 42> St Sov SS” ST. 20" ST s 5. $3" eerie ee » = AVENUE Qn 6=A RAY IW) LU == a. would practically double the traffic capacity of this It would extend from Bryant. Park at Sixth avenue and Forty-second street to Central Park at

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8 tga TES ee he METEORIC Popular Science Monthly CLOUDS © Madern Publishing Company Drawing by Scriven Bolton How Meteoric Dust Gets into Our Atmosphere Our earth continually collides with great swarms of meteoric dust. As these particles dash into our atmos- phere at a speed of from ten to forty-five miles a second, they are immediately reduced to powder by-friction with the earth’s air, becoming visible as the particles are burnt at a height of from fifty to seventy miles. Thus we see the shooting star. This powder charges the upper air with cosmic dust, 44 which ultimately settles down on the earth. This is actually in part the ‘‘dust” that is the bane of the housewife. It is estimated that about forty million particles, or meteors, become entangled in the earth’s atmospheric net every day, and that, ground to powder, these add to the earth’s load two hundred tons in every twenty- four hours

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August, 1921

8 | a raised platform on which Two- Hundred Tons Added to the Earth Daily Shattered comets shower our planet with dust HERE is not a spot . on this globe that has not yielded what the housewife calls “dust.’’ It is found settling alike upon the white polar snows and on the Sa- hara desert, as well as on the decks of ocean-going ships. The earth is continually colliding with great swarms or clouds of dust and. small particles, ranging in size from a pin’s head to a walnut. In dashing into our atmosphere with a speed of from ten to forty-five miles a second, they are immediately rendered _ incandescent, and reduced to powder through friction with our air. This process of. dissolution produces the shooting star or meteor. Thus the debris, ‘or: powder, resulting from the continual destruction: of these masses, charges the upper air with cosmic dust, which ultimately settles down upon the earth. What Happens to the Dust The upper layers of our atmosphere are accordingly’ being continually charged ‘with magnetic meteoric: dust, which forms a continual addition of material—~-about two hundred © tons - daily--to the-earth’s load. It is esti- matéd:that.about forty millions of par- ticles; oF meteors, become entangled in By Scriven Bolton, F.R. A. S., M. B.A. A. the atmospheric net every day ia are ground to powder. An incalculable number of particles, of both organic and inorganic origin, are held in suspension. in our air. Attempts to detect meteoric dust that settles on the general surface of the ° ground are virtually. useless, owing to: the usual presence of contamination. Cosmic stony and metallic particles, however, are discovered in abundance in the bed of oceans, since the process ©’ of slow deposition continues uninter- ruptedly. These great dust shoals that the earth incessantly encounters are be- lieved to be the debris of disinte- grated comets. They have well timed tracks round the sun, and are dis- tributed completely along their orbits, thus forming great ellipses round the sun. Hence the earth, in crossing these paths on fixed dates every year, encounters these swarms. - Mutual attraction alone holds to- gether these huge dust-clouds, which are so very tenuitive that the gravity of. the planets remains undisturbed, and they become visible only as the constituent‘ particles: are burnt up in our atmosphere at a height of from fifty to beg ens presence in the air of solid particles and dust in question. «. Twilight. is nothing’ more nor less than a.reflection ‘of the sun’s light by. atmospheric vapors, and the; dust particles i in suspension... The outer layer of our atmosphere must be ‘greatly charged: with’ this ‘fine ‘cosmic “dust, and the afterglow. appears to be ; greatly: ‘increased ‘by. the precipitation ? of moisture on:these *particles’ as night approaches. The fact that.the earth encounters ‘great shoals ‘of dust in ‘October and November gives rise to the splendid afterglows in these months. Is ‘the Aurora Borealis Made af Dust? This meteoric dust is composed chiefly of iron, magnesium, manganese, ‘ carbon, nickel, copper, sulphur, phos- phorus, lead, thallium, and various silicates. Now, the spectrum of me- teoric dust is practically coincident with that of the aurora, or the North- ern Lights. Evidence appears to show that the aurora finds its sole origin in this dust, which is of a magnetic nature. If is stated on the: highest authority ‘that a display of-the aurora signifies a shoal of dust. particles trayel- ing at a< <trémendous, rate’ ‘through the upper part of our atmésphere. What Is the Scoresby? | N instrument known as_ the “gcoresby is used at the United States Naval Observatory at Washing- ton for teaching future navigators how to compensate for the . deviation of the compass. magnetized iron are placed. They rep-. resent the combined effectiof the mag- netizing influences © on “board ‘ship. These magnets spree the Fompame

This deviation is caused by the steel and iron in the whole structure of a battle- ship. The scoresby consists of a compass and binnacle set on a pivot so that the magnetic bearing of an artificial sun, which is a part of the appara- tus, remains always the same. The “sun” is an electric light, in a circular frame, near the ceiling in a corner of the instruction room. Its beams fall directly on the instrument. The compass and binnacle are mounted on a@ support that can be re- volved on a track to any position corresponding to a hew direction in the ship’s course. In front of the compass is

variously shaped pieces of

The scoresby teaches students of navigation how to compensate for the deviation of the compass, due to the presence of iron and steel in. ships 45 needle a ddfinite ‘number: of . degrees from ~ magrietic «ziorth, according to their. strength and position. . The problem i is to ‘determine how great the deflection is from ‘the mag- netic north, and ‘how to com- pensate for it. Compensation - ‘for’ deflec- tion is made as, follows: ’ The apparent position of : the sun is observed and read. This reading is compared with the magnetic bearing of the sun, whichis obtained ‘for any position of the ship from a’ book of:tables. The difference. between the two bearings is the amount of deviation of the compass. By means of a set of small mag- under the compass, which can be moved closer to or farther from the compass, the needle is forced to swing around until the apparent bearing and the magnetic bearing coincide. The de- flection is then compensated for, and the compass reads correctly. The splendor of twilight is ' attributed in part to the. netized ‘rods set in grooves ~

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PEE ge ETI, ms NET om Ae en ge Eee kee ee ae aa a este om It took Captain Knight two months to build this ‘observation post” without dis- turbing the young birds; in it he made many “close-ups” of the birds in action Taking a Close-Up of Young Birds in Their Nest | ITH all the secrecy and caution of wartime work at the front, Captain C. W. R. Knight built an observation post in a tree. He did not, how- ever, wish to observe an enemy in a near-by trench. His object was a peaceful one—to observe young hawks in their nest. In the dead of night he screwed a bracket to the tree and erected a moving-picture camera on it. He screened the camera with old sacking. Later he fastened a log to two branches and used it for a seat. It took him nearly two months to build his observa- tion post. The sacking completely covered the “post.” Captain Knight cut two small holes in the sacking, one for the camera lens and the other for him to look through. ; Often he remained in the tree for hours, observing the unsuspecting birds; whenever they made an interesting move he turned the crank. Popular Science Monthly - Oranges Are Now Used in Making Vinegar T has been demonstrated at the Citrus By-Products Laboratory at Los Angeles that oranges produce a fine quality of vinegar. Experiments were carried out in making the vinegar by two processes— the barrel process, for home use, and the generator process, for commercial purposes. They were equally success- ful. An interesting fact in connection with this new industry in those parts of the United States where the orange crop is important is that even frozen fruit can be used for making vinegar. Accurate Predictions from a Dutch Weather-Glass OR a few dollars you can buy an old Dutch weather-glass, consisting of a white glass vessel, sealed and air- tight except at the end of the spout. Pour clean rainwater through the > spout until it rises just above the top of the spout bulb, and let it stand fora day. The water should be of the same temperature as the air of the room in which it is to remain. The weather- glass must not be exposed to the:sun’s rays or to the heat of a fire, and it will not tolerate a draft. It must be hung exactly perpendicularly. With thése simple precautions the old’ Duteh weather-glass will prove 4% faithful weather prophet, for on the approach of bad weather the water rises in the spout, falling again as fine weather be- comes imminent. The instrument is said to be much more sensitive to weather conditions than a barometer. When water is poured through the spout, air of a cer- tain density and pressure is imprisoned in the upper part of the vessel. As we know, atmospheric pressure varies according to the weather, and it is this changing pressure, act- ing on the top of the water in the spout, that causes the water to rise and fall, the pressure within the glass remain- ing practically un- altered. In very bad weather the water may even overflow. The spout is graduated for reading. A sea captain says he has had an old Dutch weather-glass in con- stant use on board ship for forty years, and Said to be more sensitive to varying never found that their conditions than an ordinary barom- eter, this really scientific weather in- dicator can be purchased for a few dollars. Rain-water is all that is used in the weather-glass 46 ship’s rolling or pitch- ing disturbed the accu- racy of the weather- glass in the least.

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aE SS orm re OM Re Rai wr OW YY & \yv ‘ -may be_ increased August, 1921 Nothing Stops This. Gun — HIS caterpillar gun will ride over any incline that . does not exceed 45 degrees. The caterpillar chassis carries a 6.2-inch gun, the muzzle of which is.clamped down while the machine is in motion. This new type of gun was developed through the work of Mr. Walter Christie in cooperation with the United States Ordnance Department. It is a very mobile unit, self-propelled and able to take part in virtually any kind of an engagement. The power plant, which is a large gas- engine, is located directly underneath the muzzle and the controls of the gas-engine are within reach of the opera- tors. The big gun is here seen crawling over a steep hill somewhere in New Jersey, where it was given its first trial. One side of the embankment was 45 degrees and the other side was 35 degrees. The gun crawled over it with perfect ease. A traveling track, which is seen over the wheels, is used when the machine is crossing swampy country. Even in_ hilly country the new gun can reach a speed of twelve miles an hour. This to sixteen on a straight road. A Motion-Picture Cure for Faulty Acoustics N apparatus by which the action of sound waves and the phenomena of echoes and re- verberations in auditoriums can be reproduced in moving-pictures has been invented by Dr. F. R. Watson, professor of physics at the University of Illinois. By means of this invention:the acoustics of a proposed building can be tested out from the archi- tect’s plans, making it possi- ble to conquer echoes and other acoustic defects before, rather than after, the building is erected. A longitudinal section of the building under consideration, made from a narrow strip of metal, is set in a glass tank con- taining water of less depth than the metal strip. Intermittent puffs of air from an adjustable rubber tube are then directed upon the water in the model from a position corresponding to that of a speaker on a stage.- The waves thus set up are exactly comparable to waves of sound; they are reflected from walls and ceiling in exactly the same man- LAYER OF MOT CAME The new caterpillar gun of the United States Ord- nance Department, crawling over an embankment 10 Fitted up for four patients, this airplane has room for a pilot, a mechanic, a doctor, and a nurse a | - Ge Ambulance on Wings N England an airplane manufacturer has de- signed and constructed a hospital of the air. It is a big, powerful machine equipped with two 450-horsepower engines. These are able to drive it through the air at a speed of 110 miles an It carries a pilot, a mechanic, a. doctor, one nurse, and four patients. If the patients can remain in a sitting position, the cabin of the machine will accommodate ‘eight of them. Special supports are made for the stretchers, which slide in through a special door at the head of the machine. The stretchers rest in a tunnel that passes through the cabin. The biplane used has a span of 68:feet and a length of 43 feet.. It can carry a two-ton load and can climb 6500 feet in ten minutes with this load. hour. N= PICTURE A By taking moving-pictures of shadows reflected from water, building acoustics can be determined ~ ner as sound waves. These _.waves, so faint as to be invisible, are made to throw an enlarged shadow.on a plate of frosted glass above, which is distinct enough to be caught by a motion- picture camera that is placed vertically. .-.° | The streams of both light and air depend on a motor-driven de- vice placed beneath. A stream of air is periodically interrupted by being directed against a row of holes punched in a rotating iron disk. The air, passing through the holes thus intermittently, is con- veyed upward through a tube to the tank. Against a second row of holes in the same disk is directed light from a lantern. These spasmodic gleams of light are then reflected upward by a small mirror in such a way as to illuminate the model and throw an enlarged shadow of the water waves on the frosted glass plate, and it is the moving- pictures of these shadows that guide the acoustic expert. —

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penning eresemyetmne. A a oe Ai eehG PRR = + Here is a home- She’s cutting sweet po- tatoes into-+thin slices, so they will dry easily. The rotary slicer that she uses for the job will cut practically all kinds of vegetables. It can be ad- justed to cut uniform slices of any desired thick- ness; thus all the slices will become dry at the same time This cutter, which is used chiefly for reduc- ing cabbage to the form of sauerkraut, may also be used for slicing potatoes, car- rots, onions, pump- kins or squash so that they will dry quickly made drier that is very satisfactory. It is a packing-box fitted with trays made of galvanized netting. The top of the box acts as a door. The com- plete drier is mounted on a gal- vanized-iron sup- port. It is placed on top of the stove Drying Next Winter’s F ruits and Vegetables at Home In order to avoid any chance of fire the box may be completely covered with galvanized iron. The trays are filled with sliced fruits and vegetables, which are soon dried out by the heat of the stove. These slices can be stored away for months without rotting 48 Popular Science Monthly As she turns the handle, the potatoes inside the machine are hurled against a rough surface that tears off the skin. Most vegetables must be skinned before they are sliced and allowed to dry; for one of the chief functions of the skin is to prevent moisture from evaporating You place an apple against the curved sup- port at the center of the slicer and push the handle. The apple will be forced against the sharp blades and will come out in slices Whenever you wish to use fruits and vegetables that have been dried in this iron box, ail you have to do is to soak them in water. They regain nearly all of their natural smell and flavor in a very short time

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August, 1921 Some of the tricks which unscrupulous tradesmen play with weights and _ scales When Is a Pound Not a Pound? Photographs © Kadel & Herbert A can within a can gives the oil- dealer a chance to fool the pub- lic. The inspector of weights and measures uses his pliers when he is suspicious roe’ Here’s an old trick, but it is one that has netted peddlers many a dollar. A weight is tied to the scale arm —it is concealed by the box. Be suspicious when you see scales standing on a box In this ingenious arrangement, a cord is attached to the scale table and the opposite end of the cord is fixed to a small pedal. Pressure on the pedal makes the scales lie Here is a simple trick. An iron weight is attached to the bottom of the scale pan, and the unwary customer pays for a half pound of scrap metal that he never receives The unscrupulous iceman changes the position of the pivot on his ice-scales and in this manner robs his cus- tomers of seven pounds of ice every time he weighs a piece for sale

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Cars Geta ley vie a <a BRS LSE Tages Fn a Ta aa Sd nim, SF SSS aeons a=

Popular Science Monthly

Canceling 120 Letters a Minute PEED is the chief attribute of this mail- canceling machine. Its inventor spent fifteen years solving the problem of rapid mail cancellation. This machine is the result. It works like a typewriter. In- stead of twenty-seven letters a minute, which is the speed now, the machine can- cels as many as one hundred and twenty letters a minute. Mail is placed in a long feeder, in front of which sits the operator. A keyboard with fifteen keys is manipulated to direct the envelopes into fifty-six different mail- chutes, after the stamps on the letters are eanceled. A special machine is now being designed for use on mail-cars. Mr. Max Voighlander, the inventor, has interested the United States Postal De- partment in his device. Feet Are Needed to Propel This Boat PeODLE-WEEELS make the boat in the picture below resemble in miniature the old side-wheel steamers that formerly carried passengers and freight. As paddle-wheels are going out of style on the large boats, they seem to be coming in on small ones. What is more, the young man in the boat pedals the paddles. As he turns the pedals with his feet, the paddle- wheels on the sides of the skiff churn the water and easily drive the boat forward. The steering is done by means of a lever that operates a rudder. There is, however, a pair of oars on board that can be used should the foot mechanism get out of commission.

ESR oS

a | He Built a Wind-Shield for His Cigar-Lighter pore ordinary cigar-lighter is almost as easily blown out by a sudden gust of wind as a match. One tobacconist, whose stand was located outdoors on the munic- ipal pleasure pier at Ocean Park, Califor- nia, where the wind always blows, de- cided to remedy his customers’ discomfort when they tried to “light up” at his stand. After giving the matter considerable thought, he provided his cigar-lighter with the wind-shield shown in the picture. Now the customers’ troubles are ended, and they can light a cigar or pipe at the first attempt. Danger of Being a Prodigy ECORD of a remarkable mathematical prodigy appeared in the London Lancet some time ago. In this case the man’s extraordinary ability in arithmetical calculation was accompanied by an other- wise marked inferior general mentality. The prodigy was blind, yet he was able to calculate the square root of any number running into four figures in an average of four seconds, and the cube root of any num- ber running into six figures in six seconds.

© Keystone View Company This Machine Sews in Circles HEN the great lengths of cloth come from the looms in the mills, they must be sewn together before they are passed over the singeing machine and placed in the bleaching-vat. The machine that is shown in the illus- tration above, which sews in circles, is placed in the finishing department of the big textile mills. The needle travels around the circle and sews the ends of the long sheet together as it goes, thus producing a single long piece, such as are seen in the stores. This is then passed over a hot plate, which singes off the nap. The cloth is then ready for the big bleaching-vats. Many miles of cloth are handled every day in these mills. Good Roads Mean Prosperity for a Community ELOW is shown a one-man road main- tainer that is more economical than a horse scraper because of its greater speed and because, with its six-cylinder motor developing eight horsepower on the blade, it replaces two or three teams of horses and two or three men. Any one able to drive a car can operate this machine. The blade attachment is swung at an angle underneath the machine. The blade itself is adjustable both to the curvature of . the road and the depth of the cut. The outside right-hand blade is the smallest blade and it is placed in a more angular position. In operation it keeps the dirt always rolling toward the center.

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August, 1921 Hold the Transmitter to Your Throat in Telephoning bones a telephone is located in a noisy place, much of the noise is transmitted when anybody talks over the telephone. This makes receiving difficult at the opposite end of the line. To eliminate this trouble a “throat trans- mitter’’ has been developed. The trans- mitter is placed against the throat, and the voice is transmitted just as clearly in this way as in speaking into the transmitter and the noise is eliminated. Such transmitters were much used during the war. Even an ordinary telephone will transmit sounds when held to the throat. © Keystone View. Company When the Elephant Gets a Cold ——" catch cold just as other animals do, and when this is the case the keepers at the zoo have a hard time curing them. Above is pictured one of the methods used. A bucket containing boiling hot vinegar is placed in a canvas bag. The bag is then placed over the big fellow’s trunk, so that he will inhale the vinegar vapor. Fresh Air by Megaphone b sca air may find its way into a closed =. ~ room through a megaphone. This megaphone is connected with a long pipe that leads to the roof of the house. The pipe has a covering over it to keep out the rain and snow. : ’ A cool stream of air flows down into the face of the sleeper. In some cases it is better than having a window open. Any An elephant seldom objects to this old phonographic megaphone may be treatment, since he seems to understand pressed into service, and it makes a very that it helps him to breathe. The picture Detecting Bubbles in Castings good use for an old article that is not of shows him taking his medicine like a man. much value otherwise. N the manufacture of a small automobile accessory Harold G. Fitzgerald, of Los Build a House for Twenty Cents Angeles, California, uses a small casting of Tripods Support Fire-Hose aluminum alloy. Such castings sometimes "Twenty cents will buy you an ice- contain bubbles, and a bubble means a F course, street-cars and traffic gener- cream soda, and it will buy you a house _ hollow place and therefore a weak spot. ally must be stopped in the imme- —that is, if you can follow the methods Considerable trouble was experienced diate vicinity of a fire. But often there used by Mr. Lewis Dart, of Redondo with these castings. Breakage was usually are hose leads carried for blocks, across Beach, California. due toa bubble. Mr. Fitzgerald conceived streets, and effectively tying up traffic not Mr. Dart arrived in California a sick the idea of testing the castings by weight. otherwise affected by a fire. man without funds. He gathered the A solid casting would weigh a certain Years ago, in Washington, firemen used wood that drifted on to the beach. He amount, and obviously one with a bubble a couple of tripodlike affairs that they drew out the nails, straightened them, and in it would be lighter. An apothecary’s placed on each side of the street-car tracks. began to build his house against the rocks. small balance was used for testing. These tripods served as supports or abut- As the wood drifted in, the house grew in ments for the hose that was carried over size, until it was ready for a roof. them as a sort of suspension bridge, under It was then that Mr. Dart discovered which cars and other traffic could pass. that he did not have enough nails to finish This apparatus might well be adopted by the job. He bought twenty cents’ worth. other city fire-departments. Its use would Now he is a strong, healthy man, and he avoid the blocking of traffic at fires of any earns his living by serving lunch on his magnitude which often disrupts an entire veranda. street-car system for hours.

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Popular Science Monthly

When a Burglar Says ‘‘Hands Up” N EETING the owner of the cash or diamonds he is looking for, the high- wayman directs his victim to raise his hands. How can that unfortunate obey and at the same time reach for his gun? This is the problem to which Samuel Vlanch, of Sioux City, Iowa, applied him- self, with the result that he has invented a belt to which to attach the revolver, carry- ing a mechanism connected with a hinged strap that passes over one shoulder. When the arm is suddenly elevated, this mechan- ism operates in such a manner as to pull the trigger of the revolver. Query: Would it be safe for a lady to say “‘good evening’”’ to the wearer of this belt? Keep a Stove in Your Pocket Am alcohol stove that you can keep in your vest-pocket! It is not a mere freak, but a practical little device that will produce considerable heat for the warming of beverages or the heating of curling- irons. The alcohol burns through a small piece of fine copper gauze—no wick is used. A small cover.fits over the top and pre- vents the fuel from running out into the pocket. The device is no larger than a watch, and it may be carried about in 4 man’s pocket br a woman’s handbag with the same _ con- venience. A small charge of alcohol will bring a fair-sized pot of water to the boiling-point in a short time. Several charges of fuel will cook a meal.

Steel Rope Holds Back Crowd N order to keep the crowds on the side- walk during parades in San Francisco, the police department has adopted the plan of stretching a steel cable along the street near the curb. It is supported by heavy wooden posts placed at regular intervals. The cable is wound on drums and when not in use is stored away. Just before a parade starts, special wagons distribute these drums at appointed places along the street, and a crew of men erect the wooden posts and attach the steel cables to them. Later these same wagons follow up the parade, and the posts and steel cable are loaded into them.

He Has Six Fingers on Each of His Hands 6) jptaescga setae seeped you hear of a man who has too many fingers or toes. Did you ever see one? If not, you will be interested’in the picture of the man shown above. He has six perfectly formed fin- gers on each hand, and they all are active members. When the - photographer wished to take his picture, he obligingly rested all twelve fingers on his chest. The only time his extra fingers bother him is when he wishes to play the piano—they get in the way. According to biologists, if this twelve-fingered man should marry a twelve-fingered woman, most of their children would have twelve fingers, ~ though the tendency might not ap- pear until the next generation. 52

Acetylene Headlights for Hunters ILD animals nowadays have an un- happy time attempting to escape the hunter. The modern hunter wears an acetylene lamp fastened to his cap and sup- plied by a generator carried on a belt around his waist. Such a lamp leaves the hunter’s hands free and throws the light where he is looking. The light is so penetrating in its bril- liance that it shows objects through the thickest fog or mist. It cannot blow out and has a self-lighting attachment that makes matches unnecessary. It is claimed that this lamp will burn ten hours on one charge of carbide and water, and costs less than one cent an hour. This Strop Also Fits the Pocket "T BAVELING men will surely welcome a razor-strop for safety-razor blades that is small enough to be carried in the pocket. This makes extra blades unneces- sary. Provided the strop is in his pocket, a man going away from home for several days need take merely the blade in his razor. Two specially prepared rubber pads are . mounted in a little holder so that they may be pinched together. The dull razor- blade is also provided with a small holder so that there will be no danger of a cut’ finger when’sharpening a blade.

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at ne les he August, 192] Units of Electrical Resistance HE ohm is the unit of electrical resist- ance. Electricity meets resistance in flowing through a wire just as water meets resistance in flowing through an iron pipe. Often an electrical worker must crowd a great amount of electrical resistance into a small space. We might say that this resistance is used to hold the electric current back and to prevent too much from flowing through the circuit. The little device shown above has an electrical re- sistance equal to many miles of large copper wire. One million ohms are crowded into a very small space. When an electrical current meets such an obstacle as this, it must struggle to get through, and much of it is prevented from doing so. Such resist- ance units find wide use in electrical experimental labo- ratories. His Store Floats and Customers Arrive by Boat “ieee row over to the store,” says the man who wants to buy some marine supplies. The owner of the store pictured below figured that marine supplies could logically be sold from a boat, and he was not mis- taken. He started with a single store. Business was so good that now he has de- cided to build a chain (or a fleet?) of store- boats. He will place the boat-stores near busy waterways and harbors, where motor-boat owners, rowboat owners, canoe owners, even yacht owners, are sure to be found, with all their varying needs of special marine equipment. The windows give some idea of the varied stock required. Sermons by Wireless HEN the pastor of a church in Pitts- burg was suddenly taken ill on a Sunday afternoon, when it was impossible to obtain a substitute, a novel plan was resorted to. The Calvary Episcopal church, located ten miles away-in the same city, had been sending out its service by radio for several months. The pastorless church installed a compact receiving-set and a loud-speaking horn, and the music and the sermon in the Calvary Church were distinctly heard. There is one advantage in the preacher’s being ten miles away: he could not see that bald-headed man in the third row who always sleeps comfortably throughout the discourse. It Bundles Grain into Shocks = rapidly bundling grain into shocks so that it will not be exposed to rain, Harry Baxter, of Newman, Illinois, has invented a revolving device attached to a harvester. An operator takes the sheaves as they are deposited from the binder, arranging them compactly in a hollow frustrum. When it is desired to top the sheaf with a cap, the first sheaf inserted in the frustrum is spread at its base and the other sheaves are inserted against the spread one. When the hollow frustrum is full, the support is swung out of the path of the shock by manipulating a handle; thereupon the loaded frustrum will drop, the shock turn- ing to a vertical position. Rubber Coats for Watches parses your watch from scratches, dirt, falls, and general hard wear by enclosing it in a rubber case during working hours. This idea comes from Mr. J. E. Me- Kenzie, a resident of Medicine Hat, in Canada. The picture above shows one of these cases in use. The back of the cover is made entirely of rubber and the front half is cut out to expose the face of the watch, an idea evidently taken from models of old hunting watch- cases, which sometimes had practically the whole face covered and the figures of the hours engraved on the case. There is a hole at the top for the stem. Thus the rub- ber case can be put on and taken off rapidly at the be- ginning and end of a working day. How They Learn to Swim in Scotland - every swimming instructor has a method all his own. In the pic- ture below you see a Scotchman teaching a girl how to swim in a small pool located within the entrance to the Firth of Forth. The instructor stands on a platform, with a rope in one hand and a pole in the other. His victim is held in the water by means of a swing that is suspended from a pulley and controlled by the rope. What is the pole for? To correct the swimmer’s arm and foot movements, and the pulley permits of a quick adjustment of the swimmer’s body in the water. Imagination is left free to picture what would happen should the instruct or lose hold of the rope. MARINE & GENERAL SUPPLIES - PAINTS a

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ane CE PRR P cts a SUGGthc aap ERE: teneee aeeereen Ae pete ek eis | Shier ieee enn nil eae erent rae a ee ee ae eee aE Spe a ic ON ae lee sete eee ea ei ee eee 1 be wie Ne IS te = ra Ricoeas Popular Science Monthly This Little Implement Makes Knife-Sharpening Easy *”NIFE-SHARPENING with a steel or a grinding-wheel usually requires a certain amount of skill. You must know the proper angle at which to hold the blade and the pressure necessary in order to give a smooth finish. There is now a knife-sharpener that attends to these details for you. j It consists of two rough-edged wheels mounted on a wooden handle so that they touch each other. To sharpen a dull knife you draw SWATER 2. BOILER = EXPANSION TANK OR ® B. ICE-WATER TANK — DF “UT-OUT JALVES it between the two wheels and it is No Excuse for Letting the Tooth-Paste Dry | ow often do you put the screw- cap back on your tube of tooth- paste when you finish using it in the morning? Most people have a habit of leaving it off. The paste at the mouth of the tube dries during the day, and the next morning it is hard and useless. For the busy, nervous man who simply cannot remember to replace the screw-cap, the little hinged cap shown in the picture above is recom- mended. It opens like the cellar door. Most important, it is never sharpened on both sides simultane- ously. The wheels can be revolved into a new position when they become dulled from too much wear. Salt Water Kills Grass ear helps to preserve cut vegetables, and yet when it is sprinkled on the ground it will kill any vegetation. If you wish to make a path across your lawn, for instance, sprinkle salt on the grass instead of digging it up. The salted grass dies. In the picture below you see two men literally salting down a path. One of them pumps the salty water while the other one holds a hose over the doomed grass. It is possible that students of agriculture have taken note of the effect of salt and alkali on the vegetation of Colorado and Arizona, and other Western states, and that they learned they could apply nature’s methods to their own ends. Common salt and green vitriol (iron sulphate) or blue vitriol (copper sulphate) are commonly used to eradicate grass. Turn the Heating Plant into a Cooling System ANY men, moved by the unsightli- ness and utter uselessness of radiators in summer, have wondered why they could not be used to cool a hot room in July or August. The same pipes that conveyed hot water or steam throughout the house in the winter will also carry cold water in the summer and keep the air of the house from eight to ten degrees cooler than the outdoor thermometer registers. This result can be accomplished with very little expense once the hot-water sys- tem has been installed. Of course you will need a water-cooler for the summer. It may be installed in either the cellar or the attic, unless there is a well in your grounds from which you can get naturally cooled water. Pans must be placed under radia- tors to catch the moisture. Also there must be outlets at the top of the radia- tors, as cold naturally has a reverse action to heat. lost, since it is always fastened to the tube. Thus there is no possibility of the tooth-paste getting dry and useless, and in consequence being wasted. The Spout Swings to the Tree A FEW years hence the city of Glendale, California, plans to have one of the most beautiful oak-tree drives in the coun- try. All trees along a five-mile motor thoroughfare have been removed and tiny live-oaks have been planted at regular in- tervals along the road. Until these little oak-trees are well rooted, they must be carefully tended. The watering of them presented a problem, be- cause there are no water-mains for three miles along the oak-tree avenue. The city engineer rigged up a tank- wagon. This wagon has a spout that may be swung into the parkway along the road to water each tree. The driver merely swings out the spout and turns on the water. He proceeds from tree to tree until the whole lane is watered. :

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August, 1921 © Keystone View Company The Traveling Lawn-Mower and His Outfit Is This an Automobile or a Motorcycle? owe ANGELES boasts a man who believes in doing a job enti hajenagat above is a peculiar combination of motorcycle and thoroughly, even the apparently simple job of looking after lawns and shrubbery. This man makes a business of cutting grass and taking care of lawns. He is a great help to the busy suburban dweller who likes to see the grass cropped closely but does not have the time to do it himself. Along comes this man with his “shop,” and within a few hours’ time he has trimmed the grass and shrubbery. to the queen’s taste. He uses a bicycle with a small rubber-tired trailer to carry his tools. The bicycle is clamped between two rails that are attached to the front of the trailer. With a Hatpin She Makes Rye-Bread Flowers PrROM loaves of rye bread flowers grow—that is, if the bread is in the hands of Mrs. Johannemann, of Willowemoc, New York. She takes a fresh loaf of rye bread in one hand and a hatpin in the other. In a short time the top of the loaf is trans- formed; roses, violets, tulips, and leaves are the result of her skilful manipulation of the pin. It is not unusual to see flowers made of vegetables, but that does not appear such a difficult art as making them of bread, which has such a tendency to crumble. The picture above shows a box of rye-bread flowers that Mrs. Johanne- mann made and sent to Mrs. Harding at the White House. The bread dries soon and as a result the flowers become firm. cycle-car. It drives like an automobile and rides like a motor- cycle. In place of the usual handle-bars, the machine has a wheel Photographing the Last Lap HEN the finish of a race is close, it is often difficult to determine which horse first crossed the line. The judges have an unob- structed view of the track and are in a better position to judge the result than persons on the ground level. But in the excitement of a close finish the observers are sometimes misled, and disputes arise concerning the judges’ decision. The camera shown below makes such disputes impossible. At the moment of the finish the shutter is released and an indisputable record is obtained. similar to those used on automobiles. When the vehicle is standing still, two small rubber-tired wheels are placed in contact with the ground to prevent the machine from overturn- ing. These wheels are manipulated with handles. The wheels are also used when the machire is traveling at low speed in heavy traffic. The trailer wheels are fitted to the chassis in such a way that they will follow the uneven surface of the road. A low center of gravity prevents slipping and skidding. Make Your Own Candler for Testing Eggs POULTRY husbandman of the United States Department of Agriculture has devised a simple egg-tester that can be made at home. A tin chimney with an extension on its side is used in connection with an oil-lamp. The extension is provided with an opening and the egg is placed in front of this. A dark room facilitates the identification of a bad egg. The big end of the egg is held up, a position that readily re- veals the size of the air cell as well as the condition of the embryo. An in- fertile specimen, incapable of ger- mination, looks clear when candled, yf while a fertile egg betrays a dark spot described as the embryo. When the embryo is diseased and the egg has been incubated for at least forty- eight hours, the blood. settles away from the embryo toward the outside.

