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They Quit Laughing When He Got x$5000 Electrical Job Of course a lot of fellows laughed when B. G. Melrose told them he was going to become an electrical expert by twenty weeks' training at home. But Melrose knew. He knew that many other men have stepped quickly into big money success through the amazing Shop Type Training of the S. & H. Engineering Com- pany (Affiliated With the Lincoln Institute of Technology). He filled out a coupon like the one below and that's why Melrose today has a big job paying more than $400 a month.

OU too, c a n fit yourself quickly as in Electricity? quickly for $5,000 to $10,- Every day new men are com- 000 a year positions or your ing to the front -yet they have own big business in electricity been in the field only a few through this amazing training. years. If you are ambitious I know exactly what you need and want a big income before to make you an you are too old to electrical expert. Do Like Unholz enjoy it enter the Train only twenty and Farina Electrical World. WARNING! weeks right in They were common laborers but It pays you big now after taking this amazing THIS TRAINING IS your own home. training they own the big Unholz money for doing COPY- This and Farina Electrical Company, amazing their own prosperous business. I fascinating work. RIGHTED. YOU CAN GET training is c o p y - have shown many men how to step into a big business of their own. BIG FREE IT NOWHERE ELSE. righted and you And the beauty of it is I help can get it nowhere you earn good money even while OUTFIT Remember, this unsurpassed you are taking this quick simple training else. And remem- and easy training. of S. & H. and Lincoln I want you to decide Institute of Technology is ber I'll fit you for f o r yourself. Merely copyrighted. You can get it no- the $5,000 to $10,000 electri- fill out and send the coupon. I'll tell where else. Don't take chances. cal jobs or I don't want one you about the big electrical outfit I Be trained by experts. Fill out penny. will give you free to help you in your the coupon and I'll prove to training. Also I will send you my you that there is no other train- beautiful free book telling you a hun- ing like this. One of America's dred or more things about electricity and the amazing big Greatest Industries money opportuni- Chief Engineer Brown, ties it offers you-things which you S. & H. ENGINEERING CO., In what other field can the 1422 W. Monroe St., Dept. D -2, have long wanted to know. Act at Chicago, Illinois. ambitious m a n succeed so once. Send the coupon to Please send me full particulars of your training in practical electricity and details of your remarkable free offer to those who Chief Engineer Brown enroll now. I understand this is free and obligates me in no way. S & H ENGINEERING COMPANY Name l ffiliatéi with Lincoln Institute of Technology Address 1422 W. Monroe Streát, Dept. D -2, Chicago, Illinois City State

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Science and Invention for April, 1925 1169 LEARN

In Great Shops: Coyne trained Electrical Experts are in demand everywhere- because they are men who are practically trained and thoroughly trained for the Big Jobs in Electricity. Send that coupon to me now and see Earn $60 to $200 a Week! how I fit you for one of the thou- Clip that Coupon Right Now! Get my Big New Book- sands of BIG PAY OPPORTUNI- you. Crammed TIES in 12 short weeks! No IT'S FREE! It points the way to Success for obligation at all! Act quick! full of hard, dependable, proven Facts. Shows the way to Big Pay in the Largest, Most Interesting Money- Making Field -ELECTRICITY! Find out how a world of Opportunities can be opened up for you as a Coyne -Trained GET MY BIG, Electrical Expert. See what my PRACTICAL TRAINING has done for others. Read what they say about Coyne. NEW BOOK I'll Make You An Electrical Expert NOW FREE! IN 12 WEEKS! Radio Send for it now. It's a book worth Yes, sir, I train you for the BIG JOBS You Learn in Chicago & Auto having. Hand- in ELECTRICITY! Coyne IS NOT Course somely bound. A CORRESPONDENCE SCHOOL! I Beautifully Illustrated. Size 12x15 the Electrical Center inches. Shows dozens of actual photo- train you-thoroughly -on thousands of Coyne students F R E E graphs of Coyne students working in of Apparatus. World dollars' worth Electrical of the master Electri- Special Offer my BIG SHOPS. Gives others' You" do ACTUAL WORK on REAL Center of right now! I am experiences. Shows what you you on city right in the Electrical can do. Cost me a dol- EQUIPMENT -the kind use out You see everything elec- including Ab- lar, but it's yours the job. That's why my students the World. solutely F ree trical here. Along with my Shop my Big free if you mail MAKE GOOD. That's why you Mas- New coupon. Do Training you visit the big organiza- R A D I O ter Electricity in 12 WEEKS at Coyne_! their COURSE it now! tions and power plants -learn and AUTO, methods first hand. TRUCK a n d TRACTOR Coyne Trains You E L E C - Earn While You Learn TRICITY. no difference Coupon For Life It makes I back my students up. My Employment brings how little Education or Dept. will assist you in getting a part time full Electrical Experience you have had, job to make a good part of your expenses details. while training. And it will help you get a I'll make you an Electrical Expert BIG PAY JOB on graduating. through Coyne's LEARN -BY -DOING METHODS! I have done it for thou- 26 Years of Success MAI L TH IS GÒUPON ! At sands. I will do it for YOU Remember Covne is a School with an estab- Coyne you get a Life Scholarship. You lished REPUTATION. Endorsed by Elec- H. C. LEWIS, President can stay longer than the required time trical Industry. Over a QUARTER OF A COYNE ELECTRICAL SCHOOL, if necessary. You can return any time CENTURY of Success that was earned by ILLINOIS - the BIG SUCCESSES of Coyne Students. 1300 -10 W. Harrison St., Dept., 533 -4, CHICAGO, later to take up new work I am con You owe it to yourself to find out what I tinually adding to keep my course up- can do for you. Clip the Coupon Now! Dear "H. C. ":- Please send me, absolutely to -date at all times. H. C. LEWIS, President. FREE, your big New Book and full particulars of your Special Offer of Two Extra Courses FREE. H. C. LEWIS FOUNDED President COYNE 1899 ELECTRICAL SCHOOL Warne Dept. 533-4 1300 -1310 W. Harrison Street CHICAGO, ILL. Address

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Vol. XII. April, 1925 Whole No. 144 Il No. 12 r,m,nn1,»aan,nam FORMERLY ELECTRICAL EXPERIMENTER IN OUR NEXT ISSUE Member Audit Bureau of Circulations Did You Ever See EDITORIAL & GENERAL OFFICES: 53 Park Place. New York City a Dinosaur? Published by Experimenter Publishing Company, Inc. (H. Gernsback, Pres.; S. Gernsback, Treas.; It. W. DeMott, Secy). We will tell Publishers of SCIENCE & INVENTION. RADIO NEWS. THE EXPERIMENTER of a new motion picture, and MOTOR CAMPER & TOURIST. "The Lost World," in which huge monsters of pre -historic times return to scenes ii1111111131.111111111111111111111111111 1111111.111M of the present day and devastate country- sides, terrifying the population. We will Co..ICCnic5 for show how these monsters have been produced so that the film shows most realistic POPULAR ARTICLES PRIZE CONTESTS and likelife animals. In this article you Editorial Scientific Humor- Prizes for Best 1177 Jokes will see photos of these creatures chasing By Hugo Gernsbeck. 1233 a Awards in $1000 Monthly Contest 1236 party of hunters and an explanation will Can We Fight War Gas Attacks ? 1178 accompany, showing how the photography By H. Winfield Secor. AUTOMOBILES was accomplished. A Hotel for Bachelors 1180 Axe Marks 25,000 Years Old 1181 An Aerial Taxicab 1184 * * * By Johan R. Howard. Super- Charger for Automobiles 1190 The Battle of Colors 1182 Traffic Mirrors 1192 Will Atomic Energy Ever By A. P. Peck. Be Released? Outdoor Scenes Duplicated in ELECTRICITY Studio 1183 By Harry Van Demark. Hearing Iron Molecules Move... 1191 A prominent Oddities in college professor will pre- An Aerial Taxicab 1184 the News 1193 sent in clear illustrations Mummy Changes Electric Phonograph Motor 1202 and concise de- to Dancer 1185 New Devices scriptive matter the probable The Phantom of the Opera 1186 1204 methods By J. Patent Advice 1244 whereby atomic power Kelly Burleigh. Edited or energy may in Why Some Oysters are Diseased 1188 by A. P. Peck. the future be released and will comment Our Tests with Flettner Rotor 1189 upon the result of releasing this enormous By Prof. Harold F. Rickards, Ph.D. RADIO ARTICLES Super- Charger for Automobiles power before suitable means for control- 1190 The Larmor vs. Heaviside Theory 1220 ling it By J. H. W. Kerston. By Dr. Joseph are devised. Hearing Iron Molecules M. Howard. Move.... 1191 Decorated Radio Panel 1221 * * * Device Locates Life Boats 1191 Single Control Water and Land Receivers 1222 Tractor 1192 By Leon L. Adelman, A.M.I.R E. Can the Sex of Unborn Babies Telescope and Eye Distance Gauge 1192 European Broadcast Oddities in the News Map 1224 Be Determined? 1193 Radio Odds and Ends 1225 The Living Death 1194 Mid -Ocean Radio By John Martin Leahy. Weather Bureau 1225 Experiments by prominent A Four Tube Distance Getter 1226 American Will There Be Another Ice Age ? 1196 By Sidney E. Finkelstein, and foreign doctors point By Dr. Gene Deachem. A.M I.R.E. toward an ulti- The Ritz Super- Heterodyne 1227 mate realization of this point that has Dr. Hackensaw's Secrets 1198 By Charles Caesar Ritz. often been By Clement Fezanditt. A Multi -Range discussed by interested parties. This Month's Latest Devices.... Wave Meter 1228 Our article will 1200 By Sidney E. Finkelstein, A.M I.R.E. deal with the complete Smashing Airplanes for Tests 1201 A Page for the process of determining By Joseph H. Kraus. Novice 1229 the sex of unborn Radio Oracle 1230 babies, giving full details. Electric Phonograph Motor 1202 Thought Needs Blood * * * 1202 CONSTRUCTOR Artist's Copying Appliance 1203 ARTICLES Are You Contemplating New Tile Joint 1203 Making Cactus Lamps 1214 New Devices 1204 Metal Etching 1215 a Vacation Trip? Studies of the Plant World 1205 By Joseph Crotty. Odds and Ends of Physics 1206 A Sensitive Hygrometer 1216 If so, you will undoubtedly desire to By T. O'.Conor Sloane, Ph.D. By C. A. Oldroyd. take a radio receiving Magic for Everybody 1207 Emergency Pulleys 1216 set with you. An By Prof. Joseph By authoritative article in our Dunninger. Alvin Heduall. next issue will MoreGambler's Tricks Exposed 1208 Interesting Paper Models 1216 deal with complete constructional details By Mark Mellen. By A. Grttntal. of an exceedingly compact H. R. H. Prince of Wales yet efficient Astounded radio set. This type of set is 1209 CHEMISTRY ARTICLES =I completely Portable Bedroom Outfit 1210 self- contained with the exception By G. H. Can We Fight War antenna of the Waetjen. Gas Attacks ? 1178 El and ground. All of the batteries Everyday Chemistry 1211 By H. Winfield Secor. are placed within the By Raymond B. Wailes. The Battle of Colors 1182 case and the tubes Surface By A. P. are entirely protected when Tension-Capillary Attrac- Peck. the cover of tion-Cohesion 1212 Everyday Chemistry 1211 -i the container is lowered. By Raymond B. Wailes. By Raymond B. Wailes. Scientific Problems Surface Tension -Capillary The above are just a few of the treats and Puzzles 1213 Attrac- in By Ernest K. Chapin. tion- Cohesion 1212 store for our readers in the next Readers' Forum By Raymond B. issue. `e 1219 Wailes. gnu n 1nmm1111.11., 1111.111,...... mmmumw1111.1111111mm,n,,,,, "...nm n, . ,, ,,,,,,...: ..., .m illI mirtral m .11.1.1.,. . HOW 'ro SUBSCRIBE I`0ß1111 ,,. INVENTION. "SCIENCE'll1 AND CAMPER & TOURIST. Subscriptions may order and remittance Send your name. address and be for a renewal, delivery of mittance to Experimenter Publishing re- made in combination with the other publications the magazine is stopped. Place, New York Co., 53 Park iust mentioned at special reduced club rates. Send CHANGE OF ADDRESS: City. Checks and money orders postal for club rate card. Subscriptions Notify as as far ln ad- should be made Payable to Experimenter start with Vance as Possible. giving your old address as well Co., Inc. Mention Publishing the current issue unless otherwise ordered. as the new one to which future the name of the magazine you ON EXPIRATION of your subscription magazines are to are ordering inasmuch as we also publish we enclose go. It takes several weeks to make an address NEWS, THE EXPERIMENTER RADIO a renewal blank in our last number to M. and change on our records. and MOTOR notify you by mail. Then unless we an mmmmmmmimnumm receive your mnn m,m mm, unmmu mmmnmrmnunmmmmmumunmmm,u,,,...... or1, 1 1131n111111111n1111111111nu1u 111111umnmummum11111. . emu imuu:un.w....m..uunuouumm..0.,...... 1uu11111111n1m1, 11u1111111111om1uu1111. SCIENCE AND INVENTION , 10th is published on the INVENTION, 53 Park Place, New York City, N. Y. Sept. 15, 1924, at Post of each month. There are 12 numbers per Office, Atlanta, Ga., Chicago. Subscription year. Unaccepted contributions cannot be returned unless Ill., Los Angeles. Cal., San Francisco, Cal. price is $2.50 a year in U. S. and full Registered Title sessions. Canada' pos- postage has been included. ALL accepted con- at the Patent Office. Copyright. 1975, and foreign countries $3.00 a year. tributfons are paid for on publication. by E. P. Co., Inc New York. The Contents U. S. tain as well as U. S. stamps accepted SCIENCE AND INVENTION, magazine are copyrighted of this den coin (no for- Monthly. Application and must not be. repro- or stamps). Single conies, 25 cents each. as second class matter made at New York, duced without giving full credit to the A sample copy will be N. Y. with publication. All communications sent gratis on request. additional entry at Long Island .City, N. Y. Post newsstands and contributions to this jour- office, under act of Congress of l the IUnited TSttatesi and rCanada also nal should be addressed March 3. 1879. at Brentano's, 37 Avenue to Editor, SCIENCE AND formerly entered de l'Opera. Paris. - at Jamaica, N. Y. Entered on ber of the Audit Bureau idem New York City of Circulations. General Advertising Western Advertising Representatives Pacific Coast Advertising Representatives Dept. Finucan & McClure Kansas City Advertising Representatives 53 Park Place A.. J. Norris Hill Co. 720 Cass St.. Chicago. Il' Hearst Bldg.. San Francisco. Calif. Republic Building Kansas City. Mo.

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SCIENCE and INVENTION READERS' BUREAU

111111111MMIIM6 Time and Postage Saver IN every issue of SCIENCE and If the advertiser requires any money INVENTION you undoubtedly or stamps to be sent to pay the mailing see numerous articles advertised about charges on his catalogue or descriptive which you would like to have further literature, please be sure to enclose the information. correct amount with the coupon. To sit down and write an individual We will transmit to gie various adver- letter to each of these respective con- tisers your request f r information on cerns, regarding the article on which their products. you desire information, would be quite This service will appear regularly a task. every month on this same page in As a special service to our readers, we SCIENCE and INVENTION. will write the letters for you, thus sav- If there is any Manufacturer not ad- ing your time and money. vertising in this month's issue of Just write the names of the products SCIENCE and INVENTION from about which you want information, and whom you would like to receive litera- to avoid error the addresses of the man- ture, write his name, address and the ufacturers, on the coupon below and product in the special section of the mail it to us. coupon below.

TEAR ALONG THIS LINE READERS' SERVICE BUREAU, S&I 4-25 Experimenter Publishing Co., Inc., 53 Park Place, New York, N. Y. Please advise the firms listed below that I would like to receive detailed information on their product as advertised in the issue of SCIENCE and INVENTION. 'THIS FORM SHOULD NOT BE USED FOR TECHNICAL QUESTIONS If Catalogue of complete ADDRESS List here specific article on NAME is which you wish literature. line want- (Street- City- State) ed, check in this column.

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Falling Hair Stoppei New Hair Grown In 30 Days- Or No Cost PRO OF! Results Gi Edifying By ALOIS MERKE "Ten years ago my h air started falling. I used hair tonics constant y, but four years ago Founder of Famous Merke Institute I displayed a perfect full moon. I tried every - New York thing -but without resu ts. Today, however. Fifth Avenue, thanks to your treatmen t I have quite a new crop of hair one inch lc ng. "-F. H. B., New is electricity without the York. SAVE yourself from baldness! No where there Hérr Aboi t Gone hair is fall- slightest discomfort or inconvenience. "My hair has been fa Bing for the last two matter how fast your years and I had hardly any more hair on the ing out matter how little of it is front of my head. But since I started using -no Positive Guarantee your treatment I am r ising a new crop of now left -no matter how many treat- hair. Your treatment 1 best I ever saw. " - Of course there are a few cases of O. J., Northbridge, Mas ments you have tried without results- baldness that nothing in the world can Falling Hail Checked I have perfected a new scientific sys- cure. Yet so many hundreds of men "My hair was coming c ut at an alarming rate, tem that I absolutely guarantee will but after four or five to atments I noticed this and women whose hair was coming out was checked. My hair is coming in thicker give you a new head of hair in 30 days and looks and feels full of life and vigor. "- almost by "handfuls" have seen their Neck, L. I -or the trial costs you nothing! W. C., Great hair grow in again as the shrunken roots Hair Growing many years re- New I have found during acquired new life and vitality that I am "Results are wonderful . My hair has stopped from experience gained in at falling out and I can sec lots of new hair com- search and willing to let you try my treatment ing in. " -F. D. R., Wa: hington, D. C. of cases of baldness if you are treating thousands my risk for 30 days. Then New Hair on Bald Spots at the Merke Institute, Fifth Avenue, not more than delighted with the new "I have used Therm cap Treatment for 8 loss hair to me weeks and although the t 'p of my head has been N. Y., that in most cases of of growth of hair produced, write entirely bald for 6 year the results up to the roots are not dead-but merely immediately. Tell me my system has present are gratifying. In fact the entire bald the spot is covered with a f ne growth of hair. "- dormant. not done what I said it would. And W. C., Kenmore, Ohio. the 30 -day trial won't cost you a cent. En( ugh For It! is useless and a waste of time and Can't Say It "Am glad to say I car see such great change money to try and get down to these Tells All in my hair. It is growi g longer and my head Free Booklet is full of young hair t hat has made its way under -nourished roots with tonics, mas- through since I have bee using Merke Thermo- The very fact that you have read this say enoui h for it. It will do oil, etc., etc., for such meas- cap. I can't sages, crude announcement shows that you are anx- everything you claim it to do. " -G. G., Texas. of the skin. ures only treat the surface ious about the condition of your hair. But my scientific system involves the So why not investigate? Find out for only common -sense application of entirely new principles in yourself. That's the Inc., fill in ALLIED MERKE INSTI1 UTES, stimulating hair growth. It penetrates thing to do. If you will merely Dept. 464, 512 Fifth Ave. New York City. below the surface of the scalp and gets and mail the coupon I will gladly send cost or obligation a won- Please send me- without cost or obligation-a right to the cause of most hair troubles you without to Grow Hair," which de- copy of your book, "The New Way -the starving dormant roots, and pro- derfully interesting booklet describing the Merke System. vides not only an efficient way of reviv- scribes in detail my successful system ing and invigorating these inactive roots, which is growing new hair for thou- Clip and Name but of giving them the nourishment they sands all over the country. (State whether M ., Mrs., or Miss) need to grow hair again. And the fine mail the coupon today. Allied Merke thing about my system is the fact that Institutes, Inc., Dept. 464, 512 Fifth Address it is simple and can be used in any home Avenue, New York City. City Mate

www.americanradiohistory.com 1174 Science and Invention for April, 1925 BUSIED TREASURE can still be found in CHEMISTRY Good Chemists Command High Salaries and you can make yourself What Some of Our Students Say of This independent for life by un- Course: I have not written since I received the big earthing one of chemistry's set. I can still say that it far exceeded my anticipations. Since I have been studying with your school I have been appointed chemist for yet undiscovered secrets. the Scranton Coal Co. testing all the coal and ash by proximate analysis. The lessons are helping me wonderfully, and the interesting Do you remember how the tales of pirate gold used to fire way in which they are written makes me wait patiently for each lesson. -MORLAIS COUZ- your imagination and make you want to sail the uncharted ENS. seas in search of treasure and adventure? And then you I wish to express my appreciation of your prompt reply to my letter and to the recom- would regret that such things were no longer done. But that mendation to the General Electric Co. I in- is a mistake. They are done -today and everyday on tend to start the student engineering course at -not the works. This is somewhat along electrical desert islands, but in the chemical laboratories throughout lines, but the fact that I had a recommenda- your own country. Quietly, systematically, tion from a reliable school no doubt had con- the chemist works. siderable influence in helping me to secure the His work is difficult, but more adventurous than the blood- job. -H. VAN BENTHUYSEN. curdling deeds of the Spanish Main. So far I've been more than pleased with Instead of meeting an your course and am still doing nicely. I hope early and violent death on some forgotten shore, he gathers to he your honor graduate this year. -J. M. T. O'CONOR SLOANE,` wealth and honor through his invaluable contributions to hu- NORKUS, JR. .B. A.M. LL.D. Ph.D.Ph.D I find your course excellent and your instruc- /A manity. Alfred Nobel, tion, Noted Instructor Lecturer and the Swedish chemist who invented truthfully, the clearest and best assem- Author. Formerly Treasurer Ameri- dynamite, made so many millions that the income alone from bled I have ever taken, and yours is the fifth can Chemical Society and a practical his bequests one I've studied. -JAMES J. KELLY. chemist with many well known provides five $40,000 prizes every year for the From the time I was having Chemistry it achievements to his credit. Not advancement of science and peace. C. M. Hall, the chemist has never been thus explained to me as it is only has Dr. Sloane taught chemis- now. I ant recommending you highly to my try for years but he was for many who discovered how to manufacture aluminum made millions friends, and urging them to become members years engaged in commercial through of such an organization. -CHARLES BEN- Chemistry work. this discovery. F. G. Cottrell, who devised a valu- JAMIN. able process for recovering the waste from flue gases, James I shall always recommend your school to my Gayley, who showed how to save enormous losses in steel friends and let them know how simple your les- manufacture, L. sons are-C. J. AMDAHL. H. Baekeland, who invented Bakelite-these I am more than pleased. You dig right in are only' a few of the men to whom fortunes have come from the start. I am going to get somewhere with this course. I am no glad that I found through their chemical achievements. you. -A. A. CAMERON. I use your lessons constantly as I find it more thorough than most text books I can secure. -Writ H. TIBBS. Now Is the Time to Thanking you for your lessons. which I and not only clear and concise, but wonderfully interesting. I am-ROBT. H. TRAYLOR. Study Chemistry I received employment in the Consolidated Gas. Co. I appreciate very much the good Not only are there boundless opportunities for amassing service of the school when a recommendation I wealth in Chemistry, but the profession affords congenial was asked for. -JOS. DECKER. employment at good salaries to hundreds of thousands who merely follow out its present applications. These anon- cations are innumerable, touching intimately every business and every product In the world. The work of the chemist can hardly be called work at all. It is the keenest and most enjoyable in a kind of pleasure. The days chemical laboratory are filled with thrilling and delightful experimentation, with the alluring prospect of a discovery that may spell Fortune always at hand to spur your enthusiasm. ' You Can Learn at Home % To qualify for this remarkable calling requires elaborate specialized necessary training. Formerly it was to attend a university for several years to acquire that training, but thanks to our highly perfected and thorough system of instruction, you can now stay at home, keep ' your position, and let us educate you in Chemistry during your spare time. Even with only common schooling you can take our course and equip yourself for immediate practical work In a chemical S INSTITUTE laboratory. Dr. Sloane gives every one of his students the same careful, personal supervision that made him celebrated throughout his long career as a college /OF NEW YORK instruction from professor. Your the very beginning is made interesting and practical, and we supply you Home Extension with apparatus and chemicals for performing the fascinating analyses work and experimental Division 4 that plays such a large part in our method of teaching, and you are awarded ' the Institute's official diploma after you have satisfactorily completed 66.5 -West Broadway Experimental Equipment the course. New York City Easy Monthly Payments fle Furnished to Every Student You don't have even Please send me at once, have to the small price of the course to start. You can without any obligation on my We give every charge Day for it in small monthly amounts -so small that you won't feel to student without additional this The cost of cur course very them. part, your free Book "Opportuni- chemical equipment, including forty -nine pieces of labora- is low, and includes everything, even the 'ties for Chemists," and full - par tory apparatus and supplies, and forty different chemicals chemistry outfit-there are no extras to buy with our course. Our ' of monthly places plan ttculars about the Experimental Equip - and reagents. These comprise the apparatus and chemicals payments a chemical education within the reach cf ment given to every student. Also please everyone. Write us and let us explain our plan in full -give us the ' used for work course. The the experimental of the fitted of you S tell me about your plan of payment and heavy wooden box serves not only as a ease for the outfit opportunity showing how you can qualify for a highly trained your special 30 day offer. but also as a useful laboratory accessory for performing technical position without even giving up your present employment.'S countless experiments. Special 30 Day Offer Besides furnishing the student with his Experimental Equipment, we are making an additional special offer for NAbIE a short while only. You owe it to yourself to find out CHEMICAL INSTITUTE it. Write today for full Information and free de book "Opportunities for Chemists." Send the coupon ; right now while it is fresh in your mind. Or just 'ADDRESS OF NEW YORK, Inc. write your name and address on a postal and mail Home Extension Division 4 it to as. But whatever you do, act today before this offer is withdrawn. 66,S-WEST BROADWAY NEW YORK CITY DON'T WAIT -MAIL COUPON NOW! 'CITY STATE ,S.I.,Apr. 23

