Popular Science Monthly 1925-03: Vol 106 Iss 3

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PERIODICAL ROOM FEB 10 1925 ‘GBNERAL LIBRARY BRIIV. OF MICH, A CROSS-WORD “— Prizes offered to rood: x test your knowledge : : ; of practical words | Amazing fascination K on MONTHL 1872 of puzzles explained. iy) PUZZLE ; CONTEST—p. 38 ener Soe D Ca eS eB COE Se SA ec gauss - rey a9 TD toe EES. Bus with corkscrew drive supplants Arctic dog teams 25 CENTS is Edition Over 400,000 Copies

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ye er ial “Best proportioned hammer I ever had my hands on, in 25 years at the carpenter’s trade,” says J. R. Piercey, Conway, Ark. “The Plumb is the nicest balanced hammer any carpenter ever used,” says M. R. Warner, La Junta, Colo. Plumb Hammer cut away to show Plumb Take-up Wedge, which retightens the handle with a turn of the screw. in shape 99 ‘Just right [225 in balance says the carpenter ECAUSE carpenters helped to design the Plumb Nail Hammer, it is only natural that they should find it correct in size, shape, weight, and balance. For Plumb put into this finer tool just what you want in your hammer: —a larger face that works with you to hit the nail on the head; —a shorter neck that lets the weight come close to the head of the hammer; —claws bent more sharply, to make your nail pulling easier; —the Plumb Take-up Wedge, to keep your handle always tight; —Plumb Special Steel, tempered hard for service, tough for wear. Your hardware merchant has this hammer for you. Price, $1.30 (except in Far West and Canada). FAYETTE R. PLUMB, Inc., Philadelphia, U.S. A. on a Hammers Hatchets | Files Sledges Axes Look for THE Red Handle WITH THE Black Head (Color Combination Registered as Trade Mark, U. S. Pat. Off.) EXCLUSIVELY PLUMB eS eat ath att oenw cee read be «3

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i \ ficient power and _the mechanical - Means for applying POPULAR SCIENCE MONTHLY SUMNER N. BLOSSOM, Editor March, 1925 How Electricity May Solve the Farmer’s Problem The story of a tremendous effort to provide six million American homes with labor-saving machinery and tools By Charles H. Huntley acres of improved farm land in the United States has decreased, because of population increases, from 5.6 to -42aperson. If the American people—not to mention those of other countries who buy a part of their foodstuff from us—are to continue to be fed by American farms, either more land must be cultivated or that now utilized must be made to grow greater crops. As to that, econo- mists and agricul- tural experts long have been agreed. Generally speak- ing, the amount of land that can be used for raising crops is limited, and we are approaching the limit. On the other hand, the population is in- creasing con- tinuously. I: THE last 30 years the number of “ HE obvious solution of the problem is to obtain larger returns from what already is classed as farm land, much of which now is tilled insufficient- ly, or not tilled at all. Better methods of farming must be adopted, waste of time and labor must be lessened, and suf- Eureka, Iil. it stops. the power to the work must be provided. Not the least “Important aspect of this problem is the necessity for making good the deficiency i man power caused by the steady emi- gration from the rural districts to the cities, which in the first 20 years of this century resulted in a shift of about 11 per cent in the relative status of population between city and country, and which still continues. Now, is there anything that offers a solution of all these difficulties—any single means that will compensate for the removal of farm workers to the cities, and at the same time make pos- sible the cultivation of the additional Motor Power Grinds the Feed and Saws the Wood An electric feed grinder and wood saw in operation on the farm of Samuel Leman, A five-horsepower motor can saw enough wood in a few hours to last for weeks. The feed grinder is automatic. simply fills the hopper and the machine grinds the grain until the hopper is empty. Then Authorities estimate that men on of 100 men. The farmer power. him, farm land necessary to feed our growing population? Electricity may. Electricity would bring to the farms— actually does bring in cases where it is used—many of the conveniences of city life, the pursuit of which undoubtedly is farms equipped with such labor-saving ma- chines each are able theoretically to do the work The energy output of an average workman is rated at about a tenth of a horse- But one man easily can control the work done by a 10-horsepower machine and thus, by putting electric power to work for expand his own strength 100 times a principal reason for the emigration from the farms. Electricity supplies a possible way of enabling one man on a farm to do the work ordinarily done by several. Electricity possibly supplies a means of creating industrial ‘‘side lines” in the rural sections, which can be fol- lowed by farmers when there is no farm work. Electricity offers, in consequence, a possible way of in- creasing the farmer’s income, building up the rural villages, bringing about an expansion of social life and activities in the country dis- tricts. LECTRICITY may, in short, cause the dawn of a new era in American agriculture. The statements just made are quali- fied, for the reason that no one knows just to what extent electricity can do these things. Soon, though, that infor- mation will be avail- able, for farmers, farm engineers, elec- trical engineers, light- and power- station men, makers of farm machinery, manufacturers of electrical apparatus, and agricultural schools recently have united to at- tack the problem of farm electrification. An organization including these groups formed for the specific purpose of study- ing the matter has been organized—the Committee on the Relation of Electricity to Agriculture. It consists of representa- tives of the American Farm Bureau Federation, the National Grange, the 35 a Tr Oy ECT EEL ELL IE LOL TOE AE Fe ty ERR

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Odd Jobs Simplified With an electric soldering iron, the dairyman can keep his milk cans in perfect repair with a great saving of time and inconvenience over the old blowtorch method. Of 6,448,343 farms in the United States, according to the last census, it is estimated that about 348,000 had electric service to permit _ the use of such time-saving devices American Society of Agricultural Engineers, the National Electric Light Association, the United States Departments of the Interior, of Agriculture and of Commerce, and various manufacturers of electrical apparatus. It maintains head- quarters at Chicago, under the charge of a director, and has branches, each charged with studying the problem in its state, in several states. These branches are in Alabama, California, Iowa, Illinois, Minnesota, New Hampshire, New York, Oregon, South Dakota, Virginia, and Wisconsin. There are prospects that branches soon will be formed in other states. emer emp preparations, you may say, for so simple a matter as leading a feed wire from a transmission line to a farm. And, too, you may wonder why farms, like factories, were not electrified long ago. The reasons are not hard to find. When electric drive for machinery first entered the industrial field, it found power in use in large quantities in mills and factories. Hence it was a question simply of supplanting steam or water power; of substituting a motor for the engine or water wheel. Moreover—and this is an extremely important point— the factories were centralized in com- munities. Electric power could be dis- tributed to a number of them within a short distance from the central station where it was generated. Since it costs Just Hatched This electric incubator hatches 250 eggs at a time. In recent experiments at Red Wing, Minn., a hatch of 77 per cent was ob- tained from an_ electric incubator, as compared with 55 per cent from an oil incubator operated by the same _ poultryman States, most of them on farms. In addition, an enormous total horsepower is repre- sented by tractors, gasoline engines, wind- mills, and other de- vices of the kind. Not- withstanding all this, the use of power is widely scattered and POPULAR SCIENCE MONTHLY factory workers, March, 1925 more than twice as much to distri- the individual farm does not, with the bute electric power as to generate present farm application of electricity it, the expense of supplying it in- offer a large load. . creases with the length of the However, in the aggregate, there is 9 distributing system. Also, follow- big field for electricity in agriculture ing the closing of the mills for Farming is the country’s basic industry, the day, came another “load” for It represents an investment of more than the generators—the lighting of $77,924,000,000 in land, buildings, live the innumerable homes of the — stock, implements and machinery, and which meant it produced in 1923, the last year for that the generating machinery which figures are available, wealth could be kept continuously busy amounting to $16,064,600,000. Also it and hence profitable. But in the case of the farm, the livelihood of 29.9 per cent of the country’s situatiom was entirely different. people. ir The individual farm is, even yet, : ; in cases where electricity is used. * IS this big field that engineers and at all, a.small user of electric * power. And ‘whereas there may power-distribution lines. Practical work be a dozen factories within a few already has begun. State branches, as [ city blocks of a central station, have said, have been organized. Unaer the average distribution of farms the auspices of the Minnesota Commit- is only a few to the mile. tee, for example,. an experimental line It is true that the aggregate has been constructed near Red Wing, amount of power used by the Minn., that promises to be one of the farming industry is huge. The most important steps ever taken in the last census showed more than _ direction of farm electrification—one that 20,000,000 horses in the United may bring untold benefits to American is an industry that directly furnishes the economists have set out to open up to farmers. This line is only 6.3 miles long. There are 19 possible customers living along it, not all of whom yet have availed them- selves of the opportunity to have electric service. But it is a laboratory experiment in the use of electricity on the farm that will give data of immense importance, hitherto lacking. The various devices used are equipped with meters and records of the amount of current consumed by the individual machines are taken to determine the cost of operation. The time used in doing specified items of farm work with and without the use of electricity is noted. Other information of a similar nature is being obtained. This experiment is being carried on under the direction of the College _of Agriculture of the University Electricity frees the farmer’s wife from rural bondage. This dish-washing machine is but one of a number of electrical devices that have brought to a South Dakota farmhouse every convenience of the up-to-date city apartment

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at POPULAR SCIENCE MONTHLY oo Wher of Minnesota. Current was turned on the line about a year ago, and the work will be continued for three years. BOUT 40 manufacturers of electric motors and appliances, farm ma- chinery and barn equipment have sup- plied the apparatus needed for the experiment. This equipment is loaned to the farmers for three years. If, at the end of that time, they do not care to keep it, they can return it to the manu- facturers without expense. If they wish to retain it, they may buy it at a price agreed upon when the installa- tion was made. The Red Wing experiment might be described in detail, but it seems unnecessary here. A few specific accomplishments, however, may be mentioned as showing what electrical power already has done in that section. It has been found that on one farm about four tons of feed are ground a week. Corn, oats, and barley are handled five times, and three men, a team and a wagon are employed in the process. By the application of electricity it is hoped the work may be done automatically. One family was about to leave the farm when the experi- ment was begun. Now they have decided to stay. The wife is getting along without the which he always craved—leisure. Electricity Makes Up for the Shortage of Man Power A 15-horsepower motor cutting silage on the farm of Fred C. Crane near Dalton, Mass. Notice that only two men are employed to perform work that ordinarily requires a large crew. It is in making up for the alarming emigration of man power from country to city that electricity offers the most promising solution of the farm problem. In the 20 years from 1900 was in need of repairs, had almost decided to move to town rather than undergo the expense of making necessary alterations. Since the installation of electric power, however, he has completely renovated and painted’ the house and has made up How the Farmer Saves Repair Bills ever-troublesome hired-girl ques- With electric power tools at hand, the farmer no longer need waste from light- and power-station distribution lines is estimated at 166,000. In addition, the number of individual farm power Another man, whose house and light installations is somewhere between 200,000 and 400,000 (Continued on page 160) to 1920, the shift of population from rural to urban districts was about 11 per cent. In 1900, 40.5 per cent of the population of the United States lived in communities of 2500 or more. Ten years later this propor- tion had increased to 45.8 per cent, and in 1920 to 51.4. per cent. Now motor power is proving a substitute for human labor lost to the farms his mind to remain on the farm perma- nently. For electricity has provided him with every comfort he might expect to find in the city—hot water for his bath, heat for his cooking and light for his home, as well as water for his stock and power for his machinery, lessen- ing his labors. ° Women, too, are being freed by electricity from rural bond- age. One young woman told an investigator that all her washing and ironing is done now in a day instead of requiring a day and a half of her time and half a day of her father’s. VEN unborn chicks in the shell are touched to greater endeavors by the magic wand of electricity. Two incubators side by side, with eggs from the same hen, and operated by the same experienced poultryman, gave interesting results. A hatch of 55 per cent was ob- tained from the oil-operated incubator, and 77 per cent from the one heated by electricity. The operator reported, too, that more cripples came from the oil- operated machine. Experimental work similar to that at Red Wing is in progress in a dozen or more other places, notably in Alabama. From all this it should not be assumed that electricity is not . : : time and money going to town for repairs on his auto and his farm ” tion staring her in the face. The machinery. This farmer is boring holes in a fender with an electric being used on farms to any con- husband for the first time in his drill, a tool that has innumerable uses about the farm. The siderable extent. It is being life is indulging in a luxury number of farms on which power for such tools now is available _ successfully employed on a num- ber of them.

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POPULAR SCIENCE MONTHLY March, 1925

x Cross-Word Puzzles 7s i) ° e e 4 Columbia University psychologists explain the fad’s great fascination—A new test of your acquaintance with science (CO tists game sets have found By H. E. Jones, Ph.D., est in the puzzles tended to score highest their way to bargain counters, : and in the intelligence tests also. In fact, the and the strains of ‘‘Bananas” no relationship between the two was so high longer filter in through your radio set; Prescott Lecky, M.A. that we may regard the cross-word puz- but a new frenzy is upon us, claiming zles as fairly good intelligence tests in more—victims, shall we say?—than any resourcefulness, readiness to try new themselves. other fad of recent memory. Perhaps “leads,” quickness in perceiving and But entirely aside from the question of it has already overwhelmed you, for few _ criticizing his own’ errors, shrewdness in their actual human value, just what is the have escaped the Cross-Word Puzzle Bug. making guesses when subtle clues are’ secret of the amazing, almost hypnotic From dawn until midnight people every- given that stand the confirmed puzzle _ lure of these black and white squares? where are rushing about in distracted victim in such good stead. Are we, then, The Chinese game knew no such vogue; search for seven-letter words meaning to say that general intelligence is a neither did the “every-day-in-every- “three-toed,” and two- way” formula of Coué, letter words meaning ‘“‘ex- Other fads—diabolo, burnt- ists.” Millions of people wood engraving, pingpong these days seek no further Can You Solve It? and crokinole, for example, happinessthan thatsupplied ke were swept along on the by a cross-word puzzle and A Prize Contest Announcement crest of a concerted wave of a dictionary. , : ‘ enthusiasm for a year or so, The University of Ken- H== is a chance to indulge in the latest fad, to test your only to collapse at last and owledge of general science and the mechanical arts and : tucky puts cross-word possibly to win a cash prize. to disappear. But the wave puzzles in the college cur- On the opposite page is a cross-word puzzle. Almost every that carries the cross-word riculum. constitute a remarkable educational force? number of correct words tallied for each 40. Are they, as some hold, a sort of short cut _ student. In this way a “cross-word AND publicity did the rest. The cross- to the acquisition of general information score’ was obtained. Then the class was word puzzle soon found its way into 42. of a useful sort? given an intelligence test of the type the news and editorial columns, into comic $3. A moron would be as helpless with a familiar in school and college work. strips, vaudeville acts and the radio. 45, cross-word puzzle as with a game of chess. What was the result? Well, it was From eye to eye and ear to ear the story 47. He possesses only to a limited degree the found that the students who scored high- (Continued on page 164) ~

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wwe? ast he gh . of the tic es? ue; ry- u é, nt- ong ple, the 2 of and ave ord her r of oe ms ally zzle t do the new The nind hem irst, oub- Ave- ame the rame dogs it is puz- mm a ‘ork. re or and 3 not m a saw TOSS- omic adio. story POPULAR SCIENCE MONTHLY mal group - Small, bushy herb . Granular rock ma- terial 45. Engineering de- gree (abbr.) - Instrument widely used in telegraphy Effective receiving 68. 69. 71, employed in geol- ogy A shoal Points of the cres- cent moon Amorphous _ sub- stance derived from ancient vege- tation 94, 95. 96. self-contained pow- er and the like Lettering on archi- tectural drawing Output of electrical power station (pl.) Pertaining to. an important source of light and heat 16. Outlay . 18. Extent of a surface 20. Used in tuning a radio receivet 21. Storage places for fuel 2. Clanging sound 4. Unit of length (Spanish) 59. 60. 61. 63. White protoplasm found floating in the blood (comb. form) Extensive Spasmodic twitch- ing of muscles. Metallic dross 6 8 } ? 7 as 13 14 15 16 f ‘? 7 18 19 20 2) ‘ 22 : i i 23 24 25 26 i 27 28 29 30 3) 32 33 y g 7 H } ) | LL 34 35 6 37 38 *i j 40 417 42 43 - 44/7 45 . [46 47 48 49 50 5) - ‘ } ) \ 52 , ’ 33 ca ss /\ \ '5s6 57 58 i oo ” 60 ~ a ol 62 637 G4 GS 66 7: % —_ / : {4 C | Ly 68 - 69 sf ; F 70 ‘ 71 72 L / \ Thy 75 76 / 77 lL aa \ i / } ; a . ( | | A} j se { / f\/ 79 80 / a 8} 82” 83 { , c 2 SSG \ rf a 7 184 85° z , \ 86 87 88 / 4 ? BE Ty MW \¢ : A 7 { 3 J 390 / 9} x 2. 93 / 2 4 4 a T 35 96 HORIZONTAL VERTICAL + Machine tool distance of a 73. Architectural 1. A kind of light 26. Abrasive 65. Symbol used in . eeeting _ device radio set drawing seen at night 27. Type of drill shank — of a seal on used in optics 51, Exceedingly rapid 74. Membranous 2. Wasting disease 28. Graal ate : documents . rod surface of a rae salad pouch (abbr.) 30. a oe Beato 40 — a ‘ tions (abbr. a ee : : (comb. form . Fastening device J : 75. Cover 3. Implement used in 33. Source of electric 6g. p ris R . Unit of work 52. Luminous circle 77. Strap for control- masonry pte td - Passage of magnet 16, Solid figure 53. Symbol of quality ling an animal 4. Wasp of the Sco- 35. Shel d sid pec? > 17, Component of _ta- in technical mer- 79, Projection in a liidae family ws etered side = 69, Vehicles ble salt (symbol) chandise * machine 6. Concerning (naut.) 70. Position 19, Stamped 54, Very (scientific : : 37. Precious element .,° - 21. Hard, porousstruc- prefix) 80. Meteorological 7. Important metal- (symbol) 72, Carnivorous mam- ture 55. Descending axis of instrument lic element 38. Bend downward mal inhabiting Af- . Geometrical ratio a plant 83. Extinct bird 8. Relative weight 39. Sueietal ‘ eee and Asia 23. Curve 56. Element of plat- 84. Common applica- (abbr.) + MECH CHT 73. Small form of veg- a mevent oe group (sym- tion of the wedge 9. Assortment of type 41, Vigorous " — a é . Insect ol) 85. Devices to convert Fee Ae eae: ; — 74. Coarse hulled corn . To enlarge a hol- 57. Adjustable instru- rotary into recip- 10. Chemical suffix dis- ie 2 ee ee 76. Ten low ment for measur- rocating motion tinguishing me m- 44. Rearward (naut.) ° ’ . Radio amateur ing angles 86. Reverberation bers of paraffin se- 46. Fruit-bearing part 78. Lowest possible Insect 60. Artery 88. Element found in ries of cereal plant 80 Reeia toe ania . One who has com- 62. Rare element mineral cerite 11, Element named for 48. Ferment (chem. . Antidote for act pleted a_ college whose name means (symbol) goddess of harvest suffix) Millon = course (abbr.) “earthy” (symbol) 89. Abrading instru- (symbol) 50. Containing nitro- 81. Million , » Indigo plant 63. Commonest form ment 12. Tested * gen 82, Genus of poison- Tarn ammal =» og DFBEOFY mo- 90, Laboratory aye 14. Prefix denoting re- St. Becompose ous plants . Suffix denoting 64. Tree ments j pe re le me- _ 58. Science of insects pes ee a members of anani- 66. Suffix frequently 92. Prefix denoting oe ag > (abbr.) 87. Pertaining to the ear (comb. form) . 90° angle, (abbr.) . Poisonous gas (symbol) . Variation of im- portant scientific degree (abbr.) . Termination denot- ing an oil (chem.) Sooner parmeroennionae? > reste ses ee

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POPULAR SCIENCE MONTHLY - PROPOSED U.S.DIRIGIBLE AS SHE MAY APPEAR WHEN COMPLETED LENGTH OVER ALL, 785° GAS BAGS OF GOLDBEATER'S SKIN ——~ DIAMETER 122 > — > Panels colts > POWER Cite Pa cans These drawings give an idea of how the U. S. Navy’s proposed super-dirigible may appear when completed. They show her gigantic size compared with the world’s greatest air- ships; the cross-section construction of her envelope; how she may be anchored to the mooring-mast at Lakehurst, N. J., and her spacious accommodations for the passengers U. S. Plans the Greatest Airship of All the Los Angeles and the Shenan- doah, and even the two great dirigibles ordered by Great Britain, is an air-liner proposed recently by United States naval experts. It would be by far the largest airship in the world. With a capacity of 6,000,000 cubic feet, nearly three times that of either of the American dirigibles and 1,000,000 cubic feet more than the British ones, it could be used for regular transatlantic trips. It would carry 80 passengers on a voyage and at least 32 tons of mail and freight. Counting on 40 round trips a year be- tween New York and London, it is esti- mated that the leviathan would make a net yearly profit for the United States | D eazy the giant proportions of Government of approximately $5,000,000. In design the air-liner differs radically in several ways from any others previously built. The R-100 and the R-101, the two ships that the British are planning for passenger service between England and India in 1927, are to use hydrogen in their gas bags. But while hydrogen has greater lifting capacity, United States officials favor helium on account of its safety. By using hydrogen in conjunction with helium, the advantages of both may be retained, and this combination is in- cluded in plans for the proposed American dirigible. Hydrogen would be used for the inner gas space, surrounded by a layer of helium that would act as a pro- tector from fire. The cabin, which for passenger servicé would contain luxuries comparable to those of ocean liners, would extend nearly half the length of the ship. Ordinarily the ship would operate from mooring-masts. The one at Lakehurst, N. J., which is 167 feet high, could be used, but others of greater height would have to be erected. For repairs, a shed of huge dimensions would be necessary. A dirigible with 10,000,000 cubic feet capacity, according to experts, would be- capable of making non-stop flights around the world. Rear-Admiral William A. Moffett, Chief of the Bureau of Naval Aeronautics, estimates the cost of the proposed air- liner at $6,000,000.

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ay her rvice e to early from 1urst, ld be vould ed of e feet 1d be’ round Chief uties, j aire POPULAR SCIENCE MONTHLY \ : Be ' ‘ * at revi’ — ‘ " a y \ \ \ ‘1 \\ wi > ee ot . Ye oe 8 4 | , ee : a s Ltd Remarkable picture of the spillway of the great Wilson Dam discharging a recent flood of the Tennessee River. Fifty-eight steel gates, each 38 feet long and 18 feet high, mounted between the sections of the dam, control the flow of water. The river has a fall of 100 feet in 40 miles What Muscle Shoals Really Means How a Stupendous Engineering Project Is Harnessing Nature By James Knox O THE average person the great Muscle’ Shoals power-development proj- ect in northwestern Ala- bama probably represents another instance of inabil- ity to see the forest for the trees. Legislative and po- litical complexities that have surrounded this great project virtually since its inception have contrived to obseure the fact that, although it is one of the vastest engineering under- takings ever prosecuted by man, its purpose and intent are intrinsically simple and hence readily understandable. Muscle Shoals is a wide, shallow section of the Tennessee River, extend- ing from Florence, Ala., about 260 miles from the mouth of the river 40 miles upstream. In these shoals the depth of water varies between five feet at high tide and one foot at low, making the river un- navigable, of course. Through the: 40 miles of the shoals the river falls 100 feet, and the banks are high, thus suggesting water-power possibilities. For 100 years or more inhabitants of the country have dreamed of making this section of the river navigable, for the ‘Tennessee flows through a country rich © General Electric Company A striking view of the $51,000,000 Wilson Dam at Muscle Shoals, as sketched by the famous American architectural and landscape artist, Vernon Howe Bailey. The magnitude of this project is exceeded only by the Panama Canal in coal, minerals, and agricultural re- sources. In 1832 the State of Alabama constructed a canal about the shoals, which was partially reconstructed 35 years ago after being in disuse for years. Meanwhile almost constantly the shoals were studied to determine a method of development that would at one time open the river to naviga- tion and supply power for the industrial growth of the country. T REMAINED for the war, however, to make the development of Mus- cle Shoals an actuality. Under the National De- fense Act construction was begun by the Engineer Corps of the U. S. Army early in 1918 on a large plant near Muscle Shoals for the manufacture of nitrates by an atmospheric fixation process. The nitrates were to be used in the manufacture of ex- plosives during war and for making fertilizer in peace time. To furnish power for this work, construction of a large steam plant was begun, and later in the same year a water-power project was instituted. This latter includes the construction of three dams and two power houses, the dams to be equipped with locks for navigation. That, from an engineering standpoint, is virtually all there is to the Muscle Shoals development—the construction of dams for power and navigation, and the con- struction of hydroelectric plants that will convert the water power into electric Sew R OT — 1 AS NiO T AE LE Oe

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chi Nt le } ic. ; 4 #3 ig <a - é on ~ mMIMINITITYYTY YY YY WOUUTETEAE EE ADE UN} HI C p4 ee ue ‘4 NOR any Vy. - = “Se Lh] 4 A Giant Generator Owing to the uneven flow of the Tennessee, Wilson Dam cannot supply power throughout the year. This necessitated an auxiliary steam plant, one of whose huge turbine generators is POPULAR SCIENCE MONTHLY Zoi) HE ee ir \ ine aman EAN ee ep Uy pi In many fp Beg SEO. “ee a Wilson Dam is the ay jae eS ae ie a ae . most remarkable a (f s

fh; A Mile of Masonry

structure of its aay : kind ever reared by ‘ man, a fact that is admirably by this view of the complex details of construction of the power-house sec. tion, taken the do from — The dam js almost a mile and its re Tanges from 95 to 134 feet, It covers 20 acres, and, when completed, it wil] contain 36,500,000 cubic feet of mas. sive Masonry

shown here. The maximum capa- city of dam and steam plant will be 260,000 horse- power Airplane view of the workmen’s village at U_ S. Nitrate Plant No. 1, containing modern houses and paved streets

yt Se c BOWLING GREEN current for use in the making of nitrates for explosives and fer tilizer and possibly for general industrial purposes also. K Y The dams are known respectively as No. 1, No. 2, and No.3 Dam No. 1 is to be exclusively a navigation dam. Construction has not yet been begun on this project. Dam No. 2 is the famous -4 Wilson Dam, one of the greatest pieces of construction @ver

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ap NASHVILLE rn undertaken. When this dam is completed, probably next No vember, its construction will have cost about $51,000,000, and KNOXVILLE it will make available, engineers estimate, a maximum hore rE power of 260,000, of which 200,000 will be available continuously. The variation in output will be due to the irregular flow of "@ the Tenneessee River, which ranges between 7350 and 500,00 poe cubic feet a second. This dam stands about three miles from duarranodcn the proposed site of Dam No. 1. Twenty miles upstream from Wilson Dam is the site of pte posed Dam No. 3, which will be constructed both for power and navigation. This dam, to cost about $25,000,000, is expected to develop 250,000 horsepower. i GA. The total possible power development at Muscle Shoals is

its entire length from

the Ohio River % Lanta) estimated at about 6,500,000, or almost the total power of Niag- SRMINGHAM ara Falls. That power, however, would be available only fot \ short periods, on account of the uneven flow of the river. bs ; ’ ‘ estimated that Dams 2 and 3 will give not more % Map showing location of Muscle Shoals. Completion of all the pro- $50,000 horsepower—an d that for only 20 per cent of the time. posed construction will make the Tenneessee River navigable through at Paducah, Ky. Two nitrate plants also have been constructed as part of the

dam navi oth

compris is caller plant, a The t develop: pleted, y 3 and th about $3 Vario Muscle Miles, Hooker, erty, bu these of but the be fort] develop)

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| No. 3. truction on ever ext No- 00, and 1 horse- ruously. flow of 500,000 les from . of pro- wer and Shoals is of Niag- only for er. Its re that r the time. rt of the March, 1925 Converts River into Lake An admirable bird's-eye view of the entire Wilson Dam construction is shown at the right. The dam will back up the Tennessee River for 18 miles, creat- an artificial lake averaging three-quarters of a mile in width. In addition to sup- plying power, the dam contains two navigation locks. When the two other proposed dams of the Muscle Shoals develop- ment are com- pleted, the river will be made navi- gable through 85 miles of shoal water at times. One of the valves in the sluice section of the Wilson Dam. Note the size of the man compared with the opening Muscle Shoals development. Nitrate Plant No. 1, built at Sheffield, Ala., about five miles from Muscle Shoals, was com- pleted at a cost of $13,000,000 as an experimental plant to determine the efficacy of the Haber process of nitrogen fixation. Induded in this development are a 5000-kilowatt steam plant and a village of 1900 acres. Nitrate Plant No. 2 is near Wilson Dam. It is virtually com- pleted, and is said to be the largest in the world. This plant comprises six plants essential to the fixation of nitrogen by what 8 called the “cyanamide process,” a 60,000-kilowatt steam plant, and a town of 2300 acres. The total expenditure of the government for Muscle Shoals development when Wilson Dam and its power plant are com- pleted, will be $131,300,000. The completion of Dams Nos. 1 and 3and the power house at the latter probably will raise the cost to about $165,000,000. Various offers have been made to the government for the Muscle Shoals property, which comprises about seven square miles, Henry Ford, the Associated Power Companies, Elon H. Hooker, and the Union Carbide Company have bid for the prop- erty, but Congress has yet to make definite disposal of any of these offers. The Ford offer was withdrawn some months ago, but the others are still awaiting congressional action, which may be forthcoming before this summary of the Muscle Shoals development is printed, POPULAR SCIENCE MONTHLY The Steam Plant At right is shown the steam plant that will supply auxiliary power for the Wilson Dam. On account of the varia- bility of the river’s flow the dam may furnish only 90,000 horsepower The steam plant, however, will in- sure an average output of 200,000 horsepower throughout the year a NITRATE PLANT (PFT U.S. NITRATE PLANT NO.1 ei. MUSCLE SHOALS | This map shows location of work completed at Muscle Shoals. Pro- posed Dam No. 3 will be about 18 miles upstream from Wilson Dam. Proposed Dam No. 1 will be exclusively a navigation project go ere MS

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By W. S. Taylor q ACKING only some minor interior work to complete it, the new two- story residence of John C. Ketcham, Glen Head, N. Y., bank employee, stands ee John C. Ketcham ae laying the brick foundation for his Leng Island home. “I emerged from this job a fully ap- prenticed bricklayer,” he asserts ee to the credit of his own handi- craft. Even drawing the blueprints himself, he made a personal job of every detail of actual construction, permitting no other hand to touch a tool. He built the house in 18 months, averag- ing about two hours a day at his work. That is equivalent to 137 eight-hour days. Mr. Ketcham’s singular achievement is remarkable, not only because he did all comes from a sedentary occupation and was without experience in any of the skilled trades so important in modern building. Working every night by powerful electric lamps led from a special circuit, and every Saturday afternoon, rain or shine, he went forward with his building, while neighbors marveled at his deter- mination. But Mr. Ketcham maintains that he worked solely for the pleasure it gave him, that he found the night air in- vigorating and the exercise wholesome, and that he is a healthier man for it. “Tt is positively sport,’”’ Mr. Ketcham the work himself, but also because he: POPULAR SCIENCE MONTHLY Single Handed He Built His Own Flouse A Story of an Unusual and Profitable Hobby told me. “I have a sloop over in Long Island Sound; it used to be my hobby, but I haven’t been near it in 18 months, that is, since I have been at this building. I really regret that the work is so nearly finished, because I’m afraid I’ll have a hard time finding another recreation so completely satisfying as this has been. **My object in building the house my- self was not one of profit. However, it is very gratifying to find that I have re- duced the cost of my house more than half. I have always wanted to put up a house all by myself, nail by nail, and strictly in accordance with my ideas. Asa boy in the country, I acquired a slight knowledge of the use of tools. This came back to me readily in spite of years in a profession so alien to it. However, I did encounter considerable perplexity at times, for I had never done any actual carpentry work, brick- laying, lathing, and so forth. My plans called for founda- tions and a chimney requiring more than 15,000 brick, laid in troweled cement courses. The mo- ment I got this work under way, I real- ized that my inex- perience was a far greater handicap than at first I had supposed. I had to make considerably more than the usual adjustments of plumb lines to aves or bulge. I might add here, that Ie from the job a fully apprenticed: brick. layer. “‘T used plumb lines in leveling the joists, too, and in framing the poreh. 4 greatest trouble in the latter was to ge the right pitch and slope. “No part of the work seemed to demani excessive physical exertion, except ‘the rafters. These are of Western fir, ang heavy for one man to handle that to contrive a derrick in order to “7 e up unaided. ae “Friends assured me that [I never complete the job. At first ¢ decried my lack of experience; ed switched to forebodings of resentment organized labor. This guess was Wr for often a master builder or a j man dropped in to offer suggestiong/= “‘Now that the house stands an accom. plished fact, it is a great satisfaction to have upset the early, easy-minded o viction of my skeptical friends. And th satisfaction is the more Cor plete in view of the fact tha now those doubters fhe selves are planning to my example in the “~~ use of the spirit This is the attractive home built by Mr. Ketcham without a single level and frequent helper. Professional builders pronounce it a perfect piece of

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asf Fis = ot wt PROPOSED BB-STORY * SKYSCRAPE aa iL. _ 4 WOOLWORTH gi "Tt BUILDING é ; aneet - 2, * ed sd ded tng # « i he é Hs SINGER POPULAR SCIENCE MONTHLY * F - % Pi sayy, diag. » eT ig EO wes =F BUILDING - LOLA “AST Rivep ee 4 BROOKLYN - BRIDGE 7 4 | a * te we Fe we nea. " nw | , ~ | ». BROOKLYN | 4 xl rs . , s &. * BATTERY PARK A eet innnnereanill ee Aettanes "ite - ‘die Meme tat a A Oy nas Fs: HE Doan seeing A be, Propose 88-Story Skyscraper for New York would tower above the Wool- worth Building, now tallest in the world, and other skyscrapers of New ork, has been visualized here by our artist, using an extraordinary air view of lower Manhattan as a basis of comparison. Sueh a building, rising 33 stories above the Woolworth tower, shown just to the left of it, now is being discussed by ‘minent architects and engineers as a Possibility of the future. An interesting Phase of this discussion concerns the Problematical engineering difficulties to encountered in going so high above the H*: an 88-story office building loftiest structure so far attempted byman. The new building would be about 1250 feet high, or nearly a quarter of a mile, assuming that the floors would be similar in height to those of the Woolworth Building. This would make it 250 feet higher than the Eiffel Tower in Paris, the highest structure of any kind in the world, and about 460 feet higher than the Woolworth Building. Engineers point out that exhaustive tests would have to be made to determine not only the usual stresses and strains of such a structure, but also the strain caused by resistance to the wind. When the Woolworth Building was finished, tests made in an 80-mile gale to deter- mine what effect wind pressure had on it, showed that the building was unaffected by the strain. But: just how much stronger a building half again as high would have to be to withstand the pres- sure of a hurricane is one of the problems that would have to be worked out carefully. To this end a detailed study of the re- actions of New York skyscrapers during heavy blows is reported to be in progress. The findings may determine whether a mammoth building such as that pictured above will prove practical.

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Now Comes the Air Taxi Hundreds of people are using flying cabs to carry them to business and on pleasure trips—Remarkable new developments in luxurious passenger planes and By Robert E. Martin SHORT time ago a man called up an aviation company on Long Island, N. Y., and said his brother A POPULAR SCIENCE MONTHLY March, 1935 sky ‘‘flivvers’’—A forecast of future travel five minutes later a car is at your door to whisk you to the landing-field. There a plane already is out. Its whirring pro- pellers hum a welcome at your approach. Three steps up, a gentle lifting thrill, and you are winging toward was dying in Chicago. He inquired if he could hire a plane to take him to Chicago Sky Riders Travel in Luxury Passengers travel in delightful luxury in the latest American type of aeromarine-metal flying boat recently completed for service on the Atlantic coast. This interior view of the cabin shows how Six passengers are accommodated, in comfortable “parlor car” chairs. Each chair is beside a win- dow through which the passengers can view the scenery far below them as the plane speeds along at once. He could; and he reached his brother’s bedside seven’ hours later. The air taxicab made this possible. In an emergency the airplane taxicab is indis- pensable. To reach a dying parent, close a business deal in a distant city, send a salesman, -eatch a ship that has left a dock, or to go a dis- tance in the shortest pos- sible time, nothing beats the speeding airplane. And the airplane today is at the disposal of everybody. Few people realize that searcely a city of im- portance in the world today is with- out its commercial airdrome. The system of usage at last is becoming generally known. You call the airplane company; your destination. The airfaziat last! **Tnevitable!’’ 10 years ago, when some one suggested No doubt he had in mind the terrific acceleration of all living in cried Wilbur Wright Day and Night Service *¢ Re “ie 3 Day and night fiying have become a regular feature of a new passenger airplane route be tween London and Copenhagen. Above is one of the Dornier all-metal flying boats in the night service. It carries 10 passengers im the scheduled service between the two capitals Carries Passengers and Mail The eight-vassenger Fokker plane shown below is in daily service between Amsterdam and Lon- don and Amsterdam and Paris. It also is used to carry the Royal Dutch Air Mail. Pilot and navigator ride in front in an outside cockpit Ten-passenger plane of all-metal construction developed by Claude Dornier, a Zeppelin engineer. All wood and fabric has been replaced by duralumin this century of wonder —radio compressing the globe to a miniature d what it was; daily ait mail closely linking cities; world fliers laugh ing longitude out d countenance. The motor-car ha been a wonder in it day, an agency for pas time and a means for hurry to and fro. Now traffic congestion has almost killed its ue fulnesses. Motor path ways have com land taxi’s last Now they, too, # jammed. To one not in close touch with the situation, the figures showing the extent to which this congestion is bell relieved by sky transportation is startlim will be will clo spects land ta: Bay, @ section task th: N F taki men re transpo the Aut city, to on the it took they ni minutes In ti

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195 : March, 1925 American company operates 46 air in its district. Another with 11 janes has terminals at New York, Key Wi est, Miami, Havana, Detroit and Cleveland. London dwarfs all with 16 distinct and independent air lines to all of Europe. : ‘ But London may lose this prestige be- fore long. Chicago’ and Dayton pro- moters are organizing a Yellow Air Taxicab Company to build aerial cabs and operate them between Chicago, Cleveland, Detroit, Boston, New York, and Washington, maintaining regular schedules, as well as special trips, and with connections at all points. The cabs One . POPULAR SCIENCE MONTHLY sengers at 600,000. Out in the Pacific Northwest some 2500 persons traveled in hired airplanes last year. Business trips from Peoria and Bloomfield, IIl., were made into Chicago and St. Louis in air taxis by 1500 people during the same time. The chief value of these statistics is that they make a picture. They show how rapidly this new vehicle has eome into almost universal use. Who uses the air taxi now? Why &) hi. j Eo Mas = oT oe SD) 450-11.P OH, PASSENGER BIPLANE AWNING FLAP HP NAPIER LION IZ CYL. ENGINE, 900 t NGINE, 87. LBS. FLAP IN NORMAL PosiTION — : PRESSED TO DECREASE (1Wo Positions) | ~/ BLERIOTS 25-.R MONOPLANE 20-30-H.P CHERUB 2-CYL. Fit in Garage A tfecent elimination flying contest in England for planes that could pass through a 10-foot gateway produced a number of amazing aerial “flivvers,’’ some of them small enough to be housed in a back- yerd garage. Among them was the ‘‘Wee Bee’”’ (below), a 20- horsepower monoplane with folding wings. The diagram shows this machine beside a 450-horsepower plassenger plane and a giant torpedo plane; also a comparison of engines. A new method of de- creasing speed by means of wing flaps for landing in small space is shown at the lower left BS. will be equipped with air meters that will clock the air miles and in other re- spects will be strikingly similar to the land taxis. By this system, the organizers say, @ man can cover the northeastern section of the country in a day or two, a task that now would take months. N FRANCE, likewise, commuters are taking to the air. Four Paris business men recently joined in hiring planes to transport them daily from their homes in the Auteuil district at the southwest of the city, to the factory district near St. Denis on the northeast side. Where formerly It tok them two hours to cross the city, they now make the trip in about 10 minutes, In the last three years more than 300,000 flights have been made in the hited States. The mileage flown is estimated at the incredible total of 18,000,000 miles; the number of pas- are all these daredevils willing to risk their lives in the birdman’s frail craft? Take the first question. A friend of mine answered it in Los Angeles last year. “I can’t go to Catalina!” he wailed. “And I’ve longed to for years.” Pressed for explanation, he added: “I haven’t the time; and a sea trip annihil- ates my insides!” Entered a third party at this moment. ‘‘Come with me,” he said mysteriously. He called a chauffeur. By motor we reached the airdrome dock. Protesting, but pleased, my friend climbed into the waiting seaplane. For $12 he was swung across to the beautiful island in half the boat time. He suffered no seasickness. And when I asked him if he were fright- ened, he said: “How could I be? We were never more than 20 feet above the water!” a conn i | same swift plane. 47 Briefly, the air taxi will serve those pressed for time and comfort. Time is the chief element. The commercial salesman uses the airplane to cut his over- head. The capitalist uses it to save the dollars his minutes are worth. The sports- man uses it to span the miles between office and field. The film company uses it to catapult precious photos from prize fight to press, then to shoot back the newspapers by the ~~) 4 mane i. The speedy “air yacht’”’ developed by Grover C. Loening for operation on a Newport- New York passenger airline proved so successful that a number of planes of the same model have been adopted by the U. S. Army. It carries a pilot and four passengers Now the other question about risking one’s life. You’ve heard the saying, “Figures don’t lie.” They don’t, at least with regard to the rapidly improving safety of air travel. The French have the’ most extensive records on commercial travel. In 19283 their companies sent planes out on 9270 trips, covering 2,104,- 700 miles. The total number of passen- gers carried was 11,638. And the grand total of accidents for this entire period was six! OY of America’s leading commercial fliers declares that in seven years of flying, during which he has taken up thousands of trusting passengers, he never has had a single accident. “Ten times as safe as an automobile!”’ he de- clares. Like others, he points out that most of the tragedies we hear of are those due to stunt flying, or are the result of special tests by experts in the interests of the progress of the science. Devices for making commercial flying foolproof are being developed rapidly. The plane parachute is one of the latest. Folded snugly against the wings is a large umbrella-like silk bag with leading lines to the fuselage. Inclosed springs throw this parachute clear. To lighten the total weight, the engine and radiator can be released by the pilot. Thus, in emer- gency, such as engine-stall or broken wing, the plane with its passengers can float lightly down to earth with the same safety the ordinary parachute jumper enjoys. LAELICOPTER attachments also help. A helicopter, you know, is just an airship with propellers in a horizontal plane that lift instead of pull. Asa safety device the helicopter propellers permit the plane to hover when landing. Taking-off also will be much safer. Most airplane accidents occur in the first thousand feet before the pilot has height enough to enable him to volplane to a safe landing in case his engine goes dead. A plane with horizontal propellers to lift it need do no flying whatever until a safe altitude is attained. ‘The performance will be similar to that of any elevator. The pulling propellers will be started only after the machine is well aloft. (Continued on page 166)

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_POPULAR SCIENCE MONTHLY Scientists Find Marks of Ancient Desert on Arizona Rocks HE past history of the earth has included, geologists are now dis- covering, extended periods of desert climate, as well as the Ice Ages that long have been recognized. One of the re- gions that shows most clearly the evidences of desert conditions is the part of north- ern Arizona where is located the famous Canyon de Chelly (pronounced “Shay’’), shown in this unusual photograph. The rocks of this region are great masses of red and yellow sandstone, through which a long-vanished river has cut the deep gash that now is the canyon. The thin layers of the sandstone, some of which can be seen in the rock surround- ing the arched opening in the foreground, frequently contain ripple-marks made by the wind on the surface of desert sand- dunes millions of years ago, when these rocks were being formed. In other places appear tiny depressions made by the raindrops of desert showers that fell in that long distant past. These ripples and rain marks were buried by new layers of wind-blown sand before they could be erased. In the course of many millenniums they hart ened into rock. In these canyons, too, there lived some centuries ago tribes of cliff-dwelling Indians. Ancient dwellings still can be seen in niches on the high walls. Scientist believe the climate has become drier since then, for the rainfall now is insufficient to support more than a very few fa scattered here and there where springs or seepages provide water for a sort of agriculture.

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March, 1925 ITHIN a few months we may W\ see in motion pictures views of magnificent ruins and treasures that have been buried since the dawn of history at the bottom of the Mediter- ranean Sea. These wonders of a vanished civilization may be brought before our eyes as a result of the invention of a re- markable motor-driven submarine camera, which takes both still and motion pictures at depths as low as ‘2000 feet. This camera is to be used for the first time on an expedition setting forth from the United States this spring. American, French, and English scientists, under the leadership of Count Byron Kuhn de ‘Prorok, a French archeologist, best known as the excavator of ancient Carthage, are going to the coast of North - Africa, where they intend to photograph asunken Roman city, recently discovered at the bottom of the sea. They also expect to salvage treasures of tremendous value. The clearness of the water in the Mediterranean, where in many places it is possible to distinguish objects 100 feet below the surface, makes it ideal for tak- ing submarine pictures. Doctor Hans Hartman, inventor of the automatic camera, an electrical engineer of New York City, and an expert in sub-. marine research, will supervise the filming of the ruins. He is known as the inventor of an automatic deep-sea camera, de- scribed in PoPULAR SCIENCE MONTHLY, in’ October, 1917. With this, in great depths, he took numbers of pictures for the U. S. Government. THs camera, however, was controlled from above the water and pictures had to be taken without knowing what was being photographed. Doctor Hart- man’s new camera enables the operator to go down into the water with a camera and photograph whatever he chooses. The apparatus consists, essentially, of three parts, one above the other, sus- pended from a ship by a steel cable. The operator rides in the middle of the ap- paratus on a saddle within a steel cylinder 32 inches in diameter. Small portholes, closed with heavy lenses, enable him to observe the water surroundings. He enters the cylinder through a large port- hole on top. By means of telephone communication with assistants above the water, he may direct salvaging operations, carried out with auxiliary apparatus, as well as take pictures. The operator at no time is affected by POPULAR SCIENCE MONTHLY the tremendous pressure of the water at great depths. An oxygen device renews the air within the cylinder, while the carbon dioxide he exhales is absorbed by another apparatus. In great depths, where the cold is intense, electric heaters The Camera Man of the Sea With this newly invented undersea camera, an expedition of scientists this spring hopes to make motion pictures-of a sunken Roman city in the Mediterranean. The operator is lowered from a ship in an armored cylinder, from which he operates the camera and a powerful light projector. Note the small motor-driven propellers by which the position and direction of the cylinder are controlled 49 Diver to “Shoot” Deep-Sea Movies ; New Submarine Camera Will Photograph Sunken City keep the interior of the cylinder warm. Switches and pushbuttons enable the operator to control every part of the ap- paratus electrically. A small watertight compartment out- side the operating cylinder contains the camera. It slides up and down a double rail and is controlled by means of a small electric motor. The operator takes pic- tures by pressing buttons on a switch- board in the interior of the cylinder. A THE rear of the large cylinder, near the bottom, is a small propeller driven by an electric motor. This keeps the apparatus moving forward with the ship instead of dragging against the re- sistance of the water. When the mother vessel is not moving, operation of this propeller makes the cylinder assume an angular position, valuable for taking certain views of submerged objects. Two smaller motors and propellers are provided on each side of the cylinder near its center. These also will move the ap- paratus forward or rotate it around its vertical axis. Thus the operator can turn with the camera in any direction, or in- cline the camera, with the entire structure, at an upward or downward angle. Above the cylinder in which the operator rides is a powerful light pro- jector. This has a motor-driven move- ment by which it can be swung vertically within an angle of 90 degrees, thus per- mitting a beam of light to be directed at an angle within 45 degrees, either up or down. Water-cooled mercury-quartz burners are arranged to reflect a flood of light with high chemical reaction upon the object to be photographed. Current for the light comes from above the water by means of a cable. O MAKE the objects stand out clearly in submarine photography, Doctor Hartman has devised an artificial screen or background. This is made by filtering a chemical fiuid into the water from above. It reflects the artificial «light, which otherwise would be lost in the dark distances of the sea. The third part of the apparatus is a short cylinder suspended electromag- netically below the main steel cylinder. This contains storage batteries for driving the motors and overcomes the buoyancy of the structure, making it sink to desired locations. The films made on the ocean floor will be developed on the mother ship. LOO LOO LOE ELI Va we

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Eight Effective Tricks Use if You Are Attacked POPULAR. SCIENCE MONTHLY March, 1925 A New System i ge amazing tricks pictured on these Pages were developed by Mr. Frantzen after } study of the jiu jitsu of Japan and other Oriental] systems of the science of self-defense. They are now = taught by him to the recruit policemen of New York City to If a highwayman suddenly covers you with a revolver while his companion seizes you from behind, it is best, prob- ably, to obey and “Put up your hands!’ If any one seizes you by the throat, or by the lapels of the coat, your defense is simple, as shown in the next picture Here is an effective defense against attack by knife, club, or fist. First, seize your assailant’s wrist in a tight grip with your left hand, as shown Don’t keep them up, however! Bring the left arm down smartly, striking the wrist of the man hold- ing the gun with the side of your open hand. This will knock the gun from his hand. At the same time seize the arm of the oy man behind you with your right hand Clasp your hands and bring them down smartly about your assailant’s neck. This will cause him to bend forward, as shown above. At the same time raise either knee —and the fight will be over Bring your right arm about the inside of his, seizing your own left wrist, as shown in the picture, and pushing backward steadily with all your might Then bend over swiftly, turning your body to the left and stepping forward with your right foot. At the same time bring up your left hand and seize the left arm of the man at the tear. The leverage of your body will hurl the latter over your shoulder and his falling body serves as a club to bring down his companion ‘This system of self-defense is suited admirably to women who are forced to go unescorted into lonely or dangerous places. In the trick shown above, the — heel of the hand is thrust against the 7 attacker’s chin, while the fingers are~ pressed between his upper lip and nose, 7 Pain forces him to release his grip No matter how strong your assailant may be, he is forced to drop his weapon, to bend backward and fall helpless to the ground. If he resists, his arm will be broken by the leverage of your grip

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| 4 ome is yee March, 1925 of Self-Defense In the above and the succeeding two pictures Frantzen demonstrates how you can perform one of his best tricks. Hurled to the ground, and with a strong, heavy man kneeling on your chest and choking you, it would seem that you would be helpless. Yet by a few slight movements and the appli- cation of force at the proper time and place, not only can you free yourself, but in addition you can render your assailant incapable of movement Another trick peculiarly suited to women. Slip quickly behind your assailant, seizing him around the neck with your left arm while with your right grasp his left arm, as shown Here Frantzen demonstrates another Simple way to protect yourself against attack which will prove effective against an armed enemy as well as an umarmed one. The as- is shown at the right of the picture with his arm poised to strike elbow. POPULAR SCIENCE MONTHLY BY THE utilization of scientific prin- ciples of leverage, this system en- ables the small, light man or woman to resist successfully the most savage at- tacks made by heavier, stronger persons. Mr. Frantzen is slight, yet he has van- quished giants Seize the other’s right wrist with your left hand and his right arm above the If you are suddenly attacked on the street, an easy way to defend yourself is to kick your assailant’s leg behind the knee; with your heel and push against his chest with your open hand As the other rushes at you, scize his wrist and upper arm, pushing gipward on the former and downward, on the latter with all your strength. Contin- ued pressure finally forces hijn down Apply a twisting motion to the wrist and also push outward on the arm Posed Especially for PoputAR SCIENCE MOoNnTHLY by William Frantzen Inventor of the System, which He Has Taught Police of America and Europe Once again leverage, applied at the proper place, will force your assailant to give way. The pain caused by the twisting of his arm makes him re- lease his grip on your throat and in- voluntarily fall back in the direction in which you are exerting pressure. Continuing to twist, you force him always backward until at last he falls across your body and at right angles to it. Then it is a simple matter to seize him between your legs, and hold him in a firm grip until help arrives Simple though this trick may seem, it is most effective if performed correctly. The kick behind the leg causes the other’s knees to give way, while the push on his chest, delivered at the same time, throws him off balance. Try it, but be sure to supply your spar- ring partner with a soft place to fall This is in effect a variation of the familiar “hammerlock”’ of the wrestler. The strongest person is quite helpless under this hold if it is applied with sufficient strength and quickness. The police find this trick particularly effective in overcoming an unruly pris- oner, for it renders him helpless

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52 POPULAR SCIENCE MONTHLY March, 1928 Motorized Sleigh Skims Yukon Ice Ingenious Spiral Propeller Devised to Replace Dog Teams = By €. G. Percival HE 450-mile journey down the Yukon River from White Horse to Dawson, Y.T., accomplished in summer by stern-paddle steam- beats, becomes extremely difficult and expensive over the ice and snow of winter. Then relays of horse-drawn sleds and dog teams. replace the swift-moving steam- ers, and it takes from five to seven days to complete the trip—a cold and tiresome journey. Horse teams are changed every 22 miles, which necessitates the maintenance of 35 stables and rest stations, with costly live stock and large personnel. The item of. feed for the horses alone is a stagger- ing expense, for hay de- livered at any point on the route costs $100 a ton. Impressed by the vast difference between gasoline at 22 cents a gallon and hay and grain at $100 a ton, em- ployees in the shops of the White Horse & Yukon Railway built an ingenious motor-driven sleigh as a substitute for the conventional horse-drawn vehicle. The only motor available was a 48- horsepower, four-cycle, four-cylinder en- gine with magneto ignition, four-speed sliding gear transmission and leather- faced, cone clutch, from an American automobile of the vintage of 1910. This The ingenious motor-propelied sleigh on Lake Le Barge, Y.T., between White Horse and Dawson City. Note the spiral screw was overhauled, mounted in a sleigh and connected with a screw propeller in the shape of an Archimedean spiral, placed beneath the sleigh and to one side, by chain and sprockets of exceedingly low gear. Turned by the motor, this propeller bites into the ice or the snow crust, and pulls the sleigh forward. A single gtee}. shod runner in front steers the odd craft while long steel runners in the rear, at each side of the propeller, supply balance. Obviously in soft snow the motor. sleigh would be practically use. less, for the propeller would merely discharge the snow at the rear without causing the sleigh tg move. But on ice, or on snow that possesses a strong crust, the sleigh and its laden trailer move at about 10 miles an hour. American engineers, comment. ing on the motorized sleigh, ex. pressed the opinion that the. de. vice was ingenious mechanieally and possessed inventive possibili- ties, but -raised the question whether such a screw device would prove more effective than a eat erpillar tractor that would oper though possibly not at equal speed. “No doubt,” said Carlos de Zafra, of the Department of Mechanical Engineer- ing, New York University, “ continued ex- periment will disclose the best pitch of screw for average conditions, minimum of weight for a desired tractive force, as well as maximum hauling capacity beyond which slippage of the screw on the ice would be excessive, also a method of flexible mounting to facilitate steering. “The device seems deserving of develop- ment along lines that the peculiar local conditions would dictate.” BEAN BEETLE DISTRIBUTION beans before them, hordes of bean beetles from Mexico have been advancing steadily north- eastward through the United States during the last four summers: The pests were first reported in the East in 1920. Since then they have reached the shores of Lake Erie and the Atlantic seaboard states. The bean beetle closely resembles the inoffensive ladybird beetle of the same family. It is copper colored, about one-fourth of an inch long, with eight black spots on each wing cover. It feeds on the under surfaces of the bean leaves. ) [rest before great fields of IN EASTERN U.S. 1924 @ JSOLATED INFESTATION omens ESTIMATED Arsenate poisons, sprayed under the leaves, offer the most effective means of combatting * The Inyasion This map shows how the ravaging bean: beetles have spread northward and eastward from Alabama since 1920. By 1921 the invaded area had increased sixfold, extending iato Georgia and Tennessee. In 1922 the invasion was carried into Kentucky and the Carolinas, and in the next year pushed northward into Ohio. The pests in 1924 reached Lake Erie. This is the third imsect immigration from Mexico, the other invaders being the boll weevil and potato beetle the pest. te an Beetles Spread Destruction How the Pest Develops Within a few hours after the eggs (A) of the Mexican bean beetle have been hatched, the larvae (B, C, D, E) begin feeding on the under side of the bean leaf. The larva reaches a pupa or inactive stage (F) when it is attached to the leaf by a skin. When the adult (G) emerges from the pupa it shows no markings, but spots soon appear on the copper-colored wings. The adult attaches itself to the under side of the leaf where it eats ragged patches. Bean plants attacked by .. the beetle are left a fibrous-net- work that shrivels in the sun. After destroying the foliage, the insect may attack the pods, and even the stems ate over soft snow as well as ice, -

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% , eX- ine Gedbielfeveleres:f POPULAR SCIENCE MONTHLY For six weeks this great torrent of lava flowed silently down the side of Mt. Mauna Loain Hawaii. Doctor Jaggar discovered during his observations that volcanic lava flows in tides, and that upon its movements depend the frequency of earthquakes A New Way toFameand Adventure Noted volcanologist tells of thrills and opportunities to be found amid fiery craters at the edges of the world ES legos JAGGAR is recognized as a leading authority on volcanoes. He is Scientific Director of the Hawaiian Volcano Research Association, in charge of the observatory at Kilauea volcano, maintained by the United States Weather Bureau.— THE EDITOR. XPERIENCE has taught me that kK when I meet new people I must be prepared to answer one or both of the following questions: “Why do you study volcanoes?” “Don’t you find your work very dangerous?”’ The answer to the first question cannot be given in a word or two. Volcanoes are studied because they are the most likely source of fundamental knowledge regard- ing the structure of the earth. They are manifestations of the things that are within the earth, and conse- quently offer a way of peering beneath the earth’s crust and By T. A. Jaggar, Ph.D. re In the Glow of the Crater Camped in cone tents on the high flank of Mauna Loa durinz the 1914 eruption, Doctor Jaggar and his fellow explorers could hear the rumbling and see the distant glow above the crater. The photograph shows their camp at night, illuminated by the glow of molten lava teristics so that volcanic eruptions may be predicted and the world spared the frightful loss of life that has accompanied many volcanic disasters. HE second question that people ask me I can answer by a single word— “No.” Despite the popular delusion to the contrary, volcano and earthquake lands are not dangerous. I have knocked about volcanoes for 30 years, walking to the innermost edges of craters, and climbing over hot lava flowing in a tunnel beneath me. I have felt earthquakes innumerable, of the volcanic and after- shock kinds. I have rushed post haste to disaster localities like a reporter to a fire. And yet, after living continuously for many years at the Hawaiian volcanoes, and after travels to 10 other regions where my job took me, I have to confess that never once have I felt particularly un- easy, nor found myself solving its mysteries. Studying the interior of . the earth through vol- canic action requires the finest instruments of modern physics, and might be compared with the study of the insides of man by means of the X-rays. There is another rea- son, too, why volcanoes are studied, and that is to learn as much as pos- sible about their charac- | SPE PN vee GR ne SA RE The fire pit of Mt. K ilauea, brimming full of lava, as it appeared in ‘March, 1921. The spectacular photograph was taken by Doctor Jaggaf from a height a mile away thrilled with the heroism pictured in the movies. Of course, there are risks, but the most serious that I can recall were due to storm and exposure. On a volcano called Korovinski, in Atka, in the Aleutian Islands, I was stormbound for two days in 1907 with one companion, in a little silk cone tent. The wind blew so hard we had to ple sieeade = aks TS ee

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(POPULAR SCIENCE MONTHLY this we made bivouac all night at the foot of a line of fountains of fiery froth 200 feet high. These fountains would build up cones, and change location. The lava surged and sprayed like Roman candles. About 3 A.-M. came the climax, when fountains of bright orange incandescence lighted up the whole landscape and shot 400 feet into the air. Out of the glowing mass, which really was coming from a crack in the flank of the mountain, sped a network of lava streams that united in a steady river. This meandered away into the distance like a fiery Mississippi in a red hot flood plain. Over the brow of the mountain it went, and down through the forest 12 miles to the sea, where it poured unde: the ocean for six weeks. We had to dodge the gas, and move back when the wind veered, and we were very weary and often wet and hungry. Now and then we ran into wild cattle, and occasionally I took a chance by March, 1995 flow came down by the shelter and thin got too hot. Even in our new positi the green wood posts of our shelter ae times caught fire from the -hot ground My wife, who kept us supplied with food and cheer, one day dropped her gloy in the shelter. They fell across ga tie and were soon afire. WE FOUND there was a laya tide sure enough and the 20,000 obser. vations of that month have yielded: y secrets of Mother Earth that no one knew before. This discovery of regular move. ments in the Hawaiian lavas under ¢ earth crust is being extended to quartey and half-yearly phenomena shown by the charts of rise and fall. Upon the mye. ments of the lava depend the frequencies of the earthquakes. All of this informa. tion has been compounded into a about nine years long for Mauna Loa and Kilauea, robbing them of much. of their ancient mystery.

