$10.50 a month for this 9 x 2' Junior South Bend Back-Geared Screw Cutting Lathe
Weight 325 lbs. Price with countershaft and equip-ment
$1.50
$30 down, $10.50 per month. Also available on 11″ and 13″ sizes, countershaft drive silent chain motor drive, underneath belt motor drive in bed lengths from 3' to 8⅛', both bench and floor leg tpyes. Practical for manufacturing. also service work on valves, bushings, pistons, differential cases, connecting rods and brake drum work on light cars.
13″ × 4′ Model Junior back-geared scre cutting lathe, weight 980 lbs. Handles brake drum work on Ford, Chevrolet and other light cars.
Price with countershaft and equipment $308
$61.00 dtnrn, $21.56 per month.
EASY PAYMENTS ON ALL SIZES AND TYPES Send for new catalog No. 92, illust- ing, describing and pricing new Junior Series South bend Lathes. with details of easy payment plan. Mailed Free. Postpaid.
SOUTH BEND LATHE WORKS
853 E. Madison St.. South Hend, Intliaiin
Lathe Builders for 25 Years - 50,000 South Bend Lathes in Use Make Beautiful CABINET WORK Furniture at 1/10 STORE COST
Our Illustrated Catalog Prices Hundreds of Items
Domestic, Foreign. Lumber —Burl, Crotch, Diamond Matched Veneers — Inlay Woods, Bandings — Many Styles Cared Turned. Fluted and Twisted Legs — Cabinet Hardware — Tools, Machinery and Supplies. SOLID MAHOGANY or Walnut 28″ Turned — Fluted and SANDED Legs 55¢ Each see L-106.
Our large. new 44-page catalog is just off the press. Send 10¢ in coin or stamps to cover postage and wrapping. Cred- ited on first or- der.
Inlay handlings 15¢ a yard up. 20 different woods. ¼″ × 2½″ × 3″ Beautitful asortment all labeled, only $1.00
CRAFTSMAN WOOD SERVICE COMPANY We Ship All Over The World 7354 Vincennes Ave. Chicago, Ill.
BIG FORTUNES WON BY TINY INVENTIONS
(Continued from page 123)
change in order to perfect an invention. Take, for example the Young gas gen- erator. Ten years ago, Daniel J. Young, an engineer of Tacoma, Wash., proposed that, in making water gas, the "run" be occa- sionally reversed; that is, that the steam be run through the generator from the oppo- site end. This idea, greeted with laughter by the gas companies, was tried out, and in less than ten years it was adopted by every gas company in the world.
WATER gas is made by passing steam through a bed of red-hot coal. The oxy- gen in the steam combines with the carbon "in the coal, leaving hydrogen, which is made into illuminating gas by adding hydrocarbon elements from oil. Young's "back-run" proc- ess increases the production of gas from a given quantity of coal to such an extent that about ten per cent of the fuel is saved, or approximately three cents on every 1,000 feet of gas manufactured. Figure that out for all the gas plants in the world! All that is necessary to effect this saving is to pipe the steam into the former exit end of the machine. Part of the secret lies in the conversion into useful gas of carbon deposits which, in the old system, were not only wasted but had to be removed at a price. Last July, the Franklin Institute of Phila- delphia conferred its much-coveted Walton Clark medal on Young for his achievement.
Similar was the famous improvement made by Henry A. Adams in the corn-shelling machine invented by his father, Augustus Adams. In the father's machine, the chute into which the ears of corn were fed was often clogged up, despite the fact that rotat- ing fingers had been provided to push the ears downward. A farm hand usually was needed to clear the chute by punching the ears with a stick. Henry Adams merelv rotated the lingers in the opposite direction, and any corn farmer will tell you that no extra hand is needed today to push the ears down the chute.
Or consider Dr. Langmuir's much-discussed high-vacuum tube patent. In 1925, Lang- muir was granted a patent on a vacuum tube which did not differ in any way from those invented and patented previously, except that it was evacuated to a greater degree. In other words, Langmuir succeeded in subtracting almost nothing from nearly nothing and, in a manner of speaking, pat- ented practically nothing at all!