www.americanradiohistory.com Science and Invention for April, 1925 1175

3500tJ1OOOOaYcar is Easy toEarn in ELECTRICITY!! Hundreds of my students are earning this big money holding down big electrical jobs and in business for themselves. You can do it, too. My 16 big guarantees of satisfaction guarantee your success. Never before was there such a demand for electricity and so many trained men to handle it as there is now. $75 a week is just an ordinary salary. $100 a week and even $200 is easy when you are properly trained-trained as I will train you right in your own home. Step out of your small -pay, no- future job. Be a "Cooke "Trained Electrical Expert, for "Cooke" Trained men get the big jobs in Electricity. Big Jobs My 16 Big Open to You Guarantees In Radio Work, Power Plants, Con- I give you 16 definite guarantees READ the Proof tracting, Automotive Electricity when you enroll for my Course, in- everywhere. The biggest jobs are- cluding a signed bond to return from My Students open to "Cooke" trained every pennyyou pay me men. My employment if you are not satisfied. $30 to $56 a Day in bureau sees to that. I Use My Money These guarantees cov- am actually spending Go FREE Consultation Business for Himself over $25,000 a year just to Into er J. R. Morgan, 36 to get jobs for my stu- Busines s for and Employment Serv- PrescottSt.,Colum- dents. Yo arself ice, FREE tools, FREE use of laboratory, bus, O., formerly Every montth I start a $4.50 a day me- I Can of my st adents in FREE Engineering chanic, now aver- business f or them- Magazine and other ages over $40 a day things previously un- doing electrical Train You selves. I gi ethem all work on his own the money they need heard of in home study hook. help them g et started training. I spare no ex- Better and helpthe mtoabig pense to make you a Being a college trained success. G et the de- success. Earns $800 in 23 Days engineer with 25 years tails of th is great big and quick of practical experience, offer from my big Earl R. Montrose, and now Chief Engi- FREE book Mono Lake, Calif., neer of the great Chica- Investigate gets electrical con- go Engineering Works, tract, completes it a Million Dollar Institution, I know Dig exactly what kind of training you - Get Proof - in 23 days and col- need to succeed in this big profes- lects $800 profit. sion. That's what I give you-practi- Electrical Book cal training by a practical man -the a Year Front kind of training big electrical com- FREE! $7,000 panies are looking for and are will- You want proof! You want facts! Electricity on the Farm ing to pay for - the kind of training These I give you ini my big book- you will need to be successful in The Vital Facts Herbert Dickerson business for yourself. About Electricity" - used to earn $30 a proof that opportu- week. Now super- nities more wonder- a a _. intendent of Elec- Earning ful than you ever L. L. COOKE, chief trical equipment at Start dreamed of await you Engineer. Chicago proof that "Cooke" Engineering Works, NorthWales Farm, Money Once - Dept. 24 Va., at at Trained Men do get 215 Lw Warrenton, You canturn mytraining into money the big jobs in Elec- SvÁpe, $7,000 a year. quickly with your seventh les- tricity and that I can send me your book, "The Vital -begin About Electricity," full son. I give you FREE a whole outfit do more for you than IlloFactsparticular. of your Home Study Makes $75o in Spare of tools and electrical apparatus and anyone else. Send for p Course, and your sixteen guarantees, o Ìadiuugg pian for Thus show you how to get and how to do my new book now. putting atud,nta"in euaine... This spare time jobs. You make several Be a "Cooke" Trained t obligate me to euroS for Before completing times the monthly payments for my Electrical Expert - your Coursa. course, John J. Burke. Course, and get real, valuable, prac- Earn $70 to $200 a 3332 East Baltimore tical experience. "Cooke" training week. Mail the cou- St., Baltimore, Md. pays its own way. pon NOW? Name made $750 doing odd electrical jobs in ' spare time. Now runs L. L. COOKE, Chief Engineer his own big business. These are Just a Few Chicago Engineering Works Addrees ® Hundreds! Dept. 24, 2150 Lawrence Ave., Chicago Cite State e

www.americanradiohistory.com 1176 Science and Invention for April, 1925

Master Electricity By Actual Practice The only way you can become an expert is by doing the very work under competent instructors, which you will be called upon to do later on. In other words, learn by doing. That is the method of the New York Electrical School. Five minutes of actual practice properly directed is worth more to a man than years and years of book study. Indeed, Actual Practice is the only training of value, and graduates of New York Electrical School have proved themselves to be the only men that are fully qualified to satisfy EVERY demand of the Electrical Profession. The Only Institution of the Kind in America At this "Learn by Doing" School a man acquires the art F of Electrical Drafting; the best business methods and experience in Electrical Contracting, together with the skill to install, operate and maintain all systems for producing, transmitting and using electricity. A school for Old and Young. Individual instruction. Over 9,000 Graduates are Successful Men in the Electrical World No previous knowledge of electricity, mechanics or mathematics is necessary to take this electrical course. You can begin the course now and by steady application prepare yourself in a short time. You will be taught by practical electrical experts with actual apparatus, under actual conditions. The N. Y. E. S. gives a special Automobile Ignition Course as an MerMra facr advanced training for Auto Mechanics, Garage Men and Car Owners. liirus The course covers completely all Systems of Ignition, Starters, Lighting ,. . and other electrical equipment on automobiles, motor boats, airplanes, etc. Let us explain our complete courses to you in person. If you can't call, send now for 64 -page book -it's FREE to you. New York Electrical School 29 W. 17th St., New York, N. Y. Please send FREE and without obligation to New York ¡ne your 64 -page book.

NAME STREET Electrical School. .CITY STATE 29 West 17th Street, New York

www.americanradiohistory.com .11MMTITII111111,1711Tal,::m:.:::::::::::::..1::::::::::::,::::::1 .:...::.....:::::::::::::.11:::::,:::::::::::::,,:,:10-7::11m:,m.,.»,

April, 1925 Volume XII No. 12 Whole No. 144 mu::w»:w.::: :: 1.1 .:n:::,J:nwM, IIIIIM 1I

H. GERNSBACK, EDITOR AND PUBLISHER H. WINFIELD SECOR, ASSOCIATE EDITOR T. O'CONOR SLOANE, Ph.D., ASSOCIATE EDITOR Editorial and General Offices, - - - 53 Park Place, New York .:,::,, ::::::::m "Those Who Refuse to Go Beyond Fact Rarely Get As Far As Fact" - - - HUXLEY t e S.(tui o ent y HUGO GERHS ACK RECENT newspaper report quotes a takes real brains and good training to construct well -known college professor as saying a set yourself and operate it. Almost any one that Radio is acting as a detriment to can read a book and study it, but not every one school studies. The professor ventured to say can master the intricacies of radio circuits. Not that he had observed that a great many students, only does radio give the student an electrical and as well as younger boys still in school, were mechanical education that later will prove most neglecting their studies due to radio. We have valuable to him, but, on the other hand, it will heard arguments against ra- also give the student a man- ni dio, but this one is so novel ual training that later on may I I BELIEVE BELIEVE and the eminent professor is prove a big asset. THAT: THAT: so serious about this conten- A radio set builder must be The boy Radio Ex- Radio will be one tion that we find it necessary a carpenter, an electrician, a perimenter of today of great assets is tomorrow's radio the to discus s the matter at metal worker, a tinsmith, and manufacturer. of humanity. length. a radio engineer, all rolled in- The professor makes the to one. We know of no study contention that the students sit up all night long where more varied acquirements are involved trying to receive long distance messages or oth- than in radio. erwise fritter away their time, becoming unfit Suppose a student does sit up into the early for their work the next day. He recommends hours of the morning with his set. At least he to parents that all radio apparatus should be derives a benefit from doing so, much more so, kept under lock and key while there is a young to our minds, than spending the same amount of time in studying Latin, that may boy in the house. .,,::,:::::::1:::1::1::1:::::11 ::::.:::::::::::::0,::::,:,1:::::::::11,_ To begin with, it is perfectly true never do him much good in later years, that boys do sit up at times until the unless he aspires to become an attorney I BELIEVE the DX radio wee hours in the morning, trying to THAT: or a doctor. One thing It is aspirant learns and that is geography. receive cherished DX stations. Radio, by bringing also true that they occasionally spend Some of the greatest minds in the nations into closer had a good deal of time constructing sets, relations, will pre - radio industry today are those who but the good professor forgets that they vent many wars of the tenacity of purpose and backbone do not do this night after night, but the future. to sit up all night long, experimenting rather do it occasionally. And, after all, with radio, which gave them an educa- night study, whether it be radio, or tion which they could never have ob- geometry, seems to be about in the same class. tained in any other way. The good professor will not deny that when he While we do not recommend young men to was a youngster he burned the midnight oil dispense with sleeping, spending night after more than once. And what is the difference night with their sets, still we do say that an occa- whether you study radio and sit up with it, or sional nocturnal effort of this kind is rather to study arithmetic, or Latin ? be encouraged than otherwise. Personally, we make the con- The crime of the world is THE GOLDEN AGE OF idleness. boy devoted to tention that, if anything, radio SCIENCE The study, radio will be all astir and his should be the preferred is now symbolized by the golden = new mental activity will make for the following reasons : To cover of SCIENCE & INVEN- begin with, there is nothing TION, LOOK FOR THE GOLD him a better student than ever that sharpens the wits of a COVER every month! of arithmetic and of the whole young man as does radio. It school curriculum. 1177

www.americanradiohistory.com 117 - Science and Invention for April, 1925

(4, e Il Brig. Gen. William Mitchell, Army Air Service, says helpless under an By H. WINFIELD

2 DIRECTION OF- ,s WIND

;.F - [ a<-a.r !;% 'yi `5 .

When the wind is favorable, a battleship at sea could lay a gas attack as shown.

'ROÒF. :NÓT.GOOD:IN CAS ATTACK.:. -GAS- :LAYS: ON .ROOF.: ON W I N D L E S S DAYSD A V S

f, -

Poison gas collects as in Fig. 2: heavy at i,11111111»i111mumm111mrrmr. ground level and thinner higher up. ii

,. Ji,ie ,/ SUBWAYS AND CELLARS . ni UP BAD: HEAVY GAS FILLS nS'/ SUCH PLACES UN LESS ALTHOUGH the other powerful nations CLOSED OFF WITH WET of the world are proceeding as usual BLANKETS __' in the construction of battle planes and other aircraft, the United States is falling far ©1925 BY SCIENCE AND INVENTION behind. According to Brig. General William FIG.3 Mitchell, New York, the greatest city of the United States and the most important seaport, is defenseless against an aerial attack. Only 19 planes in the United States today are fit to fight, and the General says ® that because of their age and condition he BOMB CARRYING ZEP. would not be responsible for ordering out 2 any one of these planes for active battle service. He furthermore states that com- SH.1r1.5 mercial aviation in the United States is practically at a standstill, whereas in other countries that branch of aerial navigation is pro- gressing with leaps and bounds. In the particular case of New York City, a fleet of large battle planes could quickly annihilate every living being. As shown in Fig. 2, gas could be spread over the entire AIRPLANE -7!!'i1f4- SUBMARINES THROW- ING CARRIED city by any of the methods indicated in 1 GAS, - CARRIER - Fig. 3. The gas would settle in the cellars '' .. SHOREWARD BY WIND and subways and would penetrate every building. Every line of transportation would - be completely tied up, and as New York City Various agencies could be used by enemy powers for attacking United States cities with gas. is entirely surrounded by water, the millions These are shown above and consist of airplanes and Zeppelins carrying gas-bombs. battleships of inhabitants could not leave the city quick- firing gas- containing shells and submarine evolving clouds of gas to be carried shoreward by ly enough to prevent enormous loss of life. favorable winds. Any of these agencies could quickly make even the largest cities uninhabitable. Our aerial defense needs stimulating.

www.americanradiohistory.com 1179 Science and Invention for April, 1925

ENEMY BOMBERS.... (6 20,00O FT. WC G tt cc ? (OUT OF RANGE) Assistant Chief of the that we would be kk+ aerial gas attack. FYG.4 SECOR

FIG.5 ,I ARTILLERY ALSO WILL FIRE SHELLS CONTAINING 0 ALL THESE ELEMENTS AND l' DEMOLITION AND DISEASE GERMS BLIGHT GERMS ANTHRAX POI50N INCENDIARY SPREAD BY TO DESTROY OTHER GERMS SLAY HORSES GAS BOMBS SHELL ANODE/MD CRO PS ,TREES ro 1 I ETC. AND CATTLE I I e THE MA5 ER ., 1 WARRIOR OF , NEXT WAR + )--j - Irifl ; I',:ïill 1)=T? ; i 10,000 To OMBS I ,; I I 13,000 FT. 1 BUR STING Undoubtedly the master warriors of the next war will be giant aerial bombers capable of carrying several SHRAPNEL tons of gas -bombs and other death -dealing projectiles. Various types of these shells and their purpose are BARRAGE illustrated in the above drawing, Fig. 5. Even the animals will not be spared in the next war. They will be given special attention in the form of germ bombs. I FIG.0

GAS BOMBS - DIRECTION OF WIND

In the event of a poison gas attack, an open plain is the safest place. The wind diffuses and weakens the gas as in Fig. 6. Giant bombers of the future will wreak havoc on cities from a height of 20,000 feet, far the present range of anti- aircraft guns as shown in Fig. 4. above Thirty planes, each carrying one ton of gas bombs could gas an area of one square mile, see II covering most of Central is going NEwYORI, Fig. 7, UNDOUBTEDLY the next war ó= I(1- Park or as in Fig. 8, the finan- fought in the main with in lower New York to be one rS cial district poisons and aircraft. Foreign powers have 7 (=1=1QUUi Q City. in the recent past made and are still mak- 7 Q t ing far -reaching experiments with various 3oco of poison gases. Furthermore, one types CENTRAL FINANCIAL foreign nation has at least two thousand five DISTRICT peace -time ser- =1=o hundred airplanes in active ==o f four thousand eight hun- C- vice and possibly ABOUT C dred other planes in reserve. Contrast this =cr?óó 93DST. with our nineteen battleplanes and our very r--i :. Ci r :, ;° few serviceable observation planes. Suppose E'-I partl.l:. . that the above -mentioned foreign power , ,,_,l SQUARE JCl1 Q a were to declare war on us and establish an s+ ; MILE air base on o. near this continent. Two t¡ ,,L thousand of her planes, each carrying a quar- i :' five hundred G= ter of a ton of gas, could drop öooa öä n" í9 - _yì]O tons of death-dealing material. Such a fleet Ci of planes could wipe out any of the large 1=3 I 100 cities of this country in record time. And !RE! the tragic part of this whole story is that =

a city would probably I inhabitants of I the J have no knowledge that an attack was being I A Ei :L GaC .I. Itt=1QC made until they felt the effects of the gas. 1:4¡[ -ICi c This would be particularly true in the case = Ccloc C nICc,I = of gas bombs dropped outside of city limits, C so that the clouds of poisonous material shall CI C Ó , by wind. =_-.II__I=1Ili be blown toward the habitations 9 H The effectiveness of gases is increased by `-.'n ET T and pene- -=r= the fact that they hug the ground [-= C11=1C CIÇII trate cellars, subways and coal mines. C C t- I = I 2 7CÇlil=_Ii_ CiCIC C = ,,Q w..M

www.americanradiohistory.com 180 Science and Invention for April, 1925 iroT )85aePaeor5 By L. SCHUMACHER

Above: The .ayout of th Foci in tirs newly designed hotel for single men and women. An open air gymnasium and swimming pool are provided. Note skylights for studios.

An interior view of proposed bachelors' hotel may be seen on this page and gives a very good idea of the compact yet dignified arrangement of the fixtures and various luxurious appointments. A large well -lighted reception hall is provided on every floor. Each "suite" consists of a room ten feet square into which space is built every convenience that a person living alone could desire. At one end of the room is found a wardrobe, a complete kitchenette occupying a space only 2' x 2%', a lavatory 2/' x2 /' and a shower bath 2/' x 3'. The floor of the latter is tiled and sloped towards the wall where an outlet pipe is provided for allowing the water to run off. The wash basin is hinged so that it may be swung over the toilet and drained. A complete ventilation system is installed in the walls and the kitchenette is so arranged that vapors arising therefrom are removed CULLAVSiBLE 13L0, through the ventilator. Plumbing costs are reduced by installing the equip- ORESSETd TYPE wITN ment for adjoining rooms against the same wall. SuntNG TRAYS FOR TYPEWN.7Tf12 ETC..

CUT -. PLUMBING COST TO :L( "=1 t. MINIMUM BY SETTING QUIPMENT IN PAIRS

SUCTION VENTILATOR DRAWING VAPOR ANO AIR FROM OATH, WASH. 4 ROOM ANO KITCHENETTE

.HOWE17

CUPI3OAiLD

KITCHENETTE i TRUNK SPACE

-1 WASH ROOM .TOILET FLUSHED 8Y OPENING BASIN STOPPER

The bed, dresser and desk are all combined in this one room apartment and the details of the same may be seen in the insert at the left above. The methods of folding this combination are all indicated. The various articles of furniture in this hotel may be ` made either of wood or of enameled pressed steel in various artistic effects. 025 ,1'e1!_t'C,E ANt 1 h'{,L v i!n!4'

www.americanradiohistory.com Science and Invention for April, 1925 1181

Ame Mat-Rs 25, 00 ireara By JOHN R. HOWARD, Reporter No. 5058

A short time ago the writer of this article discovered a The eyes of tht entire scientific world have been cedar tree twenty -eight feet below the present existing turned toward Los Angeles as the finding of five this fossil is shown in the this ground. A photograph of prehistoric remains of man have shown sec- hand corner of this page. The remarkable United to have been inhabited upper left tion of the States part of the photograph is that it bears unmistakable 25,000 years ago. These fossils are as old as those evidence of implement marks, which were made as illus- race of and were found in of the Aurignac Europe trated above. Below is a diagram of the periods of man the quicksand of the Pleistocene period. The eras the American fossils fossil showing in which European drawing below shows the location of the tree. would fall.

ROMAN EMPIRE -IRON AGE IALLUVIUM 5008.0 - BRONZE AGE ALLUVIUM RECENTTIME E -COPPER FOSSILS FOUND MOWINGNEOLITHI WOULD FALL WITHIN 4,000 B.C. THIS EUROPEAN ERA 7,000 B.C. NEW STONE AGE SAND GREEN CLAY POST. PLEISTOCENE ( 7,000 B.C. F,9 Ft (POSTGLACIALLAKES) 0 N. PALEOLITHIC OR 25,000 B.C. OLD STONE AGE SANDS CARB MAT. 1 LAMINATED 25,000 B.C. ÁÚqU16NñQNAN -CRO- MAGNON MAN 1 SAND -- MOUSTERIAN NEANDERTHAL MAN CARB.MAL ACHEULIAN - I RIVER WASH QUATERNARY lj'0,000 B.C. CHELLEAN PILTDOWN MAN MICA SAND O PLEISTOCENE B.0 t75, MESUINIAN HEIDELBERG MAN 30 jTS,000 BC. FT, GREEN CARBONIFEROUS CLAY 5'00,000 B.C. MATERIAL (SANDY) PITHECANTHROPUS ERECTUS HUMAN PLIOCENE OR TRINIL MAN MILLIONS FOSSILS MIOCENE DRYOPITHECUS (EGYPT) TERTIARY OF OLIGOCENE LOCATION OF HUMAN FOSSILS JUST FOUND YEARS UPPER EOCENE 11 CROSS-BEDDED SANDS r l 1 / /n

G Iwç FI/ THE TREE -0. ''' i,, - l e. . ?``w / / ò,'i' ; p:'Vy, I' 1r r ' !,., - I/... 1r.V I / `\\F\ \ .`i-? i i \.,.'JLl/, K ., i i _ °,%i E--' 7 4 _ 4'__ ,.;J. ?/ 7 ` LOCATION OF FOSSIL TREE ILLUSTRATED ABOVE' DRYOPITHECUS PITHECANTHROPUS HEIDELBERG MAN PILTDOWN MAN NEANDERTHAL MAN CRO-MAGNON MAN OAK-APE ERECTUS (AMERICAN MUSEUM OF NATURAL HISTOIIYL

GREAT SABRE-TOOTH TIGER- SMILOOON (PLEISTOCENE)

ACHEULIAN AXES - - MOUSTERIAN AXE HARRIS HAWTHORNE WILDER, Ph.D AMERI CAN ANIMALS OF THE 5 GIANT SLOTH CAMELS WOLVES MASTODON PERIOD 019Z5 BY. SICIENCEAI0 INVEINrIoN

On this page are also shown the development of the face of man and the development of man's BISON e-` weapons. At the time when this tree was alive the animals shown here also roamed the plains. r

www.americanradiohistory.com 1182 Science and In-i rntion for .1 pril, 1925 The 163zffi e Oo T .ahe CO-OT By A. P. PECK

ONE of the most brilliant effects that has ever been produced on any stage is that presented by Max Teuber in The Vanities. Mr. Teuber is the only originator of chemical optical stage effects in the world today. Our cover illustration gives some idea of the beautiful effects produced on a translucent screen by the color -battle projector illustrated in the c."p upper right -hand corner of this page. The various other apparatus beside the . .,.. .! - f" color projector is used in connection with other parts of Mr. Teuber's production and are illustrated in use below. The projector at the extreme left produces an effect of water waves. Our center illustration shows how the battle of colors is projected on the NOTE BOTTOM screen. Usually one projector, but OF SEA PRINTED 1-1E COLOR ESATTLE occasionally two are brought into play. ON GLASS UPSIDE A from an incandescent bulb or DOWN light HOW COLO',"PROJEGTOR PUSH other source is concentrated through EACH OTHERAIOUND SOUTH AMERICAN 44 ON SCREEN lenses and reflected by mirrors through TRANSPARENT FISH `, a glass bottom receptacle to an.rther mirror set at an angle which throws the light upon the back of the screen. Mixtures of aniline dyes and some oily vehicle are then FISH IN LOWER ejected from syringes upon the surface of the water in the COMPARTMENr container as shown, one color being placed at a time. These colors when freshly prepared do not mix with each other, MIRROR but perform weird gyrations on the surface of the water, t SYRINGE FOR COLORS thrusting each other aside and producing a veritable battle. r- SV i At the left of our center illustration is shown how fish s may be projected on the screen in combination with the MIRROR.*' TRANSLUCENT color battle. These fish are also used as shown in a square SCRE.EN glass tank on the face of which is painted a sub -sea scene. LENSES / This tank is placed in front of a projector and a beautiful fa. effect produced on the screen. Another beautiful effect is the shadow of a (lancing girl projected on a translucent screen. The use of chemicals as shown in the lower right -hand corner of this page shows the dancer moving through a garden of rapidly growing plants. The "plants" are produced by solid chemicals falling through liquids and leaving a trail of color behind.

LIGHTf SOURCE

TRANSPARENT - FLOWER$ AND GRASSES

Above: How a flower garden effect is produced by t method. The flowers apparently wave in a breeze. Below: Another beautiful color effect. A .ight project3r throws the shadow of the dancer on a screen and the dancer appears to be in the midst of a magic garden if strange rapidly growing plan,..