Spouting Fire A marvelous nighttime pho- tograph of a spouting lava vent on Mt. Kilauea. Doc- tor Jaggar set his camera up 25 feet from the fire-splash- ing cone and left the lens open for several minutes take turns holding up the jointed tent pole all night. We struggled through the rain to a place of steam and boiling springs, and we saw volcanic cinder fresh on the snow. After two nights of this .we shouldered our packs and set out for our schooner. The grass over which we walked was as slippery as the ice. At last we came to a slope, flat at the bottom, but leading to a second slope that proved to be a precipice. Our idea was to slide down the first slope and stop at the bottom, but we had not realized how slippery the grass actually was. tidal force. I WENT first, slid all the way across the flat stretch, and shot into the air, shouting to my companion to dig his heels in and stop if he could. But there was no stopping. The drop was about 30 feet, and I landed in the middle of a deep pool 6t water along a stream course. A fraction of a second later my friend came hurtling through the air plump on top of me: Nobody was hurt, and we were already as wet as mortals could be. Then we found the river was in flood, and had trouble getting across it and finding our food cache. After that there were miles and miles of soft marshy ground that went “‘squelch-squelch”’ un- derfoot. When we emerged at last at Nazan Bay and reached our schooner we were about the happiest and tiredest men alive. That is a fair sample of the sort of adventures I’ve encountered while study- ing voleanoes. Whatever danger there was came not from the volcanoes them- selves, but from cold, rain, and snow. Of course, there is excitement and in- terest during a spectacular eruption such as that of Kilauea in 1919. To observe 2 Kilauea’s Lava Lake Rises and Falls Fiery fountains splash at the edge of the liquid lava lake of Kilauea, which rises and falls rhythmically as though actuated by a

A view from the high rim of the crater’s edge clambering’ up a hot lava cone to photo- graph what was inside. But the sense of actually being in danger was not present, and nobody was hurt. By far the most interesting experiences I ever have had with volcanoes began in 1919, when I began my investigations at Kilauea to ascertain whether the lava had a daily tide. Several young men volunteered to help me, and I set up a transit at the edge of the fiery lakes and made a camp there. The object was to read angles vertical and horizontal for a month every 20 minutes. We organized day and night shifts. ‘Ts man who had to keep his eye at the transit between midnight and 6 A. M. had a somewhat spooky time, with hot, hard lava in motion beneath his feet, and the hot lake lava rising and sometimes overflowing in front of him. He had to watch the lanterns at the bench marks. All the transit readings at night had to be made with an electric torch. Sometimes there were earthquakes. The ground was tipping, so that the index error was rapidlv,<thanging and adjust- ments of levei pubbles were called for irequently. Twice we had to move the transit position First because a wall of lava built up/in front, and second because a In other words, when we know all about it, we may hope to predict pretty well what the volcanoes are going to do. And once the volcanoes are ¢gp. quered, it is only a ques tion of experience and ex. periment to apply similar reasoning to earthquakes, As a matter of fact, even with the incomph knowledge of voleanp existing today, many Ya canic eruptions can be predicted long enough be fore they occur to preye loss of life, for volean often give unmistakal

A Fountain of Slag This gigantic slag fountain, 200 feet high,» was found at the source of the Mauna Loa . lava flow in October, 1919. To take this re markable photograph, Doctor Jaggar rushed” up the cone with his camera and stood within — 50 feet of the ranidly falling fragments forewarnings of their intentions a few days, and sometimes a few weeks, befor an eruption. Even the great Mt. Pelee disaster at Martinique, one of the most (Continued on page 168) a

But

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March, 1925 POPULAR SCIENCE MONTHLY From Jungle Smelting Pit to Modern Blast Furnace UR FOR BUILDING THE PLAN OF BB PRI MITIVE FURNACE FURNACE (2) THE FURNACE STARTING To OPERATE Pieces of ‘ as Ant hilt lumps of Ant-Ail] being S butt up J fe forn, : on lumps of Ant bill © Prpes brou Charcoal “Burn? grass. reeds, ete OE ae fe correct level 3 huachofgrass ee aaa GROUND fe i a oe pipe Bon ? GROUND AFRICAN AIR-TUBE Pipes from t : eg Hows (S) ticks for ¢ erating Lelio SECTIONAL VIEW OF THE BLAST FURNACE USED BY THE NATIVES OF -_ IN OPERATION A sin ERN WATER-COOLED AIR Sie htt ee eles BM insien. omen otis i ta a eee ~ Level of ground, ODERN BLAST FURNACE ~ ITS EQUIPMENT. BUNKERT menu tt 8 wii "gs Chute eon immense size and marvelots machinery, today as their ancestors did for centu- their fundamental operation has been ries; and in its essentials their method REAT blast furnaces for saatiine iron that loom up in our industrial cities, might be thought a de- velopment entirely of modern civilization. ut, as a matter of fact, with all their changed little since the dark ages.| Tribes in the depths of Africa, where white men seldom have penetrated, are smelting iron shows surprising similarity to the modern system. Both methods are pictured. (Continued on page 56)

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cha tah tan se ‘ space the new skyscraper had POPULAR SCIENCE MONTHLY March, 1925 Skyscraper Built through Eight-Foot Door eight feet square, a 16-story steel-and-concrete skyscraper was constructed recently within the John Wanamaker department store in New York City, in making an addition to the building. To accomplish this surprising engineering feat the workmen had to carry every piece of machinery, every beam of lumber, and every steel girder through the single narrow opening. And they did it without disturbing business in the old building in the slightest degree! Before remodeling, the building had a rotunda in the center, 60 feet square, which extended through the 16 floors from basement to dome. In this Teen te one small door only a to be erected. The eight-foot door through which the thousands of tons of building material and hoist- ing machinery had to be car- ried was on the street level. Before be- ginning work on the new building, 18,000 wheelbarrow loads of wreckage and waste material from the rotunda had to be carried to the street through this same door. Included in the material that was pushed through the eight-foot opening were eight elevator motors, each weigh- ing eight tons, eight elevator generators of one ton each, 108,000 square feet of flooring planks, 9166 loads of hollow tile, 3000 bags of plaster, 6000 loads of floor arches, 1000 wheelbarrow loads of bricks, 1800 loads of ceiling material, 3000 scaffold planks, and 7000 feet of guide rails for eight elevators. Shut off from the store by board par- Workmen hauling one of the heavy steel girders for the 16-story skyscraper through the single eight-foot opening titions, the progress of the work was so unno- ticed that when the new store-within-a-store was opened to the _ public, it was viewed with great surprise. Occasionally, during the construction, a customer dis- covered a door through this partition, but there always was the sign, “Danger! Keep out!” to check his entrance, The addition, which is 230 feet high, gives the store 51,200 additional square feet of floor space. While it bridges each floor, the structure is an independent unit, so that it would stand alone if necessary. The entire unit was com. pleted in four months of work. A Sea-Going Foundry OH of the latest additions designeg ‘ for the U. S. Navy is a floating foundry to be used for making major ' repairs and replacement castings for the ships of a battle fleet. This vessel, it is reported, will be one of a new group that will constitute the “ works” of a fleet at rest or in mo tion. It is more than 400feet long, of 70-foot beam, with 10,000 tons displacement, and in- cludes a complete pat- tern shop and foun- dry and a multitude of other shops, all manned by a large force of me- chanics. The to- tal floor space is nearly 5000 available square feet. Two cupola furnaces and four oil-burning crucible furnaces, all located on a third deck; consti- tute the melting equipment. The larger of the cupolas, with its stack, is some 60 feet high—high enough above the upper deck to allow the gases to blow clear. a) Smelting—Old and New (Continued from page 55) The furnaces of the primitives and the enormous shafts of the most improved furnaces of today have the same shape. In each, an air blast is driven in to in- erease the heat, although the hand bellows of the jungle have been replaced by bellows operated by steam, gas, or electric power. Smelted iron drops to the bottom of both in exactly the same way. th Baars African natives dig a circular pit about a foot deep and line it with clay. A three-inch layer of charcoal then usually is laid at the bottom and a fire started. This is fed with weeds and brush until there is a mass of red-hot ash in the pit. The men then build a wall around the pit, using lumps of ant-hill, and stick the blast pipes through the wall. While some are building upward, others are putting a thick layer of charcoal on top of the ash at the bottom of the pit. Above this, close to the blast pipes, they place the iron ore, and over this more charcoal. The pit is kept full of burning charcoal while the building is going on. The furnace is completed in from three to five minutes and the smelting begins. Squatting around the furnace, natives make their bellows go at full blast, and keep it up for four or five hours. When the natives think the ore is smelted, they knock down the furnace walls and remove the hot iron from the pit with a long stick. The newest blast furnace consists of an upright cone set on top of an inverted one, just like those in the jungle. In size, of course, the modern furnace dwarfs the primitive one, its shaft usually towering 80 feet into the air. The blast furnace of today is kept full of lumps of fuel, iron ore, and lime- stone, which are fed into the enormous shaft from the top. Trucks carry this mixed material up a track to the top of the furnace and drop it into a hopper. HE mixture descends slowly as the bot- tom of the column is eaten away by the coke burning in the hearth. This coke is kept blazing by hot-air blast blown through tuyeres or holes near the bottom of the hearth, just. as in the African furnaces. The ~‘ifrican tuyeres made of clay have beer replaced by ones of iron or bronze, cool’ 1 by a coil of water pipes. As hot gases rush upward from the burning fuel, they remove oxygen from the iron at the top of the furnace, and the other minerals in the ore combine with the lime of the limestone and the ash of the fuel to form slag. By the time the iron has sunk to the top of the ower section of the furnace, both the iron and the slag have melted and trickle down through lumps of burning coke. They collect in the hearth in two distinct layers, the iron below, and at intervals are drawn off through holes. QCIENCE taught men that if the eir forced in by bellows to burn the fuel was preheated, an astonishing saving of. fuel could be effected. So in modern iron smelting, three or four huge stoves are built around the blast furnace to heat the air blast. One of the most effective types is the Cowper stove. This contains in its interior several firebrick walls with spaces be tween. The waste gas from the top of the smelting furnace is conducted through @ pipe to the stove, where it is burned, heating the bricks to a high températute. Then the gas is turned off and the ait blast run through and heated by the hot brick surfaces before going to the — furnace. Several stoves are used so tha while the gas is turned on in one, air may be passing through another, thus keeping the blast hot at all times. a

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March, 1925 POPULAR SCIENCE MONTHLY How Locomotives Are Kept Fit Millions Spent Each Year to Overhaul Giants of the Rails big THE effort to provide safe and de- | pendable transportation, our railroads spend more than half a billion dollars each ; ar year to keep steam locomotives in repair. In the Smoke-Box Several hundred thousand men are employed , : to maintain the nation’s locomotive and car Once in every six months a equipment. These pictures show various locomotive requires a general stages in the overhauling. One of the overhauling of hardest jobs is the renewal locomotives of flues, because of the nar- row working space. The pic- ture below shows railway men at work in the smoke-box 57

New Tires Driving wheels are removed and flat tires turned to new contour on a large wheel lathe

In a Sling To remove the driv- ing wheels, the en- tire locomotive is hoisted by a giant crane. Notice how the locomotive is carried in a cable sling from the hook of a great crane <« ts A general overhauling of the boiler and running gear is required ; Wy om to put this locomotive in good running condition. The smoke- 1 eo A. 7 mee box front has been removed and a workman may be seen inside Si a ‘ cs | ae

PF ». 2 D ie atl e

<<« Renewing the Boiler Supported on jacks, the locomotive at the left is undergoing a general overhauling of. the boiler and firebox, while waiting for a new set of tires. The two workmen seen at the rear are putting new ‘staybolts in the firebox

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or cceteneaur mene § i 4 ~ 4 = oe | am Sailing in a Soap-Box Most every boy has built a soap-box wagon, but how many have thought of attaching a sail? This lad of Sydney, Australia, did it with a sugar bag and a couple of sticks A.Forester’s Cyclometer E. C. Solinsky, chief forester of Yosemite National Park, devised this horse-driven cy- clometer to measure the 600 miles of trails in the park. It con- sists simply of a bicycle wheel, with cyclometer, on along pole POPULAR SCIENCE MONTHLY Home in a Boat—When the cold winter months came, Charles McKown, of Winthrop, Mass., pulled his houseboat up on the shore of Boston Harbor. He added a storm door and weather strips for the windows, converting the three- room boat into a very comfortable home during the severe weather, high and dry above the incoming waves in *. Z ? a * Cael et a él March, 1925 ddities from the Queer Inventions and Original Ideas Canoe on a Motorcycle For the ideal day’s outing at lake or Stream ra an English manufacturer has just devised ‘ this comfortable canoe sidecar for the motor- 2 cycle. A young woman can enter the canoe - from her front doorstep, with cushions and a parasol. Arriving at the water, her escort simply detaches the canoe and launches it Rescued !—Equipped with improved gas masks and safety lights, a rescue crew of the U. S. Bureau of Mines is seen emerging from a burning mine with an overcome miner Touring in a Log—E. C. Case, of Bellingham, Wash., recently completed this unique three-room home on wheels that once was part of a giant Douglas fir-tree. It boasts conveniences not always found in stationary houses

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it RaOas March, 1925 POPULAR SCIENCE MONTHLY ed World’s Scrapbook Found Here and There by Camera Men ~ eae > ts “Ney =a Windshield for Motor Pacing Training daily behind an odd new type of shield attached to aracing car, M. Miguel, one of the foremost cyclists of France, hopes to break the motor-paced cycling record Testing, His Heart In a London veterinary hospital a spiral spring stethoscope recently was introduced to sound out the hearts of dogs that go in for treatment While excavating in ‘ Seattle recently, Wood Pipe Line workmen uncovered 62 Years Old _..._ apipe line of bored fir logs, a relic of pioneer days. It was part of the city’s first water system, laid in 1863. Connection between logs was made by a wooden sleeve. Iron bands kept the logs from splitting Bike of Sticks An Englishman living at a distance from his work wanted a bicycle, and saw possibilities in a hedge fence .near his home. In a short time he had completed this odd bicycle. It is built entirely of hedge sticks. Every day for years the inventor has been using his queer looking wheel, which still gives good service. The parts of the frame are arranged like those of an ordinary bicycle. Notice that a crotched stick serves as the fork for the wheels Dwarfing a Man—These enormous cast-steel pipe fittings recently were turned out by a Chicago manu- facturer. The fittings were made especially for use under 450-pound steam pressure in the main steam line of a Detroit, Mich., electric-light company il Testing Hosiery—To determine the relative merits of different brands, the Bureau of Standards has devised a method of stretching stockings over boards, where they are dried electri- cally. The hosiery previously is washed, dyed, dried, then washed again, to determine whether it will hold its shape and how long it will wear, and thus a standard is establisned

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Panama 60 POPULAR SCIENCE MONTHLY The Month’s Useful Contributions to the is discovering new secrets that will make human life healthier, richer, and happier. The explorer is pushing into the unknown and bringing back new facts about the world we live in. The inventor is creating new tools, machines, and methods to lighten labor and increase our comfort. Science moves swiftly forward. Its record of achievement grows too vast fora busy world to grasp. It is to help you keep step with new dis- covery that PopULAR SCIENCE MONTHLY publishes here a résumé of the month’s important contributors to _ scientific progress. The Deaf Hear by Touch T° TEACH the totally deaf, hitherto incurable, to hear through the palms of their hands is the amazing purpose of an instrument invented by Dr. Robert H. Gault, professor of psychology at Northwestern University. The device has not yet been developed to the stage where it may be applied universally for the relief of deafness, but with the aid of the instrument Doctor Gault has suc- ceeded in teaching five deaf persons to identify perfectly 15 sentences containing 90 one-syllable words. The instrument somewhat resembles a telephone receiver and operates on a similar principle to the telephone, except that, instead of carrying sound vibrations to the ear, it causes them to reach the hand or some other sensitive part of the body. It is neces- sary, then, for the person using the ap- paratus to recognize what speech sounds caused the particular vibrations he detects yi di day the laboratory worker through his sense of touch. This is not easy, Doctor Gault says, yet it is scarcely more difficult than is learning what simi- lar combinations of vibrations mean when they fall upon the ears of normal persons. Some time ago Doctor Gault conceived Improved Compass for Fliers The invention of the earth inductor compass has brought greater safety to fliers in clouds, in fogs, and at night. Now the inventor, Morris M. Titterington, is at work on a new model of the compass, which will be operated electrically, and which, he believes, will be even more accurate and reliable than his previous invention. He is shown here work- ing in his laboratory at Brooklyn, N. Y. © Keystone March, 1925 New Instrument Enables the Deaf to Hear with Their Hands Progress of Science the idea that the sense of touch might possibly be substituted for the lost sense of hearing. His invention has proved 80 successful in actual use by deaf Persons that Doctor Gault has obtained leave of absence from Northwestern University to perfect the apparatus under the auspices of the National Research Council. Brings Hearing to the Deaf Dr. Robert H. Gault, professor of psychology at Northwestern University, is shown here demonstrating the marvelous new instrument he has invented to enable the deaf to hear by touch. The receiving instrument (at left), resembling a telephone receiver, carries sound vibrations to the palm of the deaf person’s hand or to some other sensitive part of the body New Light on Hypnotism ‘TRE hypnotist who causes another person to commit crimes for his benefit when under his spell is purely a fictional invention, according to a recent announcement of Doctor Delboeuf, a French physician, who is an expert on hypnotic influence. Experiments con- ducted by the French scientist show, he says, that persons when hypnotized will not perform acts that are repugnant to their conscious minds. A subject whom he had hypnotized, Doctor Delboeuf asserts, when given 4 bottle, a stick, or some other harmless object and informed that it was a pistol, would “shoot” any person designated. If given a real pistol, though, even if unloaded, the subject would not pull the trigger when directed to use the weapon against any one. A Foe of Disease Germs N AMAZING scientific achievement, one that may hold important possi- bilities, came recently when Dr. Robert ology of } ing 0] teriou 1 0 “e F t tl i

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» 1925 if ce might , Sse ved so ersons ave of sity to ISPices logy here ment ar by left), 'son’s body ‘ism another for his urely a , recent veut, a pert on ‘S COn- 10w, he ed will nant to rotized, ziven a armless . pistol, gnated. even if pull the weapon “ms 4 ement, t possi- Robert March, 1925 : Cc. Green, assistant professor of bacteri- logy and immunology at the University of Minnesota, succeeded in| isolat- in disease bacteria cultures a mys- aieak substance believed to consist of ” eee” ee a POPULAR SCIENCE MONTHLY Josef ‘Land from which the flight over the Pole will be attempted at the first favorable opportunity. The scheduled course is the same as that planned by Captain Amundsen. X-Ray Treatment for Whooping Cough Proves Successful To combat whooping cough, which ‘causes nearly 10,000 deaths a year, the medical staff ‘of the’ On Shore Department of the Boston Floating Hospital recently adopted X-ray treatment. The results were so effective that the new treatment is being tried by hospitals in- New York, Chicago, San Francisco, and exceedingly minute organisms that live as parasites on the disease germs. The substance, he claims, will kill the most deadly disease bacteria even when in a solution diluted a million times. The discovery was made by filtering bacteria cultures of dysentery, typhoid, diphtheria and other infectious diseases through stone filters. The result was a clear white liquid that contained no disease germs. When added to a germ culture, one drop of the liquid killed and completely absorbed the bacteria it contained in a few hours. Even when diluted a million times, the substance still proved deadly to the germs. Several reasons are noted by Doctor Green for believing that the substance consists of tiny living things that prey on bacteria as bacteria prey on man. Attempts New Polar Flight ROM France comes word of another projected airplane flight over the North Pole. This expedition, partly fnanced by the Government and partly by private interests, will be under the leadership of Jules De Payer, who was one of the first men to suggest the air- Plane as a vehicle suitable for arctic exploration. It may be recalled that De Payer planned a flight across the Pole in 1913, and had made a preliminary reconnaissance when the European war forced the abandonment of the project. De Payer now announces his intention of starting early in the spring for Franz Montreal. From 15 to 20 per cent of 700 cases treated are said to have shown improve- ment within 24 hours. In the remaining cases, with the exception of two deaths of babies, the improvement was rapid. The photograph shows a child undergoing the new X-ray treatment in the Boston hospital Creating Motor Fuels io ENGLAND, France, and Germany, where the supply of oil is not plentiful as ours, chemists are busy searching for fuel substitutes, especially for gasoline, against the day, often predicted by geologists, when the world’s store of petroleum will approach exhaustion. From England recently came a report How U. S. Tests Cables to Prevent Accidents To prevent frequent accidents caused by the breakage of wire rope used as elevator cable, bridge cable, or for hoisting, the U.S. Bureau of Standards is at work to perfect a reliable method of testing the rope without removing it from service. The photograph shows R. L. Sanford, chief of the Magnetic Section of the bureau, operating a new machine for producing wear on From his calculations he hopes to determine weaknesses by the wire’s magnetic changes steel wire under controlled conditions. 61 of a method worked out by scientists of the Department of Scientific and Indus- trial Research whereby, through low- temperature carbonization of coal, there is produced a gaseous fuel suitable for home or industrial use, an effective gasoline substitute for.motors and a solid smokeless fuel that can be used as a substitute for coal. In Germany, according to recent reports, there has been developed a process of manufacturing synthetic petro- leum from powdered coal treated with hydrogen under high temperature and pressure. The resulting product, even if derived from low-grade lignite, it is said, is quite equal to natural petroleum for motor fuel. An even more remarkable achievement is that credited to French engineers and chemists, who are said to have perfected a method of obtaining gasoline of higher heating efficiency than that obtained from petroleum, coal, wood, or any other carbon-bearing material. The process is said to produce gasoline at a cost of 12 cents a gallon, which is less than one- third the retail price for natural gasoline in France. No Insect ‘‘Languages’’? HE “voices” of insects always have been of peculiar interest to mankind. | Many naturalists and entomologists have sought to interpret these sounds, and some have claimed to be able to dis- tinguish between the battle cry of a cricket, say, and its love song. Now comes Dr. Frank Lutz, curator — of insects in the American Museum of Natural History, New York City, to assert his belief that the sounds of in- sects mean nothing—even to the insects themselves. Insects squeak, buzz, or hum because their body conformation is such that they cannot help making a noise when they move, he thinks. The sounds they make, he says, probably are often embarrassing to them, just as the rattling of the armor of knights of old often betrayed their presence to their enemies.

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Handy New Kitchen Stool Is also a Stepladder LACED upside down, this convenient kitchen stool is a stepladder. The steps are covered with rubber mats to prevent slipping. The stool is finished in enamel.

Folding Iron Bed Invented for Small Apartments i/ SEN extended, a new type of fold- ing bed, invented by Reuben Haight of Hudson, New York, looks like an ordinary iron bedstead. By means of the hinged iron side supports, which ex- tend from head to foot, the bed may be telescoped until it occupies only 18 inches of floor space. The mattress is in two sections and each section fits into the bed when folded. Sufficient room remains to hold the bedclothing. The construction of the hinges prevents the bed from refolding when once extended.

cause of many motor accidents. POPULAR SCIENCE MONTHLY . How Many of These March, 1925 Slot Machine Serves Sandwich Lunch URING the too-short noon hour this newly invented automatic restaurant should prove popular. It is a container filled with sandwiches and pieces of pie. Drop a dime in a slot, pull a lever and you have your lunch, without standing in line, or tipping a waitress. The sandwiches and pie are wrapped in paper. Clears Show Window HE fogging of show win- dows, if they are of the boxed-in type, may be pre- vented by placing a flat glass or porcelain dish containing calcium chloride in the window. This chemical substance quickly ab- sorbs moisture from the air, with the result that the moisture is prevented from congealing against the outside glass. The contents of the dishes must be renewed every two or three days, and the moist calcium chloride thoroughly dried, after which it may be used again.

< Disk Signal for Traffic ‘Ts German policeman regulates traffic at night by means of an illuminated disk. It is operated by an electric battery in his overcoat pocket. A portable signal of this sort might be used to advantage on dangerous country crossroads where traffic is heavy, and where the lack of warning signals is the

How the new iron bed appears when folded and when opened. Notice the hinged side supports that fold upward; also how storage space is provided for the two sections of the mattress in the folded bedstead Hand Lettering Made Easier by New Stencil Outfit O ENABLE draftsmen to do more perfect lettering in a fraction of the time ordinarily required to accomplish it

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Complete stencil outfit for lettering freehand, a new type of stenciling outfit recently has been devised. Its use is said to give a more professional appearance to the work of amateurs who make occa- sional posters or sign cards. The stencil is in the form of a rule from which geometrical figures have been cut. These are in shapes that are ample for forming various parts of printed letters.

New Aid to Naturalists— the ‘‘Telemagnifier”’ HE latest instrument devised for use by naturalists in field study is known as the ‘“‘telemagnifier.”” It combines the advantages of the magnifier or reading glass, and the field-glass or telescope.

Elec py EN their kitchen | A novel js in the tion elec electric § The g

Elec ESS and

The when t' spacing plished The is struc typing, and the machin This

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h, 1925 asier fit ) more of the plish it ing x outfit » is said parance ce occa le from en cut. ple for etters. ts— 9 for use known nes the eading- pe. Ideas Can Y ou Use? Electric Grill in Living-Room Lamp NTORS are doing [ee best to move the kitchen into the living-room. 4 novel method of doing this is in the form of a combina- tion electric table-lamp and tric grill. eo grill is in the base of POPULAR SCIENCE MONTHLY the lamp. Swinging the lamp pedestal to the right uncovers the grill and switches it on automatic- ally, ready for use. The lamp remains lit if desired, or the lamp lights may be turned off while the grill is being used. Anything that can be cooked on an ordinary small grill may be prepared on this one concealed in a lamp. It operates on a house-lighting current. It is especially useful in the nursery or sickroom. TO PREVENT the rusting of metals used in construction, a New York manufacturer recently perfected a trans- parent liquid preservative that forms a tough, invis- ible, protective skin on the surface to which it is applied with a brush. This preservative is said to be proof against acid, salt water, and steam. Electric Touch Improves Work of Typists Lm fatigue for the typist and more and better work done are advantages daimed for a new electrically operated Electric motor attached to typewriter typewriter. The machine is operated in the same way as a manually operated typewriter, except that electricity, in- stead of the typist, provides the power for the key stroke. The typist presses slightly on each key and electricity com- the operation. Thus valuable human energy is saved. The 10-watt motor runs continuously when the machine is in operation. Back spacing and carriage return are accom- plished by hand. _ The uniform force with which each key 8 struck produces unusual uniformity of typing, and the action is said to be quicker and the touch lighter than on the ordinary machine. This is said to be the first time that 4 standard American typewriter has adopted an electrical improvement. Screws Driven by Hammer AMMER-DRIVEN screws are the latest time-savers for work in hard metal and composition materials. A hole of the correct size is drilled in the material. Into this the tip of the new type screw is inserted. As it is hammered, the screw cuts and twists into the material. The extreme hardness of the screw and the angle of its threads make it turn as it is driven. Hand Rail for Stepladder Prevents Accidents NSURANCE companies have com- puted the startling percentage of acci- dents occurring in homes. Not a small proportion of these are due to falls from stepladders. ? A recent invention, a safety-first hand rail, which can be fixed to stepladders, recently has been designed to make them much less dangerous. The rail is mov- able and can be drawn up as the user mounts the steps. This provides a firm hold however high the user of the ladder may wish to ascend. Baby Carriage, Rocker, and High Chair Combined BABY’S carriage, rocker, and high chair combined is the latest inven- tion for the mother’s convenience where floor space is limited. To convert the invention from a rocker into a carriage, the rockers are pulled up at the rear to form a_ pushing handle. For a high chair, the same rockers, extended, form the support. The invention used as a rocker. To form a carriage the rockers are swung upward

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64 POPULAR SCIENCE MONTHLY At the Motorcycle Rodeos New Thrillers by Dare-Devil Bike Riders » **Ride "Em, Cowboy!’’ Perfect balance, combined with complete mastery of machinery, enable motor- cyclists to perform these daring feats. At a motor-club rodeo in Camberley, England, not long ago, R. B. Rudd made a motorcycle jump of 36 feet. The camera caught him just before he landed

March ‘ 1925

‘**Bareback’’ Riding In a recent spectacular motor- cycle meet at Tokyo, Japan, one of the riders stood on the seat of his speeding machine while rounding a turn in the racetrack

Human Ballast One of many thrills in motorcycle races on the Isle of Man, Eng- land, a few months ago, came when G. S. Davi- son rounded a turn’at terrific speed while his human ballast leaned far to the side to hold the little side- car on the level

mae An 84-Foot Leap A record-breaking leap of 84 feet was made recently’ by G. H. Stickler at Boise, Idaho. The machine rose nine feet Balancing a cycle and sidecar on two wheels is the feat performed by L. A.-T: Peterson of Waterbury, : Conn. He uses one hand and arm to balance

<—« Cycle Acrobat One of the world’s most skilful trick riding acrobats is Albert Milner of London, England. His specialty is to climb all around his ma- chine while it is traveling at the rate of a mile a minute

1 F e a

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ch, 1935 Ea ae ns RT erin. : pr A New Skimming Boat The remarkable speed of 55 miles an hour is claimed for this craft of the hydroplane type, designed in Glasgow, Scotland, to operate on the river Clyde. An airplane type engine drives the pro- peller. The hull is made in five sections int aa A bicycle on pon- =>. \ toons, geared to a a ¥ small propeller, ee 5 , travels six miles an PA DAA i ea | Against the Wind A boat built to sail against z the wind and recently tested “ in Paris, has a 30-foot sail- like propeller, which drives a screw at the stern Foot Paddles This odd watercycle, designed by a French inventor, has pedals that operate fore and aft paddle boards. One paddle _ €iters the water as the other leaves it. A speed of 10 miles an hour can be attained by this means of propulsion POPULAR SCIENCE MONTHLY Odd Ways to Go Boating ii 4 Unusual New Inventions for Water Travel Bicycle Raft hour when its in-‘ ventor, Miss Zetta Hills, of London, pushes the pedals Driven by Hand Lever James E. Manvelle, of Wareham, Mass.; has designed a boat that he can propel with one hand while he fishes with the other For Sportsmen A light, unsinkable rowboat for sports- men, invented -in : ~ Germany, is built of two small pon- toons propelled by oars. It can be put together quickly

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A Portable Lighting Plant IGHTING on the farm at a lower cost than the average city rate is promised by the manufacturers of a new automatic portable lighting outfit. The complete plant, exclusive of batteries, weighs only 125. pounds. A small gasoline engine charges the batteries whenever they be- come low. The only attention needed is keeping the engine supplied with fuel. A Round Whisk HISK brooms, ever since the first one was in- vented, have had shapes oth- er than round. This new one, in which the round shape has been adopted, is said to be almost auto- matic in its soft action as it re- volves in the hands of the user. POPULAR SCIENCE MONTHLY m A Picture Gallery Portable Balloon - Rowboat for Mot FIVE-POUND unsinkable boat that may be carried under the arm or under an automobile seat, has proved highly successful in tests on Lake Keuka, N. Y. It is made of goldbeater’s skin, such as is used in the construction of airships, and is built in four compart- ments. Inflation of the new water raft takes only two minutes. It is especially prac- tical for duck hunters or others who need boats but must travel light, as when sev- ‘eral portages occur on a journey. The World’s Deepest Well ‘THE deepest well in the world was com- pleted recently by engineers near faun Pa., when they struck natural gas at a depth of 7428 feet, or nearly 14% miles. Work on the well was begun in 1922, and drilling continued for 30 months. The gas is now flowing at the rate of 500,000 cubic feet a day. It hasa strong odor, like that of hydrogen sulphide, according to the engineers-who constructed the well. The total cost of sinking the well was about $200,000. New Tool Aids Printers in Handling Forms A NEW stereotyper’s and printer’s tool, for use in handling heavy chases or holding forms, is in reality a miniature truck, which can be inserted under one end of the chase in such a way that the weight is carried on rollers, facilitating handling by eliminating the great friction of sliding. The tool consists of a long handle, two rollers, and a hook. It is operated by How the miniature truck carries the weight of a heavy chase inserting this bluntly —_ pointed end or hook in the recess in the chase that rests flat on the table. The tool is then drawn downward and backward, one end of the chase and trans- ferring its weight to the rollers. A really heavy weight can be lifted thus. Motorized Tower Invented for Photographers 7 OBTAIN elevation for the photog. rapher, a folding motorized photo graphic tower has been invented by F, F, lifting - Making a photograph from the tower Huddleston of Los Angeles, Calif. From it exceptionally fine pictures may he taken of street scenes, such as parades. The tower is similar to those used by electricians for repairing trolley wires, but with certain modifications. To keep it from shaking and spoiling pictures, aif plane bracing cables and turnbuckles are > used in constructing the lower part of the tower. In addition, to eliminate spring action, a jack is placed under the truck while pictures are being made. An ingenious crank-and-ratchet mech- anism is used to raise and lower the tower. When driven through the streets, the tower is little higher than the top of the average covered motor-truck.

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March, 1925 POPULAR SCIENCE MONTHLY of New Inventions Western Ranch Gate Opens Automatically N THE Western ranching country where herds roam freely, ‘‘ranch gates” are found frequently across public roads. These highway barriers, which keep cattle or sheep in their proper section of the range, offer no inconvenience to the ranchers who know how to manage them. Portable Shop Is Shaped like a Cigarette THE exterior of this ingenious shop in Berlin, Germany, one of the smallest in the world, is a clever advertisement for the dealer’s wares. A tall metal cylinder represents a cigarette with the upper portion painted to represent a band. A small opening is cut in the center for a counter. The cigarette salesman’s stock is neces- sarily limited by space, but is renewed daily, and the whole shop is portable. It ls set up by the street curbing and is moved according to the state of business. If bumped properly with an automobile, a ranch gate opens automatically, without the driver having to get out of his car. The gate is made of heavy lumber and is swung on an iron pipe in the middle of the road. A gentle bump by an automo- bile pushes it open, twisting the two crossed chains, shown in the photograph, around the pipe. After the car has passed through, these chains untwist and close the gate. A tourist meeting these gates for the first time invariably has trouble. He either strikes the boards too slowly and kills his engine, or else dashes through and feels a resounding smack as the gate swings around too quickly and hits a rear fender. Only after many trials will he agree with the cattlemen that the gates are a convenience. French Plane Has Elevator N AIRPLANE fitted with an ele- vator is being constructed for the French army. It will be used by the gunner in charge of two batteries of ma- chine guns, one at the top of the fuselage, and the other at the bottom. Thus he can pass from one battery to another, as de- sired. 67 theater. Spectacle Opera Glasses (C)PERA glasses used like spectacles end a long-standing annoyance of the In this form the glasses are not easily dropped and the hands are left free and at ease. The lenses of the new invention may be focused separately for each eye, -an ad- vantage to persons whose eyes differ in strength. Easier Window-Cleaning "THE problem of how to clean the outside of a window is solved by a recently pa- tented window, the sashes of which can be swung inward. An additional advantage is that both sashes can be opened at the same time, thus giving double ventilation and turning a bed- room into a real sleeping porch. When installed, the swinging win- dow resembles an ordinary double- hung sash window. Stenographer Invents Handy Type-Cleaner SINGLE push of the typist’s thumbs cleans all of the type on a type- writer without the use of cleaning liquids, by means of a new $33 cleaner invented brush forward over the type. Pushing the cleaner 10 times a day keeps the type in first class condition. by a stenographer. The device is per- manently at- tached. It consists of a brush shaped to fit the are of type on most standard vis- ible machines, and _ is contained in a stamped steel frame. To operate it, the stenogra- pher presses the Pushing the device with the thumbs automatically cleans the type *S8eeros w ee a ae °F

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68 POPULAR SCIENCE MONTHLY A Dozen Woodworking Machines Combined HERE is a new woodworking machine that is said to combine 12 machines in one. It is electrically driven by a 4\%-horsepower motor. It is built in four different sizes and is equipped with a tilting table. Some of the many uses to which it is said to be quickly adapted are stair rout- ing, jack-rafters Bs New Electric Socket Wrench for Automobile Work N ELECTRIC reversible socket wrench, recently invented, is adapted particularly for assembling or disassem- bling automobile motors, and is proving a Driving bolts in auto-cylinder head time-saver in service stations. Work can be done with it in a fraction of the time necessary for doing the job by hand, the inventor claims. The spindle of the wrench is provided with a clutch that automatically releases when the pressure on the tool is relieved. Thus a nut, bolt, or stud may be driven to any desired tightness. For disassembling, a reversing switch is provided. The machine is equipped with a quick- change chuck for holding different sizes of socket wrenches. CHILDREN in darker sections of London are so starved for sunlight that physicians are treating them with arc lamps. Two men use the machine simultaneously for sawing and planing cutting, sanding, plowing, molding, and mortising. It will cross cut up to four inches, rip up to four inches, and cut dadoes two inches wide. THE first airplane to be shot success- fully from an ex- plosive catapult on a battleship, ac- cording to naval engineers, was hurled into the air recently at a speed of 55 miles an hour from _ the U.S.S. Mississippi at the Bremerton Navy Yard, Washington. Although 14 pounds of smokeless powder was used to fire the plane from the forward turret of the battleship, it went on its way without noticeable jerk or shock. be . Se Steel Mail-Safe Invented: for Apartment Houses PROVIDING security for the mail of apartment-house dwellers is this newly designed mailbox, which in reality is a steel safe in the wall. Unlike the old type of mailbox, this is built in a unit with g master door at the top for the postman, who has a key for it. The lower, or individual doors are’ of sufficient height to accommodate maga- zines. The doors are nine inches high and each box is provided with individual lock and name-card holder. Barrels Joined Vertically in New Shotgun © NEW firearm from Europe that is interesting American trap- shooters highly is an “over and un- der” type of double - barreled shotgun. It is a standard 12-inch- gage gun and has been used with great success by sportsmen for hunting and in tar- get matches. It differs from the American sin- gle-barrel trap gun only in the number of its barrels. Its most obvious difference from the regular American double-barre] gun is the posi- tion of the cylinders, which are ‘built one above the other instead of lying horizon- tally parallel. Handy New Soldering Iron A NEW soldering iron has a hollow handle, in which self fluxing solder is kept. The iron is made in the conven- tional shape, and also with the head mounted at right angles for soldering a long seam easily. Trapshooter using the new gun, and view of barrel arrangement Each barrel is 32-inch, full choke, and either can be shot separately. The gun weighs eight pounds and its pattern over a 30-inch circle is 70 per cent at a 40-yard range. Franklin and His Kite F TIMELY interest, in view of re cent doubt cast upon Benjamin Franklin’s kite experiment, is the recent discovery of a letter written by Franklin on the subject in a book published in London in 1774, now in the library of the Franklin Institute, Philadelphia. After describing how to make the kite, with a pointed wire on the upright stick, Franklin says: “As soon as any of the thunder clouds come over the kite, the pointed wire will draw the electric fire from them, and the kite, with all the twine, will be electrified, and the loose filaments of the twine will stand out every way, and be attracted by an approaching finger.” ic BH Peal: FAI z ec aoe | er eee 7, Se ee

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Tiny Air Compressor Runs at High Speed HIS miniature air compressor is one of the smallest practical machines of its kind ever made. Its size and weight are such that it can be held easily in one hand. It is 91% inches high, weighs 18 pounds, and has a piston displacement of three cubic feet. It can make 2500 revolutions a minute, though the normal speed is 1250. One of the many uses for such a small compressor is on an automobile. POPULAR SCIENCE MONTHLY 09 Miniature Castle Is Actual Home for Twa HE smallest livable castle in the world, located in Alhambra, Calif., is occupied by a man and his wife, both of normal size, who, one would think, must find it cramping at second floor are proportionately miniature in size. Guests rarely see the interior of this queer castle. There is no room for them. times. Its proportions were just right for the band of circus Lilliputians who once lived in it, but how full-grown adults can live there is a mystery to those who have seen the elaborate little structure. A comparison with the man of normal size standing in the gateway shows the smallness of the doors and win- dows. The rooms and 2 AE the stairway to the Lilliputian castle in California. Compare it with the man in size A TON of mammoth -tusks taken in Siberian glaciers, and said to be 50,000 years old, were sold recently in England to be made into billiard balls. Smallest Shotgun Is TWENTY-GAGE shotgun reduced to the minimum is owned by Patsy Ruffalo, Jr., of New York, who believes it Fired like a Pistol to be the smallest and most perfect one ever made. Its length is 1214 inches over all and it is fired like a pistol. os + One Eye ONE-EYED fish with ap- parently normal vision has been produced in the ex- perimental labora- tories of the Uni- versity of Chicago, according to a recent announce- ment. In the ex- periment, the eyes of the fish were re- moved, and one was transplanted Breakage Takes the Profit from Egg Shipment THE job of transporting eggs from the farm to the city and country stores so that you may have your supply for breakfast is one beset with extreme diffi- culties, because of the large amount of breakage. For this reason the railroads class the hauling of eggs as traffic without profit. New York City alone consumes 1,800,000,000 eggs a year. The breakage of eggs in transit some- times is due to the character of the shells, which may be too fragile to stand a long journey. Fertile eggs, too, are likely to be smashed on the trip. The annual loss from fertile eggs in the United States is estimated by the U. S. Department of Agriculture to be more than $15,000,000. The railroads have been conducting ex- periments recently to improve meth-ds of shipment. Patsy Ruffalo, Jr., of New York, firing the smallest shotgun into the forehead. This amazing operation was performed by Dr. Theodor Koppyani, famous European eye specialist, and J. Franklin Pearcy, research student in the university, searching for a cure for blindness. Dictionary an Inch Long WNERSHIP of the world’s smallest dictionary is claimed by Peter Gen- kile of Cleveland, Ohio. The midget book, which came from Pompeii, Italy, is only one inch long, three-fourths of an inch wide, and quarter of an inch thick. World’s Smallest Camera for Queen’s Doll’s House AN ASTONISHINGLY tiny camera, hardly bigger than a thumbnail, is complete to the smallest detail, including sede SIR Hardly larger than a man’s thumbnail a crystal lens. It was presented recently to Queen Mary of England by the Kodak Company for her famous doll’s house. When closed, this camera, the smallest in the world, is 1/1728 the size of the camera of which it is a copy. It is only three-quarters of an inch high. Every part was made separately by hand, micro- scopes and jewelers’ tools being used. The process of manufacture took three months in all. Most of the difficulty was given, not by the intricate metal parts, but by the bellows. These, after many experiments, finally were made of paper. New Foe of Mosquito Pest ‘paar the mosquito plague may be exterminated by raising a type of stingless mosquitoes guaranteed to expel the stinging variety was the recent state- ment of Dr. Louis Paul Le Gendre to the French Academy of Sciences. He said the stingless variety thrives in parts of Brittany.

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POPULAR SCIENCE MONTHLY Front-Drive Racing Car—Cliff Durant, American millionaire sportsman and speed king, introduced this revolutionary type of motor-car during recent try-outs for races on the new speedway at Culver City, Calif. The engine is geared to the front axle instead of to the rear, thus pulling the car instead of pushing it Speed in Brickmaking—By a new system of multiple molds (shown at left and in man’s hands), one man, it is said, can cast 4000 bricks a day, thus saving labor and cost rm, Coins of all sizes are pushed into a receptacle, from which they are picked up by a revolving disk device driven by electricity. This carries them along a rack that auto- matically sorts and distributes This Machine Counts Coins March, 1s Unusual New Machines from es eee en Ingenious Mechanical Products Are Pyt Well Drives Mill Two artesian wells from which hundreds of gallons of water gush daily are utilized to run a Georgia sawmill. Natural pressure forces the overflow to a 30-foot water tower, from which it drops through a flume to turn a water wheel 29 feet in diameter He Invents Wind Machine After 30 years’ work, Hyman Rosen, a blind inventor of New York City, has com- pleted a wind machine that he hopes will do away with the need of coal and gas for fuel. The wind-driven vanes that supply the power afe arranged to alter their posi- tions as they revolve, thus presenting their edges when moving into the wind, am thereby reducing resistanee

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March, 1925 Tap’ Does Work of Ten Men A new mechanical marker designed for the id painting of highway traffic lines, is said to be able to mark a 200-foot line, from three to eight inches wide, in one minute equal to the work of 10 men. The machine at weighs 160 fee, pounds and is oper- * ated by one man POPULAR SCIENCE MONTHLY 71 the Workshops of Inventors to Work for Greater Every-Day Efficiency (is Saves Farm Labor — A plow that does the work of ages a breaking plow, pulverizer, 3 yes harrow, and drag, is the recent 1e with invention of William Turner, y for of Chicago, Ill., who got his idea ee from wood-chopping machines Lv po in paper mills. Two rosettes a of steel blades pulverize a ir ye strip of ground 14 inches wide, e, slice the soil and chop weeds 1 Ww = and rubbish into fine pieces sistance 2 {om 4 al PAN? Huge Ditch-Digger Digging 1300 feet of ditch 12 feet wide and four feet deep in eight hours is an ordinary day’s work for a mammoth new 90-ton ex- cavator driven by a 120- horsepower gasoline motor, which recently has proved itself a practical invention on a reclamation project at Albert Lea, Minn. Mechanical Swimming Teacher—On the cushion of this curious machine, the swimming pupil lies with limbs strapped to the device. Turning a handle gives the correct movements Mechanical Sculptor—By means of this newly devised pantograph, E. F. Engleman, an engineer of Hawthorne, II1., creates complete, well sculptured heads from photographs »—> |2

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POPULAR SCIENCE MONTHLY ar Huge Concrete Arch Bridge Built j in 244 Working Days ‘TT second largest solid concrete arch bridge in the world—the Jack’s Run Bridge at Pittsburgh, Pa.—-was com- pleted recently in 244 working days. It is 325 feet long and 170 feet high, and in size is second only to the Cathleen Memorial Bridge at Minneapolis, Minn. Engineers designed the huge arch so that it will compensate for any expansion in bridge span by rising. Engineers Design a Miniature Niagara Falls Two views of the miniature Niagara, constructed to show how the falls may be further harnessed O DEMON- STRATE to Secretary of Com- merce Herbert Hoover and other members of the Northeastern Super-Power Committee that the famous cataract of Niagara may be further con- trolled for power purposes without mar- ting its beauty, a miniature of Niagara Falls recently was constructed in exact detail, on ascale of 100 to I, by engi- neers of the Ni- agara Falls Power Com- pany. Because of the present de- mands of in- dustry on the water supply, there is fear that the falls soon will be an ob- ject of scenic beauty only on Sundays and holidays. The model was constructed to show Secretary Hoover 2nd his committee how this contingency may be avoided by the building of islands and other means. Electricity Milks Cows on French Farms O SAVE French agriculture, which is suffering acutely from a shortage of labor, officials of the government are cooperating with leaders of industry and agriculture to extend the use of cheap electric power in the rural districts. The State is assisting this development by grants and loans to cooperative societies formed to provide local teil eiee electric-supply mains, An evidence of the increased use of electricity in villages is the fact that there are now 302,000 electric lamps, as com- pared with 65,000 in 1919. Electrically operated machines now do the chores on the farm. They milk the cows, skim the milk, and churn the butter. In almost every line of farm work, electricity is doing the work more cheaply than before and in a fraction of the time. This bridge is located on the Lincoln Highway leading out of Pittsburgh to the north. It stands as a monument te modern engineering skill, for within con- siderably less than a year after the first excavations for its foundations were made, motor vehicles were passing across its wide span. The World’s Largest Siphon Built in Washington N AUTOMOBILE could be driven through the world’s largest siphon, which is nearing completion on the out- skirts of Washington, D. C. It is to be used for the Great Fall conduit, which will supply water to the national capital and is expected to be ready for operation in May of this year. The single siphon of gigantic propor- tions is sufficient, in a stretch of 29 miles of piping, to give the water momentum enough to reach its destination. The maximum height to which water can he siphoned is about 34 feet. The mammoth siphen under construction , ge do you want to know? The Information Department of POPULAR SCIENCE MONTHLY will be glad to answer your questions on sub- jects of general science. SAFETY eyes 9( cording sight C

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oln the te On- vere rOss iven hon, out- 0 be hich pital ation ypor- miles itum The n be POPULAR SCIENCE MONTHLY 2 W ORSE than snowdrifts for blocking roadways are the great clouds of sand that whirl over the famed sandhills of Imperial County in southern California. a ¥ ead Portable Highway Defies California Sandstorms Always after such a storm, tons of sand must be removed, or a new roadway laid. Engineers are meeting the difficulty with a portable highway,18 feet wide,made of redwood timbers bolted together. After a severe sandstorm a truck equipped with a crane lifts up a section of the roadway, shakes it clear of sand, and replaces it. Aviator Shoots Photographs from a Parachute NeVe photographers are accustomed to working in dangerous places, but G. A. Shoemaker, of the Army Air Service, is said to be the only one who risks his life regularly by falling in order to take pictures. With three small motion - picture cameras strapped to his belt, and a parachute on his back, this daring photog- rapher, a senior instructor in parachute jumping, leaps from the wing of a Martin bomber. As he falls, he looks about him calmly, taking photographs of bits of seenery or other objects of interest. If the parachute opens properly and he lands safely, he then has for sale several photographs that are of unusual value and interest. Ready to jump from the wing SAFETY methods have cut accidents to eyes 90 per cent in some industries, ac- cording to a recent survey by the Eye- sight Conservation Council of America. p Wy oming Oil Fields oe i Be ae : Bg i et wi ; a Ms ¥ moe: e e oa Map showing route of the 740-mile pipe line from Teapot Dome, Wyo., to Freeman, Mo.; where it will connect with another line running from Houston, Tex., to Chicago, Ill. HE network of pipe lines for the transportation of crude oil—that vast system that covers the eastern part of the United States—is slowly reaching its tentacles westward. Within a year, crude oil from the oil fields of Wyoming will be flowing to Eastern refineries through steel pipes laid underground. There is now under construction a line 740 miles long, which starts in the famous Teapot Dome region of Wyoming, ex- tends across eastern Wyoming, diagonally across Nebraska and Kansas, and ends at Freeman, Mo., where it connects with another pipe line that runs from Houston, Tex., to Chicago, Ill. Through this line, crude oil at the rate of 40,000 barrels a day will flow to refineries at Chicago, Kansas City, or Houston. At the western end the line begins at an elevation of 5000 feet. Within the first 20 miles it climbs to 6100 feet, and from there on it drops steadily to an elevation of 800 feet at Freeman. The drop is almost exactly one mile. Owing to the slow-flowing quality of the oil, pumping stations are required at intervals of approximately 40 miles. Cannon Fired by the Sun Tells the Time “T= only known automatic sun gun in the world, located at Cintra, 20 miles from Lisbon, Portugal, booms the correct time to surrounding towns and hamlets from a height of 2000 feet. By a convex lens arrangement sup- ported by the cannon, and controlled by a sun-dial, the sun’s rays are concentrated at noon each day on the touchhole. of the cannon, .and thus it is automatically fired by old King Sol himself.

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Furniture patcher at work. In front of him is the small cylindrical knife-heater POPULAR SCIENCE MONTHLY Useful Inventions for Electric Heat Aids Furniture Patchers \ Ice Mittens Made of Pronged Metal Plates [c= mittens for conveniently lifting and carrying a cake of ice to the refriger- ator have been devised by Valentine Dexheimer, of Montrose, N. Y. Pair of ice mittens and how they are used Chlorine Bombs Devised for Treatment of Colds OME treatment for colds with chlorine gas has been made possible by the recent invention of a chlorine-gas bomb, perfected by two San Francisco chemists, Paul Richard and A. J. Price. Central agencies for administering chlor- ine gas are found in only a few large cities, and this device is designed to make Breaking the bombs releases the gas the new cold treatment available to every one. The bomb is made of glass and contains pure filtered chlorine gas. The user breaks off the ends of a bomb in a closed room, not more than 12 feet square, and remains in the gas-filled room for one hour, after which time, it is said, unless the cold is deep-seated, the patient feels relief, Each mitten is made of two metal plates hinged together. Small upstanding prongs are punched in the plates to grip the ice. Canvas or leather straps attached to the plates fasten around the hands. The mittens are particularly useful for workers where ice is handled in large quantities. Stoves Doomed? HAT the American coal stove is doomed, and will be supplanted by gas heaters was the recent prediction of W. W. Steere, Detroit engineer, in a report to the American Chemical Society. Losses in American cities from smoke and soft coal run into many millions of dollars annually, Mr. Steere asserted. The increased cost of heating houses and buildings with gas, he added, would be more than offset by the savings to build- ings and their furnishings by the elimina- tion of the smoke nuisance, which does more damage to interiors than exteriors. March, 1925 - (>Pen flame torches recently caused g fire in a large eastern furniture fac. tory, resulting in the death of two work- men. To eliminate this source of danger a new electric furnace for heating the knives employed in patching furniture has been invented. The knives are used for applying stick shellac to cover holes and blemishes, and must be heated to spread the shellac. The small furnace is in the form of an aluminum cylinder mounted by means of two aluminum castings on a finished asbestos base. Each end of the cylinder is open for the insertion of the knives, The furnace is lined with a rust-resisting metal called ‘‘monel.” The photograph shows a furniture patcher at work. In front of him may be seen the electric furnace with knife inserted. : Phone Clip Holds Messages in Plain Sight ELE - cau ty i PHONE | saa messages _ fre- n quently go ey’ ol astray. Writ- ten on a scrap of paper, they often fall to the floor and are lost. This metal clip snaps on the telephone as shown, and - holds the mes- | g@ = sage securely. Superheater Invented SUPERHEATER attachment to increase combustion in furnaces is one of the latest aids in reducing the winter coal bill. The inventor, A. F. Tardie, of Riverside, R. I., estimates that with his new device 30 per cent more heat can be obtained from a pound of coal. Much of the fuel waste in hand-fired furnaces is due to the fact that ‘gases rising from burning fuel fail to ignite because of lack of air, and escape unused up the chimney. Air flowing through the grate is exhausted when it has passed through a few inches of the fuel bed. The new box-shaped superheater ig- nites the gas above the burning coal, by admitting oxygen at a very high tempera- ture over the fuel bed. It is fastened on the inside of the firebox door of the fur- nace. The box is divided into three compart- ments, separated by perforated plates. Air drawn in by the draft enters through a slide in the firebox door. As it passes through the compartments its progress is retarded by baffle plates, thus causing its temperature to increase in each succeeding chamber. It finally passes out in fine streams through a perforated plate, at a high temperature, into the combustion to Save Furnace Fuel chamber, or fire box, of the furnace. Ashes from furnaces equipped with this device are said to be very fine, and practic- ally no wastage of coal passes through the grates. The superheater attached to furnace door wre do you want to know? The Information Department of POP- ULAR SCIENCE MONTHLY will be glad to answer the questions of readers on subjects of general science, — NS’ file ally, headit card S kept i Pus the ft lifts 2 cation contai The anc room | and 01 Atti with : tubing the w serted when With econo guest Visito; box s

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» 1925 - oT eTs Sed g @ fac. work- inger, R the liture used holes ed to of an means lished linder nives, isting niture ay be knife uel urnace, ith this rractic- hrough e door (? The of POP- be glad ders on March, 1925: Home, Shop, and Office Automatic Card Index Is Time-Saver NSTEAD of keeping many separate files for classifying subjects alphabetic- ally, by localities, by industries and other headings, 2 new automatic time-saving card system permits all information to be kept in a single file. Pushing a rod into a numbered slot in the front of the cabinet automatically lifts all.of the cards of a desired classifi- cation above the rest in the file. Each container holds 600 cards. Thermometer Tells Outdoor and Indoor Temperatures NEWLY invented thermometer that A can be hung on the wall of the living- room or in the office registers both indoor and outdoor temperatures. Attached to it is 15 feet of tubing with a sensitive bulb on the end. The tubing is run outdoors through a hole in the window-frame, and the bulb is in- serted in a bracket outside of the building. The top of the thermometer is similar to ordi- nary household thermometers, while the out- door tempera- ture is indicated on a round dial with a pointer. The use of this thermometer saves many a bad cold due to sudden, unreal- ized change in temperature. POPULAR SCIENCE MONTHLY Pushing a d into a numbered slot at the front selects the desired cards Invents a Shockproof Seat for Bicycles Bape and bumps suffered by the rider of an ordinary bicycle injure the spine, declares E. M. Faure of Los Angeles, Calif., who has invented a shock-absorb- ing seat that can be movement. be adjusted. The seat can be attached to motor- cycles as well as to bicycles. The height of the seat- can clamped easily to any bicycle. The springs of the new shock absorber are so arranged that the weight of the rider rests upon the center of the top horizontal bars of the bicycle, thus causing the two wheels and frame to act as a_ bridge over the road’s irregularities. The de- vice also acts ‘as a weight equal- izer, permitting easier pedaling, be- cause the rider’s body rests on the seat more directly above the pedals, and the weight of the body helps to push them down. In the ordinary arrangement, the pedals are pushed almost entirely by muscular leg Rooms Heated Quickly by New Portable Fire ~PORTABLE fire is a recent inven- tion for warming a room quickly when one does not wish to light a coal fire. With it a dining-room can be warmed The heater fits into an open range economically for mealtime only, or a cold guest-room prepared for an unexpected Visitor. The device consists of an aluminum box 80 shaped as to fit into the ordinary open range. It has a lid with handle. The box contains absorbent wool, which, after the lid is removed, is soaked with a pint of paraffin. When lighted, this will give a hot fire for one hour, which is sufficient to warm the average room. When the fire is no longer desired, it is extinguished by put- ting the lid on the box, and the whole thing then can be carried to another room. A New Artificial Wood A REMARKABLE newmaterial known as ‘‘plastic wood” recently has been perfected for such uses as repair- ing furniture, filling cracks in wood, restoring picture-frames and broken cor- ners and filling nail holes or countersunk screws. This artificial wood can be worked and finished with carpenter’s tools, like any lumber. It comes in the form of a thick paste that can be molded to any shape. When exposed to the air it hardens into a tough, waterproof material. This char- acteristic makes it especially valuable for restoring missing parts of any article of furniture. The inventor with his new shock absorber Ventilating Brick Draws Fumes from Kitchen VENTILATING brick inserted in the kitchen wall near the ceiling, as the mason is bricking in, is said to remove all gas fumes, steam and cooking odors from the room, and prevent the walls from becoming discolored. It can be Ventilating brick inserted in the wall used also in pantries, bathrooms, wash- rooms, hung ceilings or closets where air becomes stale or is circulated with diffi- culty. The special advantage of the device is that it takes up no more space than the standard 13-inch brick. The brick is made of cast iron or bronze with a heavy galvanized iron flue.