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a en ee Popular Science Monthly More Water for the Propeller An ingenious device that lifts the water in shallow streams HEREVER shallow water is encountered in canals and little rivers, there is danger of boat propellers fouling the. bottom. To prevent this the propellers are some- times housed in vertical recesses in the hull, known as “tunnels,” the tops of which slope downward fore and aft. For vessels that are of considerable ‘draft, even when light, this arrange- ment serves the purpose; but when the draft is very small, the tunnels are of little use, as the propellers must necessarily be submerged a certain depth, which may be greater than the draft of the boats. How Additional Water Is Raised An Englishman named McReynold has invented an ingenious device by means of which, instead of being obliged to lower the propeller of a shallow-draft boat below the level of the keel, water is actually raised by suction in the propeller tunnel to a By P. J. Risdon English correspondent for the Popular Science Monthly higher level than the surrounding water, and maintained at that level as long as the propeller is at work. It sounds rather like holding on to some- thing and trying to push it away at the same time, and in point of fact the analogy is not really a bad one because it appears that efficiency is to some extent impaired. The device is simplicity itself. At the top of the tunnel is a tube, or pipe, connected to an air-exhaust pump. When the pump is started, it exhausts the air from the tunnel, and the re- sulting suction draws the water in the tunnel up to the required level, com- pletely submerging the propeller, the lowest point of which is thus kept well above the lowest point of any shallow- draft, flat-bottomed boat, and conse- quently protecting the propeller from damage. Outside the tunnel is fitted a glass tube in which the water rises to the same level as in the tunnel, and which thus serves as a water-level indicator or gage. The propellers, of which there may be either one or two, are inclined’ slightly downward at an angle of about: ten degrees with the horizontal. Some of the Results It is further claimed for the system that it eliminates “‘wash” from the propeller, and renders it highly satis- factory on canals and narrow water- ways. In a recent trial on an English canal, a boat, fitted with a thirty-four- horsepower, four-cylinder motor, and loaded with twenty-five tons, was pro- pelled at a speed of four miles an hour, and afterward, acting as a tug, towed another barge laden with thirty tons at a speed of three miles an hour. This does not denote a high degree of efficiency, but efficiency has sometimes to be sacrificed in order to meet unusual circumstances. © Modern Publishing Company THE MCREYNOLD SYSTEM OF PROPULSIONg S FITTED TO ANZENGLISH CANAL BARGE — * Vacuum ® PR ump - fi Drawing by G. H. Davis In thig invention of Mr. McReynold’s, water is raised by suction in the propeller turinel to a Iével higher reper than that of the surrounding water, giving the propeller sufficient water, in shallow streams, to work in 66

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August, 1921 Enameling with a Torch N the ordinary process of enameling, sheet iron is first freed from grease in an oven, cleansed and dried, then covered with a layer of enamel. This first layer is then melted in an oven, and an enamel of different composition applied, melted, and cooled slowly. Now a new process has been evolved that is incomparably simpler. An enamel powder is drawn in small quantities from a reservoir. It is drawn off in a current of driving gas of compressed air or oxy- gen. This driving gas current mixed with enamel powder is intro- duced into the nozzle of a burner, the nozzle system of which is fed with an explosive mixture of combustible gas with oxygen or compressed.air. The enamel. powder, blown forward at a high speed by the jet of driv- ing gas, is melted in the hot flame produced by the igni- tion of the explosive gas mixture, and is projected on the work to be enameled with great force. The latter should’ be heated to a_ temperature sufficing for the welding of the liquid enamel, which is either effected by special agents or by another flame coming from the nozzle sys- tem. A uniform adhering coating of enamel,’ the thick- ness of which depends on the duration of the sprinkling process, is produced by this means. By slowly moving forward the enamel sprinkler, the whole surface is evenly coated. This process is cheaper than the old way; also the . enamel is more durable and In a new process for enameling, 4 : a powder is drawn from a small permits of defective parts reservoir in a driving gas of being readily repaired. compressed air or oxygen ‘at 7 ¥ ona aed Co ed iad it #*) Peak * a He is making a map of the stars by the simple method of marking them on a glass plate You Can Make Your Own Map of the Stars NY amateur astronomer can easily make an accurate map of the constellations. He has but to lie on his back and mark, or “spot’”’ on a sheet of transparent material, such as glass, the stars overhead just as he sees them. The brighter stars can thus quickly and readily be located on the glass, after which photographic prints can be made by using the glass as a negative. In this manner it is possible to plot all the bright stars passing across the zenith and a large surrounding area of the sky. Reference to a star atlas, or star chart, will disclose the name of each star. The best way to become familiar with the stars is to observe them on a few clear evenings during each of the four seasons. Thus the conspicuous stars of spring, summer, autumn, and winter can be learned. When you have thus made their acquaintance, they are easily remembered. Health Determined by the Amount of Oxygen Consumed FT HE amount of oxygen consumed in performing a particular piece of work is believed to be a definite indi- cation of a person’s health and general physical condition. To diagnose your health it is therefore as important to measure your oxygen supply as to take your pulse or temperature. An ingenious instrument has been devised that will measure the intake of oxygen as you write a letter, saw a board, walk about the room, or per- form other familiar forms of exercise. It is in use in the laboratories of sev- eral colleges and in the near future will probably be part of the equipment of doctors’ offices. In order to measure all the air in- haled, the instrument is fitted with a mouthpiece like those used on gas- masks during the war. A piece of rub- ber fits under the lips in such a way that no air can be inhaled or exhaled except as it passes through it. The nose is closed. meanwhile by strong sible for the patient to move freely about the room and perform a variety of exercise. An observer meanwhile obtains accurate readings of the quan- tity of oxygen consumed. When a case is to be diagnosed, the patient is first examined while lying upon a couch, so that the consumption of oxygen during relaxation may be compared with that going on while the patient is performing various tasks. Readings are then taken while the patient operates a typewriter or moves about the room or performs some more violent exercise. When these readings are taken in connection with the blood pressure, temperature, pulse, and other symptoms, an accurate diagnosis be- comes possible. The results of a series of experiments made in various labota- tories have proved of great value. By examining a variety of subjects under various conditions it has been possible to establish the normal —_ * ° Kadel & Herbert nippers. From the mouthpiece runs a en amounts of oxygen required for various forms of work. When a patient’s oxy- lon : ‘ In measuring the amount of oxygen s : : g, flexible hose connected with the = ened ilee dacbinatty: teenie: clnenned gen consumption is measured, his Ouygen‘tamk.: °° -:r > - “and ‘a mouthpiece is placed over variation above or below:the normal The length of the hose makes it pos- the mouth can be given at a glance. 57

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Popular Science Monthly | In the City of the Lilliputians Seventy small people have their Yes, there is a fire de- ° ° partment, and it greatly own fire department and police interests ‘visitors. We A . : doubt, however, that it force in their own little town weet Get comnts mA LF a eS ee a ee ET EOE er ae, $9 te er RRR ere emerge Sosinare ae ao es ae ent cer em) IO TE ee —— = ee a aeeeneraseeememeeeeten toes STS s sok are pence et ee SE err] te es ve ta ~ Pe \ ie 3 These men and women—some of them no larger than dolls— are perfectly normal in all other respects. They live in a small “Bel eo town where all things are small, not very far from Berlin par a Bi Po ae a fh ovals ‘e View Company the Lilliputians Here you see the oldest inhabitants of the town; both of them are sixty-eight years old. They own a small toy-shop and earn their living selling toys to curious visitors This is the candy-store, and it is well patronized by the children of the neigh- borhood. The counter, which is the right Photographs © Keystone height for children, is almost too high for The post-office is the center of interest, as is the case A man in a bartender’s coat is brought up before a in all small towns. Most of the relatives of these police captain. If he lived in the United States we people are-full grown should know why he was brought there 58

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August, 1921 Solving a Few of the Knotty Problems that Face the Photographer An old clothes-wringer will jebeewth, greatly reduce the time usu- Bizea? eT ally consumed in ferrotyping. The photographs are placed on black ferrotype tins and A plate is not necessary in taking photographs of lace. rolled through the wringer ~ ae seth Instead, the lace is placed on sensitized printing paper, exposed for a second to daylight, and then put in the developing solution (Left) The problem of keeping the dark-room dark in order not to disturb negatives in the developer has troubled many pho- tographers. Opening and closing the dark- room door is the chief cause of trouble. Here’s the remedy: Make a revolving door out .of four regular doors (Right) He’s taking pictures of the ceiling. On his chest stands one of the new aluminum lamps, weighing less than two pounds. Ly- ing on the floor in this fashion, he_is able to manipulate both lamp and camera with ease This touching message was written in pencil on sensitized photographic paper in the dark-room. It was exposed to the light for a second and then washed in a tray of ordi- nary water to| remove the pencil marks. The writ- ing was invisible and did not show up until the paper was put in a de- veloper solution

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REI * AE DA PL <M A ta AP Rite AN IY ee A x nn ea ECT Rg Lt ei RE Ae wi ’ ae ~ 2S ee ee Eas ce eer oe Dae

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a cogepacte gerne os ee eee Popular Science Monthly

The Truck that Hugs the Barrel HIS paper- and _barrel- handling truck has a bear hug. Its steel arms hug so tightly that they are able to lift a heavy roll of paper clear off the ground and carry it away. The grip of the arms is tightened about the paper by an electric motor that is sup- plied with current by the storage-batteries carried by the truck. This same motor drives the truck seven miles an hour. The arms will grip a roll having a diameter of three feet.

Easier Work for the Glue-Makers [* the stockyards are great : piles of refuse ready to be hauled to the glue works. Formerly two workmen, one who pulled and the other who pushed, constituted the pro- pelling machinery of the hand- cart into which the refuse was shoveled. With the aid of a small tractor, one workman now pulls three or more of the cars loaded with the scraps of animal substance from which the glue is to be made. Allhe . has to do is to operate the lever-controls of the tractor, running his train of cars up to the pile. With every train of three cars, one man does the work

To Strop Safety-Razor Blades ANY men who shave themselves now prefer to do it with the little safety razor. The only disadvantage attaching to this has been the necessity of keeping on hand a supply of new blades; for, unlike the old-style razor of our grandfathers’ day, it was not possible to sharpen the blade. Now, however, there is an inven- tion that makes it easy to strop safety- razor blades. The apparatus is made.of wood and con- sists of two parts arranged scissors fashion one above the other. One of these carries two pins that accommodate the razor- blade, while the other has two slots that allow the device to be closed. In addition to the use originally planned, its ingenious inventor discovered that by keeping the blade in the apparatus the razor could be used in the manner of the old-style razor.

Lecturing to an Audience of Deaf People ECTURING to deaf people. That sounds peculiar, but it has been made possible, and it is now an every-day occurrence in Germany, where the system was developed. Each member of the audience is provided with a small ear telephone connected with an electric circuit that also contains a powerful voice- amplifying device that is placed before the speaker. The members of the audience receive the amplified voice currents through the small ear telephone, and all other disturbances are eliminated. This system has been introduced in America, and a very successful lec- ture was carried some time ago in New York city. There is nothing complicated about it and nothing to get out of order. ‘‘Shines’’ Flow from This Brush HOE-BLACKING and ink are not un- like in many respects; hence it is not surprising that a fountain-brush for shoe- blacking has been invented. The blacking is contained in a metal tube to which a small brush with a hollow handle is attached. At the point where the tube and handle meet is a push-button that controls the flow of the blacking into the brush. The picture below shows the fountain- brush in action. As the user presses the button with his thumb, the blacking is released. The tube is air-tight; hence the blacking within cannot evaporate. of six.

It Floats and Is Sanitary te day James W. Carrico saw his young son thrusting his arm into a pail of drinking-water and fishing for the cup. The boy was wet up to the shoulder, and undoubtedly the water was the richer by a few thousand germs. It was right there that the idea of the unsinkable cup was born. Outwardly Carrico’s cup looks like any ordinary tin cup. But it has an airtight compartment on the handle side that occupies about one fifth of the cup’s diameter. It is this airtight compartment that keeps the cup afloat, and the compart- ment having been placed on the handle side of the cup, naturally it is that side that stays uppermost in the water. The principle is the same as that em- ployed in shipbuilding, where airtight bulkheads are used to prevent a ship from sinking.

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£4 OO @O «+ & CF is ne T, er he ny ht at ’s nt rt- lle de m- tht 2m August, 1921 © Keystone View Company Traffic Cops in San Francisco Merely Push a Button _ FRANCISCO has its own peculiar traffic problems. Here is a device that has been invented to help the San Francisco traffic ‘“‘cop.” It is motor-driven, and when the traffic policeman wants the traffic to stop or pass in either direction, all he has to do is to push a button When he pushes this button, the motor turns the sign and at the same time blows a whistle. When the machine is in use, it is sus- pended over the center of the street by two small cables. In the picture above it is shown being cleaned and made ready for the day’s work. He Wears His Chair Te chair jacket pictured below is the invention of Jeremiah Holliday, of Winnsboro, South Carolina. It is intended for workers who must move from place to place and carry their chairs or stools with them. A circular chair seat with support- ing legs attached to it is fastened halfway round to a canvas jacket. The front of the seat has two deep grooves in it to make room for the wearer’s legs when he stands up. Corresponding cuts are made in the jacket to enable him to sit down with ease. The jacket opens up the front, and the wearer gets into it just as he would get into an ordinary coat. After he has buttoned it, he fastens the ends to a projection on the chair. The chair needs no adjusting and will fall in line when the wearer changes his position. _ butter to a molten condition. Hungry Caterpillars Make Up - This Moving Circle once opirie gtoimanes caterpillars will go round and round in a circle until they drop exhausted, because they haven’t much sense. These caterpillars usually travel in a procession, one of them becom- ing the leader and the others following blindly. As they travel they spin a fine silk ribbon that guides them when they wish to return home. Any caterpillar may become a leader. But suppose the begin- ning and the end of the procession meet, thus forming a circle—what happens? The leader is lost and the caterpillars travel blindly in a circle, following the silken thread—sometimes for days. Henri Fabre, in his book “Life of the Caterpillar,” tells of an eight-day proces- sion around the edge of a vase. After the caterpillars had climbed to the rim he removed the silken thread which they had spun on their way up the side of the vase. In regard to this Fabre says, ‘“The cater- pillars in distress, starved, shelterless, chilled with cold at night, cling obstinately to the silk ribbon, covered hundreds of times, because they lack the rudimentary glimmers of reason which would advise them to abandon it.” Why You Should Not Melt Butter | ed elae suffers considerably when it is allowed to melt in the air. This dis- covery has been made by an Englishman: The important vitamine in butter, which scientists call the ‘‘fat-soluble A,”’ is completely destroyed, even at the low temperature necessary to bring the The same vitamine that is in butter is also present in milk, and this brings up the question of the advisability - of heating milk in the Pasteurization process. 61 How the Fruit Train Can Be Cooled EFRIGERATION of freight-cars is of great importance from an ice-conser- vation and expense standpoint.- Unless the cars of fruit are properly cooled before starting on their transcontinental trip, it is necessary to replenish the ice-bunkers three or four times in transit. The reason for this is that fruit is warm when loaded into the car and much of the ice is consumed in lowering its temperature. Where the cars are pre-cooled, this diffi- culty does not develop. Special cold-blast pipes, which are ad- justable over the hatches of the _ ice- bunkers, are used in pre-cooling the cars and their cargoes, the cold air emanating from ammonia plants in special refrigeration systems located at terminals. Wheeling the Baby Electrically HEELING a baby-carriage uphill is tiresome work; hence we now have the electrically driven carriage. It was in- vented by a Scottish clergyman named Mackenzie. The battery-box that sup- plies the power is located under the body of the carriage, and a series of chains and sprockets sets the carriage into motion. It travels slowly forward and is guided by the nurse at the handle. When she wishes to start or stop the carriage, she pulls a switch-lever. A rope leading from the handle to the rear end of the carriage is a sort of friction brake, enabling the driver to reduce the speed of the carriage without stopping it.

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Dy gen 2S RRA Deere Les ee OE oe ae en eee Sa ame PORE PN, VRRRITES ih oe oS, —— ERR tee eek = Se age altar ed = oy Sian oe SS SSS Per ss tk, Bh aS EN. a pair of trousers. these six necessary? An English tailor thought the matter over and decided that three would do the work just as well. upon he constructed the trousers shewn above. waistline there is a pointed piece Three-Point Suspension for Trousers SUALLY there are six buttons for suspenders on the edge of But are all Where- Instead of the usual straight of material attached at the back. One button appears on the point. In the front the same sort of thing happens on each side. Thus the three buttons do the work that six did before. Se Balanced Rations for Chicks On upon a time, two tiny chicks broke through their shells at the same moment and fell into the hands of the Department of Agriculture. One chick was fed properly—his rations being care- fully balanced. The other chick was fed the way the average farmer feeds his chicks —that is, in a haphazard fashion. What happened? At the end of five weeks the chick fed on a balanced diet weighed nearly nine ounces, and the other one weighed but five. Chickens and people differ very little when it comes to physical growth, and the experiment of the Department of Agricul- ture described above for the benefit of the chicken-breeder could be applied with ad- vantage to human beings. Take Your Own Camp Grate RB UILD a fire in the woods and cook your dinner on it—that sounds very tempt- ing; but unless you carry some sort of grate with you it will be a difficult under- taking. The camp grate shown below is made of metal and is mounted on four legs that sink into the ground. One end of the grate is for pots and pans; the other end is used for frying. There are metal side curtains to prevent the wind from spreading the fire and to concentrate the heat under the food. We Now Have the Notched Hammer Handle | Dae a hammer ever fly out of your hand? If you take a heavy stroke and you have a light grip, the hammer is apt to fly from your hand with considerable force. And if any one is standing in the way of it —well, some one will be hurt. You can use this hammer with no danger of its leaving your hands. Notches are cut in the handle to accommodate your fingers. It is not necessary to grip the hammer handle so tightly. The notches, therefore, considerably reduce the fatigue of the arm muscles. You can actually do more work with this hammer than you could with the ordi- nary hammer that for so many years has held its place in the toolbox. Popular Science Monthly Specially Made Shoes to Wear on the Beach iy! the picture is a little maid digging for shellfish that hide themselves in the sand. She is wearing beach shoes that are rem- iniscent of the clogs and pattens of the old world, although the princi- ple of a wider surface to give greater security on soft ground is certainly taken from the skis of Norway. These shoes are worn by beach workers on the west coast of Eng- land where there are quicksands. People who live near such places literally have to watch their step, and the centipede shoes make it easier to do so. This Fan Fits Any Socket HERE is now a small electric fan that will screw into any electric-light socket. It is threaded at the end like an electric bulb, and can be moved from place to place as easily. The fan blades have a metal guard around them to protect the fingers from possible injury. / The picture below shows the fan attached to an ordinary desk-lamp fixture. It can be twisted to any desired angle, since it is flexibly connected with the threaded end. If desired, the fan may be operated at the same time as the light is being used, simply by providing a double bulb socket. ao GEL

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nce led at ket. August, 1921 Special Memorandum Pads for the Blind HAPED like a waffle-iron is the new aluminum memorandum pad for blind people. A piece of paper is placed between the corrugated sections before they are brought together. The pad is then ready for use. When the blind man wishes to make a note of something, he takes a small metal punch in one hand, the pad in the other, and punches holes in it, guided by perforations in the upper corrugated section. Thus the paper is pierced, and small raised points appear on its under side. _The blind man punches the holes in accordance with the alphabet for the blind. When-he runs his fingers over the raised points, he reads off what he has written. The blind have many friends. Witness the number of inventions continually being brought out for their benefit. The Fireless Cooker Field Oven HE fireless cooker, which has made its appearance in many homes, is now being built on a larger scale in Russia. Professor Rotatiyow has constructed a field oven for use in Russia’s many wars. It is built on the fireless-cooker principle. The oven proper is surrounded with in- sulating material that prevents the heat from escaping. Hence, after the oven has reached the proper temperature fuel is not needed for several hours. This fireless oven not only saves fuel, but it also saves considerable coal-shoveling, and any cook of any household will testify as to the immense amount of watchful care saved. a MR Sa... eS: ae _ (FAL ‘J Fil, — Airships Are Now Moored to Mastlike Structures N° so long ago the idea of building mooring-masts for airships was con- sidered fantastic. And yet they are actu- ally in use to-day in Pulham, England. Great difficulty has always been encoun- tered in handling dirigibles on the ground; frequently they have been dashed to pieces by strong winds. Their immense size as well as ground gusts have made the moor- ing problem a hard one. Mooring-masts enable airships to swing in the breeze like a weather-vane. Air- ships have been tethered to mooring-masts for periods of six weeks in all kinds of weather. The picture above shows the actual point of contact of the dirigible R33 with the new mast at the Pulham airship station. The crew boards the dirigible by a ladder. By Their Beads Ye Shall Know Them OST of us have read of babies who were changed in the cradle and of the confusion arising therefrom; the-.subject has long been a fruitful one for story-writers. A certain maternity hos- pital in New York city is doing its best to avoid such accidents by a very simple scheme. Lettered beads are strung into a necklace for every new baby, spelling its name, so that there is no possible chance for its iden- tity to be mistaken. To make assurance doubly sure, the ends of the string that -holds the beads are sealed. The sex of the baby is in- dicated by the color of the beads—blue for a boy and pink for a girl. ©Keystone View Company Easy Days for the Bricklayer “@(NNE brick in the hand is worth two in the pile,’’ so this bricklayer thinks. To speed up his work he made a small wooden shoot and the bricks slide down the incline into his hand. There is always a brick ready, and the bricklayer does not have to bend over to pick it up. His helper sends the bricks down. This is better than making the helper pile the bricks up at his side. It also saves the use of the hod. The bricks are conveyed to the upper floors by a small hoist. This brick-delivering device is the inven- tion of Major Frank Gilbreth, the Ameri- can efficiency expert.

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+ eye in eI wre Vibe Hoo Oe ee * pemeeeiensta ir pao oP cn peg ae EN Ae aA ere

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turns on the breeze whenever a

© Keystone View Company He Is Planning New Designs IGURED cloth of the cheaper grades is printed like the colored edition of your Sunday newspaper and the paper on your house walls. A copper printing-roll is used for each of the colors. There are as many rolls on the printing-press as there are colors in the cloth to be printed. The designer in the illustration above is shown planning and drawing patterns that it is hoped will please the taste of women on the lookout for attractive materials. Woven designs are used for the more expensive fabrics, but they are planned in the same way by the same men who plan the designs for the cheaper textiles.

Trying Out Goggles in Front of a Fan A bres buy goggles until you have But One wise dealer has put an electric fan on the tried them out in the wind. will the dealer let you do this? counter of his store and he customer buys a pair of gog- gles. By standing directly in front of the fan the wearer is able to tell whether the par- ticular pair he has on is suit- able. If the buyer owns a motor- cycle. and~ expects to dash through sandy places, the man behind the counter will oblig- ingly drop a bit of sand in front of the blades of the fan. No contingency that can be foreseen is neglected.

—— A Shower to Fit Any Bathtub peated bathtub can have a good shower-bath when this little at-

tachment is affixed to it. It is held to

Safety Guard for Punch-Presses PUNCH-PRESSES have clipped off many fingers and not afew hands. Since workmen’s compensation acts have been placed in effect in many of the states, manufacturers have taken greater care to see that machinery is well guarded. If they do not guard their machinery properly, their compensation insurance increases. Above is shown a new press guard that makes a sweeping motion across the front of the press just before the die descends. If the operator’s hands are in the way or under the die, they are brushed aside before the die strikes. This guard has been used for three years, and it is claimed that no accidents have occurred with its use. Five Jobs Accomplished on One Machine HOWN below is a machine that will keep three men busy, although they may be doing different jobs. It will do shearing, coping, notching, section-cutting, and punching. Five separate machines are combined in one unit and driven with the same motor. Each unit of the machine is independent of the other units. Five individual machines capable of do- ing the same amount of work would cost several times as much a as this machine. (Gas There is economy in space, operation, } power, and upkeep. aq /

the side of the tub by a small clamp, and connection is made with the faucet with a small length of rubber hose. The height of the shower is ad- justable and it will swing into any position desired. When a bathtub seat is used with the attachable shower, all the pleas- ures of a regular shower-bath can be enjoyed. It may be used also for washing the head without the neces- sity of getting into the tub. The tem- perature of the water must, of course, be regulated at the faucet

This Man Never Has to Hunt for His Glasses T= gentleman in the picture, Isaac F. Garner, of Calera, Alabama, has very good eyesight except for close reading. When he wore glasses dan- gling on a cord, they were fre- quently broken; when he put them away in a case, he was always losing the case. So he rigged up a_ head- piece consisting of a band fitting around the forehead and the back of the head, with small hinges connecting the front half with the back piece. A short rigid arm holds the glasses in place when in use, and when Mr. Garner is through reading, he merely pushes the glasses up on his forehead.

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VTim¥v (_____— “ © or August, 1921 This Flashlight Works with Air LASHLIGHTS are used to take photographs in dark places. The flashlight supplies the ‘‘actinic”’ light that is neces- sary for successful pictures. Certain substances give off a great amount of this light when they burn. The metal magne- sium is one of these substances. When brought to a certain tem- perature, magnesium wi!l burn rapidly—almost explosively. Magnesium powder is used in the flashlight holder here pic- tured. The powder is blown into a small flame. Blowing into a small rubber tube raises the magnesium powder from the hollow handle and sends it into the flame, which then produces a light that is rich in actinic rays. It Sifts Ashes by the Ton ‘THE machine shown below gobbles up ashes by the ton. The ashes are thrown into a revolving drum at the back of the machine. The very fine particles fall through and the larger particles pass on to another drum with larger meshes. Here another separation is brought about and the large pieces fall into a screw conveyor that revolves in a liquid medium. These conveyers are located in the inclined tank. Here the heavy matter, such as the clinkers, sinks into the liquid, and the lighter matter, such as the partly burned coal, is lifted by the conveyor to an outlet on the opposite side. Dangling from the Bicycle She Lowers Center of Gravity T first glance this looks like one of the most daring feats ever carried out in midair. Harry Peil, a European gymnast, re- cently thrilled a great crowd of people with his tight-rope bicycle trick. He rode across a street, from one high building to another, with a woman dangling from the end of an iron pipe attached to the bicycle. Although the trick appears very hazard- ous, it is not so dangerous as it looks. The woman hanging on the end of the iron acts like the lead keel on a sailboat. She pro- vides a low center point of gravity that makes it practically impossible for the bicycle to tip over. If the iron pipe were shorter, there might be another story to tell. For Chopping Wood with Your Feet OULD you rather split wood with your hands or with your feet? Which would fatigue you more? One inventor believes that you should be able to chop wood better with the strength of your feet, and for this reason a machine similar to the one pictured has been brought out. It is operated by means of a foot pedal. When the foot pedal is pressed, the heavy blade, mounted on an arm, moves downward with considerable force. The piece of wood to be split is held under this blade. When the foot is taken off the pedal, the blade returns to its normal position. Carry Your Hangar with You [' goes without saying that airplanes must be protected as much as possible from the elements. Sun, wind, and rain all help to shorten the life of a machine, and yet an airplane hangar is not always available. This has led an inventor to design a portable canvas hangar that may be carried by the aviator. It is really a tent that may be rolled up into a small bundle and carried in the fuselage of the machine. Celluloid windows are provided and doors that roll up are placed in the sides. The tent-hangar can be taken out of the machine and -put up in half an hour. a

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Ce ee eee nba tte eat a oh cea. i aerial x > “ pete Bembnge: Le ae IT a ROMA a = pn De moby SAY 2 a SR Da WW tease teint a8 sep pikepnains Ea. rms = he onl : 7 ee aa EAR SS page er ert SS Hair is Now Singed Electrically E are told that hair should be singed regularly to remove split ends; but heretofore singeing has been done with waxed tapers and there has always been the danger of burning the hair. Now, however, there is an electric singeing device, shown in operation in the picture above. It is made of alu- minum and has two arms joined by a thin quartz tube containing a resistance coil. An electric switch in the handle controls the current. When the switch is turned on, the tube becomes red hot in ten seconds. Care must be employed by any one using this instrument for the first time. He Whittled a Portiere from . Strips of Pine HERE is a man who must have a great deal of patience. It took him six months to whittle out this portiére with his trusty old jackknife. Each of the lengths seen in the picture ‘was once a long piece of white pine. The links of the chain were whittled out, and each one is a whole piece of wood without joints or flaws. At the top of each chain is a little round ball in a little cage that forms the upper terminal. The other end of the chain is ornamented with a carefully carved acorn. Thirty-five chains make up the portiére. This man has made many other ob- jects of art and usefulness from white pine. Is the Movie Way Quicker? EVENTH- and eighth-grade classes in nature study in a school at Evanston, Illinois, were recently asked to vote their preference between the text-book and moving-picture method of instruction. The movies received 170 out of 180 votes. Basing her conclusions on written les- sons, their science teacher reported that her pupils learned more about the Monarch butterfly in a fifteen-minute moving- picture than they did about the Black Swallowtail in six thirty-minute text-book Jessons with the aid of actual specimens. Making the Alphabet Interesting N° longer need the alphabet be taught in a monotonous singsong manner. It can be made interesting. Here you see a new alphabet machine that is really a toy. The child punches a key and a card springs up in front of him. On the card appears a large letter corresponding with the letter on the key punched, and a picture of some animal whose name starts with the letter in question; for instance, the letter “L” and the picture of a leopard. Every time a key is punched a bell rings —an added attraction. As soon as the key is released, the card it governs falls back into place. Popular Serence Monthly Curing Hiccoughs with Hot Water b hens pneumogastric nerve is respon- sible for hiccoughs. When it is agitated it causes the diaphragm to contract spasmodically. The nerve in question connects the stomach with various parts of the head—especially the ears. Air rushes up the glottis and hits against the epiglottis, causing what ‘is known as a hiccough. There are several methods used for calming the pneumogastric nerve. The picture above shows one of the latest that is very popular in London. The hiccougher puts his fingers in his ears while some one gives him hot water to swallow. The Whole Family Tricycles on This Machine ELOW you see a bicycle for an entire family—provided the family numbers no more than three. An _ enterprising father made this three-passenger tricycle, on which the whole family can take its Sunday ride together. Tt will be noticed that dad takes the lead. When a hard hill is approached, probably he has a pretty tough pull of it. One could readily imagine that with the three cyclists pedalling steadily a fairly good speed would be attained. It would not do, though, to de- pend too much upon the youngest member. The two rear wheels are connected with the back of the first bicycle by a small iron pipe. The rear handle-bars on the rear wheels serve merely to prevent fatigue. They are not used for steering.

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_- ~~ Ww Ve te NS ORO ctw August, 1921 © Gilliams Service Steel Cables Drive This Bicycle Ts chain that appears on most bicycles has been dispensed with in the unusual looking model shown above. In place of the chain two thin steel cables are em- ployed to transmit power to the rear wheel. To propel the ordinary bicycle it is nec- essary to bend over. Bending over is not necessary on this machine; the rider may seat himself as in a comfortable chair. He presses his feet downward on the pedals, and this unwinds the thin cable from a pulley on the axis of the back wheel. This happens at the time the cable on the opposite pulley is winding up. Making the Barrel-Head Stay On HERE is a little tool used in placing barrel-tops. The hoop that holds the top of the barrel in place is pulled tightly about the barrel before the final rivets are put in place. If this hoop is not put on tightly, the barrel- head is apt to come off during transit, with results that can be imagined. This tool grips both ends of the steel hoop. By means of the lever the ends are pulled together and held until they are secured. With this tool a man can place heads on barrels very quickly, and they are on to stay. Golfers, Here Is a Device that Casts the Tee CAREEUL golf-players take great pains to see that the tee upon which the ball rests is made just right. The sand is care- fully piled up into a small mound and the ball is laid on the peak. With the aluminum device below a per- fect tee may be made very quickly. The moist sand is placed in the cone-shaped cup and packed down tightly. It is ejected merely by pressing on a small plunger at the top with the thumb. After the sand has been pushed. out, the plunger is forced back to its normal posi- tion by a spring. The device is made of aluminum to prevent the moist’ sand from sticking to the sides of it. Hang Shelf Like a Picture - Fe you ever try to put up a shelf? Did you ever have the pictures in the next room fall off the wall through your hammering? Or did the plaster come down in lumps? No more need you have troubles such as those. Below is a shelf that hangs like a pic- ture. Take it out of the box and you will have it hanging on the wall in five minutes. The stepladder is all that is needed. The shelves are made of pressed steel nicely enameled and held with thin steel cables. The distance between the shelves is adjustable. How London Builds Her Roads N English inventor has brought tar- paper into use in road construction. Wooden blocks are first laid in the usual manner and covered with a heavy coating of tar. Heavy tarred felt is then placed over the bricks. This carpet is fastened to the wooden blocks with nails. After this, another application of tar is made and a sand-and-cement dressing is placed over it. This carpeted road has been used on a Thames river bridge in London for several months and it shows little signs of wear. It is, of course, important that road- mending in large cities be reduced to a minimum. Strengthen Merchandise Barrels with This Brace ANY millions of dollars’ worth of merchandise is lost annually by the collapse of barrels and boxes during ship- ment. Barrels containing heavy sub- stances such as sugar and cement are very apt to break and spill their contents if they are handled roughly. A crushing force applied to the center of the barrel strikes it at its weakest point, since there is nothing there to offer sup- port. William F. Meek places two sup- ports in the center of the barrel to prevent it from breaking during transportation. The cost of the supports is small, since they are made of wood. Abi)

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mineral Popular Science Monthly Housekeeping Made Easy The contents of this pot can’t boil over. Why? The lid is perforated throughout; as the liquid boils it rises through the perforations and then runs back through a hole to which a floating valve is attached The floor-lamp and the phonograph are here combined. The lamp is fastened to the lid of the phono- graph. There are two hinged sec- tions that can be swung upward when you wish to put on a record a Here is a can-opener equipped with a cogwheel for guiding the knife. The wheel travels along the side of the can‘ just below the rim; the knife easily cuts through the top of the can Why tire yourself whipping cream, beating eggs, or mixing light batters? There is now an electric attachment that will do the beating for you. A lever controls the starting and stopping, and regulates the speed of the blades Rubber bulbs on atomizers are apt to dry up and crack. Hence we now have the metal bulb shown above. It consists of two tele- scoping cylinders of aluminum. A spring re- turns the outer cylinder to position The lower part of this phonograph cabinet contains the mechanism and the turntable. What’s in the upper part? A moving-picture machine. Thus you can have movies and music at home at the same time CURVED BLADES Four’ sharp blades twirled inside a grape- fruit will cut out the tough, seedy center. A bag of soap in the dish-mop will create plenty of suds for your dish-washing. Any odd Instead of a wrist-watch, the dressmaker now wears a wrist pincushion. ion is mounted on a flexible Inside the spout of this coffee-pot is a strainer that can be The cush- You need not touch the grapefruit at all during the process pieces of soap —even the stub of a shaving-stick—should be put in the bag, eliminating any wastage metal-bracelet that is snapped in place on the wrist. It is loaded with pins taken out and washed every time the coffee- pot is washed