COLORS ON SURFACE CARDBOARD OF WATER Right: How the rapidly growing effect AL,..-40f401. CHEMICALS OR GLASS is produced. A square glass tank on I the face of which is painted a mask is placed in front of a projector as at the extreme right. A layer of pure alcohol is on top of the water and when water or alcohol -soluble aniline crystals are HS TO DEPOSIT dropped in the tank, they sink to the WAIER A VARICOLORED bottom, leaving an arborescent trail of

/DESI/DESIGN ON A GN color after them. The use of a lens PAINTED MASK OR GLASS inverts the reproduction on the screen TANK'S ~r;.. and the colors appear to grow from the CORKED OUTLET bottom to the top. Left : How the battle of colors may be reproduced with tyz5 HYJCfLrd(`]F AND l/Vt'E1YTlO anilines in alcohol or terpentine.

www.americanradiohistory.com Science and Invention for April, 1925 1183 Dtt.pliIlcated Hn. StudIl® b;y BARRY VAN DEMARK LARGE motion picture producers to -day save considerable expense by dupli- casing great ou-door scenes in the studio. Under the old plan, the company was transported tc the location and brought back to the studio for interior work. Now, hol.ev3r. the art directors, designers and creators, photograph a possible scene of locaticn and reproduce it in detail in the studio where powerful lighting efiec-s may be obtained. This development in settings for motion pictures started o1-iy a :ew years ago, :t having been found that back- grounds more neutra: anc less crnate than they used to be give better composition and lend themselves tc morc artistic treatment.

ReFroduction r gig un-ic Buddha ,-atu s.

r _-,-°,.

Typica_ English cottages conatru _ted on Long Island for a recent photoç33y a e shown above.

The background of tie sues_ above might be -he HL3son by moonlight Sc realistic is it. This was produced -a -1-.e studio. Moan, cloud and wave machines w°re used.

The car above is repr-dtcec is detail and is an exact Ready to shoot a Chinese duplicate of the ra1way ayste-n at Monte Carlo. car al constructed in a gigantic tank in the studio.

At the left one may see the members of the research department of a large_motion pictare concern taking photographs of various spots in the South Sea Islands. The one here illustrated is a sort of a wayside inn where dancing takes place ani liquors are served to travelers. The still photographs are then developed ani the duplicate scene is fai: hfully constructed by the art director after all atmos- phereand props have been built in accordance with b specifications. The scene a> ü looks in the modes.

www.americanradiohistory.com Science and Invention for April, 1925 The e Taxicab Left: Colonel Hartney with his improved plane which will make aerial taxis possible. This plane can land in a space 35 feet long at a speed of only 30 miles an hour. The angular wings prevent it from side slipping as shown in the insert at left. The plane is so designed that it cannot lose flying speed and so stall in the air.

Left: -Interior of air taxicab showing conveniences. Below: Automo- bile taxis co- operating with air cabs.

YEC(OWQIRl1E

The improved tail of the aerial taxicab is shown at the 0,' left and direct- improvedly above it the If the plans of Colonel Hartney of the U. S. braces, A, taxi- and Air Service become a reality, aerial the side wing be cabs charging 20c a mile may soon joint, B. quite common. -A. P. Peck. (C)19I4BySe/ENCF a, JNVE/Y7lOX

C uloce of Erupflon5 and inclall Waveo Cap- According to Captain T. J. The reasons underlying tain Sec's is that vol- J. See, earthquakes, tidal theory ESCAPING STEAM +o' canoes are rarely found more waves and volcanic eruptions JJ fis- than 100 miles from a large can be directly traced to VOLCANO sures in the earth's surface body of water. Furthermore, below oceans which connect volcanoes become extinct because the shores build up and with sections of molten rocks OC. As far below the surface as the water seepage to the shown at the right. Steam is molten rocks is stopped. generated which, after col- Where there is no steam, lecting, bursts out of the vol- there can be no volcanic cano in the form of an erup- eruptions. tion.

Below: Shores of con- Below: Proximity of tinents building up. volcano to sea.

MOLTEN ROCKS Above: A fissure through which water seeps, ( reaches molten rocks and forms steam. SHORES BEING BUILT UP T' OAL WAVE SEA PACIFIC OCEAN a `n.

EA SOCTOM SINKS

Occasionally due to eruptions, a section of the sea floor sinks, the ocean rushes Earthquakes on both sides of Pacific cause shores in as shown above, then surges shore- As in lower center illustration, sinking is due to build up and ocean to become narrower. ward in a huge tidal wave. to shoreward mcvement of lava.

www.americanradiohistory.com Science and Invention for April, 1925 1185 nc 4.4a

VERY beautiful illusion is found in This latter version of the illusion is shown while those in back of the plate glass illu- A. Miss Crystal Spencer's dancing act. in the figure at the lower right -hand corner minating the dancer are brought up to full Miss Spencer who specializes in classical of the above illustration. It will be seen brilliancy. The effect is that the object in East Indian and Hawaiian dances is not seen that a plate of sheet glass passes diagonally back of the plate glass has been transformed as the curtain rises. In the center of the from one of the pillars of the back setting from the one in front of the plate glass, stage a large mummy case holding a mummy to the black curtain at an angle of forty - be that what it may. It can be a mummy is in evidence. The body tightly wrapped in five degrees. On one side of this mirror is or a case, or a combination of the two, or bandages now gradually vanishes and slowly the sarcophagus concealed from the audience the case can be placed in back of the plate its features change to those of a dancing but really in front of the plate glass. When glass, so the mummy itself will appear in girl. She comes to life, goes through her the sarcophagus is illuminated, its reflection front of it. The dotted lines in the diagram act and then takes her place in the empty upon the plate glass is seen by the audience, indicate the route taken by the dancer in mummy case again, in which she disappears. the plate glass acting as a mirror because coming to the center of the stage to com- On the other hand, for a slight change in of the black backdrop. Miss Spencer occu- plete her act. In returning, the lights are effect she may be seen in the mummy case pies the position in back of the plate glass, dimmed in the opposite direction and the or sarcophagus which gradually disappears, but she cannot be seen because that side of dancer fades from view. The photo of Miss and she remains standing in front of a dark the apparatus is not illuminated. Gradually Spencer is shown in the insert above. It is velvet background. the lights illuminating the sarcophagus dim, a development of Pepper's ghost. t Laog-the Umbrella There are several styes of these paper or oiled skin hat attachments. They are extremely light and afford ample protection.

The attachment for straw hats The device slips over the straw shown here is a great protection in hat and is held extended by thin rainy or very hot weather. bamboo sticks. It can be folded -L. Schumacher. and put in the pocket. e

www.americanradiohistory.com 1186 Science and Invention for April, 1925

d6 e Phant Tin By J. KELLEY

The enornous size of the sets for tits production may be seen in the above photograph.

Above Chandelier apparently falls. Real:}, it is lowered by a rope.

Above: A beautiful s c en e apparently taken or top of the Paris Opera House. A large, beautiful statue is used, but the rest of the setting is taken as below. Fight: How One of the actors goes under water. A hollow walking stick provides him wi-h air.

One of the highest paid actors on the American screen played the principal rôle in this picture. In the scene illustrated above a "double" took Scene painted on his place. glass furnishes effect of distance.

www.americanradiohistory.com Science and Invention for April, 1925 1187 ®f the perm" BURLEIGH

Move: A «epy n-oment in tb_ picture. A head '.oats alore passze.way. This scene is taken as zt left, bevy ae1agi ng to heat being clothed in black.

THE movie -going public has so long been fooled wish miniature sets by various producers that it is quite refreshing to view some of the tremendous scenes in "The Phantom of the Opera," Jniversal's latest picture. Practically all of the scenes in this production were male full size. The entire Opera House in Paris was completely reproduced, structural steel framework being used. Under the original Opera House there are five cellars, many parts of which were reproduced by Universal. The Phantom in the story is reputed to live in these cellars. He threatens destruction if some of his wishes are not carried out and as a result, the enormous chandelier as in Fig. 2 cashes to the floor. killing hundreds. In reality, the chandelier is lowered slowly by a rope, while the camera is turned very slowly. When projected at normal speed, the result is astoundirg. Throughout the entire picture enormous settings pre- dominate. Note the statuary in Figs. 3, 4 and 9 and the complete Opera House interior as in Fig. 2. Due credit must be given the producing company for its pioneering work along this line. Uncoubtedly, miniatures will soon be passé :n favor of more realistic full sized sets. ne

MIRRORS Above: Some of the full sized sta- MIRRORS tuary teed in this picture. Many skilled artists were used For satisfactorily reproducing famocs works of art. Below and left, Fig. 10: A scene in another torture chamber under he Opera House. Intense heat and optical illusions caused by mirrors soon tend to drive anyone insane who may be confined therein by the Phantom.

During a scene from "Faust," Satan appears on the stage only to vanish again in a puff of smoke, taking with him one of the other characters. Il- lustration above shows the two actors escaping into a trap door, while smoke sufficiently covers their movements to insure an effective illusion.

www.americanradiohistory.com 1188 Science and Invention for April, 1925 Why Seme cyaen-e, ATe DIlesealed

In recent months there has been a general alarm spread over this coun- ing such an oyster is liable to make the consumer ill. The lower left - try relative to the consumption of oysters which may have been in- hand illustration shows a common scene of a restaurant window dis- fected with disease germs. A few facts regarding the methods in playing live oysters and ice. If impure lake ice is used, water from which oysters may collect these germs wilt not be amiss. The upper the ice is liable to enter the molluscs and contaminate them. A home lefthand illustration shows a birdseye view of a river in a cove of experiment showing how oysters are plumped is shown above. Leave which is situated an oyster bed. If sewage water empties into this a few in salt water and a few more in fresh water. After 10 to 12 river and spreads out, there is great danger of the oysters becoming hours, when opened, those in the fresh water will be found much fatter infected. A common practice of oyster growers is to fatten the bivalves than the others. This artificial fatness is abnormal. Oysters left in in fresh water after collecting them from their native salt water. Such cans containing fresh water. presumably to keep them in good condi- a process causes the oyster to swell and often to become "sick." Eat- tion, causes trouble due to unnatural fattening.

LocaIl Nmñn PIliib Finxturfes oNespIlter Moons tf JUPITER'S SHADOW r_, WA TEP COLO A POR - LAOEn

Asheville, N. C., was recently treated to a sight of a strange phenomenon. For TO SUN TO EARTH three minutes with the sun shining W i brightly, rain was precipitated over an Fittings for use where every outlet box can- Jupiter has four moons, but they are not area of six hundred square feet. Sur- not be set straight and where vibrations are always visible. Drawing shows three posi- rounding territory was completely dry. frequent have been produced and are illus- tions where one or more satellites could not As above, co'd air meeting air charged trated above. The device can be aligned so be seen. They would be either in front or with water vapor caused this freak rain- that the fixture will hang plumb while shock in back of Jupiter or in that planet's shadow. fall. -J. Alfred Miller. absorbers take up vibrations. -Allen P. Child. -Ada Weber, M.A.

www.americanradiohistory.com ---11111Men.+.w0

Science and Invention for April, 1925 1189 Ovu- Te5t5 WIlith Filettner Rotor By PROF. HAROLD F. RICHARDS, Ph. D.

::!.!.!..4JI, Mll11JlMp:Ma=.pCM.p1=1.c=1. ,.M111.,.l,:IM'AlieMIlll Measurements made with the apparatus shown in Fig. 1 prove that rough or corrugated rotors would be far more effective than the smooth cylin- has Revolving FRONT VIEW ders Flettner used. the cylinder in the path of an air TURBINE current, the pressure produced by the reaction of the wind on the film of BLOWER MOUTH OF air which the cylinder drags around with it was indicated by the displace- BLOWER ment of water in the Pitot tube. Experiments showed that by reversing the cylinders, the force on the corrugated surface was 4.5 times as great SMOOTH as on smooth cylinder.

CORRUGATED

TURBINE BLOWER CYLINDER

LIGHT LEVEL OF WATER FRAME ADJUSTABLE WHEN CYLINDER IS BALANCE NOT REVOLVING PIVOT WEIGHT GLASS TUBE CONTAINING WATER MOTOR

By fastening the blade of an air turbine to the rotor, but not SCALE revolving the latter, the efficacy of turbine drive was determined. The downward force was greatest when blades were In Fig. 2 we show the precision apparatus inclined to the vertical at an angle of 34° giving a pressure of which tested the claims made for the rotor 4.27 lbs. per sq. ft. of the projected area with a wind speed ship. The cylinder revolved at a surface of 46.6 M. P. H. speed of 59.5 miles per hour and the speed of the wind was 46.6 M. P. H. At beginning of test the frame was balanced horizontally. When wind was turned on, the rotor i,l,i,i,i LI,I,i,IESCALE was forced down and the balance weight moved to the right to bring the pointer back to its original position. Then the wind ADJUSTABLE and rotor were stopped. The BALANCE SCALE cylinder rose and a weight was WEIGHT 4, added at A to restore balance. This weight measures the de- flecting force of the wind. With smooth rotor pressure was 5.15 pounds, while with corrugated rotor it was 23.2 pounds per square foot of longitudinal cross - section of cylinder. Pressure on rotor in direction of wind was found as in Fig. 4. The apparatus was suspended as a pen- dulum with rotcr at rest and in the path of wind. By means of MOTOR CYLINDER Below in Fig. 6 is shown Flettner's rotor ship. The lines weight, sufficient force was ap- and numbers on the chart below show relative pulling powers. plied to counteract wind and was BLOWER The first three are based on our experiments, while the fourth found to be 6.44 pounds per is from data made public by Flettner. The discrepancy be square foot of projected area. tween lines 1 and 4 seems to indicate that the merits of the The air turbine ship in Fig. 7 rotor ship have been greatly exaggerated, although the flanges has advantages over the rotor on Flettner's rotors are said by authorities to greatly increase ship, although the latter gives efficiency. slightly more propulsive force for same wind exposure. With G- 100 SMOOTH ROTOR turbine ship, storage batteries which drive electric motors for 462 CORRUGATED ROTOR propulsion are charged by generators. 345 AIR TURBINE.OR WINDMILL

1 241 SMOOTH ROTOR AS CLAIMED BY FLETTNER r- TURBINE BLADES

EMERGENCY SCREW DIESEL GENERATOR ENGINE 6

www.americanradiohistory.com Science and Invention for April, 1925 Super-Charger for AutomobIllica By J. H. W. KERSTON, Automotive Engineer

FUEL SUPPLY SPEEDIi. FUEL SUPPK LY \I LEA PER i CUJP, FPOANM T FUEL SUPPLY ACCE LSAT IO N TO CARBURETOR FORCED INDUCTICN PIPE

NORMAL AIR SUPPLY AIR TEMPERAUR REGULATOR

Above : A top view of the Mer- cedes super- charger showing all of the component parts.

VACUUM TANK ENGINE

INTAKE MANIFOLD GASOLINEn= FEED AIR INTAKE CARBURETOR

DISC AIR HIGH PRESSURE AIR BEING FED' CLUTCH BLOWER \ TO CARBURETOR BEVEL GEAR. I II

ACCELERATOR PEDAL

The manufacturers of the Mercedes car have installed on the engine of When the bevel gears are meshed by the accelerator pedal, this blower their machine a super- charger working on the same principle as that starts operating and at the same time a gasoline pump forces more employed in airplane engines for use in attaining high altitudes. The gasoline into the carburetor than would normally be supplied. At principle here is used so as to make it possible to fill the cylinders with lower speeds, the gasoline merely flows through the pump and is not more gasoline than is ordinarily possible and so obtain higher speeds forced. At this time. the bevel gears are not meshed. The illustration and faster acceleration. Multiple carburetors have been tried with in the upper right -hand corner shows the effect of the use of a super- charger. If at a speed of fifty miles an hour, the super- charger is put indifferent success. The super- charger illustrated above has given more into use, the speed immediately increases about 30 %. In acceleration positive and efficient results. A blower forces warm air from the ex- tests, a car using a super- charger will pick up about 30% faster than haust manifold covering, through the carburetor and into the engine. without it. EnlCc;Ilei:I AutouganbIllle Sigma

A novel type of automobile signal has caused the initial models of the sig- been designed by an American genius nals to vibrate and also because play- and is illustrated in action on the fully inclined boys could swing the right. A white arrow electrically op- arrow of these devices and thereby erated indicates the direction in cause the buzzer to operate, the im- which the car is to turn. The me- proved models have incorporated chanism of this device is shown in therein a locking system actuated by perspective and cross -section below. the same magnets that cause the ar- Because of the fact that road shocks row to swing. This is shown in detail in the lower left -hand corner. The magnets attract the armature to the dotted line position, releasing the arrow.

The circuit showing the connections of this ARROW 'SHAFT new automobile signal is given at the right. A switch conveniently located on the steer- ing column closes the circuit of one or the SPRING ZZ ER other of the magnets, depending upon the desires of the operator. A magnet is ener- gized which draws an armature down, oper- SW. ating the arrow. At the same time the spring illustrated at the left is released and a buz- N, zer starts operating, indicating the signal is CAR BATTERY working. Also, the stop light is illuminated. MAGNET COILS

www.americanradiohistory.com Science and Invention for April, 1925 1191 e rin Iron toms Vacuum Tube Amplifier Makes This Possible.

p °00000 000000 Extreme left : Apparatus for listening to the motion of atoms in iron. 000000

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IRON 'ARTICLES BEFORE BEING MAGNETIZED í,

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Above : How the atoms of a bar of iron line up when the bar is magnetized.

HIGH AMPLIFICATION VACUUM TUBE $I41 ELI" +90 voLT'B" BAT. s RECEIVERS ó Y °EEOLLH z SA-12 uv 199

hIu1h1

'-.4.5 VOLT -90 VOLT "B f BAT.

The phenomenon of magnetism is no longer a silent one. With a new in or near the coil, it becomes magnetized and a loud roar may be heard device produced in the Research Laboratories of the General Electric in the headphones, presumably as the atoms or particles constituting the Co., the change which takes place in a piece of iron when it becomes bar re- arrange their position as shown in our illustration. This theory magnetized may be made audible. This device is an outgrowth of the is supported by the fact that when the iron bar is first placed in the idea advanced by a German scientist, Dr. H. Barkhausen. In essence, pick -up coil, a loud roar is heard. H then the bar is removed and immedi- the apparatus consists of a cascade vacuum -tube amplifier, connected to a ately replaced before it loses its magnetism, only a very slight sound will coil of wire in the manner illustrated above. When a bar of iron is placed be heard as few of the particles have had time to become disarranged. D vice C tes Life oats Utilizes Sound Waves Projected Through Water.

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ROD IS RIVETED To DIAPHRAGM ON BOT1O OF CONE

Heretofore lif= boats when put out from a cisabled or s.king vessel have teen at the r_ercy of th. elements and have had no means of cnmunicating with a rescue ship. The de -ice illustrated herewith, how- ver, cesignec by the Submarine Signal - - - 1 Corporation nay be of great aid. It is ...... -, ,.,-- - ...... hown in detail in the upper right -hand in- -... -., JO, i y = N. r ` 4 vert, and is c erated by tapping the end at - ® - . ' *' . ' -egular interAls with a hammer. These .p ®,! , ,, , . i.i I + + w :ignals ° are picked up by a submarine r s.y.,,' ~ , direction finccr on board the rescue ship ' . A .i0 . '1110, ' a 4414, and by crui: ng towards the sound, that P ¡/ ' /... '40014".."- a ` `+ . ship can c.ickly locate the life boat. . o' l ' _.._...

www.americanradiohistory.com 1192 Science and Invention for zIpril, 1925 Wateir zne zc0000

The water and land tractor illustrated herewith was designed by Mr. Asher Knepper of Redfield, S D. A light low -powered gasoline engine is freely suspended from the center shaft or axle. When this engine operates, it constantly attempts to climb up the inside of the ball and consequently displaces the center of gravity of the same, causing the device to move forward. The device will run at either low or high speeds, is economical on its gasoline consumption and may be used in water or on land. 11°e:eoopc and Eye 10AM o noe Gauge

The device illustrated is used for measuring the distance between the eyes, so that optical instruments may be accurately suited to the user.

.i t.

The instrument at the right is a foreign telescope only 23/4" long, which may be folded neatly into a box about the size of a match box. Its weight is about one -fifth of a pound, and it will magnify objects at short or great distances. Its. field is at least three times larger than that of Galileian eight - power telescopes. -Dr. Albert Neuburger.

Mirrors are now used at street intersections in England to reflect images of cars approaching on side streets. PiccAecclS Hapo

Protect maps and charts and make them washable by coating with collodion spread on with a knife or use celluloid scraps dissolved in amyl- acetate. -R. B. Wailes.

www.americanradiohistory.com f nrv .irt,1 0.1 ,. l 9r,1 f'%,, Ocliditfi s in the News

The largest s a t o m o- y,le lamp ever If an automobile were as much Below is a photo of a German sub-sea armor which permits the -lade; for exh.- 'arger than the average car as this diver to work five hundred and twenty -five feet below sea level aition purposes 4111t lamp is _bigger than the ordinary for two hours at a time. These figures are from tests claimed ay the General automobile lamp, it would be as long to have been made. The diver works at atmospheric pressure, Electric Co. as seven Pullman sleepers.

The machine shown at the left takes X -ray pictures of pearls. If smooth gradations appear '- Pearl is of good quality, whereas the cultured pearl shows characteristic spots. The inventor is holding the .t camera and pearl. 11111111111F. AMP-

o THIS GRADIENT 1Ií3 IS

The Otophone above is a new invention for the deaf. The device is essentially a microphone which is connected to the input side of a two -stage vacuum tube amplifying circuit carried in a small hand grip. This grip also contains the necessary batteries. The sound being amplified is conveyed to the bony structure of the skull, and in the above photo this ;a done through the agency of the hat.

The photo at the left shows a novel monorail car which can travel at a speed of eighty miles an hour. It is planned to use this in the new tube which is to be built under the rivor Tyne in England, linking the towns of North and South Shield. The power is obtained from the wheels and the rail overhead. The gyroscope may be seen an- -lerslung in the ,enter of the ear.

www.americanradiohistory.com Science and Inv°ntion for 9pril, 1925 The LAving eath, By JOHN MARTIN LEAHY

SYNOPSIS Captain Livingstone, an Antarctic explorer, communicates with Darwin Frontenac, a famous scientist who has conducted research work in- volving methods of inducing hibernations in mammals. 7'o Darwin Frontenac and Bond Mc- Question, a reporter, the Captain recounts a weird tale of discoveries in the Antarctic, He tells how a land of palm trees and luxurious flowers was found far south of the Antarctic cir de and how during part of their exploration' trip, several of the members of the party were killed by an invisible "Thing." During farther explor- ations, a cave was discovered and in the floor, which consisted of a thick coating of ice, they Well did I know, found encased the body of o beautiful girl. The however. and that Captain formed the opinion that this girl was not from bitter experi- dead, but was in a state of suspended animation. ence. h o w fickle, Proceeding further into the rave the explorers treacherous, heart- discovered a huge stone doorway guarded by a less the Parcae real- tremendous carved figure of a harpie. They could ly are. But that un- not open the door and so retraced their pleasant thought, .steps and started back toward their ship. On of the way, the only remaining member of the party, course, I kept to with the exception of the Captain, fell into a `. myself. Well, we cretvasse and was followed by his sled carrying shook hands all on it photographic records of the trip, and de- around. "Mush!" stroying the Captain's evidence of his findings. cried Louis Louisi- The story so interested' Frontenac and Mc- ana, cracking his Question that they decide to accompany the Cap tain on a return trip. They take long whip. And we with them 102 dogs which dogs are artificially "killed" by were off ! Frontenac and placed in a refrigerator on bourn - ship. The ship leaves port well equipped, although in the mind of McQuestion, the first mate is not to be trusted. After they become encased in the ice as far south as they can go, the Cap- tain, while walking over the surface of the ice - is suddenly attacked by a killer whale that breaks through the ice and the Captain is killed. Just before establishing their depot on land, the dogs are reanimated with no disastrous ,Ef- fects. Three trips of exploration are made from the central depot and on each one facts are discovered that confirm the Captain's story. Fran - tenac, however. startles everyone with a state nient to the effect that he does not believe that "the Captain saw everything that he found."