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POPULAR SCIENCE MONTHLY March, 1995 A Dozen New Ideas Useful Tools and Accessories Invented Extension Light A powerful new type of spotlight is instantly avail- able as a portable trouble lamp, for it has 12 feet of cord on an automatic reel ~ Safety Fender Tested The latest device for protection of pedestrians is a cage fender for auto- mobiles and motor-trucks, demon- strated recently before a group of traffic experts in Washington, D. C, Twin Steering Wheels Jack Neal, an auto dealer of San Antonio, Tex., invented this double-steering-wheel method of teaching how to drive All in One Bag Complete camping equipment, including tent, two woolen blan- kets, rubber sheets, bed- ding roll, two stoves, cooking and table uten- sils, all can be carried in a compact duffle bag at the rear of the caf, as shown in the upper ° P . picture. In addition, it A Windshield for the Sidecar will hold enough Sam Comfort for the passenger of a motorcycle sidecar is for two persons for three provided by a new streamlined windshield that can be Absorbs bumps—Mounted on heavy ordinary sized meals attached in half a minute. The frame of the shield coiled steel springs, this new bumper is can be adjusted to any angle the rider desires designed to take up all road shocks March in evi

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arch, 1925 POPULAR SCIENCE MONTHLY or the Motor-Car to Increase Safety, Comfort, Economy Self Cleaning This screen shutter has been invented to remove pa- pers from racing-car tadiators Removes Papers The screen covering the radiator (above) opens (left) when the driver pulls a_ lever, forcing the papers off | | es WHEY Pe Electrical Chain Hoist For lifting operations in auto-repair shops this electric chain hoist recently ‘has been perfected. Power for the motor is obtained from any electric- light socket that happens to be near Oil pressure is employed for lifting power in the newest type of hydraulic auto jack. When the jack handle is forced downward, oil is forced up from a reservoir, pushing upaplunger. This lifts the load Loads Itself A motor-truck that will load and unload itself by its own power dang invention oe ia - @U.&U. ty) bert C. Stone of a s3 Brooklyn, N.Y. It is ale ; U. S. Tests Brake Linings equipped with a skid * Chie To assure motorists better service from their to move heavy mate- oe _ brakes, the U. S. Bureau of Standards recently fials on and off. By ee began tests of various brake linings used in auto- means of a specially ad- ee »* ci mobiles. Carl H. Roeder is shown with the brake- jJusted automatic plat- ; lining testing machine. While this machine does form, it will handle New Electric Auto Lock not attempt to duplicate actual running con- Successfully face brick ditions, it gives a steady run from which compari- i : An electric lock, recently invented, is nc ca in ’ : , . evenly stacked piles ange see t ressing a butto sons of brake-lining wearability can be made that shuts off the ignition. A switch key turns on the ignition for starting

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POPULAR SCIENCE MONTHLY A day’s catch of “river cows,” or pirarucus, the largest fresh-water fish in the world, found only in the Amazon River and its tributaries Know Your Car AOTOMOBILE springs are built in the form of leaves placed one above the other so that they can slide upon one another, absorbing shocks. Some springs become so rusted that they are practically solid. The effect is as if the car frame were fastened directly to the axles. For riding comfort, springs should. be lubricated at least once in every 5000 miles. Squirting oil along the edges of the springs does little good. It merely acts as a dust collector and little of it seeps between the leaves where the oil is needed. There is a short way to lubricate springs correctly. Put a jack under the frame of the car, not the axle, near the spring that you want to lubricate. Raise the frame until the wheel is free of the floor. When this is done it will be easy to sepa- rate the leaves with a screwdriver. Spread a little cup grease between the leaves with a putty knife, and the job is done. You will be sur- prised at the improvement in your car’s riding qualities. HRILLS and dan- gers, sometimes more. ,than.,are desired, go with catching the pirarucu, the largest fresh-water fish in the world. The sport is re- served for the Indians of South America, for only in the Amazon River and its long tributaries is this giant fish found. The pirarucu, known commonly as the “river cow,” is somewhat like a whale. When fully grown it weighs more than 200 pounds. From the mo- ment it is harpooned it imperils the life of the fisherman. It runs and rushes toward the canoe, threatening to overturn it. Only constant attention and extreme agility on the part of the native keeps South American Indian harpooning a giant pirarucu in the Amazon River Thrills in Hunting “River Cows” the boat right side up on the surface, The boats used for pirarucu hunting are native craft, half canoe, half rowhoat, The fisherman floats quietly in his boat until one of the mammoth fishes rises and begins playing on the surface of the water. Then he paddles stealthily toward the fish, and when he reaches a good pogi- tion, harpoons it. The spear shaft breaks from the point when it strikes the fish, which is held by a cord attached to the point. Then comes a struggle that lasts often several hours. The fish churns through the water, pulling the canoe after it, From shore to shore and many miles up and down the river the angered mammal thrashes, attempting by every means to escape its pursuer. Finally it is exhausted and lies passive. The Indian pulls it alongside the canoe and kills it with his machete. The day's catch is then towed triumphantly home. Lustrous Pearls Made from Fish Scales’ * A remarkable new process, pictured here, artificial pearls now a.e being manufactured from fish scales. These pearls have a luster that makes them almost indistinguishable from the real jewels. Herring scales are placed in a bottle and asecret solution of chemicals is poured over them. These chemicals dissolve the scales and make them into a solution. This is placed in a pan and each beads then dipped into the solution, after which it is set into a rack to dry. The base of the pearl is made of & special smoked glass and is indestructible. Pearls of this type, which are dipped and handled by hand, sell at retail for about $200 a string. Ne\ A C m France and to design has be The ¢ been r fast as water It mount shell is those shape seats t body « the co autom The nary 2 most air-co both « fate Ponte a

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er ” Ss surface, hunting Owboat, his boat ‘ises and of the y toward 0d posi- t breaks the fish, d to the sts often through after it. miles up mammal means to , passive, he canoe ‘he day’s ly home. solution. h bead is ter which ade of @ tructible. pped and for about POPULAR SCIENCE MONTHLY A COMBINATION automobile and motor-boat, invented recently in France, is of great interest to sportsmen and tourists. Unlike many types of craft designed for both land and water, nothing has been sacrificed in its construction. Te complete mechanism of each has peen retained. On land the car travels as fast as the average automobile, and in water it is a speedy power boat. It consists of two parts—a chassis mounted on wheels and a shell. The shell is made of steel plates in imitation of those often used on ships, and has the shape of a canoe, with two passenger seats that can be raised or lowered. This body contains both sets of machinery and the controls necessary to run the boat and automobile. The motor is similar to those of ordi- nary automobiles and also those found on most small power boats. The engine is air-cooled and the steering-wheel serves both car and boat. How the machine appears on the road when used as a motor-car New French Car also a Power Boat When an automobile the owner merely mounts the shell, by means of jacks, to the proper position on the To remove the shell, when the machine is to be used as a boat, is said to be even easier. is desired, chassis. A NEw light - weight steam-power airplanes and vented recently by H. Crossland Pfaff, 2 New York mechanical en- gineer, soon tested by the govern- The engine is said to burn crude ment. motor for autos, in- may be oil, and the inventor claims it is capable of developing one horsepower a pound. If it proves equal to such performance, according to experts, it will be the great- est motor in the world. cee — [% THE Culver City Speedway classic at Los Angeles not long ago, the world’s record for automobile racing was smashed by more than eight miles an hour. After the race, interested spectators gathered to examine the device largely responsible for the terrific speed of the ctars—the supercharger. Mounted at the side of the engine, Speed Records Broke lil ene n with Supercharger the supercharger forces an extra charge of gas into the cylinders. It is the in- vention of Fred Duesenberg. THE next radical development in the modern closed car, according to recent predictions, will be glass or celluloid sides and tops to give passengers an unob- structed view of the scenery. i The same machine transformed into a speedy power boat, driven by the same engine but with a canoe-shaped steel shell attached to the chassis How Much Science Do You Know? ee the following questions to the best of your ability, then turn to the correct answers on page 169 and see how nearly you were right. 1. What is the coldest thing in the world? 2. How much water is there in the sea? 3. Is the ether a real thing? 4. What things in the blood have the duty of destroying germs? 5. How strong does an electric current have to be before it will cause death? 6. Why does soap help to re- move dirt? 7. How do we know that plant seeds are alive? 8. Are all the planets solid? 9. How do arteries differ from veins? 10. Are white people more like the yellow race or more like the negro race? 11. What rare metal is used on the tips of fountain pens? 12. How much real power is there in a radio wave?

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POPULAR SCIENCE MONTHLY March, 1995 eae PATROL planes capable of an entire day’s flight without landing, with a speed of more than 100 miles an hour, and with tremendous cargo space, are the latest type of naval flying boat. The PN-7 shown here has established seven world records and broken three for per- formance by seaplanes carrying heavy loads. It has twin Wright engines and carries New Patrol Plane Establishes Seven World’s Records a crew of four men. Its tanks hold 489 gallons of fuel and the plane attains a maximum speed of 105 miles an hour. It has carried as great a weight as 16,500 pounds on a trip. Great importance is attached to the value of this type of plane in possible sea warfare. With their wide cruising radius, they could meet surprise attacks from a long distance. They could hop off un- Ingenious Wind Motor A WIND motor generator producing an unusually large amount of power is the invention of L. Suter of West New York, N. J. It consists of two separate windmills with vertical planes that are set on opposite sides of a large hoop. The entire motor turns on a track so that it faces the wind. A wedge-shaped piece of wood between the two windmills splits the air into two parts, thus making each current turn a windmill. Gearings at the top of the device transmit the power generated by the two mills to the main driving shaft. Plane Hooks Up to Airship PEEDING at 53 miles an hour above Scott Field, Ill., recently, a Sperry messenger plane hooked itself to the army dirigible TC-8, traveling at the same speed. This remarkable feat was accomplished by means of a metal hook above the motor of the plane which caught a trapeze swinging beneath the airship. Tall Trees Are Transplanted Successfully CONTRARY to tradition, full-grown trees may be replanted successfully. A recent invention of a large Eastern nursery has made this pos- sible. Large ever- green trees must be dug with a ball of earth around the roots. A lacing is placed around the ball to hold it securely and prevent breaking. A large steel platform is then slid under the earth and fastened. The tree is skidded up on a steel truck and tilted over, as shown in the illustration, so that it can be transported through streets. In planting, the truck is hauled to the edge of the hole, the tree tilted up- right, and skidded into the hole. After the tree is in the hole, the platformis pulled out fromun- der the earth ball. Deciduous trees are dug with bare roots, or with a small ball of earth in the center and roots extending. - a less painful process. supported from San Diego, Calif., for Honolulu, thence to the Philippines, As coast cruisers they have constant useful- ness. Further developments in this sort of plane are being embodied by the Navy Department at Seattle, Wash., in a new plane. This will be capable of making 2500 miles in non-stop flight and carry a full load weight of 24,000 pounds. Toy Hides Camera Lens and Insures Child’s Interest BETTER than a rabbit or jumping monkey is this toy house, which a Cincinnati photographer, J. Anthony Bill, places over his camera lens while photo- graphing small children. The - child watches the little front door of the house. At any moment something may come out of it. The photograph records an expres sion of interest and expectancy. Lenses that reflect light glaring forth from folds of black cloth are terrifying to many small children. This new device covers the lens and makes picture-taking rr a ee ee ee ee a |

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and ast mping hich a y Bill, photo- child house. me out >xpres- y forth rifying device taking March, 1925 College Professor Invents an Au POPULAR SCIENCE MONTHLY pass implements run by machinery were curiosities only a few years ago. Now inventors are going further and seeking to perfect farm machines that will run by themselves. One development is along the line of radio control of machin- ery, as described elsewhere in this issue; another has to do with the invention of purely mechanical automats that will turn corners as carefully as if guided by human hands. In the photograph is seen an auto- matic plow driven by gasoline, invented by Prof. J. B. Davidson, head of the Agricultural Engineering Department of Iowa State University. All the farmer Folding Clock Devised by California Inventor ARCEL MOREAU, inventor of a furnace that makes synthetic jewels from powders, has a hobby for making cfocks in his spare time. One of the most curious of these is the folding clock shown in the photograph. It is two feet in diameter when opened, and folds into the small box the inventor is holding. The clock weighs only one pound and is so finely balanced that the large hands are run by the mechanism of a dollar watch placed in the center. The odd timepiece is stem wound and set. When the inventor travels, he car- ries it with him instead of an alarm-clock. Unique Machine Threshes Melons for Seed HRESHING muskmelons and canta- loupes has been developed into one of the most important industries in south- western Kansas—that of supplying melon seeds to large seed firms throughout the United States. For this the melon-growers have devised a unique thresher, driven by a small gaso- line engine, and mounted on a horse- drawn truck. The gathered melons are thrown into the hopper of the machine, where knives slice them as they fall into a conveyor that carries them into a revolving mesh reel. This separates the pulp and rinds from the seeds. The rinds, dropped from the machine, are used later as a winter feed for live- stock. In further processes the seed is cleaned and dried for shipping to various sections of the country. tomatic Gasoline Plow need do, it is said, is to wind up the mechanism and plow one furrow by hand, as a mark to govern adjacent furrows. The machine then will do the rest. The inventor believes this machine will reduce greatly the yearly cost of plowing in the United States, now estimated at $150,000,000. New Ball-and-Socket Joint BALL-AND-SOCKET universal joint by which the piston rod of a gas engine is connected with the piston head was recently invented by John B. Hum- pert, of San Francisco. The head is said to adapt itself readily to any fosition, always in perfect alinement with the cylinder. An important feature of the invention is that no crankpins are necessary. Architects Send Sample Houses by Truck LEVER ideas in advertising have boosted the real-estate business re- cently in London. One enterprising firm there has built a model house, complete in every detail, on a truck that carries it to the door of the prospective customer. Another scheme is that of selling houses by mail. This is an idea of a London inventor, Mr. Partridge. You can choose clothing, food, and furniture from samples; why not houses? asked Mr. Partridge, who re- cently applied his idea. Exhibiting a model house, mounted on a motor-truck, to prospective buyers He makes small model houses, com- plete in every detail, for architects, who send them to _ prospective clients. The prices are at- tached, and if the prospect is suited, he orders his plans. ne

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POPULAR SCIENCE MONTHLY

Scraper and scrubber for vegetables are combined in this handy utensil with blade on one side and brush on the other March, 1925 New Utensils to Inventions Designed to Save

Jk Improved Can-Opener. This tool differs from the ordinary can- opener in that the cutting blade points inward. handle of the opener cuts the tin Pulling up the

A clothes-drying rack can be improvised quickly with a new metal clamp that holds a set of hooks tightly to the radiator

Propeller Egg-Beater. Two eight-bladed pro- pellers, rotating in op- posite directions, pro- duce a churning motion that beats the eggs very quickly. The propellers

Scrubbing-brush, mop, and wringer are attached at the are combined in this useful new device for bottom of a shaft that is cleaning. The mop is held in wooden geared to the drive wheel rollers. Brush or mop may be removed

Lifting the cap of a milk bottle is simplified by this metal lid with spiral knife. After the lid is pressed down, a twist and a pull remove the cap readily

Fuel economy is claimed for a new type of rapid gas-cooker with double burners. A smooth metal disk set above a corrugated disk over the gas out- let produces a strong < double circle of flame

A pot-scraper with steel mesh attached is one of the newest devices for cleaning dirty pots and pans. The sharp scraper is particularly useful for removing food that has burned to the pan

5 Gee gt ty | atti

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a “A yottle al lid ne lid ind a adily with ched west ning ans. er iS il for March, 1925 POPULAR SCIENCE MONTHLY 83 Help the Housewife Time and Labor in the Home eee wt ey A new glass rolling-pin has one end open so that it may be filled with ice-water for pastry making An adjustable grip arrangement removes the top from any size of jar. The handles form bottle and can openers, as necessity requires For the bathroom, the newest convenience combines a compact cabinet and table, containing shelves for medicines and toilet articles, a series of drawers, a waste basket for soiled towels, and a sliding cabinet for shoes and slippers. The entire cabinet oc- cupies only 22 by 17 inches of valuable bathroom floor space A new bottle stopper is au- tomatic in action. When pressed down, spring clamps hold it tightly. The stopper is removed by slight pressure Fireproof — One of the newest inventions for the electric iron is a steel fireproof case into which the iron can be placed after use. The case keeps it clean and dry and out of harm’s way Cooking without water is said to be possible with a new type of aluminum No stirring of cooking food is required, it is triple-bottomed pot. claimed, when this plate is placed between the A tight-fitting top pot and gas flame, because the plate contains prevents the escape a double air chamber which distributes the heat of moisture given off evenly, making it impossible for more heat to by the cooking food accumulate at the center of the pot than around the sides. Waste of fuel and the danger of boiling over thus are prevented

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84° a POPULAR SCIENCE MONTHLY A Fascinating New Way to Plan a Home March, 1925 Architect’s Ingenious Cut-Out Method Is like a Game By G. Gouverneur Ashwell NE of the dominating 6) American emotions is love of home. Most of us have mental pictures of the homes we hope one day to build. We may be a little vague as to detail, such as the exact size of the living-room or the location of the fireplace, but nevertheless the avet- age American has a rather well defined idea of the kind of house he wants most. You probably have made rough sketches of the home you want to own—sketches that outline in general your ideal house, but which, due to your lack of experience in architectural design, fail to show the very detail that is to make yourhomedifferent. Here, then, for the first time, is your chance to design your ideal home to the last detail so far as proportions, locations of doors, windows, pillars, stairs, kitchen, furniture, fireplaces, bathroom fixtures, and the like are concerned. The architectural de- tails have been worked out for you according to scale on pages 86 and 87. You can devote your time to arranging them in the most artistic and prac- tical manner. All you will What do you like best about this English dwelling? Study the floor plans Your Dream Home on Paper ERE Mr. Ashwell, a well known New York architect, outlines an ingeniously simple way to put on paper dream homes such as most of us have tucked away in the back of our heads. For the first time the layman is offered a practical, workable way to plan his home in detail and to accurate scale. Read the article carefully. Next, study the plans shown on this page and on page 85. Then put your scissors and paste to work on the cut-outs shown on pages 86 and 87. If you wish, you may send tracings of your plans to The Editor, Poputar Science Montuty, 250 Fourth Avenue, New York. Accompany them with a stamped self-addressed envelope, and they will be returned with architectural criticisms and comments. Then you will be ready to consult your own architect, with- out whose advice you should not begin construction. An Attractive English House Fully Expanded need in addition to dia- grammatic units represent- ing the walls, windows, and other items shown in this article are a large sheet of one - fourth-inch crogs- hatched plotting paper, a pair of scissors and a paste- pot. The cross-hatched pa- per can be purchased at most stationery stores, or you can make it yourself, It should be about 22 inches by 30 inches to give you plenty of room to work. The squares should be one- fourth inch. F YOU want to make the cross-hatching yourself, simply rule off 55 parallel lines one-fourth inch apart one way and 865 lines at right angles to them on a blank piece of paper of 22 by 30 inches dimension. This paper will be your workbench. Mounted on some stiff base, such as wall- board or other heavy cardboard, it will serve as the plot on which you will build your dream house. Now you are ready to lay out your house. Remem- ber, though, that your designs will not be finished drawings from which a_ house can be _ built. They will be what an_archi- tect calls ‘‘pre- liminary sketch- es,” that show your ideas “in the rough.”’ No Future butler’s pantry, 8'0'' by 8'6". I—Future dining-room, 18'0" by carefully for ideas. This dream house has been expanded from the small 20'0"'". jJ—Future garage, 12'0'' by 20'0"'. K—Future covered porch, house plans indicated by the heavy black lines in the floor plans shown 11'0" by 20'0". L—Vestibule, 4'0'' by 5'6'"". M—Rear porch 4'6" by in the illustration above. The first-floor plan (left) contains: 8'0". N—Range. O—Sink. The second-floor plan includes: P—Bedroom, A—Inglenook, 4'0"' by 8'0"', with fireplace and seats each side. B— 12'0"' by 13'6''. Q—Bedroom, 11'0"' by 14'0'"'". R—Bedroom, 12'0" by Living-room, 16'0"' by 27'0"". C—Living-porch, 12'0"' by 16'0". D— 14'0"'", S—Bedroom 12'0" by 12'0"". T—Future bedroom, 16'0"' by 18'0". U Toilet, 4'6"' by 5'6"'. E—Coat closet, 2'0"' by 5'6'"". F—Present dining- | —Bathroom 7'0"' by 9'0" and 4'6" by 5'6"'". V—Stair hall, 7'0"' by 19'0". W room, 12'0"' by 12'0" (future den). G—Kitchen, 12'0" by 14'6". H— —Future bathroom, 8'0" by 8'6"'". X—Closets, 2'0" by 4'0" or 2'6"' by 3'6" > ee 62lCU eee [lee eee 7 we

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he lel art la of on. ch. all- uild our em- shat will hed rom use uilt. -chi- pre- teh- how “in No March, 1925 A Spanish House Full of Interesting Ideas If you study the arrangement of this Spanish type house ou will find many interesting features that you may wish c incorporate in your own plans. This house, too, is capa- ble of expansion as future needs require. The plans for the first floor include: A—Living-room (two stories high), 18'0" b 20'0''. B—Bedroom or future dining-room, 14'6"' by 16'0"'". C—Kitchen, 11'6"' by 14'0". D—Dining alcove, 9'0"' by 10'0"' (future den or sewing-room). E— Loggia or porch, 8'0" by 18'0''. &—Future bedroom, 12'0"' by 12'0''. G—Future hall, 3'6" by 11'0". H— Future bedroom, 12'0'"' by 12'0''. J—Future bathroom, 6'0"' by 7'6"'. J—Future coat closet, 3'6'' by 6'0". K— Terrace or porch, 7'0'' by 10'0''. Closets, 2'0"' by 4'6". The second-floor plan contains: A—Upper part of living- room. L—Balcony, 3'6"' by 20'0"'. M-—Bedroom, 14'6" by 16'0"'. N—Bedroom, 9'0" by 12'0''. O—Stair hall, 3'6" by 7'0''. P—Linen closet, 4'0'"' by 4'6". Q—Bath- room, 9'0'' by 9'0'". R—Closet, 3'0"' by 4'6'"'. S—Closet, 2'0" by 4'0". T—Closet, 1'6" by 5'6"' puilding operations should be undertaken until a com- petent architect works out the detail drawings and specifications. But these preliminary sketches should give your architect an ade- quate understanding of your ideas and should save you a great deal in construction charges. IRST of all, study the sketches and floor plans shown on these pages. They will give you an idea of how to lay out your house. These plans represent three POPULAR SCIENCE MONTHLY Plan of first floor Plan of second floor of the most popular types of architec- ture—English, Spanish, and Colonial. They are flexible, being capable of ex- pansion without much alteration when more room is needed. The accompanying sketches of the finished houses show them as they will appear when all additions are made. In the floor plans the original house is shown in black lines, and the additions in designed originally to accommodate com- fortably a family of two or three, and later extended as the family grows or as finances permit a larger house. You may want to model your house after one of these plans, changing it, of course, to suit your par- ticular needs. But the plans are shown primarily to guide you in laying out your own plans, no matter what they should happen to be. You may have altogether Now, make a number of rough sketches of your home, until you get definitely in mind your general floor plan. Then make amore finished freehand sketch that will serve you as a model. Next, cut out the long black strips shown on page 86. These represent walls and partitions, and may be cut to any length desired, each quarter-inch representing a foot in your walls. light lines. Any one of these housescan be different ideas of a home. of first floor With four pieces of the walls form one This Colonial Plan Suggests Many Conveniences In a roomy Colonial house such as this one, you will find many advantages and conveniences that you can adapt readily in laying out the plans for your ideal home. The arrangement, too, adapts itself readily to future expansion. A—tThe present living-room, 16'0" by 18'0'', can be con- verted into the future dining-room. B—Living-porch, 12'0"' by 20'0'', becomes a future garage. C—Dining alcove, future butler’s pantry. D—Kitchen, 12'0"' by 12'0"". E— future living-room, 18'0'"' by 25'0". F—Pantry. G— Range. H—Closet. J—Sink. J—JIcebox. K—Rear porch. 2Z—Bedroom, 13'6'' by 18'0'"'. M—Bathroom, 8'0" by 12'0''. N—Bedroom, 9'0"' by 12'0''. O—Future bathroom, 8'0"' by 8'0''. P—Linen closet. Q—Closet. R —Closet. S—Closet. TJ—Future bedroom, 12'0'"' by 15'6". U—Future bedroom, 12'0"' by 15'6'"'. V—Closet. W— Closet. X—Closet. Y—Roof. Z—Roof. Plan of second floor ee

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86 Here Are Your Walls, Columns, and Windows POPULAR SCIENCE MONTHLY COLUMNS, POSTS, WALLSw* PARTITIONS i019 1g 17 16 IS 14 13 12 I 38 137 136 135 134 [33 132 131 130 129 128 127 '26 125 124 123 122 '21 120 NS NB 7 Ne WS M4 113 H2 PIERS, JAMBS WINDOWS | z Kk 2-0 > = 2s 2 2 6 KI 4 _—_a Ea 20d E-—5 6 >| K 2 _s : ; 4 6 > K2 e e 4 & € z Lo "| k bs be 2-6" 2 Et Ea 2 * a | 5 4 yS-o 5 a a i How to Use the Cut-Outs After you have studied the designs of the three popular types of homes on the preceding pages and have formu- lated in your mind a fairly definite idea of your ideal home, you are ready to lay out your floor plans on a defi- nite scale of measurement, using the cut-outs on this and the opposite page. The thick, black lines are your walls and partitions, which you can cut to any required lengths, remembering that each quarter of an irich represents a foot of your walls. The columns, posts, piers, jambs, windows—in fact, ell the cut-outs on these pages—repre- sent standard sizes measured accurately to the same scale—one-quarter of an inch representing one foot in the finished house. To “build” your rooms, you arrange these cut-outs on quarter-inch cross-hatched plotting paper. In this you will be guided by the fact that each square of your paper represents a square foot of your house and that each side of a square isa lineal foot March, 1995 room of your plan by pinning them to the plotting sheet. Determine dimensions from the squares on the plotting sheet (one side of any of these squares repre- sents a foot, and the square itself a Square foot). Then, in like manner, lay out the other rooms, shifting about walls and partitions until you think you have what you want. With the walls temporarily pinned to the plotting sheet, the next step is to locate windows and doors. Doors are indicated by leaving an opening in your wall or partition. Closet doors require a space of 2 feet 6 inches: room doors, 2 feet 8 inches, or 2 feet 10 inches; exterior doors, 2 feet 10 inches, or 3 feet, or 3 feet 6 inches; double cage. ment doors from 4 feet to 5 feet. ON THIS page you find a selection of windows of various sizes. Cut out the sizes desired for each room and pin them on the wall strips where desired, with some thought as to how they will look on the outside wall, and as to how furniture will be placed with relation to them. Don’t paste anything yet. Now for the final details of design, Starting with the living-room, pick out a fireplace of the right size from -the illus- trations on page 87. You may have one or more fireplaces in your house, if you de- sire. Try to keep the kitchen range near a fireplace so that only one chimney will be required for both. Now place the heater flue so it comes in the same chim- ney. Bear in mind that flues and fire places must have eight inches of brick on all sides or between flues and fireplaces. When you have your fireplace in posi- tion, check up and see that it is located to allow the correct wall space for book- eases and other built-in features, and also that it is in the proper location with rela- tion to windows and doors. If you con- sider the room well balanced, you may leave it as it is; but if the fireplace seems to be out of position, you can move your windows, doors, or the hearth itself to get the arrangement you want. After you have laid out the rooms on the first floor, arrange your furniture in them as a final test of their correctness of design according to your needs. You can do this by drawing small squares, circles, and various shaped rectangles on a scale one quarter inch to a foot to represent your piano, davenport, upholstered chairs, ete. If you find your windows are too close together to allow placing the daven- port between them, for example, or that your doors interfere with the placing of other pieces of furniture, it is an easy matter to pull out the pins and rearrange a detail here and there. In the kitchen place your sink, range, icebox, cupboards, and other necessary furniture, using the cut-outs on page 87. You then will be able to decide just where you want your light plugs and where you want your doors. Ts matter of providing correct space for furniture and fixtures is an eX- tremely important one, especially if you plan to use your present furniture in the ideal home you are planning. Measure each piece of furniture carefully, and after you have prepared a paper unit cut to scale, try placing it in various parts of the room to see where it will be most convenient and where it will present the a> eee ak em [06 oe OU|[ ee eee OC cece, Oo hi — sa = Fs ys pm oOo @® fee for pla If cut the inc qui

Page 55

re he nd at ion out pin red, how 1 to ign. ut a llus- one 1 de- near the him- k on aces. posi- rated 00k- | also rela- con- may seems your elf to ns on ure. in ess of yu can ircles, . scale resent chairs, re too javen- yr that ‘ing of 1 easy rrange itchen yoards, ng the will be it your - doors. t space an ex- if you . in the [easure y, and init cut s parts ye most ent the

March, 1925 best appearance. Many a new home, otherwise attractive, has been spoiled simply because the furniture would not fit into it properly. After you have completed the first floor of the house, lay out the second floor on a piece of tracing paper, to con- form with the design of the ground-floor plan. Remember that houses need clos- ets. In laying out your upper floor, your architectural ingenuity will be taxed to get enough closets and at the same time keep them from taking up too much room space. They may be set to good advan- tage between two rooms, each room taking part of the space. Also the space under stairways may be utilized for storage closets. N LAYING out your bathroom be sure I to place your window, if you have only one; to the best advantage. This should be placed so that the light will fall on you when you shave and at the same time light the rest of the room. The bathroom fixtures provided in the cut-outs can be arranged to suit the particular size and shape of your room. Tubs come in sev- eral sizes and shapes. Washbowls also offer a wide selection. On another piece of tracing paper lay out your cellar. The stairs should come up under the stairway leading -to the second floor. Put your furnace near the same chimney that is intended to serve your fireplace and kitchen range, unless you want two chimneys, and make allow- ance for the convenient location of the coalbin and ash receiver. And don’t for- get to provide for an entrance from the outside. If you desire, a separate room can be marked off for storage of canned fruits, vegetables, and the like. If you intend to place your laundry tubs in the basement, put them as‘far away from the furnace as you can. A separate basement room is desirable for laundry work. ener original house should have one bathroom, one living-room, and one bedroom at least; also space for stairway to second floor and stairway to cellar. Many houses appear to be awkwardly cut up because the stairways are not conve- niently placed. In a Colonial house with a hallway, the placing of the stairway is a simple matter. There is no place but the hall for it. But in houses that have no hall the stair should be made to fit in as part of one of the rooms. The living-room usually is the place selected for the stair. Some attractive effects can be got by bringing the stairs down in artistic turns. The stairs shown on this page represent a standard size. They have a seven-inch rise and a 10-inch tread, are fairly easy to ascend and are in general use. A six-inch rise and 12-inch tread make easy and attractive stairs. There are, however, other standard widths for stairs that you may use if you like, ranging from 21% feet for cellar and attic steps to 4 feet for main stairways. If you use a platform where your stair turns at right angles, the platform takes the place of one tread. If you turn with winders (shown in the cut-outs), each group of winders takes the place of three treads. For the seven- inch step, 17 risers or 16 treads are re- quired to reach from first to second floor. POPULAR SCIENCE MONTHLY FIREPLACE FIREPLACE

87 Here Are Your Fixtures, Chimneys, and Stairs

FIREPLACE

L| CHIMNEY

CHI NINEY

——.. )

KITCHEN SINK

food)

ICEBOX

CUP BOARDS [COUNTER WITH CUPBOARDS UNDER | | |

ar ET

BATHTUB

~ BATHTU a

=

Pe aie,

CF) 2 <= TOILET

STAIRS

No matter how you arrange them, the rises will be the same. You can build the stairs to suit your design, cutting up the flight in sections and inserting winders or platforms where and as you choose. When you have completed your design and have decided there will be no more changes, then paste all walls, windows, flues, and other stationary fixtures in place. You then will have a complete preliminary plan from which any ar- chitect could work out specifications and working drawings for the home of your dreams. The entire process, from cutting out the units of the floor plans and arranging them in various schemes to measuring and fitting in your furniture to the best advantage, you will find as entertaining and fascinating as a parlor game. If you encounter difficult problems here and there, don’t be discouraged. That is part of the game. And in the end you will have created something of real value to yourself.

How Well Can You Fit Them In? Now comes the final test of your ingenuity. -How accurately and _ skilfully can you cut and fit these fixtures—stairways, win- dows, cupboards, fire- places, and all the rest— into the rooms you have laid out on your plotting paper? All these cut-outs, like those on the opposite page, represent standard sizes drawn accurately to the scale of one-quarter of an inch to the foot. You will find it really fascinat- ing to arrange and re- arrange the cut-outs until each wall, window, fixture, and piece of furniture fits accurately in the exact place that pleases you most. If you should spoil one of the cut-outs or should require additional units, you can easily make extra ones, using these as models for measurement

STAIRS

jhe eee Cakes en eS

tld ut

Page 56

REG OE A Chauffeurless Auto Pedestrians and motorists in London re- cently were mystified when this small car, without a driver or any visible means of control, threaded its way at fair speed through the traffic of Piccadilly Circus. Before long, Commander Green predicts, a business man, after driving to his office, may send his automobile back home by radio By Lieutenant-Commander Fitzhugh Green, U.S.N. T X yITH the advent of a successful gas engine 25 years ago came a myriad of automobiles and many thousands of airplanes. Gas engines brought cheap light and labor to the farm and swift transportation to the city, changing the lives of millions for the bet- ter. Now the second quarter of the cen- tury opens with a mechanical marvel that bids fair to outstrip even the gas engine in its profound effec’! --» human existence. This marvel is radiodynamics—or, in simpler terms, the science of remote control of motive mechanism by means of radio. There is no great novelty about radio- dynamics. We hear little of this curious branch of radio engineering principally because all forms of wireless communica- tion, especially broadcasting, have so strongly gripped the popular imagination. More than a quarter of a century ago an Englishman patented a scheme for wire- less guidance of a self-propelled boat. In the past 10 years Nikola Tesla and John Hays Hammond, Jr., have built similar devices with complete success. In the military world radiodynamics already has reached a practical stage. British and American navies both control crewless target vessels from a distance. A year ago the old U.S.S. Jowa fought ¥ , TSAR Oh. POPULAR SCIENCE MONTHLY under such conditions. Radio-controlled submarines and torpedoes have been developed. On March 7, 1924, Captain Murphy, U.S. A., directed the first pilot- less airship in this country at McCook field in Dayton, Ohio. On November 9, 1924, press announcements were sent out describing the perfection, by a famous Italian inventor, G. Fiamoa, of a radio device that directed the movements of a distant, rapidly moving submarine chaser, despite the most violent efforts at interference by shore stations. N ALL such automatons the motive power is_ self-contained. Radiant energy in large amounts is not yet prac- tical. Gas, steam, or compressed-air engines drive the vehicle or vessel that is radio-controlled. All that radio does is to steer. To understand more clearly the present circumstances surrounding radiodynamics it is worth while to glance for a moment at one or two outstanding facts of electrical development. In 1727, Stephen Gray, of London, astonished the world by passing an electric current over 700 feet of wire. But it was not until 1836 that Morse con- structed his first telegraph. Note that he did not invent it. Rather should we say that he added a final touch to the com- March, 1925 Radio Control—the You May Live to See Airplanes, Ships, her last action with our Pacific Fleet bined efforts of the many deep-thinking scientific men who preceded him. The art of distant control of mechanism by wire-carried current is technically known as “‘teledynamics.” The great ob. stacle to the early development of this art was exactly that which now besets radiodynamics: not enough electrical energy survived at the far end of the sys. tem to do any useful work. It was only mankind’s vigorous demand for teleg- raphy at a great distance that finally brought about the invention of the “relay.” A relay is a very sensitive but simple form of electric lever that responds to cur. rents almost incalculably weak. It is the keynote of success for all systems involy- ing the distant control of mechanisms. In wired systems it has enabled the mere pressure of a telegraph key, through which a few thousandths of an ampere flow to a distant relay, to start or stop the most powerful machinery, or to set off vast charges of explosive. Such mechan- isms as electric bells, fire alarms, electrie clocks, and telephone signals all are sam- ples of teledynamics. S SOON as wireless systems came into use, inventors began experi- ments to find out whether relays couldn’t be operated by radiant energy. Not only Farming by Radio

ception of the farmer of the future cultivating his fields by radio. Resting comfort- ably in a cool control tower, he merely touches switches to make tractors obey his will Commander Green’s con

: Au electric ether V ment 1 develo} for de blentz Washil eter,” the he tance ¢ he tern a pers! percep his fac such ir ing sig dering dealing yd eal graph radiant tivenes receivi in the transm the ap one ter ever re Suck adequé well m an im] than ¢ best re ably ¥ than « thousa telephe situate able vi has to not of radiati for or: comm< etticien dynam How handic and su trol in So far have 1 they a time, |

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sm lly db- art ets cal ys- nly eg- ully the ple ure the oly- In ere ugh ere the off lan- trie am- ame eri- dn’t only lio of the fields afort- ower, tches is will March, 1925 arvel of the Future Governed by Wireless = Autos, and Tractors i cillations, but other forms of ee vere were used. Great encourage- a was given a few years ago by the gevelopment of highly sensitive devices for detecting heat waves. Doctor Co- plentz of the Bureau of Standards in Washington contrived a ‘*microradiom- eter,” as he called it, that would detect the heat of an ordinary candle at a dis- tance of 58 miles! Edison produced what he termed a ‘“‘tasimeter,’’ so sensitive that a person 30 feet away could produce a perceptible effect on it simply by turning his face toward the instrument. From such inventions rose wild stories of read- ing signals from distant stars and of ren- dering an enemy helpless by “‘death- dealing rays.” UT the same trouble that baffled B early attempts to perfect the tele- graph still stood in the way of utilizing radiant energy—despite marvelous sensi- tiveness, not enough energy reached the receiving station to do any good. Whereas in the wired telegraph it was possible to transmit at least one-thousandth part of the applied power, in radio only about one ten-trillionth of the current sent out ever reached the receiving station. Such minute quantities of current are adequate to make signals so audible that a well made telephone will respond under an impressed electromotive force of less than one-millionth of a volt. But the best relay that ever has been built prob- ably would not trip with anything less than one thousandth of a volt, or a_ thousand times as much energy as the telephone needs. And when this relay is situated in a plane or ship, the unavoid- able vibration is so great that the device has to be made much stiffer so that it will not operate without pressure from the radiating station. Thus, a receiving set for ordinary signals or broadcasting is commonly considered about 5000 times as elficient as one intended for use in radio- dynamics. However, despite this tremendous handicap, there really has been a rapid and successful development of radio con- trol in the past few years. So far, distances involved have not been great; but they are increasing all the time. Marconi, for instance, POPULAR SCIENCE MONTHLY predicts a range of more than 1000 miles for pilotless planes within the next few years. The principle of radio piloting is very simple to understand. A human pilot or a helms- man pushes his rudder to left or right when a tiny spark of infinitesimal mental energy releases the waiting power stored up in his obedient arm. Radiodynamic control is exactly like that. A small motor or compressed - air cylinder, corre- sponding to the helmsman’s arm, is connected with the rudder. A very delicately balanced electri- cal relay releases this mechanical ‘‘helmsman’s arm’”’ when it receives the incoming radio impulse for which it is tuned. Such an impulse is analogous to the mental will power dart- ing by way of motor nerves to the human arm. Radiodynamic control is exercised in a variety of ways, all of which fall into one of two classes: Either there is a separate receiving set for each steering unit or there is a selector system like that used for our automatic telephones. N EITHER system the automatic boat, tank, torpedo, or plane is re- leased from human control with engines running and rudder amidships. If the automaton is to remain in sight of its operator, it runs on its original course until he decides to change. Suppose the boat must avoid a reef or the plane regain lost altitude due to striking an air pocket. The operator simply presses his key con- A Pilotless Boat J. Elliott Jenkins, Chi- cago wireless engineer, is shown here with a model of his new radio- controlled steamboat, ex- hibited at a recent radio show. Some day, says Commander Green, every lake and bay and sea may contain many thou- sands of similar marine automatons , trolling the relay for up or down, right or left rudder, and the distant mechanism instantly responds. Springs bring the rudder back to amidships when the opera- tor’s key is released. Use of gyroscopic stabilizers in addition to radio control assures a steadier course. For the long traverse of tank or torpedo, or the great overland flight of a plane, such stabilizers are indispensable. Rough- ness of terrain, adverse currents in the water, and wind squalls in the air all fight for possession of the pilotless machine. It shculd be noted here that scientists at work on radiodynamics are in no sense parties to research of what is popularly called the ‘death ray.” In radiodynamics are utilized only those well-known vibra- tions of the ether that nightly bring us broadcast programs on our home re- ceiving sets. In this connection, Nicolet, the well- known French air- plane engineer, says of stopping motors at a distance by radio: ‘An electric wave such as is given out by an antenna loses rapidly, its force varying as the square of the distance. The impulse created by a (Continued on page 170) its intensity very -

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POPULAR SCIENCE MONTHLY March, 1935 How to Run Your Receiver on 110-Volt Direct Current A Practical Way to Cut Down the High Cost of Batteries By Alexander Senauke, M.E. N A number of our larger cities, the | electric-light service is run by direct current at a pressure of 110 volts. And radio receiving sets require direct current to heat the filaments of the tubes and to supply the plate. Unfortunately, however, the current from the generators in the power houses is not steady enough so that it can be used to operate a radio receiver just as it comes over the wires. This is because the brushes on the gen- erators cause a slight ripple or voltage variation in the current each time they slide from one bar to the next one on the rapidly turning commutator of the gene- rator. If the current from the power house is used directly on the plates and fila- THREE-POLE DOUBLE-THROW SWITCH TO RADIO SET -A TO STORAGE _}| |4. ~ POLARITY BATTERY PLUG Charging Storage Battery Fig. 1. Hook-up for charging radio-storage battery with 110-volt direct current from house-lighting circuit. If you find you are taking more current out of the battery than you are putting in, it is easy to insert an electric toaster in place of the lamp bulb, as indicated in the center illustration above ments of the radio set, these small ripples or waves will be magnified so that the joudspeaker will reproduce a high pitched hum loud enough to drown out the music or speech. ¢ Sow problem is to filter out the ripples from the current supply before it reaches the radio receiver. This can be done in a variety of ways. Figure 2 shows how to use the light current as a substitute for the B batteries, which represent the largest item in the upkeep cost of the radio receiver, particu- larly if it is a large set employing five or more tubes. In the diagram it will be noted that the ground connection is marked “‘Not required.’”’ This is because the ground connection already is made for you through the power lines, since the =B terminal in practically all hook-ups is connected with the +A terminal, and in a great many receivers the filament circuit is connected at some point with the wire that goes to the ground binding post. If you have a receiver in which the an- tenna circuit is completely isolated from the other wiring in the set, you will need to use the ground connection in the usual way, but it is well to insert a half-micro- farad condenser in series with it to prevent short-cir- cuiting the power lines and blowing the fuses microfarads apiece. Condensers Such ag are used in telephone work are Satisfac. tory, and the radio supply dealers carry other styles that are equally good, C is an iron core choke coil that shoul have an inductance between 5 and 20 henries. The primary circuit of an ordi- nary small bell-ringing transformer Made for use with alternating current has about the right inductance. Transformers of this kind can be obtained from any electrical supply dealer for two or three dol- lars. The secondary gp. cuit of a low ratio audio. frequency transformer also has about the right induct. ance. The variable resistance D is placed in the circuit to cut down the plate voltage to the proper value for the GROUND NOT ‘ REQUIRED “s._ == 3-AMP. PLUG FUSES r STORAGE BATTERY RADIO SET POLARITY PLUG The Polarity Test Fig. 3. How to determine which end of the light circuit wire is positive and which is nega- tive. Dip the two bared ends of the wire intoa glass of water into which a pinch of table salt has been stirred. Bubbles will form from one end of the wire. This always is the negative should you be mistaken about the internal connections of the receiver. A and B in the diagram are fixed con- densers with a capacity of from 2 to 4 Cc Battery Substitute Fig. 2. How to use the direct light current as a substitute for radio B batteries. Notice that no ground connection is required in this set detector tube. It should have a maxi- mum-to-minimum range of 100,000 down to 5000 ohms. LL things considered, Fig. 2 repre- sents the best and simplest way to utilize direct current power service to operate the radio receiver. It is true that the A battery has not been eliminated, but it is so easy to recharge a storage bat- tery when direct current is available, that it hardly pays to try to work out a circuit that will eliminate this battery, especially since no one yet has succeeded in figuring out a filter circuit that will eliminate both A and B batteries without also making alterations in the wiring of the receiver itself. In Fig. 1 is shown an arrangement that will result in keeping the A_ battery (Continued on page 172) It is n that « your 1 prope some |

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» 1995 Ich ag tisfac. Carry should nd 20 1 ordi- "Made about ers of tained Supply ee dol- Y cir. audio- er also induct- ance J) cuit to voltage for the SET ‘rent as ce that his set a maxi- )0 down 2 repre- way to rvice to rue that ninated, age bat- ble, that a circuit specially figuring ate both making receiver ent that battery

March, 1925 Novelties of Radio in = D A huge loudspeaker A Powerful Speaker Here is an enormous loud- speaker just designed by C. W. Hewlett, of Schenec- tady, N. Y., for use in public broadcasting. The construc- tion is unique in that no per- manent or electro magnets are used. Instead, the dia- phragm is operated by the induced currents generated in the diaphragm itself by coils of wire placed directly in front of it. Those who have heard this loudspeaker in operation say it reproduces voice and music with won- derful. fidelity and clarity _—> 307-Foot Towers Station WGBS in New York City lays claim to the tallest antenna towers in the eastern section of the country. The tops of the towers are 307 feet above the ground and 107 feet above the roof of the building containing the broadcasting station. Even at this height they are lower than the roofs of many of the skyscrapers surrounding them One Way to Cure Distortion It is much better to build a radio receiver that does not distort, but if in spite of your best efforts to get transformers that will give you the proper quality, you still notice some distortion, a variable _resist- ance connected across the second- ary terminals of the audio - fre- quency trans- former often will work — wonders with the quality bP POPULAR SCIENCE MONTHLY designed for public - broadcasting — Lofty | transmitting towers ' among skyscrapers— / Odd miniature sets

ie

badge adaail LEE VA RSERSS 2988

<—« in the circular 91 Pictures

A Toothbrush Set The craze for miniature radio receivers still continues. One of the latest novelties, built by William L. Wray of New York City, uses the handle of a toothbrush as a base. The picture shows the de- signer with his midget set Cooling Tubes Few broadcast listeners real- ize that the most important problem confronting the de- signer of high power trans- mitting tubes is how to keep them from burning out from heat produced in operation. Water-jacketed tubes offered the obvious solution, but it was not until lately, when radio engineers worked out a system of choke coils in which the rubber tubing containing the water supply was used as wire, that this system was found practical. Water is a fair conductor of high frequency current, but it cannot get through a column of water arranged like a coil of wire, as shown illustration Thimble-Size Crystal Set Another miniature crystal set, recently built by Jack Duffy of Sydney, Australia, is hardly larger than the thimble pictured beside it. This re- ceiver is wound No. 36 wire. The builder says he different stations with it. ees with 30 feet of has been able to hear a number of local Tuning is accom- plished by means of tiny taps on the side of the coil wa sone baal Ce ar Seeeiat ~ TS

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POPULAR SCIENCE MONTHLY March, 1925 How to Build A Two-lube Loudspeaker Set New Type Reflex Gives Ample Volume on a Single Tube By Alfred P. Lane H's: is a radio receiver designed to give plenty of volume on the loudspeaker with the minimum number of tubes. If you are located near several powerful broadcasting sta- tions, this receiver will give volume appeal to radio fans is the elimination from the circuit of any special parts not easily obtained. The tuning inductances AB and CD take the place of the fancy coupling units often recommended for re- flex sets and these inductances are so simple that any one can wind them. And it is an easy matter to change the

Fig. 1. Rear view of the set, showing layout of parts and wiring. Notice particularly how the ends of the wires are fastened on coil A enough for dancing from any of them on just one vacuum tube. And if you area bit too far away for one tube, the design of the receiver is such that you can add another stage of audio amplification with- out changing a single wire already in the set. oor eee MORE, the arrangement of the parts is equally symmetrical, whether one or two tubes are used. The receiver is both selective and easy to tune. If the coils are carefully wound and the two condensers are alike, the two tuning dials will read within a few de- grees of each other from the lowest to the highest of the broadcasting wave lengths, and the readings of these dials may be logged for the different stations heard. With the receiver shown in the illus- trations, I have found it easy to tune in any one of the 11 different. broadcasting stations in the vicinity of New York City on one tube with Joudspeaker strength, using a 100-foot antenna strung up the side of an apartment house. The selectivity can be adjusted to suit local conditions and various lengths of an- tenna by ghanging the number of turns in coil A. Another feature that certainly will number of tubes required to obtain the desired degree of volume, a factor of cOn- siderable importance when the receiver jg to be operated on dry cells, or on a stop. age battery if the latter must be Carried some distance to have it recharged. With two storage-battery tubes, it will overload most loudspeakers on local stations. |, will operate perfectly on storage-batte tubes or either type of dry-cell tube, by the latter will not give as much volume. ‘FE crystal detector helps to keep the quality of the reproduction high, gl. though this is governed to a large extent by the characteristics of the audio. frequency transformers used in the circuit. Here are the parts you will need: A and B—Tube tuning unit C and D—Crystal tuning unit Eand F—Variable condensers, maximum capacity G—Mica fixed condenser, .001 mfd. H—Miica fixed condenser, .00025 mfd. I—Audio-frequency transformer, high ratio J—Audio-frequency transformer, medium ratio K—Rheostat Land 1f—Vacuum-tube sockets N—Crystal detector O—Double-circuit jack P—Open-circuit jack Q—Panel, 7 by 14 inches R—Wooden base board, 614% by 1314 inches S—Binding-post panel, 1 by 6 inches Six binding posts, two dials, two vacuum tubes, brass right-angle brackets, bus wire, etc. -00025 mfd,

Fig. 2. View of the set from above. The layout of parts is symmetrical, whether you use one or two tubes. For a one-tube set, leave out tube socket M and audio transformer J number of turns of wire in any of the coils in order to com- pensate for the peculiarities of the particular instruments you use in building the receiver. The reflex principle is em- ployed because it reduces the

Fig. 3. The well balanced panel layout

March, The not ha’ already they © ever, if down +t D to 5 the br portion HE a} ratio 0! types though numbe! istics 0 differen set. H later. If pre be of t be sur‘ sensitiv are at compar The in this the ty holes d ped in the wor is screv the jac] Figs. 4 have ste hand, y tap the or if y wooden fastened in the 1 screws panel. The course, resistan the tub <, , ‘ | BY ‘ ‘ ' A. :

to use, theostat ticular t tubes in overheat The r commen’ excellent _ After: ineludin: inches Ic a half=p¢

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‘h, 1925 et Te March, 1925 | The variable condensers E and F do not have to be of .00025 capacity. If you already have a couple of .0005 condensers, they can be used. It is desirable, how- r, if larger condensers are used, to cut ie number of turns in coils B and yr 50 turns apiece so as to spread out the broadcasting stations over a greater portion of the dials. HE audio-frequency transformer J has T a ratio of 5 to 1; transformer J hasa ratio of 414 to 1. Almost any standard POPULAR SCIENCE MONTHLY Easy to Tune Mr. Lane tuning the re- markable loudspeaker set that he tells you how to build in the accompanying article. For local stations this set will give ample loudspeaker volume to fill a room on a single tube tain the of transformers can be used, al- r Of con. though it may be necessary to alter the ceiver js number of turns in coil C if the character- @ stor. istics of the transformer used at I are > Carried different from the one used in the model d. With set. How to do this will be explained overload later. ions. It If preferred, the crystal detector N can -battery be of the fixed type, but one can never ube, but be sure that a fixed crystal is really Volume, sensitive unless means at hand to make keep the Gaeasiaive tests. high, al The jacks O and P e extent in this receiver are of + audio- the type that have in the } icles drilled and tap- in the frame, and nese en wooden baseboard is screwed directly to 025 mfa the jacks as shown in Figs. 4 and 5. If you have standard jacks on Tatio hand, you can drill and ata tap the holes yourself; or if you prefer, the wooden base can be fastened to the panel scha in the usual way with ns srews through the , : nel. eid. nthe rheostat, of course, should have a resistance suitable for 93 angle brackets that support ‘them, as shown in Figs. 1, 2, 4, and 5. Small holes also should be drilled so that the ends of the wire can be passed through and back to hold them in place. The way this is done is shown on coil A in Fig. 1. HE ‘number of turns of wire in each coil is as follows: Coil A, 14 turns; coil B, 72 turns; coil C, 15 turns; coil D, 72 turns. Coils A and C the tubes you expect Figs. 4 and 5. Right and left end views, showing the position of parts, and particularly how the wooden baseboard is screwed to the jacks; also how the tuning covered wire for the _ in- ductaneces AB and CD, the first step is to lay out the holes in the panel as shown in Fig. 7. Only the shaft holes for the instruments are inductances are mounted by brass right-angle brackets take up slightly less than a half inch of space on the bakelite tubing, and coils B and D are a shade over 2 inches long. Now arrange all the instruments as shown in Figs. 1, 2, 4, and 5 after you have mounted the panel on the wooden baseboard. Mark where the holding screws belong and fasten all the instru- He bE} ANT. GRD -A At B- touse. Generally speaking, any theostat that is right for_one par- ticular tube will also handle two tubes in parallel without enough excellent results. overheating to make it a serious matter. The rest of the apparatus needs no Comment. Any standard parts will give _ After you have purchased all the parts, Inluding two pieces of bakelite tubing 4 inches long and 3 inches in diameter, and a half-pound spool of No. 22 double silk- Fig. 6. The wiring diagram. The solid lines indicate all the connec- tions for a one-tube set. The dotted lines show the additional wires necessary for two tubes The tuning with library paste. the holes through the paper and after you have drilled them, washed off. This method will prevent scratches on the panel. inductances wound next, after the holes have been drilled in the bakelite tubing for the brass indicated, since there is so much variation in the spacing of the holes for the screw used to mount the instruments, and so many of them are now made single mounting anyway. The easiest way to do this job is to mark off the holes on a piece of paper the exact size of the panel and paste the paper on the panel Then center punch the paper can be should be 1 \," >! 7"— Fig. 7. The panel layout. The holes are for the shafts of the condensers, for the rheostat and for the jacks. If screws are needed to support the condensers, use the templets with them ments in place except the tuning in- ductances AB and CD. leave these off until the wires in back of them have been soldered in place. will save accidental scorching of the coil wire and. will give more space to work. It is best to This (Continued on page 174) ssa oe ase nee siya tne 4 ye F- w4 mn? = i

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Mechanical Oil Service Convenience, accuracy of measure- ment, elimination of waste, and speedy service to customers are ! combined in a newly invented mechanical oil-delivery system re- cently installed in a New York City garage. There two grades of lubricating oil are delivered simul- taneously at two points on each of three floors, or six points in all. The system makes use of gravity and compressed air, the oil being stored in 550-gallon tanks in a fireproof room. The photograph shows two of the taps, each with an individual meter for measurement ms BE Sin FE Spray Cleans Off Grease and Dirt Inaccessible parts of the chassis, such as the running gear and front and rear axles, now are cleaned quickly and easily by a mew compressed-air mechanism that sprays a warm, soapy water solution under pressure to remove grease and dirt POPULAR SCIENCE MONTHLY Auto Shower-Bath From 11 to 14 minutes is all the time it takes to clean a car immaculately by an ingenious mechanical washing system adopted in a new $200,000 auto- mobile laundry in Chi- cago, Ill. A 150-foot con- veyor automatically car- ries each car through a series of washing and cleaning processes con- trolled by crews of men and women workers. In one of these processes the car passes through a shower bath, where sprays wash it from all sides. At the same time, a woman in a gallery above mops the top of the automobile Where Autos Are Groomed while You Wait March, 1925 Better Service for the Motorist Machines Deliver Gas and Oil—A New Auto Laundry | ’ 15 Gallons a Minute Portable tanks for gasoline and oil are eliminated by the latest type of mechanical service equip- ment; which supplies fuel from a storage tank in the garage by compressed air. Gasoline is de- livered to an automobile at the rate of 15 gallons every minute This view of the new automobile laundry in Chicago shows 4 crew of cleaners at work on a line of cars that have come in for a bath. Notice the pressure hoses for cleaning off grease dirt. The cars travel on a rack with a variable speed control damag' you are the ac’ under Hence, else wl must | Also, 8 are int getting UN L rig is qui to adju first at for a.ez throtth whethe mediat When. ment, © motor you—t you mt are sat is as ne Not from t) truck carbur'

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h, 1925 gas, the power you get out of your motor, and the i of —— ; ion you get out of your car de- oo i apa thing more than on a er adjustment of your carburetor. And yet, though this adjustment is one of the simplest that can be made on a motor-car, probably half the automobiles in daily use in America are being operated helow their maximum efficiency because their carburetors are not Ts mileage you get out of your POPULAR SCIENCE MONTHLY By E. B. Staples being in perfect adjustment. I put the truck into service hauling lumber over a 20-mile route. The first round trip con- sumed about 18 gallons of gas. In a week or so, as the truck limbered up, the gaso- line consumption for each trip had dropped to about 15 gallons, but its motor was knocking badly from carbon. Now, although many mechanics would have 95 Make Your Carburetor Save Money Simple Adjustments Add Power to Your Car with Less Fuel If such a marked improvement cah be made with a heavy truck under arduous conditions of service, what can you do to your pleasure car, which you probably operate only smooth roads and under other favorable conditions? A motor shows its maximum power with the carburetor adjusted to supply just enough gasoline to run the car with- out any excess to form carbon. When a motor “spits back” through the carbure- tor, it is a sign of too lean a y adjusted. , 7 aside from wasting causing loss of power, and creating dissatisfaction, an improperly adjusted car- puretor can do permanent damage to a motor. For it means carbon and carbon means knocks, vibration, and eventually ruined bear- ings, a granulated shaft, and shortened life for the motor. Also, small particles of car- bon:pass through the ‘valve lean. openings, and when the valves’ close on them, pits are formed and the valves must be ground. cold. One person only should adjust your carburetor— yourself. The reason is that you are constantly studying conditions. When the motor Useful Pointers to Remember ON’T leave your some one else. Don’t expect perfect results at once. Make your tests on the road under actual driving Simply opening the throttle is not enough. Remember that your carburetor should supply just enough gas to run the car without forming carbon. spits back,” the mixture is too carburetor Do it yourself. “e When it runs irregularly and emits black smoke, the mixture is too rich. Don’t try to make adjustments when the motor is Keep a careful record of your mileage and gasoline consumption. adjustment to mixture. When a motor is choked, runs irregularly, and emits black smoke, it is a sign of too rich a mixture. Somewhere between these two extremes is the point of maximum efficiency which you must seek. N MOST modern car- buretors there are two adjustments, known as “high speed” and “low speed.”’ You will find the location of these by referring to the instruction book that the manufacturer supplied with your car. With your motor warm, turn the low- speed adjustment until the motor idles with absolute steadiness. Retard your the action of your motor under varying conditions of driving. Hence, you know better than any one else wherein it fails, and what changes must be made to make it run better. Also, since you must drive the car, you are interested more than any one else in getting it to run perfectly. tess you chance to hit upon the tight combination immediately, which is quite unlikely, you won’t be able toadjust your carburetor correctly at the first attempt. Neither is the usual test fora carburetor adjustment—opening the throttle suddenly and observing whether the motor accelerates im- mediately — at all conclusive. When you have made an adjust- ment, you must test it where a motor test means something to yoi—that is, on the road—and you must repeat the test until you are satisfied that the adjustment sas nearly perfect as possible. Not long ago I received direct from the factory a new seven-ton truck with a large motor. The carburetor was represented as pronounced the carburetor adjustment good enough, I decided it could be made much better. After a week of careful ad- justing and testing, the car was making its 40-mile trip with a consumption of only 91% gallons of gas. Moreover, it was proving capable of hauling a load one- third larger than formerly. Its motor was free of carbon and running smoothly. Make your own carburetor ad- justments. Here are four standard types of carburetors, one of which probably is on your automobile. Controls for fuel mixture are in- dicated at the left and right spark, and observe whether the motor still idles steadily at the lower speed. If it does not, turn the low-speed adjustment until it does. Then drive up some hill, which you know your car can just about climb in high. If there is the least sign of irregular running, reduce the mixture at the high- speed adjustment and try again. Should the motor “‘spit back”’ in this trial, it will be necessary to enrich the mixture. Repeat these trials, adjusting to compen- sate for ‘‘spitting’ or irregular run- ning, until you are satisfied that the car is operating at its best. Then leave the carburetor at that adjustment, and don’t change it until you are certain a change is necessary. Never attempt to adjust the carburetor while the motor is cold. The adjustment should be made for normal running conditions, which means for a warm motor. Remember, too, that the closer you approach the point of maxi- mum efficiency, the finer will be the adjustments necessary after each test. ISS PUR BOR pa at Ta Be Seacenae ee REE mote cacagebe 5c arte. os ~ hens

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A Bed for Touring () compact auto travel calls for light and

compact equipment. Why not, there- fore, utilize the seat cushions as a bed? They combine spring and mattress and must be carried anyway. By making a framework as illustrated in Fig. 1, one Californian autoist and his wife. converted their car for sleeping and used it satisfac- torily in a trip across the continent to Vermont. When the frame is set up, the cush- ions are placed on it so that they meet on the center cross strip. .. The main weight of the sleeper’s body comes on the springy cushions, while his feet are supported by an easily adjusted

CANVAS SEWED ER I"X2"., Fig. 1. Auto cushions usea for bed on overland tour POPULAR SCIENCE MONTHLY Money-Saving March, 1925 Auto Kinks & P)

canvas hammock. This is made from a 40-in. width of canvas, long enough to reach from the wind- shield bracket. ‘in front to the’ top hangers in the rear. Each end is turned over a 1 by 2 in. wooden strip and sewed. -The can- vas is tied in posi- tion at each corner with a small rope.