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August, 1921 Keeping Up with the March of Science Facts for the man who wants to know Gasoline Graded by Color coven grades of gasoline are in the market, greatly differing in their effectiveness, but so similar in appearance that even the eye of the expert cannot detect the difference. Since the prices are graded according to the quality of the gasoline, dishonest dealers make consider- able extra profit by selling to their tran- sient customers inferior gasoline at the price of superior grades. Several important producers of gasoline in England and elsewhere are considering the plan of giving to each grade of their product a distinctive color that will make it possible to distinguish it at a glance. A method has already been evolved of so coloring gasoline that it can easily be dis- tinguished. The coloring has no deleteri- ous effect and causes no sediment. Any attempt to mix or blend two or more grades would be detected by the alteration of the shade. Why Car-Wheels Break HE breaking of wheels of railway-cars is a frequent occurrence. It constitutes a serious menace to life and property and at the same time an important item of expense. The Bureau of Standards undertook an investigation of the cause of breakage, and after exhaustive research ascertained that the relative overheating of the car-wheels at their periphery by the prolonged applica- tion of the brakes while descending long grades was principally responsible for the breaking of the wheels. The overheating caused strains due to unequal expansion between the peripheral parts of the wheel and the cool central parts which only twelve of the twenty- eight wheels tested could withstand with- out breaking. Forms of Color-Blindness OLOR-BLINDNESS, a natural and congenital defect, has three distinct known forms—total color-blindness, in which color cannot be distinguished at all, but only light and dark; partial color- blindness, in which red is mistaken for green, or black for brown; and a form in which the afflicted person can discern the primary colors but not intermediate shades and frequently is unable to distinguish between blue and violet. It is a remark- able fact that persons afflicted with color- blindness often have better, clearer vision than persons not so affected. It is estimated that in England four per cent of the male population is afflicted with color-blindness, but only one half of one per cent of the female population. The percentage of color-blind individuals is especially great among Jews and Quakers. The defect often runs in a family for many generations, and, although it is confined to the male members, it is transmitted through the females. The daughters of color-blind men invariably have color- blind sons. The cause of the defect is not yet defi- nitely known. Temporary attacks, arising from old age, the use of drugs, alcoholism, and excessive smoking, are sometimes cured; but no remedy is as yet known for the congenital type of color-blindness. Beautifying Concrete Houses OUSES built of reinforced concrete undoubtedly offer many advantages, but the naked ugliness of their outside offends our esthetic sensibility. An English architect, Professor Beres- ford Pite, in a recent lecture, strongly ad- vocated the covering of houses of rein- forced concrete with glazed or unglazed ceramic tiling of any desired color or shade. Such tiling, Professor Pite contends, would materially improve the appearance of con- crete houses, and, being impervious to moisture, would give additional and per- manent protection to the structure. Can Seasickness Be Cured? i's anybody asked you what kind of waves cause that terrible sensation known as mal-de-mer, you would probably say it was the short, choppy variety. But you would be wrong. It’s the long, billowy kind that does the damage. This has been determined in the Na- tional Physical Laboratory at Teddington, England. Here a band of public-spirited workers are doing their utmost to discover the secret, and at the same time the cure, of seasickness. To carry on their research, they have a wave-making machine equipped to produce electrically all the kinds of waves known to seafarers. The waves are produced in a 750-foot tank, and the velocity and volume of each wave are carefully measured, as well as the effect on wax boats sixteen feet long. These measurements are recorded by extremely sensitive instruments. The object of all this experimentation is to determine what kind of ship can success- ‘fully combat the action of seasickness- producing waves. Magnetic Steel Tests ESTING steel for the presence in it of cracks and air bubbles has heretofore been a difficult and complicated operation, consuming much time. Recently a new method, invented by an English engineer, was tried out with great success. ; The steel block to be tested is immersed in petroleum that contains very fine iron filings in suspension. The small particles of iron are attracted by the residual mag- netism in the steel and adhere to the block. Where there are bubbles or cracks the lines of force formed by the filings will show breaks and dark portions. 69 Corncobs Have Their Uses Or a few years ago the farmers in the corn belt of the United States con- sidered corncobs as useless and undesirable refuse. They used them for fuel, but only when wood or coal was scarce. Recently many important uses have been found for the corncob, which is no longer allowed to go to waste. Cellulose, which is the principal component of the corncob, is employed in the manufacture _ of various explosives. From corncob pulp certain grades of paper may be made, and a valuable sub- stance, furfural, may be obtained which is used in the manufacture of certain adhe- sives and forms the basis of a beautiful green dyestuff for silk. It is also an im- portant reagent in the chemical laboratory. Deceived by the Eclipse earners in a corner of the Croydon aerodrome in England is a lighthouse that works automatically. When the light of the sun fades in the evening, the power- ful lamps of the lighthouse are turned on by a mechanism actuated by the electric re- sistance of a light-sensitive selenium cell. When the moon moved across the disk of the sun during the annular eclipse on April eighth of this year, gradually shutting out the light, the selenium cell proportion- ately lost its conductivity and set in motion the mechanism that turned on the lamps of the lighthouse. As the moon receded from the disk of the sun and the light became stronger, the growing conductivity of the selenium cell soon caused the lamps to be turned off. Sweet Potatoes Are Valuable O* the specifically Southern products of the American soil, cotton and tobacco have long ago won reeognition in the markets of the world. The peanut is rapidly gaining in popularity and economic importance, and now the humble sweet potato is striving for recognition. A scientist connected with the Tuskegee Institute for negroes in Alabama has made a special study of the sweet potato, and, as he stated at a hearing before the Ways and Means Committee of Congress, more than one hundred different sweet-potato prod- ucts have been developed to date, all of them valuable for food purposes. How Raindrops Are Formed FOR the purpose of verifying or disprov- ing theories concerning the manner in which raindrops are formed, Dr. W. J. - Humphreys made a,careful investigation, the results of which he submitted to the American Physical Society at a recent meeting. He expressed the opinion that humid air, ascending, becomes cooled to

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Sos z ape Oe 73d Fe = s kaa AEE REET BE gouce os Sa ace + Aaa S — a EES _— : —ieepaties - paspuihstegene neg ae was igh ye ane jb arate Na SE = HR eRe See ss SI ae eo eS SES ee . zs hi et ta - a — _ — _ —_ ——— = the condensation point as it meets colder strata of air. When that point is reached, the water vapor condenses around the nuclei of mineral or organic origin sus- pended in the air, and forms droplets. The drops thus formed in the Jower part of the cloud attract the greater part of the nuclei carried by the warm air still ascend- ing. Hence the number of nuclei in the upper strata of the cloud will be so small that sufficient vapor can condense around each of them to form a drop heavy enough to fall to the ground. In their descent many of these drops may combine with others—hence increasing in size and weight. This coalescence is prob- ably facilitated by the electric charge that the drops usually carry. Some Plants Like the Cold Wer some tropical plants freeze at a temperature of about 39 or 40° F., other plants can endure the terrific cold of the arctic winter night without injury. Alpine flowers thrive in the region of snow and ice, developing blossoms, although they are frozen during the night and the greater part of the day and thaw out only for a few hours in the middle of the day. In Siberia, where the temperature fre- quently drops to 64 degrees below the freezing-point, many hardy flowers and trees grow in profusion. More Wood Alcohol HE destructive distillation of wood produces wood alcohol, together with acetone, acetic acid, and other substances of industrial value. The increasing scarcity of wood and the constantly growing demand for wood alcohol made it desirable to increase the yield of this product. The problem was taken up by the United States Forest Laboratory at Madison, Wisconsin. After a number of trials it was ascer- tained that the addition of 1 per cent of sodium carbonate to the wood increased the wood-alcohol yield about 50 per cent, without diminishing the yield of acetone and acetic acid. The wood should either be thoroughly impregnated with sodium carbonate in solution before it is distilled, or, if in the form of sawdust, it should be thoroughly mixed with the dry carbonate. Sound Location by Birds NAABLY all birds seem to possess an extremely acute sense of hearing, and some of them have a faculty of determin- ing the direction of the sound. This is of particular interest in view of the fact that the birds have but a single middle ear, flanked on each side by a drum membrane. Birds also lack the highly developed outer ear of the mammals that is believed to be a great aid in locating sound. Some scientists are of the opinion that the keener sense of location of sound in birds may be accounted for by the greater efficiency of their eardrums, which are in- timately connected with the same middle ear. Prize for a Humane Trap HE New York branch of the American Society for the Prevention of Cruelty to Animals offers a prize of $500 for the best humane trap for capturing fur-bearing animals. This effort of the Society to re- lieve unnecessary suffering of wild animals ought to meet with a wide response. The competition is open to all. It closes on October 1, 1921. Send your ideas to George Foster Howell, 187 Windsor Place. Brooklyn, N. Y. Guarding Against Radium OON after the discovery of radium it was learned that it possessed to a high degree the power to destroy living tissue. This power is the reason for its extensive therapeutical use as a destroyer of malig- nant organisms and tissues and at the same time the cause of the serious dangers con- nected with the handling of radium. Now that the nature of radium is more fully understood, means have been found to safeguard the life and health of persons treated with radium, and of the scientists, doctors, and nurses handling it. A patient in an infirmary at Sheffield, England, who was undergoing treatment for cancer of the tongue, inadvertently swallowed the capsule containing the radium with which he was treated. The doctors feared grave consequences, but did not wish to remove the radium by a surgi- cal operation. Instead, they took X-ray photographs of the patient every hour, watching the progress of the radium as it passed first through the alimentary canal, then through the stomach, and then slowly through the intestines. They were ready to operate if the capsule lodged in any spot for more than one hour. Fortunately, the capsule progressed slowly but without stop- page, and was expelled thirty hours after it had been swallowed, without having done any harm to the patient. To Trace Ground-Water ie is important sometimes to ascertain the origin and flow of ground-waters, which feed springs, ponds, or swamps or are derived by seepage from rivers, canals, or other large bodies of water. In some cases it‘ may be desirable to ascertain the existence of underground connections between rivers and other watercourses. Usually the most reliable results are obtained by the use of certain chemicals or dyestuffs that are dissolved in the water, are distributed through the underground channels by the flow of the waters and carried sometimes for many miles. The presence of these chemicals or dyes in the water can be determined by analysis or, in the case of certain dye- stuffs, by the color which they impart to the water. One of the most efficient aids in tracing underground waters is fluoresceine, a coal- tar product of brilliant orange-red color, which is easily soluble in alkaline water and imparts to it a brilliant green fluorescence. So powerful is this substance that one part of it, dissolved in 40,000,000 parts of water can easily be distinguished with the naked eye, and with the aid of a long tube of 70 Popular Science Monthly colorless glass even one part of fluoresceine in 10,000,000,000 parts of water can be detected. Water that contains free acid cannot be traced by this dyestuff, because the acid destroys the fluorescence. For this reason it is not suitable for tracing water percolating through peaty soil. In making the tests, the calculated quantity of the dyestuff is dissolved in a small quantity of alkaline water and the solution is poured in a single charge into the water the underground flow of which is to be ascer- tained. All springs and underground waters in the direction of the suspected flow should then be watched - and samples should be taken at intervals to be tested for any trace of fluorescence. Disease Destroys Glass wet only animals and plants are sub- ject to disease: inorganic matter also suffers. The corrosion of metals and the gradual disintegration of rocks and minerals by weathering, dehydration, and direct chem- ical action do not, properly speaking, be- long in the category of disease of inorganic substances. But there are certain other peculiar phenomena, probably caused by the agency of bacteria or microscopic fungi and algae, which may rightfully be con- sidered as diseases. Such phenomena have been observed in iron, steel, zinc, tin, and aluminum, and in certain sandstones, bricks, mortars, concretes, and glass. Recently it was reported that the famous stained-glass windows of York minster, one of the most beautiful cathedrals of Eng- land, had been attacked by a peculiar dis- ease that in time threatens their destruc- tion. Small holes develop in the glass. These holes grow deeper and cause the sur- face of the glass to flake. Some parts of the glass have become as thin as tissue- paper and crumble at the touch. Neither the cause of the phenomenon nor a remedy has so far been found. Room Temperatures A*™ expert on heating and ventilating has compiled a tale of suitable tem- peratures. Living-rooms should be about 68° F., while bathrooms require between 70 and 85 degrees. Sixty-five degrees is sufficient for churches and from 60 to 64 degrees for lecture-halls, while public buildings should have a temperature of between 68 and 72 degrees, and schools about 70 degrees. For entrance-halls and vestibules a tem- perature between 54 and 60 degrees is recommended; for gymnasiums 60, for swimming-halls 68 degrees. Hospitals should have a general temperature of between 72 and 75 degrees,’ sickrooms 72, and operating-rooms from 70 to 90. Factories and shops are best kept at 65 degrees; boiler-shops and foundries only require from 50 to 60, machine-shops from 60 to 65, while paint-shops require about 80 degrees. From 50 to 64 degrees is con- sidered warm enough for prisons, probably in order to make them less attractive in cold weather.

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i i MO ct mn t Ne is r is of 5 ly at n- in August, 1921 3ROKEN-OUT RAIL SECTION - Tools and Machines for Higher Efficiency HYDRAULIC PISTON SWING -QUT’ RAIL CLAMPS This portable rail-bender is intended for use in railway construction. It has inter- changeable formed bending blocks that prevent the buck- ling of the rails. The yokes are hinged and make it possible to introduce rails sidewise RADIAL CUTTER Vitel ered Rts ic UBLE-HINGED ARM A portable hydraulic press used to extract crankpins in locomotive wheels and other heavy machinery. The ram of the press is sent forward with hydraulic pressure de- veloped by a small hand pump; 150 tons pressure may be developed Speed, safety, cleanliness, and efficiency are achieved by this can-opener, which will handle cans of one- gallon size or smaller, twelve a minute. The knife does not revolve until in position and a clutch is thrown in 4 ROUGHING AND = FINISHING CUTTERS { 4 wcessssensnsacioansivee Ny » - " / a ROTARY TA “ee In this continuous milling-machine the work is clamped to a rotary table. The picture shows automobile cylinder- heads milled from the rough casting. The left spindle is for roughing; right one is for finishing the With the machine shown here one operator tapped 700 holes an hour in cast-iron cylinder-blocks. This includes the time required to change the taps to three different sizes and to turn the block BUCKET CAMS rey Illustrating the manner in which the dis- charger, resting on its own track, tilts the buckets of the link-belt coal-conveyor. The flange causes the buckets to tilt Special steel that takes great hardness, holds a keen edge, and does not scratch, enters into the construction of the hand scraper shown here. The scraper blade is held in position by notched clips and is exchangeable Shear gates of the type shown here are used exten- sively in sewage and _ filtration plants, where the pressure of the liquid is compara- tively light and always in the same direction With this machine one hun- dred wedges can be cut from a block of wood in one min- ute. The plane of the circular saw has an up-and-down and an oscillating motion ¢ RAN! jPLUNGERS Briquettes composed of coal screenings, small particles of coke, and 6 or 7 per cent of a_ binder ‘are means of fuel- saving. This machine, with a pressure of 100 atmospheres, produces 3000 pounds of briquettes an hour

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etn) aa EE Popular Science Monthly Worm Automobile Parts Saved by Plating A remarkable method of repairing machine parts that has unlimited industrial possibilities HEN you electroplate, you coat with a valuable metal, such as gold, silver, or copper, an article made of a baser metal. The article to be coated is connected with an electric circuit and immersed in a chemical solution so as to constitute what is called an electrode—that is, a terminal to or from which the electric current flows through the solution. Another electrode, which consists of the metal to be. deposited, is im- mersed in the same bath and con- nected with the circuit. Switch on the current and a chemical action takes place. Minute particles of the metal are detached and deposited upon the article to be coated until the requisite thickness is obtained. The method is known as “electro-deposition.”” Simi- larly, electrolytic copper (which is the purest form of copper) is obtained by allowing the process to continue until solid bars have formed. This principle has now been applied to the deposition of iron with such satisfactory results that a coating of iron one twelfth of an inch thick can be -By P. J. Risdon English correspondent of the Popular Science Monthly deposited upon an iron or steel object of cylindrical shape. Because iron so very readily oxidizes or rusts, not only was it difficult at first to secure the adherence of the coating, but even when that was accomplished spots would rust beneath the deposited film. This led to exhaustive experiments, as a result of which means were evolved for so thoroughly cleansing and pre- paring the surface to be coated as to insure perfect adherence without fear of subsequent corrosion beneath. This will perhaps be better understood by considering what happens when iron is painted. If an iron bar, slightly rusted, is rubbed so as to appear per- fectly clean, and is then painted, sooner or later the paint will scale off in patches where the metal has con- tinued to rust beneath the protective coat of paint. Again, in cheap copper- plated articles rust appears in spots, causing the copper deposit to flake off. Now painted ironwork can be re- painted periodically and coppered articles can be recoppered, but when we come to depositing a compara- tively thick coating of iron upon an iron or steel article, we encounter a totally different problem. The pri- mary object in view was to build up the worn parts of motor vehicles to their original size and so avoid consigning them to the scrap-heap. During the war, when in England and France spare parts were often un- obtainable, vehicles were driven until they would run no longer. They were brought into the workshops in a de- plorable condition. Bearings had been hammered and packed up. In a case within the writer’s personal knowledge all the bearings of a certain car were packed up by strips of match-boxes and newspapers, and that was only one of numerous instances. When such expedients are resorted to, the effect upon gears, for example, is disastrous. Once out of true engagement, gear teeth, which would otherwise give satisfactory service for years, grind and wear with astonishing rapidity. How to Carry Out the Wonderful T= proeess of depositing a coating of iron that has been successfully carried out in England and France is as follows: The article to be coated is first cleaned with gasoline to remove all oil and grease. It is then immersed for twelve hours in a bath containing a scalding solution of caustic and washing soda at a temperature of 194° F., after which it isrinsed and cleaned thoroughly with wire brushes. The portions of the surface that do not require a deposit are then well coated with a mixture of bitumen and paraffin wax. The article is next wired up as a negative electrode, and immersed in another solu- tion’of soda similar to the first, but at a normal temperature, a piece of sheet iron being used as a positive electrode. A cur- rent of from 30 to 50 amperes is turned on for three minutes. The part is lifted out and immediately washed in water before it has time to dry, and then it is dipped for a few seconds in a strong solution of nitric acid (equal parts of acid and water). Producing the Fine White Surface It is next made the positive electrode in a cold solution of sulphuric acid consisting of 25 per cent of acid to 75 per cent of water, a current of from 30 to 60 amperes being switched on for about three minutes, reversed for three minutes, and reversed again for three minutes. This produces a fine white surface when cleaned. During this part of the process a porous screen is placed between the article and the other Electro-Deposition Process electrode to prevent gas (given off at the negative electrode) from disturbing the solution around it, as any movement of the solution impairs the effect. When lifted from this solution, the article is immediately washed again in running water and as rapidly as possible transferred to the depositing bath or vat. -In this it is suspended as a negative electrode again, the positive electrode consisting of Swedish iron wire of .16 standard wire gage woven into the form of a cylinder and placed in the vat so as to surround the article concentrically. The solution is of ferrous ammonium sul- phate at 68° F. It is kept gently agitated, and changed every three or four days. ’ The time taken to complete the deposit varies from-one or two days to a fortnight, according to the nature of the work. By this means not only is perfect adher- ence ensured, but, as magnified sections show, the coating is virtually homogeneous with the metal of the article itself, for it is almost impossible to chip it off with a hammer and chisel. The layer presents a smooth surface that can be filed or ground and beautifully polished. An article so treated can be made red hot without dete- rioration of the deposit.. After completion the deposited layer may be hardened, if required, by a process known as case-hardening, in which the metal is heated and carbonized. Photo- graphs of. magnified sections show that in some instances the carbon penetrated through to the original metal, obliterating 72 fis. every trace of any dividing lines. In a small shop of sixteen hun- dred square feet area the worn parts of thirty-six vehicles a week were satisfacto- rily repaired, which in six months comprised six thousand different items. Larger Repairs May Be Possible In many cases, cars returned for repair a second time enabled examinations to be made that proved that the built-up parts gave satisfactory service. It is hoped that _the process. may be found applicable to large and to fast running shafts subject to torsion, and to articles of other than cylin- drical shape that have hitherto resisted satisfactory treatment. Among other essentials, it was found necessary to exclude dust and to maintain the shop at an even temperature, since low temperatures caused the deposits to be- come brittle and to adhere badly. A uni- form current density is also of importance to insure continuity of deposit, since varia- tions in the current cause rings of growth. The variety and number of cleanings that articles have to undergo are perhaps somewhat bewildering and may appear at first sight rather laborious; but it must be remembered that an absolutely clean sur- face is the first essential for adherence. It required great skill and patience and much experimenting to ascertain the best methods of treatment, and the inventors may certainly congratulate themselves on having achieved something that should prove of great commercial value.

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August, 1921 FRE pee agen ae ao “The First imporr 1s fo clean the a MS © Modern Publishing Company Electro-Deposition of Mr. Davis’ drawing shows in detail the process for coating metal with iron now being used extensively in England and France in the automobile-repair trade. ; It is possible by this process to deposit a coating of iron of one twelfth of an inch on an object of cylindrical shape. EOperation Zic/e ro be treated In a gasoline bath ss ‘ - BI? Process i Wtion not reguiring repair coafte With amixture of filersea & paraftin sa (4 Pn ( a g . Pg f_ : Ey se : jx ; Switchboard, y~ | | A ( ~~ fast | 10, -Mel-) essehs le muesa ey whieh the otticle is suspended as a negative electrode Fhe other electrode is formed of wound Swedish iron wire lmunersed mm ferrous QINIMOMIULIT. Sulphate. Se typ ' “ ~— 4 — = —_ — = = — — — —_ —_ —— A ets Drawing by G. H. Davis Iron on Metal Parts It is necessary first thoroughly to cleanse the article to receive the deposit, after which a carefully worked-out process is followed in which the article to be coated is the ‘ negative electrode and a piece of sheet iron acts as the positive 73

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the New Car Accessories Pictured on These Pages With this invention of a New York manufac- turer it is possible to aline pistons and true up wrist-pins with per- ae ea fect accuracy. Rod ae SY o . bearings may be alined =. ee before they are placed Somat F on the automobile oe ge us en into extensive use. An adjustable chute for dumping gravel or sand fits in the side of the end gate; when a sliding door in the gate is open, the ma- terial flows through the chute to the side of the road In the work of excavating for building operations, the tractor is fast coming UNIVERSAL- JOINT SPRING Here two tractors are shown dragging scoop shovels, which dig up huge amounts of dirt and carry it away With this oil petcock opener, which is very easily installed, you merely need turn a handle by the running- board to learn how much oil you have. The device is rattle-proof bee oe In the new hydrometer shown above the meas- - uring float is prevented from sticking to the side of the tube by two celluloid rings with studded points, thus insuring an _ accurate reading Popular Science Monthly Automobilists—Don’t Miss ME ___ FLOAT The problem of carrying a spare giant pneumatic tire on one- and two-ton trucks is solved in the instance shown above by placing it between the driver’s cab and the front end of the tank This shack-ab- sorber does not re- quire the changing of any part of the spring or axle con- struction; it is also THERM METAL pes es VAL SS SS A/A AS fini PUSH-BUTTONS This is a diagram of an_ electrically operated indicator to show the driver behind you which said to add to the For removing wire wheel- smart appearance hubs and brake-drums from of the car —besides automobiles, this automatic which, of course, it grip-puller was invented; it it is an excellent requires only one man to shock absorber operate it instead of the two formerly necessary; it comes equipped with two sets of pulling jaws way you are going. A new gasoline meter oper- The indicator’ is ates on the principle em- placed on the bodied in thermostatic metal: _ license-plate, and is it allows of a rich mixture of operated by push- gasoline in starting, but after buttons on the the engine has operated for a dashboard period it automatically turns the needle-valve down to a lean mixture

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August, 1921 and motor-trucks the Monthly endeavors to help its readers solve problems of maintenance and repair. there must be special cases that are not cov- : When You Want Expert Advice About Your Car N these pages of ideas about automobiles Popular Science But write. ered, and we invite you to write to the Auto- mobile Editor and let him advise you. If you wish to know more about the devices pictured here, or if you want to ask questions, Some answers are given on page 78. OSCILLUM ~. cs _ CABLES TO ENGIN Install this spark-plug tester on your dashboard. Not only does it tell you whether your plugs are working properly, but it also intensifies the spark and increases the engine power. Valve-grinding and carbon-cleaning are also greatly reduced To protect his face from windburn this motorcyclist made himself a mask. The front of it consists of two celluloid sections joined in streamline formation. The head nart is of wire netting Glass side pieces have at last been standardized; the ones shown above can be fitted to forty different kinds of touring-cars, thus turning them into sedans. The glass panels above the doors open with the doors Here is a signaling system that should reduce accidents. Three handles control three disks. One has “stop’”’ printed on jit; another has an arrow pointing. to the left; the third bears an Let this small tank oil your springs for you; attach it to the edge of the leaves at some con- venient spot and fill it with oil. A piece of felt fits between the edge of the leaves and the. oil- tank; it allows the oil to seep through evenly A tractor is not an easy-riding vehicle; hence we now have an air- spring seat. It has an inner tube — like an automobile tire—that. is filled with air; the tube absorbs most of the shocks arrow pointing to the right PISTOGN"GROOVE’ Carbon that gets into piston This motor-truck is built to haul almost anything. The front part has seats for passengers; the middle sec- tion carries merchandise; the rear is reserved for animals. Here you see a race-horse en route grooves is hard to remove. Now, however, there is a tool for doing it. You place the curved section around the groove, grasp the handles, and move them back and forth 715 - No longer need the peanut and pop- corn man push his stand through the streets. He may attach it to his flivver in the manner shown above. On Sun- days, however, he leaves the stand at home

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40FT GIRDERS . \ie —~— a UME 2, ] __(TEBODY - ,— a nn ee _ ae ee Pk STEEL FRAME With a truck only seventeen feet long, this is how a contractor managed to carry steel girders more than twice that length It Carries Forty-Foot Girders OME people would think it an impossible task for a motor-truck with a seventeen- foot body to carry forty-foot steel girders. Yet this was done with the truck illustrated. The owner of the truck built a separate steel framework over the top of the cab and braced it to a horizontal crosswise angle-iron, riveted to the front end of the truck-frame. The steel framework that is built around the cab permits long girders to be carried by resting them in an inclined position, sup- ported by the end of the body platform, the front end extending over the cab. The body is made two feet wider than the cab and the front end is left open. Removing one of the cast-iron sleeves that form the cylinder walls. of the features of the new engine Popular Science Monthly | Revolutionizing the Engine WELL known company has introduced a motor- truck engine with several features of design that bid fair to become popular, also a revolutionary transmission design by which both speed and pulling power are in- creased. The new transmission provides speed in direct drive as well as pulling power in the lower gears that does not necessitate an engine of excessive size. The increase in speed is obtained by a more highly geared rear axle. The extra pulling power is furnished by giving the countershaft of the transmission an extra gear reduction. The transmission countershaft has two sets of constant mesh-gears of different ratios instead of one. These are controlled by an extra lever, giving the truck two extra power ranges, each with a three-speed forward and a reverse direct drive remaining the same. Approximately 50 per cent more speed, in direct drive, has been added by this two-range transmission, and 30 per cent more pulling power furnished through the low range of transmission. Removable cylinder walls of the “wet”? type are a feature of the new engine. These are in the form of cast-iron sleeves that are pressed into the cylinder block. Better cooling is assured, since the water circulates immediately around the walls. There is also the economy of replacement. Replacing the sleeve is here a simple matter, done without removing the engine. The valve-lifters and rollers are inacase. Access to this is through a hand plate beside the engine. When the assembly is removed, access to the crank is had without removing the oil-pan. In the cooling system the engine has a pump and thermo-siphon action, the pump being mounted high on the engine so that the water is thrown directly around This is but one 2 the firing-chamber. Does the Spark-Lever Bricks Dumped in Stacks SUALLY, when a load of bricks is dumped, you can hear the rumble for blocks. Some of the bricks are broken, and the remainder must be collected and stacked up. ~All this annoyance is avoided when the truck shown below is used. The body of this truck, filled with stacked bricks, is lowered to the ground by means of a cradle that moves back and forth on the frame. — This cradle operates in such a way that the demountable body travels in a curve and lands on the ground in a vertical position, all bricks intact. The side of the body that now becomes the bottom is © held.in place by two iron pipes. When these are re- moved, the bottom is re- ‘leased; thus, when the truck resting on the bottom. The three- sided body was then swung back into place and a new fourth side substi- tuted for the one left behind. The power is derived from the en- gine of the truck itself. And the driver operates it from his regular driving seat. Mean Anything to You? N ordinary driving the position of the spark-lever need not be changed except for unusual road conditions after it is once set to run through a considerable range of speed. This con- dition is best found through adjusting and experimenting with the range adapted to each type of car. The “knock” from an en- _ avers gine laboring uphill is due to the fact that the spark occurs on the compression stroke, and the explosion meeting the piston coming down, tries to force it, thus producing a sharp metallic thump. One of the best ways to learn the proper use of the spark-lever is to drive at a steady speed, no matter what the road conditions, continu- ally watching the speedom- eter to see that it maintains pulls away, it leaves behind an oblong pile of bricks, The body is swung over until it lands on its side. The side is released. and left behind with the load of bricks 76 a consistent speed.

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~ aS. Re ft ww Nas FFT Be Ow eh 0 CO August, 1921 Tools for Truck Repairs A dollar in time for maintenance saves many for repairs By Joseph Brinker the labor turnover. ‘‘~ WORKMAN is known by his tools,’’ runs the old adage. Specially important are the tools used to repair the highly specialized machinery of a motor-truck. In this article—the fifth in the Popular Science Monthly’s motor-truck series—Mr. Brinker takes up the proper equip- ment for keeping an up-to-date motor-fleet in condition, going into detail about the right tool for repairing each part, and showing how the installation of such an outfit reduces OR every three dollars spent on a motor-truck, one dollar goes for maintenance. The lack of one dollar spent on maintenance at the proper time may mean an unexpected break-down on the road and a loss of from ten to twenty-five dollars in operating income or the expen- diture of an equal amount to get a second truck to complete the work of the first. Thus repair costs exert an important influence on total delivery costs. Truck-owners have learned that the truck is an ex- pensive and complicated piece of mechanism that can be taken care of only by adequate repair equip- ment. Adequate repair equipment may be divided under the two main heads of machinery and _ tools. Machinery is generally considered as apparatus permanently fixed to . the shop floor, such as drill-presses, lathes, grinders; tools are the more or less portable objects, such as electric drills, special wrenches, and fixtures. , The amount of machinery and tools required to maintain motor- trucks depends to some extent on the number of different types and sizes of trucks used. It is impossible to give a set rule that so many trucks require such and such equipment, although there are certain fundamentals in the selection of equipment that cannot be ignored. Unless a concern owns five or ten trucks, it is possible that maintenance repairs can be done more cheaply by an outside company or service station. But, once a company makes its deci- sion to carry on its own truck-repair work, it should be entered into whole- heartedly. Halfway methods and quib- bling about the cost of installation are bound to result in dissatisfaction. The equipment for a small repair- shop sufficient to maintain from five to ten or more trucks should include a lathe; a drill-press; a grinder; a forge; an anvil; a welding table and welding apparatus; an air-compressor outfit; a large arbor press; an overhead crane or track with hoists and carrier; a clean- ing-tank for parts; one or more engine Here is another device that will save the time and temper of the high-priced auto- mobile mechanic This little device, called a wheel-puller, will. remove the most obstinate gear from its shaft stands; an axle stand; perhaps an engine burning and running-in ma- chine with fittings and tool equipment consisting of a valve-lathe; a connect- ing-rod jig; a piston-vise; a crankshaft straightener; a bench arbor press, and miscellaneous hand tools, wrenches, etc. The work that can be performed by such machinery and tools is fairly well understood. A lathe is practically essential. It may be used to produce odd pieces that cannot be ordered from stock, such as bearing bushings or bolts with unusual diameters or threads. A drill-press is a most convenient piece of apparatus, for by it prac- tically all sizes of holes may be drilled. Engine stands with adjust- able frameworks permit the entire engine blocks to be turned around at will. A cleaning-tank, for re- moving dirt, grit, or even paint from parts on which work must be done, is another time- and labor- saver. Axle stands, arbor presses, and welding apparatus all have their place. A heavy truck axle is A Typical Up-to-Date Automobile-Repair Shop 1, engine-testing stand 2,3 engine stands 11, large drill-press 77 5, tutret lathe 6, oil-grooving machine 4, lathe 7, small arbor press 8, small drill-press 9, large arbor press 10, trunk box 12, acetylene-welding outfit

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a most unwieldy thing to handle, unless it can be held rigidly in place and a definite system followed in dis- assembly and repair. Arbor presses can be used to straighten bent shafts and for other work. Special socket wrenches for getting at bolt-nuts in inaccessible positions save much time and temper. Small gear-pullers come in handy when gears are obstinately stuck on With an engine-stand the repairman can turn the whole engine to any position that it is convenient for him to work on _ racy by haphazard methods. their shafts. Piston-inserting devices, spark-plug testers, battery testers, and the like are all handy tools that help to cut down the total cost of doing jobs. As the size of a truck fleet increases, truck maintenance becomes more and more of a science in which accuracy must supersede guesswork and speed must replace slow- ness. In making small indi- vidual savings, the yearly savings may surprise the truck-owner. It is impossi- ble to secure speed and accu- Granting that some mechan- ics are more skilled with their hands than others, the use of adequate machinery and tools makes it possible for the skilled worker to increase his output without affecting its quality. With adequate equipment the average mechanic can do far better work. He cannot do his best work when he lives in constant fear of being discharged; for - seeing men coming and going has a psychological effect that tends to dis- concert a mechanic’s efforts. Then there is other equipment, neither machinery nor tools, which has a direct bearing on maintenance costs. Portable gasoline-tanks permit the fuel Pepular Science Monthly Special cleaning-tanks, in which cleaning com- pounds and hot water or steam are used, cleanse truck parts of dirt and grease quickly, cheaply, and thoroughly to be carried to the trucks. Savings in time and money may be made by an adequate oil-storage system. One truck- owner, using approximately one hun- dred dollars’ worth of oil a week, saved $260 a year in oil by the introduction of permanent tanks with convenient draw-off plugs and drains. Determining Battery Poles Q.—Can a voltmeter be used to determine the negative and positive poles of a battery and if so, how?—J. B. B., Chicago, IIl. A.—A voltmeter can be employed to determine battery poles by touching the voltmeter poles instantaneously across the circuit. If the needle moves up- ward in the normal direction on the scale, the other end of the wire leading from the positive terminal of the volt- meter identifies the positive battery terminal. The other terminal must be the negative one. If the needle of the voltmeter does not register, it indicates that the connections must be reversed. Advantages of Four Valves Q.—Please explain why automobile engines with four valves to the cylinder instead of two give more power.—J. H., New York City. A.—The total power that can be developed by a gasoline engine depends upon the amount of gas it can burn. When four valves are used for each cylinder, it is possible to get the in- coming fuel and the burnt gases out of the cylinders more quickly. This also results in a smaller admixture of dead or burned gases with the incom- ing fuel so that the explosive power of any given amount of fuel is increased. Write to Us About Your Motor Troubles The Popular Science Monthly invites you to send your auto- mobile problems to the Automobile Editor. anything you want to know about a car, and he is here to help you The quick intake and discharge of the gases from the cylinders also permit of greater power through an increase in engine speed. Re-Using Lubricating Oil Q.—Can the lubricating oil used in auto- mobile-engine cylinders be re-used for other purposes on the car, and if so, must it be strained or otherwise treated?—S. W. B., Boston, Mass. A.—Provided the engine lubricating oil is drained from the engine crankcase immediately after the car has run 1000 miles, it may be re-used for lubri- cating the spring-bolts and connections or even in the gearset if it is strained and was a good oil in the beginning. When used for gearset lubricant, it should be mixed with grease until of the consistency of a non-fluid oil. Soapstone in Tire Casings Q.—What is the purpose of powdered soap- stone when sprinkled inside a tire casing ?— A. B., Easton, Pa. A.—Soapstone acts as a lubricant to prevent the tube from sticking to the casing when heated up and to prevent friction between the tube and the casing, the principal cause of rapid tube wear. Soapstone should be renewed He can tell you once or twice a year. Great care should be exercised in sprinkling the soapstone inside the casing in order that it is spread evenly and not in spots where it = heat up and burn the rubber of the tube. To-Day’s Gasoline Q.—What does the gasoline used for cars test per day? Can gasoline fuel be com- pressed and exploded without electrical ig- nition? If gasoline can be compressed to ignite of itself, to what i? must thefuel be compressed ?—F. S. P., Durham, N. H A.—About 54° B. Yes. About 500 lbs. pressure per sq. in. to insure con- tinuous operation of the engine under the most adverse conditions. Delivery Costs and Sales Q.—Please supply us with figures relating to the ratio that cost of delivery should bear to =— gross sales.—E. & B. Mfg. Co., Selma, a. A.—According to the Federal Census Bureau, 1916, the percentage of delivery costs to gross sales are as given below: Business Per Cent Business Per Cent Se See 45.6 Brewetes .....0s00 9.2 Soft Drinks...... Dee SEAPIEE .6 os ics bled 6.8 Brick............19.9 Groceries and Meat.4.4 ee eee 19.8 Hardware .......... 3.0 Laundries........ 15.3 Furnitureand carpets 2.8 Coal and wood...15.2 Department-stores...1.5 Ice-Cream... .. +0. 14.9 Wholesale meats..... 1.1 Dairy Products. ..12.1 78