SEVENTH INSTALLMENT gloomy mountains began to turn dark and ney- though some extraordinary mirage ef- CHAPTER XXII sinister, and ere long we ,were again in the fects were seen. Our surroundings at times midst of a tearing blizzard. assumed Find so strange and fantastic an aspect We "Her" On the succeeding morning, however, the that one fancied he was looking upon the DURING the return journey came our weather had cleared, and we were under work of some viewless cosmic magician. first experience with the dreaded way at an early hour. We were tiow some In the Antarctic things are certainly not blizzard of the Antarctic. It burst hundred and twenty miles from the hut- always what they seem. And in this, I be- upon us in the early hours of the which, by the way, was situated in latitude lieve, lies the explanation of those supposed morning, and it did not subside till near 77° 45'. Nothing worthy of note, however, discoveries there of lands and mountains midnight. It was rather snug in our tent, occurred during the remainder of that jour- that never existed where they were seep. occupied by Frontenac, Nunatak and myself, and in the other tent, too; but I found the inaction pretty trying. It is anything but pleasant to sit on (or in) one's sleeping - bag for hours at a stretch whilst storm - demons howl like spectral maniacs and pull and tug at your shelter. The only thing one can do in such circumstances is to read or write. As for writing, I brought my journal entries forward, right up to the moment. As for reading, it so chanced that there was but a single volume at hand- Ntrratit'e of 4. Gordon Pym. For two hours or so I perused its grisly pages, then tossed the little red volume over to Nunatak and wished him joy. It so chanced (1 assure you it was an accident) that the hook came down right on Nunatak's nose, but Louis Louisiana didn't mind a little thing like that. As for Frontenac, he was writing, writing. Goodness only knows what he was always writing about. As is usual. the thermometer rose during the blizzard-from minus 30° to minus 10 °. When we turned out the next morning, the weather, though the sun was not risen yet, was smiling brightly upon us. Nunatak was of the opinion. however, that her smile was Ti "kinda vampish-"- And Nunatak was right. For, in the each. .lee7'r there in her bed of cloudy crystal. the men. clustered together the :ih, before ice ant' .4it:.rnoor, the aka. the netw >e;ipc ar,d looking in upon her in wonder arid in aw.

www.americanradiohistory.com Science ard Invention for April, 1925

Amundsen gives a striking instance of the exception, and that single exception was Pro- strange effects produced by atmospheric fessor Archimedes Bukink. He was the anomalies in those regions. only one of us who was monarch of his "1 remember," he says, "our astonishment hours. He could spend them studying the on the return journey [from the Pole] on flaming of the wondrous aurora australis- finding the whole landscape completely trans- first seen on March the 25th = counting the formed! If it had not been for Mount Hel- hairs on the legs of some microscopic in- mer Hanssen, it would have been difficult for habitant of Summer Haven or doing what- us to know where we were. The atmosphere ever his heart listed. And my opinion of ill those regions may play the most awkward the worthy Bukink, as I watched him, be- tricks." gan to go up a few pegs. There were some We were learning that. busy men there at Summer Haven, but the Right glad were we when we drew up at busiest man of them all, I do verily believe, the hut-glad that the work was done and was Archimedes Bukink. gladder still that we had done so well. "l am mighty glad, Bond," Frontenac once On the 26th of April the sun left us, to said to me, "that we didn't head straight for be seen no more for four months. At mid- the Gardens." day, though, he came up very close to the "Why?" horizon, was and there then (if the sky was "Because, amongst other things, I grieve not overcast) a strong glow along the sky- to find that in several instances my judgment line in that direction, and the rays would of the men was lamentably at fault. Had light up the lofty heights of Mount Theo- we set out on our march straightway, Rustad dore Roosevelt and Mount Woodrow Wil- would have been one of the party." son. But the sun was rapidly increasing his "I have that myself." northern declination, and soon even those wondered about awesome heights were no longer touched by "The remark," said Darwin Frontenac, "is his rays at noon. Twilight now reigned a supererogatory one, but I can't help say- throughout most of the twenty -four hours; ing that Rustad has proved himself utterly for a brief interval around midnight there unworthy his place in the expedition, to say was darkness, the sun, at the noon of night. nothing of being a member of the southern He raised his being twenty-seven or twenty -eight degrees party. His true place is upon a soap -box. skeleton arm and below the sensible horizon and some degrees "Mistakes may be made," he went on, pointed. . . . farther, of course, below the apparent one. "without anything awful ensuing; we have The long, long night had come; but it made them, and undoubtedly we shall make for a very few moments. Great was our must not be imagined that we had settled more. But there must be no mistake with rejoicing, notwithstanding. down to a life of idleness and boredom. regard to the personnel of the southern The sun had returned! He was rapidly Far from it. Much was to be clone, and we party." decreasing his northern declination, at the were doing much. Frontenac had things This was the first time I had heard him rate (roughly) of a degree in every three on a routine basis. There was none of that speak so gravely, and needless to say it gave days ; that start for which we had so long pernicious system of depending upon volun- me something to think about. I had all along been waiting (whilst preparing) was not far teers- pernicious in that the willing ones do regarded in a very sober light that adven- away now. A few weeks, and we would h' more than their share, whilst the slackers ture for which we were now so impatiently heading south- south, towards Sleepint; grin up their sleeves. waiting; it was only at this moment, how- Beauty and the Gardens of Paradise. It is a regrettable fact. but none the less ever, that I began to realize how very seri- Paradise? There seemed, at any rate to is it a fact because it is regrettable, that ously it was regarded by Darwin Frontenac me, something of mockery in that name it is almost impossible to gather together a himself. which Captain Livingstone had chosen. body of men, however inconsiderable in size, The days passed, some of them swiftly Paradise? I prayed God, deep in my without finding when the test comes that you enough, some of them dragging. They be- heart, that it would not prove abhorent to us have a shirker amongst them; and fortunate came weeks, months. And then at last, on as hell's foulest corner. is that leader who finds that he has no more the 19th of August, there was the sun peep- Came at last the day -the 14th of Septem- than one. ing above the northern skyline at noon ! To ber. This was an early start, but Frontenac Suth individuals, I was sorry to discover, see this great event, we had ascended to the was anxious to get to the valley of the palm. we had with us; but Darwin Frontenac saw summit of one of the hills, whence was to trees at the earliest date possible, so as to to it that the shirkers did not shirk. Every be had a view of the distant sea -horizon, in have time for a thorough exploration of that member of the expedition had his routine this case ice -horizon, for the sea was com- strange region (unless, indeed, it should work to do. and that work was done. pletely frozen over. Only the edge of the prove of greater extent than we had reason I say every member, but there was one great glowing disk was visible, and that but (Continued on page 12401

"Look, look!" he cried. "nacre it comes! See it! What did I tell ycu ?" The creature was new visible-a human, fearsome figure. "Stand together, men," came a hollow voice, that of itansen. This is nc man! ' T i s something from hell tself !"

ir www.americanradiohistory.com ,raniP rind lnçrnlfOrt /or Ibrrl. !'/_'i

By DR. GENE PROFESSOR OF

HE recent return of Dr. Donald B. MacMillan, the well -known arctic ex- - plorer, who reports that the depth of ice in 'Greenland is increasing, brings up the question of whether or not we shall have another ice -age. Geologists tell us that five times in the history of the earth an ice -sheet has crept down from the North Pole and covered the North American Continent. The dates of Z. 0N74?/© these can only be fixed approximately, but it ------is likely that the first occurred some I,600,- 000 years ago, followed by others at intervals which were halved at each recurrence - AGARA FALLS 800.000, 400,000, 200,000 and 100,000 years. HERE It appears that the next age of glaciation should take place about ?E 25000 50,000 years after YEARS AGO the last. When the last sheet of ice that overspread ERODED TO the American continent was retreating, it HERE If the entire face of the sun left a new path for the water from the Great were to be covered with sun Lakes or Lake Erie to flow to the St. Law- spots, the heat transmitted rence. That path lay to the along what is known earth would be so as the Niagara River. Now reduced twat another ice age when this new river started flowing, it had a fall would be possible. Left : at the How the position of Niagara entrance to Lake Ontario. Since that time it has IN 2V000 YEARS Fall, has changed. been eroding back toward Lake Erie. Since it started at the time MORE IT the ice -sheet was WILL passing that point, if we calculate the aver- ERIE ERODE TO HERE age backward erosion per year and divide DRAIN it into the distance between this point _,LAKE ERIE and the present location of the falls, we will obtain the time which has elapsed since the ice -sheet was on that spot. The actual erosion Below: How the rays of took probably 25,000 years the sun passing through and to this must be added 20,000 to 30,000 glass or carbon dioxide years for the period of retreat of the ice - are retained. sheet before it reached the Niagara River and enabled it to start running. The total time, therefore, since the last age is 45,000 to 55,000 years. It appears that another ice - age may GLASS be due in a very short time, geo- SUN'S RAYS logically speaking. However, there is at TRANSMITTED the present time no need for the general pub- AND ABSORBED lic to become alarmed at this prospect. Such a phenomenon will probably not BY occur with- INTERIOR in the lifetime of the present generation or even of several generations to follow. Time expressed in geographical terms as being short usually means a thousand years or more. In the life history of this little earth : REfLECTED of ours, a mere thousand years is but as a RAYS minute in the lifetime, of a human being. The causes of the ice -ages are very ob- . scure. It has been suggested that our sun may occasionally become almost totally cov- How dust from volcanic ered with the spots which are often visible eruption would cut a off upon its surface. This would so reduce the great amount of heat amount of received from the sun. heat radiated that ice would im- FINE DUST FROM mediately form on the earth. THE ERUPT/ON Another explanation may be found in the possible change in the composition of ï.6oò:00o Yas. our -1. atmosphere. The temperature inside a green- house may he quite comfortable eveti when ICE 4 ` , it is freezing without. The glass allows the ONE '1N. . sun's heat to come in, but will not allow the 800.0 00YR5. -4 re- radiated f energy to escape. Carbon dioxide MILE and water vapor in our atmosphere 400.000YR5. act like THICK rp: `s. glass in a green- house. If, for some rea- P 11J; son or other, the quantity of this were halved, I, 200.000 YR 5. another glacial t period would occur. On the t other 1, THE PRESENT` hand, an increase of only three times the amount ICE AGE +l would produce so mild a climate S 2 3 4 that magnolias i could grow in Greenland. A diagram showing the passage of the sun's rays through glass is given at the left. The rays first pass through the glass and are Above : Chart of ice ages. Note the smooth then partially absorbed and partially re- curve which indicates that another ice age flected by the interior. may be imminent. These reflected rays Right : Intense cold are again turned back such as would be produced by the glass and a by another ice great amount of heat results. age would cover New York with a one - mile thick nlanket of ice.

www.americanradiohistory.com I '1111 i navvat mnn ?mother ,r(t- )FACH EM .4'rRO1VOMX

n -to of ai i ltr i, (-` ! V t vulva ti, lust .m3'1'í 1 ,n1 'sphere mould form I, .t slue!) the sun could not rn,iiv .,eh .rust, evert from a ;mall ,used a marked local effect in I, n lirrahrre ,.en in opposite sides of die is Ir Iroan All .1' i)Icarn,. ütere is a possibility that rIelided eruption of a large v.rlcanu nnttht ,use glaciation. l'he iii' ppostte page shows how s treme)it min. it unie eruption, which by the way is not imt ;rely impossible, could cause a blanket of i( auic dust to be thrown around the earth ut distributed it) our atmosphere. Such a 'i!auket would. of course, cut off a great ,mount m)t he.tt from the sun and conse- tuently produce the effect mentioned. \ .uggestion, often made, but with little ;oundatron, is -that the earth's axis may have .tufted its position, causing the North Pole A change of lie nearer the center of the ice- capped the gulf e two. It is inure difficult, however, to find . t r earn to- force capable of moving the pole than ii :rd Green- d would to he ice -age on other grounds explain e t ti a t in view of recently learned and deduced u ntry a icts, this suggestion may be dismissed in opical cti- Ivor of more probable reasons for ice ages. raate. hie of our illustrations herewith shows 'he effect of the ocean's currents on the dis-

i ihuticm'of ice. It will be noticed that the -,iilf Stream so alleviates the climate that the solar tee -cap tion)shaded extends only ialf as far from the pole in the direction !he warm current as it does on the other N.E.LLAND

. de. if the course of the Gulf Stream were 'fanged to flow up to the coast of America. he climate of Greenland would approximate :hat of Engktnd, while the British Isle. would be no warmer than Labrador and in 6 BILLION ,it probability the side of the polar cap TONS rearest to Greenland would recede still fur - Right: Coal te- -dirir toward the pole. Thus we can see that posits indicate ire warm currents in the sea have a great mcr trcpica +. Ik5 mate. 'Below - ffect upon the temperature of the surround - rxtent of the le land. le gt. ttention should be called to the fact that 2 BILIION onan has existed throughout this time, a.- . TONS .ome human remains have been found in de- IN. SPITZ- posits between the last glacial periods. There BERGEN some evidence that the last glaciation may 'rave been very rapid. Several specimens of nammoths, caught in the drift, were frozen, net their flesh so preserved by This natural i- !geration that it is reported on one exx.a- -iiio that it was eaten by the dogs of the- :tarty. This i; illustrated in the lower right - 'and r- iriser of this page. The explorers onnected with a northern expedition were :mrti not to keep their sledge dogs away from a in the position of the pote e -emains of the mammoth so that the ani- How shift world -aune glaciation. Old possible ):d's body could he exhumed from its natu- ,osieion .) noté marked. ii resting place and preserved in its en- :rely for future study and exhibition. The lesh of this particular mammoth was as well preserved by the action of the icy_ as if it maul been freshly killed. It is really correct to say that the pole :re still in the midst of the last ice -age for he evidence is complete that the North Pole at one rime, almost a tropical region orals and plant fossils are found in Green- rod. hinge deposits of coal, which are only ,rn)ed by uxuriant growths, have been fund in Spttsihergen, as indicated herewith ni is even frmntl in Grantland, at a trtee -oi ;th,xrt 500 miles from the pole. It ( ,sell -known fact that coal depositii ion° med by tie decay of vegetable matt', btneh in turn is covered -over by soil -mil

mn-essett. - t oat deposits indicate I,,, -ICI 'W'iat i(rn t>~

www.americanradiohistory.com Science and Invention for April, 1923

, !t Ctkv-r, fS tioir ) c 1 5 c o re' l.t 5 By CLEMENT. w EZA. E D No. 38 . The Mystery of the Radio Cipher Machine.

o "There!" cried Doctor Hackensaw, pointing triumphantly to the ma chine. "Did you ever see i anything neater or more compact? It can be switched on or off to the wireless set in an instant u and will send a message qq that my correspondent l?L4Jla3 z1:' can hear with the great est ease, but that is absolutely inaudible for any one else

keys in each row. Each key when pressed ever see anything neater or more compact: down pushes down a brush similar to the It can be switched on off S this Doctor Hackensaw:" or to the wireless brushes used on dynamos. The operator set in an instant and will send a "That's my name. I do message What can when sending a message uses ten different that my correspondent for you to -day, sir ?" can hear with the wave -lengths. The idea is to rapidly change greatest ease. but that is absolutely "My name is Julius inaudi- McMasher, the wave -length used, twenty times at each ble for anyone else!" and I am head -clerk in the Constantinople revolution of the wheel. To accomplish this, "How does it office of a large New York work ?" asked young Mc- electrical firm." the operator presses down one key in each Masher, Doctor Hackensaw glanced interested. at the handsome of the twenty rows. As the wheel revolves, "As you will see, the young man who stood before him. In spite device consists of a each brush pressed down comes in turn in wheel with a broad rim. Through suitable of a slight touch of effeminacy, the young contact fellow, with one of ten contacts connected holes in the rim there pass twenty rows of with his black mustache and dash- each with a wire. of ten keys ing looked separate each the ten each --the keys in each row bear- air, like a veritable Don Juan, wires leading from different points of the ing the numbers and the doctor mentally decided I to 10. My sending set that the transmitting coil, so as to send its own wave- is arranged to send any one young man was appropriately named. He, of ten different length. Your correspondent has a similar wave -lengths and the pressing down of the however, said nothing. and McMasher con- revolves proper tinued wheel which synchronously with key decides which wave- length will yours. If he presses down the same twenty be transmitted- The idea of the machine "I have spent ten years in Constantinople is keys that you do, his wave -length will change to rapidly change my wave -length as I am and speak Turkish like a native. But as exactly as yours does, being always in tune. sending the message, thus making it affairs over there seem to be looking pretty impos while no outsider can possibly catch the mes- sible for anyone to listen in unless he has squally at-present, I wish to take some pre- sage. a wheel just like this one and revolving caution. I especially wish to be able to com- There!" cried Doctor Hackensaw, point- synchronously with it ; and municate secretly by wireless with friends unless he has ing triumphantly to the machine. "Did you the same key pressed down in each I have in Athens and in Malta. I was told rou that you had invented a device that was not very expensive, and that could be attached The young woman became intense to any wireless set and would absolutely en- ly excited and threw back her veil in sure order to get a better view of the appa- the secrecy of any message sent." ratus. "Yes, that is true," replied the doctor. "I was also told that the device was such that it could be used with a hundred or more different correspondents and yet that each of then could only catch the messages intended for him, but was utterly powerless to read the messages sent to the other correspondents. The thing doesn't seem possible, but that is what I heard." "The thing is true, nevertheless. My in- strunient is so constructed that no one can receive the message unless you wish him to, and yet he can switch in at a moment's notice when you wish him to--at least, if he iç provided with my device. "May I see the machine ?" "I will show it to you with pleasure. Walk this way, please." So saying the doctor led the young fellow into an adjoining room devoted exclusively to wireless apparatus, and taking from a stand a small wheel, he exhibited it to his visitor. The device consists of a broad -rimmed wheel, revolving vertically On the broad rim ut the wheel are twenty rows of ten

www.americanradiohistory.com Science an Invention for April, 1925

1.1

"Ha!" cried hr "So! so! my fin young fellow! Do yon imagine you can comw into a man's house lib.. this and make love to his daughter, and then escape scot -free? Hey, guards, seirr me this dog of an unbeliever, and I'll make an example of him"

"Let us suppose, for instance, that you and speak my message into the instrument, The bination each time just before sending the I have decided on the following twenty nunm- wave -length keeps changing but as your message. You and your correspondent c.,, hers: wave -length is always the same as mine, you have a code -word for each number, so t, 9.2, 7, 3, 4, 0, ñ, 5, 8, 1, 2, 5, 8, 3, 4. 0. 7, 9.6, 1 hear every word easily, while an outsider telephoning twenty words he can change in, I press down key 9 in the first row, key 2 finds it impossible to tune in. He hears keys in a minute and the order of the way. in the second row, key 7 in the third row nothing at all but occasionaly meaningless length will be completely changed. and so on unti I have all twenty keys prop- sounds." As you see the apparatus is simplicity it erly placed. You do the same on your wheel "Why can't he try different combinations self, 1' have furnished it to several broad and we start both wheels turning together until he gets the right one ?" cast stations who wish to charge for them at the same speed. Then I start sending and Doctor Hackensaw smiled. "With twenty entertainments. Only their customers al rows- of keys and ten keys in provided with the code numbers, and hew-, each row. he would have to try no one else can listen in to their prograr. 1010 different combinations be- This may seem rather hard on the genes. fore he struck the right one. or public, but will really improve the qualm in other words 100,000.000: of the broadcasting, for the entertainers wit 000,000,000,000 different com- receive pay for their productions can affor' binations. Now to try these to give their customers first -class perform hundred quadrillion different antes. There would be the same different combinations would take as between a free show and a good theatri him more than one life- cal performance that you have to pay for." time. Besides I recom- "Doctor, it's great !" cried the young man mended changing the corn- enthusiastically. "I'll take a dozen of these instruments right away, and you can count on some big orders from nie if they work all right in practice." "They'll work all right -never fear," replied Doctor Hackensaw, confidently. CHAPTER II .. . She took off the garment, and Julius McMasher was back in Constanti- letting down one nople and was busily engaged setting up a end so Julius could of the show- grasp it, she pass- wireless set, when the door ed the other end room opened and a richly dressed, though around the hinge heavily veiled, Turkish lady, accompanied by of the trap -door an attendant, carne in, and asked to see t!,, for support. So various styles of wireless apparatus. busily were the "Here Julius !" cried the manager. pair engaged that As of lady looks like one of the big hugs. they neither r.. them noticed that the handsomest man here, I'll let you tr, the girl's father make the sale. She's certainly one of th. had appeared in 'Five Hundred.'" the doorway. . . . Julius, all bows and smiles. stepped f, ward to meet the lady, and understand;, that she wished a wireless set, he ri her all the latest models and explain (Continued on pace 1238

www.americanradiohistory.com !i I 'it'll 1 114','r117nrt tor ! : is ont Latest evices

At the left is shown an ingenious egg holder which is made entirely of wire heavily gal - vanized so that it will not rust. It has six compartments to hold one egg each, and from one to six eggs at a time can be WAXING PADS boiled. This basket will prevent smashing aeac eggs or burning the Angers. -i. B Ro:'vLk

`ie ie'i e illustrated below is an ..lectric razor. Not only does it cave, but it can be made to give massage as well. It was recently ... " "strated at the New York :lectrical Show. The floor waxer and polisher illustrated above operates as it is pushed across a floor. The waxing pads and brushes reci- procate while in operation. -J. W. Von Stein

The push pins above are used to hold pictures in Their frames. -f. W. Von Stein

The idea illustrated below is a four in one ar mener. It ,.an be made to take small, medium and large sized jar tops and can be The hot jar carrier illustrated here is made ,sed co open bottles. -J. B. Roswick. of galvanized wire and two wooden handles. -J. B. Roswick.

WINIIIMErr" i

Each side of the raincoat illustrated above holds one leg of a pair of rub - her trousers. On we days the man wearing the coat unhooks the trouser legs from the coat, steps into them, and then fastens the lega to the coat by means of suspenders.

The skillet pictured below is so constructed ,hat ,t heats uniformly over its entire sur- ace. The top plate is of aluminum, and she bottom is galvanized steel. Between he wo s a layer of chamfered copper. An instructive drawing game :s shown above. A sheet of thin paper is mounted over a movable disk, and the white spaces are flied an with crayon or pencil. Geared w h e e l s W. Von Stein. trive a fan which -J. aroduces t h e acuum tor the move sweeper. It Two pieces of s non- electrical. wire form the W von Stein. hot plate. aie tan and p o t after s n o w s -ere. - i. ß. R

www.americanradiohistory.com Science and Invention for April, 1925 1201 SaanoPaing Afffplianeo frozo Tee. By JOSEPH H. KRAUS

In order to see just what effect is caused by the crashing Several of the photographs 3erewith show the of an airplane, officers of McCook Field conducted tests remains of test planes after having crashed at Wilbur Wright Field in the presence of cameramen into a concrete wall at a speed of 100 miles per and scientists. hour.

Above: Airplane stripped of Right: A photo- wings oa incline ready for its graph taken at dash to destruction. Right: the instan- an Motor started and plane ready airplane cashed for trip. into a solid concrete wall. Splin- ters and parts flew through the air for hundreds of feet, and although the ?lane w a s completely demolished, and one hundred gallons of gasoline which wert in the tank was sprayed over the wreckage, a fire did not result-

Right: Another view of a plane at the top of the specially prepared track one hundred yards long, and inclined toward the solid concrete wall.

Crashing into a concrete wall at a speed of one htndred miles per hour, several a rplanes recently were destroyed in tests at Wilbur Wright Field. The method of conducting these tests is illustrated in the lower left hand corner of Right : Another view of a skeleton plane at the this page. First tie plane, stripped instant of impact. During one of the crashes, of its wings, was placed on a run- a piece of a four bladed propeller was hurled way which was inclined towards a nearly a thousand feet in the air. wall. Obsolete types of planes were used, and m order to start NO riRL 00. £%PLOiota the old motor quickly, boiling hot CONCR,AL ivALL water was placed in the radiator. The propeller was spun over and the motor PI1070GRAP¡iEn.S BE`iP:p CO GALLONS OF 1 B0mB PROOF St13Ei-Dt started, but the plane was held in position by a rope. After the motor was running smooth- ly and was thoroughly warmed up, one assist- .A 4PLAM1E STRIPPEO OI ant pulled a cord, opening The throttle wide, 'V.IN65 £NGIUÇ, RUNNIN while another man cut the restraining rope with an axe. The plane, at full throttle and CM a down grade, raced toward the concrete PLANE TRAVr.LING AT wall at one hundred miles per hour and was 1)O MILES PER NOUR completely destroyed, but did not catch fire.

www.americanradiohistory.com s 1202 Science and Invention for April, 1925

)Th: vootT0e LS' ki\ o rm og z ó p C'1 Mulo

MOTOR BOARD

The very latest in phonograph motors is a new instrument being - manufactured by a New York concern, which aside from being built on the same principles as the ordinary electric motor, runs at a constant speed of approximately seventy revolutions per minute. There is no gearing or belts of any kind, the shaft of the motor being directly connected to the phonograph turn -table. The motor is so wired that changes of ten volts in the supply does not affect the speed. Thoog ha Needo 3Lood.