Fig. 2. when the oil runs low Motor stops

When packed, Pee the framework is ty Cex. . wrapped in the Ba = < t me & as NP I canvas, making a bit) PAN Se neat roll about 40 | lleseaadil ee Ss in. long and 6 in. ——==j Vex aN \ 4 ae

in diameter. — A. i Sky kn . May Ho.apay. Ss A N SPITE of the {gg a ul tee | care motorists A ‘ give to the oil level | in the crankcase of their car and the ; various oil gages and warning devices in common use, the burning out of bearings is still a relatively frequent mishap. It is quite possible, however, to make a warning device that will stop the motor when the oil level becomes dangerously low. A 4-in.-thick piece of fiber is drilled as in Fig. 2 to allow the oil-float rod to pass through. At a slight distance from the float-rod hole other holes are drilled forthescrews Aand B. The one for Bis countersunk on the under side. Two brass or copper strips are then bent as shown and fastened under the screws. It is a wise precaution to fill the counter- sunk hole for screw B with sealing-wax after the clip has been fastened in place. The fiber block now may be attached to the motor by screw A and another screw at the other end. As the motor is grounded, screw A and its clip are grounded. A metal washer of LEATHER FOOT-REST ON ACCELERATOR PEDAL Fig. 4. Cover for pedal

MN SO} Fig. 7. as ‘

PA SONAHY VALVE GUIDE

tacts. door pocket.

Fig. 5. Lumber-carry- ing extension for truck. Upper with view shows it rack extended; lower, folded within body Starting valve guide PIPE WRENCH brass or copper is fastened to the float rod and so adjusted that when the oil level is low it will rest upon the two spring con- The wiring consists of a single wire running from B either to the binding post where the current enters the inter- rupter, or to the coil.—R. H. KASPER. AN AUTOIST fashioned a handy clip ‘to hold his tire gage just inside the A piece of light but stiff sheet brass, 1 by 3 in., with corners rounded and edges filed smooth, was bent

and Six Other Aids into a shape (Fig. 3) to fit on the edge lining. A flat-head brass bolt, 14 by % nae was screwed into place, the projection he = the nut noted, and the bolt removed and filed 4 down to exactly the right size. 4 gage prevents it from dropping.—R. C. T. n_ beyond The rim on the RETIRED army officer in Wash. ington has fitted the accelerator of his auto with a cover flap’ of stiff sole leather about 4 by 7 in. (Fig. 4)?-The ad. vantage of this is that it distributes the pressure and also reduces the likelihood of his foot’s, slipping off the ‘pedal: The leather does not interfére - with’ the Te moval of the floorboard, as it is pliable enough to be bent back and. -out of the way of obstructions.—G. A. Li. TT? ADAPT 4 Ford truck with a short body for carrying lum- ber, my father build a frame ex. tension, as shown in Fig. 5. It is made of 1% by 3% in. lumber, fas. tened with in, bolts and pivoted to the sides of the FLAPOF DOOR POCKET cal] SECTION SHOW|NG TIRE-GAGE CLIP IN DOOR POCKET

HOLE FOR 6'X/4" BOLT truck body. — Fig. 3. Brass holder JANET LINEBAUGH. keeps tire gage handy \ , 7 HEN a large DIAGONAL ° — TANG OF screwhead HOLES Ait FILE breaks, it is often - possible to remove the screw by drill- ing a small hole diagonally into the slot. and inserting the tang of a file or other tool to’ act as a lever, as in Fig. 6. When screws are to be i- serted in a deep recess or. in any very awkward or inaccessible place, it is possible to fasten the screw to the tip of the screw- driver with a drop of solder. In some cases, as in repairing the oil circulating system of certain truck cylinder blocks, this method is used in conjunction with special screwdrivers of long reach made, as shown in Fig. 6, from cold rolled steel. SPECIAL SCREWDRIVER Fig. 6. Turning screws i Rese: removal of valve guides from the cylinder castings of the automobile often may be accomplished by giving the bushing a twist with a pipe wrench, 3 shown in Fig. 7. Once started, the bushing is readily punched out of position. ARBURETORS with cork floats som times fail to work because the float becomes soaked with gasoline. The float should be removed and carefully baked dry in the oven. Three or four very thin coats of shellac then should be applied. Do not get shellac on too thick.—H.L. W.

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he door n., first beyond nd filed On the | Wash. rator of tiff sole The ad. utes the ihood of l. The ‘the re. + pliable t of the EBA UGH. | a large ewhead is often remove by drill- all hole ‘into the inserting f a file or | to’ act r, as in When to be in- a deep in any ward or le place, sible to e screw- In some rculating r blocks, ion with ‘h made, led steel. from the tomobile iving the rench, as » bushing n. ats some the float The float ly baked very thin applied. H.L.W. *)* 4 POPULAR SCIENCE MONTHLY Arthur Wakeling, Editor By Robert V. Jaros LL-AROUND flying performance is what affords the greatest satisfaction in a model air- Kh plane. The exact model of \Y a large machine may have \ an excellent appearance, but be a very poor flier. Consequently the twin pusher model illustrated is my favorite because it em- bodies in its simple and sturdy construction the qualities of a consistently dependable flier. The lack of tools is not a handicap in model airplane building. Very good con- _ struction can be obtained by using only a_ pocket knife, a small block plane, a candle, and a pair of pliers. The block plane need be no larger than the 1-in. size, which can be bought very cheaply. The materials are simple and inexpen- sive. Bamboo, white pine wood, glue, silk thread, steel piano wire No. 13, tissue paper, ‘banana oil,’”’ 14-in. washers, and rubber are all that are necessary. The best bamboo is that which has a glossy outside surface and joints that are far apart. Dress spangles, which may be bought in the fancy goods department of a dry- goods store, serve well as _ washers. Banana oil may be bought by the ounce at almost any drug-store. The A-shaped frame is composed of two main beams of pine, 9/32 by 3/32 by 36 in., braced by a series of bamboo cross pieces. The beams should be planed Top view showing main beams, braces, and location of wing, elevator, and propellers down and sandpapered smoothly to the correct size, and then small slits, through which the cross braces‘ will extend, should be made in them. It is easiest to make these slits by laying the beams Easy to Build Fast Model Airplane World Champion Tells How to Construct Miniature Aircraft flatly on a board and forcing the point of a small knife blade carefully into the wood (No. 1, Fig. 2, page 128). , The ends where the beams will meet should be cut on a {> bias to in- WING TIP MAIN BEAMS BAMBOO ELEVATOR —— N- __ELEVATOR __ “a These aoe nN : ) 3a” Ga 2 | | / \ \ I ’ } \ rt / \ / rs x. Eon oo fe % n= sl i A — WING DIHEDRAL Fig. 1. Top, side, and rear views of the model, and diagram illustrating wing dihedral Where to Find This Month’s Mechanical Features The Home Workshop Pages 97 to 140 The Shipshape Home Page 142 Better Shop Methods Department Pages 102 and 144 to 158 Jaros Holds World’s Record i for Model Airplanes N TELLING fs the readers ed of POPULAR ‘ SCIENCE MONTH. , } LY how to build (\F a small plane, — i Robert V. Jaros is drawing upon the fund of experience that enabled him to set the world’s record for model flying. Repre- senting the Illinois Model Aero Club in competition at the last Sreat international air meet at Dayton, Ohio, he won the Mulvi- hill trophy for that organization. His model remained in the air 10 minutes, 14.2 seconds, and trav- eled about two miles. Jaros, who is 19 years of age, is a student at the University of Michigan. sure a close fit. After this has been done, force a wire hook, made with the pliers, over the ends, and glue and bind with silk thread, as in No. 2, Fig. 2. On all constructions glue should be ap- plied before the thread is wrapped around. The binding should be tight and the thread tied. The cross braces are cut out and shaved down with a knife from a larger piece of bamboo. They should be cut so that one In flight, the elastic-driven propellers push this little monoplane model from the rear of the wider surfaces is of the glossy out- side part because the greatest strength of bamboo lies in this part. The cross braces at the widest part of the frame, that is, the rear of the model, (Continued on page 128)

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98 POPULAR SCIENCE MONTHLY A Decorative March, 1925 Desk for Your Home How You Can Construct an Unusually Beautiful Piece of Furniture pieces of furniture described in the Home Workshop, you are perhaps ready to try your hand at something a little out of the ordinary. Such a piece is the beautiful writing- desk detailed in the accompanying drawings. The design is based upon an early American desk of Sheraton influence in the Metropolitan Museum of Art, New York. Some modifica- tions in size and detail have been made by George F. Kaercher, the furniture-factory superintendent who prepared the working drawings, in order to adapt the desk better to modern purposes. The style nevertheless re- mains essentially that of ie YOU have made some of the simpler U_ Bead molding ends on edges, \% by 1 1/16 by 171 2 a lide board, % b . hy Desk slide board, % by 8% by 24 11/16 ; iy ‘Wiiling, top of bane Gallows. cae 1 by gauired - - fb ( 41 olding, top of base (mitered), 1% by 1 required ‘. ( 7a by thy aes Legs of base (square or turned), 2% by 2 uae: , b . abr ra by 27%, End rails (13 in. between shoulders of tenon i long if doweled), % by 6 by 14%, 2 required staal. Back rail (22 in. between shoulders of tenons 22 in. long, if doweled), % by 6 by 2314, whitewood, 1 re. quired BB Drawer front, % by 6 by 22, 1 required CC | Drawer ends or sides, }4 by 5 by 15%, whitewoog 2 required : - DD gine back, 4 by 414 by 21%, whitewood, 1 te. quire EE _ Drawer bottom, 4 by 154 by 21%, 3-ply, 1 required ; (Continued on page 124) the magnificent model ne a shown in the central pho- tograph. If made of mahogany, the decorative bandings should be walnut veneer aN a ; ay uit, it and conversely, if walnut = ql Me, is used for the main parts, TON | the bandings should be of =~} Ns mh en mahogany. The box part, including the front, is S| S WWM = 4 = made of %-in. thick 5-ply | 4 veneer, if obtainable, and | ¥ Q a special effort should be made to select for the front a piece having a face veneer of rich and striking figure. Any one who has had sufficient experience to build this piece, wil! find that the working drawings show practically all that need to be known about the construction, when 6" Note. Slide Board V ts pulled taken in conjunction with forward to close Gap when the following bill of ma- terials. The stock is either mahogany or walnut, ex- cept where otherwise noted. A Top and bottom of desk, Drop Sis in writing position % by 10 by 26%, 5-ply (or solid), 2 required Ends of desk, % by 10 by 19% 5-ply (or solid), 2 required LL ye VENEER Back of desk, % by 264% by 19%, 3- or 5-ply, 1 required D_ Top and bottom, interior, 4 by 8 by 244, whitewood, 2 required E Ends, interior, 4% by 8 by 16%, whitewood, 2 required F Shelves, interior, 44 by 8 by 244%, 2 required G Shelves, interior, 4% by 8 by 8, 2 required H Partitions, interior, 4 by 8 by 8%, 2 required I Partitions, interior, 144 by 8 by 44, bandsawed, 4 required J Drawer fronts, interior, 14 by 3 \% by 24, 2 required ANSRRRAARNEE CY Drawer backs, interior, 3/16 by 3% by 23%, 2 required L_ Drawer sides or ends, inter- ior, 4% by 3% by 7 %, 4 required M Drawer bottoms, interior, \% by 7 \% by 23 %, 2 required N_ Drawer. fronts, interior, \% by 4 by 8, 2 required O Drawer backs, interior, 3/16 by 3% by 7 &%, 2 required P Drawer ends, interior, \4 by 4 by 7 %, 4 required Drawer bottoms, interior, PHOTO COURTESY METROPOLITAN MUSEUM OF ART Q \% by 7% by 7 %, 2 required R_ Center brackets, interior, Y% by 3 by 4, 2 required S Desk front or drop, % by 17% by 24%, 5-ply (or solid stock with mitered end battens), 1 required T Bead molding on edges, ¥% by 1 1/16 by 24%, 2 required ee = é : EARLY AMERICAN ING- DESK In Mahogany and Walnut. The design is based on an Early American Desk of Sheraton Influence, made of Mahogany and Satinwood. in the Metropolitan Museum of Art, New York _ get © © or ere we ee er ee oe ee a we oe ore

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March, 1925 POPULAR SCIENCE MONTHLY 99 e| How to Finish Furniture . —New and Old ATH, qui 144 1054, 2 y 27%, t 13 in, Ons, or d, 1 re. wood, d, 1 re. 2, 3-ply, 2 UA: : JOHNSON’S WOOD DYE (Penetrating) ) ! If you have a hobby for making chests, | Johnson’s Wood Dye is for the artistic | cabinets, furniture, porch swings, radio coloring of all wood. It is very easy to boxes, etc., you will find our book on apply—dries in four hours and will not a Wood Finishing invaluable. For, nat- rub off or smudge—penetrates deeply, urally, you want to give your handi- bringing out the beauty of the grain. iW work a beautiful finish. Madein 17 beautiful shades, among the i : ’ : most popular of which are: B J Our Book gives complete instructions —" fe for finishing new and refinishing old 123—Dark Oak 131— Walnut 129—Dark Mahogany 126—Light Oak wood—soft or hard. .It tells how tostain 127—-Brown Mahogany 124—Gelden Oak wood artistically—how to remove old paint and varnish—how to secure a Order Johnson’s Wood Dye from your beautiful enamei finish. dealer by name and number. Ask for a FREE copy of the Johnson Book at stores displaying the sign shown at right. These stores carry Johnson's ee ES - Artistic Wood Finishes and will be glad to show you wood panels—and answer questions on how to properly finish SERVICE PROPER wood. If no store in your locality can supply the Johnson Book—mail this coupon for a copy Free and Postpaid. DEPARTMENT ENT | PRAT] «YOUR DEALER'S NAMB. enn \ Wwerere hi neleaas (ae NN Sas Roe ee Tae nee ee eer baieiciewiacaisdelnascenctecteen Your Address................ ind FURNITURE City and State............ Mailto: S.C. JOHNSON & SON, Dept. PS3, RACINE, WIS. *“‘The Wood Finishing Authorities’’ (Canadian Factory: Brantford) PERE PERE eT PT PPP RP CPP ET |) op hee RE CRETE TP VRE TE Git Tee Tas © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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100 POPULAR SCIENCE MONTHLY

March, 1995 Linen Cabinet Made from Boxes By Emanuel E. Ericson Noted Manual Training Authority HE need for an inexpensive linen cabinet resulted in the unusually simple and satisfactory construc- tion illustrated. Shelves with a 3-in. edge piece on the front are used instead of drawers. This not only cuts down the work of building the cabinet, but saves the housewife from having to open and shut heavy drawers. All the lumber, except the pieces for doors, which are 14-in. thick white pine, and the back, which is wallboard, can be obtained from packing boxes. Much’ useful lumber can be obtained from boxes if care is taken not to split the boards. If the boards are longer than will be required, the best way to get them loose is to saw them off close to the ends of the box, leaving the nails undisturbed. If a nail-puller is available, it can be used effectively in saving the whole boards without splitting them; a hammer will serve, however, if careful work is done. The top is glued together from two boards with a matched joint found on a box, the clamping being done with wedges as shown. The two facings to which the hinges are attached are nailed and glued. The cross pieces on the inside of the doors are fastened with flat-head screws,

How the top is glued and clamped to- gether with wooden blocks and wedges

The. fin- ished cab- inet (at left); us- ing screw in block as mark- ing gage, and chis- eling a rabbet (below) the holes for which are enlarged slight} to allow for contraction of the lumbe, without cracking. No glue is used. Yo little change in these boards wil] u place, however, if paint is applied on both sides, provided the lumber is reasonably dry. The recess or rabbet for the back is cut out with-a chisel. Before the case is nailed together, all the pieces must be planed arid ganq.

1146%3-3 DOORS

rf

CASE |S 12'5"DEEP WALL- ues 2'-2'2" WIDE BOARD sf \ 4'-'" HIGH Zz ZZZZZN

The general dimensions and construction of the case and sectional details of the shelving eo erm mom

papered thoroughly. The top is attached with eightpenny finishing nails and the shelves are nailed in through the sides of the case. The hardware consists of two pairs ot small steel butt hinges, one small elbow cupboard catch for the inside of the left door, a spring ball and socket catch of the type used on phonograph doors, and a glass knob, all bought at a 10-cent stor for 30 cents. One can each of white paint and enamel, costing 20 cents, with a spoonful of putty, suffices for the finishing. After the priming coat, all nail holes and crevices are puttied, some sandpapering done, and another coat of paint and one coat of enamel given,

Neat and Durable Hotbed Costs $24 to Construct 1* YOU are planning to build a small hotbed—and a hotbed is an invaluable adjunct to any garden—a good model to copy is the one illustrated. It cost $24 for

The com- pleted hotbed and one corner of 5-2. s:h showing water channels materials, but will last at least 10 years. It is about 8 ft. long and 4 ft. wide, with hinged sash. The pit, which is walled up with concrete, extends 2 ft. or a trifle more into the ground. The main frame is bolted to the con- crete foundation. The ridge is a 2 by 4 in. piece, set flat and planed to fit the sloping edges of the sash. Note the grooves in each sash; they permit water to drain from the glass—DALE R. VAN HORN, Walton, Neb. Radio Tool for Many Uses Made from Old File Ye Ye-Ho HOLES

Ye Kita WNP Mids) WY \ i X Mia s Ll Bh Mees af ‘i ND NN BYNYYXYOXY AXA KKK SELAH OY OXY SIREN

Her| | O= radio fan who takes pride in being able to make emergency repairs to almost any kind of a receiving set, car- ries with him a tool made as illustrated from an old flat file. The file was heated bright red and allowed to cool. It was then sawed, filed, and drilled and bent at one end as in- dicated above, and retempered.—G. L.

Jack Saves Labor in Raising Posts from Ground FINDING it necessary to remove tm. 4 by 4 in. clothesline poles, I raised them from the ground by using an aute mobile jack, as shown. Blocks were

nailed on to take the pressure of the jack and of the brace in the rear that prevented the post from tipping backward. It took about five minutes to lift each post.

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POPULAR SCIENCE MONTHLY Het. SEATED. RUE whens, MIDWEST RADIO CORPORATION iS) Pioneer Builders of Sets Caneel eae 408-W East Eighth Street iculars regarding Send free literature, your special offer, — hg —" g Miraco Sets. 0 Jobber. © Dealer. O Agent. eeaeeeeeeseeseeeeee Name... Peta eraweevernucess eeece Address... ech mweane weed UTE OF STANDARDS. See Page 33.

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POPULAR SCIENCE MONTHLY

March, 1925

Winning a “Shop Race against Tim Old Bill Bores a 7-Foot Pulley on a 20-Inch Drill Press

FEW minutes before time for Old Bill and his boys to begin work, a mud-covered truck rattled and coughed up to the door of the shop. Several sleepy-look- ing. men were on it, and one or two who did not seem so tired. The truck was hot, and had all the signs of having made a long trip in a hurry. The human cargo unloaded and brought to light a big, rusty pulley that looked as though it had been rescued from the scrap heap. The shop men coming to work stopped and looked. One asked what was to be done. The man in charge replied that he wanted the hole bored out to fit a 4 7/16-in. shaft. ““We broke a pulley this size on the main lineshaft last night,’’ he explained, ‘‘and happened to find this one out in the yard, where it had been discarded a long time ago. It is just the thing, but the bore is too small. It is wider than the old pulley, but that will not matter.” The shop man gave one of those peculiar whistles that those who work about machinery use to indi- cate amazement. “There isn’t a machine in the shop that we can put this in at once,” hesaid. ‘‘I suppose you want to get this right away?” “You bet we do!” the mill man re- turned. ‘‘The boys and I,” he waved toward his companions, “have spent most of the night getting this pulley out of the yard and bringing it here. Until we get this, the whole plant will have to stay shut down, and most of the men will be laid off. Weare behind on a contract, and I hate to think of what will happen if we lose much time!”’

James Ellis © igoue Bill came along about this time and surveyed the truck, the men, and the wheel. He recognized the speaker as Jack Hayes, engineer at the Johnson Mill Company. “Well, Jack, old scout, what sort of trouble are you bringing me this time?” was Old Bill’s greeting. “‘Bad trouble!” the mill man replied, ‘‘and you have got to help me out!” “All right; that’s what we are here for,” Old Bill said with a smile. ‘‘What do you want done?” “This pulley that we have dug out of By James Ellis Machine-Shop Superintendent the scrap pile is just the size of one that broke on the main lineshaft last night, except that the hole is too small. Your job is to bore it out, and do it in a hurry!” ‘Looks to be about seven feet,’ Old Bill said, half to himself. ‘Too big for the “Imagine what a oe place this would be uf Aa ; oo if we got too ex- < 1 fe Fy cited about these i \ rush repair jobs,” a said Old Bill to the mill -owner’s son

boring mill—Well, maybe we could raise the big lathe.” “That long shaft is in the big lathe,” Bob Laton, one of the machinists, re- minded him. “That’s so. Then I guess we’ll have to do something else with it.” The work whistle was blowing. The men started in to their machines. Old Bill spoke to one of them, who called to several others to help him roll the pul- ley into the shop. Old Bill went on with his accustomed routine, going from one machine to the other to see how his men were progressing. Hayes became impatient and explained again the necessity of getting the job done at once. “‘T have brought a lot of men with me to help you if you can use them,” the mill man continued. ‘‘I have the big boss’s son along also. The Old Man thought that he might like the trip, or something. I suppose he expected him to speed you up; at least, that is what he said!” “Well, we'll get you out all right,” Old Bill promised. ‘You fellows had ‘bette run off and get some breakfast. iI wij attend to the job.” They did as Old Bij suggested. When they came batk, t were surprised to find the pulley still standing where it was. Young Johnson came up to Old Bill, “Don’t say it!” Old Bill cautioned, “] know that you are going to tell me that this is the most important thing in the shop, and that I ought to think about nothing else!” The young man looked sheepish, tor that was exactly what was on the tip of his tongue. “It may seem that I have not given your job a thought; but I have,” Old Bill continued. “I think you heard the boys say that there was not a machine in the shop that would swing this wheel.” Johnson nodded assent. “Well, I have found a way to do it, and before long you will see something happen.” Bob Laton was coming over to Old Bill with a few tools in his hand, “‘T have got the new man started on the job that I was doing,” he said, ‘“‘and as soon as I put away these tools, I will get the pulley over to the drill press.” “We shall have to do it on the 20-inch drill,’’ Old Bill said. “Tfor- got that I had a lot of drilling to be done on the radial when I told you to put the wheel there.” Laton looked puzzled. **On the 20-inch drill?” he ques- tioned. He looked over to where the wheel was, as if to make sure that it was as large as he thought. Then he burst out, “Oh, I see! I'll get right on it!” And he did. Young Johnson followed him to the job. Laton may have seeh, but Johnson did not see at all. 5 Hew in the world are you going to get that big pulley into this little machine?” lie asked. Laton replied with a laugh. “Easy,” he said. ‘This pulley of yours is split, so we will take it apart and put it together around the machine!” It was not long before the pulley had been put together again around the col- umn of the drill press. Its rim was blocked up from the floor. Laton went to the toolroom, bringing back a boring bar, which he fitted into the spindle of the (Continued on page 150) ON’T fail to turn to pages 144-158, where you will find the continua- tion of the Better Shop Methods De partment.

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+ 1925 t on the . “Tor ing to be told you he ques- to where sure that Then he right on followed ve seen, going to this little r of yours nd put it ulley had 1 the col- rim was iton went a boring dle of the s 144-158, ‘ontinua- hods De The Choice of Two Generations Back of your Starrett Tools is the satisfaction of two generations of crack machinists. Find the best mechanic in any shop and invari- ably you will find a Starrett booster. His work calls for the Closest fits, the closest limits, the closest measurements. The Pre- Cision Tools it takes to do the job, he’s got. Naturally, his choice is Starrett. Accuracy, of course, but THE L. S. STARRETT CO. World’s Greatest Toolmakers 7442 Manufacturers of Hacksaws Unexcelled ATHOL, MASS, In this group of Starrett Tools are the Improved Universal Bevel Protractor No. 359 (with Fine Adjustment), Toolmaker’s Dividers No. 277, Inside icrometers No, 124, Automatic Adjustable Stroke Center Punch No. 18, T-Handle Tap Wrench No. 93; and Toolmaker’s Universal Surface Gage’ No. 56. All completely described in the Starrett Catalog of 2200 Fine Precision Tools. Write for No. 23“ Ww". POPULAR SCIENCE MONTHLY more than that. Design that means easy, rapid work. Workmanship that keeps a Starrett on the job years beyond the serviceable life of other tools. Confidence that comes through working with Tools he’s always found reliable. Toolmakers, Foremen, Inspectors —they’re not using Starrett Tools for the fun of it. The pay envelope tells the story. ® This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. Why lo the Toolmakers work with Starrett Tools 103 acer neem ve naan emameete nn sae Set aaet Se ase

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Drilling out cylinder head bolt close to cowl—an awkward job made easy by ‘‘Yankee’’ Double Ratchet. Tight against the cowl yet he drills easily He doesn’t need space to revolve crank of “Yankee” Ratchet Breast Drill. When set on DOUBLE Ratchet any slight movement of crank back and forth causes drill to cut continuously. By doing the otherwise impossible jobs, a “Yankee” Ratchet Breast Drill saves ‘* time and expense of taking down construction. “YANKEE” Ratchet Breast Drill No. 1555 Five ratchet adjust- ments changed by touch on Ratchet shifter. Two speeds, changed with- out removing drill from work. 3-jaw chuck holds round shank drills up to %in. No.555. 2-jaw chuck holds both rounds and squares up to 4 in. Dealers Reorrw tere. Sell **“YANKEE OLS “Yankee” on the ae you buy means the utmost in quality, efficiency and durability. Write for FREE Tool Book YANKEE’ NOISS5 Five Rachet Adjustments 1. Plain Drill 2 Left-hand Ratchet 3. Right-hand Rachet 4. DOUBLE Rachet 5. Gears Locked NortH Bros. Mrc. Co., Philadelphia, U.S. A. “YANKEE” TOOLS Make BettOv Mechanicy POPULAR SCIENCE MONTHLY O YOU have occasion to call your neighbor on the phone quite often? Possibly your most intimate friend lives only a few hundred feet away and you use up a lot of phone calls talking to him. If this is the case, you can rig up a simple telephone line between your houses that will permit you to talk with him as much as you want without expense for phone calls and, furthermore, no one can listen in on your conversation. Look over the accompanying wiring diagram. Assuming that you are both radio enthusiasts and are possessed of a pair of head phones apiece, the only addi- tional apparatus you need will be two SINGLE WIRE TO NEIGHBOR'S HOUSE CHEAP WOOD BASE 3-CONTACT SWITCH a BINDING POSTS FOR PHONES _4'4-voiT RADIO A ra C BATTERIES ~ ay TO NEAREST WATER PIPE Wiring diagram, showing how the batteries, bells, switches, and phones are hooked up ordinary switches, each with three con- tact points, a couple of house bells or buzzers, two of the C batteries sold for radio use, and a length of single wire sufficient to reach from your house to his. If no head phones are available, buy one cheap pair and use one unit at each end. The arrangement of the wiring is such that you can call your friend or he can call you at any time, yet there will be no current flowing in the wire when the line is not in use. Each switch should be left with its How to Rig a Simple ee Line to Your Neighbor’s House lever on contact C. If either switch js moved to contact A, the bell at the othe end of the line will ring. After the person at one end of the line has made a call in this way, he moves his switch to point B and talks into one of the head phong while he listens with the other. The party receiving the call also moves his switch to point B and proceeds to talk in the same fashion. When one unit is used at each end of the line, both the talking and listening are done with it. Be sure to connect the batteries as shown, for if you get one of them re versed, they will oppose each other and no current will flow through the phones when the switches are on points B and B, In the Workshop Schedule OMING Home Workshop features are: ‘‘Re-Upholstering Chairs,” ‘A Wallboard Screen,’’ ‘‘A Toy Pas senger Air Coach,’’ ‘‘Methods of Adding Speed to a Speedster,’’ ‘‘A Child's ‘Motorcycle’ with Sidecar,’’ ‘What Makes My Ford Creep,”’ and ‘‘Repairing a Porch Column.”’ Prizes Offered for S THIS issue of Poputar ScrENCE MonTHLy goes on the newsstands about February 10, you may still have time to enter the contest for handi- craft photos announced Jast month. A First Prize of $25 A Second Prize of $15 A Third Prize of $10 are offered for the best photographs of the more uncommon and _ ingenious handiwork of amateur craftsmen. Perhaps you have built a strikingly original piece of furniture, a model, a toy, sporting equipment, scientific ap- paratus, or some sort of household utility. If so, photograph the piece, write a description of not more than 2 words telling what it is and how you came to make it, and send it to PopuLAaR !! Still Time to Compete for the $50 in Handicraft Photos!! Science Montnury, 250 Fourth Ave. New York. Mark the envelope ‘‘Handi- craft Photo Contest.” In many instances it many be advisa- ble to submit two photos, one an attrac- tive picture showing the object in use | and the other giving a close-up of its construction. Photographs that do not win prizes, yet are available for publication, will be purchased at regular rates. All photographs must be received on or before February 24. The Board of Editors of Popucar ScreENcE MontHLy will act as judges and their decision final. Unavailable photographs be sent back only when accompanied by a_ self-addressed label bearing retum postage. The winners will be announ as soon as possible after the judges com- © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS, plete their task. See page 33.

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rch, 1995 switch js the other he person » a call in © point B d phones er. The noves his to talk in ch end of tening are tteries as them re other and he phones 3 B andB, edule POPULAR SCIENCE MONTHLY rd r } Ready with your Kodak There’s a real thrill to the picture that breaks on the scene without warning. Out | comes your Kodak; quickly and easily you bring it into play and—the picture that found you prepared, soon finds a place in your album. Autographic Kodaks $6.50 up Eastman Kodak Company, Rochester, N.Y, 7%e Kodak City rIS} This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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POPULAR SCIENCE MONTHLY March, 1925 What Makes the Wheels Go? From the boyhood experiment with the family clock to the full- grown problems of machine de- velopment—the question holds. Motors supply mechanical energy, while Veeder Counters supply human energy to make machines beat their own best records for output. On the dial of a counter your ma- chine indicates “what makes it go.” What mechanical features or operating methods make it go BETTER, as shown on -the COUNTER The Set-Back Rotary Ratchet Counter below is for machines such as presses and metal-stamping machines, where a reciprocating movement indicates an operation. Registers one for each throw of the lever and sets back to zero from any figure by turning knob once round. Supplied with from four to ten figure-wheels, as _re- quired. Price with four figures, as illus- trated, $11.50—subject to discount. (Cut less than 1% size.) Set-back Revolution Counter of similar model, $10.00 (list). Thissmall Rotary Ratchet Counter (No. 6) counts reciprocating movements of the lever, as required for recording the output of innumerable small machines. When the lever is moved throughan angle of 40 to 60 degrees, the counter regis- ters one. The further the lever is moved, the higher the number registered. A complete revolution of the lever registers ten. This counter can be adapted to no end of counting purposes, by regu- lating the throw of the lever. Price, $2.00. (Cut nearly full size.) Small Revolution Counter, also $2.00. Whatever you need in a count- ing device is shown in the 80-page Veeder booklet. Your request brings it promptly. The Veeder Mfg. Co. 44 Sargeant St., Hartford, Conn. © This seal on a radio or tool | ARM lighting plants cost money, even the least expensive, but for a few dollars any rural dweller can rig up a low-voltage plant that will give light at little expense. The one illus- trated is composed of an automobile 6-8- | volt generator and two storage batteries. The generator was charged to profit and | loss on a wrecked car, as was one battery. Another battery was later added to give | longer service on a single charging. The generator was thoroughly over- hauled and cleaned. mH AHHH \\" ‘| AAT | li Hl i} | | iy Hil rae Vest-Pocket Lighting By Lawrence B. Robbins SS Plant generator, G, is eon- nected with the lever of the rheostat, R. The other terminal of G goes to switch point 4. Point 3 then goes directly to battery B. The voltmeter y is shunted across the battery terminals, Switch point 1 also is connected with the wire from 3. The opposite B terminal connects by switch X to both main wire terminals, Nos. 1' and 2'. The other R terminal (from end of re- sistance wire) goes directly to the am- meter, A, and then to 2'. From a point between A and R a wire should be shunted across to 4 and 2 and a second pair of wires connected with a 6-volt lamp, L, which is shunted across the main side of A and the wire from R to 4, | Arrange 1, 2, 3, ie and 4 so the lis switch S ean be swung across 1 Then it was TTP | fitted with a My it4| 144-in. pulley hia | pn ual int and mounted SSA, ee 1); us on a plank over | a small pumping engine | in the cellar. It was belted directly to the 4-in. engine pulley. Ata ' normal speed of 400 r.p.m. the engine | serewing both to the wall. drove the generator between 1000 and 1200 revolutions—sufficient to generate eight volts. The wiring diagram shows how this plant was hooked up, using a homemade rheostat and a circuit-changing switch. The rheostat was made by tacking a sheet of 14-in. asbestos to a board and Ten brass tacks were nailed along the top in a line and 10 more in an arc below them. Then No. 20 German-silver wire was stretched back and forth from one tack to the next, as indicated. A brass switch lever was pivoted in | the center of the rheostat at the bottom so that it would | touch the~ tacks throughout the are. [ The circuit- }|' changing switch ——_ was cut from stiff > | sheet brass about5 = : Pd |in. long after the —5 | pattern shown. MAINS __,- The explanation 3 * | of the wiring dia- WIRING DIAGRAM a sa follows: Rheostat, control One terminal of the switch, and hook-up An auto generator is the heart of this small lighting plant BRASS TACKS ASBESTOS SHY Ii ‘ \i\:\ | WAI tor. The house wir- GERMAN] 11/1] | by | i t be done WaRRee aa ing mus ver ph (Lt I Ll with wire not small- LEVER// er than No. 12. [RHEOSTAT__—ss—s“s«sSEIn. this particular and 2 or 3 and CTT 4. Also con- nect the positive terminal positive terminal of B. To charge, swing S down across 3 and 4, start engine, and then swing switch X over to 2'. This allows charging current to go through R, where the voltage is regulated in case the speed of engine be- comes excessive, as indicated by the read- ing of the voltmeter. From R it goes through A to B and back again through 3 and 4 to G. Figure L lights to aid the operator in watching operations and also acts as a pilot light. When the charging is done, shut off the engine, swing X to 1, and S up to 1 and 2. This leads the bat- tery current directly to main wires and cuts out the genera- of G with the TIL TW system the owner uses regulation auto- headlight sockets (Continued on page 124) PIVOT ~ HANDLE advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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» 1925 con- ar of of G goes ar V nals, . the inal oint l be nd 2 wires -volt nted of A to 4. 2; 3; the un be Oss 1 h the 3 and tch X urrent age is ne be- read- t goes ugh 3 id the d also off the and 2. e bat- irectly s and enera- se wirl- done small- 2B ticular owner n auto- yckets ge 124) POPULAR SCIENCE MONTHLY Mics sce ae TE ai, Pie 5 % {OnenonchReacongyy Because of skilled workmanship every Brown & Sharpe Tool is sure to satisfy its owner. Made with modern equip- ment in the largest factory of its kind in America by experienced workmen, it is destined for a long life of precision and service. Skilled workmanship is only one more feature of the excellence of Brown & Sharpe Tools—an excellence which makes them good tools to own, * j | | You'll notice the kits of mechanics who know good tools are Brown & Sharpe equipped. Send for Small Tool Catalog No. 29. It lists over 2000 of the world’s finest tools. Brown & Sharpe Mfg. Co. Providence, R.I., U.S. A. @® This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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Perfect ending. Tonal Beauty Lies Deeper than the Varnish EPER even than the cir- cuit diagram — chiefly, indeed, in the audio trans- former. All-American engineers, builders for years of the largest selling transformers in the world, have achieved another triumph, in a new type of transformer which has proven a revelation to music lovers. Lyric amplification, with an ordinary tuner and loud speaker, has received the plaudits of musical author- ities hitherto skeptical of all radio reproduction. There is romance in the story A request will bringit to you complete— from the originallaboratory studies to the auditions with world-famous music critics. Rauland Manufacturing Com- pany, 2668 Coyne St., Chicago. of Rauland-Lyric. Price $9.00 Ask Your Dealer pre AMERIc TRANSFORMER The Choice of the Noted Music Critics Rauland- amplification makes of radio a joy un- Who shall say that such a benefit is not worth the slight addition- al cost? POPULAR SCIENCE MONTHLY Spirals the other operations were the same. In the upper end of two of the legs,a [1 ak ag single mortise is cut =| WT 7» ois to accommodate the i ee: oe corresponding tenon of the side rail. In ee i BE EN SSE By William J. Edmonds, Jr. TT stand illustrated below incor- porates spiral turnings made by hand according to instructions given in the article, ‘‘ Making a ‘Turned’ Spiral Pedestal,’”’ in the April, 1924, issue of POPULAR SCIENCE MONTHLY. There is nothing particu- larly diffi- cult either about this or any other part of the sufficient careis taken with the small details the com- pleted piece is a desir- able addi- tion to the Unique stand with spirally turned legs furniture of any home. Any good cabinet wood may be used; in this case oak was chosen. The four legs first are turned in the lathe. The spirals are cut by hand, as described in the article just mentioned, except that the circumference, instead of being divided into four equal parts to give a four-strand section, is laid off into 13 equal parts to give 13 strands. stead backsaw for cutting the depth of the it strands, a parting [ chisel was used, but of using a - Le’ a 1" CE AON ALL FOUR SIDES meen In- Ly Y ays stand, andif , Ornament Graceful Stand Have You Joined the Order of Home Craftsmen? N ASTONISHING range of craftsmanship is shown in _pho- tographs sent to the Home Work- - shop Editor by readers of Poputar Science Monrnuyry. Some of the pictures illustrate articles made by men who have had no training in woodworking. Certain Home Workshop designs caught their fancy and, gathering together whatever tools they could find about the house, they made the articles with a success that surprised them- selves and their families. Other photographs show the work of skilled craftsmen, who, with the keen judgment of experience, look constantly to the Home Workshop for new ideas. striking example of this type is the stand illustrated and described on this page. If you are not sharing in the great enjoyment that readers of the Home Workshop get from their work at the bench, why not start to make some- thing yourself, no matter how simple? You will find, like all the others who have taken up this hobby, that en- thusiasm in home craftsmanship, once aroused, is quite irresistible. pine. The bottom proper without the molding is composed of two pieces glued together, one 4 in. thick, of the same wood as the stand, and the other, of 1%-in.-thick An appropriate stock molding is mitered around the bottom after assem- bling. The parts are put together with CX ae Sento 3 ap alt SECTION A-A Ri = = vere amessasideacenes - {a N ae) Ee ; ° ot +{— 18% ja -1 good glue, screws wees and small brads. 4— 1244 —ws Either a wax ora ES oes varnish finish may thi) THICK be vsed, as pre- ferred. F YOU missed the article on the other two legs or isi wel hand-made spiral i SIDERAILS |» . “ At . into adjecent aides Eat au (TS, iy ae Baca to take the tenons | UE =a ke 4p — a you m~ ; hee , he side rails and Sy. copy ©. e April, tha rail 1 saat Dawe 1924, issue of ; ae ‘; POPULAR SCIENCE : ; a MONTHLY from HE top is fast- : the Circulation ened to a mitered frame, as indicated. The drawer runner also is a frame. It is made as shown and a %%-in. half round bead is added after the runner is fas- tened to the leg. The middle shelf is finished with a similar bead. The ornamental pieces below the middle shelf are identical,'except that the front one (and back one, if used) Department for #0 cents, the regular - t Piao I216LONG Me ite LF Working details of the is 121% in. long © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. I" SQUARE SE HALFROUND ow 3 cod 2RQIOZLONG Se = x i rapidly becoming i some issues cannot be obtained at and the two side pieces are each 101% in. ail. price for back copies. Every home worker should make a point of saving his back copies of POPULAR SCIENCE MONTHLY, or at least clippings of the articles to which he may wish to refer at some later date. The back copies of the magazine are exhausted 4 leg turn- ings, top, framework and drawer f. wall

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1925 ee fee me ee Poe rissed spiral ‘red to 10nds, ain a April, ‘e of IENCE from ation for 40 gular D1eS. worker oint of copies CIENCE t least articles yy wish e later - copies ne are ned at March, 1925 POPULAR SCIENCE MONTHLY 109 Fepoard of 100 uses Aside from its use for walls and ceilings, Upson Board has 100 uses around the home. Its easy work- ability makes it ideal for making wardrobes, photo- graphic dark rooms, cabi- nets, doll houses, waste- baskets, lapboards, tables, toys and countless other usefularticles. Youshould have at least a half dozen panels in your home workshop all the time. Impartial tests prove Upson Board superior! Harder, Stronger, Stiffer ! Here is a remarkable test that proves the greater strength of Upson Board as com- pared with plaster or gypsum-filled boards, Over 1000 pounds sustained by a single panel of Upson Board! Gyp- sum-filled board broke with less than one- third the weight. Upson Board is not brittle—it cannot crack or fall! More water-resisting! In another very conclusive laboratory test, Upson Board im- mersed in water for a * given length of time gained only 14 ounce to the square foot. sum-filled board exposed to the same test increas- ‘a ed nearly 14 pound to the square foot, Other wallboards tested in the same way were found to absorb nearly twice as much water as Upson Board. HA you see or hear of color used as an identification of wallboard, think of lable Upson Board with its famous Blue center © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. BLUE CENTER - The wonderful new Upson Blue Book the first complete service to help you renew and beautify HE new Upson Blue Book—al- ready in the swe of most Upson dealers—brings to “Popular Science” readers the most amazingly complete plan service for permanently renewing and beautifying walls and ceilings. Forty “detail plans” — designed by several of America’s leading architects —show you how to achieve the much- desired beauty of tasteful interior pan- eling. A host of suggestions for decoration and trim help you to finish each room in the most appropriate design. Pages of pictures show pos- sibilities in furnishings. walls and ceilings Whether you are repairing or build- ing new—you will want the inspira- tion, new help, of this wonderful new Upson Blue Print Service. And you will want to know more, too, of the distinctive beauty of properly paneled Upsonized rooms. Ask your lumber dealer to show you this wonderful new Upson Blue Book. If he hasn’t it, send us his name and 25¢, and we will send you full-size, detail blue print with com- plete instructions for Upsonizing any room. (State kind of room and whether new work or remodeling.) THE UPSON COMPANY 327 Upson Point PROCESSED Lockport, N. Y. °°, *. oe a ee, "eee, . nS — wee eres ner ise Peete oor Se ' if Sb

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110 “It suits me, and I’m hard to please!” Some smokers are apparently easy to please and easy to suit in their pipe to- bacco. There are plenty of brands for them. Edgeworth is made to suit the hard-to- please smoker—in fact, for those who might call themselves connoisseurs, if pipe-smokers ever did apply so high- sounding a term to themselves. Mr. Burrow, while modestly regretting his avowed lack of equipment as a testi- monial writer, speaks volumes in one trenchant sentence. Here is his letter: Larus & Brother Co., Richmond, Va. Gentlemen: Were I possessed of a gifted power of speech, a trenchant pen, and a Harvard vocabulary, I’d dash off to you a prosy sentiment extolling the virtues of Edge- worth. However, it suits me—and I'm hard to please! This—after many unsatisfactory at- tempts to suit my sensitive palate. My POPULAR SCIENCE MONTHLY 4 SS P OU will encounter no difficulties in the construction of this simple hall or living-room table. A good saw, Oa brace and bits, plane, hammer, nail-set, l4-in. chisel, sandpaper, file, and pocket- knife are the only tools needed. The following material is required: records of purchase will bear me out that it satisfies me, and I’d go a long way for Edgeworth. Very truly yours, G. M. Burrow Edgeworth in a way is similar to the kind of men you form decided opinions of—perhaps favorable, perhaps unfavor- able. But the point is, the very character of such men forces you to a definite opin- ion, one way or the other. Edgeworth is pretty much that kind of tobacco—smokers either like it immensely or not at all. Let us send you free samples of Edgeworth so that you may put it to the pipe test. If you like the samples, you'll like Edgeworth wherever and when- ever you buy it, for it never changes in quality. Write your name and ad- dress to Larus & Brother Company, 10C South 21st Street, Rich- mond, Va. Edgeworth is sold in various sizes to suit the needs and means of all purchasers. Both Edgeworth Plug Slice and Edgeworth Ready-Rubbed are packed in small, pocket-size packages, in handsome humi- dors holding a pound, and also in several handy in-between sizes. We'll be grateful for the name and ad- dress of your tobacco dealer, too, if you care to add them. To Retail Tobacco Merchants: If your jobber cannot supply you with Edgeworth, Larus & Brother Company will gladly send you prepaid by parcel post a one- or two-dozen carton of any size of Edge- worth Plug Slice or Edgeworth Ready- Rubbed for the same price you would pay the jobber. If you can have the wood dressed to size in the piece, it will cut the work in half. Sight along the pieces and trye them up, if there are any “winds” or warped portions. Test them with your try-square and plane them before cut to length. The legs, A, are 234 in. square and 24 34 in. long, including a tenon 34 in. long and 2 in. square. On the cross pieces, B, which are 3 34 in. wide, 134 in. thick, and 2 ft 2 in. long, measure back 13% in. from the ends and cut four mortises 2 in. square and 7% in. deep for the corresponding tenons on the legs, A. Also cut mortises 1 in, wide and 934 in. long in B for the tenons on the shelf, D. D is 1134 in. wide and 3 ft. 34% in, long, with 1-in. tenons added to fit the corresponding mortises in B. Blocks C are 414 in. wide, 334 in. thick, and 5 in. long. After fitting the shoulders of the tenons on A to the mortises in B and testing with the square, lay the legs aside and bore two 3/16-in. holes in op- posite corners of the mortises. Now lay B on the blocks C so that the latter project 14 in. beyond the former at the sides and ends. Mark through the holes with a pencil and bore ting 214 in. sq. by 10 ft. long, clear oak for legs, A 134 in. by 334 in. by 5 ft. oak for cross pieces, B 334 by 414 by 24 in. oak for foot-blocks, C i by 1134 in. by 4 ft. oak for shelf, D \4 by % in. by 6 ft. oak for ornamental nail heads 1 by 214 in. by 13 ft. poplar, gum, or soft pine for top frame members, G and H 1 by 14% in. by 514 ft. poplar, gum or soft pine for cleats, E, and cross piece, F i by 12 in. by 8 ft. poplar, gum, or soft pine for top 8 No. 16 screws 3 14 in. long No. 18 %4-in. brads Sixpenny finishing nails Glue Imitation leather 1 yd. wide, 5 ft. long , The table and de- tails of its con- structioa corresponding holes through the blocks, C. Counterbore the holes from the bottom exactly 2 in. with a 14-in. bit. After marking and boring corresponding 3/16-in. holes in the tenons of the legs, you are ready to screw the 10 pieces firmly together. Apply glue to the tenons of the shelf, D, place it in position, drive it home, and tack it from the bottom with small nails. The top frame may be built with square (Continued cn page 122) © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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p ed to ork in | true is”? or - your utting quare tenon ch are d 2 ft. 3¢ in, ortises ep for on the Y in, B for , Dis 4 in. ded to ortises . Wide, g. lers of ortises h the le and in op- rtises, s C so Y in. e sides gh the 1 bore ycks, C. bottom After 3/ 16-in. rou are firmly helf, D ’ .e, and ll nails. square —— nh , ‘Two thoroughbreds! That’s what they are —made for the craftsman that buys the best, when he adds a tool to his chest. A V & B Vanadium hammer you'll want to buy. They are made from special V & B formula vanadium steel, and handled with the finest hand-shaved, second growth white hick- ory. Octagon necked, and round faced—with a special non-slip claw, that firmly grips either a brad or a spike. A Vaughan’s Expansion Wedge firmly locks the handle tight—is posi- tive insurance of a tight head. You'll want, too, V & B Unbreakable Planes. They are drop forged—not cast— ‘from a solid bar of V & B supersteel. Stand the falls that would break an ordinary plane. Furnished with all vanadium steel blades and walnut handles, in the sizes you will want. Two tools of particular merit—get them for your kit! : VAUGHAN & BUSHNELL MANUFACTURING COMPANY O“Wakers of Fine Toots 2ili4 Carroll Ave.~ ~ Chicago, Wh: US. A. POPULAR SCIENCE MONTHLY © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. bs aici Ask your hardware dealer to show you V & B Vanadium Ham- mers and Drop Forged Planes. If he carries fine tools he has them. They’re the kind of tools fine craftsmen like, the kind it pays to buy.

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See How Soon You Can Start A Fortune Make This Test No matter how small your income now is, if you know how, you may become financially independent in a very few years. A valuable book — now free—will enable you to make the test which is showing hundreds of ambitious mentheroad to success. Here is a plan that will make it surprisingly easy for youto build up a comfortable sum—and in a comparatively short time. For years large investors have known how to build up fortunes with absolute safety—through legitimate investing. And now anyone can accum- ulate a fortune in exactly the same way. Thetested plans of experienced, successfulinvestors are now availableto the smaller investor. Through follow- ing their methods you can double your money ina little over ten years by investing in the safest securities possible to buy—First Mortgage Real Estate Bonds. In an unusual book you are told exactly how to discover the fortune that lies hiddenin your salary. It tells you how much to set aside each month to accumulate $10,000, $25,000, or even $50,000 in a certain time. It outlines an unusual plan for the scientific accumulation of money. It shows how you can create a good sized estate through invest- ing in Forman First Mortgage Real Estate Gold Bonds—all without risk or speculation of any sorte Mail the request blank for your copy. GEORGE M. FORMAN & COMPANY 105 W. Monroe St. Dept. A-833, Chicago 100 E. 42nd St., New York 40 Years Without Loss to a Customer GEO. M. FORMAN & COMPANY 105 W. Monroe St.. ‘ Dept. A-$33, Chicago, Ill. Please mail me with- outcostor obligation, a copy of your Free book, which contains tested plans for Building a Fortune.

eeeseecesseceee POPULAR SCIENCE MONTHLY

HILE “‘toe-in” is perhaps the most impor- tant of the three fundamental elements of design in a front axle as explained in the January issue, caster and camber are like- wiseimportant. They are, however, farless understood by the average driver, for they are designed and built right into the axle. Camber is illus- trated below. By Ray F. Kuns Principal, Automotive Trades School, Cincinnati, Ohio be straightened OF re- placed entirely, Caster is provi by the car builder when he arrange spring mounting in such fashion ag to throw the top of the pivot pin back of the bottom of the pivot pin, as indicated jp the illustration below. Not a great deal of caster is required, but its benefit is evidenced when, in rounding a turn

Engineers have built this into the + axle in order to ' insure long life of spindles and bear- ings, as well as ease and safety of steer- ing. Since most artillery type wooden wheels have been built with a dish, the camber allows the weight coming on the tire and spokes to be transmitted in a direct vertical line through the hub and spindle bearings to the spindle body. With the present-day tendency toward wire and particularly disk wheels, this feature is of lesser importance, except in bringing the load more nearly under the king-pin or pivot pin in the steering knuckle. This prevents road shocks from being transmitted to the steering wheel. If one carefully observes approaching cars, the camber will be visible. In the case of the Ford car, the camber is about 3 in.; that is, the tops of the front wheels and tires are 3 in. farther apart than the tires at the bottom, which is approxi- mately 56 in. from center to center where they are in contact with the road. INCE this feature cannot be built into the rear wheels, the stripped chassis has the appearance of having a wider tread at the front than at the rear. When a car has been overloaded to the extent that the front axle is sprung down- ward in the center, the camber is taken out. Looking at a car in this con- dition from the front, the bottoms of the tires show | farther apart than /| the tops. This | puts a dangerous ; amount of strain on the spindles and front-wheel bear- ings, since’ the r — ¢'ti'2'10 3° ———-+4 CORRECT CAMBER

AXLE STRAINED

>. Re Monat CAMBER LOST DUE TO OVERLOAD OR ROUGH USAGE. Overloading a car some- times destroys the camber Camber and how it is lost point of contact on the street is so far

removed from a vertical line through the pivot pin. There is only one way to put camber back into the front axle, once it is gone. The job must.be rebuilt; if the bushings are worn, they must be replaced; if spin- dle bodies are strung, they must be re- placed; if the axle beam is sprung, it must

in the road, front wheels aline them- selves with the straightaway with out assistance from the driver. Caster often js lost through the flattening of the front springs. Hay- ing them re-arched sometimes will help. In some cases it is well to make a steel block or wedge as__ illustrated. This is bolted up under the bottom leaf of the spring with the thick part of the wedge to the rear end. When the spring clips are drawn tight, the wedge will throw the top of the pivot pin back and the bottom forward. Again, in the case of a Ford in which the ‘‘wishbone,” or front radius rod, has

Se mu | a TRON WEDGE PLATE Lg <akey \? PLUMB LINE Using an iron wedge to restore caster, and testing with a plumb line been sprung through striking the curb or}. bad ruts, the caster may be gone entirely. In this instance, indeed, the top of the king-pin may be ahead of the bottom. So serious is this condition that it is folly to attempt to use the car, since it will get out of control quickly. The safest thing is to replace the radius rod with a new one, thus insuring the proper amount of caster. When this is not possible, the rod may be straightened and a test of caster made with a plumb bob, as shown.