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August, 1921 A Priming-Cup for the Intake Manifold RIGHT-ANGLED priming-cup set at the fork of the intake manifold on the Ford engine will be found to be one of the most useful fittings on the car. It is seri- ously needed on the Ford, but may be used on many other engines to advantage. If a dash ‘control is added, as shown, its utility is very much increased. The thread is the standard %-in. pipe for which a 5/16-in. drill should be used. These may be obtained in any hardware store or machine-shop. Buy a priming- cup with a flat handle so that a hole may be drilled in it for the rod from the dash. This rod should be bent at right angles and kept from falling out by a split pin. The greatest utility of this fitment is in removing carbon. Water is poured in slowly while the engine is running. The gas lever will have to be advanced slightly, the dis- tance being found by trial. Water admitted by this means turns to steam, blowing the carbon out with the exhaust. Ifthe car is equipped with a muffler cutout, tie this open so that the water and carbon will not accumulate in the muffler. Place a piece of newspaper below the cutout, and you will marvel at the amount of carbon removed. Some use peroxide of hydrogen, on the theory that the extra oxygen combines with the soot, burning to carbon monoxide or dioxide and so assisting the process. A quart of this liquid run through the engine is certainly less expensive than removing the head and scraping by hand, besides taking much less time. On account of its convenience it may be done fre- quently, whereas if the carbon must be removed by hand, there is a tendency to put off the process of scraping until the cylinders are badly choked. Alcohol is favored by other drivers and is to be used in the same way. Use the denatured, as it is cheaper than the wood alcohol. On no account use kerosene for this purpose. Some misguided drivers use it and point to the heavy smoke issuing from the exhaust as evidence of carbon being re- moved. But this smoke will be produced from a perfectly clean engine, as it is merely Sun- and Rain-Shield for the Automobile HE owner of a Ford sedan recently made and attached to the frame about the upper section of the wind-shield of his car a simple sun- and rain-shield, the de- This homemade accessory will keep sun and rain from the face of the driver, increasing the margin of safety tails of which are shown in the illustration. The frame consisted of a length of 44-in. brass rod with four bends, a width of rub- berized fabric, such as is used for top covering, sewed about the frame, and the rear edge seamed. This improvised awning By Robert A. Chandler unburned kerosene. Consider a minute. Your carburetor is still feeding a mixture of gasoline to the engine that is very nearly correct. If kerosene is added, there is not enough oxygen left to absorb or burn all of If your intake manifold is equipped with a priming-cup as !shown here, cleaning out the carbon in the cylinders is greatly facilitated it, so it is charred, making a heavy smoke of unconsumed carbon. But some engines suffer from an in- crusted layer of carbon that cannot be removed: except by scraping. Here again the priming-cup will be of temporary use, for it may serve to diminish the knock. It will not remove the scale, but when the knock develops, a few cupfuls of water will quench the fire and wet the carbon enough to keep it quiet for some time. This enables you to put off the process of scraping until some more convenient op- portunity. Another use for this fitting is to assist in starting the engine, especially in winter or even on a cool morning in summer. Gasoline may be fed while the engine is cranked. The Ford carburetor has a pool of gasoline especially made for aiding in starting, and the choke valve controlled by the wire through the radiator undoubt- was secured by means of four small bent clips with screws to the wood framing. The attachment was made for several purposes—as a protection from rain blurring the upper glass of the wind-shield, to shut off the direct glare of the sun from the eyes of the driver, and to overcome the confusing glare of the overhead street lights when driving at night.—G. A.LUERS. An Emergency Repair of a Clutch-Pedal Stud WAS traveling on my motorcycle through the desert regions of the West when I had a fall that broke the clutch- pedal stud of my machine. At first it seemed a hopeless problem, but I solved it by using a long-shanked anti-theft padlock. CLUTCH LEVER The picture clearly illustrates how the shank was passed through the mo- tor base and the clutch lever, MOTOR BASE FRAME BAR: holdingit in place How the padlock § after the lock had shank was used been snapped. 79 edly assists, but what is needed is a spray of gasoline that will evaporate quickly. As a liquid running down the side of the manifold gives a greater surface than the pool, much better carburetion results. If the valve of the priming-cup is only opened part way, so as to allow the gasoline to enter slowly, and the engine is cranked at the same time, atmospheric pressure will force it in as a spray, making eapentin much more certain. Finally our device may be used to give a little more air to the mixture and so develop more power with greater economy of gasoline. The only adjustment to the Ford carburetor is on the spray nozzle, the air-valve being entirely automatic.and not subject to control. The driver changes the adjustment of the spray nozzle from time to time until he finds the best position for COTTER PIN INTAKE MANIFOLD ) CONTROL ROD PRIMING CUP The detail of the attachment of the priming-cup is here illustrated, also the method of controlling the valve from the dashboard level roads, and then he opens the valve about a quarter turn for hill-climbing. By experimenting with the priming-cup as an auxiliary air-valve, giving more gasoline from the spray nozzle, and chang- ing the air to fit, he will occasionally find a marked improvement. Removing the Ford Wheel Spindle Cone HEN the inside cone of the Ford or any other smaller spindle becomes worn, it is often difficult to remove it from its seat. First a slanting slot is cut with a hacksaw about 14 in. into the spindle body, behind START CONE ! WITH CHISEL AND HAMMER PRY CONE OFF with TIRE IRON 7 UNDERCUT wiTH MACKSAW With a blunt chisel and a tire iron the wheel-spindle cone may be removed the hardened cone, then a chisel is used as a wedge between spindle and cone until the cone becomes loose enough to be removed with two tire irons used as pinch bars.

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A Hinged Support for the Coffee-Mill COFFEE-MILL permanently at- tached to the kitchen wall is apt to be in the way and is also a dust-catcher. An easily made wooden angle-bracket hinged to the edge of a cupboard-door When the coffee-grinder is not needed, it can be swung out of the way under the kitchen cabinet frame permits in its outward position the easy operation of the mill, and when not in use it can be swung into an out-of-the-way position inside the cupboard. The illus- tration shows clearly how the support is constructed.—EVERETT ROGERS. Keep Your Valuables in an Alarm Safety Box Gre box will cause a bell to ring if it is lifted’ from its resting-place. The bottom compartment contains a contact device, electrical bell, and battery. The [ CONTACT at DEVICE UPPER COMPARTMENT BELL ZA Wy F HOLE IN Le BOTTOM OF BATTERY BOX Lifting the treasure-box turns on an electric alarm concealed in the box top compartment is used for the valuables. The details of the spring-contact device are shown in the illustration. When the box is resting on a table, the spring-contact device will be held up. When the box is lifted, it will. go down, - making contact, and ringing the alarm bell. A lock should be placed on the box.—GEORGE BENNER. This Iron-Pipe Gate Will Close Itself [ DESCRIBED here is a gate that can be made from odd pipe parts that would ordinarily go to waste, but even if it is necessary to purchase the parts, the cost will be slight and a neat and efficient self- closing gate will result. It is especially suitable for entrances in offices, machine- shops, and garages. It is made of 5 pieces of 2-in. pipe of suitable length, two 2-in. elbows, and two 2-in. tees, one 2-in. foor flange, one 114-in. floor flange, one 1}4-in. elbow, a 114-in. long nipple, and a 1}%-in. pipe of the proper length. The gate part is made up first. The lower end, B, of the hinge-pipe, A, has an extra long thread and is screwed in as far as possible and then unscrewed into the upper tee where there is a very short thread. About three turns should make this tight. This leaves the lower end somewhat loose but not noticeably. The short piece is cut on an angle of about 30 degrees and one part is screwed into the lower end of the gate tee. The other piece is screwed into the floor flange. The 114-in. pipe is passed down into this pipe and fastened with a small bolt passed through. Slip the gate over the vertical pipe, place the elbow, nipple, and other floor flange, and screw into place on the wall or door frame. Smooth the bearing FLANGE mT | FLANGE This gate, when released after having been opened, will close by its own gravity surfaces of the gate and the support with a file so that they will work easily, allow- ing the gate to drop and swing into the closed position when not in use. A Homemade Holder for Pens and Letters MATERIALS for making this holder are a piece of wood for the base and two more pieces for the letter-holder. One groove is made about 1 in. from the edge of the base, as shown in the illustration. This groove is rounded, so as to hold pens and pencils. Two more grooves, square at the GROOVES q ROUND GROOVE This holder is very useful and, if neatly finished, will be an ornament for your writing-desk bottom, are made in the middle of the base, to hold two upright pieces of wood, be- tween which letters and. papers are put. The picture shows where they are placed. Shape the two boards to act as the letter- | holder to suit your taste and glue or screw them in the two grooves meant for them. Sandpaper the wood and give it a coat of shellac or varnish. ARTHUR GOLDENBAUM. 80 Popular Science Monthly Hold the Faucet Open with a Key-Ring pravcers of the type shown in the accompanying illustration are em- ployed very often in hotels, clubs, lava- tories, restaurants, etc. In this type the inconvenience of having to employ one Did you ever think of using your key- ring for holding the faucet of the wash- . Stand open? Try it! hand to maintain a flow of water is appar- ent. The illustration shows a method of avoiding this handicap by a simple expe- dient, a key-ring, which practically every man carries. Just slip the ring, keys and all, over the widest part of the handle. Your water supply is constant and both hands are free. —ANTHONY E. ZIPPRICH. How to Keep the Pen with the Ink-Bottle FTEN _ the household pen becomes sep- arated from the household _ink- bottle. The lit- tle device shown here will keep the pen where it belongs. A piece of fairly heavy wire is wound around the neck of the ink-bottle. The surplus wire is then bent into a hook that has spring enough to hold the pen. When you have finished writing, the pen is placed in the hook, where it will remain until again needed.—CARL ROYER. Old Rope Can Be Used for a Doormat ore fastened to a board with staples can easily be made into a very ser- viceable doormat. A staple is placed at one end of the rope. The rope is then run across the board and another sta- ple placed. This operation is re- peated until all the available space on the board is used up. About .20 ft. of 1-in. rope make a_ very good doormat. The spacing Attach the pen to the ink-bottle 11% in. between ropes.—L. LAv- Old rope makes an excellent doormat RIER. should be about - of | late pro ang two rap troc par or ¢ stru con dim par cyP The wot pies is t clin ble to ¢ wit fra

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August, 1921 Constructing a Table for Photographers By Ernest Barton N amateur photographer’s greatest help is a table suitable for all kinds of photographic work. It consists of two lateral frames between which the table proper can be inclined at any reasonable angle to facilitate the work. It also carries two sliding tops that enable the photog- rapher to take macrophotos by simply in- troducing bellow extensions. With this ap- paratus life-sized pictures of small animals or objects can also be secured. The first important step in the con- struction of the table is the frame. This consists of two equal lateral sides whose dimension and shape can be seen. The parts are made from 1 in. by 1 in. pieces of cypress, since this is both light and strong. The top frame is made of a wider piece of wood, 34 in. by 134 in. The center of this piece receives a hole 34 in. in diameter. This is the pivot and allows the table to be in- clined at any reasonable angle. When the two frames have been assem- bled, glue them together and allow them to dry. Six cross pieces are made from 1 in. by 1 in. wood, 12 in. long. and provided with dowels. These are attached to the frame as shown in the illustration. To make the sliding table, two pieces of wood 34 in. by 134 in. and 4 ft. long are taken for the sides. Clamp these down upon the table so that they are rigid, and begin to cut two grooves at least *4 in. in depth. If you have no plane for this kind of work, take a chisel 14 in. in width, bore a slanting hole through a piece of wood, provide a slide on one side, and place the chisel in this hole. This is a simple but very effective plane for cutting grooves. When both pieces of wood have been grooved and each piece has received two grooves at equal distance from each other, each piece is screwed to a 1 in. by 1 in. strip, 1 ft. in length. The exact center of each of these pieces is provided with a hole 34 in. in diameter. The pivot consists of a 1 in. by 1 in. strip, 15 in. long; with the exception of 814 in. from the center, the strip is rounded off so that it will fit snugly through the holes provided. Pass this pivot through the table holes, and attach a board to the two lin. by 1 in. in which the holes were made. Also fasten the center of this pivot to the board so that it is immovable. At one end of the table-top attach a 1 in. by 1 in. so that the upper part of the groove is plugged, and at the other end attach an- other so that the lower groove is stopped up. These strips will prevent the sliding table from sliding in the wrong direction After all parts have been cut and ad- justed, it is easy to join them together to form a rigid structure Here the table is tilted for greater con- venience in focusing for the life-size photograph of a plant . For taking greatly enlarged photo- graphs of minute objects an extension consisting of a paper tube is used and will also hold the grooved top firmly together. Place the table-top into the holes of the frame, and place the cross pieces in place, but without permanently fastening them in place. See to it that all parts fit snugly together and that the table can be easily inclined. Then attach two large angle- irons to the board, turn the lower end so that it will face the sides of the frame, and, after finding the arc the angle-iron de- scribes, place the piece of wood to the frame as shown. This keeps the table- top rigid in any position with the aid of winged screws. The sliding frames are now made. These consist of 1 in. by 1 in., having narrow strips attached that fit easily into the grooves of the frame so that it slides smoothly. The tops of the frames receive boards at intervals, which keep them rigid and firmly pressed into the grooves. The upper frame slides to the right, the lower to the left. When all these parts have been assembled, the cross pieces as well as any other loose pieces can be glued and fixed in place. The table-top can be further strengthened by attaching two braces run- ning from the end of tke table to the lower part of the angle-irons. It is desirable to provide a few shelves on the table, not only for convenience, but also for strength. Their place of attach- - ment can easily be seen from the illustration. After staining or painting the table, it only requires the camera. This should be a double-extension bellows camera, and it is to be firmly fastened to the upper mov- able table. For larger extensions, large diameter paper tubes or square tubes made from cigar-box wood are easily con- structed. These should be so made that one box fits snugly into another, and so that any number of them can be used according to the magnification desired. An important detail is to see that each extension finds a support upon the table. This prevents sag and breakage of the different extensions. The greater the magnification, the better the lens should be. Excellent photos can be taken with a double anastigmat lens of wide aperture. And even here it is not recommended to make enlargements more than ten times. For higher magnifications use a microscope that can easily be attached to this table. Without any extra bellows extension photos can be taken in their natural cize. Focusing in any of these cases is done as usual upon the ground glass. To obtain especially sharp negatives, remove the ground glass, and, taking a hand lens and holding it in the plane of the removed ground glass, focus with its aid. To Keep Your Magazines in Order | get essa here is a magazine - rack with forty-two separate compartments. In the case of small magazines, two may be located in one compartment, hence the rack will take care of fifty or more. stacks of papers, booklets, magazines, etc. It is most inexpensive to build when constructed of the lattice material shown. The ccrners and middle supports are 2 in. by 1 in. material; 400 ft. of the lattice meierial was required and 10 ft. of the 2 in. by 1 in. The frame for the rack was first built: It was 18 in. wide, 6 ft. long, and 7 ft. high. It was not secured to the floor and was placed 3 ft. from the nearest wall along its side so that it may be approached from either side. After the frame was made it was simple enough to cut and nail the lattice sticks in place as shown. Small wire brads, made purposely for tacking together light lum- ber, were -used in building the rack. upon 81 the frame. The completed rack was filled and stained light oak. Each compartment has across its top the name of the magazine, catalogue, or paper that it contains. This homemade magazine-rack will hold many magazines or pamphlets and. is easily accessible for cleaning i 2 ; 5

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Popular Science Monthly Coil-Winding Suggestions for the Amateur INDING a coil of insulated wire for an electromagnet, dynamo field, or transformer becomes an easy operation if the amateur follows the directions given below: In Fig. 1 is shown a coil wound upon a round core. To simplify matters, a single layer of wire is shown, but the same prin- ciples would apply to a coil of any number of layers. To secure the beginning, or first turn, of the coil, a short length of tape, or tough paper, if fine wire is used, is doubled over the beginning of the first turn and the succeeding turns wound over the two layers of tape. After winding on four or more turns, the tape ends are brought out and the winding continued. Then if there is any looseness at the end of the wire, this may be taken up by pulling on the ends of the tape. The last turn of the coil is secured in a similar manner; a length of tape is doubled and laid on the core before winding the last four or five turns, these being wound over the tape, leaving a loop at the outer end through which the end of the wire is threaded at the last turn. Then the loop is pulled tight and both ends of the coil are held in place. Sometimes it is desired to connect less than the whole number of turns of the coil into the circuit, as in the case of a trans- former or reactance coil. Then attach ex- tra terminal wires, or ‘‘taps,” at the points covering the required number of turns. The simplest way to make a tap is to solder a strip of copper to the wire, before winding it in place, by removing the insu- lation from a space equal to the width of the strip, bending this around the wire and soldering. The strip is then insulated by wrapping with oiled paper or empire cloth and it may either be brought out through the coil at right angles to the core, between the subsequent layers, or laid flat and PUSH WIRE THROUGH ND TIGHTEN ° |/PAPER a .. | (a | INSULATION \/COPPER STRIP / SOLDERED 10 7 WIRE AS TAP mae How to begin the winding of a wire coil around a cylindrical core and how to fasten the end coils brought out through the end of the coil, between two adjacent layers and parallel to the core. The next point to be taken up will be the disposal of the troublesome inside end of the coil and the best way will be to do away with it altogether and have both ter- minals on the outside of the coil. This can be accomplished by winding the coil in two sections, as in Figs. 3 and 4. First a short strip of brass or copper is cemented to the core insulation midpoint of the winding space and the inside ends of both sections will be soldered to this strip. A spacing block is made to clamp over half of the winding space while one section is wound, first soldering the end to the strip and insulating it from the first layer with paper or tape. If the section is evenly and tightly wound, it will remain in place after the spacing collar is removed. The beginning of the second section is By H. H. Parker SOLDER TO INSIDE END OF BINDING OTHER SECTION BEGINNING OF FIRST ONE SECTION FORM | FLEXIBLE LEAD {¥ SECTION SOLDERED F1G.4 WOUND AND BOUND \SOLDERED TO TO BRASS STRIP TEMPORARILY WITH END OF MAGNET FIG3 CORD FIGS WIRE BEFORE END FLANGE APPLYING TAPE Winding a coil in two sections is here illustrated. The sections should be wound in opposite directions now soldered to the other end of the strip and the section wound in the opposite direction from the first. It is absolutely necessary to reverse the direction of wind- ing, as otherwise the two sections will neutralize each other. If the winding is performed in the lathe and it has no re- verse, the same result is attained by remov- ing the coil and turning it end for end after completing the- first section. As shown in Fig. 4, both ends cf the completed coil will lie on the outside, and if one should break, INSULATE SOLDERED JOINT BEFORE After the coil is completed, it should be wound with insulating tape, which will hold the coil firmly together it will be unnecessary to re-wind the whole coil. Furthermore, there will be no inside terminal to lie across the end turns and both ends will lie away from the iron core. A form wound coil may be constructed in the same way and taped after removal from the form, but a modification is shown in Fig. 5, where two form wound sections are made separately, both wound alike and in the same direction. Then one is turned end to end, the now adjoining inside ter- minals soldered together, the joint insu- lated and the two sections taped into one coil. Fig. 6 illustrates the proper way to apply the tape. First, terminals of lamp cord, or other flexible conductor, are soldered to the coil ends to serve as leads and prevent breakage. As it is usually preferable to have both terminals leave the coil in the same direction, one lead is reversed as shown. The tape is started under and away from the terminal con- nections, which should both be insulated after soldering, carried around the coil and ended over the leads and a little beyond the beginning of the wrappings. Figure 8 shows how a completed form wound coil may be opened up slightly by means of a smooth greased wooden wedge. In Fig. 9 a speed indicator is attached to ———» SLOT FOR BINDINGS For ascertaining the number of wind- ings on the spool or core a speed indi- cator may be used $2 the end of the winding rig shaft (or to the lathe spindle) to keep track of the number of turns, something the coil winder himself will find it difficult to do. Should it be necessary to unwind a number of turns, the revolution counter will back up also, so that the correct count will not be inter- fered with. Before the winding is started, a layer of heavy cord is wound on the core of the form; the insulation, if used, is wound over this. When the coil is com- plete and the flange removed from the form, this cord layer is pulled off and the coil then easily removed. Slots are shown in the end flanges of the form through which bindings are placed to temporarily hold the coil together after removal. Figure 10 shows how brass or iron strips are used to hold together the two end flanges of a coil that is wound directly on the core. If the core is round, three or four narrower strips are used. The Camera Romantic for Home Use HE camera romantic, as its name would imply, has no practical value, but is interesting and amusing, as with it you can get all kinds of effects. To make one, get two small mirrors of the same size, about 314 by 5% in. Take off the backs or frames, and in the center of one scratch a 4-in. hole in the silvering. Now make a little box with ends of the same size as the mirrors, and nearly twice as long, with no top to it. Cigar-box wood will answer the purpose. At one end This toy, primarily intended for chil- dren, will also entertain grown-up persons bore a hole so that it will exactly fit the hole in the silvering when the glasses are placed in the box at the ends. Now make some scenery, such as little trees, houses, and such like, to stand at the sides of the box. Paint them on thin card- board on both sides and cut them out so that one edge is the natural shape and the other straight, set them on pieces of wood and stand them against the inside of the box. Make little figures of persons and animals to stand about in the center; paint them on both sides. Now look through the hole and you will see not only the scene you have set up, but many others. You can make various sets to go inside and have your figures move about by means of wires from holes through the sides or wires from the top. oa 3D he — ~All

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August, 1921 WARFED fruit-trees are always grafted on slow-growing root stocks. They should never be planted so low in the soil that they touch, or cover, the grafting scar. If they are planted too low, they will detach themselves from the root- stock, produce their own roots, and soon lose the entire appearance of a dwarfed fruit-tree. Then they produce many strong shoots, and flower much later than before. The grafting scar is always characterized by a peculiar thickening of the stem and is always found about )4 in. above the root-stock. The best-developed fruit is always pro- duced by the dwarfed trees. Where a common apple-tree produces ten apples, the dwarfed tree produces but one, but this one fruit is of the best quality and superior to ten apples of the common tree. For their size the tiny trees produce a greater quantity of fruit than the larger trees. In addition to this, these trees produce fruit in the second year after transplanting, and sometimes even after the first year. There are two classes of dwarfed fruit- trees: those that are free standing, and those grown against walls or lattices. One of the free-standing forms is. the pyramid. It consists of a single vertical stem from which side arms are produced. They girdle the stem uniformly of their own accord. It should always be observed, when pruning, that the branches are cut just above the buds, and that the buds are op- posite to the main branch. The main ov’ of branches can be formed, leaving the main stem vertical. Trees That Cannot Be Forced Fruits containing large stone pits can not be grown in pyramid form. Dwarfed trees that are to be grown against walls or are to be forced into definite shapes, require permanent sup- ports. The apple does not like to be placed against the wall; it develops better and more luxuriantly when it is placed in the open where it can receive light and air >. from all sides. 5 All latticed and formed fruit-trees are the result of constraint. All of our fruit- trees attempt and desire to grow upward, mA Owe we VM One of the most attractive forms of training dwarfed fruit-trees is the free- standing double-U. shown here branch should be so cut that. a new series | By E. Bade The beginnings of a simple U-shaped tree require much care and attention How the young tree is trained to form a cordon along the stretched wire away from the soil and toward the light. But in these dwarfed trees the upward growth is checked by the fruit-grower to make the trees conform to the desired shape. They are not meant for the orchard of the amateur who can not devote his entire time to the care and pruning of these trees. Only the simplest forms are recommended and the larger trees should not be chosen for training. The three main forms of the trained fruit-trees are the cordon, the -palmette, and the free standing form. ' All are developed from one-year-old grafted stocks that, through pruning, were forced to grow in the desired form. The cordons are vertical or horizontal one- or two-armed trees. They have one main stem, about a foot above the ground, and one or two branches, which, when they are trained horizontally, are attached to wires strung at the right height. Those forms having two arms should have both at the same height. But this is not accom- plished by pruning the one-year-old stock, since one branch will remain lower than the other and also be weaker. Both branches must be developed from the main trunk. If both branches should not be equally strong, then the stronger can be bent slightly downward in the spring and the weaker bent slightly upward. Since the sap prefers to rise as perpendicularly as 83 Suggestions for Training Dwarfed Fruit-Trees possible, the weaker branch will soon be- come stronger, and when both are equally strong they can be replaced in the original positicn. Cordons grown at an angle are usually placed against lattices. They are trained to grow at an angle of 45 degrees or less. The trees are planted two feet apart. The same is done with the double cordon, but in that case their branches cross each other. The simple vertical cordon is especially adapted for narrow high lattices and the pears are the best adapted for this form. They are easy to train and to keep in good condition. Some of the Forms that Are Used The U form and the candelabrum form are sometimes considered as a double or triple cordon, but are more correctly de- fined as a variety of the Verrier palmette. These forms have a number of branches arising from the main stem and running, one on each side, in opposite directions. The U form has only two branches which, after branching from the main trunk, are perpendicular. The candelabrum has a third branch arising from the main trunk, but this branch only too often escapes the hand of the pruner and does not bear any fruit. For this reason it can not be recom- mended. A much better form is the Verrier pai- mette, which often covers an entire lattice. The distribution of the sap is one of its best features, and it is even and uniform in shape. It can be successfully used with any fruit-tree as its shape is most constant. But one should only plant Verrier pal- mettes with an even number of branches. A well-formed Verrier palmette is the four-armed or double U-shaped tree. It is easy to keep uniform, the strength of the opposite arms are equal, and the fruiting branches are well distributed. These are also developed from one-year-old grafted stock cut back so that three buds can develop. The upper of these three buds lies forward; the other two must lie side- wise and opposite each other. These buds form the main stem and the two lateral branches. All other shoots that may develop are pruned and cut off. The shoots of the three buds are attached to a support. The center shoot is trained ver- tically, the two lateral branches are trained at an angle of about 45 degrees. Later, before they become too woody and hard, they are placed in a horizontal position. In this picture is shown a beautiful example of a fruit-tree tramed in pyramid form like a candelabrum i 4 eg i bs

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To Make ( WOOD PLUG iyi) Ls METAL COVERING z SPRING METAL LONG METAL STRIP One of the simplest switches is the plug-switch, which is here shown singly and for four contacts 7? is the purpose of this article to outline the construction of a number of simple switches and connecting devices that will facilitate experimental work along electrical lines. Any one of the switches described can be put together with materials at hand. A simple little jack or plug switch is shown in Fig. 1. It is necessary to have only a small base and a little block of wood and two pieces of springy metal, such as phosphor bronze, to construct this switch. The block is mounted at one side of the base and a piece of phosphor bronze bent at right angles is drilled out to receive two screws. This is screwed to the block as illustrated. Another piece of phosphor bronze, bent in the form of a hook, is screwed to the base opposite the block as shown. This spring should be bent so that it will not touch the block. The little wooden plug is cut from a piece of soft pine and a metal piece is tacked over its end. Thus, when the plug is inserted between the two metal pieces of the switch, the circuit will be closed, and when the plug is removed, the circuit will be opened. The switch in Fig. 2 is for use with four circuits. It will be seen that here four blocks are used similar to the single block used in the switch shown in Fig. 1. In- stead of four individual contacts a long strip of metal may be placed to act as a contact for the four blocks. A method of converting an ordinary double-pole double-throw switch into a reversing switch is shown in Fig. 3. Here + An ordinary doub!e-pole double-throw switch can be converted into a revers- ing switch two flexible contacts connect the four end points of the switch in the manner shown. The connecting wires should be insulated where they cross. This switch will find a number of uses in direct-current work where it is necessary to reverse the current to reverse the polarity or direction of a motor. Another useful little switch is pictured in Fig. 4. First a base is squared up and sandpapered. Then a littie wooden block with steps cut in it is mounted on the base. Three phosphor-bronze strips are then cut and drilled at each end. It will be seen that these strips are of different lengths to correspond with the steps cut in the block. One end of each of the strips is provided By L. A. Laurier with a contact and the other end is screwed down to the corresponding step in the block. The top piece has an insulated knob at its top. Three binding-posts are mounted on the base. This little switch will find a number of uses where three different circuits are to be closed simul- taneously. An ordinary little single-circuit switch that can be put together in about fifteen minutes is illustrated in Fig. 5. Two springy brass strips are cut the same length. These should be about 4 in. wide. They are drilled out at each end to receive an 8/32 battery screw. They are fastened to the base with binding-posts. The free end of the lower spring is held in place with an 8/32 machine screw that also acts as a contact point. The upper contact. piece carries a rubber knob similar to those em- ployed on telegraph keys. A very clever little reversing switch for use with voltage up to 110 and that will allow 5 am. to pass is shown in Fig. 6, A and B. A square base is cut out of oak. Six holes for binding-posts are drilled in this as shown. It will be necessary to countersink these holes underneath so that BINDING; RUBBER HOLES FILLED POST KNOB) CONNECTORS. _, WITH MERCURY © S FIG.S \\SPRING BRASS WOOD HANDLE Here are several different forms of simple switches, which are all useful in the laboratory the heads of the screws will be flush with the surface. Six more holes are drilled halfway through with a \%-in. bit. The worker must take care to go only halfway - two brass ends are fastened to it. Popular Science Monthly Various Kinds of Electrical Switches through, as these holes are to form cup: in which mercury is placed. The four corner holes are connected in the manner shown. This can be done with two insu- lated pieces of wire. Of course the insula- tion must be cut off. where the ends of the wire dip into the mercury. A few small staples may be used to hold these connect- ors in place. The handle for the switch is shown at B. The center portion of this is of wood and. Three holes are drilled in each one of these end pieces to accommodate the corresponding number of heavy copper wires bent in the shape shown. In bending these wires care must be taken that they are placed the proper dis- tance apart as the end of each wire must dip into one of the mercury cups. The center wire should be a little longer than the other two so that when the switch is placed on one side it will rest there until it is pushed over to the other side. The two center pieces of wire go into the center mer- cury cups. The wires should be soldered in the metal ends of the handle. Only enough mercury is placed in the cups to make good contact. When the switch is not in use, the mer- cury can be run off into a little bottle. It should not be left exposed, as mercury fumes are poisonous. A simple little connector that will find a multitude of uses in electrical experiments is illustrated in Fig. 7. This is made by cutting off a piece of 1l-in. brass stock. Four holes are drilled as shown. Four more holes drilled in from the periphery to the four holes first made are tapped out with an §/32 tap. A No. 29 drill should be used. Four brass 8/32 machine screws are then placed into these holes. This little con- necting-plate will be found very useful in wireless experiments. Figure 8 shows another connector made from a solid piece of brass stock. The center of this is drilled out and two holes to accommodate 8/32 brass screws are placed in each end. A very good electrical connection can be made with this, Electric Motor for Sewing-Machines IMPLE but efficient is this method of attaching a motor to a sewing-machine. A small electric motor of sufficient power to operate the machine is necessary. A wooden block support is placed back of the balance wheel and screwed to the machine top from beneath. The motor is bolted to a piece of board for a base that is fastened to the support with a brass butt hinge as shown. A stop is placed directly under the motor. A strong coil tension spring is fastened to the motor base and the machine top to hold the motor in place and .orm the tension to keep the drive-belt tight. The drive-belt should be made so that it is at driving tension when the motor is down in position for operation. A light wooden rod is fastened to the rear of the pedal and hinged to the back of the motor base as shown in detail. A small brake of wood is then made and screwed to the front. of the motor base, but its posi- tion can be found only by experiment. Wire the motor with flexible lamp-cord and place a small snap switch on the machine top in a convenient place. To operate, it is only necessary to press 84 down on the foot pedal and turn on the switch and when the motor is running to speed, gradually release the pressure on the pedal and the motor will drop back and take up the slack in the belt, thus starting the machine. To stop the machine, press on the pedal; that will raise the motor, loosen the belt, and apply the brake. SAME RADIUS AS BALANCE-WHEEL -= --- Pressing down the pedal stops the sewing-machine by causing a slack in the belt and pressure of the brake

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August, 1921 Protect Your House with an Automatic Fire-Alarm HE auto- matic fire- alarm here de- scribed is sim- ple and inex- pensive and can be made by any one with a saw and a few drills. The perspec- tive drawing will show the general con- struction and assembly. A light L-shaped wooden frame, screwed fast to a supporting back of the same material, carries on a pivot at O the twisted copper strip C, which is in electrical contact with one side of a circuit entering at X. The other side of the circuit enters at Y, ter- minating in the screw S, while a stout spiral spring P is so fastened to the bar C as to continuously tend to complete the cir- cuit by pulling bar C down against screw S. The circuit, however, is normally held open by a column consisting of two pointed pencils made of Wood’s alloy, shaped like short wire nails, the heads of which rest on each other as shown at H. When the column is placed in position as in the picture, the circuit can only be closed if the column collapses. This alloy melts at 163° F., and just as soon as the column softens enough to show a slight curvature, a state of inability results that causes the two halves to fly out sidewise, due to the force of the spring, and allows the bar C to be pulled down smartly upon the screwpoint S, thus making a very positive completion of the electric circuit. The wooden casing enclosing the device should be painted or stained to match the woodwork of the room and should be placed at or near the ceiling of the room. Several instruments may be electrically connected in a variety of ways as follows: 1. A battery and bell may be attached to each instrument. 2. A central bell and battery may be bridged by any number of instruments. 3. A central annunciator and battery may have separate lines wired down from each instrument. 4. The last two methods may be com- bined. Method 1 is adapted only to special cases and may be passed over as not of general use. Method 2 will be found best suited to a majority of cases. The central bell and battery should be placed, say, in the bed- room and from it a single pair of wires will be led successively past each instrument in this and the other rooms, the terminals of the instruments being connected directly across the wires. In many cases the exist- ing doorbell with its battery may be pressed into service as a fire-alarm by connecting the fire-alarm circuit to the a= FIG.2. O The trigger part of the fire-alarm BELL DRY BATTERY y TODOOR In this diagram four instruments are shown connected with the same bell and battery bell and battery (or transformer), as shown in Fig. 2. This diagram illustrates the wiring of method 2, whether or not there is a doorbell circuit operated from the same battery. The instruments in the different rooms are designated by the numbers 1, 2, 3, 4, etc. This method is open to the objection that it would afford no clue to the exact location of the fire. In a dwelling, this would not be a serious matter, but if the premises are extensive, as on a farm with numerous buildings, in addition to the dwelling, a more definite means of locating the fire would he desir- able. This can be obtained by using method 8, a diagram of which follows (Fig. 3). The annunciator is merely a terminal box on which are mounted little pointers actu- ated by magnets connected in the individ- ual circuits so that should the instrument on one circuit close, the pointer would im- mediately fly up and point to the number corresponding to that circuit, at the same time that the bell would ring. (In the dia- gram No. 8 is shown in action.) Thus the location of the fire is seen at a glance. It is obvious that this method is more ex- pensive than Method 2 and a combination of the two methods may often be used to ad- vantage. For example, a man might have ANNUNCIATOR 5a oS Itt FIG.3 Here the signal from each instrument is recorded on the corresponding annunciator dial two instruments in his garage, on one cir- cuit, four in his barn on another, and eight in his house on a third, all three circuits being brought. separately to an annun- ciator. Then should the bell ring and the annunciator point to No. 2, he would know that the trouble was in his barn, though he could not tell which of the four instruments installed there was turning in the alarm.—HENRY A. GERMAIN. Coloring Makes Stereoscopic Pictures More Attractive PHOTOGRAPHIC stereoscopic pictures become monotonous and dull after a while. The uniform shading, the monotone of gray with its few spots of black and white soon tire the observer. The pleasure that can be derived from a stereoscope is greatly enhanced when the photographs are colored. Many colored stereoscopic pictures are sold, but only a few of them stand out in relief. It is comparatively simple to color photographic stereoscopic pictures. Either one of the two pictures can be used and when properly colored with transparent water-colors, the effect, when seen through the stereoscope, is as if both pictures were colored. It is not advisable to color both of the pictures, since it is almost impossible to get both exactly alike, and as the effect is the same when only one is colored, it would be a.waste of time and energy to. tint them both.—E. BADE. 85 ‘When Reaming Is Done with Undersize Reamers HEN rebushing connecting-rods in the steering-gear, or spring shackles, it is frequently found that available reamers are either too large or too small. It is frequently suggested that pieces of tin ve placed at the side of the reamer; but those who have tried this method will agree it is difficult to obtain satisfactory results. A method that serves to make a small reamer cut larger is to insert a small twist- drill in the flutes at one side of the reamer. The drills, being of hardened steel, will hold the reamer to the desired size and TWIST DRILL INSERTED IN FLUTE OF REAMER Here is a trick worth knowing when you have to work with an. undersize reamer stay in the groove without sliding around. Drills graduated for size are usually ob- tainable in every tool-shop and their use with the reamer is very satisfactory. This Toy Airplane Will Shoot Out of Its Hangar HE machine which is constructed after the monoplane type has a single rib for the fuselage. A little wire frame holds the wheels and a skidder is arranged on the tail. The rib of the airplane comes in con- tact with a little brass plate at the back of TIN PLATE Press the trigger and the airplane will shoot out of its hangar Pe ee x ee = aia SH Sa as = 4 GUIDE RODS nu # the hangar. This plate is mounted on two rods held in place by two nuts. Two springs, one on each of the rods, are placed back of the brass plate. These springs are of the expansion variety. Attached to the center of the brass plate and extending through the back of the hangar is a small lever with a notch in it. When this lever is pulled back it pulls the plate with it and the notch holds the plate in position. The airplane is now run in so that its tail will come in contact with the plate. If the lever is lifted, the springs will shoot the plate forward, forcing the airplane out of the hangar door at great speed. If the -wings are properly adjusted, it can be made to loop the loop.—CARL ROYER.