That an extra supply of blood is needed, when the brain works, has been very gra- phically shown by some German physicians and recorded in Kosntos. The patient was placed upon the pivoted table and brought to a balance. Then while resting peacefully he was suddenly confronted with a problem and asked for the solution of it. Immedi- ately the mental energy began to be applied to the problem, the table showed a tilt indicating added weight at the head end. The only possible explanation for this change in weight is that an extra amount of blood rushes from the remainder of the body to the brain for assistance in the mental processes, thus increasing the weight.

ACó vo.`.HMimp,); OO the FutuTo

With the constant popularization and increase in aerial navigation, much thought is being given to the possibilities of advertising for the benefit of passengers of airplanes. The sketch at the left, the idea of Hubert Slouka, shows one of the many possibilities which will at once make themselves obvious. In this instance the product will be advertised- usually just its name -will be cut out of a wooded area. The contrast between the dark green wooded portions and the lighter cleared area will give ample contrast to the inscription written. -Hubert Slouka..

www.americanradiohistory.com Science and Invention for April, 192. 1203 raises Cowin Devic

AN Y times a copy is desired of some object such as a bust or piece of apparatus, which is irregular in contour and an accurate copy cannot be produced by ordinary drafting methods. The system given in the picture may be used to produce exceptionally life -like illustrations which could not be clone through the regular methods. Through its use shadow effects and background may be put in with un- failing accuracy.

The screen A, is nothing more or less than a rectangular frame crossed by a the article being copied. The paper C, upon which he is making the copy, number of threads stretched across it at given intervals. One set horizontal is lined off in squares proportional to those of the screen. By adjusting the and one vertical, and parallel ineach set. The standard B, provides a peep size of the squares on the copying paper, the picture may be enlarged or hole against which the artist places his eye and through which he observes made smaller than the original. -C. T. Stone. New Tile joint

CEMENT PACKING

In preliminary tests made by the inventor, Hail, the new type tile joint shown on this pag. withstood a pressure sufficiently high to break the the between the joints. The three pictures shown above were taken during the process of putting the hydrostatic pressure on the tile. The cement is pot,red into the joint instead of being "pointed."

Almost all the previous difficulties in making tile joints have been eliminated which the cement grips. The cement packing is poured in through a hole in the new form of tile shown above. The spigot end has toothed projections, in the top of the bell end. The joint is extremely solid. -Gustav Hail.

www.americanradiohistory.com Science and Invention for April, 1925 vices

A nasal douche utilizing a partial vacuum- produc- ing pump is illustrated at left. Medicated solutions can be used effectively.

Right: A new type of private mouthpiece for telephone. Whispers will be transmitted using this mouthpiece, Below: binding post uses regulation screws. A new type of portable electric fan has been recently placed on the market that carries its own current supply. A small electric battery fits in the handle and drives the motor. This device is illustrated above. Left: A short strip of spring steel wire is designed to be placed over the door knob and slipped through the key as shown. This prevents the removal of the key and prevents pick- ing of the lock. -Otto Halmer.

Left : A very compact yet complete first -aid kit specially designed for the use of motorists, campers and others where space is limited.

RUBBER.

: a new To determine the amount of liquid in a Above The Neatrik, A device for holding the watch can of fruit or vegetables, the device Right: illustrated above has been designed. The rubber in- securely in the watch pocket a is removed from the can and the sert in of a pair of trousers. Left: top ab- lock which disc of the device drilled with hammer An automobile circular b s is an in- holes, placed on the material. It sinks s o r is built into and f the rests on the solid material. shocks o tegral part of gear shift until it blows. lever. -N. C. McLoud. RUf38ER

Above is shown two types of convert.ble chairs. Both types can be used either as chairs. tables :r ironing boards. The photos in the center above show both chairs converted. -A. L. Foxman.

www.americanradiohistory.com ,Crience and Invention for April, 1925 1205

tu of t t. PR cmne By S. LEONARD BASTTN

Above: The night blooming cactus fully closed. See photos at right. Above: The night Above: Four more seconds Do plant roots grow down blooming cactus photo- have passed in the life of the to avoid sunlight? The mir- graphed four seconds cactus flower and now we see ror in the above photo after the illustration at it fully opened in all its glory. would tend to prove that the right. Note h o w Eight seconds from bud to such is not the case. quickly it opened. full bloom is almost a record for flowers. A FLOWERPOT GARDEN ASMALL garden that will provide much pleasure to its owner and that will take up a minimum of room may be made from a flower pot as shown in the photographs at the left. A large pot is selected and several two -inch holes are bored in the sides as shown, leaving about the same distance between the holes. They may be made with an ordinary wood bit, exercising a little care in the process so as not to break the pot or chip it badly. Now secure some good, rich, Above: A novel decora- fine soil and a few small stones. tive umbrella formed of on growing roses. The stem Place a layer of the stones of the plant was trained the bottom of the pot to insure to grow up a straight good drainage and fill the re- stick, at the top of which mainder with the soil. Then the was a wire frame in the Left: A grass mat. bulbs may be planted as shown, shape of an umbrella. some in the top of the pot and Reaching this, the plant Grass seed is sewn thickly on a strip of some of them in the holes men- spread out with the effect wa- shown. burlap and freely tioned above. For early spring tered. After the roots planting, crocuses are the best. take hold, the mat May bemoved. EflecfrIlc FIlTeefless C®okez-

electricity for heating can Above: The various uses to which a new fireless cooker employing accessory illustrated above left, top row; roasting meat and cooking three vegetables: broiling steak The automobile be used. From right to the vaporized gasoline before it enters stewing and frying. Right center: boiling. Lower left to right ; pot heats and warming potatoes; causing more complete combus- roasting and cooking three vegetables; warming vegetables; baking and cold pack canning. the cylinders, -J. W. Von Stein. tion.

www.americanradiohistory.com Science and Invention for April, 1925 odCóo zna Ends oT Thysics By T. O'CONOR SLOANE, Ph.D.

Below is shown the effect of rotating a bunch of keys also with the disk, and at the bottom of the page a gold fish globe containing some water is rotated by an electric fan. Water first takes a parabolic shape and as it acquires the speed of rotation of the fan, forms a definite band all around the equator, as we may call it, of the globe. Solid objects may be thrown in the bowl which will share in the The effect of rotating a effect. heavy ring and a stick of wood are shown here. They tend to assume a horizontal position as they whirl.

A top is made from a phonograph record with either a wooden or metal spindle. An electric fan is concealed below it, whose shaft goes through the table, level with its surface. The top spins on the shaft while the fan turns.

We show here a number of experiments in rotary and centrifugal force. Ordinar- ily in college apparatus what is known as the whirling table is used, which is quite an expensive piece of apparatus. Above everything is done either with a twisted cord or with an electric fan. A circular board of considerable weight is suspended from a double cord as shown. A few twists are given to the cord and then by drawing a pencil or fountain pen or smooth round stick down through the cord, a high velocity is given to the board. To a hook screwed into the center of the board or plug driven therein, as shown here, various objects are attached and they are made to rotate at high speed first in one direction, coming to rest, and then rotating in the other. This can be kept up indefinitely by alternately drawing the pencil up and down.

www.americanradiohistory.com Science und Invention for April, 1925 1207 afr 66 99 c7. THE MAN WHO /qDEYOPy MYSTIFIED ..,,\RATIOR Prince of Wales, Ex- President sew et 'DRNlRGERORA yoGotD le flr¢ am, Rkk Harding, Taft, Roosevelt, Pres. 1'ORERiGGRO ws w Coolidge and other celebreities WOSI Donning, Will Attempt Writes Exclusively for To Hypnotize Patient, SCIENCE AND INVENTION 10 Miles Away. by Radie I ß,....,., m,...1 /ß.1r-NE5/

HANDKERCHIEF íIATC//f5 CLOTH TOP CLOTH BACK

)), CATCH

BLOCK HAN DKE RCH I E F SPRING ROLLER OF MATCHES SPRI NG SPRING ROLLER HINGES HORN NO, 25 OF A SERIES loud filling the air A radio set is seen on the table, its speaker with music. The performer places a cloth over the set, removes it to the front of the stage and snapping the cloth the set has vanished. In reality the set vanished before away, into he ever moved away from the table. The panel drops BLOCK OF sides fold on top of it and the back and top the table, the HALF -MATCHES PHONOGRAPH combined form a roller curtain. A phonograph is concealed in the table and a wire frame in the cloth. GLUED KEY RECORD is shown by the TOGETHER SPRING CLOCK Above and to the right a full box of matches performer. He removes one of them. lights his pipe, then ARRANGEMENT closes the box, and instantly the matches disappear and a handkerchief is found in their place. The matches are glued together in block form. hold a PACK OF Below and to the left : A cigarette box which will CARDS deck of cards snugly is opened, and the cards, thoroughly shuffled, are then dropped into the box, which is closed and WELL opened again, whereupon the performer removes one card first naming suit and face. A duplicate set SHUFFLED after the other, BORROWED of cards are fixed in the cover of the box, and these drop PACK OF down upon the shuffled deck when the cover is closed. HANDKERCHIEF CARDS PIECE right hand corner : A borrowed handkerchief is forced SMALL IN ____ Lower BOX through the palm of the hand and a piece cut out of it with OF CLOTH HELD The ends are tucked back into the palm, a pair of scissors. IN PLACE BY and the handkerchief appears whole. The method is made clear in the diagram illustrating the trick. RUBBER BAND

CARDS -ORDER EXTRA OF WHICH PIECE CU P\

lk6 NO ffffS ARE MEMO - cl & _ RIZED ELASTIC CUP Y .. CARDS FACED WITH CIGARETTE BOX LABEL ELASTIC SPADES 4- UP SLEEVE 6-DIAt1ON I0 -CU,85 CARDS DROP FROM 8-HEARTS COVER WHEN BOX IS CLOSED

BORROWE D HANDKERCHIEF

www.americanradiohistory.com 1208 Science and Invention for April, 1925 More Gambler's Tric ks Exposed By MARK MELLEN The Man Who Fooled P. T. Barnum

BOWL -O -BALL GAME GIANT SWINGER Swinge or Aerial Ball Game meet the growing demand for. The Giant á cognized u one of 88To e the fastest carnival ga ear produced and is etoo well known to Be I -O -Ball game. This game `per weuire v detailed descriptiondes The outfit of o nch ated by bowfin and o 5-inch hall attached to a heavy .chain tillerwsmall onde obells eauve with en w eye for overhead. the m to strike the return board .,a hounJ t and he wooden urge:which is Complete with instructions $12..50 back eri wìt aidlargee Each`f these i Extra fin far `hove Each 14a0 hazing paid 1 o °, b,wls mil h.. ha, aueceeded m ,,.king (our balls hit the target. he object of the game to make high store le, the With every carnival there is po, h... eco Rein. e'lows)and the bigde`ranP00. Thi, .Itows the o pra or a what is known as a giant wt te of prim wnh ,.prize tort ever Balk are held they 1 mil swinger. A bowling alley ten- Player i,e hi, Prise. Th recd all time, é 1 pin stands on a platform, and cais o baluntt'I otv malil a`Ily a bowling ball is suspended by han.^ melt' a chain from the roof of the als ding el a nbL.1 ' store. If the ten -pin is directly r std 1. o, o-2 0 piok,d under the ball, it is impossible motet to hit the pin on the backward motion of the ball.

Above is a cut showing the Bowl - 0 -Ball game. The description appearing in the advertisement explains it fully. There is no "gim- mick" (cheating device) to this. The player simply tries to make a high score which, although not entirely impossible, is highly improb- able. The balls must evade the laws of gravity, centrifugal force, etc., in order to fall in such a way GAMES OF CHANCE The Add -A -Ball R o 11 as to produce a high score.. Down is different from ALTHOUGH in daily contact with hundreds and thotsands the Teeter Tauter Roll of the general public, the carnival people might v_ll be Down in that the board The Six -Ball Roll Down dif- called a separate nation. They travel from place to gives a prize to every from the Teeter Tauter in carnivals and Lre as player, a little piece of fers taking part street fairs, expositions and for Roll Down also shown on different from the people who patronize them, or upon whom candy in exchange cents. The board can this page, in that the balls they prey, as if they were a troupe of foreigners. And they ten In one thus be used in towns in must drop into holes. have a language all their own. A side -show tent is a "kic top" of holes the six is at which the law is more row lemonade is a "juice " fact, b--siness e bottom, and in the other -the stand joint -in every rigidly enforced. T h the stall is at the top. The game is not or stand either a "store" or a "joint." chance of winning a big "gimmicked." It is just im- There are probably two hundred of these carnival caravans prize is slight. possible to do it. that start out every Spring to collect tribute, and a few of them work all the year, by going South in advance of the f ros-. As every man and woman connected with them comes home with a goodly bank -roll it is evident that the number of contributors must be large. And the chances are that one or another of these grifters has levied tribute in your immediate neighborhood- possibly you have contributed. For there are few who can resist the lure of the midway with its leather -lunged barkers and spielers, flashily- dressed sirens, lf%j SIX -BALL ROLL DOWN freaks of nature, flashy prizes and inviting hot TABLE ADDA -BALL ROLL DOWN dog and popcorn stands. me erat pppm.ritr ,ere' by Add -a -Ball Game Prompts offer the e s II and ómpac' n.is "7 ","ht" The inndd e.roil a Roll Dewn is miniature r down boar' mede of bo,ddçwood, buutifullrt finislMb This is the regulation Roll Down Table. PA feet long and Ilya inches swirl, fitted 'IM1 h ed Sri with hinged bp-up tray This outfit is too well known to need any detailed description. ntdi`tg ra°d°vmb"br Ei- y be operated everywhee and news. laite 10 ge ,play. Table t, made of M1ardwóod. TEETER TAUTER ROLL DOWN h rubber D,IIa The Rewcrd finished ith Iw e" a of `par vernisM1; a

PIGS IN CLOVER t BALL TIP -UP DOLLAR PERCENTAGE WHEEL A &Shy little tip-up store Ih.t is complete in all Our Dollar Perceug, Wheel is Ir inches in diuseter. ,read m . h,r'wood pwl..,i h a goad boeme. Tins deuils. Bo, is 11 /'al4", made of hardwood, hand. 1OY vded for eq bed ,od mark bad h nails. primarily om,ly finished and studded bras spaced as .hole 00 in .pedal aombmeiona mounted o tip over bar that is rreadily fastened to The wheel s Spill anted of th,,.-pl boolors, co- fit the counter or table. This ou t is r iced with 00a d painted m bright. gs h robs knedOCYae`dewn fw iei A b000e$Et, dependable six °glas, marbles, c hyoid `wheel et mò, W. e he board The smallest nd fastest pinted li` 1 SpateSpace Wheel ad Stand A0* sand one that t grinding e on the male 1 Space zed Stand IPA* every concessionaire should have handy tin Com,Iex. hexed for shipment $10.00 1Ìm.haon leather ds earn Each Ad

www.americanradiohistory.com Science and Invention for April, 1925 nc© Wz ea aq,Co»ne,

DAILY THE EVENINGI WORLD, THURSDA1 NEWS, THURSDAY, BULLE SEPTEMBER WHAT 1$ 192a withoPe THE PRINCE Jae Duni iñger Tells pow Prince THINKS ABOUT "master took chance Prince the other with Dunninger, Col Trick lo Show Home Folks. la day. a a g of now," he said, "Tell me what t and the mind am think. thinking of the reader told . Wales What We Call "Kid- name "Johnny." him he was ap w e,ee,.M. Yam. s. The print. ,. - m eat der." Says Society Prestidig- i-. Rrnnc itator, but Knows Magic. Who 'I Icezement. Paper for People ,ce should Astounds AMERICANA d Reader "Americans Generally Are NEW YORK tewaa't Min Isl PRINCE think Long Clever," His Parting Shot to ASTOuNDSTHE of on MIND READER, Gay Party ' Dinner Party Entertainer. Du$NINçER KINÇ OP At YOJ RE 'MIN WI or Y."- 00. OF Then The Prince of be 'IliE NAME having Belmont, . Wales lent shpw- Wins at uea Ina London new tea of mare he wales learned at Ma Wamntek,r party VOH NHY: BugTIN. Dun - Arthur pue- ash[ or tteo sap. He place a on the palm or hie Mn hand Ideedt slowly -doe It ut throuth the Id be to hit CICM had.. teat, feet above Wsv aoboay esimeaaae th. teat a s 'The hits jbow u 1, ease. Odin. ww I. Htgha,,, learned ibis pretty Jos Ad I L.' t filet tropa Denuapsr tM Wales G WORLD, WEDNESDAY. SEPTEMBER lJ1rlE Mind -Rending the Prince

THEY'vE HAD A MIND QEADEQ PRAGTKPNG ON THE PRtNCE ILY Gov. Prou % * Te Br.am, 1924: trop TEN 1 V -1)A K 1G. NUTts SEpT i" EbißE¡ TUESDAY. CITY, hooter YO { cog ,aEw the P-FANE an?iy, Cries Quickly-uiokly - E9\IÏ- Dunninger ;iiid 't' IEBj TII1M to' Pub 1 Until Gives Prince of 'wild .. attics r.onroañ.N.1 -et ,oration o Wales Cigarette Trick lcials tit To Fool Home Folks. >ay ay Gtn t. U- VERY simple trick as described and illustrated at the bottom of this page was responsible for the great amount bé A of newspaper write-ups shown by the clippings on this page. The actors in the engagement were respectively His Royal Highness, the Prince of Wales and Prof. Joseph Dunninger, known by some as "Dunninger," who writes exclusively for this ta, publication. And the trick was the simple cigarette levitation effect produced as shown herein below. Of course, "Dunninger" did some scientific mind reading at which he is adept. Then he offered the Prince a cigarette. Natural'y the Prince had to pick it out of the box "even as you and I." "Dunninger," however, merely held his hand over the box and the cigarette slowly rose up to his finger tips. Now for the secret. Extending around the small of the back is a piece of elastic attached behind the right shoulder. At the other end a thin black silk thread is secured. This thread passes down to the palm of the hand and under a ring. A tiny button is secured to the far end of this thread, and this button coated with beeswax. Pressing the pellet of beeswax against the cigarette and holding the cigarette in place while the hand is lifted, it will be seen that the thread connected with the cigarette causes the elastic band to stretch. The finger is now bent downward, locking the thread beneath the ring until the crucial moment, when releasing the pressure the cigarette rises up to the hand. The button is slipped through the ring with the thumb and disappears up the coat sleeve.

ELASTIC 'tf A.ROUND -- BAC K EYELET / THRU RING

www.americanradiohistory.com 1210 Science and Invention for .4pri1, 1925 ortabRe Bed- Room. Outfit

- THE ROOM OPENED UP - CLOTHES-CLOSET WASH- CABINET BED (ACCOMODATING 4 PERSONS) NIGHT -TABLE TABLE CHAIRS

THE. FOLDING ROOM OPENED, READY TO LIVE IN. The illustration directly above shows what appears to be an old fashioned bed -room suite constructed from solid oak and complete in every detail. This suite, however, manufactured FT by an Austrian concern, is capable of being completely folded and fitted together in a very small space. ' TABLE PLATE

BED '4ABLE FEET CHAIR COMPARTMENT

WASH CHAMBER LOWER COMPARTMENT

THE CHAIR WASH CHAMBER UPPER COMPARTMENT

SIDE OF BED THE CLOTHES- CLOSET OPENED, SHOWING FURNITURE INSIDE WASH CABINET

NIGHT TABLE Above is shown how all of the furniture comprising this bed -room suite fits into the clothes closet after having been disassembled. BEDS The illustration to the left indicates the method of fastening the parts of the various pieces of furniture together. When assem- CHAIR COMPARTMENT bled, the articles are very rigid and look exactly like ordinary furniture. '--CHILDREN'S BEDS. SECT ION THROUGH THE CLOTHES -CLOSET A side section view of the clothes closet is shown above. Note how each section of each piece of furniture fits in a definite place. The CHILDRENS entire suite when so folded and packed for shipment occupies the dimensions given below. OR GUEST BED 5 FT\ 6 FT 9"

-THE BED - T PROVIDING. ROOM FOR TWO PEOPLE; OR FOR PACKED CHILDREN OR GUESTS FOR SHIPPING When guests arrive, sleeping space for two additional people may be provided by the auxiliary beds that are enclosed within the regular bed as rHE WHOLE ROOM ENCLOSED IN THESE DIMENSIONS shown above. This extra bed is only four inches smaller than the other.

www.americanradiohistory.com Science and Invention for April, 1925 1211 4.41 rydzy ChemIlatcy By RAYMOND B. WAILES

WHEN THE "FLOAT" WHO MAKES THE READS "t2OO" BEST ASPIRIN ? IS THE GRAVITY OF THE ACID REALLY 1200?

1 HOW DOES SMOKING PRESERVE MEATS? f / 3 ©1925 BY SCIENCE AND INVENTION chemical product or Various tarry products, among them being No one. Aspirin is a distinct A hydrometer reading of 1200 means .200 and is the same re- heavy creosote, are distilled from woody materials just as sugar or salt, that solution is one and two -tenths as makes it. It is not a mixture decimal point makes when burned in insufficient air and they have gardless of who as water. Eliminating the or blend that requires skill. the scale somewhat easier to read. a germicidal effect on meats. . ANHAT USEFUL METAL IS IN CLAY ? WHY DOESN'T CARBON IN INDIA i INK SETTLE OUT ?

WHAT CHEAP CHEMICAL m lllllll MAKES THE BEST '- W,mum RAT POISON 'IÑDIÄ.ÏNK 6

Iron is found in impure clay, but the char- The carbon in India drawing ink is in a Barium carbonate or powdered witherite, a acteristic metal which is there and in great "colloidal" or unfilterable form. The particles mineral, makes one of the best rat poisons. quantities is aluminum. Commercially, alumi- are so small that they are actually suspended The material is very cheap when purchased num is usually obtained from the mineral in the liquid, and therefore do not settle. at chemical supply houses and is easily used. bauxite.

,,rl AN OFFENSIVE LIQUID) CARBON WHAT MAKES THE NEW USE FOR 471:c 42Fi FEED TREES OR PINEAPPLE BISULPHIDE rl PLANTS VIA THE TRUNK, NOT "CHEMICAL" BOTTLES 0' THE SOIL ! ., , ,-.. GIVE OFF HEAT?

. - i sou. .

kCORK k JIM TREE PLANT OR off iron powder, a bit of salt Carbon disulphide is a liquid which gives Because metallic contained Instead of fertilizing the soil, certain species manganese dioxide when moistened be- a nauseating odor due to impurities in and drops of of trees can be fed through the trunk and come chemically active. The iron rusts and in the commercial product. Several plants through the leaves. hasten the this liquid poured into rat holes which are the case of pineapple gives off heat, while the salts the animals. Mixture of fertilizers and water is used. reaction. then plugged will elimir ate

WHY IS VINEGAR USED DOES THE AlR IN IN MANY HOME-MADE LEAK OUT WOULD YOU THINK TIRES CANDIES COR GET `STALE "? OF USING THESE FOR TREATING 1i HOOKWORM ?

.alsa.7-i

ICJ NITROGEN 11 12 vinegar con- Carbon tetrachloride which is used in both Because acids such as that in British engineers have found that tires filled vert cane sugar into invert sugar, which is to stand up non -inflammable cleaning fluids and fire ex- with inert nitrogen gas seem in creamy in consistency when near hardness tires. Possibly the air tinguishers is being employed with success longer than air filled disease. and aids the appearance of candy. "does" get stale or leak out. combating hook worm

www.americanradiohistory.com 1212 Science and Invention for April, 1925 Surface Termscon-CapIlliLary Atecy-acfl©n- C'ccohe5A®s

Capillary attraction. Use two pencils which Two strips of paper bent as shown at the left have been cleaned from grease and wet them will immediately come together and form a with water. If placed side by side, one will single strip if several drops of water are support the other as shown below. Water poured between their faces. Here again, sur- holds them together by its surface tension. face tension is the cause.

v^ Right : Capillary attraction will Due to surface tension, a bit cause water to rise between of camphor will propel a light glass plates in a hyperbola. toy boat as above.

Left: Float a match on water. A drop of oil placed near it will cause the match to move due to surface tension. Right: Capillary attraction causes water to rise higher in a small tube than in one of larger bore. Dip the tubes in water and then almost withdraw them.

Cohesion may be 411)3>,. likened to capillary at- A soap film will form across a ring of traction without the medium of a when is dipped into liquid wire the latter film. To demonstrate, cut an soapy water and withdrawn. The sur- inch length of solder from a stick of face tension between the water and the same, file the ends blunt and even the wire causes this formation, the force and press the ends firmly together. occurrng around the entire ring. The They will adhere to each other. wire might also be in squate formation.