A NEAT and serviceable check strap for an automobile door can be made from two strips cut crosswise from an old inner tube and trimmed to the proper size to fit the U fastener already on the car. One rubber ring is slipped inside the other to give double strength.—C. C.

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

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arch, 1925 POPULAR SCIENCE MONTHLY ‘Automatic Tools! Here’s a great line— Let me show you.” Epon is the way Millers Falls sales- 1 men show our Automatic Tools to the hardware trade. We only wish we could put this sample roll before all you men who prize the best tools for the sake of the best work. These fine automatic tools of ours are new enough to have all the good fea- tures, old enough to be thoroughly tested—but you know Millers Falls. Here’s the line at a glance: Spiral Ratchet Screw Drivers—3 sizes —with and without Automatic Return. Automatic Drills—5 styles. Ratchet Screw Drivers—3 styles—sizes for everything. Chuck and Drills—for spiral ratchet screw drivers. Socket Wrenches—for “Radio” ratchet screw driver. Names and descriptions don’t tell half the story. You ought to see these tools. Look them over in the hardware store. You’ll probably want all of them. Those you buy you'll like better and better the longer you use them. Send for circular describing our Automatic Tool Line MILLERS FALLS COMPANY © Millers Falls, Mass. 28 Warren St. 9 So. Clinton St. New York Chicago MILLERS FALLS TOOLS SINCE Samy, 1868 FS] This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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A Necessary “Tool” For Your Workshop OR the man or boy who has a home workshop, Lee Union-Alls are a handy “tool” to have about. All that is necessary when you want to get busy is to slip into them and start your work. They cover the body from head to foot and can be worn over other clothing. They save clothes, also. And they save time where the hours for such work are limited. Wear Lee Union-Alls, the original one- piece work suit, worn by thousands of mechanics,shopmen, garage workers and industrial workers. Lee Union-Alls are quality-built—close-woven cotton fab- tic;tiveted:rustproof buttons, reinforced strain points—fully guaranteed to give satisfaction. They give solid comfort, long wear, and are neat in appearance. Accept no substitute—look for Lee onthe buttons. Thousands of live dealers sell Lee Union-Alls. Ask your dealer today! LeeUnion-Alls THE H. D. LEE MERCANTILE CO. Kansas City, Mo. Trenton, N. J. South Bend, Ind. Minneapolis, Minn. San Francisco, Cal Lee Overalls and Work Shirts are other items in the famous Lee line. ' They are quality-built, also. POPULAR SCIENCE MONTHLY March, 1995 \ HERE is great fascination in model- making. Such remarkably realistic locomo- tives, cars, boats, and machines can be made even by beginnerswith lim- ited experience and tool equipment that POPULAR SCIENCE MONTHLY has arranged fora series of articles on this subject. They are ad- dressed to beginners who never have made amodel. Although they describe the construction of specific models, they are really on the general principles of model-making. The methods can be applied in making many kinds of models. Indeed, a model-maker hardly ever cares to copy an existing model; he wishes to make something a little different. That is the charm of amateur model- making — no two models are alike. This is the first ar- ticle of the series, which 1s the work of Edward E. de Lancey,anen- thusiastic model- maker of many years’ experience. ie THIS series of articles, I am addressing men and boys who are enthusiastic concerning railroad matters and are mechanically inclined, but have had no experience in model-making and possess only a meager outfit of tools. In making your own outfit according to your own ideas there is incomparably greater satisfaction than in merely col- lecting models. It develops ingenuity, patience, and forethought in a way pecu- liar'toiitself. Also, it enables you to make repairs or alterations under conditions that otherwise might lead to the laying aside or abandonment of a purchased model or mechanical toy. The accompanying photographs show what has been accomplished with a few purchased parts and a minimum of tools and money. I do not pretend to be The Home Workshop Simplified Railroad Model-Making By Edward E. de Lancey 2 machinist anq have never sessed a lathe op other machine tool, I never could do a thoroughly work. soldering, but, on the few occasions when it was unavoidable, have had it done for me. This is also true of the lettering on the cars. The 4-4-0 steam locomotive and tender shown at the top of the page was made before I ventured into electricity, but is shown as a matter of interest.. Its one tube boiler was purchased in London | in 1877 and its cyl | inders, eccentrics, wheels, and _ boiler fittings were bought in Boston or New York in following years. It has Ste phenson’s link mo- tion, a blower, and exhausts up the stack. Its gage, which is 3 in., was chosen unfortunately. Itis too wide for the best results and it com- pelled the adoption of the same gage for the electric locomo- tives, motor-trucks and Pullmans built subsequently. The drawings in the following articles, there fore, will show a gage of 21% in., but other- wise will represent a scale of 1% in. to the foot. These factors are a trifle inconsis- tent because your finished work will rep- resent a gage of 5 ft. instead of the 4 ft. 8 l4in.standard. This discrepancy will-not be noticeable except to a trained eye, but will make your work accord with a favorite model gage on both sides of the Atlantic. I suggest that you stick to the 214-in. gage throughout. It.might prove he)pful should you have an offer for your work. In the next article I shall show a form of motor-truck that, with such adapta- tions as your resourcefulness may suggest, will suit any small motor. The 'locomo- Commuters’ tive and bag- cer and Pull- gage car man ‘(left); below ‘both electric loco- have an eélec- mctive and tric drive car (below) How to Cut a Glass Circle O CUT a circle of glass from a square piece, first mark the glass with a cir- cular glass cutter and then mark four diagonal lines with a straight glass cutter from the circumference to the corners. © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. Turn the glass over on a flat surface and tap lightly with a pointed tool such as a cold chisel just over the markings. Witha little practice, it will be found quite easy by this method to accomplish apparently difficult feats in cutting glass.—ERNeEST T. ADAMs, Fort Monroe, Va. ——

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8 t and ne, le tool, id doa work. job of ut, on Casions it done ttering tender 3 made but is its one. uondon its cyl- entrics, boiler bought r New llowing as Ste- 1k mo- er, and D the rhich ig chosen y. Itis he best t com- loption age for ocomo- -trucks . “ene there- ; other- , to the .consis- ill rep- he 4 ft. will not ye, but avorite tlantic. n. gage should a form \dapta- uggest, nuters’ d Pull- (left); > loco- » and below) ce and ch as a With a te easy arently jEsT T. For the man who works with tools for the fun he gets out of it—three pairs of Klein’s will about do. Ask your hardware dealer to show you 4 pair of 8" Klein’s Side Cutting, and a pair of 6" Klein’s Oblique. You'll need as well a pair of 6" Klein’s Long Nose. Your hardware dealer carries a full line—look them over next time you are in! '{S) This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. POPULAR SCIENCE MONTHLY HE pliers in your tool box come near being the most all-around useful tools you have. No wonder you fellows are particular about them, when you buy! The man who works with tools for the pleasure he gets out of it can’t do better than to take a tip i from the professional electrician and the skilled mechanic. They prefer Klein’s! Naturally there is a reason. The shape, for instance, of any Klein Plier is the result of years of design and redesign. The keen knives are indi- vidually tempered to keep their cutting edge for years of service. The easy spring of the handles i and the balance of the tool is made just right for na maximum comfort. Every Klein Plier is drop- ot forged from tool steel, and each process of its manufacture is subject to exacting inspection. Face po renner cerca peeumtar seers 5223s They are gluttons for punishment and will last you for years! Mathias ‘Established 185

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116 POPULAR SCIENCE MONTHLY March, 1935 | | | FREE 1925 ATLAS With Maps o/NewEurope To readers of this magazine who take advan- tage of this offer now made in connection with Webster’s New International Dictionaryautherity” A complete reference library in dictionary form, with 3000 pages and type matter equiva- lent to a 15-volume encyclopedia, all in a single volume, can now be yours on the follow- ing remarkably easy terms: The entire work (with FREE 1925 Atlas) DELIVERED FOR $1.00 and easy monthly payments thereafter (in United States and Canada). You will prob- ably prefer the beautiful India Paper Edition which is REDUCED ABOUT ONE-HALF AN THICKNESS AND WEIGHT AS COM- PARED WITH THE REGULAR EDITION Over 407,000 Vocabulary Terms and in addition, 12,000 eo on Names, nearly 32,000 Geographical Subjects, 3,000 pages. 6,000 Illustrations. Constantly Im- proved and Kept Upto Date. Copyright 1924. To have this work in the home is like sending the whole family to college. To have it in the office is to supply the answers to countless daily questions. To Those Who Send This Coupon \ aa ae ee G. & C. eal ss MERRIAM CO., KN cX\ x Dept. S, Springfield, Mass. - Please send me free of all obligation or expense a copy of “Dictionary Wrinkles” containing an amusing “Test in Pronunciation’ (with key) en- titled ‘‘The Americanization of Carver’’; also ‘125 Interesting Questions’ with references to their answers, and striking ‘‘Facsimile Color-Plate’’ of the new bindings. Please include specimen pages of India and regular paper with terms of your free Atlas offer on Webster’s New International Dic- tionary to POPULAR SCIENCE readers. Exhibit Your Invention oont the... EXPOSITION of INVENTIONS Write for information THE AMERICAN INSTITUTE OF THE CITY OF NEW YORK 47 West 34th Street, New York City 4, ZIP-ZIP "THOUSANDS of boys are made happy with this won- derful Zip-Zip shooter, something every boy wants and never gets tired of. Ep-tle shooter is scientifically and practically made; boys, if you like hunt- ing and outdoor sports —_ a Zip-Zip shooter with plenty of pep and force and learn that quick and sure aim. If your dealer happens not to have em, orde rom us. Zip-Zip shooter I 35c or three ‘The Home HIS oak bench is a useful piece of fur- niture in almost any room or nook, espe- cially in the hall, in front of a fireplace or before a window. The seat board, A, is 1 by 14 by 24 in.; the top rails, B, are 1 by 3 in. and have beveled ends so that the top and bottom edges measure 19 and 1914 in. respec- tively. The end boards, C, are 1 in. by 11 An Inglenook Bench of Simple Design By J. T. Garver have faces 114 by 2 in, After the bottom rails F, are cut 1 by 2 by 26 in., the parts may be assembled in their relative positions and any fitting and beveling done to make the joints perfect. The top edges of the parts C, D, and E are beveled so that they are level with the rails B. The parts B, C, D, and E then are placed in their proper position on the bottom of the seat board A and are held in place temporarily by An attractive yet easily made bench for the fireplace or for any inglenook driving small nails through their inside edges. Now mark the edges of C 3 in. up from the bottom, lay on the : bottom rails, F, and cut tenons in them and corre- sae sponding mortises in C at the proper angle. When these tenons are driven home, the | in. wide at the top and 14 in. wide at the bottom. They are sawed out to a depth of 3 in. at the bottom to form the four feet. The oval holes and scrolls are sawed with a coping- or jig-saw. The pattern for one- half of these ornaments first should be drawn on paper or cardboard and cut out or folded over so that the other half may be made perfectly symmetrical. The cleats, D, are 1 by 114 by 9 in., and, after being fitted, are bored with a 3/16-in. for $1.00; send stamps, coin or money order. = | SCrews. AUTOMATIC RUBBER CO., Dept. 22, COLUMBIA, S.C, | bit and countersunk for 114- and 2-in. The four triangular blocks, Z, inside measurement between the top and bottom of the end boards, C, will be 19 and 23 in. respectively. Four triangu- lar pieces, G, are fitted in the outside angles of F and C. Glue then is applied and the screws are driven home. Any surplus glue should be scraped off carefully. After the glue sets thoroughly, the piece should be well sanded, all sharp edges rounded off and stain or die applied. The wood then is waxed and rubbed thoroughly, several coats being given. © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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2 in. ails, may ions 1ake the they arts heir seat held y by nails iside dges 1 the the , F, 1s in orre- tises roper Vhen nons iven the yp and be 19 iangu- utside Ws are yuld be y, the sharp pplied. rubbed ren. —— — Ir is difficult to appreciate the difference between a Simonds saw and an ordinary saw — until you get BEHIND a Si- monds. THEN you will find that Si- monds steel, Simonds design and Simonds workmanship have combined to produce a saw thatSINGSits way through POPULAR SCIENCE MONTHLY SIMONDS BLUE RIBBON HAND SAWS a board quickly, cleanly and easily. TheSimonds Blue Ribbon saw is typical of the quality that Simonds has been putting into cutting steel since 1832. The name Simonds on the blade of ANY cutting tool is your guar- antee of quality. It will pay you to insist upon a Simonds saw. SIMONDS SAW AND STEEL COMPANY “The Saw Makers” Fitchburg, Mass. Established 1832 Branch Stores and Service Shops in Principal Cities SIMMONDS Pronounced S!i-MONDS CE RRO SAWS FILES KNIVES STEEL FS] This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. Sa aa panrnisee 29> cee ere tae sins as ey Senin pannus fit nnn a cores ng 3 arenes’ at eae = 5 Siete ae

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POPULAR SCIENCE MONTHLY

Could she earn her own living ? HE’S your daughter—and per- haps you hate to think of her having to work for a living. But this sort of thing does happen in very nice families — and too often the girl is’ utterly unpre- pared for any well-paid occupa- tion. So she takes a poorly-paid job as sales girl, waitress or clerk. * * * * It’s different when there is a Corona in the home. A child who has learned to use Corona Four, with its standard office keyboard, can operate any office machine — and you’ve provided her with the best kind of an insurance policy against the day when she may be forced to sup- port herself. Corona Four costs only $60. Easy terms if desired. Look for Corona in your phone book or write Corona Typewriter Co., Inc., 112 Main St., Groton, N. Y.

RADIO Storage “B” Battery 32 Gens 33 fore Lasts Indefinitely— Pays for Itself ‘ormance unheard of before. Rec harged Approved gnd listed_as Standard by 1 —, ‘op. Radio Laboratories, Pop. tc fax, Inc. and other im- portant institutions. Feu with Sold Rubber Case, an insur- _ — acid Too! e. pare heavy ay = jars. Heavy FR yours today’ SEND NO MONEY 3 Just state number of batteries order is received. Extra 74 batteries in series (96 volts), $13. ue e prosseaan after examining batte batteries. 6 per cent discount for WORLD BATTERY COMPANY 1219 So. Wabash Ave., Pert. 80; Chicago, Ill. Pe. ‘eval pg my 32.607 2 120 0 Amp, $1 4s. poe. Pat t6.00. pon U equipped with "® at rye ible ‘ost. ae ioe Standards,

\Wo rl do. S oh ® ATER

The Home Worl How You Can Make a Round Frame Solidly carved effect obtained easily by unique method of built-up construction LABORATELY carved as it ap- pears to be, the picture-frame illustrated presents no great diffi- culties in construction. Any amateur woodworker who is willing to take the necessary time and pains can duplicate it. That is because its delicacy and beauty are not the result of carving the

This circular picture-frame of rich appearance can be duplicated without much skill in carving design out of the solid, but of building up the frame in sections. Although cherry was used, almost any close-grained cabinet wood will serve. The four main segments are cut with a compass saw from stock 11/16 in. thick so as to form a frame 4) in. wide and 2334 in. in diameter. If available, a bandsaw or jigsaw may be employed to good ad- vantage for sawing these. Smooth the segments carefully with a spokeshave and sandpaper. Using a sharp knife, router, and gouge, cut the edges of these parts, which are to form the front frame, to the correct profiles and make the 4-in. deep channel, as indi- cated in the working drawing.: The back frame is composed of four segments 34 in. thick and 334 in. wide. These are fastened to the heavier seg- ments with glue and flat-headed wood screws from beneath. The keystone-shaped pieces that cover the joints of the front frame are let into corresponding mortises cut \% in. deep. The design on the keystones is cut with a small chisel and the background is roughened with a nail filed as shown. The main border design, one-quarter of which is shown, is cut out from stock \ in. thick, the saw following the heart-shaped outline of each unit of the ornament. One segment is glued in each of the four circular recesses of the main frame and then the leaves are carved slightly on the surface, as made clear in the photograph. The frame may be finished in any way desired, but the one illustrated was var- be: eQ S GILDED ee .— \ \ F a st i]s "FRONT FRAME Z CESS I 7 SEGMENTS Vg DEEP + x nished and then gilded where marked in the drawing below. Finally a piece of picture glass 1534 in. in diameter is fitted into the rabbet and the picture framed, Following the same general principle of construction, frames may be made any size needed and either delicate or heavy, as best suits the picture to be framed.— WILLIAM J. EDMONDS, JR. KEYSTONE PIECE _—_— __

Vy" 42 3," 5 yl Way "| =P recess FOR DESIGN Ya" {;. s 4 4 = | FRONT FRAME A ee ¥ 7%, BACK FRAME xe :

~ Details of the front and back frames and method of applying the carved ornamentation Old Music-Stand Is Converted into Ornamental Tea-Wagon AN INDI- CATION of what can be done in con- verting old and useless pieces of furniture into articles of real value is given in the ac- companying photograph. This is a tea- wagon made . from an‘ old walnut music-stand with fretwork ends. Part of the legs were cut off to make the top 30 in. high, rails put on under the top, and a drawer added. The additions] | were made of walnut and the whole piece was refinished with shellac and wax.—H. CALDWELL, Toronto, Can.

WHEN whitewashing, add a little salt or kerosene to the mixture. This will help prevent the whitewash from rubbing off. ——

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

See page 33.

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ch, 1995 me <ed in ace of fitted led. ple of e any leavy, 1ed.—

| with . make ler the ditions | e piece x .—H. salt or 1) help ng off. March, 1925 LAATERIPIG LW ALES SE ARR

el

POPULAR SCIENCE MONTHLY 119

eet ‘Porter's | Bolt Clippers o? Wir @ Cuttess Husky, two-handed tools for cutting rods, bolts, heavy wire and chain, and for splitting nuts. Capacities up to 34" annealed bolts in the thread. Time and money savers. every Workbench

iy Yip) ny 7H |\ . VALAIS SS —-

PORTER Bolt Clippers in a variety of sizes and with a number of types of cutting heads, are sold by retail hard- ware stores, tool stores, accessory dealers and imple- ment stores every- where and are car- ried in stock by leading hardware jobbers all over the United States. Ask your dealer—‘:e has PORTER Clippers or he can get them guickly.

H. K. PORTER, Inc. Everett, Mass. ff van ~N JE

ly A quickly andeasily, \\. SRO | WeSA 2 PORTER Bolt Wye IS} e ipper saves the Ba a aa \\ i 1“ Wy day.” \ Wai) iN, /7 RY \ _— | \\\ AN, Rah i Nt tly eH | Win \\\ \\\ . yy. I, ae at Ry el ' Vescrmas -_ — \=\ and telephone work, building-wrecking, a PORTER Bolt Clipper will come in handy for a hundred and one jobs, from cutting curtain rods to fender bolts. They are used on production in th-usands of factories and power plants, on building and construction work and in garages __ everywhere. They are invaluable around the farm, machine shop and on the home work-bench.

—ee’

CHAIN CUTT

E —— SIDE CUTTER 4

NUT SPLITTER

LAR CUTTER In every Tool-Kit~ the PORTER Bolt Clipper meets emergencies— on railway maintenance and construction, telegraph AN GU ‘ fire departments, road-building, lumber / P camps, mines, shipyards— y wherever heavy rod, bolt, chain and wire cut- , ting is to be done ™\ % A\ uN

calles 7 A | en, /

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

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POPULAR SCIENCE MONTHLY

THe Around the World Fliers took nothing for granted---they included NICHOLSON Files in their orignal equipments, Yet these aviators could have obtained files bearing the NICHOLSON crossed- file trade mark at most stopping points on their lengthy flight ! Y Around the World--in every nation where high-grade tools are necessities USA. in industry--NICHOLSON Files are on sale. NICHOLSON Files cut sharply from ks the first stroke. Every one is a sa mechanically perfect tool, made with great skill and care’ of the best grade of file steel, then repeatedly tested to iS assure its reaching your hands entirely free from defects. Your Hardware dealer sells NICHOLSON Files. Let him help you select those your req oe oll NICHOLSON FILE CO. Providence, R.1., U.S.A. iINICHOLSON FILES ~a File for Every Purpose

IS} This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. March, 1925

= i F he Home Wo

Blueprint Contains Details of Kitchen Cabinet Work-Table

i THE kitchen a convenient, well. designed work-table is as important ag a substantial, well-built bench is in the shop. To build one is not especially diff. cult, provided a good design is followed, such as that contained in Blueprint No, 27 in the Home Workshop series below, The new blueprint for this month (No, 40) is a writing-desk in Sheraton style, This is illustrated on page 98.

Complete List of Blueprints A NY one of the blueprints listed below can be obtained from POPULAR SCIENCE MONTHLY for 25 cents. The Editor will be glad to answer any specific questions rela- tive to tools, material, or equipment. Blueprint Service Dept. Popular Science Monthly 250 Fourth Avenue, New York GENTLEMEN: Send me the blueprint, or blue- prints, I have underlined below, for which I inclose..... eV 10a dae cents: No. Title Price ee eo 25¢ 2. Smoking Cabinet, ......5 0000 0s808 25¢ 3. Book Trough End Table........ 25c ee Sie Ye OTS re 25c 6. Two-Stage Radio Receiving Set. .25c BS. RVI WMC as 65.6 oct cee ces 25 9. Arbor with Gate and Seats ec | re oa 11. Bench and Tilt-Top Table....... 12. Electric Washing Machine....... Ee OE Ae ee 14. Toy Train, Horse, and House... .25c 15. Home Workshop Bench......... 25c 16. Inlaid Radio Cabinet........... 25c 17. Cedar and Mahogany Chest..... 25c¢ 18. Telephone Table and Stool...... 25¢ 19. Grandfather’s Clock............ 25c yt ae yoo br 25c 21. Colonial Writing-Desk.......... 25¢ 22. Girl’s Cabinet and Desk......... 25c 2S. PECROIA CABTORE 6 66.555 0c cc ccsces 25c Ps ge) Ce eer 25c¢ 25. Sailing Outfit for Canoe......... 25¢ 26. Baby’s Crib and Play Pen....... 25c 27. Kitchen Cabinet Work-Table... .25c 28. Pullman Play Table...........°. 250 29. Toy Tea Cart, Garage, etc....... 25¢ 30. Tool Cabinet, Bench Hook, etc. ..25c 31. Priscilla Sewing Cabinets. .......25c 32. Chinese Game Table............ 25¢ 33. Pullman Dining Alcove......... 25c 34. Trellises for House and Garden . .25c , 35. Simplified Radio Cabinet........25c 36. Rush-Bottom Arm-Chair........ 25c 37. Simplified Bookcase............ 25c Fe SS eas oo) ee oe era 25c 39. Salem Chest of Drawers......... 25¢ 40. Writing-Desk in Sheraton Style. .25c TVMIEE. Sc SGN SG Gain cas A" «5:2 < asawatnl ee (Please print) IPE 4 nw whe ales b.ns5 dice sie Sicln Cake a ee °

Ue a =

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POPULAR SCIENCE MONTHLY “Built- in Accuracy for Builders HE factory built-in accuracy of Sand’s Levels is permanent, therefore dependable. Workmen who value their reputations won't trust themselves to adjust a level—they leave that to factory experts. The accuracy of every Sand’s Level is sealed in and double sealed. You can bank on it now—you can bank on it ten years from now. A Level Is Known by the Company It Keeps

ies asia

permges se | & P SABA & << oO

Be ——- KAANnnnnne- —a SSSsssaacasg ot oy & 259 " ch) “ee Just peek in the tools kits of the master | craftsmen on any job—you'll find a Sand’s level most every time. Because these men know good tools, and because they won’t gamble with their own reputations by using anything else. i

START THE SEASON RIGHT WITH A SAND’S At Good Hardware Stores Everywhere

Wood and Aluminum Levels for Every Purpose SANDS LEVEL & TOOL CO. 5849 Fischer Avenue - - - Detroit, Michigan © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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We believe we make the best typewriter ribbon in the world —and its name is PARAGON e.. He has learned not to waste the minutes. Histrain- POPULAR SCIENCE MONTHLY Every SUCCESSFUL MAN KNOWS THE VALUE OF TIME inghas taught him touse every second productively. In this important factor of success he finds the Remington Portable an able ally. Away from his office it saves his time. It writes for him rapidly, legibly—and makes every writing task a pleasure. The Remington Portable has won a leadership, in sales and popularity, which is only natural. It has every feature of the big Remington but size. It has the full, standard keyboard; is easy to operate, and does beautiful work always. It is light, compact, reliable, durable—and it carries its table on its back, so you may use it anywhere, at any time. Remington Portable is sold everywhere. Easy payment terms if desired. Write today for il- lustrated ‘‘ For You— For Everybody.”” Address Department 67. REMINGTON TYPEWRITER CoO. 1 374 Broadway, New York— Branches Everywhere 4 emington ae \ Portable / X The Recognized Leader in 3 Sales and Popularity FS] This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. March, 1935 | preferably maple, 18 by 24 in. and at iene this odd-shaped breadboard, plane smoothly a piece of hard wood, least 1 in. thick. Draw the outline of the pig and cut it with a coping-saw, al. though it is advisable to have the board bandsawed if possible. Bore a 14-in. hole in the center of the tail, so that the board can be hung ong hook. Then rasp the edges smooth. Saw a small kerf for the mouth, work out the snout as shown, and burn in the eye, eyebrow, and curve of the tail with an old soldering iron or iron rod. Sandpaper thoroughly, finish with three coats of boiled linseed oil, and trim the edges with gray or blue paint or enamel.—J. ¢, WILLIS, West Kelso, Wash. Oak Hall Table (Continued from page 110) or beveled corner joints. The side pieces, G, are 214 in. wide and 4 ft. long; the end pieces, H, are 21% in. wide and 2 ft. 2 in. long. They are nailed to the legs in such a manner as to form a recess 1 in. deep to accommodate the top boards. The inside of the frame should measure 24 in. by 3 ft. 10 in. On the wooden top, when it is in place, is laid a piece of fiber-board 2 ft. 2 in. wide and 4 ft. long, without tacking. Dark green, drill-backed, imitation leather is cut 2 ft. 9 in. wide and 4 ft. 7 in. long for the top cover. It is lapped at the corners, pulled taut, and tacked every inch along the bottom edges of G and H. The 14 by 3% in. by 6 ft. piece of oakis cut into 76 blocks, 34 in. square. After being smoothed with file and sandpaper, these are set edgewise and split with 4 knife. The parts of each pair are kept together. Then the lower half of eachis bored or drilled with a small hole anda No. 18, 34-in. brad is inserted. Attach one of these blocks 1 in. from each corner, as shown. Then apply glue and stick on the outer half of each block. After the corner blocks are in place, mark the inter vening spaces into even intervals and drive in the ornamental “nails,” which can be done us you make them. These nails, as well as the imitation leather, are very durable. The table illustrated was built exactly according to these specifications and has been in every- day use for 12 years. If desired, the feet, C, may be recessed from the bottom to take concealed bal- bearing casters. The finish may be light golden oak or whatever oak stain is pre ferred.—T. G. ——— ti @ Bess = avera, it is e lifetin pital medic Thous MACF Dept. | 1926 B donna either 5 Iwill re Name. . Occupa: Residen City an Employ Business

Page 91

e of the aw, al- e board r of the ng ona th. Saw out the she eye, ch an old indpaper coats of iges with L—J. C. de pieces, ; the end 2 ft. 2 in. gs in such n. deep to [he inside 24 in. by s in place, 2 ft. 2 in. ing. Dark leather is n. long for he corners, inch along ce of oak is are. After sandpaper, plit with @ ir are kept f of eachis hole anda d. Attach ach corner, nd stick on After the *-k the inter tervals and ails,” which m. 1e imitation The table according to een in every stain is pre _—_—_————. > 33. March, 1925 ut ONE Person in Three Enjoys POPULAR SCIENCE MONTHLY CULTURE Good Health ij At least 60% of physical and mental misery is preventable and curable. In fact the life of most persons would be prolonged 15 years if they knew how to rule their health as they do their actions. people die of bronchitis, sixty-four thousand die of pneumonia, seventy- five thousand die of kidney trouble, fifty thousand die of respiratory disease, one hundred and six thousand die of tuber- culosis, approximately eighty-five thousand die of influenza, and more than ten thousand die of intestinal trouble. ; Barring accidents and suicides, only a small percentage of these thousands should di Fr eon year more than ten thousand e. It is a fact that only about one person out of three enjoys good health. And those who are physically a little “off’’ right now will more than likely be the ones to suc- cumb to preventable diseases this year. And they are the ones who should not die. Nature is constantly warning you of impending sickness. Seemingly trivial symptoms tell of serious troubles taking root in your body. And yet, ninety-nine ople out of every hundred will absolutely ignore these danger signals. As long as they are not flat on their backs, they will fool themselves into believing that they are all right. hire is merciless. If you do not under- stand her laws and her methods of prevent- ing and curing sickness, you suffer. She knows no excuses—she accepts no apologies. The Average Person Pays Thousands of Dollars in Doctor’s Bills Those who do not know Nature’s methods of preventing and curing sickness are ill an average of 2114 days each year. In fact, it is estimated that the average person in a lifetime spends $4,100 on doctor and hos- pital bills, loss of time from _ business, medicine and other expenses due to illness, Thousands of people are living half-powered YOLUME I lives because they are ignorant of the laws of Nature. Many of these people will fill an early grave, when they might easily have lived to enjoy a ripe old age. What would it be worth to you to be able to instantly identify in its earliest stages How to possess exhilarating health every day in the year know your own body eat for health diet for the cure of disease know the art of food preparation build a powerful physique correct physical imperfections become a physical director avoid unhappy marriages avoid disease fast as a curative measure cure by hydropathy (heal by the use of water) apply all methods, of drugless healing give first aid in emergencies apply home treatment for disease recognize diseases by manifestations build nervous energy treat the common forms of disease understand the process of reproduction benefit by laws of sex and marriage treat diseases of women diagnose diseases have healthy and vigorous children treat female disorders treat male disorders obtain virility and manhood care for the complexion manicure; care for the hair and feet cultivate the mind These are only a few of the matters ex- plained in the Encyclopedia. any sickness or disease that might overtake you or any member of your family? To enjoy perfect health, almost complete free- dom from sickness, doctor and hospital bills, ENCYCLOPEDIA of. PHYSICAL CULTURE New 6‘ Edition~ Completely Revised and no days of suffering and worry, or salary lost through sickness? La ee The Enc i MACFADDEN PUBLICATIONS, INC. 1 e yclopedia t. P.S.3, Macfadden Building 1926 Broadway, New York City Send me for 10 days’ inspection the five volumes of the Ency- Copedia of Physical Culture. If I find the set satisfactory I will cither send $2.00 in ten days and $3.00 a month until $35.00 has If I decide not to keep the books ' n paid, or $31.50 cash. will return them in 10 days postpaid. Foreign orders—cash in advance ee ee of Physical Culture This marvelous work gives invaluable information on fasting, diet, exercise, and hydropathy for both health and beauty building. It gives thorough and extensive treatment on the laws of sex, the attainment of virile man- hood and womanhood, and happy successful parenthood, together with details for cor- MACFADDENS WACFADDEN'S MACFADDEN'S MACFADDEN'S yacr FNCYCLOPEDIA ENCYCLOPEDIA ENCYCLOPEDIA ENCYCLOPEDIA OF oF OF - - ~~ YOLUMEM YOLUMEII 123 _ = po ~~ = ENCYCLOF i OF ‘ep PHYSICAL PHYSICAL PHYSICAL PHYSICAL paySicAL CULTURE CULTURE CULTURE cULTURE YOLUMEINV VOLUME Y rect diagnosis and treatment of all sexual diseases. It contains many handsome charts on anatomy and physiology. It is neither dull nor technical, but is comprehensive and complete in every sense. It is the crowning effort of Bernarr Mac- fadden’s rich, full experience in the science of health and physical culture. You haven’t any idea how valuable it will be to you, or how many dollars it will help you save each year. What, for instance, would it be worth in actual dollars to you to be able to in- stantly identify in its earliest stages any sickness that might overtake you or any member of your family? What would it mean to you to have glorious health, almost complete freedom from sickness or disease, no doctor’s bills to meet, no hospital bills to pay, no days of suffering or worry, no salary lost through absence from business? ‘‘One of the Best Works on Health Ever Published,”’ says one writer Thousands of letters have been written to Ber- narr Macfadden commending his Encyclopedia of Physical Culture. One (name furnished upon re- quest) says ‘‘Permit me to thank you for the great work by Mr. Macfadden—the Encyclopedia of Physical Culture—which I got from you some time last month. I have read much of it already, and con- sider it to be one of the best books on health ever published. I wish to thank Mr. Macfadden for his great work. The Encyclopedia is going to be my best doctor now and always.” Another man writes: “I cannot express the wonderful value of these great books and feel they will lead me to a successful married life, as I have recently married. They are a plain, sensible and priceless guide to a perfect physical life."’ A New Edition Just Off the Press Five big editions of this popular work have been exhausted. And now the sixth edition—greatest of all—has just come off the press. This edition has been completely revised at great expense. Scores of new illustrations have been inserted. The binding has been changed to a beautiful all Fab- rikoid, more durable than leather. Altogether it is the finest edition of the Encyclopedia ever issued. 10 Days’ Free Examination of Entire Set—No Money Needed This is the most liberal offer we have ever made on the Encyclopedia—10 days’ examination of the entire set at no expense to you. There is no money needed—no deposit to pay. Just fill in the coupon and we will send the five volumes to you, all shipping charges prepaid, for your inspection. Take ten days to examine the set. Then if you decide to purchase send us only $2.00 as your first payment. Additional payments may be made at the rate of only $3.00 a month until the total cost of $35.00 has been paid. Examine the Entire Set for 10 Days FREE ! a RO RE SS

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2668 Coyne St. ~. @ Anassurance that, when you try out a hook-up, you can rely on your instruments to give you a fair test. € A knowledge that each part has been put to such searching tests ‘that its proper performance, under any conditions, is assured. @ In short, a conviction that each individual part will continue to do its work year after year. Two pleasant hours spent with the RADIO KEY BOOK will acquaint you with the essen- tial facts of modern reception, and how to enjoy it at its best. Ten cents—coin or stamps — brings the KEY BOOK. RAULAND MEG. CO. Pioneers in the Industry Chicago POPULAR SCIENCE MONTHLY What Reliable Radio Means to You IS) ALLAMERICay Guaranteed Radio Products Standard Audio Transformers 3 to 1 Ratio, type R-12...$4.50 5 to 1 Ratio, type R-21... 4.75 10 to 1 Ratio, type R-13... 4.75 P Ampli Transf. ‘ower F atitying ‘ormers Input type R-30......... Output type R-31........ Rauland-Lyric Alaboratory grade audio transformer for music lovers.’ R-500..... Universal Coupler Antenna coupler or tuned r. f. transformer. R-140...... $4.00 Self-Tuned R. F. Transformer =e |S Wound to suit the «6——é+ tube. R-199$5.00. R-201A$5.00 Long Wave Transformer (Intermediate Frequency) (15-75 ke.) R-110......... $6.00 oF R uy Lg UA 10,000 Meter(30kc.) Transformer Tuned type (filter or input). R-120. .$6.00 Radio Frequency Coupler (Oscillator Coupler). R-130$5.00 Super-Fine Parts Consisting of three R-110’s, one R-120 and oneR-130,$26.00 /f Afl-American Reflex Receivers “ Complete ree ceivingsetswith extraordinary range, volume and selectivity. All parts |= mounted on Ss panel and baseboard, with full instructionsfor wiring. All-Amax Junior (one-tube)........ $22.00 -Amax Senior (three-tube) $42.00 Se Ow eas St hPa, Transformers in the World - Built directly out. side a cellar win- dow, this small handy hotbed can be cared for com- fortably. The plants are reached by standing on a bulb storage bin A Vest-Pocket Lighting Plant (Continued from page 106) and dash switches for each light. For! bright lighting 32-candlepower bulbs are | used, and for closets he uses 8-candle- power lights. Two chargings of 4 hoursa | week are usually enough to keep the bat- | teries fully charged. Two or three lights | are lit every evening. Two 120-ampere-hour batteries have sufficient reserve so that there should be no dull lights. At a 10-ampere charging rate, two days’ running will completely restore them. However, as one bulb uses only about 2 amperes an hour, one can see readily that in an evening very little current is drained from the batteries. It may be well to state that if the third brush of the generator is moved in the direction of the rotation of the armature, the charging rate can be increased, and vice versa. The system described has been in usea year and has given all the service that could be expected of it. It will not, of course, give sufficient current to operate flatirons, toasters, and the like, but it gives a clean, white light at very low cost. It saves the work of keeping oil lamps clean and is much safer. A Decorative Desk (Continued from page 98) FF Drawer-front rail, doweled, % by 2% by 24% whitewood, 1 required Runners (tenoned one end), 7% by 2 by 13%, whitewood, 2 required HH Drawer guides (nailed in), 14 by 1 by 13, whitewood, 2 required ie II Top of base, % by 18 by 28, 5-ply with veneered edges (or solid), 1 required Mortise locks, 11% in. to pin, brass selvage,2 required KK Socket casters, 214 in., brass, 4 required LL Veneer for bandings, 1/32 in. thick, mahog- any or walnut to contrast with other wood u MM Top fasteners, % by % by 1%, iron, 8 t quired NN Molding for interior, 10 ft., 1 required OO Draw knobs, stock, brass, 2 required PP Handles for top sections, if desired, stock brass, 2 required Hinges, 114-in. wrought-brass desk butts, 2 required RR_ Dowels, % in. diameter 1S] This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. eee Mare a i asi F are TI

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nt. For ulbs are 3-candle- | t hours a | the bat- ee lights ies have hould be charging mpletely oulb uses one can ery little series. the third 1d in the irmature, ised, and 1 in use a vice that ll not, of 0 operate e, but it low cost. oil lamps - » by 2% by oy 1 by 13, 5-ply with ss selvage, 2 required ick, m ‘ood u , iron, 8 fe quired uired sired, stock esk butts, 2 ——_—$—$—— Se POPULAR SCIENCE MONTHLY The Trimo Pipe Wrench is made with Steel Handles in sizes 6, 8, 10, 14, 18, 24, 36 and 48 inches. Made in Wood Handles in sizes 6, 8, 10 and 14 inches. | F you're a man who buys tools strictly on their merits and who cannot be influenced by the small difference of a few cents, here are 7 reasons why you'll want a TRIMO Pipe Wrench. I. You can make your TRIMO last for years and years because ALL of its parts are renewable. This feature alone (especially of the INSERT JAW in the handle) makes TRIMO the cheapest wrench in the long run. You know how annoying it is to have a wrench lose its adjustment in close quarters. —2TRIMO won't do that—the nut guards prevent it. Wrench frames sometimes break when put on a tough job. TRIMO’S won t—its frame is made of specially tested steel. TRIMO means SAFET Y—always. TRIMO’S long, steel handle guarantees extra leverage—less exertion— less hard work. Run your fingers along TRIMO’S deep-milled teeth—they WON’T SLIP—yet they WON’T LOCK on the pipe. Take a TRIMO in your fist—its perfect balance fairly tickles the hand of a good mechanic. We've been making and perfecting this wrench for nearly 40 years— your guarantee of quality, materials and workmanship. Whether you’re a skilled mechanic, radio fan, inventor, householder or handy man—you'll find daily uses for a TRIMO Pipe Wrench. Once a buyer, you'll never stop being a booster. TRIMONT MFG. CO. Roxbury, Mass. America’s leading wrench makers for nearly 40 years. Gemenerea RRB SULA A NRE TRIES —TRIMO IS) This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33 Made in Eight Sizes

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an a aaa Remington, — RaSe eR R7483 Generat Utiniry Knire. A blade for every purpose. Large spear blade for - heavy work. Small clip blade. Pen blade. Stag handle. Nickel Silver bolsters, lining, and shield. Length, closed, 334 inches. Trust the Name Remington— the Hallmark of Good Steel Remington knife. Established 1816 25 Broadway — rena You will appreciate the practical advan-_ tages of Remington knives designed ex- @@ pressly to meet the exacting require- 2 ments of the carpenter and skilled me- chanic. Add one of these useful Reming- tons to your kit. Here are two practical patterns illustrated. Others in various combinations of blades and handles may be seen at your dealer’s. If he hasn’t them he will gladly order them for you. Send for a circular describing Remington carpenter’s and mechanic’s knives. Remington Arms Company, Inc. rs} POPULAR SCIENCE MONTHLY ; ; ‘ll $ ~ OU can’t tell whether a knife blade * Ce 7 is made of good steel by looking at it, feeling it, or blowing your breath on it. But if you could tell quality in one of Ff f these ways, you would always buy a Yt For over a century Remington has been developing scientific, thorough, and ex- act heat-treatments for steel. Reming- ton’s methods of forging, hardening, and tempering insure blades with the re- markably keen, durable, and uniform cutting edges which are a distinguishing feature of all Remington pocket cutlery. CARPENTER'S KNIFE. Large, heavy spear blade. Sheepfoot blade for scrib- ing and coping. Pen blade. Stag handle. Nickel Silver bolsters and shield. Brass lining. Length, closed, 314 inches, New York City — Remington es Rifles Ammunition Shotguns Game Loads Cutlery Cash Registers March, 1925 "THE welding torch or blowpipe, when Home Workshop Chemistry Simple Fo mulas that Will Save Time and Money :——— = c used with both acetylene and oxygen gas, gives a temperature of 787° p Such a temperature cannot be attained | in the home workshop, but a heat of ap proximately 5000° F. is within the reach of any one for such purposes as welding iron to iron. The process em- ployed is known as thermite welding. In spite of the ter- rific heat used, the method is Fcuring the ferric oxide and alu- minum powder into the crucible (above) and add- ing the magne- sium and potas- sium permanga- nate (at left) safe if a reasonable caution is observed. Thoroughly mix ferric oxide and alu- minum powder, using about equal quan- tities of each; a slight excess of aluminum powder is an advantage. Place this mix- ture in a conical container, such as an old tin funnel or crucible with the bottom hole covered with a piece of heavy paper. At the top of the powder spread about a half teaspoon of powdered magnesium. This is topped with a level teaspoon of potassium permanganate heaped in the center. Make a depression in this heap. Fill a box with sand and on the sand place the iron to be welded. Make a form of the sand to surround the joint Just above | on all sides except the top. Dropping glycerine into the potassium per- manganate to set off the welding mixture the mold, place the thermite mixture, held by means of a wire tripod. | Place from 4 to 6 drops of glycerine quickly in the depression of the potat sium permanganate and stand away. A stream of white-hot molten iron soon run into the mold and form a weld. Large pieces should be preheated to redness. © This scal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 73. ee US! sin ha ch put to to dif too

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rch, 1995 shop y iS that Time Money cece 'y when oxygen 78° FB, ttained | ; Of ap- e reach welding z the ferric and alu- powder e crucible ) and add- e€ magne- ind potas- permanga- (at left) bserved. and alu- al quan- uminum shis mix- as an old bottom ry paper. ad about spoon of d in the his heap. the sand Make a the joint ist. above | March, 1925 EVERY home has its “Handy Man.” Per- haps it’s the man of the house; Grandpa; Junior; or maybe it’s Mother herself who is called upon to do those little repair jobs around the house. They seem to pop up every day. Each night when father gets home _ there is some minor pe thing to be done. The front door may need re- hanging or the hinges tightened. There’s a call for a good sturdy screw driver—and perhaps a keen- edged chisel. It doesn’t take long when you get at it~and our Handy Man takes real pleasure in doing ; it if he has good tools to work with. How about fixing a drain for the refrigera- tor? That’s something for which Mother has been asking for months. A good brace—like the Pexto Samson and a sharp bit—and it’s done in ten minutes. Then isn’t Mother pleased! A new lighting fixture — the cord to the elec- ' Exp. Bit No. 100 tures—friend Handy Man is going to need some good pliers to make those jobs easy. And then those little emergency. plumbing jobs— the trap to the sink—and such like—no plumber for a little job like that; a dependable pipe wrench and the Handy Man has earned his title again. One other tool he is going to want—a a monkey wrench — really || x indispensable. Renewing 1) eee washers on the faucets and a hundred other. uses. Then again home simply isn’t without a hammer. Perhaps it’s chair-tips or slides to put on — curtain fixtures to put up—a_ crate to open. There’s a big difference in hammers, too. A good one lasts POPULAR SCIENCE MONTHLY To the Handy Man in Your Home--- . done with good tools. tric iron — hanging pic-! © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. so much longer nothing else will do. A bit of sheet metal to cut and nail above the hot-water heater; it would ruin Mother’s shears te cut it with them — and Dad’s hands would get pretty sore, too. But a pair of Pexto § Snips will make an easy job of it. They’re built for just that work. In- No. 100 clude them in the list. ' And so the story goes; endless little jobs easily A source of real pleasure to do these little things yourself, aside from the actual money § savings. How proud Mother is that you can do them— the enjoyment you get from it may make it a real hobby—and an eco- nomical one too. ~ No more. borrowing from Jones or Smith — as these jobs come up. Start a little Tool-Kit of your own. And just a hint—you can’t go wrong on Pexto Tools. Ask your dealer—and look for the Pexto Oval shown below. It is your assurance of get- ting Worth-While Tools. | Booklets important lines are avail- covering our 0 - able for free distribution. No. 1819 Original Pexto Tools are carried by practically all progressive dealers everywhere, CEXTO WORTH-WHILE TOOLS The Peck, Stow & Wilcox Company — Southington, Connecticut, U.S. A.

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POPULAR SCIENCE MONTHLY Give us Telephones Following the war, when business and social life surged again into normal channels, there came the cry from homes, hospitals, schools, mills, offices—“Give us telephones.” No one in the telephone company will ever forget those days. Doctors, nurses and those who were sick had to be given telephones first. New buildings, delayed by war emergency, had to be constructed, switchboards built and installed, cables made and laid, lines run and telephones attached. - The telephone shortage is never far away. If for a few years the telephone company was unable to build ahead, if it neglected to push into the markets for capital and materials for the future’s need, there would be a recurrence of the dearth of telephones. No one could dread that eventuality so much as the 350,000 telephone workers. Bell System engineers measure and forecast the growth of communities; cables, conduits, switchboards and_ buildings _are: planned and developed years ahead of the need, that facilities may be provided in advance of telephone want. Population or business requirements added to a community must find the telephone ready, waiting. AMERICAN TELEPHONE AND TELEGRAPHICOMPANY AND ASSOCIATED COMPANIES BELL SYSTEM One Policy, One System, Universal Service $25.00 in PRIZE Let Boice Help You Build It! - No matter what you want to build. Boice can help you. B u y He’ll send you the Now Boice-Crane Junior Saw ; or any other Boice-Crane machine on monthly payments. He gives you unsurpass: prices and values with a positive money-back guar- Machine shown will saw, See top page 8 infront of book for details economical. Saws Sold with or without motor. Sor _ Descriptive Saws, Drills, Saws and the Boice E-Z-Pay Plan. W.B.& J.E. BOICE er P. S.13-A, Toledo, Ohio = ld’. lake 3 ‘orld’s camper Makers of Smali March, 1995 (Continued from page 97) are 1g in. wide and 3/64. in. thick, for these need to be the strongest. The mid. dle ones are 14 by 1/82 in., andthe two short ones, 3/32 by 1/32 in. 3a To fasten the braces to the beams force their ends completely through the slits so that they extend on the other side | (No. 1, Fig. 2). Before gluing and, binding | them, however, the frame should be. trued up so that the beams are straight, To do this, slide the braces one way or the iy \e CROSS PIECE ~~ FORCED THROUGH SLITTING : THE BEAM a RUBBER y¥ HOOKS Va ” a /2 DIA. ° ve ae OY J" cuiDES FOR Fru BBER BAND: i } © WIRE OR NAIL PROPELLER —~ GLOSSY od SIDE HANGER BAMBOO RIG GLOSSY WEY » © = SING BEAMS AND BAMBOO RIBS i WING-BEAM SPLICE ————— ———1 RUBBER BAND FOR FASTENING WING © TO MAIN BEAM 37, DIHEDRAL / sary © ip ee es SS FRONT walt g ELEVATOR Fig. 2. Connecting cross pieces to beams, making wire fittings, and other details © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. | truding parts flush with the beam. The | be bound at their intersection. | other in the slits. Then glue and bind, and | after the glue has hardened, cut the pro- braces that cross each other also should In the drawings three wire fittings, which look like hooks, are along each side of the frame. These are guides for the rubber bands (No. 3, Fig. 2). They are very important, for they serve to strengthen and keep the frame more rigid when it is subject to the heavy stress from the strong rubbers. These guides (Continued on page 130)

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2 6 S YOU KNOW WHAT TO EXPECT af Dp YOU BUY a box of candy made by a reputable manufacturer you know exactly what you are going to get. There is no guesswork, no uncertainty, no gamble in candy that is made on a wholesale basis. The quality must always be the same. The difference of two degrees in boiling a 200-pound batch of candy will ruin the whole batch. But modern candy-manufacturers assure themselves against loss and insure uniform results by using Zyeos Heat Indicating, Recording and Controlling Instruments—the Sixth Sense of Industry. And by using Taylor’s Home Candy Maker’s Ther- mometer, you can make candy at home of the same uni- form quality obtained. by the manufacturers in making millions of pounds of candy. Whether you are in the business of making candy or steel, canning fruits and vegetables, or baking bread, if your manufacturing processes include heat treatment there are Zveos Heat Indicating, Recording or Controlling Instru- ments that will help you get the uniform results that are absolutely essential to production on a volume basis. MANUFACTURERS If your manufacturing problems require the indicating, recording or controlling of heat, there is a type and style of instrument in the Jos Line of 8000 varieties that will help you. Informative literature on any type of instrument will be sent you promptly on request, or our engineer will consult with you on the application of Jeos to your particular manufacturing problem. Taylor /nstrument Companies Main Office and Factory ROCHESTER, N. Y. U.S.A. POPULAR SCIENCE MONTHLY Canadian Plant: Zycos BUILDING, TORONTO Zycos Office Thermometers An aid in promoting human efficiency. Zycos Bath Thermometers To enable you to get the most good from your bath. Zycos Home Set BakeOvenThermom- eter, CandyThermom- eter, Sugar Meter. The secret of accurate res- ults in cooking. Dycos Wall Thermometers To help you maintain a temperature in your house conductive to good health. Tycos Quality Compasses To show you the right way in unfamiliar country. Zycos Fever Thermometers A necessity in every home. Tycos Stormoguide Forecasts the weather twenty-four hours ahead with depend- able accuracy. Tycos Hygrometer To enable youtokeep the humidity of the atmosphere in your home correct at all times. Your dealer will show them to you. Ask us, on a postal, for booklets on any of the above. COS ~ Ly | For the, Protessiote ' Zcos Sphygmomanameter, Pocket and Office type Zycos Urinalysis Glassware. u a” Zycos Fever Thermometers. Bulletins on request. © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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130

Federal Factory Facts

Tip and sleeve are accurately machined to 250/1000ths. of- an inch insuring accuracy of fit. in jack.

Seats with set screws to receive tip or spade of phone cords insure @ positive contact.

Tip and sleeve are given a 300 volt breakdown test. Every plug must pass this test to qualify.

POPULAR SCIENCE MONTHLY

Moulded bakelite shell of two pieces totally en -closing terminals and affording pperator a: firm, yet convenient, grip.

Nut for screw insert cannot be lost when plug is taken apart.

Loop to relieve connection terminals of strain.

Drawing shows interior view of plug with one half of shell re- moved.

6 Ge plug is the key that un- locks the full possibilities of your receiver. No matter what you are getting off the air, you hear only what the plug lets through. Buy a No. 15 Federal Plug for your radio phones or loud speaker

if you want to know what your radio set can give you. Buy a Federal Plug today—also take advantage of the other 130 standard radio parts sold under the same Federal iron-clad per- formance guarantee. FEDERAL TELEPHONE MANUFACTURING CORP. Buffalo, N. Y. © Boston Chicago New York San Francisco Philadelphia - ; Bridgeburg Pittsburgh Canada

Ole Evinrude’s New (15) Quick Detachable Rowboat Motor @

Weighs less than 17 Ibs. per H. P, Easily car- ried with you anywhere you go. Fastensina ffy to any boat and away you go. No row- ng, no work, no bother, Just ride and enjoy the est of water sports. Slow down for fis . Speed up for racing. Write for FREE Catalog — 12 exclusive features, especially le Evinrude’s latest i See Ween Oe eventicn. ELTO OUTBOARD MOTOR CO., Dept. w Manufacturers’ Home Bidg., Milwaukee, Wis. ctto

“The Motor that Starts with a Touch

justed tempera’ wn hg eos. 26 eer aas Strata , in 100 d 3 B nce in small monthly ad ., Watch Burlington Company Oth Street and Marsha Dept. 43-63" Chicago, illinois Tests Show Ford . Can Run 60 Miles on Gallon of Gas

The amazing fact that a Ford can run 60 miles on a gallon of gasoline was recently tests conducted by brought to light thru America’s foremost en- gineers. Great strides have already been made in this direction by the recent invention of a simple attachment which can be installed in a few minutes with- out any alterations to motor. <A. C. Winter- burn made 41.4 miles on 1 gallon of gasoline after this device was attached. B.O. Weeks, famous aviator and in- ventor, wants agents and will send sample for trial. Write him today at 426-762 Eleventh St., Milwaukee, Wis. tS] This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

Easily Built Model Plane (Continued from page 128) should be 14 in. in diameter. The Part that lies next the beam should be bent in a U shape so that the guide can be bound securely to the beam. On each beam at the rear is a wire pro. peller hanger (No. 4, Fig. 2). This, too should be bent in a U shape where it lies along the beam. Particular care shoylq be exercised in binding it firmly to the beams because it must hold the direct pylj of the rubber. If one has a steel drill, nail hangers which are somewhat stronger than the wire, may be substituted. The najj hanger may be made by drilling a hole 1/32 in. in diameter through the flattened ewes F BLOCK PENCIL BLANK FIRST — HALF ROUGH CUT FINISHED FINISH SEVEN STAGES IN PROPELLER CONSTRUCTION ZZ G ip

COMPLETED LEFT HAND RIGHT HAND

MAIN BEAM_WUA (2) PROPELLER iit Fig. 3. Steps in whittling the airplane propellers, the propeller shafts, hanger, and wire holder for balancing propellers head of a 1-in. brad. The part that lies along the beam also should be flattened to insure a solid fit against the beam. For those who have scales, the frame should weigh about an ounce. The wings are built of two pine beams with bamboo ribs and wing tips. The beams are 3/16 in. wide, 1 in. thick, and 29 in. long, rounded on the under side to lessen air resistance (No. 5, Fig. 2). As will be noticed in the sketches, the wing has a dihedral angle, that is, the beams bend upward at the center. In this case the upward bend amounts to 1 in. (Fig. 1). To obtain this dihedral angle, splice the beams, as in No. 6, Fig. 2, or bend them carefully over a candle flame (No. 6), holding them about 1 in. above the flame. If the wood should be cracked or scarred in bending, be sure to reinforce the weakened place by gluing and binding a piece of bamboo over it. : The ribs are made of bamboo, 1/16 in. wide and 3/64 in. thick, spaced 5% in apart. They should be bound to the beams after the dihedral angle has been made. The glossy part of the bamboo (Continued on page 132) WIRE HOLDER FOR a PROPELLERS,

\

———et

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h, 1925 7 nt in ound @ pro- y too, it lieg hould (0 the ct pull ngers, in the > hail a hole ttened ND INGER ; lane nger, llers that lies tened to 1. .e frame ie beams ys. The ick, and r side to , 2). ae the wing 1e beams this case (Fig. 1). splice the nd them (No. 6), he flame. r scarred orce the yinding @ , 1/16 in. 1 5% in. 1 to the has been bamboo —$—$—$—— POPULAR SCIENCE MONTHLY “That’s all I need to know— It’s a Maydole Hammer!” OOK for the name “D. Maydole’” stamped on the head. It’s absolute assurance that the de- sign, material and workmanship in that particular hammer is as near perfection as human skill, plus over 80 years of experience, can make it. Ask any old-timer—he’ll tell you there’s “hang” in a Maydole Hammer that’s lacking in hammers less carefully made: There’s years and years of service in the press-forged steel heads: There’s a grip in the claws of a Maydole that never lets go: There’s a satisfaction in knowing that when you put a May- dole in your kit you’ve settled all your hammer troubles for a long time to come. In 1843, David Maydole—the founder of the business —said: “I make the best hammer,” and from that day to this, we have striven to hold the standard set. If you are a hammer user send for our free pocket handbook 23B—it’s worth a lot to a carpenter or anyone who uses hammers. THE DAVID MAYDOLE HAMMER CO. Norwich New York 7610 @ This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. re ee é

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POPULAR SCIENCE MONTHLY 21 Perfect Jewels Adjusted to Positions Adjusted to Tempera- ture Adjusted tolIsochronism Adjusted to the Second 25-Year Case Gold Strata We will send this famous watch, express prepaid, for you to examine, to inspect, to admire, to approve, without one penny advance payment. Examine the watch and be convinced it’s the best watch buy you ever saw. Just a small payment down, the balance in easy MONTHLY payments. You use the watch while paying for it. Save Y% to Y% of Your Money By purchasing this Famous Santa Fe Special Watch. Not only are you saving money from the present day prices of watches, but you can still secure the ‘“‘Santa Fe Special’’ Watch at the same low prices and terms that have made our watches famous. Ladies’ Wrist Watches This Artistic dependable Lady’s Wrist Watch, fitted with genuine Illinois Spring- field movements. A perfect timepiece. Beautiful 14-Karat white or green SOLID GOLD cases. Ask for New Watch Book showing Cases in all the new shapes and designs. . Watch sent on approval and sold on payments. Send for Free Watch Book Clip the coupon, fill out and receive the FREE WATCH BOOK. All the newest watch case designs in white or green gold, fancy shapes and thin models are shown. Read our easy payment offer. Wear the watch 30 days FREE. Watch sent for your examination and approval without a penny down. Nothing to risk. See the watch before you buy. Write for FREE Book Today Select Your Watch—Mail Coupon. SANTA FE WATCH COMPANY 380 Thomas Building, TOPEKA, KAN. The Home of the Great Santa Fe Railway Santa Fe Watch Co., 380 Thomas Building, Topeka, Kan. Please send prepaid and without obligation your Watch Book Free, explaining your ‘‘Ne Money Down” Offer #n the Santa Fe Special Watch. and eee should be on top, as in No. 5, Fig. 2. The bamboo wing tips should be curved over a candle flame. In order to have both wing tips of exactly the same shape, use a wide piece of bamboo in bend- ing, and split it into two pieces after the shape has been obtained. Trim down the tips until they are 1/16 in. wide and 3/64 in. thick. The tips extend 2 in. beyond the ends of the beams. At the end of each wing beam cut out a small piece of wood. Fit the end of the wing tip in place of this piece; glue and bind (No. 7, Fig. 2). ‘[ Se wing is covered on top with tissue paper attached to the beams with banana oil. Glue, although heavier, may be substituted for the oil. First, take a piece of paper large enough to overlap 1 in. on the edges. Apply banana oil to the middle rib and lay the paper on it immediately. Allow this to become thoroughly dry and fast before attempt- ing to proceed with the covering. Now, apply the oil to the beams, section by section, between the ribs, and then stick the paper to them. Before the banana oil has evaporated, work out the wrinkles in the paper. When doing this, keep the paper flat against the beams. After the paper has been attached to the entire framework of the wing, trim off the overlap along the edges by sandpaper- ing. The wing completed should weigh about 1% oz. The elevator, as the small front wing is called, is constructed like the main wing, the only difference being in the main beams and the dihedral angles (No. 10, Fig. 2). The main beams of the elevator are of bamboo, 1/16 in. wide, 1/32 in. thick, and 8 in. long, placed with the glossy part on the under side. The ele- vator tips extend 2 in. beyond the end of the main beams, thus making the over-all length 12 in. They are 1/16 in. wide and 1/16 in. thick, and the ribs 1/16 in. wide and 1/32 in. thick. HE dihedral angle, amounting to 34 in. between the ribs, should be placed only in the front beam. This should be done after the framework of the elevator has been completed. The dihedral angle here is very important because a good flight is hardly possible without it. The elevator, which is papered in ex- actly the same manner as the wing, should weigh no more than 1/10 oz. The propellers are carved out of solid blocks of wood, 5g by 114 by 12 in. (A, Fig. 3). Draw diagonal lines from the opposite corners on the wide sides of the blocks (B, Fig. 3). Then with a knife cut along these lines to make the propeller blank @C). Before actual carving is begun, it is advisable to force a hole for the pro- peller shaft through the hub of the blank. This may be done by working through a straight piece of wire or by drilling. Start cutting as shown at D, Fig. 3. The upper side of each blade should be (Continued from page 130) flat or slightly cambered. It should be finished, except for fine sandpapering, be. fore the carving on the under side ig be! gun (E£). After the final thickness of the blades has been obtained (F), the tips can be rounded to a more graceful shape (G). Then finish off the propellers with fing sandpaper. One propeller should be left-handed and the other right-handed. This is neges, sary because the propellers must revolye in opposite directions on the model to keep it stable in flight. A WIRE propeller shaft should be thrust through the hole in the hub of each | propeller. Slip a few washers over the| protruding end, then end the wire, as in| No. 11, Fig. 3, and force it into the wood, The shafts extend from the under side of the propellers in this case because the pro- pellers are pushers. To balance a propeller, make a small wire holder, as in No. 13, Fig. 3, which will allow the propeller to revolve freely, Slip the shaft in this holder. The heavier blade will hang downward. Sandpaper until the blades balance. The total weight of the propellers should be about 1/3 oz. To assemble the model, fasten on the wing and elevator by rubber bands, ag indicated at No. 9, Fig. 2. Be sure that the front edge of the elevator is toward the nose (Fig. 1). Attach the propellers, as in No. 12, Fig. 3. The power plant is furnished by 10 strands of 1-in. flat rubber attached to each propeller. The rubber should bé strung so as to have a sag of two inches, If one cannot secure 1¥-in. flat rubber, six strands of 3/16-in. flat rubber on each pro peller will serve equally well. Square rubber may be used, but it is not the best. In flying this model, remember that it is a pusher type, and, unlike large air planes, the small wing is in the front) The initial flights should be attempted on a fairly calm day. Wind each prope 100 times. Launch the model with 4 gentle thrust slightly upward. 1° NOT be discouraged if it does fly well at first, the trouble is pr ably in the adjustment. If on the flight the model tends to point down it has insufficient elevation. To rem this move both the wing and elevator fraction of an inch forward. If, on the other hand, the model should tend to climb too rapidly and stall, move the wing am elevator backward slightly. : After one has obtained steady flights with the model, the rubber may be wound up until it has a double row of knots. one has a winder for winding the rubber, better results will be secured. H Under fair weather conditions the model should remain in the air for about 100 seconds and fly several hundred feet. . you become more experienced, you Wi soon learn to adjust this model so thatl flies at its best. ‘a — ae © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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POPULAR SCIENCE MONTHLY DE FOREST leads again Another jump ahead! Just out—first in 1925 DE FOREST’S greatest triumph. A truly remarkable advance in ease of operation—beauty of tone —selectivity—distance range. It uses tube detector instead of crystal. You should see and test this in- strument before you buy any set. Its refinements and improvements are too many to tell here. Ask your nearest De Forest dealer to bring it to your home and show you how simply and perfectly it operates. It will be hard for you to let him take it away. Price Range $125 to $200 > about on the nds, ag ire that toward »pellers, | by 10 .ched to ould » inches, bber, six ach pro he rubber, ‘the modd ee s = eg about 1 REG. U.S. PAT. OFF, — Made by De Forest Radio Company, Jersey City 1 so that } —$—$— G This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. 33.