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Foiling the Burglar with a Piece of Wire HEN lock- ing their doors, most per- sons think it sufficient precau- tion to leave the key in the lock to prevent the lock being pick- ed or another key from being fitted from the outside. | While this practice might foil the amateur house- breaker, it is of great assistance to the profes- sional in gaining entrance. All well-equipped burglars carry an instrument resembling a slender pair of hollow-nosed pliers with which they can grasp the shank of the key and unlock the door as easily as if the key had been left on the outside. To prevent this, bend a piece of heavy. wire, like the.solid portion of a sash-curtain rod in U shape to fit over the door-handle, making one leg longer than the other, the longest leg extending 1 in. or more below the keyhole. Turn the key in the locked position as far as it will go and slip the wire through the key-handle, the other end passing over the door-handle. After this has been done, the key cannot be turned or pushed out from the outside and the lock cannot be picked.—H. C. ROWELL.

Travelers will find this device a great protection How to Make a Daniell Cell from Simple Materials MATEUR electricians know that a Daniell cell is best on closed-circuit work. It does not polarize rapidly and is therefore well suited to the needs of the amateur electrician’s laboratory. A few cells will produce sufficient current to operate small motors, bells, etc. The materials entering into the con- struction of the cell are not costly. First obtain a few of the old type glass photo- graphic developing-trays, which may be purchased for a few cents apiece. If these cannot be obtained, any good flat recep- tacle about 2 in. deep and 8 in. square will do. The general plan of construction will be evident upon referring to the illustration. A piece of sheet copper is placed on the bottom of the container. This copper can be obtained at any hardware store. Noth- LEVEL OF ELECTROLYTE ba ZINC PLATE mh f == W

= oe er Ss — — — — ns Ady SENSIS See ae, GLASS \ KNOB COPPER ~ COPPER TRAY INSULATOR SULPHATE PLATE Here is a Daniell cell of the low-dish type, but any other form will serve

ing but copper can be used for this element. Four ‘small knob insulators, such as those used between floors by electricians, are used in separating the zinc plate from the cop- per plate. One of these is placed in each

corner of the tray. The sheet zinc should be about 1/16 in. in thickness. This may also be purchased in any hardware store. About 1% lb. of copper sulphate crystals (commonly called blue vitriol) is placed over the copper plate and the bottom of the cell. Water is now poured in to within 1% in. of the top. The cell is placed on short circuit for three or four hours. In placing it on short circuit it is necessary merely to connect the copper and zinc plates together by two wires. These wires should be soldered to the respective plates. The voltage of the Daniell cell is 1.07 and of course this potential is produced regardless of the size of the area of the plates. The current strength will depend upon the area of the plates and the distance they are apart.—W. H. HOSCHKE. Artistic Book-Ends of Sheet Metal b vied can make a very artistic and prac- tical set of book-ends from two pieces of sheet metal, 4 in. by 10 in., either brass or iron, rigid enough not to bend easily. While the metal is still flat, some design can be cut and filed out at one end. The steel points of an ordinary compass will trace the lines sufficiently clear for cutting. The design shown in the illustration is

- 4" — "| ae g a < SS | . & ae ie ASS @ |z s OF SSS NS g a7 n S17 "RUBBER FROM Fs ' OLD INNER TUBE & GLUED TO BOTTOM. —_ ws w = 2)

These book-ends are practical and may also he made ornamental practically all drawn with the compass and is not difficult to make. After the design has been cut out of the two sheets of metal, bend each piece in the middle to aright angle. A little care should be taken to see that the bend is straight and squarely done. A thin flat piece of rubber from an old inner tubing can be glued to the under side of the book-end to prevent slipping and also any marring or scratching. If made of brass, it will polish nicely and if made of sheet iron, it can be gilded or bronzed or tinted as the fancy dic- tates.—M. J. MUNSON. 86 Popular Science Monthly A Blue-Print Machine from an Old Bottle Spent badly in need of a blue-print frame and having none at hand, the writer set his mind to work to devise a substitute. The idea of using a large glass bottle flashed into mind and it was found to be very WiDE-NEcKED «Successful. BOTTLE. An electric light is placed in the

2 PIKES center. The » SRR 3) evecteic mouth of the bot- LIGHT tleshould be large | i enough to accom- th. modate a 40-watt Banp lamp. One of the large bottles in which malted milk JOLUE-PRINT is sold should be PAPER AND . TRACING used. The tracing and the blue-print If the light isinthe are placed togeth- center, all partsare er and wrapped illuminated tightly around the bottle. Several elastic bands are used to hold them in place. When this is done the light is turned on and the blue-print is exposed.— JOSEPH B. MORAN. | nn 7 | RUBBER Ht | ‘| NN dal

\ ! _ ul How a Simple Snap-Hook Was Evolved HOULD you be short of a snap-hook, here is a quick method of manufactur- ing one: Take a cotter-pin large enough for the purpose and cut off one tine about halfway down its length. The ends of each tine should then be beveled so that when the long one is bent around to meet the short one, as shown, the beveled ends will be in con- tact. If the snap- ¥§ hook is’ then ; I | CU1 OFF ! HERE 1 hardened to gain |} | 1 na more springi- ness, it will be 4 found very ser- u viceable.—L. B. ROBBINS. BEND LONG END UP

Make a snap-hook out of a cotter-pin To Insert Several Carbon Copies in Typewriter "fad you have to use carbon sheets for printing more than one copy on the typewriter, it is troublesome to get them in the typewriter. You can save time and trouble if you will take one sheet of paper, double it; put it over the ends of the paper that is to go in the type- writer, as shown. You will find that you have no trouble getting it started in. Run it through far enough to remove the doubled sheet. —D. S. WRIGHT. PAPER AND CARBON SHEETS

FOLDED SHEET A little trick well worth knowing

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August, 1921 Sawdust Is a Good Cleanser of Oily Hands N machine-shops and factories where the machinery requires constant lubrica- tion, the hands of the workmen often be- come coated with oil or grease. In many establishments the men use rags and gaso- line or benzine for cleaning their hands. But oil-soaked rags and gasoline are highly inflammable and constitute a serious fire hazard. A manufacturing concern in Ohio has solved the problem by providing large cans filled with sawdust in the different parts of Oily or greasy hands may be cleansed with dry sawdust, which soaks in the oil and scours the skin remove the oil from his hands, takes a handful of sawdust from the nearest can and thoroughly rubs and scours his hands with it. The sawdust soaks in the oil and gives enough friction to cleanse the skin without injuring it. The sawdust so used is collected and may be used to soak up any oil that may have been spilled on the floor. Use This Book-Rest with a Lamp Attachment ERE is a book-rest that will hold the book in the desired position and that will at the same time provide you with sufficient light to read the book without undue strain on the eyes. It is constructed with 14-in: boards, as shown here. A piece of brass is bent into WIRE TO BATTERY DOORZ BACK VIEW SIDE VIEW Eye-strain from reading at night may be avoided by the use of this book- rest and shaded lamp the shape indicated, a small reflector is soldered on, and a small hole made for the socket. This, in turn, is screwed to the book-rest. A switch is provided at the right side of the book-rest. A door is made large enough so that the battery can be put in or re- moved when dead. A strip of felt can be the factory...The -workman who wishes‘ts-|-°~ Will you be the NEXT man to learn that Shav- ing with an Enders is— ‘Just like wiping your tace with a towel” ya SAFETY RAZOR ENDERS SALES COMPANY 105-111 West 40th Street New York ENDERS SELLS FOR $1.00 with six blades of the best quality Swedish-base steel. Packed in black Keratol box, velvet lined. Extra blades, package of 5—35 cents. IN CANADA—Razor, $1.50; blades, 50c. FOR SALE BY BEST DEALERS EVERYWHERE Blades—Hand-stropped and Hand-tested glued to the under side of the book-rest if desired.— WILLIAM E. KING. { rt i i if P,

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eee i . LIGHT WEIGHT CAST IRON PISTON a es The Succeesful Light Weight Pistor © PATENTED U.S.A. FOREIGN PATENTS PENDING 2 Do You Own a Car? DELUXE licht weight, cast iron pistons will increase the power, speed and flexibility of any motor and at the same time use less gasoline and oil. They also reduce repair bills by eliminating vibration. Thousands of motorists in every part of the world are proving this every day. DELUXE PISTONS ARE 40 TO 50% LIGHTER THAN STOCK FACTORY CAST IRON PISTONS The weight is saved and strength gained by their patented scientific reinforced construction. Note the rein- forcing ribs under the head and down the skirt. These reinforcements give the piston much greater strength. The reinforcing ribs also serve to carry off heat, insuring a cooler running motor. The DELUXE piston has much less expansion than either aluminum or heavy cast iron pistons. They can be fitted close. Write for booklet giving full information. Supplied standard or over-size for more than 800 makes of automobiles, trucks, tractors, airplanes, motorcycles and marine engines. Patented and Manufactured by CLARK-TURNER PISTON CO. Station C Los Angeles, Calif. For Sale by All Good Dealers and Repair Men. NAVARRE— | Quality Binocular— | Special Price, $37.50 | ERE is your opportunity to get a high grade binocular at a low price. | Standard 6 power 30 m/m—specifications | adopted by all armies in World War as | most efficient under all conditions. Ad- justs to strength of each eye. Extremely | light. Made by master craftsmen. Beau- | | tiful satin finish; heavy leather, velvet- | | lined case; will attract attention any- | | where. Genuine GRAF LENSES. Con- | structed of brass—no clouding of lenses | as is the case with ordinary aluminum- | frame instruments. War contract cancel- | lation price—$37.50—including war tax. | Sent C.O. D. or upon receipt of money | order for 3 days trial. Money immedi- |. ately refunded if you are not entirely satisfied. For further particulars write to | THE NAVARRE COMPANY | | | 707 J. M. S. Bldg., | South Bend, Ind. | | BLANK CARTRIDGE PISTOL - PRICES Blank JOHNSON SMITH & CO., Box 782, Dept. 614, Chicago New Uses for Electricity Have you found a new way of making the electric current work for you? Have you made a new labor-saving or money-saving machine or device that is electrically oper- ated? The Popular Science Monthly will pay $90 in prizes for the best answers LECTRICITY is one of our most useful servants. An outline of its more common daily uses would fill a book of no mean size. The editors of the Popular Science Monthly want to find some uncommon uses for electricity. They want to know what new uses readers of the magazine have found for it in home, shop, or office. The new machine or device does not need to be motor driven, although there is no objection to a motor-driven machine, provided it is new and useful. It must, however, be a homemade device. Electric magnets, solenoids, or heaters may be employed. The Popular Science Monthly offers three prizes for the best answers—a first prize of $50, a second of $25, and a third of $15. the rules outlined below. These will be awarded in accordance with Rules Governing the Contest (1) Contestants are not limited to the number of ideas, but only one method can possibly win the first prize, only one the second, and only one the third. The con- test is open to everybody. (2) The use of the new electrical appliance must be shown clearly, either in a photograph or in a drawing. If a drawing is sent in, it need not be made by a skilled draftsman. It is sufficient that it should be intelligible. While pen- cil sketches will be considered, contestants are requested to make their drawings in ink on heavy white paper. The views should be sufficient in number to set forth the writer’s idea very clearly. The con- testant’s name and address should appear on each sheet of drawings. (3) The drawings or photo- graphs must be accompanied by a description, preferably type- written, in which the method is clearly given. It must be written on one side of the paper only, and it should not be more than 500 words in length. The name and address of the contestant should appear in the upper left-hand corner of the first sheet of the written description. (4) The drawings and descrip- tion entered by contestants must be received by the Popular Science Monthly not later than 5 p. m., on Oct. 20, 1921. (5) The judges of the contest will be the editors of the Popular * Science Monthly. 88 (6) The first prize of $50 will be awarded to the contestant who, in the opinion of the judges, has suggested the best idea of a new use for electricity. The second prize of $25 will be paid to the contestant who sub- mits an idea next in merit. The third prize of $15 will be paid to the contestant who sub- mits an idea third in merit. (7) The winners of the contest will be announced in the earliest possible issue of the Popular Science Monthly. A description of the ideas that win the three prizes offered will duly appear in the pages of the Popular Science Monthly, together with the names of the winners. (8) The editors of the Popular Science Monthly shall have the right to publish meritorious manu- scripts that do not win a prize. The regular space rates will be paid to the contestants who sub- mit the manuscripts thus selected. (9) When a contestant submits more than one idea, the descrip- tion and drawing by which each is set forth must be sent as a sep- arate unit. (10) Manuscripts or drawings — will be returned to contestants if stamps are enclosed. (11) Send drawings and specifi- cations to the Editor of the New Uses for Electricity Contest, Pop- ular Science Monthly, 225 West 39th Street, New York City. Popular Science Monthly

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August, 1921 An Extra Hook for the Telephone Receiver We" a person is called to the tele- phone the receiver is often left dangling at the end of its cord. A little device that will eliminate this incon- venience is illustrated herewith. It is an HEAVY SHEET RASS = RIVET CPS ET 6erew HOLES Do not let the receiver of your tele- phone dangle from the wires. Provide a hook for it extra hook made of stout sheet brass. It will be necessary to cut two strips of brass and rivet them together as shown. Making Good Use of Old Phonograph Records c pnnenet apd phonograph records are usually consigned to the ashcan. Here is a use for records bearing heavy scratches. Of two of them and a cylindrical piece of wood, a splendid spool for wire or cord may be made. The wood cylinder has a hole through it and a_ small machine screw is passed through this. Nuts hold the pieces together. Use large wash- ers under the head of the bolt and under the nut. The little ten- cent records make This spool was very good small made with two old spools. — JOSEPH records B. MORAN. wooD BOLT ANO ) OLD PHONOGRAPH RECCRDS wT Model Your Own Stoppers from Paper [UBABLE stoppers of almost any size may be made from paper. Take a sheet of glazed paper and cut out a circle as shown. The size of the finished stopper will de- pend on the di- ameter of the circle; the length of the stopper will be equal to the width of the paper ring. Now cut through oneedge, and roll the Roll «S paper tightly as : shown, applying a little paste in so doing. Allow the paste to dry and dip the stop- per in paraffin to Paper stoppers may make it water- be made in this proof. manner PAPER RING CUT HERE Au~apal 2t0@7 ge i oked = = TRUNK LINES OF THE BELL TELEPHONE Srey : Senate over 7 70,000 Cities owns and Rural Communi: Ues . Miles of Railway Ose. Passengers Carried «.....+.+00eeee-es0e So BELL SYSTEM Telephones owned and oftiand 12,600,000 Miles of wire owne “ 25,400,000 Number of Employees..... she ,000 Stockholders.........2.0+++ “ 000 Telephone Messages «-++++++.+++000- 000 Uniting a Nation Within reach of the call of your telephone are more other telephones than may be found in all the other countries of the. world. This is made possible by the Bell System of telephone com- munication. The central administration of the Bell System by the American Telephone and Telegraph Com- pany— Provides for invention and scientific research. Provides for the economic manufacture of equipment. Provides for the standardiza- tion of methods. Plans for future extensions. Insures financial stability. It is the complete cooperation between the central administra- tion and the many operating com- panies that produces nation-wide telephone service. It would be impossible for un- related organizations to provide the best service to the ‘greatest number at the lowest.rates. Only the united effort which insures continuous development of tele- phone communication can carry through that controlling purpose of the Bell System. “ BELL SYSTEM” Better Service AMERICAN TELEPHONE AND TELEGRAPH COMPANY AND ASSOCIATED COMPANIES One Policy, One System, Universal Service, and all directed toward 4 Cameras and Lenses of eve Shams “ Equal to new. Save money. Write now-for Free Bargain Book and Catalog ~ listing hundreds of sgupoee! Pee hige bargains in slight- ly used and new and supplies. All oods sold on O "days" | vee Trial. Money ack if ‘not satisfied dealing with u e have. been in the photo- graphic business over 19 years. Write now take no chances CENTRAL CAMERA CO., Dept. 68, 124 S. Wabash Ave., Chicago ya We want one exclusive repre- Vp sentative in each locali eg end the new Mellinger fg hand made tires. Miles. (N _ ds), Shi ped p pre. oO secon pps nm approval. sections farni: fo So you get our ae & RUG! 1 hy Wate — MFL LINGER TIRE e 1004 Oak St., LAUNDRY SUPERINTENDENCE AND MANAGEMENT There are 10,000 Laundries in this country. Properly qualified Superinten- dents and Managers are needed. The Power Laundry Cooperative Course trains men in two years, half time spent in actual laundry work for wages. Other Intensive Two Year Day Courses INDUSTRIAL MECHANICAL ENGINEERING INDUSTRIAL ELECTRICAL ENGINEERING ARCHITECTURE INDUSTRIAL ART For special announcement write the OHIO MECHANICS INSTITUTE Dept. B 89 Cincinnati, | Oo.

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MakeYourBike -aMotorcycle FASY to do and at low cost. Your old “foot power’’ bicycle can be quickly transformed to a speedy, easy-run- ning high power Motorcycle with the Shaw Motor Attachment. Fits any men’s bicycle of any make or size. Chain drive model can be attached in less than an hour. A boy can put it on. No special tools or knowledge necessary. SHAWN’. Thousands in use. A light weight 2% H-P motor of wonderful efficiency. Simple to attach. Everything furnished complete. Every owner enthusiastic. All materials are guaranteed. Get one NOW. FREE Write at once for Free Book and Low Direct Factory Price on the Shaw Attachment, also the Shaw Motor-bicycle--a complete power maciine at a low price. SHAW MANUFACTURING CO. | Dept. 1468 Galesburg, Kansas BE A RAILWAY: TRAFFIC INSPECTOR Many Openings at Good Pay Earn up to $250.00 and $300.00 per month, expenses paid, in this fascinating new proiession. Interesting, pleasant work; travel or remain near home. Brings you in contact with prominent railway officials ; splendid oppor- tunities. We Guarantee You a Position Prepare in three months spare- time study at home. Any aver- age man can qualify. We then guarantee you a position at $110.00 a month, expenses paid, or refund ‘aged money. ou take no risk. Don’t Delay—Investigate Now while more are needed than are trained. Send today for free Booklet No. D-229. Standard Business Training Institute BUFFALO, EARN $75 TO $200 A WEEK A repairing, retreading and com- pletely rebuilding old tires, with the greatest money making ma- chine of its kind on the market. The Adams-Barre system of tire repairing enables you to turn out a superior grade of this kind of work that brings huge profits. It operctes at one-third the cost of inferior outfits, and present tire prices only give it added advantages over other systems. With an Adams-Barre machine you can completely reconstruct old worn-out tires that others would not tackle. $ eotete lnctrastions x mail or at once, at one of the A ully-equippe ams-Barre schools. Big opportunity. Write NOW for details. - — ™ The Adams-Barre Co.,1244 N.HighSt.,Colmbes,0. 12 Independent Economical Transportation Write-for Catalog “S” Cleveland LIGHTWEIGHT MOTORCYCLE @THE CLEVELAND MOTORCYCLE CO. CLEVELAND, USA 4 ewe skip-jack sail- boat can be put together for about twenty dollars and many hundred dollars worth of pure fun may be had with it in a single season. The boat is really a scow with a sail on it. It is splendid to swim from, since it wiil not tip. It must be admitted right here that tris is not a rough-water boat. The frame of the craft ismade with 1-i7. timber. Th=z bottom boards, which run crosswise, are °4 in. thick. Only matched lumber should be used for this purpose. Two heavy ribs made of 2-in. material run down the center of the craft. and form a well that runs the length of the boat. A centerboard or keel is made to fit into this well. This board is so arranged that it may be lifted up out of the water. You Should Protect the Drainpipe Outlets 1 phil of drainpipes should be pro- tected from the caving in of the sur- rounding earth and from the entrance of rodents. Dirt caving in at the end of the drain causes the water to back up into it and sediment to settle, eventually clogging ~~ HINGE 4 FLAP RETAINING WALL pee ot tay J My Wy” Afi, wood STRIP @ Ww Muti On WY fit ead y > fill r. ” dls ? it . we RN) i | oC, AA." DRAIN PIPE > ——SS —_ WIRE Pp yt" ‘ \\“ \w Yo N “dl Ait ve de a \ . Voie hw Yu SPILL APRON a ASK — Mt Mtg “ua uw Here the proper way of constructing a drainpipe outlet is shown. The flap will keep out the rats up the pipe. Vermin and rodents enter and sometimes are killed, thus stopping up the drains. The illustration shows how to protect the end of the drainpipe with a concrete curb, also the method of preventing rodents from entering. A concrete retaining wall should be built around the drain end and a spill apron extended as shown to prevent the dirt from being washed out and under- mining the structure. The retaining wall is not built until the drain is in place and it should be so built that the end of the drain projects about 12 in. beyond the wall. A hinged metal flap cut from some light-weight tin or sheet iron and of a slightly larger diameter than the drainpipe is used to close the end of the pipe. Prob- ably a sheet of zinc or copper would prove 90 On smooth waters you may derive much pleasure from this craft; try to build one Popular Science Monthly Why Not Make a Skip-Jack Sailboat? The depth of the craft should be about 1 ft., although this will depend upon the judgment of the builder. The top of the craft is made slightly round to al- low the water to run off. A length of 12 ft. and a width of 3 ft. will make a boat sufficiently large to hold three to four per- sons. All of the crev- ices should be filled up with putty, marine glue, or coal tar and the outside of the boat must be given at least two coats of good paint. It is provided with a simple rudder. A mutton-leg sail is carried. This should measure about 10 ft. on every side. The mast of the sail is held in a socket made of a short length of iron pipe. This is provid- ed with a capped end and set in flush with the deck. Such an arrangement prevents water from getting into the hold of the boat. more satisfactory as it would not rust. A brass hinge is riveted or bolted to one side of the flap and then in turn screwed to the end of a piece of hard wood about 12 in. in length. This piece of wood is placed along the top of the pipe and securely fastened to it with copper wire as shown. . With a ‘little adjustment the flap will hang over the end of the pipe. It will open auto- matically to allow the waste water to pass out, but will prevent anything from entering.—B. FRANCIS DASHIELL. An Adjustable Platform Step for the Ladder HEN doing much work on a ladder it is very tiresome to stand for a long time on the rungs. This small step or plat- form bolted to the ladder will make the work much easier. | Two straps of flat bar iron are bent into the shape shown in the illustration. The loops in the bent ends of the straps are just large enough to slip firmly over the rungs of the ladder. An oak board 12 in. wide and equal in length to the width of the ladder, is securely bolted to the two iron SPRUNG IN PLACE Working while standing on a ladder becomes less tiresome if you can rest on a platform like this straps as shown. If care is used in the con- struction and the board is not too wide nor too long, it will be an easy matter to step on or over it from above or below.

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August, 1921 Moor Rowboats to Prevent Them from Chafing HEN rowboats are moored to the shore or a dock by a bowline, the wind, tide, or current tends to swing them back and forth and chafe them against per- | manent projections. This can be remedied as follows: Drop a heavy mooring anchor about three boat- lengths from the shore. A wooden buoy, attached to the mooring by a chain, floats on the surface of the water. A pulley is attached to the buoy. Attach one metal ring to the bow and another to the stern of the boat, and provide a strong mooring- rope long enough to reach from the shore to the mooring and back again. Fasten a snap-hook to each end. Run the rope through the pulley and snap one hook to a ring on the stern of the boat as shown. The rope is slung over a mooring-cleat on the pier and the free end with its hook is snapped on the ring at the If your boat is moored in this way, it will be safe from injury by chafing against the pier or post bow. Then, by pulling the rope one way or the other, the boat can be run out to the buoy or brought to the shore. The hooks are snapped together when the boat is unfastened around the cleat on shore.—L. B. ROBBINS. Try a Safety-Razor Blade for Card-Cutting SERVICEABLE little device for cut- ting and trimming paper or cardboard or for bevel cutting, such as is required in making mats, can be easily made by utiliz- ing discarded safety-razor blades. The device as shown includes a short hardwood block, triangular in cross section. N Bevel Cut Vertical Cut Paper or cardboard may be cut with an old safety-razor blade attached to a prism of wood On one of the right-angle surfaces of the block a brass plate 114 in. by % in. by 1/16 in. is fastened by two screws located 3% in. and }% in. respectively from the ends of the plate. These screws pass through the two holes in the razor blade for vertical cut- ting or, as shown in the perspective view, through one hole. The inclination of the plate on the face of the wood block should be about 30 de- grees to the bottom edge to obtain the best results.—EVERETT ROGERS. YOUR TROUBLES ARE OVER The most important part of your car is the little Transformer, which cures the uneven, missing, jerky motor and makes self starters live up to their name, “vK Van Kerr Transformers Decrease gasoline consumption—give greater power —reduce carbon deposits. They can be attached in a few minutes, and from that time on you will have a sweet, smoothly running motor which starts easily even : 7 é' = c in zero weather. * 2°ESIS Does Your Motor Pump Oil? Don’t Worry! Van Kerr Transformers cure the giving greater power and leaving troubles which are due to this con- no carbon. The Van Kerr method dition. Their patented, fireproof of ignition eliminates the necessity construction allows the current of for reboring cylinders and install- electricity to be broken inthe open _ing new piston rings and instantly air without danger of igniting any removes the difficulty caused by vapors under the hood. Thé more motors pumping oil. For pleasure combustible spark so produced, cars, tractors, motor-cyckes and burns every particle of oil and gas, gas engines. We Will Send You a Set of Transformers Altach them iy parcel post. Write us today and tell us your dealer’s name and the kind yourself. All of car you drive. Send no money. Simply pay the postman $2.00 for a d js four-cylinder set or $2.50 fora six-cylinder set. Use them ten days and if i you need ts you are not satisfied that they do all we say they will, return them and you } yrs geno will get your money back. : and a pair of pliers. |The Van Kerr Co., Dept. 82, 3160 N. Clark St., Chicago Over 100,000 satisfied customers are using Van Kerr Transformers LE ELEGRAPHY AT HOM WIRELESS AND MOASE TEACH YOURSELF in half the usual time, at trifling cost, * with the wonderful OMNIGRAPH ; Automatic Trans- mitter. Sends you unlimited Morse or Continental messages, at any speed, just as an expert operator would. Adopted by U. S. Gov’t., Leading Colleges, Universities — Telegraph Schools throughout United States and Canada. 4 Styles. Catalogue free. OMNIGRAPH MFG. CO. ‘ 26R Cortlandt St. New York These five different keys are the only set of its kind to insure your safety and serve for emergencies. They open and test thousands of different door and padlocks. When you are away or asleep how safe is your lock? Or should you lose your keys _canothers open? It's better to know than worry or be sorry. Don’t delay; only, $1,00 for complete set with novel key chain. MASTER KEY CO. wiitwauKee, wis. TO FORD, OVERLAND 4, CHEVROLET 490, and DODGE OWNERS The most complete and instructive book ever published on Prol the Life, Increasing the Power, Speed, and En- durance of automobile motors. Explains where aeroplane and racing motors get their amazing power, and tells how the power of the above motors may be in- creased tremendously. Whether you drive a Passenger car, Tru PoWER-SPEED k, or are a peed Demon’’ you will find this book intensly interesting. Also contains use- ful tables and data. Free for the asking. Dunn Mfg. Co., Box S, Clarinda, lowa. iF ILLUSTRATED ARPENTERS, Bricklayers. Mechanics, Plumb- You Can Save *50.00 Cers, Pipefitters, Boilermakers, Sheet Metal By recovering your old Workers, Shipfitters, Structural Workers and others ante td ann yourself can earn more money if they know how to read Blue We sth ted che sioeth datnady nee + Prints. By our method, we train you ina short time. $G 55 all makes and models of cars. Write for talogue B, stating trade, e Any pereoe. that can drivea car can put iton. We furnish We also teach drafting. Bea Draftsman! Earn big and == xq instructions; Roof and quar- money. Books and tools FREE. Write for Catalog G. ‘a Parcels Post ters sewed together with . rear curtain, fasteners, yreits and tecks. All complete, Give us Columbia Con espondence School Est. 1904 t ® and we will send you aed our catalogue with samples and quote you exact price. Dept. 27, Drexel Bidg.. Phila., Pa. LIBERTY TOP & TIRE CO. Dept. E8, Cincinnati, O. Semi CORD TIRE MILLER TREADS aa “Geared To The RoaG” ) rly WRITTEN 5000 MILE GUARANTEE .\, Most modern and lasting of reconstructed tires. These semi-cords are heavily WV reinforced with Genuine New Miller “*geared to the road”’ treads as illustrated in : yy ad and will give wonderfulservice. Donot confuse them with sewed or half soled x tires. A remarkable low factory purchase enables us to offer these guaranteed tires at ' 28x3 $ 7.00 31x4 = $10.50 32x414 $12.75 36x4% $14.50 y 30x3 7.25 32x4 11.25 33x44 13.25 33x5 15.00 p 30x314 = 8.60 33x4 11.75 34x414 = 14.00 35x5 15.50 32x34 9.50 34x4 12.00 35x4%4 =: 14.15 37x5 15.75 _. STANDARD-MAKE TUBE FREE WITH EACH TIRE ap at ex le Send No Money Lan Ae he ‘demaition. ae ‘cash with order, deduct 5%. ‘ost you nothing to send for tire. Write today. Return if not like new. HUDSON TIRE CORP., 241-A Harrison & Peoria Sts., Chicago, fil. 91