Oil will spread on the surface of galena but water will not. Pulver- ized ore is separated from sand by whirling it in a container with oil and water. Upon standing, oil will rise to top carrying ore with it. -Raymond B. Wailes.

www.americanradiohistory.com 1213 Science and Invention for April, 1925 Seerafific Plr0bLem5 znd 131,mzlleo By ERNEST K. CHAPIN

(79o) SMOOTH ROUGH INTERIOR IMTEPJOR SURFACE SURFACE _0 _.. _ _. 5.

How can a prospector having no other facilities for testing, determine whether a supposed nugget is of pure gold when another nugget known to be of pure gold is BUNEAk-"".. at hand? = 8 .If11RNERS

Under the conditions illustrated above, will bath thermometers read alike? GLASS JAR

The two cans in Fig. 4 POROUS (UNGLAZED)I have same volume but EARTHEN JAR --7. BLACK¡ BLACK WHITE differ in shape. Under ONOHE conditions in illustration, ' I OH ` t ON SIDE must one can be pushed BOTH i _ BOTH !WHITE harder than the other? .; SIDES ONTHE SIDES I I 1 OTHER GAS GLASS TUBE O -WATER_

When illuminating gas is passed into the glass jar as in Fig. 5; bubbles issuing from glass tube will indicate increased pressure Prepare three cards as outside on in earthen jar. Pressure shown. Place one has been scarcely affected. side unseen. cup table, under Can you explain? Bet that under is same as upper. After several draws, which player has an advantage?

A far A bladder or sack of animal membrane partially filled with With two wheels as above, both on same axle, but fastened together, molasses and the mouth securely what force will be applied to car by 200 pounds pull on rope A? tied will soon swell up and may burst, as at B and C above, when placed in water. Why? Assume a large scale as illustrated at left in Fig. 9. A block of iron is balanced b y a brass weight. Will found that it can be it be By a scale. the magnetic field shown that calcium will will of the earth chloride in air the iron ob- in a few make gain weight ject greater i n minutes while crystals the will weight than of green vitriol one? lose. Why? brass

(Answers given on page 1250)

www.americanradiohistory.com 1214 Science and Invention for .4pri1 1925 \:?.>aùa:,o::aa ...,ti. II ppal'IJI, ,,, NI a+ió l q, ^ \ \ 0.1 \ \ \ ^e ° , r

ANkiW,Ta1:.wSC`RSxA Au\gaY\...VilaF[15AS\:At h0W\UaaetW`fi 1,1JF»\4 MeaIlrag Cactui.o ,zrompo - -

CHOLLA CACTUS

3 /d'DRESSED PINE STRIPS USED FOR FRAME

LARGE HOLE CUT IN TOP OF STAND AND s-/ WOOD PLUG INSERTED , TO WHICH ELEC- BRASS PLATE ATTACHED TO UNDER- TRIC FIXTURE 15 ATTACHED SIDE AT TOP OF FRAME, TO HOLD THE -- BARK S. "THICK SHADE ON TOP OF ELECTRIC FIXTURE -PITH CENTRE 'ó' ELECTRIC -- CACTUS WOOD !°oP FIXTURE IS 7 ", STAND COMPETE IS 21" HIGH

SHADE FRAME 6 4 STRIPS FOR TRIMMING AT TOP AT TOP, 16"SQUARE

'' 1." WOOD PLATES AT BOTTOM, 8" 4 - -D ATTACHED TO BOT- HIGH 4 STRIPS FOR CORNERS TOM OF LEGS TO WHICH FELT IS GLUED 4 STRIPS FOR BOTTOM The above photographs and drawings show how the Cholla cactus can be be exercised, so that the spines do not get into the When made into a very beautiful and skin. the bark novel lamp. In the upper left -hand corner is comes off, the wood appears to be very knotty. After all of the pith has a photo of the finished lamp, made by the been author. Parchment paper stretched removed the wood is full of holes. The top af the frame is now hollowed out across the corners of the shade frame and then painted with natural scenery, and plugged for the electric light some of which is shown fixture. The stand is stained and rubbed in the upper right -hand photograph, makes a very down. Meanwhile a frame is constructed effective and attractive lamp. First, as indicated in the diagram, and a piece of cactus is cut off as illustrated covered with parchment and painted. The edges of this frame are fitted in the top center diagram. The bark is then entirely removed with but care must cactus trimmings and the whole makes a picturesque lamp. -Byron W. Sieg. MagnetIlc D®®rr Loc5,o

MAGNETIC LOCK

SWITCH POINTS,

By fitting flashlight a with two switch points, as illustrated at the right, and one unacquainted with the secret. Pressing the switch points upon two constructing a magnetically operated lock, the experimenter will have pro- others mounted on the door, operates the solenoid and causes duced something the bolt to be rather unique; the door cannot possibly be opened by any- drawn into it, thus opening the door.-Philippe A. Judd, Reporter No. 7297.

www.americanradiohistory.com Science and Invention for April, 1925 1215

1yETqL- 7 P( PREPARIPIG

AS STOVE CLEAN BFASS PLATE WARM PLATE ASPHALTUM !J ,,...,%/i , 1 /,'' jtl''1 IIIIhiÌl ( , g,, llll(,111 : liI I l I III (í1 l II

SOME very beautiful effects, such as the one \ I illustrated in the upper lefthand corner of this . may be obtained by properly etching page, . HARD and filling copper plates. The procedure is illus- TRACE DESIGN WITH trated herewith. (1) A clean brass plate of the PENCIL AND CUT OUT FOIL desired size is warmed over a gas flame and (2) WITH SHARP KNIFE coated with asphaltum. Then, (3) a sheet of lead ASPHALTUM COVERED foil is smoothed out over the brass plate and, (4) BRA55 PLATE a design is traced on the foil and the parts to be etched are cut away with a very sharp knife. A cloth saturated with turpentine is then used to remove the asphaltum, (5). A composition is then made, (6) and a ring formed of the mixture around the part to be etched, (7). An acid solution (8) is then made up and poured into the space formed by the ring, care being taken that the LEAD FOI plate is level. The acid is left on until the copper plate is sufficiently etched. This length of time must be determined by experiment. The acid is then washed off with warm water, the foil removed and the asphaltum taken off by moistening it with turpentine and scraping. The plate is then ready SMOOTH OUT for the filling of the etched portion. ALL WRINKLES

GA5 SIMMER TOGETHER : RING I" HIGH FORMED 5TO V E 2. 03 YELLOW BEESWAX OF MIXTURE MADE AS 2 %203 PINE RESIN IN 6 AFTER COOLING

I O TALLOW V2 0 TURPENTINE AND KEEP FLAME LOW ;. /V`' ömUtt REMOVE ASPHALTUM ETCHING WITH TURPENTINE

To fill the etched plate, heat it, (10) and work sealing wax into the design. In place of sealing 1,IIIIIIII ,,,,ASN wax, a filler composed of "patent dryer" thoroughly mixed with dry color may be used. Scrape ACID OFF AND / - off the excess wax, (11) with a piece of cardboard REMOVE TINFOIL A pleasing or preferably a flexible steel knife. MOISTEN O``t` effect can be put on the plate (12) by covering FILL SPA CE ° , PLATE the plate with etching solution. after which salt ASPHALTUM, WITH MIXTUR MUST BE is applied and the surface thoroughly scrubbed. TH TURPENTINli -Joseph Crotty. OF 50%HYDROCHL I LEVEL AND CAREFULLY '' SCRAPE OFF AND .50% NITRIC ACID GA5 MILLING toSTOVE á

DIP PLATE IN ETCHING SCRAPE OFF EXCESS WAX SOLUTION REMOVE_ HEAT PLATE AND WORK WAX WITH EDGE OF CARDBOARD COVER WITH TABLE SALT 0 INTO DESIGN OR FLEXIBLE KNIFE AND SCRUB WITH BRUSH

www.americanradiohistory.com 1216 Science and Invention for April, 1925 A 5enaIlave liygromecer

CENTERLINE OF HAIR AND LEVER-4-1 TWO HOLES HERE -IF TO = BE HUNG ON WALL HAIR I,'d; PIN HAIR - = __-- A STIRRUP SPACER PIN PIN MAIN PIVOT STIRRUP t- SCREW

CARDBOARD LEVER UTS SMALL WASHER5 >r IO" BALANCE CEMENTED TO WEIGHT HOLE FOR STIRRUP LEVER 6 PAPER _ 3 SCALE -0- B' 3 IF INSTRIÿMENT IS TO HANG ON HORIZONTAL WALL- OMIT HORIZONTAL BASE BASE

ELEVATION OF HYDROMETER FEET- SECTION "A -e" A hygrometer that will indicate quite accurately the degree of moisture the hair with the indicating lever. A paper scale completes the device. contained in the air may be constructed as shown above. A human hair The fact that the hair is essentially, horizontal gives the apparatus extreme constitutes the expanding element, but it must first be boiled in water for delicacy as a minute change of length in the hair is greatly enlarged in ten minutes to increase its sensitiveness to moisture. A stirrup connects effect. -C. A. Oldroyd. Emergency' Pulleys Setscrew r Washers -Nut

Na /e for Set screw C,.BI.Center washers Set screw 8 flushing cut as shai-vn 82 When a pulley is needed in a hurry and one of the required size is not at B1 and the center washers are cut as in B2, allowing the use of a set hand, washers may be used to build up an emergency makeshift which will screw. By using fibre washers, which are procurable everywhere, a most give good results. Where a shaft is threaded at the end, the type illus- substantial pulley of any desired width may be readily built up for belts trated at A may be used. Where the pulley has to be slipped over a shaft, of any kind. -Alvin Heduall. the type illustrated at B must be employed. A bushing is necessary as in IntereatIlnt Paper Modello

When making paper or cardboard models of crystals or solid geometrical porated in lamp shades or ornaments, giving a very decorative effect. bodies, the facets may be omitted, giving a desirable transparent effect. The model shown herewith in the course of construction is of an After models of different types of crystals or designs are made, the octahedral crystal. ingenuity of the builder will show him how such designs may be incor-

The progressive drawings in this illustration show the various steps in method of assembly. This system is quite fascinating as a substitute making the model of an octahedral crystal. The heavy lines indicate the for cross -word puzzles and for one interested in crystallography will be points where cuts must be made. These should preferably be made with instructive and susceptible of considerable development.-A. Gruntal. a sharp thin bladed knife. The illustration at the top center shows the

www.americanradiohistory.com 1217 Science and Invention for April, 1925

:.r....v^..r..s.r...sc%a.....°.cr...r.^.r.a-°..r ,....r.r,,.r °.r°....r....-.,,.r.r..,r,..r...r....,r.v....r,

elere/Jf, ,..-.,.,.,....,.....,,

c.1 Free2b}lEñ.l MámKture Clewi11Fin,. Calmer ®Il WIln : EMERY WHEEL CORE OFCOIL .TOBE WOUND WEAK, AQUEOUS SOLUTION OF SULPHURIC r._ ACID

ELECTRIFIED SEALIN6WAX STRIP OF .;l METAL-, ATTRACTS DUST PARTICLES FROM INSIDE OFBELLOWS in a pail I o l The mixture to be frozen is placed The interior of a camera often accumulates BEND ON DOTTED LINE5 which in turn is placed within a large bucket fine particles of material which are as shown in the above illustration. A cold weak dust and into liable to collect on the lens. This is particu- The gearing of an ordinary emery wheel can water solution of sulphuric acid is poured true in the case of small hand -cameras be utilized to advantage in constructing a the outer container and a half cup full of larly to freeze where the bellows is opened and closed fre- coil winder. A strip of metal for supporting Glauber's salts added. It is possible quently, thereby stirring up the dust. To the core is bent and drilled as shown above, ice cream using this method. remove this material, electrify a stick of the nut holding the emery wheel to the shaft -Philippe A. Judd, Rep. No. 7297. wax by rubbing it with a piece of is loosened, and the ends of the metal strip sealing then flannel and hold it in the bellows as shown slipped under the washer. The nut is above, moving it around. tightened. -Charles Craft. -C. A. Oldroyd, Rep. 4433. urober Magnet Tray Neater Condenser TRAY OPENING TOR -COLD WATER TRAY TUBE WRAPPED WITH ABSORBENT COTTON RUBBER CRUTCH TIP SYPHON OUTLET

CAFBON LAMP

In cold weather, developing trays in photographic work become so low in temperature An easily made and quickly constructed con- When a rubber mallet is required for a cer- the developer is very slow in action. may be put hand, that denser for distillation purposes tain job and a regulation one is not at A heater made as above will remedy this. above. A bent glass tube illustrated above. together as shown a substitute may be made as A carbon filament lamp is mounted in a conducts the vapors which are cooled and A rubber crutch tip is procured and placed cigar box, in the top of which an opening in passage. The conduct- as shown. condensed their over the end of a standard hammer is cut as shown. The tray is placed over is wrapped with absorbent cotton be stretched when ing tube The rubber must usually this opening and the heat from the lamp or cloth and cold water allowed to drip p'acing the tip on a hammer and this tension heats the chemicals. -L. B. Robbins. of the water Lonk. upon it. The cooling action holds the tip in position. -Adolph condenses the vapors. -Carlyle Weiss.

Screw in Plaster P1iff7ìcl-hzocRs Spß flúil, StlflbstIltgIlte STRING TYP E WRITER

MILK BOTTLE

Emergency pinchcocks may be quickly and carriage spring of a typewriter wood screws may be made to hold easily made from clothespins and letter clips When the Ordinary a time when it is most needed, a first drilling a hole, driving a as illustrated above. Adjusting screws equip- breaks at in plaster by may be arranged as shown. The section of lead pipe therein and then turning ped with wing nuts allow exact regulation substitute pressure on the rubber tubing. weight of the milk bottle operates the car- in the screw p-epared with a wire as shown of the P. D'Ambra. above. Author please send address. -C. A. Oldroyd. Rep. No. 4433. nage as would the spring. -A.

www.americanradiohistory.com 1218 Science and Invention for flpril, 1925 ` :1\1 ..- . --_. ik , --,. 4 _c- ir:1 / '=. ./a". rssf Edited By S. GERNSBACK ' Wa.eea- Pam Copd Ti htenafs' .., ( BAND IRON POST Ve -y often electric drop lights are hung in position and it is found necessary to HOLDER change the length of the cord by EXCESS which the light is CORD hung. An oval shaped holder is cut frcm any stiff material. A dia- mond s h aped opening is then cut in the card as shown, making the corners quit e sharp. A loop is then made in the cord -WATER PAN and drawn through the An ingenious device for supplying open- chickens ing of the card. with fresh water may be made from an old bottle The cord w i l l and a pan. A stake is driven in the catch ground and two iron in the cor- bands placed so as to ners as shown. hold the bottle in the position illustrated. Two strips of celluloid are cut to the shape Fill pan -Everette A. shown above. Lugs and bottle with water. Invert the Peterson. are cut in the larger one, bottle over the pan with the mouth immersed. leaving all material attached. A reporter's Frerh water will flow into the pan when re- card is then placed in the center and covered quircd.- Herbert E. Morris, Rep. No. 9363. with the smaller strip. The flaps hold it in c©x TE'tIlC:k place and keep the card clean. Fannitñtanre poIlIlsh - R. Krieg, Rep. No. 13307. DuvIlñcel4cor

WINDOW PANE

For polishing out scratches in furniture, mix O IGINAL equal parts of the above illustrated liquids. -BLOCK OF WOOD Use only a few drops and apply with flannel. For duplicating drawings, erect a sheet of For high polish, repeat glass and place the several times and then Place drawing and blank paper finish with a dry piece of silk. a coin in a dish of water and chal- as shown. Looking through the glass lenge anyone to remove it at an -C. A. Oldroyd, Rep. No. 4433. without wetting the angle. a reflection will be seen and exact copy fingers. This can be done by inserting two of the original can quickly matches and easily be in a cork as shown above, floating drawn on the blank paper. -E. W. Kinner. IlmkIle s Pew the cork on the surface of the water and then lighting the matches. If a glass is now placed over the burning matches, and held C®IlIlapsIlbIleTubellSIlnK in position for a few seconds, it will be found that all the water in the dish will be forced up into the glass. The coin will be left dry and can easily be removed. -Dr. Albert Neuburger. Thp11vfiTo-Ag: OCß'eV rrfllff11Wfl11 s.-

WDRIVER PtECEOFPA 1II I Eg SARDINE CAN OPENER If a paste of violet aniline dye and mucilage is made up and If a piece of newspaper is folded as shown For squeezing a small bit of it placed on the above, and p'aced the material out of a collapsible nib of a pen as shown, between the edge of the tube, a sardine can writing can be done screwdriver and the slot opcner can be put to use. by merely dipping the pen in the screw, the The bottom edge of the in water. Never latter will be held to the driver tube is placed in the wipe the pen eff after use, but merely in such a way slot of the can opener and the allow that the screw may be started in latter twisted. it to dry. A pen so treated will give difficult The tube wi'l rcll up nect'y and squeeze long places where the fingers cannot hold it. out service. -J. Samachson, Rep. No. 10061. all of the material contained therein. -M. G. Sperry. -Leland B. Clark.

www.americanradiohistory.com Science and Invention for April, 1925 1219 Rezde reo FOTUM them cheaply.. This last Point is very important. INFINITE DWARFS AND GIANTS When the wireless gaine was new, and there were Editor, Science and Invention: SCIENCE AND INVENTION desires but a few wireless experimenters, the demand for There is a large question -mark on the inside of to hear from its readers. It solicits corn - amateur wireless materials and instruments was so my head in regard to the structure of matter. ments of general scientific interest, and will small that supply houses carried very incomplete to the - to charge almost prohibitive Organic and inorganic matter, according appreciate opinions ón - science subjects. The lines, and were forced electron theory, the fundamental of all matter is arguments pro and con will be aired on this prices to make any profit at all. As more and the same, one or more negative charges of elec- page. This magazine also relishes critic- more experimenters became interested in wire- tricity held in bondage by a positive charge. isms, and will present them in both palata- less, and as they became better organized, the on the sub- instruments and materials became so I have read all available literature É ble and unpalatable forms. So if you have demand for for the last year or so, and the striking to say it great that the supply houses were able to carry ject anything to say, this is the place This similarity of the atom to our solar system has in. Please limit your letters to 500 words a much more varied line and sell it cheaper. produced the question -mark mentioned, and it and address your letters to Editor -The movement went on until a great variety of equip- up such an enormous field of speculation or ment was available at very reasonable prices, and opens Readers Forum, c/o Science and Invention of imagination, that I am mired! Inasmuch as I Magazine, 53 Park Place, New York City. the study of wireless was within the reach have never seen a theoretical treatise on the almost everyone. matter in question, I am desirous of starting f "The same thing will be true of the study of same. chemistry. If a large number of experimenters The subject is too deep for the layman to do to take up the study, organize and make known their help but do that. surplus time and energy. The writer wishes more than wonder, but I can't suggest a line of work in a field which would not wants, the supply houses will begin to carry large The atom containing its nucleus and electrons lines chemical equipment and reagents at low thrilling, be thus affected in case of war, and one which of as a miniature universe, is immensely offers a splendid opportunity for patriotic service, prices, and this action in turn will encourage more and it looks to me that such being the case, the experimenters to take up the work, until a great of matter as namely, the field of chemistry. of electron is not the smallest particle "Due to German supremacy in the chemical in- organization will be built up which will be is supposed, but is probably habitat of thousands dustry, this country was, before the war, dependent immense service to the country in developing of forms of life which may be the generators or of the chemi- 'chemists to meet the ever growing need." with its upon Germany for a large proportion germs of all life. And our universe cal products needed in its industries, and when And such a movement is still in order. -EDITOR.) sun and planets is possibly only an atom of mat- of JOHN C. HENDERSON, of the German markets were closed to us, many ter, matter formed by it and the hundreds these industries were seriously affected. We must (Member American Chemical Society), other universes indicated by the Milky Way. If from Germany as well Akron, Ohio. poor little man to a secure chemical independence such is the case, it relegates as make the world "safe for democracy." - The war very unimportant position in the scheme of things of arms, in which we strove to destroy Germany's unless by evolutionary methods we continue to military supremacy, has brought about a war of SPIRITS AGAIN plane of matter as we have from the the higher brains in which we must combat her chemical Editor, SCIENCE AND INVENTION: tiny electrons. But if there is another stage or in the country by the supremacy. Every experimenter I read the letter about spiritualism in the Jan- higher continuation of matter solidfied should working knowledge of the principles MAGAZINE, form of life much get a uary issue of SCIENCE AND INVENTION universes, perchance another of general chemistry, and, if possible, of analytical and would like to comment on the same. larger than we-as we are the electron -and with and industrial chemistry, as well, in order that such things as as our span of life is I positively know that there are a life span in proportion, he may be prepared to play his part in the struggle spirit or psychic phenomena. Until recently we to that of the amoeba, for example, exists. to free the United States from its dependence medium who is a very that is of course that have had at our house a The argument against upon any foreign country for chemical products. dear friend of ours, and who has repeatedly given such a high organism would manipulate matter as a national know "The writer, therefore, suggests that séances. Things happened that absolutely could we do, but what if they do? Would we society be formed to promote the study of chemis- We only per- a germ of life in not be duplicated by any mortal. the difference any more than try, and that SCIENCE AND INVENTION sponsor the mitted members 'of our family. to be present. The the electron would know when steel was melted of the into movement and act as the official publication medium would sew his hands through the finger or powder exploded, or mercury transmuted society. SCIENCE AND INVENTION is the best fitted next to him and have would know should our earth tips to the person sitting gold? I expect we magazine in this country for such a task. Its his shoes nailed to the floor. go hurtling through space to another universe. wireless operators and various work in organizing the amateur Some of the manifestations were beautifúl lights, But probably that explains comets trumpet talk, raps and occasionally we would all other solar phenomena. would L. W. HUNT, be presented with a flower. The medium Ill. always be in a dead trance. Sometimes he would Harrisburg, the floor with force enough to cause (This some theory was the basis of a story be thrown to the injury to a person under normal circumstances. which we recently featured, entitled, "Around Having heard of spirit photography, I decided in which the earth was an "atom" and The Experimenter Universe," making more as a joke than anything else to take some all the stars and planets other "atoms," has come back! If you are one of the "spirit" pictures. I took down a picture from an ultimate structure infinitely great. Several readers of the old away. With featured the other one hundred thousand the wall of a sister who had passed stories by Clement Fezandié ELECTRICAL EXPERIMENTER, yOU will no a box camera I took a time exposure of the photo- view of the subject just mentioned, namely, the that the EXPERI- first examination atoms. The sug- doubt be glad to hear graph. and developed it. Upon possibility of life on the minute MENTER is coming back BIGGER AND I could see nothing unusual. When I took the gestion is not in itself new. -Editor.) BETTER THAN EVER. PRACTICAL picture home my folks recognized four faces on ELECTRtcS has been changed into an en- the photograph. These faces have grown plainer A Chemical Club tirely new kind of magazine entitled on the photograph every day, and are more clear first taken. I am Editor, SCIENCE AND INVENTION: .74 now than when they were to the articles by Mr. John C. Hender- inclosing the picture for your examination. Referring Experimenter a I took a son, member of the American Chemical Society, in The On another occasion after séance 1920, issue of SCIENCE AND INVENTION. In this magazine which has been greatly fresh plate and laid it under the bed. The next the August, shows a light All the articles were worthy of serious thought on enlarged in point of contents, illustra- morning I developed it. This photo the part of amateur chemical enthusiasts, and I tions and circulation, you will find the spot. advise any of them who may read this to refer following new departments: Can you offer an explanation of these things? to their old copies Of SCIENCE AND INVENTION and Experimental Radio I am a boy of sixteen and until recently did not read them. I notice that the suggestion was en- Experimental Chemistry believe in spiritualism. dorsed by the editors in a note immediately after WILL J. REHKLAU, Monroe, Mich. realize the importance of There is an entirely new treatment of the article. I did not containing experiments only. 90% (If you will take a picture of a girl whose hair the articles at that time, having become interested radio having read it of the magazine contains pure experi- is fluffed, you will find that in the picture a num- in chemistry some time later, but =_ be made out in the hair. You like to express my ideas ments written by the foremost authorities ber of faces can over recently I would respective fields, also a monthly have often observed the clouds as they go roll- . in their on the subject. As chemistry is such a great into various fantastic there must be many in- editorial by the writer. ing by, molding themselves and growing industry, section is now ,shapes, farms and figures. Sometimes the clouds terested experimenters in this line. If they were A fine roto- gravure help and added to brighten up the magazine. If will appear to be human beings; at other times banded together, would it not be a great gigantic animals. These effects are entirely natu- inspiration to those who have not had such help you want experiments, this is your maga- Sine. ral and do not take on human being -like shapes as they would receive from their fellow experi- The cloud shapes organization of this sort? The Be sure to reserve a copy from your because of any occult powers. menters in an issue is sold out. and their association in our minds with objects work of the society, encouraging the study of chem- news -dealer before the would be a THE EXPERIMENTER will be on sale familiar to ,us are due entirely to machinations of istry, as Mr. Henderson suggests, - Such at all newsstands beginning March 20th, the mind, and we believe that they appear human great help to the industry in future years. like because our mind naturally theorizes. The a society, as Mr. Henderson says, would surely 1925. chemists and same is true of the first spirit picture you took. promote the interests of the amateur Careful .scrutiny does not revealed the presence of eventually that of the whole industry. I should GeEmsbmckv in experimenter? Hugo faces. By deliberately looking for an effect think that almost every amateur Editor the photo, one could even see a hobgoblin. The chemical or otherwise, would take SCIENCE AND from this second photo showing the light area is merely INVENTION, and, therefore, any help produced in the development of the film. If you magazine, as Mr. Henderson proposes, would reach 111llll:- 1111IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIWIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII1 I should like to will take a crystal of hypo -sulphide of soda and many interested experimenters. drop it upon a plate while the saine is in the see the article published again in an effort to of the country, and in building up the greatest well process. of development, various fantastic and gro- awaken interest among the amateur chemists. amateur wireless association in the world, is resem- I. has a splendid reputation for sup- tesque shapes will be produced, some even JOHN E. CUMMINGS, JR., Wyoming, R. known, and it but we can assure you there (There are many chemical experiments being plying the latest and most authoritative wireless bling human beings, which _news to its readers. It is already is no psychic force at .stake. We will make the published in the EXPERIMENTER MAGAZINE, and electrical assertion, although we know that it you will find advertised elsewhere in this publi- publishing -a large number of chemical articles, following this work to will not please von. The medium who is sitting cation. This is an ideal publication for amateur and it would be but a step from fraud, and we desiring articles of a organization of a national society for young for you is a deliberate out -and -out experimenters. For those the are willing to prove it by offering him his railway non -technical nature we suggest such publication. chemists, a sort of Junior American Chemical him enough fare to New York City, and in addition offer For the sake of those who are not fortunate Society. of the various prizes which we have listed to have an August, 1920, issue of SCIENCE AND "The object of the society would be to encour- any of to bring all the chemi- which come under the group of manifestations INVENTION MAGAZINE on hand, we are republish- age the study chemistry, We will also Pay his expenses ing the letter of Mr. John C. Henderson. cal experimenters into one great organization, to which he produces. of experi- while here in New York City making these tests for The war -time closing of the wireless stations, enable local societies to be formed if we cannot developed field the menters who live in the same locality, and to build us, will laud him from the housetops the most popular and best for prove that he employs trickery, but will likewi'e experimenter, made it necessary for thousands of up a market for chemical supplies for amateurs, his houses will be justified in publish the exposé describing how he does scientifically inclined young Americans to find some so that the supply him in trickery. -EDITOR.) ether field of activity upon which to expend their carrying large stocks of supplies, and in selling tricks, if we catch

www.americanradiohistory.com 11220 Science and Invention for April, 1925

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'The La TEM©T vSa ezvIlsIlde The py By DR. JOSEPH M. HOWARD