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POPULAR SCIENCE MONTHLY pees HIGH SCHOOL COURSE IN Two YEARS YOU{ARE BADLY if you lack § HA MDICAPPED HizhSchool training. You cgnnot attain business or social prominence. You are barred from a successful business career, from the leading professions, from well- paid cjvil service jobs, from teaching and college entrance. In fact, em- ployers of practically all worth-while positions demand High School train- ing. You can’t hope to succeed in the face of this handicap. But you can remove it. Let the American School help you. FIT YOURSELF FOR A BIG FUTURE Thiscourse, which has been prepared by some of America’s leading professors, will broaden your mind, and make you keen, alert and capable. It is com- plete, simplified and up-to-date. It covers all subjects given in a resident school and meets all requirements of a High School training. From the first lesson to the last you are care- fully examined and coached, USE SPARE TIMEONLY Most people édle away fifty hours a week. Probably you do. Use only one-fifth of your wasted hours for study and you can remove your present handicap within two years. You will enjoy the lessons and the knowledge you will gain will well repay the time spent in study. Check and mail the coupon NOW for full particulars and Free Bulletin, American School Dept. H-375: Drexel Ave. and S8th $?., Chicago American School Dept. H-375 Drexel Ave. & 58th St., Chicago Send me full information on the subject checked and how you will help me win success, welt Architect Law ......Building Contractor sonal Automobile Engineer mien Automobile Repairman +». Civil Engineer dunneil Structural Engineer eseoad Business Manager pie Cert. Public Accountant ......&ccountant and Auditor -»..-- Bookkee per cose a and Designer elie ectrica] Engineer enseel Elocris Light & Power ..-...General Education o-.--- Vocational Guidance Name — AdAes., HE owner of a small carpenter-con- tractor shop in a Mid-Western state installed power for his machine tools by utilizing an old but sound auto engine. The engine was overhauled and then mounted on two concrete standards capped with channel iron. Being of the heavy, flat-faced type, the flywheel is belted directly to a line-shaft pulley overhead. The throttle is regu- lated from the left side, a heavy wire and ratchet serving to hold it in any desired position. The spark is adjusted in the same general way, but held with a bolt. The outfit develops 11 hp. at 1200 r. p.m. The water-cooling system is simple, yet rather unique. The circulation pump is connected by pipes with the outside cooler illustrated in the smaller of the accompanying photos. The hot water finds an outlet in a series of small, closely spaced holes drilled in the upper hori- zontal pipe. To this pipe a section of l4-in. mesh-wire screen is soldered. A Old Auto Engine Auto engine set up as stationary power plant, and outside water. cooling system: with screen over which wa- ter runs in fine streams trough of sheet iron at the bottom eol- lects the cooled water, which is drawn back into the engine by the return pipe, HIS teeter-totter will appeal to any boy or girl. It is sturdy, accident- proof, and comfortable. The materials required are: 1 plank 2 in. thick, 18 ft. long 1 broom handle 1 3-ft. length of 4 by 6 in. wood 1 6-ft. length of 4 by 4 in. wood 1 10-ft. length of 1 by 4 in. wood 1 2-ft. length of cedar post, 6 in. in diameter Spikes in three sizes The __teeter- totter ready for use and view of the central sup- ports, which are A-shaped The plank is shaped at each end with a draw-knife. The round post is smoothed up and cut in half. One end of each part is reduced to 2 in. in diameter for a dis- tance of 2 in. These round tenons are driven into 2-in. holes bored through the center of the plank ends 20 in. from the ends. A hardwood wedge is driven into each tenon from the under side and the How to Build a Strong Teeter-Totter pieces also are toe-nailed for greater security. Sections of broom handle are set through the uprights to serve as grips, The support is built up of 4 by 4 in, legs, which rest in pairs, like A’s, upon two bed pieces of the same material. The bearings are cut from 4 by 6 in. pieces, The axle or pivot is a piece of 4 by 4 nailed to the under side of the plank at the exact center with the protruding ends made perfectly round and saturated with grease. Notches in the 4 by 6 in. pieces form the bearings; these also should be as smooth as possible and well greased. The plank wood should be without knots or flaws of any kind and straight- grained so that it will not warp. Test it for balance and if one end is heavier than the other, hew that end down until the balance is perfect. Give all parts a thin priming coat, and two coats of good paint, or finish it with spar varnish, —D. V. H. A Rollicking Crib for Baty HIS spring- suspended baby crib or swing is sup- ported by two rectangles of heavy wire, one 12 by 16 in. and the other 18 by 30 in., held to- gether by strips of canvas folded and sewed for strength. The bottom portion or crib proper is of 20-02. sewed to form a compartment about 8 deep. The iron ring at the top is fas to a spiral spring hanging from the pore ceiling. The mosquito-netting cover ® made of four triangular-shaped pieces. ‘(S] This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. 7 b c

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om col- s drawn im pipe, r greater ndle are as grips. by 4 in. .’8, upon rial. The 1. pieces, f 4 by 4 plank at ding ends ated with in. pieces yuld be as sed. without straight- . Test it vier than until the rts a thin of good - varnish. Baby

POPULAR SCIENCE MONTHLY 135 OT Way Repair Punctures © VULCANIZE FIRST lehate mp aate @.a2 IT LAST

LIGHT THE FUEL Get Your Vulcanizer Now— | you may need it this week A Packard is no better than a Ford when it comes to punctures. ) That’s liable to happen to anybody. But you can be prepared for such emergencies, the same as nearly three million motorists who always carry Shaler Vulcanizers in their cars. They want to be prepared to make a quick, permanent repair when they get stuck on the road. One such experience more than offsets the small cost of the vulcanizer, and is the most convincing evidence of its conven- ience and dependability. Complete Outfit Costs Only $1.50 Slightly higher in Canada and far West. Get yours today at any accessory dealer, garage or hardware store. They all carry the Shaler in stock. C. A. SHALER CO. Executive Offices and Factory: 2100 Fourth Street, Waupun, Wisconsin Branch Factories: Beeston, England, and Montreal, Canada S HALE wea. 5 MINUTE VULCANIZER e ' 4, =< SN - { e NS z= We ¢ Why the Shaler Is Quicker and Easier The Shaler Patch-&-Heat Unit is the secret. It is a little tin pan witha piece of raw rubber on the bottom and containing a disc of prepared solid fuel that gives just the right amount of heat to cure the patch. To mend a puncture you clamp one of these Units over it, touch a match to the fuel, and wait 5 minutes. That’s all there is to it. No gasoline,no shears no knife to cut a patch to fit—not even cement—needed to make a heat-vul- canized repair anywhere on the road. There is no substitute for the Shaler because there is no substitute for Vul- canizing with Heat. Any repair man will tell you that.

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

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POPULAR SCIENCE MONTHLY

quipped with ADIO receiving sets e A L A E HE 1}4-volt tubes may be supplied With A-battery current from flashlight cal, F Your Own that have become too weak for thei

— original purpose, but still retain e Easy Payment Pian a These discarded cells usually may be had for the ask from a friendly dealer, In — conneetj these cells in paral. , lel, I place them 4 in a small box of vy three-ply veneer 4 A by 23% by 1% in, 4 The hinged lid jg on This 16”x6’ Quick Change Gear South Bend ¢ ,_ a ae : Screw Cutting Approved by Popular Science Institute of Standards L A T H E E: fitted inside with a yin. strip of Only $466 Complete—orner Lathes as Low as $197 on Terms “ee pig spring brass 4 in, Our easy-payment plan enables vou to use y South i “~ 1 se your South Bend Lathe while : Ve , you are paying for it. You make a payment down, and the Lathe is shipped at once on per gare eg —_— 2 “hi beyond the | 30 days’ trial. Convenient monthly payments may be arranged for the balance. In this Pes te Pucagceate: | way the Lathe helps earn its own cost, and you secure the same high quality product used similar strip on the bottom of the bor | in America’s leading shops. serves as the negative contact piece, Small binding posts are soldered to the 32 Major Improvements—tncreased Accuracy and Efficiency | 14-in. extensions so that the battery can The New South Bend Lathes embody 32 major improvements made in the be connected easily and quickly sim last two years—all insuring extreme accuracy, efficiency, economy and convenience. set.—GEORGE DEAN, Bloomington, Ind. More than 31,000 South Bend Lathes in use. Slabs of Bark Decorate Porch- sourt | BEND LATHE WORKS, i ut CATALOG FREE! 3 Rail Flower Boxes

317 East Madison St., South Bend, Ind. Gentlemen: Showing 96 Styles—All Sizes I would like your factory price and terms é Let us send you a copy of this Free Book. Then Pieies ttimama Lathe. & you can select just the Lathe you need. Compare : B our money-saving prices and liberal terms with PUN « - oewe cc ccccccrenerceaccsecscens B what others offer. Write or send coupon today. ee eee bs 17 EA i aie y South Bend Lathe Works, Sciri'senp, Ino. us. 4

: PRICES REDUCED O CONCEAL the _ bareness and} <a rp crudity of plain wooden poreh-rail Only = Und ery, —— flower boxes, one home-owner cut slabs Mis of bark from a fallen cottonwood tree and

attached them to the boxes with shingle nails. In the fall, when the plants are taken indoors for the winter, the box wil be emptied and stored in the basement until the following spring.—LOUREE 0s BORN, Lincoln, Neb.

Paper Forms Wind Break and Spark Screen for Pipe EN who smoke

Yes, ) 1 st prices on SNDERWOOD, REMINGTON, L.C. SMITH, ROYAL, and all standard makes on easiest terms ever a pipe out of eat. ae new by the 140-page Book full of life- dnoen Gail that ehean size ruled forms, each one the wind blows hard

10 Days’ Trial—5 Years Guarantee Our liberal ‘‘direct from factory plan’’ saves half. You actually use the typewriter 10 days without obligation to buy. Let us prove we have the great- est typewriter bargains ever offered. Big saving. Big Ulustrated Catalog Free This interesting valuable book explains fully how “Young Process of Re-Manufacturing’’ guarantees you highest quality,perfect service and satisfaction. YOUNG TYPEWRITER CO. Est. 1911 a mts a completely filled in. The an- swer to problems of account- the tobacco burns ing and record keeping for out quickly or any business or profession. causes dangerous Send forthis FREE Book today sparks. Pipe caps John C. Moore Corporation fj [are not always (Established 1839) handy, but a simple rf.“ Send Coupon Now = === 2189 Stone St., Rochester, N. Y. wind protector can be made from a scrap of paper wrapped VP sornetzzertterco-Dat" | FERRI, eer Send me ~te “eet and Special / LOOSE LEAF about the bowl two or three times and Lake MOORE ’ SYSTEMS. twisted into a quill, as illustrated. reas UBC) eee | wire lead (in oil) mixed with whiting 300,000 Offices — which is a powder, makes a putty that State dries hard and sticks fast. eo

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

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eh iy | POPULAR SCIENCE MONTHLY shop S Serve pec With " lied with EVEREADY HOUR There’s more life in eh cl raat ae ajc tense fi | Foveready Batteries AL enough “Eveready Group.” Broadcast through all tubes, stations WEAF NewYork WF Philadelphia Buy Eveready “B” Batteries and you get elec- S usually J we " eo oS tricity in its surest, safest and most compact form. meen = They reduce your operating expense. New de- mnecting ee velopments in the Union Carbide and Carbon Re- sin paral : aaa HntR search Laboratories, Inc., have been converted : Hi Sees ; into new manufacturing processes in the Ever- eady factories. Good as they always have been, Eveready “B” Batteries are much better today. The Eveready achievement of giving you more hours of' “B” Battery service for less money has cut the cost of running receivers in half, and in some cases the new Evereadys make “‘B”’ Battery expense only a third of what it used to be. } There is an Eveready Radio Battery for every : me ; radio use. of the box Seegaee pene M 1 and dl et Piece, : : Manufactured and guaranteed by 2d to the NATIONAL CARBON COMPANY, Inc. ery can with the New York San Francisco on, Ind, Canadian National Carbon Co., Limited, Toronto, Ontario is | EVEREADY Radio Batteries WIJAR_ Providence : t e asl WEEI_ Boston WG or, : Headquarters for Radio Battery Information Dry Cell “4” eo ade! Battery y on IS) for all io = ary cell m tubes No nt —they last longer " A i AASAA! 1y 4% ihe Ace ek Ai ‘ kas Ne ¥ ‘9 We i\ a i : eam 1 No. 771. Sphemanee i = gfe | 41,-volt + wrappa a SS ee times and peeeiiie seieeette ereeeenreceEeREEeY green —_ Sere ae eu UsruSEEESEEET: - See U See URIEEESEEEEEEEEEEY improves ted. a ea : 8 cult, fi it EEE EEEE EERE HERE REET saves “B” h whiting, 2 HEISEI: i Sie ie #3 SHEET TEESE Batteries putty that SE aacta Ssasteceeese ced jcasce¢eccaeececeetec sess eae cece ai Price 60¢ © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS, See page 33.

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POPULAR SCIENCE MONTHLY

i

q é €; a &: 2: 2 i § 3 4 3 E : ‘ 3 <

The World’s Wonder Set Manufactured and Guaranteed by EAGLE RADIO CO. The Famous Models A and B EAGLE NEUTRODYNE Eagle Radio Company 26 Boyden Place, Newark, N. J. EUTRODYNE\

at a Popular Price Makers of RECEIVERS Unprecedented demand ne- cessitates that all orders be filled in rotation.

$25.00 in PRIZE of book for details. See top of page 8 in front March, 1925

| |

orkshop] Small Ornamental Candelabra Turned from Wood F YOU have access to a wood-turn} lathe, you will find it easy to mua | candelabra shown in the accompanyin | illustrations. , The base, which is 51% in. in diameter is turned on the faceplate, and has a 3/.in. hole to take the upright. The standard ig turned from 4 piece 13% on. square. The four outside candle cups are turned as de- | tailed, and fast- ened to the stan- dard by means of brackets cut with | a coping-saw. The ends of the brack- | ets are made | slightly concave go as to fit closely at | a 1) \ a | yh ae —=is5 =e { Fy

YA. SQUARES re 72 DIA

Ne DIA: WY The completed candelabra oe and details of candle cup 1. the joints and one small dowel is used in | each glued joint. | The hole for the center candle is 34 in. | in diameter; for the others, 11/16 in. If | five candles of the same size are used, the | four outer ones can be trimmed a little to | fit. It is possible to use a 34-in. bit for all | the holes if the four outer candle-holders are made a little heavier than shown. All the turned pieces are polished with | shellac in the lathe after a filler has been

Deafness jm Perfect hearing is now being re- stored in every condition of deaf- ness or defective hearing from causes such as Catarrhal Deaf- ness, Relaxed or Sunken Drums .. Thickened Drums, Roaring and Ss Hissing Sounds, Perforated a Wholly or Partially Destroy ee +2 Drums,Discharge from Ears, etc. Wilson Common-Sense Ear Drums “*Little Wireless Phones for the Ears?’ require no medicine but effectively replace what is lacking ot defective in thenatural eardrums, They are simple devices, which the wearer easily fits into the ears where they areinvisible. Soft, safe and comfortable. Write today for our 168 page FREE book on DEAF- giving you full particulars and testimonials. WILSON EAR_DRUM CO.., Incorvorated 736 Inter-Southern Bldg.’ LOUISVILLE, KY.

AGENTS «oon income Youcan sell PremierKnife Sharpeners to housewives, restaurants, stores, etc. 9 out of 10 will buy. Sells for

50c. Writetoday forattractive LARGE offer. PREMIER MFG. CO. PROFIT Dept. 9 Detroit, Mich. Sor you = OF pri C. IN YOUR HOME \_4 9 = -@ Our marvellous, = — per) practical MOVIE i. «= MACHINES sell as

low as $3.75 postpaid and use same size film.as big theatres. We also have wondertul films at lowest prices—witha_new film ex- change service. IN’T MISS THIS! Write NOW for free catalogue 'PARAMOUNT MFG. CO. Dept. PS7 Boston, Mass.

a | applied and allowed to dry. Felt is glued on the under side of the base.—E. E.

Surface Gage Made Cheaply from Auto-Engine Valve DISCARDED valve from a gf), Ford engine serves =f as the stand for the BINDING-POST homemade surface SCREW AND gage _ illustrated. The two nuts and screw used for ad- justing the gage wire are from a discarded dry cell, the cotter-pin hole in the stem being enlarged slightly in order to take the screw.— FRANK W. BENTLEY, JR.

A PIECE of garden hose split down one | side makes a good protector for a draw-

knife when it is to be placed in a chest or | drawer with other tools.—M. E. S.

Page 107

abra ining Ke the nying neter, 34-in, lard is four e cups as de- fast- stan- ins of , With . The brack- made ave so ely at bt — Zoo r

“Per Kee} sed in | 34 in. d, the ttle to for all olders | with ; been lued

> 2 the on one draw- est or

Radiola III-A. With four Radiotrons WD- 11, headphones, and Radiola Loudspeaker. Complete except batteries and antenna, $90. Radiola III. With two Radiotrons WD-11 and headphones. Agreat buyat . . $35. You Can always Add: Radiola Balanced (push pull) Amplifier, with two Radiotrons WD-11, to make a four tube set out of MOGI EIT, -«. « + « © * <i wee RADIO CORPORATION OF AMERICA Sales Offices: Suite No. 113 233 Broadway, New York 10 So. La Salle St., Chicago, Ill. 28 Geary St., San Francisco, Cal. Radiolas manufactured and distributed in Canada by the Canadian General Electric Company, Limited, Toronto, and the West- inghouse Company, Limited, Hamilton,Ont. POPULAR SCIENCE MONTHLY 139 Fun indoors ~ with a Radiola Good music, a glowing fire . . . comfort! Jokes, speeches, songs, dancing . . . fun! The best times of the winter, right at home, with a Radiola. Everywhere — city, suburb, and far-away farm — Radiola II]-a will bring in music and laughter— news and exciting new interests. It is low in cost —but big in performance, and with its four tubes it gets distance on dry batteries. It brings in pro- grams from the country over, brings them in always clear—always real! “There's a Radiola . for every purse”

This symbol of quality is your protection Radiola REG U.S. PAT OFF

Serre ees = = a — ————__—______— |

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

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S R os WILL NOT CILLATE CAREFULLY MATCHED ANO BAL STRUCTION FOR S TUB Ae J 2 ORILLING TEMPLATE FS yA SS NO NEUTRALITING OR ; oA n> a Don . se Ny NO Neutralizing OR Balancing Condensers Required when you build with this kit to produce a radio frequency receiver that will bring in even the most distant stations with the volume and clarity of locals. So selective that stations can settings. At your dealers, otherwise send purchase price and you will be supplied without further charge. Chas. Kit consists of 3 Masterpiece Tuned Radio Fre- quency Units carefully matched and balanced. Complete with wiring diagram and instructions for building any 5 tube tuned radio frequency re- ceiver and also drilling template for proper mounting, Each and every Freshman Masterpiece Coil bears a serial number and Trademark— our guarantee of electrical and mechanical perfection. the genuine. fresh Recetvers Anew Patls FRESHMAN BUILDING 240-248 WEST 40TH ST~NEW YORK.N-Y. ESHM MASTERPIECE It’s Easy to Build a five tube radio frequency receiver when you use the Freshman Masterpiece Kit SELF BALANCED LOW LOSS TUNED RADIO FREQUENCY KIT SH FASTERPIEG 3 MASTERPIECE TUNED RADIO FREQUENCY UNITS ANCED COMPLETE wit PNCED COMPLETE WITH WIRING DIAGRAM — ; a ie ; brought in day after day at the same dial A set that will be the equal, if not the superior, to any 5 tube receiver on the market, and what’s more, it’s extremely simple to operate. POPULAR SCIENCE MONTHLY A er a nn PROVIDED THIS TAG Lal x 1S NOT REMOVED. A SEE THAT SERIAL \o~ NUMBER IS ON EVERY BOX 50 B COMPLETE FREQUENCY RECEIVER ‘OR PROPER MOUNTING $ 17° For your protection demand only © man fo.Inc. AMBASSADOR Low Loss Products ciency of any set Satisfaction of the user. Low Loss Products have long been the choice of particular fans. and you will choose couipare them, them too. At all good dealers . Write for FREE circuit diagrams in which Ambassador products can be used. AMBASSADOR SALES COMPANY 108 Greenwich St. 426 W. Madison St., Chicago Master Tuning Coil Perfectly Balanced Head Phone Low Loss Condenser High grade, standard radio prod- ucts that will increase the effi- and add to the Ambassador See them— » New York AMAZINGELECTRICIRON Burns 821 HoursWith- out Getting Red Hot New York.—A new kind of Electric Iron just invented ends the possibilities of burned, scorched clothes and dangerous house fires. This new iron positively can’t start a fire— can’t burn clothes—and uses 1% less electricity. It has a safety Fuse that automatically turns the current off when the iron gets too hot and a warning glow that tells when the current is on or off, The new Electric Iron—called the Brite-Spot—sells quickly wherever shown and offers salesmen a rare opportunity to make big money in full or spare time. To interest men and women who desire to demonstrate the Brite-Spot in their own home town and in that way build up a business of their own, the manufacturers are making a Big Special Offer. Address The Diana Studios, Dept. 543, 334 Fifth Avenue, New York City. March, {995 | | | mounting a wooden pail on a pole and LY ® How to Build an Ornamentg} © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. Bird .House and Bath peat bring animation and life into a garden. They always can be at. tracted if provisions are made for their safety and comfort. The bird house illustrated is made by providing a roof. The platform projects Garden bird bath on wooden support and bird house for wrens made of an old pail 2 in. beyond the wall. Partitions for two or three compartments may be made, and this is desirable if it is expected to attract wrens. The reason is that a pair of wrens like to raise the second brood of the sea- son in a. new apartment. The bird bath consists of a pan cut from an old metal container and mounted ona EACH LEG MADE OF TWO |" BOARDS How simple it is to build the bird house and bath is indicated in these details wooden stand with legs of the shape illus- trated. For strength, each leg is com- posed of two thicknesses of 1-in. boards nailed together with the grain of one piece running at a slightly different angle from that of the other.—C. L. MELLER, Fargo, N. D. THE best methods of building an auto speedster will appear in the April issue. —

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ntal nto a > at- their le by - and jects and pail or two le, and attract wrens 1e sea- it from dona BEAD BOLT , 7 \ E OF 2S 10uUse etails pe illus- is com- boards of one it angle [ ELLER, an auto il issue. ee March, 1925 POPULAR SCIENCE MONTHLY A Special Offer! An opportunity for radio fans to save money in buying Celoron Panels and Vulcawood Cabinets E are making this special introductory offer to make new friends for our products and: for the dealers who sell them. Celoron is the standard insulating material among lead- ing radio manufacturers and it is the choice of nearly a million radio fans. It is made by the oldest and largest manufacturer of vulcanized fibre and laminated technical materials in the world. In spite of these facts there are many fans who never have had an opportunity to see and use this popular insulating material. Many others have never heard of the Vulcawood Cabinet—the new cabinet of bakelite. For a limited time, we offer you the privilege of buy- ‘ing these standard, well-known parts direct from our factory—at special introductory prices. Orders will be accepted subject to the conditions outlined below. This offer expires on April 30, 1925. Your money back if not satisfied If your dealer does not stock and carry these parts, you may select a cabinet, and the panel to fit it, at the special introductory prices quoted. In return for this privilege we ask you to send us your dealer’s name and the names of three of your friends who are radio fans. We shall refund your money without a whimper if you are not entirely satisfied with the goods when received. No red tape—no delay—no questions asked. This illustration shows the cabinet — with the panel in place. NEW VULCAWOOD CABINET the only bakelite cabinet made This new bakelite cabinet insulates your entire set. It protects your delicate instruments from dust and dirt. It eliminates troublesome body capacity effects. The Vulcawood Cabinet is grained and colored to match beautiful hand rubbed mahogany. It comes packed flat and is easy to set up. Vulcawood Cabinet Prices Sizes List Prices Special Prices 1)7x7x10 $7.95 $4.50 ao7 27 2i2 8 10 4.50 a7x7234 8.10 4.50 a0. S71 216 9.40 4.50 oy) Ka San 10.40 6.50 3 eS 10.40 6.50 (7) 7x7 x 26 10.55 6.50 (8) 7x 7x30 11.25 6.50 DIAMOND STATE FIBRE COMPANY Bridgeport, Pa., and Chicago, IIl. Branches in Principal Cities Toronto, Canada—London, England CELORON RADIO PANELS universally endorsed by radio experts Celoron will help you get better results from your radio hook-up. It will give your instru- ments thorough, leak-proof insulation. It will help you get greater distance, greater volume. - A Celoron Panel will not soften with heat or deteriorate with age as do rubber and com- position panels. It retains its beauty and its insulating properties indefinitely. Celoron Panel Prices Sizes List Prices Special Prices $34 7x10x}3 $1.09 $1.00 2)7x12x} 1.31 1.00 3) 7x14x4 1.53 1.00 33 7x18x% 2.95 1.00 5) 7x21x% 3.45 2.00 (6) 7x 24x% 3.94 2.00 (7) 7x 26x34 4.25 2.00 (8) 7x30x4 4.92 2.00 If your dealer does not carry Celoron, order by mail In ordering please follow these simple direc- tions: 1. Indicate on the coupon the size of the panel and the size of the cabinet you want. 2. Print in your name and address carefully. 3. Clip out the coupon and attach it to a plain sheet of white paper. 4. Mark on the white sheet the name and address of your dealer and the names and addresses of three friends who are radio fans. 5. Attach your check or money order to the white sheet. 6. Mail all papers to the Diamond State Fibre Co., Bridgeport, Penn. DIAMOND STATE FIBRE COMPANY, Depé, 101 Bridgeport, Pennsylvania Please send me prepaid the following items: Celoron Panel Size No. ‘ ‘ . Price $ Vulcawood Cabinet (without panel)SizeNo. Price$ Check attached $.......... Total $ PORE, baie oc weed de aioe ca atlas Co ike wwitsnn 6 5 RR OE. -: RE © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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America’s greatest Watch value sent you for only $1.00 down! The balance in easy monthly payments. The famous 21- Jewel Studebaker Watch— Insured For a Lifetime! You may choose from 54 new Art Beauty Cases and 8 handsome dial designs. & adjustments —to the second—for heat, cold, isochronism and 5 positions. Sold direct from the maker at lowest prices ever named for equal quality. Mail coupon today for Free Book and Special Offer. Watch Chain FREE For a limited time, we are offering a beautiful Watch Chain FREE. Write now while this offer lasts. WRIT FOR BOOK Mail the Coupon Send at once and get a copy of this book—FREE! See the newest, beautiful advance styles in Studebaker Art Beauty Cases and Dials. Read how you can buy a 21-Jewel Studebaker Insured Watch direct from the maker—save big money—and pay for it in easy monthly payments. Get Free Chain offer while it lasts. 1 coupon today. STUDEBAKER WATCH CO. Dept. J23 South Bend, Indiana Canadian Address: Windsor, Ont. Ask for Ladies’ Bracelet Watch Folder Faccacsesccc. DEBAKER WATCH CO. Dept.J South Bend, Indiana a Gentlemen: Please send me your Free Book cy | Advance Watch Styles and particulars of your $1.00 send your inquiry to nada Canadian Office, Windsor, Ontario BIRING 0.0.02 -cccccecccepoccscovcccsceceoscccaccocsceocs : IND. «ii. n cherdiborsiasauibaiaessocccuedeesscossy 3 City Ss ogee. pepeccepocgoognoqoooss ALE... ..serecccvees k here for Ladies’ [(] Check here for i ‘older. Jewelry Folder. Gh U Wistch Folder BS ReU Ge Meee A EasytoDraw Cartoons When Shown in the RIGHT WAY Some of the cleverest cartoonists and comic artists Jearned how_to draw in their spare time by following Cartoonist Evans’ Simple and al to Learn Method and are now MAKING GOOD MONEY. Send one of your drawings, and let Mr. Evans see if you have ability and receive the Partfolio of Cartoons and full details about the course. It is not expensive. THE W. L. EVANS SCHOOL OF CARTOONING 825 Leader Building | Cleveland, Ohio POPULAR SCIENCE MONTHLY = Wuen the proper Repairing method is followed, Porch Steps the home worker can repair porch steps with very little difficulty. Usually only the first and perhaps the second step give way. To replace eee HH ll em the step itself is a minor repair, but fre- i[ quently one or both side pieces, technically known as “‘strings,”’ need to be replaced. First measure the height of the back of the step, which is known as_ the ‘rise,’ and _ the width of the step or tread, not in- cluding the nosing, RISE SRIREAD PITCH BOARD How the new “string”’ is laid out and used to patch old porch steps or projecting overhang. Make a pattern of cardboard or thin wood from these dimensions, as illustrated. This is known ee as the “pitch board.” It is well worth while to make such a pattern even for a small repair job. Lay this pattern on a new board of the proper width and not less than 1 jn thick, preferably white pine, cypress, or other wood that is relatively durable when exposed to moisture. Then mark out thesteps as indicated and allow for a slight fall of the treads to run off the rain. Cut out the new piece of _ string neatly. Rip the board, if necessary, to make it exactly the same width as the old string. Having removed the steps and risers at the bottom, place the newpiece against the old and mark where the old is to be cut out. Now prop up that side of the steps and cut out the old string. Nail a 4- or 5-ft. length of rough lumber on the inside of the old string after cutting the bottom to fit on a flat stone, some brick, concrete, or whatever is used as a base for the steps. Fasten in the new section of string with nails and replace the old steps and risers, if considered in good enough condi- tion, or make new ones. If neatly done, | this repair will not be noticeable after the new wood is painted.—A. E. ELLING. WALLBOARD, which is now used to such Painting Wallboard a large extent in making repairs around the home, usually is finished by painting. It takes paint especially well so that a good finish is insured if ordinary care is used in wielding the brush. Most wallboard is primed and prepared for painting by the manufacturer. In case the wallboard is not primed, it is always necessary to coat it either with a thin varnish or a glue size. Do the painting, if possible, before the panel strips are nailed in place, unless the strips are to be the same color as the wall- board. The preferred finish is usually two coats either of flat or full gloss paint, although one coat of dark paint may cover sufficiently. The first coat should be thinned with raw linseed oil and tur- pentine. After it is dry, fill all the holes and cracks with putty, colored to match. The final coat should be applied as it | comes from the can. For a still better result, a first coat of flat paint may be followed by one or two coats of enamel. The enamel may be left glossy or rubbed with a fine powdered pumice-stone and water or oil to a dull, smooth finish. WHEN there is sick- ness in the home, the banging of doors can be prevented by the use of a deadening device similar to that found in some hospitals. A piece of rubber of the shape iliustrated is cut from an old inner tube. One hole is slipped over the door knob and the rubber is stretched until the other hole can be passed over the opposite door knob. This prevents the doors being locked, but they will stay closed if shut tightly and no sound will be made, | not even the click of the spring catch.— | Sound Deadener EDGAR WELCH, Oklahoma City, Okla. IS] This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. | i?)

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. Worth n fora | of the 1¥ in, ress, or atively sed to ark out ed and 1 of the 1€ rain. he new string tip the cessary, exactly ridth as ing. emoved nd risers bottom, ew piece the old up that the old of rough 1 string n a flat vhatever

vf string teps and | th condi- | ‘ly done, | ble after ELLING. ow dered (0 a dull, ‘e is sick- e home, r of doors revented e similar A piece

be made, x catch.— , Okla.

3.

| |

——_ GUE

Chicago Kansas City POPULAR SCIENCE MONTHLY \) \\ <4 NG wee

Radio Headquarters Why not buy your set or parts at Radio Head-

quarters? Only tested and approved radio equip- ment is sold. Every set sold by us is guaranteed to give satisfactory results. Radio Catalogue The best Radio Experts made this catalogue—men who devote their entire time to Radio—who are up to the minute with every- thing new, who tell you the best hook-ups, who have selected for you the best tested parts, who have chosen the best sets—so simple that you yourself can easily install them—so reliable that we guarantee them to give satisfaction. Write for your copy of this Catalogue. See for yourself the ESTABLISHED 1872 Portland, Ore. low prices. Buy your radio at Radio Headquarters. Our 53 Year Old Guarantee Ward’s has dealt with the Amer- ican people for 53 years under a definite guarantee of ‘‘ Money back if you are not satisfied.” All our Radio sets are guaranteed to give satisfactory results and back of this guarantee is a proven reli- ability that for 53 years has not been questioned. Address our house nearest you. Dept. 5-R. Montgomery Ward &Co. The Oldest Mail Order House is Today the Most Progressive St. Paul Oakland, Calif.

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

Ft. Worth

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144 BUILDING TRADES NEED TRAINED MEN Thousands of good positions at good salaries HE building trades are still booming. ‘Trained men are in de- mand at good salaries. Government experts estimate that billions of dollars will be spent for construction this year. Today the most vital need of this great building program is men—frained men— men who can step right in and do the skilled work that building construction requires. There is a simple, easy, practical way by which you can prepare for a better posi- tion, at a bigger salary. You can do it right at ‘home, in spare time, no matter where you live, through the International Correspondence Schools. A recent investigation of 13,928 students en- rolled in I. C. ‘S. Building Trades Courses showed that 1921 had become Architects; 246 had become Designers; 494 had become Chief Draftsmen; 2827 had become Draftsmen; 1845 had become Contractors; 211 had become Assistant Foremen; 4030 had become Foremen; 2354 had become Superintendents. You, too, can have the position you want in the work you like best; an income that will give you and your family the home, the comforts, the luxuries you would like them to have. Mail the Coupon for Free Booklet INTERNATIONAL CORRESPONDENCE SUHODLS Box 7643-D, Scranton, Penna. Without cost er obligation on my part, please tell me how I can qualify for the position or in the subject before which I have marked an X: TECHNICAL AND INDUSTRIAL COURSES 5 Architect Electrical Engineering Architects’ Blue Prints [Electric Lighting [j Contractor and Builder Mechanical Engineer [j Architectural Draftsman [) Mechanical Draftsman [j Concrete Builder Machine Shop Practiee _j Structural Engineer Cj Railroad Positions Chemistry © Pharmacy Automobile Work Airplane Engines Gas Engine Operating Civil Engineer Surveying and Mapping Agriculture and Peultry Metallurgy O Mining Mathematics team Engineering (©) Radic BUSINESS TRAINING COURSES Kinks that Have By E. C. Fellows i: D, YOU must have worked on the E, Pyramids!”’ remarked Joe, as he stopped to watch me put the fin- ishing touches on a slot in a boring bar. “What makes you think so?” “Oh, because you’re always up to some kind of a stunt that’s all hand work,” said Joe. ““Well, perhaps this is an antique way of doing a slotting job, but when you get a little practice, it’s about as quick and easy as any other way. A narrow slot like this is a mean job on a milling ma- o—~ SS INISH SLOT-CUTTING METHODS NUT-HOLDER GRIPPED IN CHUCK Salesmanship Business Management Advertising Industrial Management Better Letters Personnel Organization Show Card Lettering Traffic Management Stenography and Typing Business Law Business English Banking and Banking Law Civil Service Accountancy (including C.P.A.) Railway Mail Clerk Nicholson Cost Accounting Common School Subjects Bookkeeping High Scheel Subjects (| Private Secretary [Illustrating OOSpanish (French SE Es EE Re ree See cs ee Oe eON ir TCE Street 3-6-24 BB BTOOB «0.00 0000cccccceccccccecccccccnsece scores coccoo sconce scnsoscososesesseescssec ces ic sensnebens Occupation... Persons residing in €anada should send_ this coupon to the Intornatiena). Correspondence Schools Canadian, Limited, Montreal, Canada. Do you kn of two @lamond3 0 of equal size one may be worth a hundred times as much as the other? Who can dis- FREE! § tae 3 tinguish them but an expert? My Diamonds chort, easy course wiil make you a iamond expert in a few months! if you enroll at aged et it before. you buy your next Bea eeomeyt b diamond expert and go for if ais 3B or Sed aoitalt We will sbow 3 ‘$33 $5000 to $15, 000 a Year! a diamond expert ‘and. become i Business i is a Oe s business. Sooces in any - & A aie — in the diamond business means up to to $15,000 a year! t’ Millions of dollars are oo 5 ae. ‘A °, id = every year 3 diamon ewelry houses everyw ere pee iamond exper’ ways pay high for expert opinions. ‘Diamond e i WRITE FOR FREE BOOKLET *Paying Diamond Knowledge’’ be sent to bsolutely FREE! Pa a 4 new and amesing sad hag facts about | diamon: de. nen NOW! CODINGTON SCHOOL OF DIAMONDS 3457 Sunnyside Dept. 202 Chicago, IiL | chine, and I’d much | rather finish it up | with my set of four | chisels. You have | to drill holes to get | the stock out, any- | way.” The chisels I use | are illustrated above. Short pieces of GTi channel iron of dif- ferent sizes help to speed up work on the drill pre8s. For holding shafts and other round work these irons are about as good as a V block where extreme accuracy is not a factor. They also are handy for holding many small, odd-shaped pieces. Tools for slotting, bottom inside and out, and along the top edges for holding round work parallel. Speaking of saving effort, there’s nothing that takes more of a man’s time than looking up bolts, nuts, and washers. il have solved this problem to a large ex- © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. FORGED BORI NG TOOL BORING-TOOL FOR SMALLER HOLES work-holding fixtures, and handy shop racks If desired, they can be planed on the Divider marks new - starting point ~ — My Time tent by arranging racks as_ illustra- } ted. This is a job for the helper or one of the appren- tices. o For facing and chamfering nuts I have on hand sev- eral sizes of nut arbors similar to that shown. A thread is cut on each end so that one arbor will serve for nuts of two different sizes. These arbors are held in the chuck by gripping the central portion. I save a lot of time and valuable tool steel in lathe work by making up special forms of tool bits for lathe toolholders. Of course, there are instances where forged tools are preferable. When mak- ing a forged boring tool I prefer the shape shown; the feature being that the taper comes on top where there is most room and adds to the stiffness of the tool. F°® boring small holes I make up tool- bits as needed for the toolholder. In the illustration below are shown a boring tool and one for outside threading. When boring large bushings and in similar work I find the toolholder makes a rough-and-ready tool where the length of the holder is sufficient to reach the entire length of the bore. A toolbit is bent to an angle and the nose is ground for boring. A tool used in this way will take a much heavier cut than the conventional boring tool, and where there is a lot of metal to be removed, its use saves time. When I have a threading job to be done in an old lathe without a dial indicator and the lathe has to be stopped for any reason, I use a divider to mark a point from which to make a new start, instead of running back to the first mark, which is the usual way. I set the divider to any number of equal inches, according to the lead screw and the number of threads to be cut, as ghown at the top of this column, and run the carriage back to it. BENT TOOLBIT OUTSIDE THREADING boring, and threading; Few shops have extension handles for taps to get into inaccessible places, as i certain auto-repair work. Often holes of this kind can be tapped for oversize bolts or retapped by finding a hexagon nut that can be driven over the square end of the tap and then using a socket speed wrench on the nut.—C. CARPENTER. See page 33. to Y th yc cos Sn pa yo th De mi

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new oint * of two ire held: central able tool P special holders, S where len mak- he shape the taper ost room ool. | | 2 up tool- yider. In a boring ag. s and in r makes a length of the entire bent to an or boring. ce a much nal boring f metal to job to be ut a dial r and the as to be for any I use a to mark a om which ce oa new nstead of back to st mark, ; the usual I set the to any of equal according lead screw number of to be cut, vn at the he carriage 1andles for laces, as in en holes of ersize bolts xagon nut square en cket speed ARPENTER. 33. OUR headlights bore a hole in the dark to the road sign and you read the bad news. Your fingers nervously explore in the gloom for your tools, they fumble at a stubborn nut, the w rench slips— it doesn’t fit. You try another and it won’t reach in. Yow work, tug and wonder if you’ll get going. At night —on a lonely road like this—you will doubly appreciate the speed and efficiency of Snap-On Wrenches in helping you out of your trouble. Don’t be at the mercy of hit or miss tools any longer. It’s too costly. Go to the nearest Snap-On Dealer now—ask to see the Set of Snap-On Wrenches scientifically selected by our engineers for your particular make of car. The Snap-On interchangeable principle gives you—in a mere handful of high grade steel units—wrench combinations that will reach, fit and easily turn every nut and bolt. Genuine Snap-Ons are for sale by most good Hardware Dealers. Learn how to cut operating costs of your car in half— mail coupon for free illustrated folder. SNAP-ON WRENCH CO. Manufacturers—Milwaukee nap-on INTERCHANGEABLE Socket Wrenches Look for the name—without it no wrench is a genuine Snap-On MOTOR 1 TOOL SPECIALTY CO., Distributors 14 E. Jackson Blvd., Chicago, III. Gentlemen: Please send me full particulars about Snap-On Kit (If interested in Master Mechanic’s POPULAR SCIENCE MONTHLY When Trouble Comes at Night Far from Help, Dealers Install this Snap-On Display. Cabinet | and supply the complete socket wrench needs of car owners and all other wrench. users in your community. Remark- ably low shelf invest- ment, quick turnover. Write for details of our Sales Plan. One tow-in job will-more than pay ‘for the selected Snap-On Set for your car similar to this Buick Set. It will be tremen- dously valuable to you in your spring overhauling work—and you will always have it under the seat for road emergencies. © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. i 1" Snon-on us om area i See page 33.

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POPULAR SCIENCE MONTHLY

THEY SAY OF THE PFANSTIEHL MODEL 7 “People now want trouble-proof service and purity of tone. There is no distortion, however great the amplifica- Two stages of audio amplification—low ratio, of course, clear, natural tone at any distance. ... tion. ... It comes in like velvet.... The new Pfanstiehl ... givesa to give perfect quality, with all the volume desired.” Pfanstiehl amplifies with Thordarsons

THEY SAY OF “It brings in distant stations distinctly. volume.” THE HOWARD NEUTRODYNE It has natural tone qualities, It has remarkable Howard amplifies with Thordarsons

THEY SAY OF THE RADIODYNE ‘“‘When you own a Radiodyne you can hear singers’ voices and orchestral harmonies faithfully reproduced thru the loud speaker .. . so clear and distinct that you lose nothing.”’ Radiodyne Ampblifies wi h Thordarsons

When Better Transformers ge Roe Se N drill press “4s ——— or slotter i [+1 %

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lotter. It locking.— land, Md. March, 1925 POPULAR SCIENCE MONTHLY 147 ; the time . fastening SARGENT PLANES a oe Sargent Siee! Block Flane Sargent Auto-Set ° Bench Plans The beauty of Sargent Planes is not in SARGENT Planes are beautiful tools— in design, materials and fineness of construction and finish. But the beauty of them that’s most appealing is in the way they do their work. Always smooth and clean-cutting, with never a murmur! And ‘‘murmur’”’ isn’t simply a figure of speech. As you undoubtedly know, the im- portant part of any plane is the cutter, and the next thing is to make sure that it will not chatter or murmur when going across or against the grain. SARGENT & COMPANY, Mfrs., their looks alone Here are two of the advantages you get in Sargent Planes: 1—a cutter of finest chromium steel, tough, wear- resisting, edge-holding. 2—absolute rigidity when the cutter is in place. Of course there are other points that will interest you—points that make these two moderate-priced planes most desirable for every home and school work-bench. See Sargent Planes at your hardware dealer’s and write us for booklet, which gives detailed in- formation about them. 50 Water Street, New Haven, Conn. © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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148 POPULAR SCIENCE MONTHLY March, 19235 It Has the Full Sweet Resonance of Our Upright Horn The outer end, or bell, of the horn in our cabinet model loud speaker does not touch anything. This, together with a long expansion chamber, gives it the same freedom of vibration which goes to make the Bristol horn type Loud Speaker such a It also has the resonant, sweet-toned instrument. same high-grade electromagnetic sound mechanism. Not only is it a handsome loud speaker, but one worthy of the best radio set that money can buy. Model C $30.00 BRISTOL“ Loud Speaker Model S $25.00 There are five Bristol Loud Speakers, priced from $12.50 to $30.00. If not at your dealer’s, write for Bulletin No. 3020-CA. The Bristol Company Waterbury, Conn. © and sizes. Delivered free on approval ex- GARY press prepaid for 30 Bays" Free Trial. if desir . Possession and ‘ se at once on our liberal WV ui Monthly payment plan. Bicycles lamps, wheels. equi i ual prices. or marvelous new, prices, wonderful 30 day trial offer and terms, - Write f ‘ % Mead San coma exe. NY $21.50 and up. ipment at half us- TUNING 2—Increases vol used. 209 E. Sixth St. NN Kt At il THE COIL WITHOUT LOSSES E SAM MASTER COIL 1—Wound on moulded hard rubber. ume 50% to 250%, also selectivity, over old type. 3—Eliminates all adhesives. 4—Laboratory tests prove it is the only Coil worthy of the name Lowloss. FREE { Ask your dealer or send * us four cents in stamps for wiring diagrams of circuits in which this remarkable coil can be UNCLE SAM ELECTRIC CoO. Plainfield, N. J. | $150 * $300 Prorit 1 Day Battery Charging Brings trade and big profits. Only $35 cash brings complete equipment tor One Day battery charging. Small monthly payments. Free trial ; 4 Or moneyback guarantee. Write for 4 Free Bulletin 20 HOBART BROS. CO., Box P3, Troy, Ohio. HB Skrrexy CHARGING ~ “Old Town Canoes” Where’er the smiling stream may beckon Get an “Old Town” this summer and realize the joy of a truly fine canoe. ‘Old Towns” are beauti- ful canoes. They are patterned after real Indian models. Invest in an “Old Town” today and you will re- ceive dividends in happiness for years to come. “Old Town Canoes” are low in price. $64 up. From dealer or factory. ’ g ? The 1925 catalog shows all models in full colors. It is free. Write for your copy today. OLp Town Canor Co., 1593 Main Street, Old Town, Maine, | ‘| month. | pull of the machine, the tap chuck is Grinding Drills and in Tapping HE twist-drill grinder and the electric tapper shown below are tools ro. cently developed to supplement the elec. tric hand drill, the many uses for which were described in the article, “What You Can Do with the Aid of a Portable Electric Drill,’’ in this department last The twist-drill grinder will sharpen quickly and accurately either straight or taper shank twist drills up to %& in, in diameter, ; Electrically driven bench or pedestal kd grinder for sharpening twist drills and : portable tapper with automatic reverse The drill is fed to the dish grinding wheel by means of a micrometer screw feed. Heretofore many garages, service sta- tions, and small machine shops have hadto depend upon free-hand methods of grind- ing drills. The new machine therefore has a wide field for service, especially as the necessity for grinding twist drills to the correct angle, with proper clearance and with both cutting lips exactly the same length, is universally recognized. The electric tapper differs from an elec- tric drill in that the gearcase is so de signed that the tap turns at a speed of 350 r. p.m. By a slight backward reversed automatically and the tap backed out of the threaded hole at twice the speed with which it is driven in. It will tap holes in steel up to 4 in. in cast. iron up to %% in., and in brass or aluminum up to %% in. Wooden Wedge Stops Chatter Hew to stop chattering is a problem that confronts every machinist at some time or other when turning shafts or other round work between center. When the piece is not being supported by a steady rest or a follow rest, the chatter almost always can be prevented by wedg ing the dog in the driving slot of the face plate, provided the piece is not unusually long. A wooden wedge may be used of even a small piece of old belting or cotton waste. © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. wit! as j him his

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Ei ing electric ls re. he elec. T which hat You ortable ent last sharpen aight or r shank 10 % in, liameter, or pedestal it drills and atic reverse grinding ter screw rvice sta- ave hadto 3 of grind- refore has ly as the ills to the rance and the same d. m an elec- is so de 1 speed of backward chuck is the tap le at twice driven in. Y4 in; in n brass or Chatter a problem achinist at ning 8 en centers. ipported by the chatter od by wedg- of the face ot unusu be used of ng or cotton ——aa 33. HERE’S a lot more satisfaction in T owning your own tools than bor- rowing from others. The next time a perpetual borrower comes to you and says: ‘‘Lend me this or that,” see if you can extract a prom- | ise from him to buy the tool for himself not later than next pay-day. Never mark the size on a tool that is made in the shop unless that size is ab- solutely right. Some one else may pick it up without measur- ing it and spoil a piece of work. Oil your ma- chine each morn- ing before start- ing up. Old Bill, machine- shop foreman Never place files, heavy wrenches and tools, or rough castings on the ways of the lathe, not even an old lathe. It is dangerous to run emery wheels with the guard removed; if you value your head, keep the guards in place. A good mechanic is never satisfied with anything less than his best. Try to help the other fellow as much as you can and make his job easier for him—some day you may be glad of his help. Safe Method of Putting Belt on Line-Shaft Pulley a [‘ MANY places it is difficult to put on long line-shaft belts after they have been removed for shortening or when they have run off for any reason. It is dangerous to try to do this while stand- Ing on a ladder. A safe and easy method is to tie the belt on the under side of the pulley as shown. Have another man stand at the starting box or clutch shifter and when all is ready let him apply the power slowly. The belt will creep up over the tim of the pulley. When the rope reaches the top, signal to stop and then untie © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. POPULAR SCIENCE MONTHLY 10 SHAVES FREE Send the Coupon si «file. We must prove The claims made for this unique Shaving Cream before you buy it —please accept a test By Chief Chemist GENTLEMEN: You hear men talking about Palmolive Shaving Cream. Any man who uses it will spend 30 minutes, any time, urging its advantages. Palmolive has quickly become leader in its field. Only great merit, you'll agree, can account for so dramatic a success. Now we ask you the favor of a trial. 5 New Delights Over 130 formulas were tested and discarded before we offered it to you. It embodies the 4 things 1000 men told us they wanted most in a shaving cream, plus a 5th—strong bubbles, the supreme requisite of all. Won’t you let us send you 10 shaves free? ty) delights Now in justice to yourself and us, make the test. Simply mail the coupon. To add the final touch to shaving luxury, we have created Palm- olive After Shaving Talc—especially for men. Doesn’t show. Leaves the skin smooth and fresh. Sample free with the tube of shaving Cream. Clip coupon now. THE PALMOLIVE COMPANY (Del. Corp.), Chicago, Il. PALMOLIVE 1—Multiplies itself in lather 250 times. 2—Softens the beard in one minute. 3—Maintains its creamy fullness 10 minutes on the face. 4—Strong bubbles hold the hairs erect for cutting. 5—Fine after - effects, due to palm and olive oil content. and a can of Palmolive After Shaving Talc Simply insert your name and address and mail to Dept. B 955. Address for residents of Wisconsin, The Palmolive Company (Wis. Corp.), Milwaukee, Wis. Address for residents other than Wisconsin, The Palmolive Company (Del. Corp.), 3702 Iron St., Chicago, Ill.