THIS does not mean that his invention was not useful. Quite the contrary. The higher vacuum virtually eliminated ionization in the tube. Let me explain. The operation of a vacuum tube depends on a flow of elec- trons from a heated cathode, or metal ele- ment, to a plate, which is another near-by metal element. That electron flow can take place only when the number of air molecules in the tube is reduced to a point where the electrons have a relatively clear path. If too many air molecules are present, the elec- trons, moving away from the heated ele- ment at terrific speed, strike these molecules and disassociate or ionize them. This ioniza- tion prevents operation of the tube as an electrical oscillator, just as a steel spring would be prevented from ibrating by wrap- ping cotton batting around it.
Acting as an electrical oscillator is the chief function of a vacuum tube, As devised by Lee De Forest, it forms the basis of all modern radio transmission and reception. By producing a more complete emptiness in the tube, Lang- (Continued on page 125)
Twenty-five Years
—the money from the sale of Christmas Seals has promoted:
— the establishment of sanatoriums for treating tuberculosis
— the finding of tuberculosis in time to effect a cure
— health inspection of school children
— the teaching of habits that help to insure good health
— the bringing of rest, good food, sunshine, fresh air, medical at- tention to sick children
Help Fight Tuberuclosis
Buy Christmas Seals THE NATIONAL, STATE AND LOCAL TUBERCULOSIS ASSOCIATIONS OF THE UNITES STATES
The IDEAL. Falcon
15 in. Models
The IDEAL Bowling
Build Three Models for $1.65
The IDEAL Travelair
Biggest value ever offered Model builders IDEAL 3- in-1 Kits contain everything required to build three, per- fect, full-fuselage Models; all Parts. Fittings and Materials also full-size Plans and In- structions for each Model.
Complete 3-in-1 Kits $1.95 postpaid
Catalogue Models. Parts, Fittings, Supplies and Materials—5¢.
Two Separate Kits: No. 1 Containg: The IDEAL Boeing The IDEAL Travelair The IDEAL Falcon
No. 2 Contains: The IDEAL Fokker D-7 The IDEAL Lockhead Vega The IDEAL Waco Tiger Wing
IDEAL AEROPLANE & SUPPLY COMPANY, Inc. 28 West 19th Street New York City
The Most Beautiful Ship Model Ever
Made— The Barbary Pirate "FELUCCA"
new and now ready, Hull fully shaped and sanded all parts and
accessories supplied cut to fit and ready to assemble.
"You Can Build one" for only $4.50. and postage.
Wonderfully designed and accurately executed, this model, brilliantly colored, is a lasting ornament, and its construction a fascinating pastime. Sent C.O.D. parcel post In U.S. or Canada.
Santa Maria. Mayflower. Covered Wagon or Coach Model $4. 50. Constitution $6.00, Flying Cloud $4.00 or a Spinning Wheel $1.00. Send 2¢ stamp for catalog.
Miniature Ship Models, Inc.
90 King St.. Toronto Dept. NA. (illegible text), Pa.
GEARS In Stock — Immediate Delivwery Gears, speed reducers, sprockets, thrust bearings, flexible couplings, pulleys, etc. A complete line is carried in our Chicago stock. Can also quote on special gears of any kind. Send us your blue prints and inquiries.
Write for Catalog No, 214
CHICAGO GEAR WORKS
769-763 W. Jackson Blvd. CHICAGO. ILL
For Christmas— A Gerstner Tool Box for the machinist and Toolmaker. The appreciated and practical gift.
R. GERSTNER & SONS 596 Columbia St.. Dayton. Ohio . .
LEARN ORNAMENTAL COLOHED CONCRIETE TRADE Learn how to make beautiful One. Piece Cement Fireplaces In any color. effect or design at a cost for materials of less than four dollars
Learn how to reproduce in colored cement, pictures, designs, scrolls, coat-of-arms, etc. , from your own molds.
Lean how to reproduce in culoredcementlhe effect of marble, brick. granite, tile, Travertine, Terrazzo, etc. How to make colored cement garden benches, portable garage blocks, etc. How to do all of the above without the use of any machinery whatever!
The time to act is NOW— write for details of personal instruction or home study course and easy payment plan
ORNAMENTAL CONCRETE INSTITUTE 246 Fifth Avenue, New York, N. Y.
symbol characters) This seal on advertisments signified the approval of POPULAR SCIENCE Institute OF STANDARDS. See page8