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ETT ER tire re- air method ismak- ingmen RICH! Chas, SEvans, carpenter, . ” ast 60, now MAKING $100.00 a week in shop shown here. Gibbard of Mich., age 62, learned TIRE SURGERY, —. shop ‘jn small town, writes: “*C: = receipts f or May, June and July, 1920, $30,000 aa E ) is easy to learn. I will teach you in two weeks, ted on roed to fortune. Car into automo- e field that bas rich. It 66,000. 09 § n naam Se for John W. Blair. Pri. in 12 aid ag of New Zea- tel Get oy Tote coupon nce for FREE book. Mr. Haywood, Pres., 1276 Cap: tot — = tedlanepelia, im ind Dear ir: Send full a at 2 of Tire eee as sonal to get into big paying business quick) Name Address. 21 Jewel Illinois ¥ The greatest watch value ever offered. Unequalled for beauty, accuracy and relia- bility. 21 ruby and sap- phire jewels —adjusted to positions, tempera- ture and isochronism, 20 year gold-filled case. 10 Days’ Free Trial \ Wear it for 10 Days at our risk. Note its absolute exactness. If at the end of ten days youare not satisfied, just send it back at our expense. Knife and Chain Free We are offering for a tentend time this handsome gold-fi knife and chain ABSOLUTELY FREE. Only lic a Day | Just send your name and address. The watch, chain and knife come to you, prepaid. Give the expressman $8.50 as adeposit. If after 10 days, you do not wish to keep them, return at our expense; your deposit will be refunded instantly. Trialis absolutely free. If youkeep the watch pay $3.40 a month until full price of $42.50 is paid. This splendid watch will cost youless than lic aday. Aci at once. Address Dept. 471-N. CAPITAL $1,000,000 “‘The House of Quality ’’ L. W. SWEET, iNc. 1650-1660 Broadway New York Gas, Air, Water, Gasoline Pumping by vacuum or pressure of air with ner? BROS. AIR PUMPS pests Positive widely used for gasoline measuring pumps, printing press paper feeders, package wrappers, bottle filling de- vices, fuel oil heating outfits, gas fur- naces and blow ipes, agitating chemical and Mm , Other solutions. sand blast- \ ing, testing or leaks, vacu- um cleaning, priming engines and pumps, milking, vacuum chucks, lowing away stamp- ings and cuttings from presses and machines. Catalog wien * No 2A 281 Walker St., N.Y. Only $45.00 For This ted Complete Save exorbitant freight rates and one-half A original cost by arts cut to Not Paper Patterns ny one can Parts Complete —— le this job. Oomeicte with hood, radiator ‘shell, instroment board, uphol ng. me | parts, wood parts, bolt screws, etc. Flat Fadiator Shell ‘urnished made mp. Designed low with lack of Price set up $90, further particulars on request wing resistance. Eng. Dent. 122 The Central Auto Supply Co. louisville. Ky. How to CARBON-PILE rheostat is a form of resistance that is very useful in the small laboratory. It is surprising how few amateur electricians know of this device. In a pile of flat pieces of carbon the electrical resistance will depend upon the contact between the individual pieces, and this contact will in turn depend upon the pressure applied. With a very light pres- sure the electrical resistance will be high, and with a heavier pressure the resistance will drop. If the pressure is applied gradually, the resistance, of course, can be varied accord- ingly. The carbon pile used in the little rheo- stat shown in the illustration is made by cutting up old battery carbons. These should be cut carefully so that they will fit smoothly together. If you should have a lathe at hand, the cutting can be done on that; otherwise a hacksaw can be used. If a hacksaw is used, an improvised miter box must be pressed into service to insure accurate TIGHTENING SCREW Old battery carbons are the material from which this useful rheostat for the sinall laboratory may be made Popular Science Monthly Make a Carbon-Pile Rheostat cutting. After the pieces of carbon are cut out they should be | treated individually with a smooth file. The workman will now be ready to pro- ceed with the con- struction of the little wooden frame that holds the blocks. Each of the end pieces has a heavy wooden screw through it. These screws are used to adjust the pressure on the plates. The pointed ends of the screws come in contact with metal pieces between which the carbon pile is pressed. If the screws were allowed to press into the carbon pieces, the carbon pieces would break. A binding-post is then mounted at each end of the rheostat and a flexible cord connects the binding-posts with the metal plates. The device is used in the same way as an ordinary rheostat and the resistance is ad- justed by using a screwdriver. Consider- able current can be passed through this carbon-pile resistance without causing an appreciable increase in the temperature of the composing elements. FLEXIBLE Steam Turbine with a Tin-Can Boiler ) ene little steam turbine will give the boys a great amount of pleasure. The boiler is made from an old tin can. best type of can is the kind that syrup PATTERN OF ROTOR PLACE CAN ON STOVE The principle of the steain turbine may be clearly illustrated by this home- made apparatus comes in. Such cans are provided with a tight-fitting cover. A little arm of metal is soldered to the top of the can as shown. A hole is drilled in one end of this to act as a bearing for the shaft carrying the rotor. The rotor is made from a piece of light tin about 11% in. in diameter. This is cut with shears as shown. The blades are then bent into a fan shape by twisting them around slightly. They should all be twisted in the same direction. A hole is drilled through the center of the rotor. A piece of heavy wire is forced through the hole and held with a drop of solder. A circle of sheet brass is cut out and a hole drilled through the center so that it will fit over the shaft carrying the rotor. The opposite end of the rotor is first filed to a point and a little piece of brass is drilled out so that it will accommodate 92 The, this pointed end of the shaft. This is really an improvised thrust-bearing. The brass- bearing piece is.soldered to the tin can so that the hole will come directly under the hole in the bearing-arm that was previously soldered in place. The fly-wheel is also held in place with a drop of solder. A nozzle made of a small piece of brass tubing is then placed in the position shown. It will be necessary to drill a hole through the cover to accommodate this. It is held in place with a drop of solder. The can is now filled one quarter full of water and placed on a hot stove. In a few minutes the little rotor will begin to spin.—L. LAURIER. A Chandelier Devised from a Bicycle-Wheel Hoop Ot? bicycle-wheel hoops can be used to make chandeliers suitable for use in a summer cottage or the den. Four chains are attached to a hoop. These meet at the top, where they are attached to the fifth chain, which reaches to the center of the hoop. This chain is attached to an electric light socket and the wires run down the chain. If the builder desires, he can cut a piece of composite board to cover the top. The light drops through the center. Crépe- paper of any color desired is cut and put around the edge of the hoop as shown in the illustration. Beautify your den with a chandelier like this

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, eee August, 1921 You Can Produce Gas from Old Newspapers ty newspapers yield a- considerable volume of illuminating gas when used as described below. Get an old syrup-can complete with an airtight fitting lid. \| i, Punch or drill a WZ hole in the lid to GAS BURNER NY = receive a length of Yj-in. brass gas- piping, and make a good joint. Now fill the can with old news- papers, close the can with the air- tight lid, and place the retort over a fire. In three or four minutes a gas will issue from the brass pipe, and on applying a match, will burn with a luminous flame A - 2 until the paper in an interesting ex- the retort is used periment up. If desired, a length of rubber tubing can be connected with the retort pipe to convey the gas wherever wanted.—GEORGE H. HOLDEN. Nails Hammered in the Wall so They Will Hold ia order to nail anything to a lath-and- plaster wall, follow these directions. Inside the wall are upright timbers to which the laths are nailed, these are almost invariably 16 in. apart, so all that you have to do is to measure one or a series of 16 in. from a door or window or corner, and you will find firm holding, but it is well to test with a fine bradawl before driving a heavy nail. If you want to hang a heavy object and cannot do it just where the upright comes, nail a strip of wood from one to the next, and fasten to that. A light object may be LATH = Locate the uprights before you attempt to drive any nails in your walls. It will save you trouble hung to a lath by boring first and then using a fine screw, letting it work its way gently into the lath. If you wish to fasten anything to a con- crete wall, which turns the points of the nail, carefully remove a few inches of the wall-paper, then with a small cold chisel or old screwdriver or twist-drill make a hole 14 to 34 in. round and deep enough for your nail; into it drive tightly a wooden plug fixed with plaster of paris or cement, smooth it over, replace the wali-paper and drive in your nail or screw. 1090171 MAGNET- LITE ‘Che Lamp with the Magnet Grip" The Trouble Light that Never Fails ON a dark country road, dim side street or in poorly lighted garage, Magnet-Lite stays right where you put it and puts the light exactly where you want it. By means of the power- ful electro-magnet in its base, it sticks like a burr to any metal part of your car. . It requires no holding and leaves - both hands free to examine, adjust or repair. The small size of Magnet-Lite per- mits its entrance into the least acces- sible parts where trouble often lurks, yet it is large enough to illuminate adequately any night repair operation. Vibrations or jars cannot break the tenacious grip of the powerful electro- magnet. When not needed, the magnet may be switched off without shutting off the light. Paint or enamel does not affect the magnet-grip. Magnet-Lite connects with the dash by means of a plug, and ample cord is furn’shed for work anywhere on the longest car or truck. It may be in- stantly connected and as quickly adjusted to the desired position. Magnet-Lite is packed in a strong japanned container, convenient for tool kit, seat tray or door pocket. It is shipped anywhere, charges pre- paid, complete with 144 inch cord and dash connection plug for either single or double contact, on the re- ceipt of coupon and $5.00. Or you may save time by getting it from your nearest dealer. Price ing Magnet-Lite has become a practical necessity to all motorists who drive at night. It supplies the great de- mand for a trouble light that need not be held and that is instantly available for any purpose. It has as many uses i as there are things that may happen to your car. Sy ae a ee a ee ORY GY BY Ge we oP y The Magnet Light Company Check oO 1509 S. Michi A Postal order (J . Wienigan Avenue Express order (J Chicago, Illinois Currency oO Gentlemen: Enclosed find $5.00 for which | you will ship at once, charges prepaid, one Magnet-Lite complete. a Please Indicate: Directly from the car or from the handy storage bat- a tery carrier, it isa great convenience for the motor-camper. Made Solely by : a The Magnet Light Co. 1509 s. Michigan Ave., Chicago BSc ~ Sonesta agli EET VUEBUUUUUUUU UUM oss civ. Sie) Construction of Induction Coils and Transformers, by Thomas Stanley Curtis. Full of practical notes and instruction. Tells you both the why and the how, Little is left to guess work. Open and closed core transformers are both taken up. For a practical in- struction book on the whole subject this one is hard to coat for the Price, postpaid. 25 cents POPULAR SCIENCE MONTHLY 225 West 39th Street New York SIMPLE WIRELESS TELEPHONES AND HOW TO MAKE THEM. An elemental book on the principles, con- struction and use of an arc system of wireless telephony. Price, 25 cents postpaid, Book Department, POPULAR SCIENCE MONTHLY 225 West 39th Street ELECTRIC LIGHT The latest electtic light, no batteries to buy or electric. maintain this midget electric light. Safe, simple / and smell, no wicks or oil, no chimneys to clean New York L bills to pay. Anyone can install and inexpensive. No more smoke or break, just as safe in the barn, garage and clothes closet as in any open YPN room, always ready for use, day or night. A touch on the switch an 5 F you instantly have a bright electric light. No matter where you live this hght can be install t is not affected by heat or cold. Many homes have installed this electric light in their halls, closets, pantries, barns, sheds, llars, garages, etc., with good results. It is an extremely useful light which no household should be without. The reason for this bright electric light is that the lighting bulb is fitted with a drawn Tungsten filament wire which is much more efficient and durable, besides giving a 300% in- crease in light as compared with the ordinary carbon lamp. The power system furnished with this lighting outfit is somewhat similar to the electric power battery described. Each electric light outfit includes the following: Complete directions and plans, copper wire, insulated wire holders, knife switch, drop light fixture with socket, friction tape, battery protector, -maroon shade, national mazda globe. Our dry battery compound, which assists in renewing pons tn the current and our current renewing system with whic you can renew the current at home without expense. With every day use one recharge usually lasts two to three weeks. This electric lighting outfit is undoubtedly the most practical and durable electric light of low cost and long service ever devi Special price to introduce these electric lighting outfits $1.00, le Outside the U. S. $1.25. Order now direct from this advertisement. A. B. ELECTRIC CO. 1636 So. Lawndale Ave., 93 CHICAGO

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for YOW' Wireless expansion Sweeping over world like wildire! Biz opportunities now open—on land anisea. Salaries amouit to $200 to $500 a month. New metioi makes Wireless amazingly easy to levn—AT HOME IN YOUR SPARE TIME. Wonde-ful invention also teaches you code in half usuiltime. This Institute the original and largest S$: 1001 teic ling Wireless by mail. Officially recoz- nizel by U.S. Government. Graduates in every pict of the world, holding fine positions. This fascinating, uncrowlei field needs you too. It’s reu un to stuly it, uniter our new method, in the simmer or any other time. Just a little of your $9ure time now quickly prepares you for the world’s ‘ \stest-zrowinz field — Wireless. Fine pay, big © ‘portunities, travel if you want it, and a splendid tuture. Write for FREE BOOK, “Wireless, tae Opportunity of To-day," and special Short Time Offer. Mail postcard or letter NOW! NATIONAL RADIO INSTITUTE, Dept. 88, Washington, D.C. WHITING-ADAMS BRUSHES Send for Illustrated Literature JOHN L. WHITING-J. J. ADAMS CO. BOSTON, U.S.A. Brush Manufacturers for Over 112 Years and the Largest in the World BATTERY CHARGING PAYS EIG €& $25 Puts an H-B Battery Charger in Your Shop p a) Pay the balance on long, easy terms out of your profits. You can make BIG MONEY with an H-B Battery Charger. Size for 10, 16, 32 or 70 batteries. : Choose size needed. Write @ | for information. ' HOBART BROS. CO. Box S87 Troy,Ohio Canada: J. V. Elliott, Hamilton, Ont. ===. Build This Phonograph Yourself TREMENDOUS SAVING IN COST: Fasy, fascinating work, with our SIMPLIFIED Ss. We furnish blue prints, diagrams, motor, cabinet pieces, ready-built horn, etc. You don’t need to be a cabinet-maker. A few hours assembling and you will have a fine in- strument at one-quarter the regular retail price, AGENTS MAKE MONEY mm ing and selling these instruments. Write today for full details and our FREE OFFER. Address:— MODERN PHONOGRAPH SUPPLY CO. Springer Building 313 So, Clinron St. _ ____ CHICAGO, ILL. Here’s a Book You WANT! INDUSTRIAL ALCOHOL By F. B. WRIGHT It gives full directions, illustrated with original draw- ings of the necessary apparatus, for the manufacture of what is considered by many to be the coming fuel for au- tomobiles, motor boats, heating, cooking, lighting, etc. Send your order TODAY before present edition is exhausted Here’s an Idea on Washing Photographic Prints ERE is a good sujr- gestion for the amateur photog- rapher. When the water is al- lowed to run full ferce into the photographic washing-tray, a current is cre- ated. The prints come in contact with one another and stick togeth- er. They are prevented from receiving the This illustrates a proper amount good method of of washing in washing prints this way. A glass placed in the tray prevents this. water.—GEORGE BENDER. How to Remove Kinks in Wire The water from the faucet is allowed to fall into the glass. It overflows from this into the tray. This causes very little dis- turbance and practically no current is pro- duced, although the tray receives sufficient Popular Science Monthly tubing are then pinched together in the vise. A hole of the right diameter is then drilled through the flat end and the ter- minal is completed and all ready to be used.—CARL ROYER. This Window-Lock Will Actually Lock ete and as nearly burglar-proof as possible is the window-lock that is shown below. All that is necessary to con- struct this lock is a small drill and some round steel rod. Close the windows and drill a hole through one corner of the bottom sash and not quite through the upper one. Then make a pin of the steel rod with an eye in one end. The pin should be long enough to go clear to the bottom of the hole in the upper | sash. A cord tied to tke eye and to a screw- eye.in tke sash will prevent the pin frem drop- ping to the floor I} and becoming ‘4M lost. n" With the pin STRING shoved hcme in the two holes there is no way , 1ff . 4-§ tt // , ty fi Wf nd fe FSI AAS x / FMLS, ff Ug ia / / eee STEEL PIN, 4 Simple and effect- ive for taking kinks out of wire HEN I needed wire of a gage that I did not have at hand, I obtained a helical spring and un- coiled it. To remove the kinks that remained in the wire, I fast- ened one end to a hook in the wall and_ the other to a large weight. Then I looped the wire around a_ short metal rod and drew the rod back and forth several times, thus removing the kinks. — FRANK HARAZIM. Wire Terminals Made from Brass Tubing pene amateur mechanic may make his own wire terminals for electrical work if he has on hand a few feet of copper or brass tubing of the right diameter. The tubing is first cut off the proper length in the lathe or with a hacksaw. If a number of the terminals are to be made, it is best to cut them off in the lathe, since this SZ 4 This pin with the screw-end locks the window for a burglar to remove it with- out removing the glass and he can- not raise or lower either sash with- out smashing them to pieces if good steel is used for the pin. To prevent the pin from working itself loose, the end of the pin should have a few. threads so that it can be securely screwed into the hole of the top sash of the win- dow.—L. B. ROBBINS. Build This Shoe-Polisher at Home \ ITH this little machine much of the hard labor is taken out of cleaning shoes. Using this device the shoes can be polished with one hand. WOODEN BLOCK One end of the SHOE CLOTH Back-strain from stooping while polish- ing the shoes may be prevented by the use of this mechanical device produces a neater job. When this is done, the pieces of tubing should be heated and allowed to cool slowly. This will DRILL HOLE Wire terminals may Price $2.50 Postpaid SPON & CHAMBERLAIN, 120 Liberty Street, New York be made from metal tubing 94 anneal the metal. The ends of the rag is placed between a wooden clamp attached to the end of two window-shade springs. The rag then passes through two wire frames mounted on a wooden block as shown above. The foot is placed on this block with the rag over the top. Pulling on the free end of the rag will cause it ~ to move back and forth over the shoe.—MATTHEW Potts.

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August, 1921 Special 30 day offer introducing “‘Cardanta”’ aie be NTAIN TOOTH BRUSH Post- 0) Outfit com- let - paid * ee din: paste cartridge. **CARDANTA"’ saves 8 opera- tions every time you clean your Is sanitary, teeth, convenient, economical and some, etatie Brush and Paste in one. te tube is in the handle. Just turn the: a | like an ever re —~ 4 pencil and the paste comes out on the brus! FOR EVERYBODY EVERYWHERE *“‘CARDANTA"”’ is convenient at home or it is as easily carried as a fountain pen in pocket, hand bag or traveling case. Itis aheolutel sanitary, made from fine quality aluminum, NICKELED FINISHED. No composition, no rubber or pn Babar oom but pure aluminum. ‘High qualit: yi imported bristles set in alumi- num. A brush unequalled for sanitary and lasting quali- ties, and extremely light and convenient. Extra paste tubes filled with PY ihe high quality tooth paste, Agents Wanted. Good f territory open for sales and jobbers. first-class salesmen wanted Send a dollar for sample Aleta complete. Order N e cannot guarantee this offer longer than 30 days. Money back if not satisfied. CARDANTA BRUSH CO., pethorr Micnican’ U. S.A. (ULDAVOONEOUGUEUNOOGAOOUAUAAUUOAETAG AAR Trained Auto Salesmen Sell Motor Cars— Trucks— Tractors Get into this interesting business which is growing so rapidly and paying big rewards for ability. There is a shortage of trained salesmen—a big demand for the man who knows how to get the business. We offer a complete course in Automotive Salesmanship, cov- ering the entire field from getting prospect to closing sale. Can be easily mastered. Inexpensive. Previous auto experience not necessary. Complete Course of 20 books, $12.50. Write today. Dept. 10. LESLIE-DONALD COMPANY 15 West 37th St.,New York, N. Y. UUIUUUULANAUOOUOUUUUANNANUUEOUUUUULASONOOOOOEUUUUUAAANONUEOUUUUAOAAAGAAE UU Convert Your Bicycle Into a Motor-Cycle by using a STEFFEY MOTOR ATTACHMENT. Fits any or- dinary wheel, arch or diamond frame. Easy toattach. On market over 21 years. Send stamp for circulars. STEFFEY MFG. CO., 5025 Brown St., Phila., Pa. RAISE RABBITS ke and GUINEA PIGS FOR US Large profits-easily-quickly. We sup- ply stock and buy all you raise. Our illustrated book ‘Common Sense Rab- bit and Guinea Pig Raising,’’ Contract and Prospectus 10c, tells you how. Quarterly Yay Journal keeps you posted, 20c a year. Both book and journal le OUTDOOR ENTERPRISE CO. Live Stock Dept. 508, Kansas City, Mo. Raise Silver . Foxes Easy toraise. Larger profits than any other live stock rais- ing. Stands strictest investi- gation. Recommended by Government. Four different plans. One will suit you. - Complete description sent free. Ask for it today. C. T. DRYZ, Box 1013, EAGLE RIVER, WIS. Be Your Own Boss! |! In the outdoor amusement business. Our games earn big money anywhere people congregate for amusement. 1 Parks, Carnivals, Fairs, Home- -comings, orga ee i Pleasant, easy work. No experience necessary. | investment, big, sure profits. We have made -* | of people independent. Write today for literature. PENN NOVELTY CO. | Tesi Buttonwood Strest, Dept. B. Phila., Pa. | “BOWLEGS andKNOCK-KNEES" } UNSIGHTLY | j SEND FOR BOOKLET SHOWING PHOTOS OF MEN WITH AND WITHOUT The Perfect Leg Forms PERFECT SALES CO. 140 W.Mayheld Ave., Dept. 45, Chicago, Ill , Learn to Dance Youcanlearn Fox-Trot t,One-Step, Two- Step, Waltz and latest ** e-minute ciety dances in your own } = ate by the —~+ hw Peak System of Mail Instruction. - agram Meth: Sasi music needec; thousands tush successfully; success absolu tely uarantee, Write for8S 4 Teras Send today for E information and ing! fay low offer. Dept. S, Improvising a Depth-Gage in an Emergency “THE depth ofa hole can be measured very well with this little improvised depth-gage which is made of a ruler and a Piece of card- board. Two slits are cut in the cardboard to enable a pocket ruler to pass through them. The cardboard should be fairly stiff so that it will stay in whatever posi- tion it is placed on the ruler, T he _ illustra- tion shows the method of using the improvised Use slit cardboard gage. —L. for making this LAURIER. depth-gage A Homemade Punch for Use in Embroidering A HANDY punch for embroidering, etc., may be made of a phonograph needle and a common clutch pencil. The sketches involved. The thick or so-called “loud” needle is most suitable Soften its blunt end by fHHow to make a practical embroi- pio dery-punch dius ; —o, ie i j 2 > FLAME \ } : ° WA WEAT BLUNT i V —_—_—___—_— J CLUTCH : PENCIL : CUT NOTCH wiTH *“ 3 CORNERED FILE heating it in the gas flame until it is red- hot—then allow it to cool. Cut a fine in- dentation all around at the blunt end of the needle. A jeweler’s file is the best for the purpose. The point can also be inverted in the clutch to carry the punch in the pocket. Of course the pencil is in no way impaired.—C. NYE. To Produce a Black Stain on Polished Brass = is described a‘dip for black on polished brass parts that is recom- mended by an authority: Liquid ammonia—3 gal. Saturate with carbonate of copper to excess. Thatvis, add the carbonate of copper as long as it dissolves and then add more so that there is a marked excess. Then add water— 1 gal. Clean articles in potash, rinse, dip in cyanide, rinse and immerse in dip, having the dip stirred up well. When black, remove, rinse, and dry. When the dip is not in use, keep it well covered. When it oot VILLIAM CHANDL! RP mM. 5 Broadway? Cricagd, In, below illustrate the several simple steps | A Remarkable Book P ry Health VI-REX VIOLET RAYS Learn of the tremendous curative power—the manifold uses of VI-REX Violet Rays in treating almost every known human ailment—Nikola Tes- la’s great discovery! This book also contains charts and diagrams of the nervous system and organic locations, and fully describes just how the Vi-Rex Violet Ray works its many miracles. Written in a simple style—devoid of all technical language. Send for this FREE Book—you will find many astounding and health-giving facts. and Vitality Permanently Yours Increase your store of energy, revitalize your worn out cells, make every fibre of your body tingle with new vim and vigor. As a quick relief from pain, Vi- Rex Violet Rays have no equal. Headaches, nervousness, skin blemishes and many other com- plaints vanish as if by magic through this marvelous treatment. The Vi-Rex is not a Vibrator. It does not contract the muscles or shock the nerves. Its magic rays pass through every cell and tissue, creating ‘“‘cellular massage’ —the most beneficial electrical treatment known. It leaves no soreness after use, only a delightful sensation of agreeable re- lief. No shock. bration. Try the Wonders of VIOLET RAYS TEN DAYS FREE Find out how Violet Rays will help you—demonstrate for yourself. Read what hundreds of users say about the Vi-Rex and the astonishing results which have been obtained. Learn why itis the most economical and practical machine of its kind available. There is no limit to its beneficial powers. Just mail the coupon or send a postal. Doit NOW. No vi- Vi- a Byperese CO., Dept. 1507 West Madison Street, Chicago am. whe me, without any cost or obligation, your free book describing your Violet Ray Machine, and details of your free trial offer. becomes weak, add more carbonate of copper and ammonia. 95 LE EE PET rR CT eT er Address...... SE oe CAIRas 0 iecnce coencccednctceveneecsekasesttharace .

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Electrician’s Wiring Manual Tools and Symbols —Preliminary Suggestions on Building Wiring— Moulding—Flexible Conduit—Rigid Conduit—Fixtures and Their Instal- lation—Switches —General Sugges- tions on House Wiring—Installing Household Electrical Utensils—Wires and Cords — Motors —Transfcrmers —Switchboards and Panels—Motion Picture Theater—Bell Circuits, An- nunciator - Circuits, Gas Lighters, Burglar Alarms, Bell Transformers, Door Lock—Elevators—Wiring in Damp Places—Outside Wiring— Grounding and Ground Detectors— Inspector’s Report on a_ Defective Electrical Equipment — Estimating and Specifications—Tables and For- mulas—Electrical Circuits, Calcula- tion of Wiring, Line Losses and Na- tional Electrical Code Discussed for the Beginner—Alternating Currents Simply Explained—Some Things the Electrician Should Know About Storage Batteries—Underwriters’ Re- quirements in the Installation of Wireless Telegraph Equipment— Practical Kinks. There are many formulas and tables which are of great value to the electrician. This is a book every wide-awake electrician or any one who wishes to do any wiring should own. Don’t take chances, but be sure your work will pass the fire in- spector. This Manual may save you 100 times the price of the book. 448 Pages, 414 Illustrations, Hand- some Flexible binding. Pocket size. Price, postpaid, $2.50. Experiments With 110- Volt Alternating Current By J. D. ADAMS Here at last is a book that devel- ops a practical working familiarity with the alternating current—the form in which electricity is used in every home. The author shows how this can be done in an inter- esting and inexpensive way. The only way to gain a thorough understanding of electricity as it is used commercially is by direct personal experiment. The knowl- edge thus gained is of vastly more value and importance than that acquired from the performance of the stereotyped series of battery experiments so uniformly de- scribed in the text-books. 256 pages, 135 illustrations. Price, postpaid, $1.75 Construction of Small Al- ternating Current Motors By PROF. A. E. WATSON Brown University This book contains complete in- structions for building small alter- nating current motors in several sizes. The designs will be found in harmony with those of the very best manufacturers and they can be worked out by the amateur for making useful instruments. Some of the subjects taken up are “Characteristic Features of Alternating Current Motors,”’ “Construction of a One-Half Horsepower, Single Phase Induc- tion Motor,” ‘‘Procedure in Test- ing and Using an Alternating Current Generator or Synchron- ous Motor.” Clear, concise directions and careful drawings are features of this book. Fully Illustrated. Price, $1.50

Popular Science Monthly How You Can Economize on Hacksaw Blades ACKSAW breakages will seldom occu ° if the following simple device is used. It may be made from a few strips of hard wood *s in. wide by 1% in. thick and about the length of the saw-blade. One strip of wood is placed on each side of the blade in the frame, and a paper clip then grips the whole tightly so that the saw back is held rigid during use. Of course, one can employ this method only on small work, but it gives more con- fidence in work- ing on the heavier material. — GEO. H. HOLDEN. HACK-SAW

This device means a saving in hack- saw blades Cool Beverages without the Use of Ice eA a. and simple is this method of cooling beverages so that they are refreshing as well as palatable. It is based on the rapid evaporation of water. The liquid to be cooled is placed in a preferably thin-walled container. Around this is wrapped a towel well soaked with cold water. This is then placed in the direct current of air produced by an electric fan. Care should be taken to have the towel neither too thick nor too wet. Lacking an electric fan, the towel-wrapped container may be placed in an open window, but the electric fan produces a stronger and more dependable air current than stray breezes afford. This method of cooling drink was used by the ancient Egyptians. Jars of baked Nile mud, which were semi-porous amd which allowed a certain amount of evapor- ation, were filled with the none too clean

ee

Modern application of a_ principle known to and utilized by the ancient Egyptians Nile river water and then set in the cool shade. The native Egyptians use this method to-day and it well answers the pur- pose in a country where, save in hotels frequented by tourists, the use of ice is unknown.—W. T. PERRY. News-Drawings Can Be Easily Transferred ELT \ oz. yellow soap in 10 oz. of hot water and when cold add 2 oz. of turpentine. Float the. picture in this and when it has absorbed all the moisture it

New York 225 West 39th Street,

can, place it face down on a piece of bristol- 96

Popular Science Monthly - board, absortb he superfluous moisture with a piece of blotting-paper, lay a piece of tracing- or wrapping-paper over this, carefully fixing one edge with pins or glue so that it will not move, and rub from the fixed edge with a burnisher, and your picture will come cleanly on to the board. A fair impression may be obtained by lightly rubbing the picture with a paraffin- wax candle and then placing it face down on the paper or board, rubbing the back with the burnisher. The fingernail makes a fair burnisher.—E. A. MCCANN. For Holding Screws in a Vise with a Clamp ‘Tse simple little clamp is very useful in the workshop to hold small screws securely so that it is possible to file or saw them. It is made of -in. strap steel about 1 in. wide und 6 in. long. It can be quickly and easily made by first filing the notches in the jaws to the depth desired and bending the ends in a vise at right angles to thestrip of metal. The two ends are then bent around a_ piece of pipe until they nearly meet. Tempering is unnecessary as the little spring needed will al- 3 NOTCHES B STRAP 10 Suit STEEL

SLOT ‘ied if

|

VISE JAWS The notches are cut . to hold different sized ways be left in screws the metal. When a screw is placed in the notches and the clamp is inserted between the-jaws of a vise, there is little chance for the screw to slip. As many as three notches may be cut in the jaws of this clamp to accommodate various sized screws. Toy Boats Constructed with Pliable Cardboard A FAIRLY pliable cardboard may be used to construct toy boats. The bottom, sides, and stern can be cut out as shown. Adhesive tape is pasted along the edge inside and outside. This tape must be slit at intervals so that it will take a curve without buckling. The boat is immersed in a pan of hot paraffin and allowed to remain there several minutes. It is taken out and cooled off and then given a coat of shellac. A water-tight little craft can be produced in this way. The cross pieces are merely glued in.—JOSEPH B. MORAN. (| MASTS

WOODEN CROSS PIECES

‘K___ ADHESIVE TAPE

ai » | “STIFF CARDBOARD Childre: | defive great enjoyment from pilayit< with this water-tight little crait

Page 85

August, 1921 To Hang Things Upon a Needle Point Any boy interested in mechanics can tell you why Moore Push-less Hangers The Hanger with the Twist will safely hold heavy pictures to the walls. Note the scientific angle to the point. Forlight pictures, use the world-famous Moore Push-Pins. 71. Neither will mar wall paper, plaster or wood ‘fj , work. § Suggest a use and we'll send samples free. | I) Sold by hardware, stationery, 10 drug and photo supply stores Cput. everywhere MOORE PUSH-PIN CO., 11-8 Berkley Street, Philadelphia, Pa. Operate a Used Car Business! Make from $50.00 to $500.00 on Every Deal The Used Car Business offers UNLIMITED POSSIBILITIES for ambitious men, and is a field that is not crowded. If you can drive a car you are fully qualified to enter this most profitable and fascinating vocation. I will send you my complete printed instructions, ‘How To Operate A Used Car Business,” upon receipt of $3.00. By using my instructions you operate without investing any capital. Benefit by my five years’ experience and BE YOUR OWN BOSS. Send Today. PERRY J. SPENCER 116 Atlas Street, Akron, Ohio p21 Jewels $ c°amonth | The 21-Jewel Burlington te sold to on the very. ial terms (after yt ay ET ay} only month—no Interest. You are under po obligation to buy, for full information. A le’ ter or post card wil Burlington Watch Company, iy ease 19th Street and Marshall Bivd. Chicago, wimols “DON’T SHOUT” “T hear you. Ican hear now as wellasanybody. ‘How?’ — THE MORLEY ONE. I'vea pairin rain ears now, but they are invisible. I would not know had them in, myself, only that I hear all right." The Morley Phone for the DEAF to the ears what fom are to the eyes. Ovisible, comfortable tless and harmless. Abyone can adjust it. Over one hundred thousand sold, Write for booklet and testimonials, THE MORLEY CO., Dept. 797, 26 South 15th Street, Philadelphia \ ; Build and Fly Model Aeroplanes Bulld a Model A tenet toot wih 6 Fa ees Asignen bar anae ike a real one. Drawings and Building and Firing Instructions you can easily buil exact, 3ft. duplicates of bi Aero- wings an ‘or the one you will build: Curtiss INED- -2Training ‘Plane, De Havilland Battle ‘Plane, NC-4 2 Cc Naval Seaplane,Curtiss Military Tractor, ne ag | Monoplane, Nieu- port eee Taube M iy Sree each Catalogue p See AL Model Postpaid eroplanes and Supplies, 5c Postpaid. Ideal tential & Supply Co., Cor. . Houston & Wooster Sts., N.Y.C. Print Your Own cards, circulars, labels, tage, menus Press $12. Job Presi situp up, CUTS SEXPENSRIN TALE. B ALL OUTLAY. Pays for 7 iteslf in short time. Will last : Y foryears. Easy to use, printed Px a BIG PRORTT. Write factory * ¥ r actory cu Nae Y ODAY for press catalog, TYPE, cards, paper,envelopes, | >. (o4 ES Te) °) THE PRESS CO.; 0-83, Meriden,Conn. Add a Revolving Ridetes to the Kitchen OUSEKEEPERS who do their own cooking will find the revolving roaster here described and illustrated a valuable addition to their kitchen equip- ment. The roasting-rod or -spit should be of iron or steel, a few inches longer than the roasting-pan. When in use, the spit rests in the bear- ings riveted to the edge of the end parts of the pan. One end of the spit is bent to By the addition of this revolving spit to the roasting- pan cooking will be made much easier form a crank with a handle. A ratchet wheel is driven on the spit to a point near the handle and engages a spring riveted to the end piece of the pan. The fowl or meat to be roasted is per- forated as nearly as possible through its center by the spit. The rod is then placed in position in its bearings so that part of the roast is submerged in the gravy at the bottom of the pan. By means of the crank the roast may be turned to any position so as to bring different parts in contact with the gravy. It is not necessary to take the pan from the oven to change the position of the roast. A slight turn of the handle from time to time is all that is necessary till the roast is browned.— W. A. JACKSON. One Way of Truing Up the Emery Wheel RINDING-WHEELS get out of true very easily. In the smaller shops the mechanic does not always have a wheel- truing device at hand. A good substitute will be found in a piece of a broken wheel. If this is held against the sur- face of a revolv- ing wheel, it will true it up quick- ly, but it must be held to the wheel with con- siderable pres- _—An effective method sure. — JOSEPH of truing a grinding- B. MORAN. | wheel 97 ~ PIECE OF BROKEN SS [NS NV SHTTUHHUOMUUUAMUTUATUVEGUOOUODVEUUOUSANOEUULUUEVUDLAOLUCONUSUUAUCQECUOLEAESLMUONETAS my /' =P 4 The world’s most famous bandmaster. John Philip Sousa, says: “‘I consider the excel- lence of Conn instruments enhances the musical value of any organization at least 50 per cent.” TTINITIININITINII MINT IO TTI PUM SCOOT = asbiesiinali Suits Your Talent? OME one instrument is your in- strument, best suited to develop your musical “bump.” Is it the cornet, saxophone or trombone; the clarinet, oboe or flute? Our new Free Book will help you decide. Illustrates and describes playing qualities and opportunities of all band and orchestra instru- ments. Telis how to practice for quick mastery. Sousa himself gives you the secrets of his success. Conn instruments are easiest of all toplay. Built by exclusive processes in world’s largest band instrument factories. Played by greatest solo- ists; awarded highest honors at world expositions. Free Trial; Easy Payments on any instrument. Send coupon for book and details of free trial plan; no obligation. A Gaarantee Band With Every Conn Cc. G. CONN, Ltd. 832 Conn Bldg., Elkhart, Indiana NEW YORK CONN COMPANY 233-5-7 West 47th Street TAVEUEEUD ERATOR a ET OE i Ga: ma yy | COTTE THAT OTIDPPDUD ND TOVAT TATED ATODDOUDUOLECERUAUUUUCEUTLCHEELUTVCCQUCTAST OUD COT ET AVOCA CUE HT THCUO OUTED ODED ITANCIDUOVUNUOSEINLEAU ETON VETERUTOPTA ED STQODNUUODUOTAT COUSTEAU EET TE ESS ATT LT TD 7g Cc. G. Conn, Ltd. 832 Conn Bldg., Elkhart, Indiana Gentlemen; Please send me, free. a copy of “Success in Music and How to Win It,”’ and de- tails of your free trial plan (mention instrument).