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= $95 an Hour! “Every hour I spent on my I. C. S. Course has been worth. $95 to me! My position, my $5,000 a year income, my home, my family’s happiness—I owe it all to my spare-time training with the International Correspondence Schools!” Every mail brings letters from some of the thousands of I. C. S. students telling of promotions or increases in salary as the rewards of spare-time study. What are you doing with the hours after supper? Can you afford to let them slip by unimproved when you can easily make them mean so much? One hour a day spent with the I. C. S. will prepare you for the position you want in the work you like best. Yes, it will! Put it up to us to prove it. Mark and mail this coupon now! —— —— ee oe — INTERNATIONAL CORRESPONDENCE SCHOOLS Box 7642-D, Scranton, Penna. Without cost or obligation on my part, please tell me how I can qualify for the position or in the subject before which I have marked an X: BUSINESS TRAINING COURSES Business Management (J Salesmanship Industrial Management Personnel Organization Traffic Management Show Card Lettering Stenography and Typing Business English Civil Service Railway Mail Clerk LJ Advertising Business Law Better Letters Banking and Banking Law Accountancy (including C.P.A.) Nicholson Cost Accounting Bookkeeping Cemmon School Subjects Private Secretar: High School Subjects Spanish French lustrating TECHNICAL AND INDUSTRIAL COURSES Electrical Engineering ( Architect Architects’ Blue Prints Contractor and Builder Architectural Draftsman Concrete Builder Structural Engineer Chemistry (1) Pharmacy Automobile Work Airplane Engines Agriculture and Poultry Electric Lighting Mechanical Engineer Mechanical Draftsman Machine Shop Practice Railroad Positions Gas Engine Operating Civi] Engineer Surveying and Mapping OM Metallurgy ining

Steam Engineering (1 Radio Mathematics Name. Secanes Street 3-6-24 sR ch chiatient cashailanesbbaeeshrnevnshenmmevtalnnehivnledenset$ceeseess 50 RNG icra 50s a. ndok osc pebassepevenunee MIDs. -sceccusuvpssusbvsecauaebioeerecbevs Sica a beck de Separgeenntebseuibids pocbbuceborncnspasgnccvonnnpe> Persons residing in Canada should send this coupon to the International Correspondence Schools Canadian, Limited, Montreal. Canada NEW Low RIC = a rs

manufacturer’s prices. == Get rT =O SSsCisCRamges' = Save 1-4 to 1-2 on stoves {ane — 2 ee ranges, furnaces, an { i $H QS housenoia oods during the = test sale in our25years” Up istory. Cash or easy pay. ments—terms as low as tee. 24< rae CoV Ceviive yay bO} buco am comm (0) ae

POPULAR SCIENCE MONTHLY

i Better Shop Methods Winning a Shop Race (Continued from page 100) drill. The base of the machine had a hole to guide the lower end of the bar. He found.some clamps so that he could fasten the wheel in place. He turned the pulley so that one of its spokes was against the column. ‘“*To make sure that it does not turn and spoil my setting,’”’ he said by way of explanation. A machinist came up with some calipers and measured the bar. **T’ve been making a bushing for the table arm,” he said; ‘‘have it ready for you in about two minutes now.” 7 SFON got a long bar about % in. square. It looked like key steel. He bent one end of it to a hook shape and put the other end in the cutter hole of the boring bar. He swung it around to center the wheel by the rim. Then he turned the hook up out of the way so that he could see if the rim was at right angles with the axis of the bar. He was just clamping the wheel firmly in place, all trued up, when the bushing was brought over to him. Old Bill also came along. “There is so much to take out of that hole that I thought you could make faster time if we had some support closer to the cutter, especially since the spindle is somewhat worn,” Old Bill said. ‘‘ That’s why I had this bushing made for the table arm.” Old Bill turned to Johnson. “Laton has this job going well now, so why don’t you look about the shop, and see how some of the other things are done,” he suggested. ‘“‘If you will see some of the hard things that we do, maybe you will understand how it is that some jobs take longer to do than you think they ought.” Old Bill and Johnson started through the shop. They had not gone very far when they saw several men gathered around a lathe in attentive attitudes. One of them was standing on the carriage with a red hot bushing in a pair of tongs. Another hada flatter. A third had a sledge ready. HERE was a shaft in the lathe and the men were putting a bushing on the end of it. It went on very nicely, | and almost before Johnson could say any- | thing, they were cooling the bushing with | water. ‘* Another trick to save money for our customers,”’ Old Bill explained. ‘‘Thisisa spindle that runs very fast. It wore down so much on this bearing right at the end that they were about to throw it away and have me make a new one. There was nothing else the matter with it, only this bearing got so small that it kept on run- ning hot. The pulley is right next to the bearing, and the belt is very tight. In- stead of throwing the shaft away, we make a steel bushing and shrink it on the shaft, which then is finished to size. ‘‘This is for a planing mill in about the same fix that you are. It can’t work until we get this fixed up. So you see we have to know how to do things in a hurry.” (Continued on page 151)

The Children’s hour is Radio hour are sensitive to the most delicate tone shading. Their use in your receiving set insures clear, well- rounded reception. Combined with this supersensi- tiveness is a rugged durability, Cunningham Tubes serve long and well. Since 1915 Standard for All Sets bi ng C301, €299, C300, Cll, C12 n the orange and blue carton Patent Notice: Cunningham tubes ave covered by patents dated 2-18-08, 2-18-12, 12-30-13, 10-23-17, 10-23-17, and others issued and pending. oe LS Kew Leoz : + HOME OFFICE NEW YORK 182 SECOND ST. SAN FRANCISCO CHICAGO

BIG NOVELTY BARGAINI (0 Cts, Us THROW oe WA YOUR

Into a trunk, under the bed or anywhere. Lots of Fun fooling the Teacher, Policeman or Friends, Barrels of Fun, THE VENTRILO, a little pray fag oot poe the mouth out of sight, used with above for Bird Calls, etc, Sent with full im structions; anyone can useit, NEVER FAILS, Alsoa $2 PAGE BOOK ON VENTRILOQUISM, Formula for Secret Writing, 12 Money RA Y Wo the. marvelous NOVELTY X-R Y NDER ith it you can rently see the bones { fi . \Tlp, lead in pencil, etc; lots of cn wii me U'fit, Also 10 Big Magic Tricks Free - 4 withevery orden All the above Novelties = by prepaid m for ~ VENTRILO COMPANY j Dept. 756 Norwalk, Conn, LARGEST and OLDEST Mail Order Housein Connecticut, LATEST WHOLESALE RADIO CATALOG REE. imply sen name

Ss TODAY for big Live dealers and agents wa STANDARD RADIO CO.. 104 East 13th, Kansas City, Mo “LIGHTING FIXTURES" Ready to hang. Direct from the manufacturef. | Completely wired incl glassware. Send for Catalogue No. 2% (Just off the press) Special proposition to Dealers ERIE FIXTURE SUPPLY 60. Desk A. Erie, Pa.

© This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. 48-page catalog — of latest radio goods at Wholesale. '

With ¢) With a

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4 icate your well- ensi- ility, long ots Cl2 L 28 L and a _——_ getter Shop Methods Winning a Shop Race (Continued from page 150) of} The two went on between the rows of Jathes and drills and shapers. On the way through the welding shop, Old Bill stopped to look at a header being made. “Making it up with welded joints gives much stronger and more lasting job,’’ he iq. ‘This is for an ice plant, and would have to have three screwed joints for each one of these connections. They are hard to make tight, and the threads almost always rust through before the pipe. By welding it all together in one solid piece we get @ much better job.” “But what is he bending that pipe for?” Johnson asked. “tT allow for the shrinkage of the welds,” Old Bill replied. ‘If he did not PIPE KINKED SLIGHTLY =, WELDING A PIPE HEADER SHAFT TURNED TO FIT BUSHING mo BUSHING y REPAIRING WORN JOURNAL hig STEPS IN MAKING WELDLESS CO RING FOR GEAR Avoiding shrinkage strains in welding pipe, and other repair methods used by Old Bill do that, the welds would be strained when they cooled, and might leak. But by kinking each of these pipes just a little, it can straighten out and compen- sate for any excessive shrinkage strain. The bends are so slight that they will hardly be noticed when the job is all done. In fact, the welder is so good that he knows just exactly how much to bend to or them straighten out when they are cool.” They passed through the welding shop tothe blacksmith shop. The blacksmith Was apparently splitting a heavy piece of seel bar. Old Bill pointed to it. “There is something that you will be terested in,” he said. ‘Perhaps you noticed a gear come in with most of the teeth broken out? We have that gear in the lathe now, turning off all the teeth. We'll put a steel ring on and then cut new teth in the steel part. Of course these teeth will be stronger than the cast-iron wes, which will make it a better wheel anit was before. In making a ring for this sort of job, we make it without any Welds, so that there is no possibility of a Weak place anywhere. For the smaller Migs we use steel plate and cut it out with the cutting torch, but for one this tge we have to forge a ring. We start wth a chunk of steel about 4 in. square (Continued on page 152) ; POPULAR SCIENCE MONTHLY 7 &O Ly o aly fy See ' ry == ONE hand on ONEdial for Juningin/ Magnavox Receiving Sets TRE-S5 (as illustrated) encased in carved ma- hogany cabinet; price includes M4 Repro- ducer . . $125.00 aS VEN though the Magnavox A Ns NG single dial Station Selector sea) has displaced the “old style” complicated tuning arrange- TRE-50 in carved . mahogany period cabi- ments, this remarkable feature alone net with dust-proof | : 2 : Magnavox Repretce wouldnothavemerited thepraisewhich 150.00 ° e every owner gives his Magnavox Set. shat mami It is by its sheer musical quality, in addition to its P unusual simplicity, that the Magnavox 5-tube tuned M4—the most efficient radio {frequency circuit retains the user’s lasting unit ever designed to _ . operate without ex- admiration. ssiainaianiaiaadataiaated As pioneers in the design and manufacture of radio Electro-dynamic | reproducers, Magnavox engineers were thoroughly Reproaucer equipped to master the problem of beautiful tone. The original radio re- producer, famous throughout the world. With Volume Control. R3, $35.00 RZ, $50.00 If you already own a receiving set, a Magnavox Reproducer will wonderfully enhance its daily use- fulness for family and friends. Magnavox Radio Products are carried by ® reliable dealers. Illustrated booklet on request THE MAGNAVOX COMPANY, Oakland, Cal. New York: Chicago: San Francisco: 350 West 31st St. 162 N.State St. 274 Brannan St. Canadian Distributors: Perkins Electric Limited Toronto, Montreal, Winnipeg Tool Cases for Machinists, Car- penters and Tool Makers; none better; thirty styles. Quarter- ed oak and metal cov- ered. Ask for booklet. **Built for Service”’ a The Pilliod Lumber Co., Swanton, Ohio fir ble to average Over $1! am WEEK. Could do more only I do no IS} This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. put in much over half time. Person- ally I think it is the easiest sold ar- has merit L.R. Gra- ON GUARANTEED TYPEWRITERS ' “month, Frank DePries has been with us six Limited quantity fully guaranteed eare—f eek. Hun- >) standard make writers. § Days them OW Sreds of pre pmctinstn Pasi | ‘375, $100 w Pree ene Tithe ei week. We need more men to fill unoccupied ae 2 dreds of prospects makes selling easy a Fg A a } ato hg shops, farms, homes, auto and truck owners, hos- . tion and Special Sale Bulletin. Pivtl'in wonld,, “Write quick sbout this im ? mith Typewriter SalesCo. ind in world. te quick a 321-360 E. Grand Ave., Chicago, Ill. THE FYR-FYTER CO., G49 Fyr-Fyter Bldg., Dayton, 0.

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Big Money and a Barrel of Fun First-Class Saxophonists make big money, and the work is easy and pleas- ant. You might easily become a wizard like Tom Brown or Ross Gor- man, or a great record-maker like Clyde Doerr or Bennie Krueger or Jos. Smith. $100 to $500 weekly is not unusual for such musicians to earn. Talk About Fun! There is always a good time for the Saxophone player. It's the ideal in- strument for social entertainment. It is a key to social popularity. At parties, everywhere, the Saxophone player is the center of attraction. Easy to Play-Easy to Pay The Saxophone is the easiest of all in- struments to play. You don’t have to “study”? it as you do other instru- ments. There’s no practice drudgery. You don’t have to be ‘“‘talented’’. 3 LESSONS SENT FREE with the instrument start you. In a week you can play popular airs. Besides being so easy to play - we make it very easy to pay for one of these Buescher Saxophones with our simple eee of deferred payments. Play and earn while you pay. § Free Saxophone Book -Very interesting. Tells all about the various Buescher Saxophones, with pictures of the famous professionals and orchestras. Send coupon for a copy. Mention any other instrument in which you may be interested. 155 BUESCHER BAND INSTRUMENT Co. Everything in Band and Orchestra Instruments 480 Buescher Block Elkhart, Ind. OR A A NE A AS A TT plete Band Instrument Co., a 480 Buescher Block, Elkhart, Ind. Gentlemen: | I aminterested in the instrument checked below: Saxophone. ..Cornet... Trombone. ..Trumpet.. (Mention any other instrument interested in) | ER ea so wake sae oa oem Ack ayek es ] POPULAR SCIENCE MONTHLY Winning a Shop Race (Continued from page 151) | and long enough to weigh the same as the finished ring. Then we flatten it down to | near the finished thickness, punch a hole | near each end, and split the part between. | The split is then opened out until the | piece is ring shaped, and the blacksmith | draws the metal out to get the required | diameter. That makes a much better job | than welding, and doesn’t take much longer.” The pulley was ready by this time. Laton was taking it off the machine when Old Bill and his guest got back to the machine shop. - Old Bill stretched his neck, readjusted his hat and looked at his watch. It was eleven o’clock. The pulley would be running by night. So would the wood- working spindle, and a number of smaller items, each one of them ‘‘the most im- portant rush job in the shop.” Automatic Feed Saves Time in Punching Thin Metal Stock — punching small pieces from metal ribbon that is wound on a reel, the operator usually unwinds some of the stock on the floor, and then pro- ceeds to punch it until used up, after which the process is repeated. On thin Each stroke of the press automatic- ally turns the reel of thin metal ribbon stock, this occasionally results in a tangle, with loss of time and waste of material. Stock of this kind can be fed automatic ally by the method illustrated. The shaft that supports the reel carries a ratchet and pawl, connected by a lever with the press pedal. The yoke carried on the pedal is slotted to permit movement of the lever within it. The top of the yoke carries a setscrew by which the movement of the reel is adjusted. Every time the pedal is depressed, the reel is advanced a certain amount. By permitting the stock to sag toward the floor, between the reel and the press, it is kept from loosening on the reel.—R. H. Kasper, Philadelphia, Pa. SMALL pieces that are made of machinery steel can be casehardened quickly by applying cyanide directly to the piece when hot. Draw the piece out of the fire and sprinkle the cyanide over it or on the point to be hardened, using a long- handled spoon or a piece of flat iron. Re- place in the fire and allow the cyanide to soak in. The operation may be repeated several times, according to the depth of penetration desired. Then plunge the piece in cold water. Over 1000 other bargains. Furni Silver, China, Blankets, Stoves, etc, Save ie res, at our Factory-to-Family prices, Pay as litt ome down; up to a year and a half to pay belaes $3 all your Furnishings at once—pay as you use. - sands buying this new way. » Thou. s Big Catalog FREE New Spring ‘‘Larkin Book Bettey Hi omes."’ Shows everything i porch, dining-room, bedroom then’ Bargain Prices on famous § . nola Phonographs. Also Symphonic Pies E yer, Pianos fa genuine M » Walnut’ ‘um ak. Free trial. Up to4 to stile ntatstad ane” et ec bt — |} © Home Furnishings Cj Pianos or Players O Phonographs Cut out this adv.—write ‘ for FREE Doon maY Litrhitt Co te Dept. 340, BUFFALO, N. Y, Peoria, Ill. Chicago, Ill. “DON'T SHOUT” “T hear you. I can hear now as wellas anybody. ‘HOW?’ With THE MORLEY PHONE. I've a pair in my ears now, but they are invisible. I would not know I had them in, myself, only that I hear all right.” The Morley Phone for the DEAF is to the ears what glasses are to the eyes. Invisible, ' sieael eS i — , less and harmless. Anyone can adjust it. er one hundred sand sold. Write for booklet and testimonials. al THE MORLEY CO., Dept. 797, 10S. 18th Street, Philadelphia AGENTS ~ tien with Stuart’s Stain Remover. Removes iron rust, mildew, ink, medicine, grass and fruit stains. Bleaches clothes, cleans straw hats. Every home, every store, every office is a prospect ¥e my and agents are making $8 to $10 a Day & This is part of our line of over 200 household specialties that are making other men and women independent. Some good territory open. Write at once for Outfit offer and Free Sample, C. H. STUART & CO. 868 Lake St., Newark, New York Fine Tone $20 Musical Instruments We have a wonderful new sopyrigl ted system of rl S8R at mail! To first pupils in each locality we will superb Violin Tenor Banjo, Ukulele, ;Hawaiian-Guitar, dolin, Banjo-Ukulele, Banjo- Mandolin, Cornet ot lutely free. teach Piano and Organ. Very small lessons only, -sFour lessons will teach you several 100,000 successful players. We guarantee oncoe Complete outfit free. Wri lay, Dept. 4 Slingerland Schoo! of Music, 1815 0 St. Chicago, AGENTS 6rrorir Eb SEE A Hil | GENUINE GOLD LEAF LETTERS Guaranteed to Never Tamish Anyone can put them om prs and o windows. Enormous demand, large profits. Paul Clark st Smallest day $28.70. Rv. Reel made $ 20 in two months. Write a free sample @ ii “4 offer to gene 433-E_N. Clark, Chicago METALLIC LETTER CO. © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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SBopks oy 8 Ree. We etl s z as : i;

March, 1925 Better Shop Methods Bench Riveting Machine Speeds Production of Small Work By H. E. Barber UILT right on the bench and run by a B belt from the line shaft, this sturdy little riveting machine speeds up all kinds of small riveting. It will rivet over the heads of long, slender rivets without bending them at a speed of 2000 or more strokes a minute. Dimensions are not given, as the ma- chine may be built of any size most suit- able for the kind of work to be handled.

The hammer is attached by a taper fit in Pressing the foot lever causes the cam D to vibrate the hammer rapidly and forcefully the end of the bar, A, which is bolted to shaft B. Shaft C has a cam D riveted to its circumference. not actuate the hammer bar because of work is on the anvil G, the foot lever is pressed to operate the hammer. The power of the hammer is derived from spring E. For fast work the pulley should be large enough to give the cam shaft a speed of from 2000 to 3000 revolu- tions a minute. The four bearings may be ordinary cast Babbitt bearings or even wooden blocks with Babbitt linings.

the tension of the spring F. When the | POPULAR SCIENCE MONTHLY

‘Just use ordinary tools on this panel— built to order for radio a good job on a Radion Panel. Just the usual tools found around any house will give you clean-cut, workmanlike results. You need not have the slightest fear of chipping. Radion is the easy material to cut, drill, and saw. It was developed to order by our engineers to meet the de- mands of radio set builders. There is nothing quite like it for real results. Highest rating as radio-fre- quency insulation ¥.. don’t need special tools to do Authoritative laboratory tests give Radion the highest rating as radio- frequency insulation. That means that losses from surface leakage and dielec- tric absorption are exceptionally low. And low losses for beauty alone. It’s useful, too. Moisture and dirt cannot gather to cause leakage and leakage noises. Radion resists warping. It’s strong. It’s moisture proof. It comes in eigh- teen stock sizes and two kinds, Black and Mahoganite. Better performance will make it worth your while to ask for Radion by name, and to look for the name on the envelope and the stamp on the panel. Radio dealers have the exact size you want for your set. Send for booklet ‘‘Building Your Own Set’’ Our new booklet, “Building Your Own Set,” giving wiring diagrams, front and rear views, showing a new set with slanting panel,

mean clearer reception, sets with the new more volume and more distance. You can see _ that Radion is different by Other Radion Products The same qualities of low-loss insulation and = attractive appearance characterize Radion dials (to match

Radion built-in horn, lists of parts and directions for building the most popular cir- looking at the finish. But that high-polished, satin-like surface is not insulators,

panel), binding post panels, knobs, the new Radion built-in horn. cuits — mailed for ten cents. Mail coupon today. etc.— also

AMERICAN HARD RUBBER COMPANY Dept, F3. 11 Mercer St., New York City Chicago Office: Conway Building Pacific Coast Agent: Goodyear Rubber Co., San Francisco—Portland RADION The Supreme Insulation © PANELS Dials, Sockets, Binding Post Panels, ete.

The cam turns continuously, but does |

AMERICAN HARD RUBBER COMPANY, |! Dept. F3, 11 Mercer St., New York City { Please send me your new booklet, “‘Building I Your Own Set,’’ for which I enclose 10 cents | (stamps or coin).

o & Class Rings and Pins = Largest Catalog Issued —FREE Samples loaned class officers. Prices $.20 to $8.00 each. No 4a order for class, society, club § ‘| emblems too large or too small. B\ Special designs made on re- 38 quest.

RADIO SETS—AUTO BODIES SEND FOR THE INTERNATIONAL CATALOG 07 <3 msaaimmaniies r net price list. Full line of ~ Radio Sets; and auto Betiss tee ords Wholesate big. money by ae : ne ect From 914 W. Ohio $t., Dept. 8, Chicago, Ill,

International Bedy Works,

The Midget “Five-in-One”’ Slide Rule isa ¢ Polymet- ric, Log- Log. Binary, Add and Sub- tract Slide Rule, It will instantly add, subtract, multiply and divide any com- bination of whole numbers, fractions, mixed numbers and decimals. Gives Reuer also Logs, Sines and Tangents. Made of aluminum with scales on white celluloid. Size 4 in. Ap- proved and adopted by colleges. Price with Instructions, $1.50. Lea 50c extra. Sent C.O.D. if desired. Cat- alogue Free. GILSON SLIDE RUL

(Patented 1-17-22) CO.. Niles, Mich.

RECOVER IT $3.85 YOURSELF AND OUP . Make your car look like Custom Made newandsave abig labor bill. We have been making top recoverings, side curtains and seat covers for 15 years. We have patterns for all makes, no model too old forus. Easy to apply, simpleinstructicns given. Write for our big money saving catalogue with samples. THE LIBERTY TOP & TIRE COMPANY, Dept. E-8, Cincinnati, Ohio

© This seal on a radio or tool advertisement signifies

the approval of the INSTITUTE OF STANDARDS. See page 33.

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een Seeeennanae eoeee Senag -e “mae POPULAR SCIENCE MONTHLY ~gesumemeee =D) eheeheldatbabaaedbadhedadieheteatadbedateabadedeteabdee formance. table mounting. DON’T GAMBLE “1 in building your set by using inferior parts. You chance the loss of considerable time, money, and patience if the results aren’t satis- factory. Be certain! Use only Amsco parts. Made by men who really know their business, they lead the field in all around per- Amsco Parts necessary for those who construct their own include the Low Loss Condenser, a laboratory instrument designed for perfection in set building. Also the Amsco Rheostat, for perfect filament control with all types of :tubés and the Amsco Tube Socket with genuine Bakelite Base suitable for panel or At dealers everywhere. Free literature on request AMSCO PRODUCTS, Inc., Broome and Lafayette Sts., New York IS} March, 1925 $25.00 in PRIZE of book for details See top of page 10 in front 2 t is ; Ver- ning, 3 niet Dials. ‘ i a sim- ake loge'Pe oa They m oy a‘ tting e ratio atter 2 ple m Roy al n’ positive . The CHEMICAL FOUNDATION Incorporated in order to “advance chemical and allied science and industry in the United States,’”’ offers its book “Chemistry in Industry” Price $1.00 (the net printing and mailing cost) This book would ordinarily cost $5.00 but for three reasons: 1st, each of the twenty-one chapters is donated by its author, a recognized practical and scientific leader in his industry— 2d, the edition is very large—3d, The Chemical Foundation was chartered for the advancement of chemical and allied science and industry in the United States, therefore can seek no profit. The book covers these industries: Abrasives, Alcohol, Coal and Coke, Cotton, Electricity, Fertilizers, Gas, Glass, Iron and Steel, Leather, Non- Ferrous Metallurgy, Packing House, Paper and Pulp, Perfumes and Flav- ors, Petroleum, Photography, Resin, Rubber and Textiles. This book is unique in contents and price and being written in popular language appeals to factory owners, managers, superintendents, buyers, fore- men, workmen and to chemists and all students of Chemistry. If the 362 page clothbound illustrated book does not meet your needs, return it and receive your $1.00. Send $1.00 in check, money order or currency form to Dept. 9. The Chemical Foundation Incorporated 85 Beaver Street, New York Cutting Off Small Rods Rapidly in a Lathe Gort pins and other work made from small brass or steel stock can be cut off very rapidly in a lathe by the use of the simple device illustrated. Stock up to about 3/16 in. in diameter can be cut and either two or four cutters can be used, The cutters, which are tempered tool steel, are bolted to the faceplate. The faceplate it- self serves as a stop for the work. The height of the cutters from the base to the top or cutting edge is equal to the length of the pieces to be cut. A cast-iron angle block is bolted to the compound and fitted with a tool- steel bushing to suit the size of the rod to be cut. I have cut 3/16- in. rods with this device very quickly, By running the lathe at 500 revolutions a minute and having four cutters on the faceplate, I found it impossible to feed the rod fast enough to cut off four pieces at each revolution.—-CHARLES KUGLER, Philadelphia, Pa. H 5 | = fie (a The cutters and rod guide Protecting Small Pipes from Damage by Shop Trucks. TEAM and water pipes that run through factory floors sometimes are seriously damaged by hand-operated lift trucks or even electric shop trucks. In our shop we finally worked out the method illustrated for protecting the pipes and their expensive covering of magnesia and sheet-iron lagging. The protector also keeps the mop water from following down the pipe to the next floor, provided the protector is painted with white lead when put down. A 1-in. pipe and its covering of 85- per-cent magnesia measures about 214% in. To makea protector for it, take a piece of 24- in. pipe 14 in. long and have it cut in two on the planer with as narrow 4a tool as possible. Cut with a cutting torch out of 14-in. boiler plate a flange that will fit the outside diameter of the pipe and be about 6 in. in outside diameter. Cut the flange in two on the planer or milling machine. The flange and the four ears, which are approximately 14 by 114 by 114 in., are welded on and then the drilling is done. On pipes close to the wall one-half a protector will serve if long lag bolts are used, each with 2 nuts, 1 on either side of 23" PIPE) S (SPLIT) Fs Two types of pipe guards eS he the ear.—A. J. —

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Better Shop Methods rY OO OG O e O G 0) O O O D 0 t O DO D DO O O 0 U 0 O O b d dia 0 O 0 0 O CG O 0 t 0 pe t r) 0 O00 O WO O O O 0 O d 0 % eq O D OV a 0D ° 0 0 9 d a d ping G O O POOd D 0 O DO p O0aa ped O ‘ OQ 5 on a D ; ODS V O n DTODv 0 ‘ 0 0 O DO O QQ 0 g JODS O e d p 2 0 ae 0 0 PTOO A e e pea O O O 0 0 t) 0 O eC 0 a 0 e tapie loose

oug O v D pped lig v d D d d V O Ds d dep 0 e - ’ G e WO apped on one a to d 0 O on Oo d Oo f0 0 g SUuld Fuld ¢ ed co § D a d p a p DIVO g DO!t p g oug 0 he Dolt v 3 0 C 0D RB is) 0 O

Ca see sss emenan sen Co en AD Sy © What a whale of a difterence Just a few cents make

"tin liso | How to Build mers regen reg: CLTRADZNE x MODEL L-2 ; 5 to entors as to 32 page illustrated book with de- ons ec e e 2 tailed instructions on drilling, wiring, o address us 2 g e : e 2 assembling and operating Model L-2 : >< 9 DHE Ultradyne Receiver. Latest authentic edition by R. E. Lacault, A.M.I.R.E., inventor of the Ultradyne, the most selective receiver known. Write for descriptive circular. err - angie LUDEN S couchioxors THE famous Lupen Menthol Formula gives $7.9 Becnee St., N. ¥. quick relief to the Trouble Zone — your nose and throat. 5¢.

eR

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WuRLIIZER Couldn’t Play a Note— Now Makes +100” a week “Bill Carola” Land Read Bill Carola’s story in his own words— **When I sent for your catalog, I wanted a Tenor Banjo, but I hesitated a long time as I aidn’t know a note of music. I finally decided to try it a week, as you offered, and at the end of that time I found I could pick a few notes. Then i started the correspondence course you furnished, and in seven months, even before the final payments on.the Banjo were due, I had taken my place in a professional orchestra. Now I am making $100 a week, three times what I made as a clerk, Two of my friends made money with their instru- ments after five months practice, one a drummer and the other a Panapnoaist, and neither could play a note when he started. I ih everybody knew how easy it is—anyone who can whistle a tune can learn to play a musical instrument.” Bill Carola New Offer Learning to Pla atin FRE We now farnish | with every in- strumenta Free Scholarship Certificate. This scholarship entitles you to free tuition in one of the foremost correspondence schools of music in the country. Whether you want to learn to paw for profit or only | | for pleasure, this Free Scholar- . ship will make it surprisingly if easy for you. Free Trial Easy Payments You may have any Wurlitzer in- strument for a week’s free tr in yourown home. No obligation tobe . Payments are arranged in smali monthly sums, a fewcents a | day will pay for your instrument. Warlitzer instruments are the re- sult of 200 year’s experience in musical instrument building. Famous for ~) quality, rich Used lin the finest bands orchestras throughout the world. Free Book Illustrates and describes every known musical instrument—over 3000 articles. Special offers on complete outfits. Special prices direct to you, e also give you our Free Trial, Easy Payment plan an Scholar- d al Free ship ne obligation. Send Coupon Tod udolph Wurlitzer Co., 1783 The Redon ttre ie. Walch Ive, Cease 120 W. 42nd St. New Yerk 250 Stockton Francisce our Free Book on Musical Instruments. ona voue teen Trial, Easy Payment plan and Free Scholarship offer. No obligation. Name iste ne RII ova on no noc concn cocecncsncecconccncencessecsoce a instrument seo (State instrument in which you are interested) “9 Ee ——_ POPULAR SCIENCE MONTHLY Fixture U Finishing Curved Pipe By James A. Horton ECENTLY I saw an method of machining the inside of a curved pipe such as might be used in a cash register system. The radius of the curve is about 4 ft. A milling attachment is used on the planer in. connection with a _ special attachment for holding the pipe. A bracket is bolted firmly to the bed of the planer, as shown, and carries a stud that is a distance from the center line of the cutter shaft equal to the radius of the MILLING CUTTER PLATEN \ BRACKET BOLTED TO PLANER BED WORKeHOLDIN FIXTURE STUD AT RADIUS CENTER After one-half is finished, the pipe is re- versed on the fixture to complete the work center of the pipe. On this stud is pivoted a fixture for holding the work. It is operated by a T-head pin inserted in the planer bed loosely, but nevertheless a good fit. This moves the fixture when work is being done, but the fixture itself is supported by the planer table. The fixture is so constructed as to hold the pipe absolutely solid, and is so accu- rate that the pipe may be reversed, as the milling cutter goes only halfway through at the first operation. To insure the necessary accuracy, the ends of the sec- | tion and also the periphery of the flanges are finished in advance. Stand Safeguards Indicator IAL indicators have so much hard usage that a substantial stand is one of their most necessary ac- companiments. The stand illus- trated is firm and rigid and allows the indicator to be set at any angle desired. The base is cast iron, tapped to Dial indicator stand take the 14-in. vertical rod, which is made | of cold rolled steel, 14 in. long. The in- dicator rod is 12 in. long, of 34-in. cold- rolled steel. The clamp block is cold- rolled or machinery steel. One knurled thumb-nut serves to bind both rods. The clamping block can be set up tightly enough to prevent slipping in any direction and still allow a slight movement until the exact setting is made; then it is set firmly. interesting | March, 1925 ¢ Squab Book FREE Squabs selling at highest price: Greatest market for 20 oy / ried Known, breeding them. Raised in one month. 4 ship everywhere our famous breeding st and supplies. Established 24 ock Write now for big illustrated free eee How to Make Money Breedin, book | PLYMOUTH ROCK Souag ‘616 H St., Melrose wie At 60, Etter t Teading you ay ence, politics, travely fan, fash snows question box, books, health—entertainment today for this big paper on trial 1S were se ys for oom eterna) aper ontria weeks or $1 fori PATHFINDER, ington wea 559 Langdon Sta., Washington, D LASS OS¢ PING BUY DIRECT FROM THE MAKER CATALOG FREE \} Either pin shown made with any 3 letters and 2 figures. 1 of 2 colors enamel, Silver plate 25¢ ea. $2.50 doz. Sterling silver. 40¢ ea.. $4.00 doz. BASTIAN BROS. CO. 591 Bastian Bidg., Rochester, N. Y. 3214 4G, Motorcycle Bargains SAVE 25% to 65% on Slightly. Used and_ Rebuilt Motorcycles, Ace, Indian, Excelsior, Harley-Davidson, Cleveland, Side ars, Johnson Motor Wheels, Evans ce | * . ulletin an aed y &p Money Saving Message, listing ‘ ~ a a hundreds of bargains in used, rebuilt and new machines, supplies, accessories, etc. MERICAN MOTOR CYCLE CO. Dept. 328 2047 W. Chicago Ave. CHICAGO AUTOMOBILE MAKES 27 MILES ON AIR An automobile goes 27 miles on air by using an automatic device which was installed in less than 5 minutes. The automobile was making 30 miles on a gallon of gasoline but after this remarkable inven- tion was installed, it made better than 57. The in- ventor, Mr. J. A. Stransky, 135 Eleventh Street, Pukwana, South Dakota, wants agents and is willing to send a sample at his own risk. Write him today.—Adv. PRINT YOUROWN Cards, stationery, circulars, labels,. book,maga- ron } Zine, paper. PRESSES, $12 up, Card and Paper ghee? Cutters $3 up. Get more printing at half old cost, les Need MONEY? ake IN CS of ONE Make it printing for others, Big Profits, ASSES No experience required; all easy with our printed rules supplied with every press. YOUNG MEN and BOYS here is a chance for you to have a business of your own. Write for catalog presses, cutters, type, cards, paper, ink. THE PRESS CO., N-33, Meriden, Connecticut DEAFNESS IS MISERY I know because I was Deaf and had Head Noises for over 30 years. My invisible Anti- septic Ear Drums restored my _ hearing stopped Head Noises, and will do {t for you. They are Tiny Megaphones. Cannot be seen when worn. Effective when Deafness is caused by Catarrh or by Perforated, Partially or Wholly Destroyed Natural Drums. Easy to put in, easy to take out. Are ‘‘Unseen Comforts.” Inex- pensive. Write for Booklet and my sworn etatement of how I recovered my hearing. A. 0. LEONARD, Suite 301, 70 5th Ave., New York is OGRAF ie Protect your tools from theft. Write any name, engrave any design on tools and metal with electricity like writing on paper with hs : o- or pencil. Complete outfit Cs 3.50. prepaid anywhere. Interest- ing descriptive circulars free. Write 0-day. ents wanted, Power Cycles, Bicycles. Free Bargain Direct from our factory to wearer. Easily sold. Over one million sat- isfied wearers. No capital or experience required. Largesteadyincome. Many earn $100. to $150. weekly. ‘Territory now being allotted. Write For Free Samples. l MADISON SHIRT M’F°RS, 505 Broadway, New Yous IS} This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. - ec ep est RAN —

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using an s than 5 miles on le inven- The in- i Street, and is Write

| Expansive Chucking Arbor for | Holding Gear Blanks | HIS arbor is designed for turning and | T cutting and grinding gear blanks ‘and similar work in the lathe, milling | machine, grinder or gear-cutting machine. | mt is made of one piece of tool steel, A, hardened and ground on the outside to fit | the hole in the work, except that .005 in. | | jg allowed for expansion. A draw bolt, i 6 SLOTS~§' SAW ® DRILL Sem jp b- ne 4 | p= \

Willa ills Te i 10° INCLUDED 10° REAMER— ;ANGLE RAW BOLT, 7 wT % | ae * C 7B How the arbor is made and the special reamer for finishing the draw-bolt seat

B, bears against a tapered seat and ex- tends through the front end of the arbor. The arbor is drilled clear through and a special reamer, C, is made to finish the tapered seat. Six longitudinal slots in. wide are cut after.the holes shown are drilled.

Floor Stand for Hand Reamer Saves Machinist’s Time EAMED holes in automatic and turret machine work often are sized with a hand reamer to insure accu- racy. In most cases this operation can be done by the operator while his machine is running, provided he does not have to leave the machine to use a vise or other tool to hold the work for reaming. The floor stand shown below, which is a simple casting made in two pieces, is bolted to the floor in the most convenient position for the machine operator. The hand reamer is held in the V-block, ‘part of which is integral with the main

WINONUTS

99 / BRASS LINERS 2°SQ SS 59, HARD MAPLE CORNERS ROUND CAST-IRON AND SMOOTH PEDESTAL

* $ be. Bo The reamer stand and wooden clamp for holding the work to be reamed casting, and the other half is movable to take reamers of different sizes. The square shank of the reamer is clamped in a vertical. position by tightening two cap screws. As soon as the operator removes a plece from the machine, he clamps it in wooden clamps, which give a good lever- age for turning the piece on the hand reamer. Straight bushings or small irregular castings may be held conveniently and reamed rapidly with this outfit. Operated, the operator starts another plece before reaming the preceding one, 80 as not to lose any production time.— H.L. W.

|

If the | Machine is semi-automatic or hand- | POPULAR SCIENCE MONTHLY

DUBILIER CONDENSERS Important Links between the Shenandoah and Land! OMMUNICATION with land—under all conditions— at all times—this was the imperative need of the Shenandoah on its experimental flight across the continent. Impressed with this need, army and navy engineers equipped both transmitting and receiving sets with Dubilier mica condensers—not specially designed condensers, but the regular standard product. Only complete confidence in the supreme reliability and efficiency of Dubilier con- densers can explain their use in this important and daring adventure. ‘ Dubilier

CONDENSER AND RADIO CORPORATION

Lightness combined with unusual strength ZB

IRTY years’ experience in canoe building lie back of every Carleton Canoe. Year by year we have im- proved and perfected them. In the 1925 Carleton Canoe, we believe that we have achieved the ultimate in canoe manufacture. The Carleton is a light canoe. It is beautifully balanced and handles easily under heavy loads. Carleton Canoes are very low in price too. Our new illustrated catalog gives prices and complete information. Write today for your free copy. Tue Car.eton Canoz Co., 73 First Street, Old Town, Maine, U.S. A. ARLETON CANOES

LO! Ss Ee

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

¥ is? é ee Save $1000 When You Build LITTLE mistakes often run into a $1,000 or more. Keith’s remarkable new book and Keith’s Magazine show how to avoid these costly errors—also many short cuts that save money. This amazing book, ‘Beautiful Homes,’”’ contains two hundred actually tested plans. Shows all types of houses,—Stucco, Brick, Tile or Frame. Gives fashionable new ideas on Interior Decoration. With this De Luxe Plan Book you receive a year’s sub- scription to Keith's Magazine, the recognized authority on home building for twenty-five years. Just send your name and address and pay postman only $3 plus a few cents postage upon arrival. Write at once. KEITH CORPORATION, ARCHITECTS 100 N. 7th St. inneapolis, Minn. ——— A cn Keith Corporation, Architects, 100 N. 7th St., Dept. 19-C Minneapolis, Minn. Send me ‘‘Beautiful Homes’’ De Luxe Edition and a year’s subscription to Keith’s Magazine. I will pay the postman only $3 plus a few cents postage.

INGMNO: con vc cteccdc sets se <e eee eabeds seen nme po ee eens ire See J eee Se. State.... +? If you send $3 with order, book will be sent postage prepaid.

LS BOA ATER

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EARLE E. LIEDERMAN The Muscle Builder How Long Do You Expect to Live? Make your own answer. It’s up to you. I know you might be hit on the head with a brick or be pushed off the end of a dock. But barring accidents, what then? If you take care of an automobile it will last for years— abuse it and you might as well cash it in ‘aa the first year. This is just as true of your own b IF YOU DO—YOU DIE Go ahead with your careless living if you want. Eat and drink what you like. Abuse your body—it’s yours to do with as you please. You may think you're having a good time. But are you? You get up in the morning feeling half dead. You drag yourself through the day. Don’t you know your body is clogging up with poison? Don’t you know your lungs are starving for oxygen? Don’t you realize your inner celis are breaking down and you are not doing a thing to replenish them? You're dying, man—and you don’t know it. I ADD YEARS TO YOUR LIFE You need exercise. You must have it. Tie your arm to your side and it will wither away—but use your muscles and you have more muscle to use. Every vital organ is completely surrounded with muscles which make those organs function. Exercise and you strengthen the organ itself. You wear down the dead tissue. The white corpuscles of your blood carry them off and the red corpuscles supply new healthy tissue. You drive death and. disease out and bring new life to a worn down and famished body. YOU NEED A TEACHER Just any kind of exercise won't do. I have had men come to me who were literally broken down from work in factory or mill. With scientific instruction I brought them back to strength and power. y system has been tried and proven. It never fails. Some claim, eh? Well, it’s true. I don’t care what your present condition is. I'll knock those microbes higher than a cocked hat. I'll shoot you ful! of life and vitality. And muscle? That’s my middle name. In three months’ I'll build up every muscle in your body. I'll broaden out those shoulders and deepen your chest. Every breath will bring deep loads of oxygen to your lungs, purifying your blood and shooting a thrill throughout your entire system. I'll brighten your eyes and clear your skin. I'll make you so full of pep you will feel like shouting out to the world: ‘I’m a man and I can prove it.” And remember, fellows, I don’t just promise these things—I guarantee them. Do you doubt me? Make me prove it. That’s what I like, because I know I can do it. Come on, then. Snap into it. Are you ready? Let’s go. Send for new 64-page book eecuLAS DEVELOPMENT’? It is FREE It contains forty-five full page photographs of myself and many of my prize winning pupils. Some of these came to me as pitiful weaklings, imploring me to help them. Look them over now, and you will marvel at their present physiques. This book will prove an impetus and a real inspiration to you. It will literally thrill you. All I ask is 10 cents to cover the cost of wrapping and mailing. This will not obligate you at all, but for the sake of your future health and happiness, do not put it off. Send today, right now, before you turn this page. EARLE E. LIEDERMAN Dept. 1303, 305 Broadway, New York City EARLE E. LIEDERMAN Dept. 1303, 305 Broadway, New York City. Dear Sir:—I enclose herewith 10 cents, for which you are to send me, withont any obligation on my part what- ever, a copy of your latest ment.” book, ‘‘Muscular Develop- (Please write or print plainly.) POPULAR SCIENCE MONTHLY

cei ceanenat Bench Made with Legs of Angle Iron FPREQUENTLY the garage owner or small-shop man wishes to make a few good bench legs. For this he can use 114- or 2-in. angle iron, without any ma- chining except drilling and either sawing or careful cutting with an acetylene torch. The height and width of the legs de- pend upon the builder. For a bench 10 ft. long, three legs will be sufficient. The pieces of angle iron are cut out in pairs, as shown, and all joints are fastened with 3¢-in. rivets or welded, the latter being preferable. The upward projection at the rear is for a %%-in. back board and should be 6 in. high. For the top of the bench my preference is for a 2-in. maple plank, ea on both

Stock 1!4- or 2-in. angle irons are welded or riveted together to form rigid bench legs sides and boltéd down with 3-in.-long carriage bolts. The holes are plugged tightly with spruce turned to fit. The backboard is put on with 14-in. carriage bolts and nailed at intervals to the % by 2 in. piece. A piece 1% by 2 in., and as long as neces- sary,is placed against the front of the back board and a similar piece is nailed against the back of the maple plank. The space between the back edge of the maple plank and the back board is filled with 11%-in. matched pine of the first grade, or the same thickness of the second grade maple flooring, which should be tongued and grooved, laid tight by crossways of the bench, and toe-nailed. For the bottom shelf, use 2 by 4 in. spruce supports and fill in with 7-in. spruce crossways of the bench nailed with eightpenny cement-coated nails. The bench top should be planed and finished with orange shellac.—A. S. JAMIESON.

Lapping a Micrometer Spindle A MICROMETER spindle, through long continued use, wears on the end so that it is not square with the anvil. To square up the end, make a fiber bush- ing to fit snugly over the spindle. The hole should be reamed and the bushing faced square. Remove the spindle from the micrometer, place it in the bushing, and lap the end until square, using a

cast-iron lap with flour emery and gasoline.

4 MOTIONS used in playing the fascinating awaiian Gui- tar. Our native hye Hawalian instrue- mi ors teach you to m quickly. Pictures an Everything explained ¢ PLAY IN HALF After you get the 4 easy mo. ee. yon Son ® play harm chords wi h very little pe 40,000 students have learned’ r play in this easy, pleasant way EASY LES§ ONS The 52 printed lessons with a

p=) ical knowledge _nece: learn to Cy Pom kind of muse, = pay as you pia: FREE GUITAR ‘© new students we give this full size, hi strument free of nthe! is seni = atonce without red tape or delay. WRIT Ez AT ONC E Send your n: at once = let w tell you ail about the 52 eas: y lessons and the free guitar. Vou tun have, every. a pogain- an as put it off. A ost card wi cial offer and easy te = hg ba First Hawaiian Conseres . of Music, Inc. 233 Broadway (Woolworth Dept, 46, New York, N Bide.

Special courses on Vio- lin, Tenor-Banjo, Ban- jo-Ukulele and Ukulele

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

Mason, Fenwick & Lawrence Patent and Trade-Mark Lawyers Washington, D.C. :: New York :: Chicago

Established over 60 years. Write us,

References: National Confectioners’ Association, aes National Canners’ Association, Washington, D.C.; Life Savers, Inc., Port Chester, N. Y.; Bon Ami Go. and U. 8. Cigar Co., New York City;’ Her shey Chocolate Co., Hershey, ’Pa.; .; Stephen F. Whit- man & Son, Philadelphia, Pa., and many others,

Inventions protected. Trade marks registered, Big Value for 10 Cts, 6 Songs, words and music; 25 Pic tures Pretty Girls; 40 Ways to Make Money; 1 Joke Book; 1 Book on Love; agic Book; 1 Book Letter Writ- ing; 1 Dream Book and Fortune Teller; 1 Cook Book; 1 Base Ball Book, gives rules for games; 1 Toy Maker Book, Language of Flowers; 1 Morse Telegraph Alphabet; 12 Chemical Experiments; Magic Table; Great North Pole Game; Conundrums; 3 Puzzles; 12 Games; 30 Verses for Autograph Albums. All the above by mail for 10 cts. and 2 ets. postage. ROYAL SALES CO.., Desk 215, Norwalk, Conn.

: 01 fo Wales a rik ‘Standard makes often at less than one-third Be fl \ regular price! All sizes +—A and styles. Every machine guaranteed : A-1 condition. Rebuilt by experts. SOLD ON INSTALLMENTS You can bu uy 8 a reguley | _ machine for as low as down. pay big ag Hundreds of * nown_ firms customers. Write for FREE list | a and bargain prices that save money. Do it NOW. RELIABLE ADDING B ACHING CORP. Dept. 103 CHICAGO, IU Uke THIS ENGINE FREE 70) AW AA ate) (= Adlevalea SEND NO MONEY trv thi ye to try rat a0 S Engine makes payments. i f im fore shigges, Use i $0.22 HOP. One ne year sae. BY EBOOK rnginen taiinwhy thou 95 caginee; wit, AFTER TRIAL ines; 3e%; start canter, and economical to run. Send your n: 1951 C King Street, Ottawa, Kansts 1951-C Magee Bldg. ,Pittsburgh Pa.

Your is all r for e

OTTAWA MFG. CO., osx See page 33.

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ite us, iation, ington, 1925 POPULAR SCIENCE MONTHLY 159 - 4 MARKS-COPYRIGHTS. S PROTECT YOUR INVENTION rc ANY NEW article, machine, design or improvement thereof, or any com- bination of parts or improvements in any known article which increases its efficiency or usefulness, may be patented, if it involves invention. If You Have Any New Ideas which you feel are useful, practical and novel, take prompt action to protect your rights. If you have invented any new machine or new combination of parts or improvement, or any new design or process, SEND DRAWING, MODEL OR DESCRIPTION of it for information as to procedure to secure protection. ae , iy ‘ DRAFTING and SPECIFICATION ROOM of CLARENCE A. O’BRIEN, Registered Patent Lawyer, Washington, D. C. } All communications are held in strict confidence. My personal, careful and thorough attention is given to each case. I offer you efficient, reliable and (it, prompt service—based upon practical experience. Highest references. = ry th NO CHARGE FOR ABOVE INFORMATION Write today for free books, ‘‘How to Obtain a Patent’’ and ‘‘Inven- tion and Industry’’ and blank form ‘‘Record of Invention.”’ These books will give you valuable information, and they may save you much time and effort. Send for them now. My practice is devoted exclusively: to Sy United States and Foreign Patents and Trade Marks. Write me freely, frankly and with full pain in it is very probable that I can help you. These Books Free Use the Coupon attached, and immediately upon its receipt I shall send you the form Record of Invention to be returned to me with drawing, description or model of your idea; promptly upon re- ceiving your idea I shall write you as to procedure and costs. CLARENCE A. O’BRIEN REGISTERED PATENT LAWYER Member of Bar of Court of Appeals, District of Columbia, United States Court of Claims; Supreme Court of i | United States, Supreme Court District of Columbia. fn} ---------------- FREE COUPON --- | CLARENCE A. O’BRIEN, REGISTERED PATENT LAWYER 889C Security Savings and Commercial Bank Building Directly across Street from U.S. Patent Office, Washington, D. C. Please send me your free books, ‘‘How to Obtain a Patent” and ‘‘Invention and Industry” and blank form, ‘Record of Invention,”’ without any obligation on my part. See page 33.

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as ace ee POPULAR SCIENCE MONTHLY PATENTS TRADE-MARKS DESIGNS FOREIGN PATENTS MUNN @ CO’... - PATENT ATTORNEYS Associated since 1846 with the Scientific American 683 WOOLWORTH BUILDING New York City © 411 TOWER BUILDING Chicago, Ill. 522 SCIENTIFIC AMERICAN BLDG. Washington, D. C. 364 HOBART BUILDING ' > San Francisco, Cal. 219 VAN NUYS BUILDING Los Angeles, Cal. -—$_—po—_1 Books and Information on Patents and Trade Marks By Request. Hl Associates in All Foreign Countries. $25.00 in Prizes See top of page 8 in front of book for full details The Question of B’ Battery Current Solved with the |: BG Kellogg Trans-B-Former 5 MAKE and keep your cellar walls, floor and boiler and drain pits thoroughly dry by fill- ing the cracks and coat- ing the surface with Smooth-On No. 7, the only practical water- proofing material that can be effectively ap- plied from inside and bonds —— os = or dry surface. xcel- ; lent also for patching FREE BOOK © concrete floors, water- ‘ proofing garage, stable and oo r . floors, brick walls, cisterns, septic tanks, ‘THE Kellogg Trans-B-Former water troughs, fountains, fish ponds, furnishes the necessarv plate || swimming pools, manure pits, etc. volta f a di A f Requires about 25 lb, Smooth-On per ges tor your radio set, rom |{ 100.sq. ft. of surface and you can do the your 110 A C, 60 cycle, electric work yourself. light socket without any inter- ference. NT Sold in 5 and 10-lb. cans 25; 50 and 100-lb. kegs This unvarying current is SMOOTH-ON MFG. CO. Dept. 60 574 Communipaw Avenue JERSEY CITY, N. J. furnished at less than one- fifth cent per hour. Throw away your “B” batteries and’ install. a ‘Trans-B-Former’ and your set will operate at maxi- MS 2 E- mum efficiency constantly. * 3 a The Kellogg Trans-B-Former will: : (ek Improve reception educe operating cost to a minimum Add to the appearance of your set Developed, perfected and guar- : anteéd by the Kellogg Switch- board and Supply Company. At Your Dealers NEN: 6 ore HESS av oh eS 6 voles vs KELLOGG SWITCHBOARD & SUPPLY COMPANY 1066 Adams Street Chicago, Ill. March, 1995 ‘ber of farms in the United States to be How Electricity May Solve the Farmer’s Problem (Continued from page 37) According to the Rural Electric Service Committee of the Nationg) Electric Light Association, there were last May, 166,000 farms connected with light- and power-station distribution lines The most recent estimates of the number of individual power and light sets range from 240,000 to between 300,000 and 400,000. In 1920, according to the Censiis of that year, 452,620 American farms had either gas or electric service. Of these it is estimated about 348,000 had electri¢ service. a ‘THs is a rather impressive total when considered by itself. It is not impres- sive, however, when you consider that the same census showed the aggregate num- 6,448,343. One essential point is being kept. in mind by the Minnesota committee which says, in describing the Red Wing ex. periment: “The problem of reaching the farmer with electric service is not one of sentiment, and it is not an engineering problem, for if the electrical engineer were given an inexhaustible purse, he could readily extend lines to every farm in America. The problem is really a financial one and the main purpose of this entire project is to: determine whether electric service can be extended to the farm ona basis of charges acceptable to both farmer and power company.”’ It will be noted that stress is laid on the distribution phase of supplying service. This is based on the idea that power is to be furnished from a central light and power station, as it is at Red Wing, rather than by individual light and power sets. The latter serve a very distinct purpose. They make it possible for the farm situated beyond light- and power-station distribution lines to have the advantages of electricity for lighting, for operating household electrical appliances, for pump- ing, and some of the lighter kinds of farm work. There are farms so remote from present or prospective light- and power- station lines that it will be years, if ever— barring the finding of new methods of distribution—before light- and power- station service will be available to them. To all such, the individual set is a boon. However, light- and power-station |. service offers a distinct advantage, not only in convenience, but in offering the farmer a practically unlimited supply of power—which the individual set does not. In any broad consideration of the problem, the real electrification of the farms depends on central station service. HERE are two important factors in the distribution problem that have already been touched upon—the small number of farms to the mile and the small amount of power used by such farms as have been electrified. The farms average, as stated, but few to the mile, whereas in the cities a mile of distribution line serves from 50 to 200 (Continued on page 162) IS} This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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hen res- the | um- > be t. in hich ex- ‘mer of ring were ould n in ncial ntire ctric ona rmer d on lying that ntral Red t and pose. farm ation tages ating juMp- farm from ower- ver— ds of ,ower- them. on. tation |. 2, not ig the ply of »§ not. f =the of the arvice. ‘ors in ; have small d the > such The to the ile of -o 200 New York Office Suite 1007 Woolworth Bldg. Philadelphia, Pa., Suite 714-715 Liberty Bldg. Washington, D.C., Office Victor Bldg. POPULAR SCIENCE MONTHLY COPYRIGHTS OUR OFFER: Your first step ? Before disclosing an invention the inventor should write for our blank form \“*RECORD OF INVENTION.” This should be signed, witnessed and returned to us together with model or sketch and description of the in- vention for INSTRUCTIONS. NO CHARGE FOR THE ABOVE INFORMATION Our Four Books Mailed Free to Inventors Our Illustrated Guide Book HOW TO OBTAIN A PATENT Full instructions regarding U. S. Patents. Our Methods, Terms, and 100 Mechanical Movements illustrated and described. OUR TRADE MARK BOOK Shows value and necessity of Trade Mark Protection. Information regarding Trade Marks and unfair competition in trade. OUR FOREIGN BOOK We have Direct Agencies in Foreign Countries, and secure Foreign Patents in shortest time and at lowest cost. Progress of Invention Description of World’s Most Pressing Problems by Leading Scientists and Inventors TRADE-MARKS ALL COMMUNICATIONS AND DATA STRICTLY CONFIDENTIAL INTERFERENCE AND INFRINGEMENT SUITS PROSECUTED Private Office, Victor J. Evans, with View of Patent Office Through Window Eterlsetg oriasbetennenrstestechytestrotaieaterswentercrt- som ighest References Prompt_ Attention Reasonable Terms I VICTOR J. EVANS & CO., Patent Attorneys | I | Main Ofhces: 760-9th Street, N. W,, Washington, D, C, | Gentlemen: Please send me FREE OF CHARGE your 1! FREE I I I I books as described above. UN tencdnisaavese nenseen ss ebieanveresarhhotabonchens PCM EOOS 5. c cic le\cie @ieidais Wises Web enee RRM a ee Ceewneee ee tm | © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. Chicago, IIl., Office Suite.1114 Tacoma Bldg. ae aR RE Pittsburgh, Pa., Office i | Suite 514, Empire Bldg. (Paeeee Stites San Francisco, Cal., Office | Suite 1010 Hobart Bldg.