ONE EXPLANATION:"... SHORT RADIO WAVES ARE IN ORDINARY LIGHT THERE P,YERACry, Nf'Tic 10O METERS OR MORE IN LENGTH ARE 50,000 WAVES PER INCH 5 li._% i . _\I/____. V./ "As-LIGHT S yJ . 4 P. i LIGHT A SHADOW SHADOW WIRELESS i 1 / T NO LIGHT HE EARr 4 INCH SPHERE N THIS ti REGION I ///

A THUS RADIO WAVES LIGHT NOW RECEIVED FOUND HERE IN THIS REGION FIG.1 ORDINARY RADIO WAVES MAY 9E LIGHT, HOWEVER, WILL NOT DETECTED AT THE ANTIPODES:` CURVE AT ALL ABOUTA SPHERE I FIG.2 r rr 'I h is a well established fact proved by science that the only difference I Heaviside claimed that the reason for the bending of the waves is due to III tetween light and radio waves is in their lengths. Light travels in as ionized layer about 100 miles above the surface of the earth which li straight lines while radio waves which ought to follow the same laws, II' acts as a reflector. Similarly, in harmonious analogy, a spherical mirror 1 JJ are bent entirely around and can be received at the antipodes. will reflect light completely. Note the diagrams. ir `It`.. JI L Jil Pr- BENT LIGHT RAN, THE LONG WAVES LESS BENT THAN THE I7f SHORT WAVES 4 /4.4'4

GREATER VELOCITY

LESS V LOC/TY

_ WATER_

IGJ 1115, ght is also bent by refraction, a well-known phenomenon which takes ,l ' r Enstein, whose remarkable work on the theory of relativity is one of the LII place when it passes from a lighter to a denser medium and vice -versa. ;I I great achievements of modern times, shows that if we replaced the air III. Sir Joseph Larmor contends that the Heaviside layer, if it exists, would ' . by some hypothetical medium, so that the velocity of light would in- f `II act to absorb the radio waves and to damp them out quickly. Ì1 crease, its path would be curved, eventually back to its origin. nl IIL ; RADIO WAVE AT BOUNDARY EITHER SENT TO THE EARTH OR OUT TO SPACE

IFLarmor shows that a layer of electrons exists about 50 miles above the 41 i Therefore, due to the lesser absorption it is seen why short waves carry -14 medium. As i' accounts for the well -known fact that Mirth and South 10. eth and produces the same effect as such hypothetical I' further. It also N1t,I with light, the shorter radio waves are bent more than the long and I transmission is better th t and West. Tbarrhe boundary line of IL thus lie nearer the earth's surface. unequal ionian zatiEas on acts as a ier. .jI II

www.americanradiohistory.com y

1221 Science and Invention for 1l pril, 1925 ew C tezrde atczbon

Below can be noted the familiar Chicago is vieing with New scene in the operating room of York in the matter of hrcadcas} American broadcasting stations. ing stations. Each of the :e cities The wave -length when once ad- has a greater number of power justed is seldom tampered with ful stations than has anj other except when the radio inspector community in the work. Oper- makes his rounds to check up. ing up with a 500 -watt tram-. Radio broadcasting has now the lat.st sta- Tlz 100 foct antenna mitter, WBCN, mast from which t reached the stage where only in the Windy City, is now e tion aerial is suspended. the best available apparatus can transmitting on 226 meters and be used, as people always pick have been heard by sorbe Coast to coast reception may has been verified. out the best station to listen to. of our readers. The studio And what constitutes the best charmingly inviting anc rails station? The excellence of the among the best in the wmtr. modulation, the strength of the Favorable reports have come to emitted signal, the regularity of the station commenting on i-s the programs, and their intrinsic excellent programe. value, are due considerations.

an inte eis By DR. C. S. STAHL

Executing an original job, a bakelite panel, and also one of glass, can very readily be converted into a remarkably beautiful and artistic piece of decorative work. The ordinary panel will take oil paints very nicely, the only preparation necessary being that of sanding the surface. In this instance, the panel of a super- heterodyne was taste- fully painted with a landscape scene with majestic peaks gracing the background. One who is adept with the brush will find this work remunerative and should have no trouble in disposing of his handicraft. A glass cabinet thus decorated is most attractive.

www.americanradiohistory.com 4

1222 Science and Invention for April, 1925 fingle onn-oR Recefiver5 PART I. By LEON L. ADELMAN, A.M., I.R.E.

A six tube receiver employing UV-199 tubes is shown here. It uses one tuning control and THERE is a decided tendency on the part a stabilizer. This latter, a potentiometer has 1. of the public at large, and this applies to nothing to do with the tuning, being used to those who have as yet not purchased a re- control the volume and clarity of the incom- ceiving set, ing to keep on waiting for the ulti- program. The circuit used is that of mate to appear on three stages of transformer coupled radio fre- the market. In other quency amplification (tuned input), detector words, they are skeptical about the present and two audio. day receiver and its potentialities. Just why this is evident in the radio field is hard to conjecture. Surely, one does not delay the purchase of an automobile simply because 1960, or so, may witness a radical improvement. That would be utter folly. And yet, it is safe to say that many people, through sheer misunderstanding, are losing the great wealth of joy and happiness and entertainment which is being broadcast daily by hundreds of stations which do so entirely without recompense. Their recompense lies in the slumber of approval cards and demand for reception stamps which they receive. Whether you are satisfied with the program depends largely upon your receiving set. Depicted above is shown the single control one-tube set. Receivers of this type have the disadvantage of limited selectivity.

-4- o 22i + 0 90 IT has been a great engineering prob- "B" BATT. lem to successfully build a multi- stage radio frequency receiver which could be controlled by a single dial. Below is shown an interior view of a recently Work along these lines has untiringly devised receiver which employs a variometer been carried forth for many years. tuning arrangement geared together mechanic- Slowly, as though it were part of the ally. One vernier dial is effective in sharp painful process of evolution, advance tuning. has truly been made to accomplish this end. And what is or are the main difficulties that lie in the way? Briefly, they are as follows. The design of a radio frequency transformer which can amplify with the same high efficiency over the entire broadcast wave- lengths; the problem of converting this into a tuned system which will regenerate the signal beautifully, that is, to build it up to maximum intensity, and still prevent oscillation in any part of the circuit; the necessity of producing a circuit which is selective and which is free from interference; and finally, but mainly, a set whose performance is dependable, are all factors which go to make up the successful radio set. To date, by the use of low -loss parts, the tuned radio frequency transformer problem has been over- come. The disposition of the various inductances and capacities have solved the disagreeable features that accompany excessive inductive and capacitative feed -hack. Selec- tivity has been attained by correct design and dependability by judi- cious application of well -known principles. If you don't own a radio set now, by all means get one as soon as possible. You will have no regrets, as it is always possible to exchange it for another one at a trifling cost. Name and address of manufacturers will be cheerfully given upon receipt of stamped envelope.

www.americanradiohistory.com 1223 Science and Invention for April, 1925 SENSITIVITY, selectivity, quality of reproduction and ease of control are prime requisites of the modern receiving set. Lacking in any of these essen- tials, it is safe to admit that a receiver should be relegated to the junk heap. A carefully constructed and well designed outfit will not cause radiation and thus interfere with others in the neighborhood. The set should be compact, of pleasing appearance and in order to fulfill its obligation as a part of the furniture, should be of the same finish. Price should not be a deterrent but rather a determining factor to be used as a guide in accordance with one's discretion - and pocketbook.

IN due deference to the manufacturer and to his product, the set which you are using, take time to learn all about it before condemning it immediately after installation. The respective battery connections and other wiring should be carefully checked over to ascertain correctness. Tubes, if not previously tested, should be questioned as to their operating ability and be subjected to a rigid test at the store where they were purchased. Antenna insulators, perfect ground connection, no broken wire connections and the possibility of a defective loud speaker should be considered before placing the blame on the set.

LOUD SPEAKER Tuned radio frequency amplification has long been known as an excellent medium for increased selectivity and GND distance -getting ability. Using SHORT ANT. LONG three such stages, the marufacturer ANT. of the receiver shown shove, has provided one master control and a vernier "refiner" for each step. As can be readily seen, a mechanical gearing arrangement simultaneously adjusts the wave -length for the entire circuit. A novel feature of the set is that it is equipped with a kilo -cycle scale which allows referring to one's wave -length chart for accurate setting of the dials.

STATISTICS show that the radio market is far from being saturated. The yearly turn -over has not reached its maximum. It is rapidly approaching that stage, however, because of the stanaardization now being effected. Towards this end, standardization, the single control receiver is being evolved. Electromagnetically shielded inductances and electrostatically shielded capacities constructed in a manner Above: Showing the interior of a single con- the absorption of is that of which eliminates trol set in which the main feature energy, with its inevitable losses, have a three gang grounded -rotor condenser. This feed -back, provision be- found a wide use in bringing the pres- allows of capacitative its high standard ing made in the circuit for preventing un- ent day receiver to desirable squealing: A vernier dial fulfills of perfection. Grounded rotor con- all that may be expected and the set works densers, having a minimum of high very nicely. Two rheostats and a filament quality insulation, and plates of metal The diagram of the receiver util- switch are incorporated on the panel which Below: wiring having a low resistivity and which a condenser operating on one shaft. is of the sloping type and presents a good izing triple essential to Note simplicity of detail. cannot warp easily, are appearance. condenser -tuned receivers. More and more, the manufacturer is beginning to realize the absolute necessity of the most thorough and rigorous tests applied in his labgratory before placing 0 his receiver on the market. He 0 has come to the realization that _r the public is willing to pay for a real worth -while instrument which will fully satisfy any reasonable demand made from it. But to obtain a reliable, good - working and beautiful radio set at a moderate price, without sac- rificing material quality, has re- solved itself into the mere problem of quantity production -a worthy compliment to American 'A'+ 'B + 'B°+ manufacturers who far excel in g - 221/2V. 90-135V _ - -- this endeavor. of stamped envelope. Name and address of manufacturers will be cheerfully given upon receipt

www.americanradiohistory.com 1224 Science and Invention for flpril, 1925 aura ! ean Bra -. dczot

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% ,,st+ Hamburg 392 oEberswaldé tThe,ÿSod+, &í.o50 % 2,93or 44 /) g04poa Muiden K8"Igswusterhausen ilversum B43Ó1RO P H0 AND 1050 \ E R M A N Y ^ 6588L Mns ter Leipzig° th Bnlssels° 0)G o r'r415au° H 6 Munch en 452r' % ` 1 Ón7__1i Et kf rt Pro ° ° aá67 (Kbély) 2 E gotn'sro u v 1 \ 1 ,150 t,s $ L / K 1, Paris °Stuttgart 1... 0\ A,Sf 2,600 437 1.,,. aon) 1.. )) únich° V1400 fa' udaPest 340 1 485 f 0-111!060 i6 I A N G AI S T R J IIU RY/ A N Á U Ci E ISWrrzERLAN .. u / Laus8anne ..\ l% n Genevà 70p .r Lyons° 1.100 s- ` JUGO- 1,500 Milan t SLAVIA Cir ""I HEARD Europe last night. Yes, the 1 music and Nice words carne in loud and 25 clearly, but I do not know exactly what the wave- length was." Similar remarks to this can be heard almost daily, and it gives us CORSICA pleasure to be able to give our readers o the Rom latest and most complete data concerning the 3,200 M!! N 1,800 location and wave -length of all the known European Broadcasting SARDINIA Stations. England alone has nineteen powerful stations trans- 0 mitting on wave -lengths ranging from 301 .tiEU to 1600 meters. It is possible that the neat - a f T E.R 00 R A N E A N future will witness a chain of ultra power- s e ful stations circling the globe and bringing the remote corners of the earth together. This does not necessarily imply that super - In England, there exists a tax on receiving apparatus. France and Germany both have very strin- gent rules regarding the broadcasting stations will replace our smaller reception of radio broadcasting. In the latter country, it is necessary to ones, but means file an application with the Police Department in order to procure a license for receiving! Some that another epoch will be countries forbid entirely the use of radio apparatus. America leads in radio broadcasting. established which will aid in extending aim - able worldly relations.

ou3tIl®n L®g Phono imph Unit NeutTaIlizey.

A novel type of neutralizing condenser has been evolved with the-view in mind of a compact and low -loss device to meet the requirements of the rapidly advancing field of radio science. Its features can be clearly understood by the above photo which shows it to be entirely different from the average. Mica insulation is used. A very handy device which constitutes a complete station recorder and chart having the stations listed alphabetically on a set of rollers, Those who wish to use their phonograph in con- has recently been placed on the market. The junction with the radio set, will find this new chart is so arranged that the dial readings can unit to be a very excellent reproducer. Simply be marked down for the corresponding station. by placing the reproducing needle on the de- Two small knobs protruding from the side, vice, excellent results in the way of tonal qual- facilitate quick adjustment. ity can be obtained. Name of manufacturer will be given on request.

www.americanradiohistory.com Science r:nd InTY'J/ti07L for ,Ipril, 1925 1225 Ila oddo ancl. Er o

Below : A matter of rela- What they use on the tive values. This curious other side to receive I hoto shows a small crystal our short -wave stations. set, a salt cellar and a very A large loop antenna in expensive lump of the sen- conjunction with a sitive mineral Hertzite. The 'steep tube super- heter- crystal set is valued at odyne is used to re- about $2.00 while the min- ceive with regularity eral is worth at least 500 the 94 meter wave of times that amount. As for KDKA and those of the salt cellar -oh, well, 104 meters from WGY. Woolworth's best is entirely reasonable! Just why t tis comb nation was chosen for the photo we do not know, but surmise that the photographer is thoroughly acquainted with Einstein's Relativity Theory.

How to convert a thermometer into an ammeter for the purpose of measuring filament current. Four or five turns of wire are wound around the base and connected in series with the "A" battery. To calibrate the instrument, mark off on the scale the reading when one, two, three and more tubes are burning. Refer all readings to a given temperature mark.

MIlCJ-Ocean )Rdi© WooTheT Bureau

Radio is forever playing new and important rôles. Lately c LAR S Er E otTlow ° it has been suggested by the U. S. Weather Bureau to \ Rt., OkT U keep a ship at an advantageous point in mid -Atlantic, from which position storm warnings, weather reports and other important dispatches can be sent out to ships everywhere on the ocean. The powerful government station NAA, located at Arlington near Washington, will gather all continental news and dispatch it directly to this ship. The ship will gather weather data from ships on the ocean and send the data to NAA. xa etunsrl5 -J-:--- ` tst>s t `.' tCEBEHG , *`E1^ WARRING. \ \ \

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www.americanradiohistory.com 1226 Science and Invention for April, 1925 FOUT Tub Est nc G tter By SIDNEY E. FINKELSTEIN, A. M., I. R. E. One Stage of Tuned R. F., Regenerative Detector and Two Stage A. F. Amplifier

The one who has completed his first single tube regenerative receiver and who wishes to add to its distance - getting ability and volume, will do well to follow the suggestions incorporated in this article. A 7 x 24 panel accommodates all the instruments without crowding and allows ample room for doing a neat wiring job which' is 'necessary for good results. Vernier dials are used with the two tuning condensers.

Note the pleasing appearance of the grained panel and the symmetrical lay-out of the apparatus. While six controls are shown, only two are required for tuning, with an optional dial for regeneration.

Simplicity is the keynote of this set. The list of parts becomes apparent ceiver. As will be seen in the photo, most of the connections go to bind- upon casual observation. Two .0005 variable condensers, .four standard ing posts, thus, repuiring a very minimum of soldered connections, as sockets, three rheostats, one variocoupler and spider -web coil, three fixed soldering goes to make the assembling of a radio set a disagreeable job. condensers, one grid leak, two audio frequency transformers, two jacks, Material of recognized quality is used in its construction. This has much one filament switch and the necessary binding posts, complete this re- to do with the production of really satisfactory sets.

SPIDERWEB COIL 44 TURNS N2 24 DSC T Na 24 D.SC ON ROTOR 2* DIA. 4 TOI RATIO T /64 A.F.

.0005 16 T. N°- 2 2 D S. C I.S 60025 1

WVW 2 MEG 001 0005

45 T. N2 24 D5C 16 T ON 3" DIA. TUBE D 5.0 20 20 OHM OHM 6 -OHM

XSW .006 -7 t -l- ó 6V 22p 90 42V

The first step to take is to lay out the panel and mount all the instruments. The filament 13 SPOKES q DIA circuit is then wired completely ; this is clearly depicted in the diagram. Consistent good 12 LONG work in wiring the rest of the circuit, keeping in mind the importance of making the connections as short as possible yet spacing them apart so as not to introduce undesirable losses, will, when one's work is completed, give the results to be desired. If wanted, although, DETAIL OF SPIDERWEB COIL it is not necessary, a double circuit jack can be placed in the detector circuit.

www.americanradiohistory.com Science and Invention for April, 1925 1227 he Iltz up By CHARLES CAESAR RITZ UV -199 Portable Receiver Without a Peer

Our readers will remember the ex- ceptiona ly good article on the "Ritz Super -Neu- trodyne" published in cur columns a few months ago. During this time Mr. Ritz has been laboriously at work and has perfected a receiver which a series of tests have proved it to be, without a doubt, the best set of home -made construction we have ever as yet seen. - Ed.

The cabinet containing the set is 38 inches long by 28 inches high and is 8 inches deep. Of course. it is not portable in This receiver, the result of patient research, the sense of the word to the extent that it can be carried has as its outstand:ng features : maximum around by hand, but is for automobile use in travel. sensitivity. maximum selectivity, minimum size without reduced efficiency, minimum number of controls, maximum stability during operation and most important of all employs a circuit which is easy to wire and when once built does not necessitate considerable adjustment, matching of tubes, nor gives undesirable and exasperating trouble. Deviation from given dimensions is allowable, although it is imperative that the specified parts be used. The receiver is perfectly balanced in all circuits and even a slight change in the value of such a small thing as a fixed condenser will be quite noticeable in the results attained. A panel 36 by 8 accommodates the receiver proper. Note clean -cut workmanship and self- contained batteries and the loud speaker. Especial note should be taken of the wiring which is brought out on the base sub -panel and very carefully soldered. The intermediate frequency transformers are racked together upside down, so that the leads to them become short. Four spare tubes are carried in the space near the loud speaker horn and are available in case of emergency. Six dry cells are connected in series -parallel, giving the proper filament voltage to operate the eight UV-199s. OIL 7

OSCI LLATOR COUPLER- VOLTMETER - 0-100 V. - INTERMEDIATE FREQUENCY PHONES S- STATOR , 70 TURNS OF N2.26 D.C.C. WIRE, 2 SECTIONS TRANSFORMERS JACK, ® 9Ó. /q APART- 35T. EACH -- WOUND ON 24' DIA.TUBE. SECTION // \ 1MF, R- ROTOR, 20 TURNS OF N2.26 D.C.C. WIRE / RADIO FREQ.TRANSF. ON I;i DIA.TUBE. R , 0 45V. ¡ .00025 MF. A.F.T. A.F.T. 4.0U ij .--- .004 P - - a 0 MF. I VW' O=B. s Sf /000 0006`- P. P. P. a E 4i2V. óo J .0005 MF 4r. ao- .0005 MF. VAR. z VAR. COND 006 2 M EG LOUD COND. MF -.0005 MF. gM SPEAKER Fr -_ JACK F- to "C' GATT áW N2.1 zz 4'/2 V. .0025 MF. COND. SW. CA _'I4 } DET. BATT. N2.2 OSCILLATOR 4'r2 V. LIP VOLTMETER 025 MF. C' BATT. N4.3 0 -5 V. RHEO. 25 OHMS RHEO. r'IS MME 11/2 V. 6 OHMS

For best results, it was found that a loop having a center tap and corn- frequency stages and as will be seen in the diagram, their output is tuned. posed of.15 turns 2 / feet square works remarkably well, Pacific Coast This is very important and far superior to tuning the input. (This article stations being heard every night during the week regardless of the weather has been obtained exclusively by SCIENCE AND INVENTION and is conditions. 45,000 cycle transformers give best results in the intermediate recommended to the attention and appreciation of our readers. -Ed.)

www.americanradiohistory.com 1228 Science and_1nv.ention for April, 1925

v an °?e avenhea ° rr By SIDNEY E. FINKELSTEIN, A. M., I. R. E.

An excellent addition not usually found in the average experimenter's laboratory is an accurately calibrated wave - meter. This article is perhaps the first Î' of its kind dealing with a combination 1Î// employing a single inductance and a multi- section condenser for a wave - meter covering a range between 75 and A and 600 meters. i .00075

f 1 I 0005

THE problem of having a wavemeter which / would respond accurately over a range covering from 500,000 to 4,000,000 cycles has always Ti been met with the use of at least two inductive pick -up coils together with a single condenser. Departing from such precedent, this meter was evolved with the view in mind of having a single 11110 38TURN5 ON NEON inductance in combination with a variable capa- BAKELI .000125 4110 TE TUBE INDICATING 1 city of such a value that the resultant device Vio 3" DIA LAMP would efficiently cover this large range. The 1 Î;h photo above shows the author measuring the frequency of an oscillator with the neon tube glow- The above diagram shows the different The wavemeter circuit with a neon ing brilliantly. As seen in the photo to the right, capacity values which can be obtained by indicating lamp which glows when connecting quick changes can be made in the capacity of resonance occurs. together the four sections of the condenser by simply changing the clip leads. the multiple condenser. Graphs are made covering the more important values of the condenser. In all, eight different values can be obtained from the four -section condenser, but it is inadvisable to use a capacity lower than .000125 mf. The instrument is mounted on a This is because of the pre- panel 10 by 7. The inductance con- dominant value of the induc- sists of 38 turns of No. 22 D.C.C. wire wound on a Bakelite Tube 3 tance which when connected inches in diameter. It is mounted to so small a capacity affords on the panel using two one -inch practically no change in dowel pins to keep it spaced there- wave -length. In order to from. The neon tube is of the ordi- obtain a very accurate check nary automobile variety which is on the frequency, the meter used in testing the ignition. The should be calibrated along- dial is provided with a vernier which side a standard. allows a very fine adjustment. To check up the wave- length of a trans- The wavemeter will act mitting station, it is necessary that very nicely as an absorption the pick -up coil be in close prox- circuit for use as a wave imity to the oscillator inductance. trap. The pick -up coil is It should then be taken slowly out placed in close inductive re- of the field until the lamp glows lation to the antenna circuit very faintly. This indicates reson- inductance and the condenser ance. is adjusted until the interfering station is eliminated.