Page 86

Popular Science Monthly AIRTIGHT COPPER KETTLES Guaranteed made of 100% pure solid heavy cold-rolled copper, complete and per fect inevery detail. Special spunned covers, extra strong handles, positively airtight. No. 2 Gal. size, $5.00 No. 15 Gal. size, $15.00 “ “ 7.00 “ “ 20. 00 Safety-Razor-Blade Holder from a Clothespin ae ttgaoncerigers safety-razor blades may be used for ripping seams, by. the photographer for cutting masks or mats and in many other ways. The difficulty of their use lies in the inability to comfortably handle them alone. No. 4 * 7 No. 6 “ “« t2 No. 25 “ “25.00 No. 8 “ * 22 No. 30 “ “« 30.00 No. 10 “ “ 12.00 No. 50 “ “$0.00 These kettles are also tinned inside for $2.50 extra. Also made in wash-boiler shapes, sizes 12, 15, 20. 25 gallons at $1.00 per gallon. _Posi- tively airtight. $3.00 extra per boiler for tinning inside, packed in strong, plain wooden boxes. vas go by American Railway Express. Send draft or money order to cover, or we will ship CcC.O.D. Orders shipped same day received. THE MAXWELL KUNIN CO., Not Inc. 2640 W. Madison St., pt.J. Chicago, Ill. 40 years of honest merchandising your guarantee of our reliability. ste Settee, RPE, ee HIGH SCHOOL Pa TWO YEARS If the handle of your safety razor is lost, use a clothespin A clothespin, though, can be turned, in a few minutes, into a very satisfactory handle for the blades. A small hole is bored through one prong of the pin halfway between the end and the base, and a screw inserted in the hole. By tightening the screw the prongs of the clothespin close, and by inserting a razor blade between them, it may be held fast. The use of the handle makes the handling of the blade less dangerous.—FRED C. DAVIS. You Want to Earn Big Money! Ard you will not be satisfied unless you earn steady promotion. But are you prepared for the job ahead of you? s Do you measure up to the a that insures success? For a more responsible position a fairly good education is necessary. To write a sensible business letter, to prepare estimates, to figure cost and to com- pute interest, you must have a certain amount of preparation, All this you must be able to do before you will earn promotion, Many business houses hire no men whose general snownetee & not equal to a high school course. y? Because big business refuses to burden itself with men who are barred from promotion by the lack elementary education, Can You Qualify for a Better Position? We have a plan whereby you can. We can give you a complete but simplified high school course in two years, giving you all the essentials that form the foundation of practical business. It will prepare you to hold your own where competition is keen and exacting. Donot doubt your ability, but make up your mind to it and you will soon have the requirements that will bring you A Lunch-Box Made from an Old Book LUNCH-BOX ox, es or 0 can be made Selva. ae eae Set onder = om from an old book ; of the proper thickness and size. With a straight- edge and an old safety-razor blade, the center of the pages are cut out as shown. When this is done, a thick preparation of glue is smeared around the inside and over this pieces of cardboard, cut to the proper ‘ ACENTS WANTED. BIC MONEY. Oliver Oi-Gas Burner & Machine Co., Oldest Largest Mfr's Oil-Gas Burners. 2007-H PINE STREET, ST, LOUIS, MO, Build This Car This nifty little car You will enjoy the contents volume of this success and big money. YOU CAN DO IT. Let us show you how to get on the road to success. It will not cost you a single working hour. We are so sure of being able to help you that we will cheerfully return to you, at the end of ten lessons, every cent ou sent usif you are not absolutely satisfied. at fairer offer can we make you? Write book will stiffen up and a very good little | Seeman: (A esate, size, are placed. When the glue sets, the IDanc ing Made fa SY | lunch-box will be the result. Some care and patience will have to be taken to see that the cutting is carried on as evenly as possible and keeping the pages uniform.—JOSEPH B. MORAN. today. It costs you nothing but a stamp. AMERICAN SCHOOL Dept. H.C. 75, Drexel Ave. & 58th St., Chicago IN POP-CORN CRISPETTES Protect Your Bank Account Against Forgers Ts efficient check-protector may be , Dept. H.C. 75, Chicago, tit er made from an old table-fork and a é Explain how I can qualify for position checked: 8 milled nut. The nut should be wide eves Architect 85,000 t016,000)......Lawyer $5,000 to $15,000© enough to fit between the outer prongs of ‘ een Building Contractor echani . y nntomas ieee fae — sa ee 410,000) the fork near the shank. Now heat and Motorcycle Barg ains cut off the-fork prongs about 1 in. from the S AVE 25%, to 65% shank, and turn up on Slightly, used and Rebuilt Motor 64,000 10,000] -+++-.Shop Superintendent see Attomobile AL — nm €3,000 to $7,008 $2,500 to $4,000)......Employmen Meneger 3] to $10,000 @ | the ends asshown. cycles, Side | Cars, Johnson | Motor If the nut be of ee dees Gee Ga t evveeCIVil ws ty $4,000 ir to $16,000)... Engineer \@ »....Stractural Engineer to —_— for —_ yo eae —— ane 5 : Sav es n \- a wide bore, insert dreds of Bargains in used, rebuilt and a plug so as to re- new machines,supplies, accessories, etc. “* duce the bore to take a small 4-in. AMERICAN MOTOR CYCLE CO : Dept. 802, 2047 W. Chicago Ave., CHICAGO bolt and nut. This done, ad- just the nut in @ DY, place, pass the bolt ~ through the fork ends and nut and tighten the bolt.— GEO. H. HOLDEN. juccesses. ‘or booklet, Long Eakins Co., g47 High St., Springfield. Ohio FORK HANDLE countant $7,000 to $16,000 - ewe Accountant & Auditor |----Telephone Engineer $2,500 to $7,000 $2,500 to $5,000 0 eveeDraftsman & Designer|......Telegraph Engineer conf] $2, $2,500 to $6, essa High School Graduate In two years @ cose ire Insura E t Seba e Geaicascancancameamcancd Dollars in Hares We pay $7.00to$18.50 and upa pair and express charges. Big Profits. We furnish guaranteed high grade stock and buy all you raise. Use backyard, barn, cellar, attic. Con- tractand Illustrated Catalog Free. STANDARD FOOD AND FUR ASS’N 407C Broadway New York PS PRONG TURNED UP BOLT AND NUT Run the wheel over the figures on the check 98

Page 87

August, 1921. Es True-Tone Saxophone * A Buescher True-Tone Sazophone #) 4 opens the way for you to greatly in- / Vz AN crease your income, opportunities, (Ak ee popularity and pleasure. Easiest 4 of ail wind instruments to play —you can learn toplay the scale is jn an hour and in a few days (@ be playing popular airs, tice is @ pleasure. Saxophone Book Sear To Play To Pay

Tells you when to use Saxophone — singly, Panels in the Screen Door Make It Rainproof T a total expense of about one dollar a screen door can be converted into a weatherproof storm door, making it do duty twelve months a year. This may be accomplished with the aid of a sheet of waterproofed wallboard and a few acces- sories. To,convert your screen door into a storm door cut a sheet of wallboard, which can be obtained from any builder or mill at small cost, to fit exactly in the panels of the

in — or in regular band; how to transpose cello parts in or tra and many other things you would like toknow. You can order any Buescher instrument 7 Free Trial and try it six days without obligation. If perfectly satisfied, pay for it on easy payments to suit your convenience. Mention the instrument interested in and a complete catalog will be mailed fr (26) BUESCHER BAND INSTRUMENT co. Makers of Everything in Band and Orchestra Instruments door. Place the WATERPROOF boards __ tightly TURN- i : Burrons «62S ainst the screen molding. This will make them level with the screen mold- 3126 Buescher Block, Elkhart, Indiana

A dependable fast cutting Log Saw at the right price. Powerful 4-cycle engine —> with two fly- wheels gives steady power, sawing -_ or trees, or for § belt work. Lever Sontrol. oreo Feed. 00 'F.0.8. KC.

me) Cuts An IV Size we 4 WITTE EN 2228 Oakland Ave., - Ka ’ S228Empire Bids’, - Pittebot ne Pittsburgh, Pa.

With little capital, BE YOUR OWN BOSS. MAKE MORE MONEY ou can establish a business in’ your ing, and if they have been fitted carefully, they will make the door weather- proof. Procure some turn-buttons, at- taching them to the screen mold- ing to hold the board in posi- tion. Before placing the wallboard in position several coats of paint, of the same color as the door, should be applied, and if a small win- dow is desired in the top panel, cut out a hole of the desired size and cover it with a pane of glass about an inch larger than hole. Take some cheap picture-molding, fit it around the glass and bolt it to the wallboard panel by means of several

Wallboard panels will make the screen door rainproof own home town and make $10 to $30 per day with Anderson’s Steam Vulcanizers. ter work, less cost and bigger pro There are Andersen schools in is near you Better schooling plus finest <ipiement makes Anderson We teach you the famous An- — me aa of vulcanizing the operation of the An- de lerson Super-Heated Steam Vulcanizer and Retreader. Takes 5 to 10 days in school and costs If at any time tee buy an Anderson Vulcan- zer, we refund your $35

y you per day for each of the 0 school days, because we sell the work you do. Write today. ANDERSON STEAM VULCANIZER CO. 102 Williams Bldg. Indianapolis, Ind.

We will tell you how to make money.

HL ee $372 in 17 Da Mr. C. J. Weeks, 2319 An Ave., Jacksonville, Fia., easily made this money by selling Sparko-Gaps! $100 in Less Than One Week Irving Laighton, Vineland, poe rea;

P . Norton, of Vernon, N. Y., earns bi ry 4 selling Sparko-Gaps M Schuster, of Brooklyn, N. Y., sold eight the first day. This is an oppertuniy ‘ SPARKO-GAP of alife-time to build up ,, (Govermment-Approved) an automobile business Qo jevibatit is and. what 3 of your own. Exclusive ofthe spark plug. It increases engine territory, noinvestment to intensify ‘sperk rk approved by, the required. Write today United Leer being sold Thousands for proposition. Large guarantecd profits eee 5 ° ” SPARKO-GAP CO. tak 39th Sts in Baby will sleep in this basket as well as in an expensive carriage

Standard Underwoods 5-Year Guarantee ot thle nuine Standard Visible Writ- ing Under-

wood newly rebuilt, mucb = a on than factory stove-bolts. In the spring simply remove the panels of wallboard and you have a screen door as before.—R. NEWBECKER. How a Basket Became a Baby-Carriage HOWN in the illustration is a baby- carriage that was made from parts of an old folding baby-carriage, two boards, a few strips of wood, and an old clothes- basket. The construction of the carriage

ice, yours £eris boson and then easy monthly payments, =. ord TYPEWRITER EMPORIUM C-214 Shipman ren aise is clearly shown in the picture and requires no additional explanation. It may be stated, however, that the bassinet, though perhaps not very ornamental, was found to be perfectly safe and gave satisfaction to mother and baby.—PauL J. Kurtz.

99 8 :

igo | OF BW ciel for Young Men

ND Ta A TS OO a Good Pay for You in Auto Business Hundreds of good jobs paying around $50a week are open for Swee- ney trained men. Garages, repair shops, welding or

EBT TBE FBLA ADI ER. tae <a, “Ba

vulcanizing shops, automobile agen- 9 : N cies, etc., have LE EM SBE BEEBE LEOGESA, Bos Bhs,“ M. writtea to the E.J.SWEENEY | Sweeney School PRESIDENT | asking for compe-

,

tent mechanics. The Sweeney School at Kansas City is the world’s largest and most famous auto and tractor school. It trains men in eight weeks by the Sweeney System of Practical Experience. This system under Mr. Sweeney’s direction turned out over 5,000 army mechanics during the war. Many thousands of Sweeney trained men hold responsible and profit- able positions in the automobile business. An interesting feature of this training is that no previous experience is required. No books are used and everything is taught by working with your own hands. It is so simple that a deaf and dumb man learned to be a good mechanic in eight weeks. The Sweeney School publishes a great number of applications from garages, repair shops, etc., asking for men. “I want a head mechanic and will pay $50 a week” writes one concern. ‘Want two mechanics. Pay 60 cents an hour. Please wire,”’ writes another. LEARN IN 8 WEEKS tus SWEENEY SYSTEM Mr. Sweeney publishes a beautifully illus- trated 72-page catalog that tells all about opportunities right now in the auto and tractor business. He will send this free without any obligation, together with the Sweeney News, an interesting paper and full information about the demand for trained men. This literature plainly shows how any young man mechanically inclined who is willing to work hard for a few weeks can fit himself not only for a job, but for real success in life as owner of his own business. There are many opportunities in both city and rural districts. as aa name today for free catalog to E. J. EENEY, President, Sweeney School, Rh Tae and Aviation, Dept. 879, Kansas City, Mo MAIL THE

For Big Free Catalog Mail This Coupon EMORY J. SWEENEY, President Dept. 879, Sweeney Building, Kansas City, Mo. Please send me free without any obligation on my part your 72-page catalog and your Sweeney School News. Tell me of the opportunities in the Auto and Tractor Business. Peewee eee were reseeseeeeeseeeeeeereee®

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will give our opinion as to its PATENTS SECURE A PATENT, send for Our Guide Book, HOW TO GET A PATENT, sent Free on request. Tells our Terms, Methods, etc. Send model or sketch and description of your invention and we patentable nature. ‘ 1 NAMB .ccccccccccccccccccccccccccccvces eecccceee: RANDOLPH & CO.z © srpsur.i..cccecccccssescssesseeseeseen 130 F St, N. W., Washington, D. C. a Oe STE IF YOU HAVE AN INVENTION and DESIRE TO LEARN HOW TO pocccscscsscc Arithmetic of Electricity A practical treatise on electrical calculations of all kinds reduced to a series of rules. $1.50 Postpaid. POPULAR SCIENCE MONTHLY 225 West 39th Street New York eet pe To the Man With an Idea fe I offer a most comprehensive, ex- perienced, efficient service for his prompt, legal protection and the development of his proposition. Send sketch, or model and description, for advice as to cost, search through prior United States patents, etc. Pre- liminary advice gladly furnished with- out charge. : My experience and familiarity with . various arts, frequently enable me to : accurately advise clients as to probable patentability before they go to any expense. Booklet of valuable information and form for properly disclosing your idea, free on request. rite today. RICHARD B. OWEN Patent Lawyer 6 Owen Building, Washington,D.C. 2276-D Woolworth Building, New York City Booklet Free Highest References Promptness Assured Best Results Send drawing or model for preliminary examination of Patent Office records and report as to patentability All Business Given Prompt and Proper Attention WATSON E. COLEMAN, Patent Lawyer, 624 F St., Washington, D. C. A Hand-Book of Essen- PATENT-SENSE tial Information and Advice relative to Patents, Trade- Marks; Assignment, Sale or Licensing of Rights; Abstracts from Leading Decisions; State Laws on Patent and Trade-Mark Property. FREE! Write LACEY & LACEY Dept. B, Washington, D.C. Established 1869 PATENTS TRADE-MARKS COPYRIGHTS Send for our free book of patent information Beale & Park %5.s::"teees.2: ¢ SIXTH EDITION yeu os DON'T LOSE YOUR RIGHTS} TO PATENT PROTECTION Before disclosing your invention to anyone send for blank form *‘‘EVIDENCE OF CON- CEPTION” to be signed and witnessed. A sample form together with printed instructions will show youjust how to work up your evi- dence and establish thesame before filing ap- plication for patent. As registered patent at- torneys we represent hundreds of inventors all 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 om on request. Ask for them,—a post card 0. PATENTS AND TRADE MARKS 274 Ouray Bidg. WASHINGTON, D. C. Originators of forms ‘‘Evidence of Conception.” PATENTS WRITE TODAY FOR FREE BOOK ABOUT PATENTS, etc., and ‘‘Record of Invention” which contains forms to establish evidence of conception of your invention. :The book tells all about Patents, their usual cost, how to proceed and contains good sound prac- tical facts every inventor should know. ‘‘Record of Invention” should be filled out, signed and witnessed before you disclose your invention to anyone. By entrusting your case to me you will receive prompt personal service and real co-operation in connection with the determination of your rights, the protection of your invention and the development of your proposition. My fees are always reasonable. Highest references furnished. Pre- liminary advice without charge. Write today. Delays are dangerous. J. REANEY KELLY PATENT LAWYER 612-16 Columbian Bldg., Washington, D. C. Popular Science Monthly Make Your Individual Drinking-Cup of Paper [>" a square piece of paper a drinking- cup may be made that will hold water and will be more sanitary than a public drinking-cup. Fold the sheet of paper diagonally as ‘ FOLD ON THE - DOTTED LINES EVEN = ee or ‘m7 Even an improvised paper cup is better and more sanitary than a public drinking-cup shown in the diagram, then fold the two corners A and B along the dotted lines shown in Figs. 2 and 3 until the folded paper appears as shown in Fig. 4. Then turn the two flaps down on both sides and you will obtain the cup illustrated in Fig. 5. If hard paper is used, the cup will hold water a long time.—F, EVERARD JORDAN. Wiring Flower-Pots to the Porch Railing LOWER-POTS can be secured to the railing of the porch or the window-sill as shown in the illustration. A staple is placed on each side of the pot and a wire is fastened to one sta- ple, stretched over the top of the flow- er-pot, and then fastened to the other staple. An- other wireis wound around the side of the pot and twist- ed around the first wire a few times where it crosses it. Both wires must . be drawn as taut Wire the flower-pot as possible, so as and prevent accident to hold the flower- pot firmly. The strongest wind will not blow the pot to the ground, and stray cats prowling around in the night will not knock it over.—ARTHUR GOLDENBAUM. How to Fasten a Pulley on the End of a Shaft I HAVE illustrated here a very practical method of placing a small pulley on a shaft. A hole is first drilled in the shaft and the pulley put in _ tion. The shaft is a = then spread out by inserting a ta- pered punch in the hole and hitting it a smart blow with a hammer. The taper on the punch ae should not be too small, as this would make it difficult to pull the punch out. —G. BENDER. Vjyuuiy Dt. KE Wy) SSLLITTTTA Y UL 4 — ( A few taps of the . hammer will fasten the pulley o> ot ~~ aaa car wee | Ue hee

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eo oe. August, 1921 An Eolian Harp that Is Simply Constructed HESE are rather pleasant things in the summer, as when the wind blows, they murmur and hum and sing. If you wish to make an eolian harp, first decide where you are going to have it, whether in the open window, in place of one of the panes, or in a fanlight or ven- tilator opening; any opening that the wind has access to will do. Then make a wooden frame to fit. Make it fairly stiff with a top and bottom of hard wood; on to this frame glue a very thin sheet of wood having two openings in it, similar to those in a violin. This thin sheet must be flush with the out- side of the window, so that the frame pro- jects into the room. Now get some screw-eyes and screw them halfway into the top and bottom of THIN BOARD WITH TWO OPENINGS ET TINVATNT HINT sceew-eves 2 ( UGuT STRINGS BRIDGE The wind and an eolian harp will entertain you with a continuous performance the frame, close to the back. The number used is a matter of taste; the more strings there are, the louder the harp. To these screw-eyes stretch gut strings, similar to those used for violins and banjos. Fasten them tightly and put two bridges under them of sufficient height so that the strain comes on the bridges, then screw up the eyes until you have sufficient tension; the tighter the strings the higher the note; they may be of various tensions or tuned to one note.—E. A. McCANN. This Vise Will Successfully Hold Small Tubing SMALL tubing cannot be held in a heavy vise without danger of bending it. This little device, which is made of four pieces of cold rolled steel, will be found SWINGING aN Friction between pipe and blocks may be increased by tightening the thumb-screw very practical for this purpose. The bot tom piece has two projections so that it can be screwed to the bench. The hole in the top piece through which the bolt passes is of an oblong shape so that the piece can swing on its pivot. A winged nut is used to clamp the top piece down. The tubing is inserted in the hole. If the mechanic wishes, he may make a vise with ‘holes of different sizes. ) oe ee ee ee ee eee a eee we ie ee ee es es PATENTS weer SPECIAL OFFER BREE, OPINION as To PATENTABLE NATURE Before disclosing an invention, the inventor should write for our blank form *‘Evidence of Conception.’’ This should be signed and witnessed and if returned to us to- gether with model or sketch and description of the inven- tion, we will give our opinion as to its patentable nature. Our Three Books Mailed Free to Inventors Our Illustrated Guide BOOK HOW TOOBTAIN A PATENT Sent FREE on Request Contains full instructions regarding Patents, Trade-Marks, Foreign Patents. Our » Methods, Terms, and 100 Mechanical Move- ZY ments illustrated and described, Articles on Patent Practice and Procedure, and Law Points for inventors. OUR TRADE MARK BOOK Shows the value and necessity of Trade-Mark Protection and gives information regarding unfair competition. OUR FOREIGN BOOK We have Direct Agencies in all Foreign Countries. Write for our illustrated Guide Book on Foreign Patents. SPECIALIZATION Our Staff The field of invention is so vast that it is impossible for any one man to become an expert in all the different classes of invention. Only those practically skilled in the class to which the invention relates are capable of rendering efficient service. For this reason Victor J. Evans & Co. employ a number of patent lawyers and mechanical experts who have been selected for their special knowledge and ability in certain lines of invention. Each case is placed in charge of experts in the classes in which the invention relates. THE VALUE OF YOUR PATENT Will depend much upon the skill and care with which your case is prosecuted in the United States Patent Office. This work will receive the benefit of skill and experi- ence acquired by a long and successful practice. We spare neither time nor pains to secure the broadest possible patents that the inventions will warrant. That every case entrusted to us receives our best efforts, and that our work is done consistently, skillfully and thoroughly is evidenced by the many unsolicited letters of commenda- tion that we receive constantly from our clients. We will furnish upon request lists of clients from any State in the Union for whom we have secured patents. Our New York, Philadelphia, Pittsburgh, Chicago, and San Francisco Offices Owing to the growth of our business we have established for the benefit of one clients Branch Offices in New York City, Philadelphia, Pa., Pittsburgh, Pa., Chicago, Ill., and San Francisco, Cal. These brarich offices being located in these large commercial cities, together with our Main Office located nearthe U. S. Patent office, in Washington, enables us to more promptly handle the business of our clients, particularly as ‘the branch offices are in constant touch with the Main Office and fully equipped to handle patent business in all its branches. Highest References—Prompt Attention—Reasonable Terms | VICTOR J. EVANS & CO. Patent Attorneys 4 ' , New York Offices Philadelphia Offices Pittsburgh Offices 1007 Woolworth Bldg. 135 S. Broad Street 514 Empire Bldg. ae TU Mm Ke] ‘\ AS eH : ‘ i es i AN i oe e Chicago Offices, 1114 Tacoma Bldg. San Francisco Offices, Hobart Bldg. Main Offices, 760 9th Street, Washington, D.C. Gentlemen: Please send me FREE OF CHARGE your books as described above. i] | ae) hi WKN il | 101

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PATENTS write fully and freely to Munn & ing its operation. Patents, etc. If you are a reader of SCIENTIFIC AMERICAN ou are probably aware of the act that it has a special appeal to the inventor. Each issue contains a description of a large number of recently pat- ented inventions. Pending pat- ent legislation as well as the most recent rulings of the Patent Office and the courts are considered in its columns. SOLICITORS OF PATENTS Tower Building - Chicago, San Francisco, Calif. F YOU HAVE AN INVENTION which you wish to patent you - o. for advice in regard to the best way of obtaining protection. Please send sketches or a model of your invention and a description of the device, explain- All communications are strictly confi- dential. Our vast practice, extending over a period of seventy years, enables us in many cases to advise in regard to patentability without any expense to the client. Our Hand-Book on Patents is. sent free on request. This explains our methods, terms, etc., in regard to Patents, Trade Marks, Foreign MUNN & CO. 683 Woolworth Building, New York 624 F Street, Washington, D. _ Hobart Bldg., 582 Market Street, If it is a successful wireless phone it is a De Forest invention have to junk | you save money on replacements if you start with the De Forest In- terpanel system. apparatus. can buy panels one at a time. station. upon the number of panels used. mounted in any position. Each panel only 9 inches high. Get the Interpanel Idea Send for catalog 85 of Highest Grade Radio Apparatus 1415 Sedgwick Ave., New York City RADIOPHONE REG. U.S. PAT. OFF. For Telegraph and Telephone Buy wireless you don’t Each panel constitutes a complete Each panel sold separately—you First two panels make a receiving The range of any station depends The uniform height of the panels permits the same logical, easy con- struction characteristic of sectional book cases. Interpanel sets may be De Forest Radio Tel. & Tel. Co. Inventors, Licensers and Manufacturers = Old Trunk as a Tool-Chest for Wall HE owner of a little shop has a number of tools that, because of their value, he wished to keep safe from dampness and the hands of those who visited the shop. He fitted the top inside surface of an old Went o3) lal Careful mechanics who like to keep their tools in order will find this cabinet a great aid and protection steamer-trunk as shown in the illustration, and screwed the bottom to the wall through two strips of wood. The careful mechanic hangs his tools in the spaces provided and keeps them under lock and key when they are not in actual use.—CHARLES A. GODDARD. How to Make a Set of Dinner Chimes A® old phonograph record may be used in making a set of dinner chimes. Notches are cut as shown. There will be as many notches as there are tubes. A string is run from the center of the phono- OLD PHONOGRAPH RECORD BRASS TUBES OF DIFFERENT LENGTHS Home-made chimes like these, calling the family to-meals, will add to the pleasure of the housekeeper and her family graph record and several other strings branch off from this, each one holding a length of thin brass tubing. Notches cut in the edge of the disk prevent the strings from slipping. Holes are drilled through the top of the tubing to attach the string. The tubes should be of different lengths so that different tones will be produced. A small piece of doweling may be used to strike the tubing.—JosrerH B. MoRAN. 102 Popular Science Monthly CAN YOU think of a simple, practical idea that will fill one of the many ree quests we have on file for new inven. tions? It may mean a fortune for you. Thousands of things are needed Ricut Now. Your brainscan help. Send to- day for our great new book—“‘Inven- tions and Trade Marks, Their Protection and _ Exploitation’’ and learn more about making money from ideas than you ever knew before. It tells many things that are wanted, £00. A postal will do— it is free. PATENTS ADVERTISED For SALE FREE We help our clients, Without charge, to get the dollars out of their ideas—having facilities Done others possess. Advice free. In INVENTION And poor at cacy °° HMM” MANUFACTURING SUPPLEMENT. AMERICAN INDUSTRIES, INC. 201 Patent Dept., ' WASHINGTON, D. C. Published for the Man with an idea. Send for free sample copy: One year'ssub- il ecription 50c. AUTO OWNERS Save half of your tire cost by usi Double-Mileage, Doubie-Tr Tires, Guaranteed 6GOOO Miles. 4 We lead, others try to follow. 4 They are reconstructed of _— J grese material — hardly ever blow out. They are only guaranteed for “¥ 6000 miles, but have run from 8000 Order today jg THOMA TTRRITRRENDAATAN I, 900000 IMME ae ee = Soo Send us sketch or model for patestabiity upinion and exact cost of patent. Our boo! jow to Obtain a Patent” Sent Free on re- quest. It tells how to ly for Patents, Trade Marks, Foreign Patents, Gesstiaiin, etc.; gives information on Patent Procedure; tells what every should know. Th ds of I clients, are our references. CHANDLEE & CHANDLEE, 25 Years’ Experience ‘3, who are our Free Book onPATENTS| hemaion on Patents. Send model or sketch of your invention for Free Opinion of its patentable nature. Prompt service. ‘20 years experience. Write today. ; TALBERT & TALBERT 404 TALBERT BLDG., Washington, D.C. PATENTS Secured Prompt Service. Avoid dangerous delays. d for our “Record of Invention” form and Free Book telling How to Obtain a Patent. Send sketch or model for examina- tion. Preliminary advice without charge. Flighest references. Write TODAY. J. L. Jackson & Co,. 169 Ouray Bldg.. Washington, D. C. m—— TF ee Foe —_— aa a a — a

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August, 1921 A Waste-Basket from a Cardboard Box OW a serviceable waste-basket can be made from an ordinary corrugated cardboard box in 15 or 20 minutes is illus- trated here. Dimensions have not been shown as the size will be governed entirely by the requirements and material at hand. A large and unbroken piece of cardboard is selected and cut out and folded as shown. If a single piece of sufficient size is not at hand, two pieces can be used just as well. After the card- board is cut and folded, gummed strips are pasted along the edges. The waste-bas- ket will then be ready for service. It may be sus- pended from hooks or fasten- ed with a thumb- tack. This type of waste-basket takes up little room and will fit into a much smaller space than the usual type. This waste-basket may be suspended under the desk Sandpapering Rendered Easy with This Block HE writer had a big surface to sand- paper and the use of an ordinary block of wood proved very unsatisfactory. He hit upon the idea of providing his block with handles. A hole was drilled through the block. A short length of broom-handle was then placed in the hole. Three nails were Use a block like then driven into this in sandpaper- the top of the ing block down through the han- dle. This held the handle tightly in place. With the aid of the handle considerable pressure can be brought to bear on the sur- face and the hands never slip off. To Increase the Diameter of a Pulley "TH diameter of a wooden pulley can be made larger in the following manner: Wind a length of manilla rope around its circumference in a spiral, pressing the strands close together. The end of the first turn should be nailed to the pulley, as should some point in each succeeding turn. Pull each turn of rope as tight as possible to eliminate play and subsequent stretching. The last turn should also be nailed. This treatment will increase the diameter of the pulley to double the diameter of the rope. Manila rope will increase the pul- ley’s diameter Jobs Open to You $1.75 anhr. Auto Expert $40-$50 a Wk. Chauffeur $200 a Mo. Domonstrator $225 a Mo. - Tire Expert $4,000 a Yr. - Salesman $5,000 a Yr, Garage Mgr. $10,000 a Yr. Gar. Owner and Tra ar wt Business Don’t stay a Low-pay man wishing for a good, steady income to come through lucky breaks. Make your own luck. Take a short cut to top pay right now. Come to the world-famous Rahe Auto & Tractor School. In 6 to 8 weeks Henry Rahe will fit you to pick your job in the Automotive Business—the one business that needs more men than ever and pays the biggest money. Remember, it’s the Rahe ® School Tractor & Flying 2 Million Dollars Invested—Neariy 40,000 Graduates Learn Here Easily and Quickly and learn Right. You work daily doing real jobs under Master Instructors on all types and models of real Automobiles, Trucks, Tractors and Aviation Equip- ment. You learn by the Rahe Practical Job Method of Training—the same metnod of training that has brought success and independence to nearly 40,000 Rahe Trained Men in every section of the country. You need no previous experience; no special schooling. Best of Living Conditions. Board and room always reason. able. Plenty of opportunity to earn part living expenses Whe bare here. Catalog Get my fine 84-page Catalog and Special Calls Free _ Tuition Offer fore you go to any school or shop. Both are free. Address school nearest vou, for Rahe HENRY J. RAHE, Dept. 2886 Trained Kansas City, Mo. Cincinnati, Ohio Men Than § Can Supply! Factory to to @25 on the — = New Big No. 15-225 pp. Wireless Catalog Wireless catalog mailed for 12c in stamps or coin. Any wireless amateur will tell you it isthe one catalogue to have. an ency- clopedia of information it is in- valuable. The largest and most elaborate radio catalog pub- lished. Values that cannot be duplicated elsewhere. Pit WILLIAM . DUCK = 228 Superior St OHIO satisfactory. its LY [2MonthstoPay fovea. ¥ girl can save the auall moouthly parmneate. WN ives Sites seintin ( wolous sew prices, 30 day crial offer” and Mead sic, compar — os —— ga may) Ea ——— = eTrial. have any fustrument wit h complete pent or a week’s free trial No = tion. Dean ls akan amdbaelier eibitoes aie S Outfit includes velvet lined case, self instructor, music and all accessories at factory cost. A tremendoussaving. a Convenient Monthly Payments A few cents a dog wi pay ay for instrument and outfit if you decide to keep t. Wurlitzer instruments are known al) over the world for artistic quality. Send Coupon for Beautiful New Catalog Every instrument known Illustrated with pri vee 4 L free ial peak. Lm § eden 4 No obligation. Send this coupon now. The Rudolph Wurlitzer Co -178 117 E. 4th a he tacinaats, 0.—329 8.W weet. Bi pres . Chicago St., New York, . Send me ang Jour now catalog illustrated i aor wt yeh ty fi ace a tails of Wurlitzer Complete Outfits end free | easy : payment offer. : Name ___. Addressee ——-=s0-=- oh Wurlt oe eee

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“The Best Hunch I Ever Had!” “I was feeling pretty blue. Pay-day had come around again and the raise I’d hoped for wasn’t there. It began to look as though I was to spend the rest of my life checking orders at a small salary! “T picked up a magazine. It fell open at a familiar advertisement, and a cou- pon stared me in the face. Month after month I’d been seeing that coupon, but never until that moment had I thought of it as meaning anything to me. But this time I read the advertisement twice —yes, every word. And this time I tore out the coupon! “That was the turn in the road for me. The Schools at Scranton suggested a course that would give me a real un- derstanding of our business and they worked with me every hour I had to spare. “In six months I was in charge of my division. In a year my salary had been doubled! And I’ve been advancing ever since. Today I was appointed manager of our Western office at $5,000 a year. Tearing out that coupon three years ago was the best hunch I ever had.” You, too, can have the position you want in the work you like best. No matter what your age, your occupation, your education, or your means—you can do it! Yes, you can! All we ask is the chance to prove it. Just mark and mail this coupon. It takes but a moment, but it’s the most important thing you can do today. Do it right now! —— = TEAR OUT HERE cee mee meee eee ee INTERNATIONAL CORRESPONDENCE SCHOOLS BOX 7632.B viteon obligating how ic = “s — ow I can autor the ENGINEER (ISALESMANSHIP and Rys. ADVERTISING Window T: Card and Si, Ptg. Railroad Positions ib RAINE ILLUSTRATING Practice BUSINESS MANAGEMENT Business Correspondent and Mapping 8 30 EN and ae ENGINEER Cert. Pub. Accou: TRAFFIC MANAGE conneres ENGLISH Ballder its CIVIL CIVIL SERVICE.” tS Mail Clerk Mathematics. accra A rantcuron [Bree Poultry Raising Bank Name Present Business a-t-28 pati Address Street and No. City. State Canadians Fareed - send this coupon to International Corre- apondence Schuwols Canadian, Limited, Montreal, Canada ESSO is the composition of which framemakers model the fancy scroll- work and such like on to their moldings. To make it, heat some ordinary glue in a double vessel. The regular glue-pot is the best, but two cans, one inside the other will do, the outer filled with water and kept boiling, until the glue in the inner can, mixed with a little water, is melted. ‘Into the thin glue stir whitening finely powdered until the mixture has the consistency of putty. With this composition all kinds of orna- mental relief work can be put on picture- frames, mirror-frames, panels, fancy key- holes, etc. Suppose you are going to make a picture- frame after your own design. Get a wooden frame for a base; hard wood or three-ply are the best because they are not so liable to warp. Draw or trace your pattern on the frame, mix the composition, and lay it on, keeping it warm all the time. Use a little at a time, and apply and model it with such tools as come to hand; a pen- knife, a putty-knife, an artist’s paint- brush, and wooden spatulas are all use- ful. A small lance- wood modeling - tool as shown here is very handy and. can be bought at an art shop. Keep your tools lightly oiled so that they do not stick to the gesso. If one pattern, such as a flower, is to be talent Two Gourds Furnish One Life-Preserver SUALLY ‘“‘water-wings,” the begin- ner’s swimming aid, are made of closely woven cloth, which, when soaked with water, will retain a quantity of air. Although this amount of air is sufficient to > Two gourds tied with tape will support a person of average weight in the water hold a person of ordinary weight on the surface of the water, the wings, by reason of their porosity, quickly collapse, requir- ing frequent inflation. A pair of fair sized gourds will be found to answer the purpose of water-wings ad- mirably. They require no inflation and will not become water soaked. The two gourds are simply connected by fastening the ends of a light rope or strong ribbon to each gourd. The would-be swimmer then 104 Modeling in gesso is a pleasant pastime for the amateur endowed with artistic Popular Science Monthly Gesso-Work Is Not Difficult to Learn By E. A. McCann repeated often, you may make a mold by carving it from wood or molding it in gesso (in reverse), allowing it to harden and keeping it well oiled. Place a bit of your soft gesso in the right place and press it into shape with your mold, cutting away all waste. Considerable pressure will be required. For that reason make the mold big enough to get a firm hold of it. Mark lines on the edges to show where the center is. If you are going to make a high relief, put some small screws in the wood at the highest point; they stop the gesso from breaking off if the work should get knocked about. There is no limit to the kind of design that can be selected, formal, flowers, figures, landscape or whatever your skill and fancy suggest. Furniture, such as chests of drawers, cupboards, and cabinets, is sometimes im- proved with panels and borders of this work, especially that which is enameled. The enamel should be scraped off the place you are going to deco- rate. If making a Floren- tine pattern, cut out the holes through the wood with a fretsaw before applying the gesso. For coloring use or- dinary oil-paints and gold and silver paint or leaf. Darker colors in the hollows will make the modeling stand out in stronger relief. places the rope under his or her armpits as shown. The rope or ribbon may be left long so that the gourds can be fastened to the swimmer like a life-preserver. This will give the beginner added confidence. Emergency Spokeshave from a Razor-Blade re excellent emergency spokeshave suitable for light work can be con- structed from an old safety-razor blade. First cut two plates 214 in. long by }4 in. wide, beveling both plates on one edge, and drilling each end for fixing screws. Then take a piece of wood about 9 in. long by 34 in. square, and cut out a slot about 1 in. long in the center. Now insert the razor-blade between the two prepared plates, adjust so that the cutting edge protrudes about 1/16 in., and screw into position as shown. o, ” RECESS a HANDLE SS “_ SA pF EE SS __— ee Z; VA Ya A wy" zat y = Wee y 7 RAZOR BLADE SECTION THROUGH BLADE HOLDER Another practical use for discarded safety- razor blades is illustrated in this tool —— | — aes «4. 3] en