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ad $100 for One Good | Commercial Drawing | Become An Artist This Easy Way Thousands who never dreamed they could draw can now easily become artists. You, too — without any previous training—and no matter how little apparent talent you have —can now easily learn IlIlus- trating, Designing and Car- tooning through this amazingly easy method. You learn at home, yet your work receives the personal attention and criticism of one of America’s most successful artists. Many stu- dents actually sell enough work dur- ing their training to pay for it many times over. Big Money in Commercial Art Millions of dollars are being spent this year on advertising and story illustrations, commercial designs, and cartoons. And even more will be spent next year. Commercial art is a tremendous field—and a field where very big money is gladly paid anyone who can produce good art work. Adver- tisers, magazines, newspapers, printing houses, business concerns all need trained artists. Competent artists easily earn from $50 to far over $300 a week. And now you can easily enter this ‘‘world’s most fascina- ting, best paid business.” Mail Coupon for Free Book A new handsomely illustrated book has just been printed, which gives all the most up-to-date infor- mation on the thousands of wonderful opportunities in Commercial Art and shows how this startling new method easily enables you to enter this field. It tells about our students—their success—what they say—actual reproductions of their work—how they made big money while studying. This attractive book will be sent without cost or obligation. Send for it. Mail coupon now. Washington School of Art Room 243-C, 1115-15th St., N. W. | Washington, D. C. Washington School of Art Room 243C, 1115-15th St., N.W., Washington, D. C. Please send me without cost or obligation your new book on art, ‘‘New Easy Way to Become an Artist,’’ and details of your special offer. — RES ee ea POPULAR SCIENCE MONTHLY How Electricity May Solve the Farmer’s Problem (Continued from page 160) users. This inevitably makes it more expensive to serve the farms than the towns and cities. Distribution lines are expensive to con- struct. Costs vary, of course, and it is impossible to set down a definite figure that will apply to all sections of the country and all conditions. Nor is this the only item that must be considered. The rural line must bear its share of the general overhead. There are losses of energy in distribution. Before a single watt of power has been delivered to the farmer, a considerable expense has been incurred. There are meters to be read— an item proportionately much more ex- pensive in the country than in the city. The line must be kept in repair. S STATED, the cost of distribution would be relatively less important if the farmers used a greater amount of current. Therefore, one of the principal objects of the Red Wing experiment and others like it is to find how the farmer can profitably use a larger amount. The tentative rate set for customers on the Red Wing line was devised to invite a liberal use of power. It is divided into a service charge (which includes interest, depreciation, maintenance, taxes, book- keeping, meter reading, and core losses) and a charge for the power consumed. The service charge was tentatively set, on the basis of three customers to a mile, at $6.90 a month. The tentative rate for the first 30 kilowatt-hours of power consumed a month is five cents a kilowatt- hour; for all in excess, three cents. ‘** Applying this rate to actual consump- tion,’”’ says the committee, “it is found that electricity necessarily will have to be counted as a rather expensive luxury by the farmer who cares to use only a little of it. He is very much in the position of a farmer telephoning a store five miles away to send him a cake of yeast. Na- turally, the price of the cake of yeast, plus the delivery charges, would make it. a costly cake.” It will be seen that this schedule works out as follows: The farmer who uses only 20 kilowatt- hours of power a month pays a service charge of $6.90, plus $1 for power, making a total of $7.90, or at the rate of 39.5 cents a kilowatt-hour. If he uses 100 kilowatt-hours, he will pay the same service charge of $6.90 and $3.60 for power, a total of $10.50, or at the rate of 10.5 cents a kilowatt-hour. The total bill for a farmer using 300 kilowatt-hours would be $16.50, or at the rate of 5.5 cents a kilowatt-hour. 4S Nea suburban territory lying between cities and the surrounding farming districts, and the innumerable villages scattered all over the country, aid to some extent in giving electrical service to the rural sections. In cases where they offer a sufficient load to justify the extension of distribution lines, they bring ‘ais ser- vice nearer to the farms. (Continued on page 163) : ati AU SEND EOE al 1 DON’T LOSE YOUR RIGHTS TO PATENT PROTECTION Before disclosing your invention to anyone send for blank form ‘‘EVIDENCE OF Con. CEPTION”’ to be signed and witnessed, A sample form together with printed instructions will show youjust how to work up your eyj. dence and establish thesame before filing ap. plication for patent. As registered patent at- torneys we represent hundreds of inventors al] over the United States and_ Canada in the ad. vancement of inventions. Ourschedule of feeg # willbe found reasonable. The form “Evidenge of Conception,”’ sample, instructions relating to obtaining of patents and schedule of feeg —_ a request. Ask for them,—a post card will do. PATENTS ANDO en TRADE MARKS Registered Patent Attorneys 274 Ouray Bldg. WASHINGTON, D. C. Originators of forms “Evidence of Conception.” To the Man With an Idea I offer a most comprehensive, ex- perienced, efficient service for his prompt, legal protection and the development of his proposition. Send sketch, or model and description, for advice as to cost, search through prior United States patents, etc. Pre- liminary advice gladly furnished with- out charge. My experience and familiarity with various arts, frequently enable me to accurately advise clients as to prob- able patentability before they go to any expense. Booklet of valuable information and form for properly disclosing your idea, free on request. Write today. RICHARD B. OWEN Patent Lawyer 6 Owen Building, Washington,D.C, 41-D, Park Row New York City PATENTS » REGISTERED PATENT ATTORNEY SINCE 1905 , CHARLES W LOVETT Stcutity 6106 [YAN MASS. Ga SENO FOR FREE GOOKLET ype * J / SK 2> OSS M { PATENTS BOOKLET FREE HIGHEST PROMPTNESS ASSURED B Send drawing or model for examination and report as to patentability WATSON E. COLEMAN, Patent Lawyer 644 G Street N. W., Washington, D. C. REFERENCES EST R eS A rth Ses | * et he OS HF CSU CUS —- + Oo maa rt oO 2,08 @®. a oO ot ~ ert oo = Oo et of — = oo fF © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. TT TT A 1 4 oe ome

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March, 1925 How Electricity May Solve the Farmer’s Problem (Continued from page 162) Present study of farm electrification deals very largely, of course, with im- mediate possibilities. For example, among the subjects of experiment by the Agriculture Experiment Station of the Alabama Polytechnic Institute are the application of electric drive to grinding feed, sawing wood, pumping water, baling hay, milking, separating cream, churning, corn shelling, feed mixing, clipping ma- chines, grindstones, tool grinders, spray pumps, fertilizer mixers, limestone crush- ers, seed graders, seed cleaners, peanut pickers, ensilage cutters, incubators, brooders, egg candlers, and other de- vices, in addition to lighting and the operation of household devices. OMMUNITY industries that will be studied include creameries, sawmills, grist mills, syrup plants, cotton gins, meat-curing plants, threshers, hatcheries, ice-making plants, canneries, and other undertakings of the kind. Beyond these is the question of using electricity for plowing, harrowing, sowing, cultivating, and harvesting. It presents difficult problems. ‘But the experience of other countries would seem to prove that they are not insuperable. The future may show that electricity can be used on a commercial scale to promote plant growth. This offers highly interesting possibilities. Other uses, at present unknown, may be disclosed by research. If electricity does nothing more than effect a sensible check on the migration to the cities, it will have accomplished a great thing. Recent Publications Practical Radio, by James A. Moyer and John F. Wostrel. Up-to-date prac- tical information for the radio enthusiast and experimenter. Illustrated. McGraw- Hill Book Co. A Hand-Book of Solar Eclipses, by Isabel M. Lewis of the U. S. Naval Observatory. A comprehensive, popular discussion of a most fascinating subject. Illustrated. Duffield & Co. Hudson Maxim—Reminiscences and Comments, by Clifton Johnson. An entertaining biography of a picturesque leader of the world of invention. Illus- trated. Doubleday, Page & Co. The Boys’ Book of the Earth, by Sidney Aylmer Small. Geology made wonder- fully interesting for boys or for any one else who enjoys the presentation of scientific fact in lively, non-technical language. Illustrated. E. P. Dutton & Co. Electrical Amusements and Experiments, by C. R. Gibson, F.R.S.E. Interesting and amusing tricks, illusions, and experi- ments that can be performed with homemade electrical apparatus. Illus- trated. J. B. Lippincott Company. Fungi and Human Affairs, by W. A. McCubbin. The influence of fungi and bacteria on man’s activities, with special reference to plant diseases. Illustrated. World Book Company. POPULAR SCIENCE MONTHLY « eats, 163 odel ‘Tungar batterie = 4 re On the back of the Tungar, there are three terminals. Slip the wire into one and charge your radio “A” battery, 2 or 4 volt size. Use the second to charge your radio “B” batiery, 24 to 96 volt size. Or the third will charge a The Tungar is a G-E product, developed in the great Research Laboratories of Gen- eral Electric. The New Model Tun- gar charges radio A and B batteries, and auto batteries. Two ampere size (East of the Rockies) $18.00 The Tungar is also available in five am- pere size (East of the Rockies) . . $28.00 60 cycles—110 volts GENERAL ELECTRIC 6 volt “A” battery or 6 to 12 volt auto battery. Just clip on the Tungar, and plug it into any electric outlet in the house or garage. Then leave it overnight to charge while you sleep, Very simple. Tungar—a registered trademark—is found only on the genuine. Look forit on the name plate. Merchandise Department © General Electric Company Bridgeport, Conn. RRR TERI our terms, methods, etc. your invention for our Instruc- tions. No Charge for the Above Information. RANDOLPH & CO. Dept.130, Washington, D.C. NVENTORS \ca07G2 YOUR IDEAS Send for our Guide Book, HOW TO GET A PATENT, and Evidence of Invention Blank, sent Free on request. Tells Send model or sketch and description of "alae ~~ Oe ee ee ee eee ee ee OS eee eS SOSH R OSES EOEH OHO ETE EEE ee ereee sere reecesecceeseseeemsMibes ceeseseseses © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. ase ee ce

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I pay men $100.00 a week and up by my plan which I want to send you at once. Be your own boss, work where and when you like. You can | do fine even without previous f experience. Biggest values— { positively sell on sight. Profits in Advance! My plan pays biggest profits and commissions in this line, all aes in advance, we attend to elivering ordersandcollections, Sell Tailoring Astonishing values get orders easy when you show gamples of our tailored toorder, all wool, lin and _ o’coats—one price$31. 50. ‘ a 7 Our oe a | you take orders a | PREE * , Thisbig,finesampleout- "|, fit furnished free, con- tains 100 all wool bie gamples, allone price 31.60, fine colored ey. supplies, tape, _ All in class: W. Z. GIBSON, Inc., 161 West Harrison St., o fil, Pte C-521 Please send me your plan for $100 a week and up, also FREE outfit and sales manual. __ State “ WHITING -ADAMS ~ The Household 1} Duty -word meanin iS Good Brushes WHITING-ADAMS BRUSHES JOHN L. WHITING-J. 1, ADAMS GO., Boston, U. Brush Manufacturers for Over 116 Years and the Largestin the World POPULAR SCIENCE MONTHLY Why Everybody Is Solving Arithmetic of Electricity A practical treatise on electrical calculations of all kinds reduced to a series of rules. $1.50 Postpaid. POPULAR SCIENCE MONTHLY 250 Fourth Avenue New York Cross-Word Puzzles (Continued from page 38) of cross words traveled. Not to know of them, not to have worked them, soon stamped one as being behind the times. That, briefly, is the story of the growth of the fad. However, to know why the cross-word puzzle has come does not explain the ex- traordinarily violent, even unprecedented hold it has taken on the popular fancy. Why have the people who escaped Chinese games, radio, bridge, golf, and even the movies, succumbed at last to a popular fad? Why is it that the solving of puz- zles, which has been practiced to a greater or less extent since the dawn of history, should have waited until the years 1924- 25 before becoming a universal pastime? 6 Keon second question possibly is the more easily answered. Cross-word puzzles never could have flourished in the past, for the reason that the level of gen- eral education, even a score of years ago, was much lower than at present. Another reason for their success is that cross-word puzzles are almost the first fad of history the practice of which costs virtually nothing and requires the de- the acquisition of no unusual equipment, the learning of norules. With a lead pen- cil, and possibly a pocket dictionary to aid in getting over the hard spots, any one who can write and who possesses the working vocabulary of the average news- paper reader is fully equipped to tackle any but the most difficult cross-word puz- zles—and to solve them. To the psychologist, however, readily occurs an even more potent reason for the amazing popularity of this newest fad. Successfully working out cross-word puzzles, more than any similar amuse- ment that the writers can recall, satisfies a long list of the fundamental desires of human kind. Social distinction, sex, imi- tation, group loyalty, cooperation, com- petition, pleasure, play, amusement, humor, curiosity, activity, and con- structiveness—all of these ingrained, in- stinctive wants of man are satisfied merely by printing letters in the proper squares. BL OCTAL distinction certainly is the reward of one who most skilfully and most quickly solves a difficult puzzle on which other puzzle addicts are working. The puzzles appeal to the sex instinct in that they supply a new reason for social gatherings, of young people particularly. The puzzles never would have attained their present popularity were it not for the imitative appeal that caused one person to start doing puzzles because his neighbor was doing them. Group loyalty and cooperation are manifested strikingly in the bonds that join puzzle fans, no matter how widely their other interests may differ. Any one who has ever worked a puzzle will admit that it satisfies the desire for competition, play, pleasure, and amuse- ment. Humor finds its way into the game in many ways—sometimes in the far- fetched definitions that are given for the velopment of no special physical dexterity, | March, 1995 To Each Purchaser Wee id Battery \ A2%4-Volt’ Storage Batters FREE with each qurchase of OR ee “A” Storage pean he W. LD Battery is fa. Mat and service, by years of Becossstul Manuf ousands Satisfied Users. You save _ -” Prices That Save and Satisfy Auto Batteries Radio Batteries 6-Volt, 11 Plate $12.25 G-Volt, 23 Plate 14.25 §-Volt: 100 Ames: } 42-Volt, 7 Plate 17 100 event 140 ii: Shipment E: t nation 5 per cent tek Te cash sutioct te te cain 2-Yr. Guarantee Bond in Writing With Each World Storage Battery Tov tis: ance. , tne ee re eee wil Tehip Patiery de Lr hy alive ed; and le Seo en a to Or ie FREE: tit ies Oba WORLD BATTERY COMPANY 1219 So.WabashAve. Dept. a CHICAGO, gr Tie Bt dy “B’’ Storage » Battery tak rick, Can be ed mad the eee sade teries, To be sold retail for $6. 00. aC 3 the on nly y battery fpped with solid rubber case—and in and eakoge. Take pavantese of this remarkable offer NO (To thos: no peat it, we will vend handsome nickel finish Z Auto tlite, instead of th: tery. Be sure to specify which is wanted.) GIVEN FREE To introduce new an superior World Battery to the attery Public mz a. PLUG With Polyplug you get maximum clearness from your set, because you can’t mistake the Positive pole. The positive poleis plainly marked on the sleeve contact, Polyplug has no screws to tighten— no need to take plug apart. Wires are crossed under the ten sion slot — exclusive Polyplug feature — and plug- ged in. Pulling and jars do not disturb contact. POSITIVE POLE Permanent Positive Contact PLAINLY Made of Genuine Bakelite MARKED Send for Circular H POLYMET Mfg. Corp. 70-74 Lafayette Street New York City rll Pa Vy Ve LY) A Wear. : or of er. only a FREE OUTFIT necessary. Full or spare time. Cash profits experi Eo first two aa s — Bryce made $645 ii one lo the same. No cha or exclusive territory. (Continued on page 165) fter today. M RLE MFG. CO., Dept. ern “Rurora, 1S) This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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__—__—— oa Why Everybody Is Solving ~ €ross-Word Puzzles (Continued from page 164) missing words. Curiosity, activity, and constructiveness unquestionably are dis- played by every one who tries a puzzle. But does performance of the puzzles, as we hear it frequently maintained, actually “improve the mind’? Cross- word puzzles are confidently supposed to increase our power of concentration, to help our memory and our reasoning ability, and, by demanding decisive judgments, are even regarded as an aid to the will! It would require a whole course in psychology to present an adequate criticism of these views. Suffice it to say that we no longer believe in vague, general “faculties of the mind.” A person may strengthen the biceps in his arm by pulling chest weights and find this in- creased strength useful in playing base- ball or hoeing potatoes; but it does not by any means follow that the brain behaves in the same way. ° S A matter of fact, it doesnot. Mus- cles are organs of contraction, where- as herves are conducting organs. Like a telephone system, they convey messages. The effect of exercise, of education, is to plug in certain connections more firmly so that they become relatively permanent. Then it becomes easier and easier tosend a new message if we use the old connections. But it also becomes harder to send a mes- sage that requires that the old connections be broken up and new ones formed. Thus exercise, which increases the effi- ciency of the muscles, actually may im- pair our ability to perform certain mental operations. This phenomenon is known as interference. Fortunately there is no interference effect, so far as is known, in connection with cross-word puzzles. Language. practice is generally valuable because we use language a great deal. But neither is there any marked degree of ‘‘ carry-over”’ into other activities. Doing cross-word puzzles may improve your mental habits somewhat in that it causes you to con- centrate more narrowly than may be your wont, but it is altogether unlikely that it will improve your thinking in other fields. F YOU wish to increase your efficiency in studying French, or in tinkering with radio outfits, or in playing bridge, or in selling life insurance, the best thing to do is to practise thoughtfully and intensively in the field you wish to improve. Cross- word puzzles will increase your vocab- ulary, yes. Perhaps they will play a use- ful réle in keeping you out of mischief. But as for promoting any general im- provement of the mind, neither cross- word puzzles nor any other single discip- line can be expected to have much effect. So do cross-word puzzles if you will, but be honest with yourself and ad- mit that you do them for the same reason that you go to the theater or tread novels—for the fun of it. Innocent amusement is sufficient excuse in itself, and cross-word puzzles are innocent amusement—nothing more nor less! ~~. POPULAR SCIENCE MONTHLY 165 Handsome - Safe ~ Fast ASU: —charges in one-third the time required by @or3 ampere chargers, Radio’s Most Popular Battery Charger VER 250,000 Radio fans have found the big capacity 5 ampere GOLD SEAL HOM- CHARGER ideal for keeping their Radio batteries fully charged and operating at top efficiency. Connects to any lamp socket and charges all Radio ‘‘A’’ and ‘B’? and Auto Storage Batteries overnight for a nickel. Can be Contains no Simple, reliable, fool-proof. operated by any one. bulbs, acids or fast wearing carbon contacts. Only one moving part, re- placeable for $1.00 after thousands of hours’ use. Absolutely safe—no danger of shock or fire. Approved by Insurance Un- derwriters everywhere. Beautifully finished in mahogany and gold. May be used right in the finest living room. Price, $18.50 complete for all currents. Sold by all good Radio dealers, or shipped charges prepaid upon receipt of purchase price. THE AUTOMATIC ELECTRICAL DEVICES CO. 131 W. Third St., Cincinnati, Ohio tS) Largest Manufacturers’ vibrating rectifiers in the world. Write for booklet, ‘“The Secret of Distance and Volume in Radio,” containing information on this subject and fully describing the GOLD SEAL HOMCHARGER. Tee aaa an n'n'e' aaa ans a a ass 1a a ns a a” “The New Colonials” os 50 Houses—6 to 10 Rooms—$1 **All American Homes” 50 Houses—7 to 10 rooms—$1 “South-West Stucco Homes” 75 1 & Bungal $ 'DLANS for HOMES Pp s—> » “West Coast Bungalow Books” bao ad " tj 5 to 7 Rms. $1; 3to5 Rms, $1 E. W. STILLWELL & CO., Architects, 289 Calif. Bldg. Los Angeles “WONDER” COLD PIPE, TUBING & BAR BENDERS HAND and MOTOR OPERATED 14 Sizes of Machines What it costs to bend pipe our XK 5 ay 1" bipe Scents’ 4°" pipe 25 cents Fe SA °° Dide 10 cents 6° pipe 60 ce * a) pine 1 ppe $1.08 Send for Catalogue. AMERICAN PIPE BENDING MACHINE CO. 51 Pearl St. Boston, Mass. S plan. 350 Household © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. 1 OfferYou $100 aWeek | ca ; for yourself. Be your own boss, work when you spare time or ve! ful time, and make from $25 to $100 a week, niet Ford Auto Given Free, We want men and women to represent us. Wonderful Necessities direct f, to home. ‘We provide all instructions and equipment in- cluding automobile. Write q' AMERICAN PRODUCTS CO., you Can establish a b rom factory uick for offer. Dept. 1176 Cincinnatl, Obie,

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POPULAR SCIENCE MONTHLY Approved! AGNATRONS have re- ceived the unqualified ap- proval of radio engineers and radio fans alike. All who have ever used these vacuum tubes have become convinced that they have no superiors. ‘ | MAGNATROMNS have been approved - > by the Popular Science Institute. After | thorough tests by engineers of recognized 3 standing, this institute has given its d endorsement. MAGNATRONS will give better results in your set. Theimprovement in tone and volume and distance will sur- prise you. Ask your dealer today! CONNEWEY ELECTRIC LABORATORIES 309 Fifth Avenue New York City March, 1925 Based on Perfection EE of Parts—in U. S'Tool Condensers A CONDENSER is no more efficient than its weakest fea- FACTORY ture—a thought borne constantly GUARANTEE in mind in designing and making U.S. Tool Condensers. As a re- => | sult, the gradual perfecting of each Write / part has led to the nearest point approaching condenser perfection. : for Ask your dealer to show you Literature Type 6, with the micrometer dial. U. S. TOOL COMPANY, INC. 127 Mechanic St. Newark, N. J. Mfrs. of Special Tools, Dies, Jigs, Automatic Machinery and Sub Presses CHIC Aen RE _ ater ene 0 Ata ——_ © = | ee Now Comes the Air Taxj (Continued from page 47) Another safety device is the adjustable wing. The larger the lifting surface the less the speed may be. A racing machine must dash along at a terrific rate to get off the ground. The same plane with double-length wings can take off at about 25 or 30 miles an hour. This fact has led to building wings that can be contracted after the plane gets well clear of buildings and other traffic. By this means agg. dents should be reduced greatly. MULTIPLICATION of motors is an- other barrier between the passenger and harm. Four motors mean that the chance of breakdown is four times less than with one motor. Special landing gear to break the force of an emergency drop in rough ground has been designed, A new-type compass that prevents the pilot from getting off his course has been invented. Self-stabilizers make it nearly impossible for a machine to be upset by a sudden gust of wind. Constant radio communication and guidance add a sus- taining tone of reassurance to the passen- ger cabin. Speaking broadly, air trans- portation is just like the subway, the auto, the steam railway, and all the other mechanical vehicles of the age — early stages of development were stained with tragedy, and only after many safety de- vices were perfected was public confidence won. The type of air taxi we may expect will be somewhat different from that in use today. Between our Eastern coast cities fast planes are in service carrying but a few passengers, two or three as a rule. Between Paris and London flies a type that is comparable only to a private yacht. The latest plane carries 19 pas- sengers and baggage. It covers the 245 miles between the French and British capitals in about 114 hours, or at an ‘average speed of nearly 140 miles an hour. This machine is equipped with four engines and carries a useful load of 1% tons. A similar ‘‘sky bus” is being manufac- tured in the United States by what is characterized as the “first air Pullman company in America.” Thirty of the buses are in process of construction and will be in operation soon. Seven pas- sengers and more than a ton of baggage will be carried. The passenger cabin hangs below the wings, permitting a view in every direction. The cabin contains six long, deep upholstered seats with plenty of leg room, facing each other in pairs, and with card- or dining-tables be tween. Radio, dining, sleeping, and first- aid equipment will be of the finest. Be by far the most fascinating pros pect lies in the direction of the “fliv- ver taxi.” It has been said on good authority that Henry Ford contemplates the possibility of turning them out in vast numbers in his plant at Dearborn. Hes quoted as saying: ‘‘ As soon as we know a8 much about them as we do about auto mobiles, and that will not be long, then they can be manufactured by the thou- sand or by the million.” (Continued on page 167) © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. Marcl

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1925 March, 1925 is . lca i Now Comes the Air Taxi (Continued from page 166) ble An advanced edition of the flivver taxi the came not long ago in the shape of the ine little speeder brought to this country by get | the Frenchman, Georges Barbot. The rith total weight of his plane was only 400 out pounds, engine and all. In quantity, it led could be manufactured for less than $500, ted which puts it in a class with our cheapest ings automobiles. It was able to make 60 eci- miles on a gallon of gasoline. M. Barbot declares that eventually he will make 125 miles on the same amount. an- / The British “Wren” is another flivver- nger type plane. It weighs only 335 pounds, the carries a two-cylinder engine, and is said less to get 100 miles on a gallon of gas. The ding weight given inclutes pilot and fuel. ancy Empty, the little craft tips the scales at ned, just over 200 pounds. the The significance of planes of this type been lies chiefly in economical operation. Rail arly travel at three cents a mile seems pretty bya cheap on first sight when compared with ‘adio the present air-taxi service of about 35 SUS- eents a mile. But other factors must be ssen- taken into account. A taxi-plane travels rans- from three to four times as fast as a train the and covers (because of its crow flight) ther only about 70 per cent of the distance. early What this means may be gathered from a with statement by a banker to the writer. He 7 de- said: ‘‘I estimate that $1,000,000 is saved lence : every three days to the banking interests ; of this country by the air mail. The reason ; will is that the interest charges on securities is L use less than half during transportation by cities air than it usually is by rail.” out a rule. Pp THIS connection it has been brought type out that Europe is a better country for ‘vate air-taxi service on account of the small pas- distances involved. Yet the very fact @ 245 that our distances are so great is what ritish will assure the success of such service in at an America. With the pressure of business "8 an requirements, we shall have to turn to air with _ | travel for relief. Thus the air mail, which ad of operated last year at a profit of something close to $100,000, cuts from 86 to 90 nufac- hours from the rail time necessary for a hat is transcontinental trip. Iman Few people realize that the Govern- f the ment has gone unostentatiously forward n and in the development work necessary to the 1 pas- success of commercial flying. The Army iggage and the Navy and the Postal Service have cabin given much study to meteorological con- a view ditions over our country. A “model air- ntains way” has been developed by army fliers _ with connecting the various army aviation her in centers from coast to coast. Planes travel les be- over this route exactly as trains traverse d first- the lines of a big railway. All planes move on schedule and receive radio instructions from headquarters. 5 Peet. The whole country already has been > “*fliv- mapped from the air, showing the best air . good routes between any two points. An avia- plates tor who never has flown in the United in vast States can get into a plane at any army He 1s | « base and find his way to the smallest now as Village in the country by this means. He t auto- 8 supplied with index cards showing z, then Toutes, directions, and mileage for the > thou- entire area. In fact, the present-day air guide-book is very little different from our auto Blue Book. POPULAR SCIENCE MONTHLY 167 Balkite Battery Charger. Charges 6 volt “A” storage batteries. Price $19.50 West of Rockies $20 | In Canada $27.50 An unfailing power supply for both circuits battery charged. Balkite“B” replaces “B” batteries entirely and furnishes plate current from the light socket. Both are based on the same principle, are entirely noiseless, and are guaran- teed to give satisfaction. Sold by lead- ing radio dealers everywhere, ‘Balkite 224%. BALKITE BATTERY CHARGER = BALKITE “B” PLATE CURRENT SUPPLY Manufactured by FANSTEEL PRODUCTS CO., Inc., North Chicago, Illinois Balkite “B”—vre- places “B” batter- ies and dry cells. Operates from light socket. Price $55 Y oe Hereat last isan unfailing power sup- ply for your radio set. Balkite Radio Power Units furnish constant uni- form voltage to both “A” and “B” cir- cuits and give your set greater clarity, power and distance. The Balkite Bat- tery Charger keeps your “A” storage 7 00 arneG montx i" A New Business—Big Business A Business to Enthuse Over — The “Ideal” Lawn Mower Sharpener A wonderful invention that shar lawn mowers scientifi- cally—quickly—perfectiy; does the work as nothing else can. FRED C. MILKERT OF ROSELLE, ILL., WRITES: “The Ideal Lawn Mower Sharpener put me in business, starting in the basement of my home and forcing me now for the third time to move into bigger quarters. Today the dream of my life— a shop of my own —is realized. With amachine like yoursandalittle hustle any man can havea business ofhisownand beindependent. D. H. NOAKES, MILFORD, OHIO, WRITES:‘‘Several years agolI started sharpening mowers keg z 10 —— ines f I own a store of my own on Main Ave., No, 212, valued at $8,000.00. The * Grinder didita W. F. KENDT, BUFFALO, writes: ZENO BRANDON, MIDDLE- taney wo Isharpened 994 lawnmowers last seae TOWN, OHIO, writes: “I made “ aT * gon, and the receipts were nearly $820.70 in 65 days with my Ideal.’ Ps Es cdl $2100.00 which is not bad Have made as high as $38.70 in one for which I received f Zor a side line.” day." Not t il 00,” : o town toosmall. _ You Start Now Lawn mowers are dull—owners don’t know where to get them sharp- ened. Mowing the lawn dreaded because of dull or ee, gra! sharpened mower. Lawn mowing / healthful, invigorating and pleasant when Mower is ‘‘Ideally’’ sharpened. You do the work scienti- fically—you are in big demand. Lawn Mowers Sharpened to Razor Edge= People glad—owners delight in mowing lawn with mower sharpened onan ‘‘Ideal.’’ Mower runs light—click-click-click and the grass is cut, Build permanent business for yourself. Start now! WRITE TODAY ,aaume USE THIS—MAIL IT TODAY : — Detailed Free illustrated The Fate-Root-Heath catalog and booklet @ _ High and Boll Sts., Plymouth, G. ‘“‘Let George Say ikiet" LetGeorgeSaylt.* Cachan ituckict LetGeergelagt e' It." Write today. _, @, asiorendteokiet'iaison si The Fate-Root-Heath Co. EEE 9 ae High and Bell Sts., Plymouth,0.; @ PUP PeeUCCOCCCEI IOI Cee ditnaeetnglt

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¢ POPULAR SCIENCE MONTHLY ) ] | | | MURDOCK NEUTRODYNE “Now $Q2-50 Announcing.» NOTICE F your dealer doesn’t sell Murdock Pro- ducts write for beautifully illus- trated booklets giving complete description of all Murdock i} Products. WM. J. MURDOCK COMPANY, Sales Offices: New York, Chicago, San Francisco, Washington, D, C. MURDOCK RADIO PRODUCTS $25.00 in PRIZE onsea by A Monul yor eS Omer Patents Pending od word sn Sea The new Murdock 5-tube Neutrodyne with “B” bat- March, 1935 tery compartment—backed by 20 years experience in making fine Radio Products. 430 Washington Ave., Chelsea, Mass. Standard since 1904 See top page 8 in front of book for details our name on our tionally advertised facto: ** proved apparatus is listed in our monthly bul- letin: ““The American io Transmitter.” If it’s new we have it. J * Lowest Prices in U.S. Our prices to dealers are the lowest in the United States. All nationally advertised goods at discounts that mene yea real money. Dealers, es = monthly bali Simply send name i 4,850 items. AMERICAN RADIO MFG. CO. 6 W.141h Si. Dept. B., Kansas City, Mo, As one of the oldest pat- ent firms in America we give inventors at lowest consistent charge, a service noted for results, evidenced by many well known Patents of e value. Book, Patent-Sense, free. Lacey&Lacey, 648 F St.,Wash., D.C, Estab. 1869. PATENTS ITRADE-MARKS, COPYRIGHTS AND PATENT LITIGATION Write for advice and instruc- tions how to proceed, costs, etc. Hand Book with illustrations of 100 Mechanical Movements sent free on request. ALBERT E. DIETERICH Patent Lawyer and Solicitor Successor to Fred G. Dieterich & Co. 681A Ouray Bidg. WASHINGTON, D. C. ulletin, showing 75 na- | world, was forecast by a rain of ash that | bureau, that was established more than | unusual chances to achieve fame by mak- A New Way to Pama (Continued from page 54) frightful catastrophes in the history of the fell over the surrounding country for g couple of weeks before the eruption. The inhabitants of the city of St. Pierre did not heed the warning, though, and were destroyed. To people who live in lands where voleanic eruptions are unknown the reason for such a science as voleanol probably .is not apparent, and yet the study of volcanoes bears an intimate re. lation to them, no matter where they live. Mount Rainier in Washington Mount Shasta in California, and other great mountains of the United States are potentially active voleanoes. A few miles below the streets of cities like New York and Chicago there is lava, for the whole surface of our earth rests on lava. What we are doing is studying the character. istics of this lava at the active volcanoes where its action is to be seen, and we hope to work from them to the volcanoes the activity of which is buried far under- ground. bares are about 425 active volcanoes on earth, but only three or four of them are being studied. On Vesuvius is an observation station, formerly a weather 50 years ago. There are two stations at Asuma in Japan, established by the late Professor Omary, the famous seismol- ogist. There has been a station at Taal in the Philippines since 1911. These and our station at Hawaii are the only ones. There should be at least 200 stations if the mysteries of volcanoes are to be investigated fully. Forty years ago when there were but a few weather bureau stations, weather forecasters could only generalize. Now, though, with the coun- try studded with stations, telegraphed reports from one to the other permit meteorologists to predict with remarkable accuracy a change in temperature, a storm or some other variation in the weather. In the same way the crust of the earth could be studied, and its movements followed. Present-day knowledge in meteorology and astronomy — in all sciences in fact—rests on the facts and figures that have been piling up through the years. FoR young men who are in search of a career I have a suggestion: Become a voleanologist. It is a calling that offers thrill, ad- venture, interest, excitement, and the opportunity to perform scientific work of extraordinary usefulness. It is a new profession that is anything but over- crowded, and hence provides for pioneers ing new discoveries. These are its ad- vantages. To my mind it has no dix advantages, although others may not agree with me when I tell them that it must be followed for the most part m remote, out-of-the-way places, and that it entails a great deal of patient, hard work without offering a single chance of achiev- | ing wealth. OC © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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‘the that or a The did were here the logy, the € re- they zton, other S are miles York vhole What cter- noes 1 we noes nder- an oes ur of ius is ather than ns at » late smol- Taal > and es. tions (0 be when ireau only coun- phed ermit kable re, 8 . the earth nents e in 1 all ; and ‘ough | of a come , ad- | the rk of new over- neers mak- 3 ad- y dis- * not rat it rt in that work hiev- March, 1925

Se Here Are Correct Answers to Questions on Page 79 1. The lowest temperature ever obtained is that of frozen helium gas. This is about 272° below zero. C. (458° below gero F.). ‘This is within one degree of what is called the absolute zero, which is a theoretical temperature at which the atomic vibration 1s supposed to cease alto- gether. : Fi 2. About 310,000,000 cubic miles of water. ‘| 3, We are not sure. We know that there is some medium by which radio waves, light waves, and heat waves pass through space. 4, The white corpuscles, called leucocytes, tiny granules of whitish jelly floating in the blood. If a germ gets into the blood, a white corpuscle soon finds it and engulfs the germ inside its own body, where it is killed and apparently digested. 5. There is no exact limit. It depends on the way the current passes through the body, on how long it lasts, on the general health, and so on. Ordinarily there is no danger from the usual house-lighting cir- cuits of 100 to 120 volts, but people have been killed even by these circuits under unusual conditions. On the other hand, persons have survived even several thou- sand volts when the shock was only mo- mentary. 6. Soap contains a material that has the ability to stick very tight to things. It creeps over their surfaces as a film of oil will creep over the surface of water. When you wash your hands a very thin film of this material creeps underneath particles of dirt sticking to your skin and pushes these loose so that the water can wash them away. 7, Because they slowly use up oxygen and give off carbon dioxide. That is, they breathe just as all other living creatures do, though much more slowly than grow- ing plants or animals. 8. No. Some of them must be liquid. They are too light, in comparison with their size, to be solid. Jupiter, Neptune and Uranus are only about one and a third times as heavy as water, much lighter than any known rock. Saturn is lighter than water. 9. The arteries carry the fresh blood out- ward from the heart to the muscles and other parts of the body. Veins carry the gees blood back to the heart and ungs. 10. Scientifically, they are more like the yellow race. It is probable that the negro race split off from the primitive stock of mankind many thousands of years before the whites and the yellows separated into two races. 11. Iridium, a metal that is somewhat like platinum but much harder. This is why it is used for pen tips. It wears away much less rapidly than gold and it is equally resistant to corrosion by the ink. Look at the under side of your pen point and you will see a little whitish speck. That is the iridium. 12. Very little. Since the wave goes out in all directions from the station, the power in it becomes rapidly weaker. Dr. Willis Whitney has pe that the power exerted by a fly climbing one inch up the wall is equal to the power that would be picked up by a one-foot loop an- tenna in Schenectady, N. Y., from the Oakland, Calif., broadcasting station ring a continuous time of 35 years.

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FOR years the Columbia Eveready has been the outstanding dry battery. A familiar favorite for a thousand and one every-day electrical jobs. If you discover in this publication or elsewhere something new to try your skill, use Columbia Evereadys for power. They are strong from start to finish. Remarkable for their ability to revive their punch between jobs and to retain their pep and power. For all dry battery uses— Columbia Evereadys. They last longer. Manufactured and guaranteed by NATIONAL CARBON COMPANY, Inc. New York San Francisco Canadian National Carbon Co., Limited, Toronto, Ontario Popular uses include— 4 gas engine ignition telephone and telegraph doorbells buzzers motor boat ignition heat regulators 1 tractor ignition starting Fords ringing burglar alarms | protecting bank vaults 1 electric clocks calling Pullman porters © | firing blasts lighting tents and outbuildings ] running toys radio “A” Columbia Evere eady Hot Shot Batteries contain 4,5 o0r6 cellsina neat, water-proof steel case. Fahnestock spring clip bind- ing posts on the ignitor at no ex tra cost to you. Ask for them by name at electrical hardware radio automobile marine supply implement and general stores

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i

POPULAR SCIENCE MONTHLY

NYONE can own a big set now. The four-tube KODEL with its marvelous range and vol- ume, its amazing selectivity, its clear full tone, matches the performance of most expensive five- tube sets, and costs less than half as much. KODEL is a quality receiver. Sockets and dials are of genuine Bakelite; panel of highly pol- ished Formica; cabinet of hand- some black pebbled leatherette —KODEL is Radio’s Great Set Value. Before you buy any set see the complete KODEL line at your radio dealers—‘‘compare the quality.”

Here Are All the KODEL Models S-1 Crystal Set........0. $ 5.00 C-11 One Tube Set........10.00 C-12 Two Tube Set........ 18.00 C-14 Four Tube Set...... 32.50 P-11 One Tube Portable..16.00 P-12 Two Tube Portable..22.50 If your Radio Dealer cannot supply you, we will ship direct. Write for complete catalog. e..- KODEL is the sensation of the season. DEALERS: Fansthe country over are buying KODEL for its remarkable performance and its amazingly low price. Write for illus- IS) trated catalog of the complete line of KODEL quality receivers. THE KODEL MANUFACTURING CO: 131 W. Third Street CINCINNATI, OHIO

All late models, compl Fishes brand new. GUARANTEED for ten EARS. Send saconurgiday fess cil cfr np ata ree 5 ° le mernational Typewriter Ex. 186 W. Lake St. Dept.235 Chicago © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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March, 1995

- : ee Radio Control | (Continued from page 89) magneto (such as is used in an airplane or order to neutralize it by radio waves it an almost immeasurable amount of rH tric energy at the sending station.” Pure radiodynamics may be sgaid to have progressed in three different dire. tions, though the principles in each line are exactly the same: 1. Radio-controlled boats or torpedoes; 2. Radio-controlle land vehicles, such as automobiles anq tanks; 3. Aircraft. OHN HAYS HAMMOND, Jr., has been a leading proponent of radio. dynamics. Nearly 15 years ago he began a series of experiments at his wonderful private laboratory at Gloucester, Mass, There he developed a wireless system capable of controlling a crewless 40-foot gasoline launch of 150 horsepower and making a speed of 25 knots. This vegge] proved wholly obedient to the operator's far-distant hand on the land. It darted to and fro. It started and stopped. In every way it proved itself the servant of its master physicist ashore. As a sample of a radiodynamic vehicle, there was built later at the Hammond laboratory what was termed an “electric dog.” This was a boxlike carriage on wheels containing a driving mechanism and a system of electromagnets operating its steering gear. Controlling waves were not invisible radio waves, but visible light waves. The ‘‘dog” was fitted with two selenium tubes, or cells, like eyes. These cells were highly sensitive to light. When the light rays struck them, a minute elec- trie current was set up, which in tum operated two very delicate relays. When both cells were illuminated, the driving mechanism worked and the “‘ dog” moved toward the light. When only one cell was lighted, the steering mechanism on the side of that cell was energized and the ‘dog’ swerved. The aggregate behavior of this device, therefore, was to move faithfully, almost as if alive, in the direc- tion of any source of light; and, if there were several sources, to pursue the strongest of them. MEANS for guidance of the pilotless dirigible or plane are derived from exactly the same sources as described above for ships or motor-cars. So far, the great trouble has been that aircraft move in three-dimensional space and so require an extra set of controls. But even this obstacle was overcome by the army at McCook Field last spring. That brilliant young aviator, the late Lawrence Sperry, flew many times over Long Island as 4 passenger in a speeding plane guided wholly by radio from below, his hands not touching the controls. Thus we have as accomplished facts the crewless ship, the chauffeurless automobile, and the pilotless plane. What next? Next can come only such miracles as came with a rush when the gas engine was perfected. Take first the crewless ship. There is good reason to believe that some day every lake and bay and sea will con tain many thousands of them. With the

March, perfec need namic mari and n space and f gonne stroke O* I We di ster fc a cent as fee what contr¢ come. The no les: It is ¢ will hh years ardor farme! coolly electri then ¢ the rei if we ¢ the cc flux ¢ bound send h by sw ing se’ as a | stoppe electri But nificar wilder plane. 6“ Th has be submé 1000-] York these city | that 1 vent. life wi could dawn RR us abuse: war W one of state that 1, and dama; huma’ fore t! men c Son tadio- est fir pilotle

(Continued on page 171)

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lane op ul, In aves it require fees aid to direc. ch line trolled trolled eS and R., has Tadio- began nderful Mass, System 40-foot Pr and } Vessel rator’s darted od. In vant of ehicle, nmond electric age on hanism erating eS were le light th two These When te elec- in turn When driving moved cell was on the ind the ehavior » move e direc- if there ue the pilotless od from escribed far, the ft move require ven this army at brilliant Sperry, id as 4 guided s hands| | facts the tomobile, ct? racles as gine was ess ship. hat some will con- With the Radio Control (Continued from page 170) rfection of motive mechanism we shall need only the simple control of radiody- namics to send whole flotillas of speeding marine automatons on their way. Freight and mail both will be carried. Enormous ace lost nowadays for living quarters and food, as well as great expense of per- sonnel, all will be banished at a single stroke. F COURSE,: such unique achieve- O ments would not come overnight. We didn’t have the modern flashing road- ster for something more than a quarter of a century. And the first autos were just as feeble and awkward, compared with what we ride in now, as to-day’s radio- controlled automaton may be to what will ome. : The chauffeurless shore vehicle will be no less profitable when we learn to use it. It is conceivable that automatic tractors will lumber out across the fields, a few years hence, and plow with quenchless ardor under the fiercest solar heat. The farmer? Why he, the loafer, will loll coolly in his radio watch-tower before an electric fan, only moving a finger now and then on the slender control keys that are the reins of his mechanical plowhorse. Or, if we come to motor parkways throughout the country with smooth, uninterrupted flux of traffic, it is quite within the bounds of imagination that a man may send his car back home for the wife simply by switching on its radiodynamic receiv- ing set. The car then will travel straight as a bee for its destination, save when stopped by the unseen radio hand of an electrified traffic cop. But even these marvels fade to insig- nificance when we contemplate the be- wildering potentialities of the pilotless plane. “The weapon without an antidote” it has been called. For we can picture 100 submarines carrying 100 planes and their 1000-pound gas bombs arriving off New York without detection, and sending these planes under radio control into the city before daylight. A gas attack of that nature would be impossible to pre- vent. Times Square and every vestige of life within 40 city blocks of Times Square could be annihilated before the blood-red dawn illuminated the scene of horror. Ret radiodynamics will be put to many useful purposes long before it is abused for any such gruesome tasks as war with gas suggests. For example, take one of the latest economic tragedies in the state of New York, the fierce forest fires that last fall raged up through Rensselaer and other counties, doing irreparable damage to precious forests. All available human agencies were pitiably helpless be- fore the holocaust. The trouble was that men couldn’t get at the fire. Some day in the not distant future tadio-controlled ‘planes will fight our for- est fires for us. Because they will be pilotless they will be smaller. For the Same reason they will be cheaper. They will be able to take chances that the bravest pilot would never take; for their 088 never would mean the loss of human ell (Continued on page 172) ee POPULAR SCIENCE MONTHLY Supereflex Means MORE POWER PER TUBE Erla Supereflex makes tubes do triple duty. One tube actually does the work of three that would be needed otherwise. Three tubes do the work of five, unquestionably! That is why simple, compact, inexpensive Erla Supereflex receivers equal or surpass the performance of costliest, temperamental multi- stage radio sets. More power, tube for tube, is basic in Erla Supereflex. Noth- ing else can “‘make up for it.” Greater power in Erla Supere- flex just simply means finer radio, which you can afford. For you yourself can confi- dently build these matchless Erla circuits with Erla Supere- flex CIR-KIT. CIR-KIT is a complete array of Erla Scientific Precision Ap- paratus, especially created to make Supereflex possible. C/R- KIT provides clear, simple m- structions for perfect assembly. Blueprints are full size. The panel is pre-drilled for you. The baseboard is marked to locate every unit accurately. The fa- mous Erla SolderlessConnectors do away with soldering entirely. With screwdriver, pliers and CIR-KIT you are sure of a set that will make you proud, both for appearance and perform- ance. The cost is very moderate. Yet the range, volume, selec- tivity AND TONE PURITY are rarely equaled at any price, because Supereflex does give you more power, tube for tube. Electrical Research Laboratories Department S, 2500 Cottage Grove Avenue, Chicago ° - : Beautiful Raceabout Drive This LEN Sa Instead of Your OLD FORD anes ae | , Choice of Four ffs — Colors ; Fiat or the 7 Bullet Nose Rad- % MPM iiator Shell. Send . = {Wey for 1925-Free Cat- Z eRe, alog of New Auto — : _Acces’, Bodies and Speed Equipment. Direct from Factory. AMERICAN TOP AND BODY CO., Beech Street DELPHI. IND. © HoNnEYCOMB COILS The Universal all-wave *\\ inductance. Back and front panel mountings. Send 25c for_ Super Het., R. F. and Honey- comb Coil Circuits and fF =Complete Catalog. Chas. A. Branston, Ine, Dept. 9, 815 Main St. Buffalo, N. Y. NEW VEST POCKET ADDING MACHINE hi Counts Up to 999,999,999 Total visible at all times. A pull of the finger clears it. Don’t carry a pocket full of pencil stubs and paper to do your figuring. Carry a Ve-Po-A: 10 Days Trial $en4 20 money. Pa -9. Use it 10 days to prove it does all we claim, If not perfectly satisfied we will refund your m& money. Limited supply. Send order today. Reliable Adding Mach.Corp.,Dpt. 74 170 W. Washington St., Chicago, Ill. —— Here’s a money maker, ; TAG ENT S beeen ieee tS} This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. C/R:K/T ee

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7a tars Et se ee ee eee i eS th sence. we a ean ees SE UNDE Ae Son de 172 When you see a man putting in his moon hour learning more about his work, you see a man who won’t stay down. He’ll never be satisfied until he hits the top. And he'll get there! In shops, factories, offices, stores, in every line of industry, men are holding splendid positions won through spare-time study with the Inter- national Correspondence Schools. To-day they are earning four or five times—yes, some of them ten times as much money as when they started. Employers everywhere are ‘ooking for men who really want to get ahead. If you want to make more money, show your employer that you’re trying to be worth more money. For 33 years the International Correspondence Schools have been training men and women right in their own homes, Thousands upon thousands of men have stepped up in just this way. More than 180,000 are studying now. Can you afford to let another hour pass without making your start toward something better? Here is all we ask—without cost, with- out obligation, just mark and mail this coupon! INTERNATIONAL CORRESPONDENCE SCHOOLS Box 7640-D, Scranton, Penna. Without cost or obligation on my part, please tell me how I can qualify for the position or in the subject before which I have marked an X: BUSINESS TRAINING COURSES Business Management ( Salesmanship Industrial Management L) Advertising Personnel Organization Better Letters Traffic Management Show Card Lettering Business Law Stenography and Typing Banking and Banking Law Business English Accountancy (including C.P.A.) (J Civil Service Nicholson Cost Accounting Railway Mail Clerk Bookkeeping Common School Subjects Private Secreta High School Subjects Spanish o French lustrating TECHNICAL AND INDUSTRIAL COURSES Electrical Engineering (0 Architect Electric Lighti: Architects’ Blue Prints Contractor and Builder Mechanical Draftsman Machine Shop Practice Ratiroad Positions Architectural Draftsman acme yond tructural Engineer Gas Engine Operating Chemistry (J Pharmacy Civil Engineer Automobile Work Surveying and Mapping : Airplane Engines ooooo0ooosgg ooooooo00o0o = 7 7 & 4 BE BS i=] a ® & Motaliersy D Mining Agriculture and P Steam Engineering () Radio Mathematics cule Name Street je 3-6-24 NE ribcotincciseebarkbcebicsnérccnpusmtiiebaaneroeiusotolessvooeescensoionsen sees. City.... --- Btate Occupation Persons residing in Canada should send this coupon to ‘the International Correspondence Schools Canadian, Limited, Montreal, Canada H $765 in four hours VUME spare time just wearing this Beauti- ¥ ful Hand-Tailored Cap, madeto his } Individual Measure, and you can do the same—you can easily earn $50— $75 a week in your spare time. Get This Cap FREE I want to give you thiscap FREE—I know your friends will be delighted with its Class, Style and Fitand you will make « generous profi‘ taking their orders. Choice of 5 styles and 25 fine fabrics. Send your name right away and I’11 tell you how to make 80a week in yourspare time. Write me at once. J. W. Taylor, Pres., Taylor Cap Manufacturers, Dept.9-C, Cincinnati, O. POPULAR SCIENCE MONTHLY | steadily for one hour. | bulb would put back into the battery half | an ampere hour during the same period. Radio Control—Marvel of the Future (Continued from page 171) : life.” They will be directed from a port- able station. Or they may even be driven in a chemical-carrying swarm before a mother plane. In either event they will save us millions and millions of dollars by eliminating the sickening annual loss by fire of our forested lands all over the country. Already we spray crops by plane. Farmers and ranchmen admit this method is unexpectedly successful. But the gov- ernment has to help; the farmer can’t afford to use the method. The pilot is too expensive. The radio-controlled pilotless plane is the only satisfactory answer. NE estimate of the annual value to the country of our official weather | reports gives the remarkable figure of $250,000,000. Without regard to its accuracy, this figure at least indicates how much agriculture and commerce of all sorts have come to depend on the weather man’s predictions. But, alas, we all know how often that much-maligned person makes mistakes. Soon, however, he will have radiodynamics to help him. In addition to a relatively few scattered observation stations, the United States Weather Bureau will employ hundreds of flying automatons that will be dispatched to circle afar and return like so many boomerangs. Each plane will carry a set of recording instruments that will bring back written messages accurately describ- ing weather conditions in the area cov- ered. From these records meteorological prophecy may cease to be a system of skilful guesswork and with their assist- March, 1925 ance take on the nature of a fixed science Radio-controlled planes doubtless yin be used to carry mail. Night fy; pilots and their awful perils no longer wil exist. A crashed plane may burn up afew letters, but never will it scorch the quivering flesh of an unconscious flier Such planes will leave the ocean liner after she has sailed and meet her before she lands, thus cutting the business-mail interval at least in half. | eat teabehahee wa advertising cam. paigns may be launched from timetg time with the express permission of the government and after paying a high tax. Automatons then will distribute a nation. wide spread of pamphlets describing 4 new brand of tobacco or scented soap, Miniature radio-controlled automatons will flit between skyscrapers carrying orders and inter-office memorandums. The explorer no longer will have his base of supplies in the wilderness, but near home. His men there will send him food and other luxuries daily by air. The man who commutes to his office by air even may be able to send his plane back home simply by turning its radio control over to one of the office force. It is all very thrilling to visualize. And it certainly all seems very far-fetched, Yet the writer remembers very well asa boy, less than 30 years ago, when a highly intelligent engineer said it might well be several generations before an engine were developed that would give us a practical automobile or airplane. We have them both today. How to Cut Down Battery Costs (Continued from page 90) charged at all times at Jittle or no cost to you for current. With this system it is desirable to test the battery with a hy- drometer once a week, and if you find you are taking more current out of it than you are putting in, it is easy enough to plug in the electric toaster in place of the lamp bulb and so give the battery an extra charge for a few hours. A five-tube set, using quarter-ampere tubes, takes 114 ampere hours of current out of the battery when the set is operated A 60-watt electric From these figures, it is easy to figure out whether the battery is likely to need an extra charge at the end of the week. — you connect the plate-voltage filter system shown in Fig. 2 with the binding posts of the receiver, and before you make the connections with the storage A battery from the triple-pole, double- throw switch shown in Fig. 1, make a careful test to determine which wire is positive, as shown in Fig. 3. Dip the two bared ends of the wire into a glass full of water into which a pinch of table salt has been stirred. You will note that bubbles will form and rise to the surface from the end of one wire. This is always the nega- tive. It is advisable to make this test on the two ends of the drop cord from the table lamp formed by cutting ome strand of the two that make up the drop cord. The three-pole, double-throw switch is used so the battery will be discon- nected from the power line and connected with the radio set when the switch is thrown to the left, as shown in Fig. 1, and at the same time the light circuit will be closed independently so that the table lamp can be used. When thrown the other way, the switch connects the bat tery in series with the light, after discon- necting it from the radio set, so that there is not any chance of a short circuit by way of the B battery supply filter system. Users of dry-cell tube outfits ordinarily find that the expense of renewing A bat- teries is greater than for B batteries. If} you have found this to be the case, @ simple way to cut down the expense for A batteries is to purchase a storage battery and keep it charged according to the dia- : gram in Fig. 1. N NEXT month’s issue, Alfred P. Lane, radio editor of POPULAR SG’ ENCE MONTHLY, will describe a § method of adding either one or stages of radio frequency. Here’s an unusual constructional article—one that thousands of io| fans have been waiting for. You won't want to miss it. we IS} This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33. Marcl

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POPULAR SCIENCE MONTHLY SILVERSTEEL SAWS HE finest saw Atkins ever made— the Elite of the Saw World. You will find the Atkins “four Hundred’ a wonderful saw. Ready for a lifetime of super-service in sawing. Blade of “Silver Steel,” taper ground to insure the easiest cutting, longest wear and edge holding qualities. Its genuine rosewood handle, the nickeled screws and polished blade indicate its extraordinary quality and workmanship. Ask your dealer. Pass All Tests | The engineers of Popular Sci- ence Institute place their seal on Atkins saws for acknowledged standards of quality, workman- ship and materials. Since 1857 the Atkins trademark has stood for even higher'standards on saws for every use in cutting wood or metal. It will pay you to look for the Atkins name on ANY Saw. ““Saw Sense, © Ihe Saw in the Shop,” or “The Saw on the Farm,’ are valuable books filled with saw information. We'll gladly send you any of them if you will address Dept. D-20— © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.

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Bring the romantic, enchanting, entrancing and melodious strains of the great instrument of the Hawai- ian Islands into your soul. Become ¥& Popular and successful. This short cut method of home instruction enables you to quickly master Hawaiian Guitar, , 80 you will play as well as Native / # Hawaiians. Our staff of Hawaiian instructors have perfected a method of teaching, so simple, that without musical / knowledge, you quickly learn to nlay real“ music from notes. Simple as learning ow. » C’s and it will not ve long fore you will play latest Broad- way hits. Only four agg ee >, er Anson ai get started, we when you enroll as a student, a beatiful, fuil tone. genuine, $18.00 Hawaiian Guitar. Only 1,000 free instruments given away; { if you want to get in on free offer, write > for particujars at once—you must act quickly. New Invention—Kno-All-Chart = FY STARA ome can understand it and begin to play immeaiately. Picture Method Easy We do not depend upon our printed instructions alone for your success as a student, but we also supply you with many pace of our professors’ playing. is enables you to mitate the pictures. isn’t this easy? Phonograph Records Free As an additional guide, we also furnish you with phonograph records of our Hawaiian instructors’ own playing of the piece you are i This practically brings our profes- sors from our studio to your own home and enables you to listen to their playing just as B if they were actually in front of you. Genuine $1 8% Hawaiian Guitar Free Enroll as a student, and secure free, a beautiful, full tone, | 18.00 Har Guiter. We also furnish every bit of equipment so it is never necessary for you to spend an Muar anko ae en 18 Hawaiian Guitar-when you enroll extra penny. hen you peecoste, you get a beautifully engraved dipioma and after grad- uation, we also os you six months’ free service and consultation. Send for free partic- ulars now. Send for Free First Lesson and Book So positive are we you will become one of our students, that if you write at once, we will send you ree, our first lesson which will enable you to see just what you can expect when you enroll. You will also receive our big book of full particulars. Write for your copy and free lesson today. You will be one of the lucky ones to have a free Hawaiian Guitar reserved for you— wi once, of New York Academy of Music 100 Fifth Ave., New York, N. Y. 3 & e. fam oe e . yew be \ : Na ao | . oo ee Do it through Hawaiian Guitar POPULAR SCIENCE MONTHLY $ Brings you a Genuine Be UNDERWOOD TY PE WA FT ER: 10 DAYS FREE TRIAL Fort $3;°0nncon ne days you are not satisfied with this late model ERWOOD tepensiter rebuilt by the famous Chipman Rey GREAT PRICE SAVING Pitect,te vox from the : . writer fac- tory of its kind in the world by our money saving me:hods, EASY MONTHLY PAYMENTS §¢.s™i ‘tst ou will not notice it while you enjoy the use of this wonderful machine. » FREE BOOK OF FACTS Wags scnderta system of rebuilding vg 5, ER type : Year pm és Guarantee nt é Vine zloupon - an ed Shipman Ward Please send me a Mf¢. Company S266 lovenoweed Ate., Chicago a Name NS react Weas ds ou 6's a wae 0s wen veccel City State = Reet xe Soe Se Sa A Ce a a How to Build a Two-Tube Se (Continued from page 93) i Be sure to place socket L with the grid and plate binding posts toward condenser E, and fasten socket M with grid and plate binding posts toward the rear, so that the filament binding posts on this socket will be nearest the panel Q. The audio-frequency transformer J should be placed with the secondary binding posts toward socket L and the secondary bind- ing posts on transformer J should be toward socket M. You will note that in the wiring dia- gram given in Fig. 6, all the wires that go to make up a one-tube receiver are marked in solid lines, while dotted lines are used to indicate the additional] wires necessary if two tubes are to be used. The following description of the wiring will cover the necessary connections for two tubes. If you want to build the re- ceiver as a one-tube outfit, just disregard the instructions specifying wires that are indicated by dotted lines in Fig. 1. In- cidentally, this is a good plan if you live near several broadcasting stations, since one dry-cell tube will operate a loud- speaker with good volume. A EACH wire is soldered in place, go over the Jine that indicates the wire in Fig. 1 with a blue or red pencil. This will enable you to note any wire that you may accidentally have missed. Do not forget the positions of tuning in- ductances AB and CD, and be sure to bend the wires so that they will not interfere with them. The filament circuit should be wired first. Run a wire from binding post No. 8 to one binding post on the rheostat K. From the other binding post on the rheostat run a wire to the nearest fila- ment terminal of socket L and continue it around to the left-hand (as seen from the rear in Fig. 1) binding post on socket M nearest panel Q. Next, run a wire from the binding post No. 4 to the re- maining filament terminals of both sockets L and M. Now connect a wire from the stator plates of condenser E to the grid terminal of socket L, and another from the rotary plates of the same condenser to one of the secondary terminals of transformer I. Connect the other secondary terminal of the same transformer with the wire that runs from binding post No. 3 to the rheostat. Fixed condenser H can be soldered between these two wires at any convenient point. See Fig. 6. Binding post No. 5 can be connected directly with binding post No. 4. Bind- ing post No. 6 is next connected with the top soldering lugs of jacks O and P. Running a wire from the other lug of jack P to the plate terminal of socket M completes the connections with this jack. The crystal detector N now can be wired. The lower terminal of it is con- nected with the stator plates of con- denser F and the other terminal goes to the nearest primary binding post of transformer J, The remaining primary terminal of transformer J goes to the rotary plates of condenser F. If you are building the complete two- tube set, the next wiring is to “a . up transformer J. The grid terminal, this transformer goes to the grid te of socket M; the filament termina] is connected with the wire from bi post No. 3. Now screw coil CD in and run a wire from the upper of coil C to the lower lug on jack 0, At, this you can connect the second frm| | the bottom lug of jack O with the plate terminal of transformer J, and the | to the top lug of jack O with the phy! | B terminal of the transformer J, 2 Now run a wire from the plate bing post of socket L to the other terminal coil C, and from the wire running fron the jack to this coil, connect the xs condenser G over to the wire from biz ing post No. 3 at any convenient pom See Fig. 6. Be sure that the condem G is connected with the jack side of coil, for if you connect it with thew side, the receiver will not work at al Coil D can be connected with s denser F, the lower terminal going ¢ stator plates, and the upper termina the rotary plates. ae Now you are ready to place eoil AJ position. Connect the lower termi of B with the rotary plates of the denser FE, and the upper terminal wi stator plates of the same condenser, last two connections are to the antenn and ground binding posts, Nos. 1 from the terminals of coil A. You will note that no instructions } been given as to the direction of th winding of the coils with relation to ead other. It makes no difference which ¥w; they are wound. Likewise, the spe terminal connections to transformer J have not been given, for it is well, in thi circuit, to try reversing the primary nections to this transformer. In many reflex circuits there are @ number of factors that may spoil if operation.. In this set there is just ong! point to watch out for, and that is the number of turns in coil C. Too man turns will cause the receiver to squeal on the lower wave lengths. Too fewt will make the receiver not sensitive, a an adjustable crystal at W easy to tell when you have e thing right, for the receiver should g¢ continuously when the catwhisker is” in contact with the crystal, and disappear when the _ whisker contact. It might be well to point out here thal any type of crystal suitable for use ind plain crystal circuit will work perfect in this receiver, since the crystal is 0 subjected to the current from the tery. ee The success of the receiver depe to a large extent on a good, se crystal. Therefore, if you use @ 2 crystal, try several before you start alter the number of turns in coil C. | Ninety volts is about right for We B battery, but in actual test, excellemy signal loudspeaker strength was obtained with two 114-volt dry-battery tubes an@ only 48 volts of B battery. ee ] LY © This seal on a radio or tool advertisement signifies the approval of the INSTITUTE OF STANDARDS. See page 33.