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August, 1921 A Homemade Scraper for the Lawn F a lawn is to be leveled, this homemade scraper will be found very useful. Two large blocks of wood about 6 in. thick and 5 ft. long, are held together with two iron rods threaded at each end. Holes are drilled in the heavy wooden pieces to accommodate the rods. The rods are in- Farmers and suburbanites can make the scraper shown here with little effort serted in place and the nuts screwed down tight. Two boards are then nailed across the top and an old wagon seat is placed on them. A chain is fastened to the front end of the two bolts and a whiffle-tree is attached to it if the scraper is to be pulled by horses, but it may also be used witk a tractor.—G. BENDER. You Can Enjoy Cool Breezes without Catching Cold NE of the most delicious and certain ways to catch cold in warm weather is to sit in a cooling breeze when one is very warm. Here is a way in which to get comfort- ably and safely cool without the risk of catching cold: The necessary apparatus is an easy chair, an electric fan with the cur- rent to run it, a dish on which is a piece of ice, and ascreen. For the latter, a piece of fairly thick cardboard will do. These By using this arrangement you may enjoy a cool breeze without being in a draft should be arranged in a position well above the head of the sitter, in this instance on the top of an upright piano. The fan should be so placed as to blow the air cur- rent directly on the ice but not on a line with any person. The screen should be just back of the piece of ice at an angle of about 45 degrees so that the cool air cur- rent on striking it will be deflected toward the ceiling. This will cool the hot air that is always to be found near the ceiling of the room. The screen should be so arranged laterally that the sitter gets the benefit of the cooled air from the ice without having it blown directly upon him.—W. T. PERRY. UTOMOTIVE achievement: the world over is closely associated with, and largely dependent on, the high standard of precision made possible by BROWN & SHARPE MACHINISTS’ TOOLS The fact that they have been the choice of skilled mechanics the world over for three generations should carry an-emphatic message to you. Send for catalog No. 28, listing over a thousand tools with a million uses, 1/7, HP Motors $13.50 We offer 2000 quarter Horse Power ALTER- NATING CURRENT MOTORS of the very latest type, 110 volt, 1740 RPM, 60 Cycle single phase at $13.50 each FOB Chicago. May be attached to any light circuit in the home or power circuit in the factory. Remarkably simple in design and sturdy in construction. Fan-cooling ventilation system prevents overheating. These motors carry the Manufacturers’ ONE YEAR GUARANTEE against mechanical defects and are shipped to purchaser, ready for use in original container just as received from factory. Satisfactory performance guaran- teed, or money refunded. Single terminat—witn AT THIS EXCEEDINGLY LOW PRICE cord and plug—Non- CASH MUST ACCOMPANY ORDER. SPECIAL PRICE ON THREE OR MORE MOTORS OF $13.00 EACH. These Motors are Ideal for use in the home on washing or ironing machines, or on the bench; in the garage or machine shop or any place where one can used. They are quiet cool running, efficient and practical —with a very small chance of getting out of order. OUR SUPPLY AT THIS PRICE IS LIMITED TO THE ABOVE NUMBER be Feversed from out GET YOURS BY SENDING IN ORDER NOW. pane al a Northwestern Electric Company 410-420 So. Hoyne Ave., Chicago, Illinois

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‘Les— you'll find the same trade mark on both” RSTASLEY J SW) Wrought Steel Hardware and Carpenters’ Tools TANLEY Carpenters’ Tools are favorites with all good mechanics. Their absolute reliability lends confidence to careful hands. If you have not already col- lected a set of Stanley Carpen- ters’ Tools, start now. Buy the Stanley Hammer today. Buy each tool with the thought of permanently possessing it. Stanley wrought steel butts, hinges and other products are for sale by hardware dealers everywhere. Catalog 7H will be sent on request THE STANLEY WORKS Main Offices and Plant NEW BRITAIN, CONN. Branch Offices: New York Chicago San Francisco Los Angeles Seattle Atlanta ae a = | ) Sas a "ip Are Found Wherever Lathes Are Used Schools and Colleges use them for instruction purposes; Automobile Man- ufacturers, Makers of Small Tools (who require work of minute accuracy), Machine Shops large and small, many other industries, even hotels and de- partment stores, are using Monarch Lathes with universal satisfaction. Monarch Lathes are built with all the ‘ latest improvementsand many exclusive ees 4 features, in many sizes to meet all lathe ff i work requirements —the small shop \ handling only light work, or the largest shop or plant where the heaviest work is done. 4 Monarch Lathes are reasonably priced q i within the reach of every prospective purchaser. Write today for catalog and price list. Schools write for our special school proposition The Monarch Machine Tool Co. 116 Oak Street Sidney Ohio UILDING an electric calliope is simple, and the materials, aside from the electric motor, are quite inexpensive. The motor driving the device must be of the 110-volt style, some small fraction of a horsepower. If a perforated disk is traveling at high speed and a jet of air is directed against the perforations, a shrill whistle will be pro- duced, providing the disk is traveling fast enough and the air is at high enough pres- sure. The frequency or the pitch of the note produced will depend entirely upon the speed of the disk and the number of the holes. The disk shown here has eight rows Tunes played on this electrically driven siren can be heard a mile away of holes arranged concentrically represent- ing the notes of an octave. Eight separate nozzles are arranged so that the air flowing through each will be directed against one of the rows of holes. The rubber tubes leading to these nozzles are normally closed, but they may be opened by the set of keys ranging from C to C, as shown on the keyboard. When the motor is in rotation and compressed air is forced into the distributing tank, the vari- ous notes may be sounded by pressing the corresponding key. In this way simple music can be played. The motor used must be mounted upon a wooden block so that its axle may carry a disk large enough to accommodate the eight concentric circles of holes. The brass disk is soldered to the motor- shaft. It is necessary that this should run fairly true. It may be necessary to solder a little collar on the shaft of the motor. The 1/32-in. brass disk should be cut from a perfectly flat piece of brass. When the piece is cut out, it will be neces- sary to scratch eight concentric circles upon it with a pair of dividers. One-eighth- inch holes should be drilled around these circles. They should be about )% in. apart. After the disk is drilled, it should be fastened to the surface of a flat piece of wood with a few tacks. It should then be brought in contact with a lap grinder to take off the burrs. Each side of the disk is treated in this way. The eight little brass nozzles required should be made from \-in. brass tubing and one end should be made slightly smaller than the other. A block of wood is now cut and eight holes are drilled in this to receive the eight brass nozzles. The holes drilled should be slightly smaller than the tubes so 106 that the tubes will fit snugly. The block carrying the tubes is placed on one side of the disk as shown. It is held there by two screws that pass up from beneath. The details of the keyboard will be ascertained- by a careful study of the drawing. The details of the key seats and of the keys are also clearly shown. The key rods can be made of small brass rod. They are bent at one end and threaded at the oppo- site end to receive the key plate. After the key rod has been put in place, an expansion spring is slipped over the rod, before the key top is screwed in place. The keyboard is assembled and put in place across the base of the instrument. Eight rubber tubes similar to those used by chemists are slipped over the eight nozzles and under the keyboard. They run from the keyboard to a distributing tank. The distributing tank is really a piece of heavy brass tubing about 11% in. in diam- eter with the ends soldered in place. This is provided with eight little nozzles to which the rubber tubes are attached. The rubber tubes should fit snugly over the nozzle so that no serious leakage will occur. The distributing tank is held to the base of the instrument by two little angle pieces. The back of the tank has a larger nozzle that is made to accommodate a large hose that runs to the source of compressed air. For a supply of air the writer used a small hot-water boiler. Pressure was produced in this by an old single-cylinder gas engine reconstructed to act as a compressor. This was driven by gasoline motor, although an electric motor could have been used. Laurier Cord-Holder and -Cutter for the Home "T HOse who are frequently called upon to tie up parcels wili find the cord-holder and -eutter described here a _ valucble addition to domestic time and _ labor savers. A %-in. board, 6 in. by 10 in., forms the foundation. A cylindrical tin can of 5 in. diameter and 6 in. high is nailed to the board with small nails driven through the bottom of the can. It serves as the holder for the ball of cord. The cover on the can protects the ball from dust and dirt. The cord passes from the ball, through a small hole punched in the side of the can, to the Popular Science Monthly To Build an Electric Calliope By L. A. RAZOR BLADE. Wherever many bundles have to be tied, one of these homemade twine- holders and -cutters should be used cutter. This consists of a small block of wood 2 in. by 8 in. in size and 34 in. thick. A V-shaped cut, 7% in. deep, is made in the block as shown in the illustration and a safety-razor blade is fastened against the side of the block by screws and washers so that the edge extends \% in. or more above the bottom of the V. The cord is cut by the sharp edge of the razor.—P. P. AVERY.

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August, 1921 AN EASY WAY TO MAKE MONEY 2: ain, te uaeeniah Ge inde Get nm & Sm: '° e endent, n e tire ree fairing business.’ One man eays “I made $60.00 the first ay.’’ Others average $200 to $500 a month. Very little capital needed. Jobs plentiful. be | motorist a pos- sible customer. No experience need We teach you. SHALER Tire Repair Outfit roved Wrapped Tread Method ised by Tire Manufacturers Does as work as the big tigh priced vulcanizi outfits. boy can use it. It’s the only vulcanizer that has Automatic Heat Control, and can’t undercure or overcure a tire, Requires no watching or regulating. FREE Book — **How to Open a Tire Repair Shop.”” It tells how to make big money. Don’t delay. Write quick. C. A. SHALER CO. 2107 Fourth St. Waupun, Wisconsin _— ee ASBESTOS We are miners and shippers of Crude Asbestos in any quantity. We produce all grades at our world famous BELL ASBESTOS MINES, in Canada. We also card fibres, spin yarns, weave cloths, and make all sorts of Asbestos products, For anything you want in Asbestos turn to Keasbey & Mattison Company Dept. S-4, AMBLER, PENNA., U.S. A. Owners of the World’s Largest Asbestos Mines “Lighting Fixtures” Ready to hang. Direct from manu- facturers. Completely wired in- cluding glassware. Send for Catalogue No. 20 ERIE FIXTURE SUPPLY CO. Desk A, Erie, Pa. Cold Pipe Bending Machines pended o the World Models E&F ' Send for Catalog Standard Pipe Bends 1” to 6’ pipe, in stock for immediate delivery. AMERICAN PIPE BENDING MACHINE CO. 51 Pearl Street BOSTON, MASS. ce— y Terms. Libe Bonds taken at face value iow Wie ENGiiE "2224 Oakland, Ave. 2224 A Coil-Winding Mandrel with Removable Core HEN coils are to be wound for dyna- mos or other electrical apparatus, the little mandrel or winding jig shown will prove very useful. A wooden block is turned into a cylinder on the lathe. The diameter of this cylin- der should correspond with the internal diameter of the coil to be produced. The > cvunoer US ice ce \ ISS After the winding of the wire is com- pleted, the spool is taken off the bolt and the split mandrel removed center of the cylinder is bored out so that it will just fit over the bolt. Two end pieces are then cut. Before assembling the device the spool is split in half at an angle with a saw. When the coil is wound, this will make it possible to take the spool out without any trouble. The bolt is mounted in the chuck of the lathe while the coil is being wound.—W. C. ROYER. For Holding the Washboard in Place OUSEWIVES often find it difficult to keep the washboard properly placed in the tub when doing a light washing. The legs of the board slide on the bottom of the tub until they rest against the far edge of the bottom, which usually makes the board too low. This may be easily overcome by cutting two light wood strips 2 in. wide and 1 in. thick, long enough to fit snugly into the bottom of the tub when the legs of the board have been placed between them. Cleats on both sides hald the board at the proper angle. Keep the wash- board from slipping Two Scrub-Brushes Will Make a Foot-Wiper yo practical is this foot-wiper for use on the back porch. It can be made from two scrubbing-brushes. These are mounted, as shown, on two boards. nee SHEET-iRON The boards are held SCRUB= SCRAPER in an upright posi- tion by a base that is firmly screwed to the floor of the porch. A piece of heavy sheet iron screwed to the side piece will act as a scraper.— MATTHEW Potts. This foot-wiper will please your wife 107 Here is an instrument for counting anything from number of people at’ending a ball game to number of packages in an inventory — the Needs ; HAND TALLY With quick set-back In the public place it counts persons; in the factory or store it counts stock ; “‘in the open” it may count anything from cattle on a ranch to poles on a telephone line! Registers one for each pres- sure of the thumb-lever, counting up to 10,000, then repeating. Can be set back to zero from any figure by turning knob on night of in- strument once around. The finger ring is so located as to permit using counter in either hand. The corners of the case are rounded so as not to irritate the hand of the user, or wear the pocket if carried. The size, exclusive of finger ring, is 2 inches greatest di- ameter. Price, $5.00. The Veeder counter catalog shows Production Counters and Speed Counters, along with the Hand Tally. Ask for copy when writing. The Veeder Mfg.Co., 44 Sargeant St., Hartford, Conn.

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Screen Door Music SLAM! BANG! Every time your screen door slams it leaves its imprint on your nervous sys- tem. Slam! Bang! All summer long. Day in, day out. Don’t go through this experi- ence thissummer. Put a Sargent Noiseless Screen Door Closer on your doors and enjoy the quiet and calm of the drowsy summer evening. Use them on other doors, too. There is the coat closet in the front hall, the downstairs lava- tory door, the bathroom door, the pantry door, the kitchen door, the basement door and others. Doors equipped with Sargent Noiseless Screen Door Closers shut quickly, gently and quietly, without rebound. If not at your hardware store, write us for de- scriptive folder and the name of our nearest dealer. SARGENT & COMPANY Hardware Manufacturers 50 Water St. New Haven, Conn. Door Closer Sargent No. 20 “Reo” Cluster Metal Shingles, V-Crimp, Corru- gated, Eiending Soom. Painted or Galvanized Roof- aaa. Sioee. allboard, Paints, etc., direct to you at Rock-Bottom Factory Prices. Positively greatest offer ever made. Edwards “Reo” Metal Shingles cost less; outlast three ordinary roofs. No paintin orrepairs. Guaranteed rot, fire, rust, lightning proo: : Free Roofing Book re Get our wonderfully low prices and free samples. We sell direct to you and save you all n-between dealer’s pro for Book la. 198. “LOW PRICED GARAGES quam Lowest pricesonReady-Made fi F. R EE) Fire-Proof SteelGarages. Set Samples & | apany place. Send postal for Roofing Book Book, showing styles. THE EOWARDS MFG. Co., 848-898 Pike St., Cincinnati, 0. On Collecting and Mounting Butterflies Popular Science Monthly Patience and care insure success By E. Bade TEXT to a net, the most es- sential requisite of a buttertly-collector is collecting glasses into which the spec- imens are thrust. These are bottles having wide mouths and usually contain- ing cyanide of po- tassium, which kills the butterflies quickly and_ pain- lessly. But young trations, care being taken not to’ punc- ture them with pin- holes nor to give them an unnatural position. On extended trips it is often impossible to mount butterflies after they have been killed, therefore small rectangular pieces of newspaper are used to make paper bags as con- collectors should not be entrusted with this violent poison. Chloroform, ether, tobacco juice, or benzine are some of the less deadly poisons. The butterflies must be spread on a board and dried before they are mounted. The spreading-board consists of two thin strips of wood so placed on a base that they gently slope toward the center. This slope prevents the wings of the butterfly from sinking too much when the process has been completed. Between the two sloping strips of wood, a small rill or opening is left that is just large enough to receive the body of the insect. A very thin japanned black pin is thrust two thirds through can be made By mounting butterflies under glass and frame a handsome serving-tray tainers for them. A number of such paper bags can be placedin atin box for safe transportation. To prevent the destruc- tion of these insects by moths, a layer of camphor should be placed between each row. Preserved in this manner they will keep indefinitely. But before spreading these dried specimens, they must be made pliable and soft. To accomplish this the specimens are placed in a dish con- taining moist sand. After a few hours, if the dish has been fitted with a tightly fitting cover, the butterflies will be suffi- ciently soft so that, they can be placed on the spreading-board. Butterflies are collected for various pur- poses. It is as a the body so that the joints of the legs are neither severed nor pierced. The insect is now pinned to the spreading-board so that the base of the wings are even with bothsides of the board. Then, with paper and pins, the wings are spread as 8 decorative medium, though, that the beautiful creature: really excels. The first illustration in this article shows its possibilities as a dec- oration for a serv- ing tray, and there are articles of per- sonal adornment, such as pendants and indicated by the ac- companying _ illus- spreading-board Here the dead butterfly is shown on the brooches, for which it can be used. Butterflies too dry for spreading may be softened in a dish of moist sand tightly covered This shows how to handle and pack specimens. Fold in paper and place in a tin box An Economical Homemade Tool-Holder HERE is a tool-holder of my own make that I have successfully used in ma- chine-shops: Anybody or any shop with a milling machine can easily make them. Mill a suitable groove in the upper edge of tool-steel stock (unhardened), which should be about 1 in. to % in. thick. The groove should be of such width that the self-hard- ening steel will. fit into the groove snugly. I use 5/16-in. square self-hardening steel and 108 ~ ML An economical tool-holder set it into steel stock 14 in. by 1 in. in section. The chief value of this arrangement is SELF- that a long piece of self- HARDENING hardening steel may be used first and ground down’ more than half its length before it need be discarded. The discarded piece can then be used in other tool-holders of standard make until so short that it can no longer be used.—W. F. SCHAPHORST. wgmgu5ofi wesw Aa. 64 @ feeds iundoouo'tN®eddad co ot ="_ mam eee eet le

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August, 1921 Catch and Collect the Dew in a Pond T= principle on which the dew pond works is the complete insulation of a water-containing surface from the sur- rounding earth. To make a dew pond, dig an excavation at least 1 ft. deep and some 6 ft. square; in this place a thick layer of perfectly dry straw and over it a layer of puddled clay; on this a close layer of small In a dry, hot summer dew-ponds will add to your water supply stones. See that the clay comes well over the edge, to prevent any water reaching the straw underneath. During the day the ground round about will store up heat, and consequently water will not condense on it, but the ground under your pond is insulated from the sun’s rays and remains cool; this is aided by evaporation of moisture from the puddled clay. At night, consequently, there will be a heavy condensation of moisture from the warm air, much greater than the evapora- tion during the day; this will gradually fill the pond, even in the hottest weather. The pond should be protected from cattle, as their feet would soon ruin the clay bottom. . This plan has been used with success in high-lying waterless districts and where the water supply is far from the house or the troughs.—E. A. MCCANN. Children Will Appreciate This Parlor Trick ne esephedhan is a little parlor trick that will interest the children. A little water is placed in the bottom of a pie-tin or deep dish. A candle is placed in the center of the dish and lighted. When a tumbler is WATER GLASS PLACED RISES IN OVER CANDLE qn |_ pecs BASIN WITH WATER When you show this trick to your children, do not fail to explain the principle of it to them placed over the lighted candle, the candle will go out and part of the water in the bottom of the pan will rush up into the glass. This is caused by the candle using up the oxygen inside of the glass, which creates a partial vacuum.—J. B. MORAN. j WHEN a young fellow comes to me for — on what tools . the hardware dealer what’s new. to buy, I tell him Stosset Tools| “}’ve found that Starrett Tools are easiest to use. Every adjustment is made simple and positive. a pg a complete kit of Starrett Tools, that you’re ready for any job that == along. That’s a good feeling to have. It gives you co ae weather eye out for new Starrett T. “If you Ht want to keep on improving your » you'll need to keep on improving ra tool kit. “Round out your Starrett Tool outfit—ask “The Starrett Catalog No. 22 W is a book every mechanic should have around. Write for it now.” THE L. S. STARRETT COMPANY The World's Greatest Teslmaters Mansfacturers of Hack Saws Unexcelled ATHOL, MASS. you can earn from $1 to $2 an hour in your spare time writing show cards, Quickly and easily learned by our new simple method. No canvassing or soliciting, we teach you how, sell your work and pay you cash each week. Full particulars and booklet free. AMERICAN SHOW CARD SCHOOL 206 Ryrie Building, Yonge & Shuter Streets, Toronto, Canada ~ WANTED—A Representative in every fac- tory inthe United States. Popular Science Monthly, 225 West 39th 1 Street New York. NEW MOTORS ALL SIZES UP TO SH.-P. We Specia' ize In Small Motors & Generators PHASE AND REQUENC cK ATF ALL TIMES Lar; st €x M Or Sr tohte ‘Tapes CHAS. H. JOHNSTON. Bor KL West End, Pittsburgh,Pa 10 volts-AC, ITSO RRM. 60cS.P, e wor At a Cost of 1c a Cord! Man Saw, the first made and sold direct Pre from factory touser. Greatest labor — H-P, ond money-maker ever 106 Patent Applied For any size log at the rate of a foot a minute. Send today for Big Special Offer and Low | Poved from hes toiceor ioc ae Direct Price on the OTTAWA, the Onc- | wheelbarrow. 4-Cycle Frost Proof En- Guta: dimem eaaaert Down Trees—Saws OG By my hen fons — .. mills and other machinery. Cash or Easy Payments Shien a direct ng, no my ne runs 30 Days Trial Trial Nowsiting—no delay. ‘Let 2012 “for for fteelt aa as you use use it. 10-YEAR QUARANTER, and OO wall Sever eve it op. a on - ds in use, ‘every owner a booster. Out market, Send today for | FREE BOOK and Special Offer. OTTAWA MFG. CO., 1805 Wood St., Ottawa, Kans, w your See the OTTAWA et work on your farm once ws any other on the

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Oster No. 300 B for straight and bent pipe and nipples from \% to 2’, bolts from 7/16 to 114" Also furnished for belt drive Speedier Pipe -Threading ERE’S the production you can count on from this machine 53 seconds to thread 2-inch pipe on slow speed 20 seconds to thread 1l-inch pipe on fast speed 134 minutes to cut off 2-inch pipe on fast speed 14 minutes to cut off 1-inch pipe on fast speed 9 seconds to cut off 14-inch pipe on fast speed For prices and full details, write The OSTER Manufacturing Company 13 B-P ENGINE Sg ot Other sizes 2 to 22 H-P at proportionally low prices. ccapinoneseotdeess* ~ Prices because made in — = _ Cleveland, Ohio, U.S. A. Now only® 90 Days Trial--10 Yr. Guarantee low oe perere ATTAWA MFG. CO. 1953-A King Street oon WA, - KANSAS SPRING : - : * Folding End Hook — for measuring out of arm’s reach Ask your dealer—Send to us for Catalogue No. 12 THE [UFKIN fpULE C0. "sien" give tools no chance to get lost, mislaid or borrowed. Request FREE Catalog Union Tool Chest Co., OB ~ Bement Wg Y. alarm green feed for laying fowls in winter has always been more or less of a problem with poultry-raisers. The practice of gathering greens during the open season and drying them for winter use geet AT has been successful, ; and is recommended as a good poultry procedure. To those, however, who seek a- green ration approximating : a natural state, a == poultry silo is sug- gested for trial. It can be constructed of the same material that is used in mak- ing silos for cattle— old whisky, molasses, or vinegar barrels or hogsheads may be used. The smaller con- tainers are recommended as more con- venient where fowls are kept in pens—one barrel for each pen. The illustration shows the construction of the barrel type. For convenience, the barrel or hogshead is placed upon a stand made of heavy boards, at a height of about 12 in. from the ground. The boards com- posing the floor of the stand on which the container rests should be several inches apart so that air can circulate freely. Also a hole should be bored in the bottom of the this method Thread-Cutting Can Be Done without a Die ype saa it happens that one wants to cut a thread in a pipe, but has not a die of the right size. Under such circumstances, cut a V- shaped groove in a block of wood and TOP VIEW SS following the directions here given you may thread a pipe without a die put it in the vise so that the round of the pipe lying in it will just project above the top of the jaws. If it is along pipe, it is necessary that the far end should also be supported. On this bed lay a piece of: pipe with a thread similar to the one you want to cut; place a half-round file in the thread at exactly the same angle and drive a nail at each side of the pipe, just touching the flat side of the file. Replace this pipe with the one to be 110 BEET TOPS, CELERY TOPS, LETTUCE CABBAGE LEAVES, KALE, SPINACH, CLOVER AND GRASS (MAY BE USED Now is the time to lay in a store of green feed for the fowls in winter: try Popular Science Monthly Barrel Silo Preserves Feed for Poultry barrel to drain off excess liquid. The top or head of the barrel should be of such size as to fit in the barrel and be easily removed, and a weight should be placed upon it to pack down the con- tents. Six inches above the base of the barrel an opening may be made for ac- cess to the silage. The lid or flap of this opening should fit snugly and be secured in place by a wooden or iron button. The green feed to be stored may consist of beet tops, lettuce and cabbage leaves, celery tops, kale, . spinach, clover, and succulent grass from the lawn or roadside—any greenstuff that is fed to chickens. For convenience in feed- ing, it is advisable to chop this material fine. The silo may be filled at one time, or partly filled, and the contents added to as opportunity arises. The cross section pictured gives an idea of the contents of the barrel or hogshead, show- ing the layers of different greens. In this con- nection it may be mentioned that between these layers, litter from the barn floor— usually contaihing grain—may be used. It has a tendency to absorb superfluous juices. threaded and cut your thread with the file, keeping the flat side lightly against the nails and the pipe turning with a back- ward and forward movement so as to cut evenly. The nails, of course, should be long enough to project well above the pipe so that the file will rest against the body of the nail and not against its head.—E. A. MCCANN. Improvise a Razor-Strop from a Newspaper ro a newspaper several times into a long thin pad, and you will have a good emergency razor-strop that cost nothing. When the paper is folded to the size of a leather strop, attach a strong paper-clip to one end so that it may be hung from a nail or hook. It is used in precisely the same manner as you would use a strop made of leather. Printer’s ink provides an_ excellent stropping agent, and the steel will be found to bite after the first few sweeps of the blade. When the ink is worn off from the top layer of paper, turn the outer covers to the inside and the strop will last another month without the necessity of refold- ing.—GEORGE H. HOLDEN. A strop made from a folded newspaper will produce a keen and enecth edge on your razor aoa th ie, ae hl.

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August, 1921 Matchbox-Holder from a Block of Wood SERVICEABLE matchbox holder can be made from a block of wood 3 in. long and 1% in. square at each end. Two cuts are made as shown in the picture on the right. By these cuts a rectangular piece of wood is cut out of the original block. The complete holder, before the match- ; FLATHEAD SCREW DOOR F me Gioop BLOCK Two cuts of the saw will change the block to a convenient matchbox- holder box is put on, is shown on the right. Only the safety-match type of box can be used with this holder. The small inside tray that contains the matches is slipped out of the box-cover, and the empty cover is put on the holder, as shown on the right. The holder can be var- nished to harmonize with its surroundings. Several Methods of Stopping a Crack O mend a crack in a circular saw drill a small hole at the end of the crack, being careful that the crack does not extend beyond the hole. Do the same for a crack in a pane of glass, but get two rubber washers and with a small nut and bolt through the hole screw them on to the glass. In a piece cf nase BOLT AND WASHER CIRCULAR SAW — PANE OF GLASS CORRUGATED’ STEEL i OP, ri Several efficient methods of stopping cracks in different materials are here illustrated thin glass, a cross scratch just beyond the crack will be sufficient to prevent its running. For a crack in a piece of wood, bore a hole just beyond the crack and fill with a plug (not too tight) well glued and cut level. Box-nails are very valuable for keeping cracks drawn together or for stopping their extending. They are small, corrugated pieces of steel, sharp at one edge, and are driven across the grain. CHARACTER A business cannot survive the vicissitudes of nearly half a century, increasing steadily in breadth and strength, except upon the solid foundation of character. The character that is built into Williams’ Superior Drop-Forgings has sturdily helped to sustain the reputation of many a famous manufacturer, of automobiles, of engines, of machinery, whose aim has been to produce nothing short of the best in his particular field. Inquiries invited for forgings of character. DROP —FORGINGS en cheaper than castings —always far superior — J. H. Williams & Co. ‘‘The Drop-Forging People’’ BROOKLYN BUFFALO CHICAGO 7 Richards Street 7 Vulcan Street - 1007 W. 120th Street St. Catharines, Ontario Pilliod TOOL CASES EXCEL Machinists, Tool Makers and Carpenters find them most [EARN ENGINEERING Electrical and Mechanical Engineers receive fabu- lous salaries. Thousands wanted. 3 months to 2 yen. Practical-Technical _ traini under experts. ot a trade school but a Practical-Technical College bene ny em oe “nem. gas, ee armature % ing. xtensive orat equipment. Degrees awarded. Day and night po Tong f -. 1 any time. Don’t jud: by si le FINLAY. ENGINEERING "COLLEGE, “10s “Tndiasa tet: Kansas City, Mo. . r y wm . appearance, service and price. Booklet describing 20 styles request. The Pilliod Lamber Co. Dept. A, Swanton, Ohio SOUTH BEND LATHES For the Machine and Repair Shop 9 Lathe..ccccccvces $215.00 | 15” Lathe..........-- $450.00 11” Lathe..........+. $275.00 | 16” Lathe............ $525.00 lew 13” Lathe .........06- $365.00 | 18 Lathe............ $685.00 Run ie South Bend Lathesare made in eight sizes, 9-in. to 24-in. swing inclusive. An 80- page Established 1906 Free Catalog book for 10c Postpaid, Coin or Stamps. SOUTH BEND LATHE WORKS 433 MADISON STREET, SOUTH BEND, IND.

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The Power of Radium at Your Disposal 4 fencing years ago radium was unknown. ‘Today, thanks to con- stant laboratory work, the power of this most unusual of elements is at your dis- posal. ‘Through the medium of Undark, radium serves you safely and surely. Does Undark really contain radium? Most assuredly. It is radium combined in exactly the proper manner with zinc ulphide, which gives Undark its ability to shine continuously in the dark. Manufacturers have been quick to recognize the value of Undark. They apply it to the dials of watches and clocks, to electric push buttons, to the buckles of bed-room slippers, to house numbers, flashlights, compasses, gaso- line gauges, autometers, and many other articles which you frequently wish to see in the dark. The next time you fumble for a lighting switch, bark your shins on furniture, wonder vainly what time it is because of the dark— remember Undark. It shines in the dark. Dealers can supply you with Undarked ar- ticles For interesting little folder telling of the production of radium and the uses of Undark address RADIUM LUMINOUS MATERIAL CORPORATION 58 Pine Street New York City Factories: Orange, N. J Mines: Colorado and Utah ONDE. Rackiuzm ez mous Matezxiel Shines in the Dark

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To Manufacturers The number of manu- factured articles to which Undark will add increased usefulness is manifold. From a sales standpoint, it has many obvious ad- vantages. We gladly answer inquiries from manufacturers and, when it seems advisable, will carry on experimental work for them. Undark may be applied either at your plant, or at our own The application of Un- dark is simple. It is furnished as a powder, which is mixed with an adhesive. The paste thus formed is painted on with a brush. It adheres firmly to any surface.

112 Popular Science Monthly A Tool that Will Remove Clinched -Nails ——- nails are very hard to re- move with an ordinary claw-hammer. With little trouble an old cold chisel may be used for this purpose. A groove is ground in the chisel as shown. The chisel point is placed at the point of the nail with the point of the nail at the bottom of the groove. If the chisel is hit a good blow, it will sink into the wood, lifting the nail point at the same time. The nail point will remain in the groove and if the chisel is hit several blows, the nail will become straight.— JOSEPH B. MORAN.

For straightening clinched nails Would You Like a Pointless Letter-Opener? ) i HIS letter-opener without a point con- sists of two overlapping blades, as sho wn in the illustration, made from stiff tin or copper, and fastened to a handle.

You cannot hurt yourself with this letter-opener; it has no sharp point or edge The shapes of the blades may be varied, but the blades always overlap. In use, the lower blade is inserted be- tween the letter and the flap and the envelope cut open in the ordinary way. This tool has no points, and the sharp edges are fully protected, so that injury with one of these openers is virtually im- possible-—FRED C. DAVIs. Construct a Towel-Rack for the Kitchen ADE of a piece of stout wire and three or four 14-in. dowel-sticks, this towel-rack is inexpensive to make. One end of the wire is bent in a loop as shown in the drawing. A small hole, a little larger than the wire, is bored through each dowel- stick about 4 in from the end. The wire is then put through the holes in the sticks and another loop made in the other end of the wire. The HEAVY WIRE loops should be DRILL HOLE THROUGH \g madesmall enough

EACH DOWEL , so that a screw will fit through them. The holder is fastened to the wall or panel by screws put through the loops. The sticks can be sand- papered and painted to match the woodwork. — ARTHUR GOLDEN- BAUM. A holder for the kitchen or bath- room

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