700 500 240

600 200 400 Z-3 500 160 z o- w L7 Z.3 300 400 Z Z w .00012 5 LLI 120 .001 .0005 Q I 300 W 200 W 3 80 200 Q a loo loo 40 SCALE READING SCALE READING SCALE READING 0 20 40 60 80 100 0 20 40 60 80 100 0 20 40 60 80 100 The above graph represents the inductance in When using a capacity of .0005 with the in- The transmitting amateur will be very much combination with the total capacity of the ductance, the wave-length range is from 190 interested in the above graph since it effi- condenser, .001 mf., covering a range from to 425 meters. Above this value, the com- ciently covers a very important range on the 260 to 610 meters wave -length. bination does not give an accurate reading. shorter waves of 70 to 215 meters.

www.americanradiohistory.com Science and Invention for April, 1925 1229

TO Tiz the Noviic PART III

The three e:ernent vacuum tube in its simplest hook -up is shown on the right. Analyzing the circuit, the antenna a wire abcut 100 feet long and suspended AERIAL from insulators at least 25 feet from the the radio frequency VARIABLE ground, collects LEAK waves radiated through space from the \ GRID 1 -5 MEG. transmitting station. The ground con- RHEOSTAT nection completes the circuit. Tuning UV -201 A, 6 OHMS C-301 A is accomplished by means of the vari- LEAD IN able condenser placed across the induc- PHONES tion coil which, in the last analysis, is merely a concentrated form of antenna. In other words, it would be feasible, if the mechanical arrangement would allow, to use a single wire which could be reeled in and out to correspond with the wave -length range desired to be 0005 Mr received. Such a wire would have to VARIABLE N\ ' IÍ be several times longer than the aver- CONDENSER 8" BATTERY age now being emp'oyed, approximately 221 ¿TO45V. 1,000 feet long for a 450 meter wave. three different GROUND It will be noted that CLAMP methods of tuning are used, and that 0 a GROUND N the three different typ -s of tubes are incorporated in the circuits. If de- .001 MF. FIXED sired, the tuses can be interchanged, 60 T. OF WIRE ON CONDENSER filament cir- 31/2' DIA. TUBE remembering to alter the 'A' BATTERY 6V. ' cuit accordingly.

In the diagram at the left can be seen a series fixed condenser in the aerial circuit. This is to cut down the wave- AERIAL length which is caused by using too long an aerial Its interposition does not affect distant reception or signal strength. In fact, it is best to use a PHONES long aerial which collects more energy F F 00025 MF. and to place a series condenser either GRID COND.1 WD-II OR WD-I2 of the fixed or variable type in the TUBE antenna or ground leads. However, this cannot always be consumated be- .00025 ME. cause if situated in a location where FIXED there are a number of stations, interfer- CONDENSER ence is bound to result. By interference is meant the reception of several or more stations at one time without "B" BATTERY being able to tune them out at will. 221/2 VOLTS It is surprising to note what added advantage the use of a variable grid leak brings when attempting to tune in distant stations. After years of experi- VARIOMETER research, the present day tube "A" BATTERY + ment and / c e been a 11/2 V. has brought to the point where \ variable grid condenser is not a prime FI LAMENT RHEOSTAT .002 MF. FIXED necessity. Sometimes, it is advisable GROUND 20 OHMS CONDENSER to place a by -pass condenser across the phones and "B" battery, as an in- ~ -WATER PIPE f crease in signal strength will occur.

The rectifying properties of the three element tube are well known, so it will not be necessary to enumerate them here. Stress is placed, however, on the AERIAL fact that unless the grid return, as it is known, is connected to the positive side of the "A" battery, the full efficiency 1 .00025 MF VARIABLE of the tube as a detector is not realized. GRID COND. GRID LEAK F What are known as the characteristics 1.5 MEG. / UV-199 of the vacuum tube are directly re- TUBE sponsible for this condition. Briefly, ,I VARIOMETER the tube is operated at the bend or "knee" of the curve at which place the best rectifying action takes place. In this connection, the "B" battery volt- + -_ age must be taken into consideration SINGLE and varied until the incoming signal CIRCUIT becomes as loud as possible without JACK producing distortion. The circuits 60 T. OF WIRE shown on this page are of the non- ON 31/2" DIA regenerative type. They will cause no TUBE. howling or squealing. The volume ob- TAPPED EVERY tainable from them is not as loud as 10 TURNS can be rea'ized from the use of a regenerative set. In the next issue will aia FILAMENT .13" BATTERY be shown how to add regeneration to DRY DiV DRY RHEOSTAT 221/7-45 V. these receivers. It is advisable to mem- GROUND CELL CELL 'DELL 20 OHMS orize the parts of these simple circuits so as to differentiate between antenna, secondary-or grid -plate -and filament- circuits.

www.americanradiohistory.com 1.230 Science and Invention for April, 1925

In this Department we publish questions and answers which we feel are of interest to the novice and amateur. Letters addressed to this Department cannot be answered free. A charge of 25c. is made for all questions where a personal answer is desired.

NEUTRALIZING CONDENSER SOT. OF Ng. 22 30 T.OF N4.24 D.S.C. WIRE WIRE OUTPUT PUSH-PULL. 40 TURNS OF --ED - 20 DOUBLE / D.S.C. Ns. 22 O.S.C.WIRE TURNS OF N4.24 / --- INPUT PUSH -PULL TURNS U.S.C. WIRE / 60 OF -, GRID LEAK TRANSFORMER N2. 22 D. S.C. WIRE / 7 2 MEG; G

RHEO. +B TAP EVERY P 20 OHMS 10 -TURNS -' RHEO. .00025 MF. 6 OHMS 'ffniN LOUD RHEO SW. 20 OHMS SPEAKER JACK

0005 MF. VARIABLE CON D. "C" BATT. .000 P.^F-' .0005 MF VARIABLE 3 V. CONDENSER PHONES TO JACK - BATT GROUND 3 V 4TO1 RATIO AUDIO FREQUENCY TRANSE. - 'A' + - +45V. +90V. +120 V. BATT. B' BATTERY - - --' NEUTRALIZING GOND. SPIDERWEB INPUT PUSH - 20 DOUBLE T COILS 11L 30T.*24 D.S.0 PULL TRANSF. * 24 D.S.C. 1 OUTPUT' 40T. *24DSC PHONES PUSH 00025 MF. -PULL JACK TRANSF. 60T. 7A P EVERY IOT.y 02 2 MEG. D.5.C. 1.0005 MF. 20 OHMS 1 .0005 MF. 20 3 SPIDERWEB OHMS COILS L.S.' JACK A.F.T. 4-1--a d F -.006 ME 'B ® ® +45 +90 +120

(338) The addition of a push -pull amplifier to the All Circuit Set as described in the November, 1924, issue will greatly enhance its reproduc- tive qualities. This circuit is an entirely new one which is rapidly meeting with favor by all who have constructed it. ALL CIRCUIT SET brass hinge fastened to one of the spokes tallic magnesium is affixed to the plate of (338) Albertus King, Syracuse, Neb., allows a variable support. A carp and spring the tube. The plate is then heated using high asks: arrangement affords the controlling mechan- frequency induction currents. Volatilization Q. 1. "Being very much interested in the ism which varies the coupling between coils. of the magnesium takes place, the metallic set described by Miss L. Port in the Novem- The neutralizing coil should be fixed in rela- vapor absorbing the remaining gases, and ber issue, I built it and have received some tion to the secondary coil, while the tickler upon cooling, condensing on the surface of very wonderful results. Will you kindly feed -back coil in the detector circuit should the tube. The condensation does not obey publish the diagram of the circuit to which be variable in coupling to it. any fixed law as to where most of the de- is added a push -pull amplifier ?" It is best to use UV -201A or C -301A posit will occur, hence its irregularity. A. 1. We are pleased to note that you tubes with this circuit, dry cell tubes giving are also getting good results from your inferior results. A panel 7 by 21 inches CRYSTAL DETECTOR "All Circuit Set." We have received a large will accommodate the parts very nicely. (340) Alfred O'Hara, Spokane, Wash., number of replies from those who have con- wishes to know : structed the receiver, praising its good quali- TUBES Q. 1. The exact theory concerning the ties. The above diagram is, therefore, pub- rectification property of crystal detectors. lished with the idea in mind to give those (339) Martin Solitar, Oshkosh, Wis., A. 1. Although the true action of crystal who are somewhat hazy as to its exact con- wishes to find out : detectors is a complicated matter, for prac- struction a more concise explanation of the Q. 1. Whether the "silver" coating on tical purposes, it is sufficient to regard them various details. The addition of the push - the inside of a tube affects its operation or as unilateral conductors. This is for the pull amplifier does not in any way alter the is a means of determining its value. reason that they have a greater resistance to rest of the circuit. The arrangement con- A. 1. So many people are under the im- current flowing through them in one direc- sists of a tuned neutralized stage of radio pression that an unsolved mystery lies in tion than to current flowing in the other. frequency amplification, regenerative detec- the use of the silvered coating used on the Thus, for instance, when an alternating elec- tor, reflexed stage of audio frequency and inside of a tube, that they are prone to be- tromotive force is impressed on a crystal finally the push -pull amplifier which affords lieve if the coating is not completely de- detector, more current flows in one direc- excellent clarity and sufficient volume. posited there is something wrong with it. tion than in the opposite, and if a direct Spider -web coils are used throughout This is far from being the case, the so- called current meter be inserted in the circuit, it merely because they do not take up as much silver deposit being a film of condensed mag- will operate. room as the solenoid type of inductance and nesium. The resistance of ordinary crystal detec- because their field is more concentrated. In the process of evacuation, which is in tors is in the order of 1,000 to 10,000 ohms Preferably, fibre or bakelite forms about itself a very difficult task in view of the when current is passing in their "low - 3% to 4 inches in diameter and having 17 fact that even the best air pumps cannot resistance" direction. The resistance in the segments each, should be used. A small remove sufficient gas, a small piece of me- opposite direction is about 10 times as great.

r...... 1111..1111111 ...... WANTED!!! RADIO ARTICLES E WE want descriptions of new radio ideas which you have desirous of obtaining new hook -ups and descriptions of single worked out in practice. Take photographs of the im- tube sets, reflex and other types which have proven satisfac- portant parts and make pencil or pen and ink sketches of the tory. We like articles on new single tube receptors. We will hook-ups or mechanical details, et cetera. We are particularly pay good prices for your ideas. -Editor...... ,,,,,,,,,,,,, ,,,,,,,, ,.,,.,.,.,,,,., ,,, ,,, ,,,,,,,,,,,,, ,:,,,,,.,,,,111e,,,1,1,,,,,,,,,,,,1,,,,,,,,,.,,..,,,,,1,,,1,,,,.,,,,,,i,,,ii,.,.,,,,,,,..,.,,,, ..,.,,.,w,ll,,..11,,,,.11ll tawww,,,.,,,,mmn,,,,,,,,,,,,,,,,,,.,.,,.

www.americanradiohistory.com Science and Invention for April, 1925 1231

.0005 MF. VARIABLE 50 TURNS OF 10 TURNS OF CONDENSER N2. 22 D.S.C. WIRE N2. 22 D.S.C. WIRE OUTPUT +OO 500 CYCLE .0005 MF BUZZER 500 CYCLE VARIABLE BATTERY OUTPUT BATTERY BUZZER CON D. 4V2 VOLTS 4'/2 V. 20T. _p-- 0 Olfn 00001P -00000' Ilk 3" DIA. TUBE -? "LG YII i 20 TURNS OF SWITCH _ 50 TURNS 2 10 TURNS SWITCH N4.22 D. S.C. 201 -A- o+ 201 -A TUBE-`'- - SWITCH -1 v °B" BATTERY T"B" BATT. 45 VOLTS 1 MF. SWITCH 01 45V. COND. +0 O- "A' BATTERY BATTERY 1 M F. 6 VOLTS - RHEOSTAT COND. 20 OHMS VOLTMETER RHEOSTAT VOLTMETER 0-6 V. 20 OHMS 0 -6 VOLTS

11 (341) A laboratory is not complete without a calibrated oscillator. Full constructional details are given so that the experimenter can readily build one for himself. The list of material is evident from the picture diagram, a shielded box being used to contain it.

LABORATORY OSCILLATOR cedure is carried on by tuning the set to Several days elapsed in which confirmation resonance and adjusting it to eliminate all of the signals was made and, thoroughly Bertman, Bronx, N. Y., de- (341) Harry squealing. The outfit is known sometimes as satisfied that trans -oceanic transmission and sires: a driver circuit. reception was possible, Marconi gave a state- Q. 1. Information on the construction of ment to the press that messages could be a laboratory type oscillator, in which the sent through space without the use of wires radio frequency oscillations are modulated or cables, but also included the rather dis- by a 500 -cycle buzzer. PROGRESS OF RADIO couraging remark that this mode of convey- A. 1. For the numerous purposes to which ing intelligence would have little practical an oscillator of the type depicted in the (342) William J. Fink, Washington, value. above diagram can be put, we are sure that D. C., asks: At that time, 24 years ago, but one antenna many of our readers will appreciate the con- Q. 1. Will you kindly give me informa- was to be found in this country with which structional data so as to build one for them- tion regarding the date upon which radio to pick up the powerful Poldhu station's selves. was first used practically as a recognized signal. And now another series of tests To contain the apparatus, a box 16 inches means of communication? were recently carried out with English square and 6 inches deep, lined throughout A. 1. December 12th, 1901, witnessed broadcasting stations in which many hun- with sheet copper or tinfoil, will suffice. Marconi's first attempt at trans -Atlantic dreds of American radio fans plainly heard Even the bakelitc panel must be thoroughly radio communication. Listening in near St. programs broadcast from the British Isles. shielded, provision being made to carefully Johns, N. F., he was able to pick up the now There are now thousands of homes through- insulate the wiring against short circuit. The famous letter "S" broadcast from the 50- out the United States with antennae on their two meters can be mounted flush with the kilowatt spark station at Poldhu, located roofs through whose use, joy and pleasure panel or left out entirely. on the southwest tip of England. are received. Marconi worked under much The first step after the completion of the It may be, perhaps, interesting to relate greater difficulties than we with our multi - device is to calibrate it. This should be done some of the experiences which Marconi en- tube super- sensitive receivers and depended very carefully with a standard wavemeter, countered when he arrived for the prelim- upon the erratic action of the old- fashioned using the well -known click method. It will inary tests. coherer ; the average broadcast listener of today using simple re- be seen that the wave -length range is from December 10 of same four a crystal detector On the year, ceiving set is incomparably ahead of the 200 to 600 meters, using the constants given. his arrival with two assistants, a days after days 1901. Indeed, in comparison A separate battery is required to operate the wireless receiving station was set up and a coherer of buzzer. kite and silk with Marconi's first experiments the simplest hexagonal made of bamboo sets of today are almost miraculous. The oscillator can, after a fashion, be was sent aloft over the Grand Banks to used as a small transmitter, the amateur hold the antenna wire high in the air. Due Whereas the commercial trans -Atlantic always remembering to keep the wave -length to a strong wind which prevailed at the stations of today use as high as 250 kilo- below 200 meters. Of course, it is readily time, the wire snapped and the kite was lost watts of energy, the famous letter "S" was observed that the transmitted signal is of the out at sea. Undismayed, Marconi next tried successfully transmitted with but one -fifth I. C W. type, a key being submitted for the a 14-foot hydrogen balloon, but again the this power. switch in the buzzer circuit. wire broke and tangled up on the ground The last figures from official sources show The real value of the oscillator lies in its as the balloon disappeared in a fog. that there are at present approximately 600 adaptability as a means of aiding in the Undaunted, on the morning of the memor- radio broadcasting stations in this country neutralizing and calibration of receiving sets. able December 12, another kite was suc- alone. Of this number, there are less than This is readily accomplished by coupling the cessfully raised to an elevation of 400 feet a dozen using 1,000 watts of power, about exploring coil to the input transformer - and at noon the English station, more than 100 using between 500 and 1,000 watts, while antenna circuit -and, having adjusted the 2,000 miles away, was distinctly heard send- the remainder are composed of stations using oscillator for a certain wave -length, pro- ing the letter "S ". as low as a single 5- watter.

i unrnnnnm,m,nr,nnnnnn:ummm:r.::..,,.: n,mmnnunrn:n,nuuurmn:n:u iunr:rnnuununm mi,mmn:unummrnnunnnni E3 DeForest and Fessenden -Read Their Biographies °3 In the October issue of Radio News a biography of Dr. Lee AND INVENTION readers will read this important work by the DeForest, inventor of the Audion, was begun. This biography famous inventor. Prof. Reginald A. Fessenden's biography will run for 12 months in Radio News and we hope all SCIENCE began in the January number. ARTICLES APPEARING IN THE APRIL ISSUE OF "RADIO NEWS" Underground Radio. The Latest in Tuned Radio Frequency. The Eclipse and Radio Reception. By Arthur Reed. By G. C. B. Rowe. By S. R. Winters. The Grid as Traffic Regulator. About Radio Losses. By Sir Oliver Lodge. By Wilfred Taylor. A Year's Work Below Forty Meters. Building Compact Super- Heterodynes. EE The Effect of the Atmosphere on Radio Waves. By Prof. J. M. Guinchant. By John L. Reinartz. By D. J. Hall. = = n nnnnnnnrw- _e ñiuunnnununuuunnnnnnrnnnnnununnnunnnnnnnnnunnnm :: uu mmnmm11nnmm11nnnnmummmm11nuumnumununnnmunnumnnnnnmmmnnuunnunuunummmunnnnnnuummn nmr nnununu:un:nmmnnnuuuumnnnuunminunuumunnnnnmmnnr. = ...... "nn:n11:"::::::::::::rn:1:nnnn:n:munnwuuunuun:uwnnnnunnnmwunnn,. uuuwuunnuunnnunwmunnnnnnn _

www.americanradiohistory.com 1232 Science and Invention for April, 1925

'J Y!! '. Ll./ y y ` V.S. ' ' ' ' ' '' / -L ' ' '' '' ''LL 'L 'YS/. Y L'L L LLYY 'YY i'. . YY L °'. / ' ' ' PATENT ' ' ' ' ' OFFICE WñndshieIld CIleaneT Automatic Tec©p

.v.O`\ As\\\VuN__`wA D I R E C T I ON O F TRAVEL COIN SLOT

FRONT WINDSHIELD hÌ til AIR INTAKE

UNI VERSAI JOINT ,,i- tif f SE F1 VENUS A., I ' // No. 1,517,365, issued to W. Kleine deals with a novel type of wind- No. 1,517,731, issued to C. R. Johnson, covers a novel type of tele- shield cleaner which uses no mechanical or electrical means for keep- scope through which a person may view various distant objects by ing the windshield of an automobile clear of rain and snow. Two air merely inserting a coin in a slot and pressing a button. The coin intakes such as illustrated in the insert above are mounted, one on releases the button which, when pressure is applied, forces to one side either side of the windshield. The draught of air thus forced across a slide which normally obscures the view through the telescope, enabling the glass prevents the accumulation of snow or moisture thereon. the patron to look through the instrument. A suitable pivoted base is provided. Cigarette ©r WANTED CabRe 5uppos-4 ARTICLES pertaining to automobiles such as handy kinks, roadside repairs and anything of interest to the man who drives a car. $50.00 in prizes every month are offered by MOTOR CAMPER AND TOURIST for such articles. Get a copy at your newsstand and see what is wanted. If your newsdealer cannot supply you send for free sample copy to: MOTOR CAMPER & TOURIST 53 Park Place, New York City.

No. 1,517,934, issued to C. E. Anderson, protects a novel type of cigarette holder de- No. 1,516,781, issued to O. F. Nylen, designed for use by those who do not desire to CeIlfl Tester scribes a movable clamp for holding the cable have their fingers stained by the tar of cig- connecting electrical instruments in such a arettes. The device is in the form of a finger manner that the cable cannot become sharply ring which fits on the first index finger and bent and thereby possibly broken. The de- to which is fastened a clip for holding a cig- vice consisting of an arm and two clamps is arette in the desired position. This should illustrated in detail above. It is of great interest the modern woman. value in connection with instruments which are constantly being moved about as is an electric pressing iron.

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This new patent covers in detail a device for testing small dry cells and batteries such as are used in flashlights. A sliding contact No. 1,514,885, issued to F. A. Bigler, relates member touches the carbon or positive pole to an improved trunk to be mounted on the of the battery, while a stationary contact rear of automobiles. This container is pro- connects with the zinc or negative pole. A No. 1,504,311, issued to C. F. Bailey describes vided with a compartment at one end in sliding contact on the movable block connects a new type of rotary electric razor. A small which tools for use on the car are to be the point on that block with different lamps motor is contained in the handle through stored. The remainder of the trunk is de- located on the end of the board. These con- which a series of gears rotates a cylindrical voted to the carrying of various travelling tacts are so placed that a battery of a cer- blade. The slots in this blade are sharpened necessities. A double purpose is thus served tain strength will energize a bulb of its own on one edge and so designed as to remove by a single container. voltage. the hair without danger of cutting the skin.

www.americanradiohistory.com Science and Invention for April, 1925 1233 Scientrific A MATCHLESS MAID 11 11,,,,,,,,,,,111111111 1,,,11,,,,,,,,.1,1.,11111,,,,,,,,,,,,,,,1111,,,,,1,,,,,,,,,,,,11111,,,,,,,,,,,,, THE SELL WAS ON DARIUS had been dis- TEACHER : "Willie, can you tell me how First 1Pr-face $3.00 The Freshman Science Class matches are made ?" cussing the gravity, or Daniell's cell. WILLIE: "No, Ma'am. But I don't blame A FAIR CONCLUSION "Now," said the Professor, "can anyone you for wanting to know." PROFESSOR: give me another name for the Daniell cell ?" TEACHER: "Why, what do you mean ?" "And what has All was quiet for a moment, then a voice WILLIE: "Why, Mother says you've been chemistry giv- from the back of the room replied: "The trying to make one for over a year. " -H. en us ?" Lion's Den." -Julia M. Sharp. Earl Ballantyne, Reporter No. 17042. STUD E "Most of our THE FAST SET IS IT 20,000 FEET IN THE AIR? blondes." - Abc The engine In the "Liber- Mayes. room woke up. ty," Dec. 13, 1924, Reporter N o . 17592. "Say, ' said may be seen the Steam, "that's a following s e n - fly wheel you've tence - From the been running Czecho - Slovaki- around with." an: "Well," said the "And yet those HE WAS POSITIVE Governor, slowly, are the odds of NUT: Judge Spark is a human dynamo. "is that any call aerial guns every- He electrified the courtroom in his opening for you to pop where in the war speech." off ?" departments of the world today against TuT: "What's he doing now ?" "Pouff, pouff," broke in Smokestack, Smith. twenty thousand foot airplanes." Gosh! but NUT: "Charging the jury."-Frank "don't come to blows ! Of course, he's a fly ain't science wonderful.-Conrad Philbreck. wheel, but anyone knows that the Governor 1.111,,,,111111111,,,11111,,,11111.,111111111:111,111111,,,,1,,,1111111111111111:,,111111111111111111,,,,,_ can hold him down. Let him chase 'round ORANG him, who cares ?" ANY RELATION OF THE E receive daily from one to with OUTANG? "I run 'round with him too, and he doesn't two hundred contributions to hurt me," said the belt, feeling himself slip- Two young girls were watching the kanga- this department. Of these ping. roo cavorting about his pen at the Park Zoo. only one or two are available. We "Yeah, Belt's stuck on him," said the One of them asked, "What is that animal ?" desire to publish only scientific humor Resin. Her friend replied, "Oh, that is one of all contributions should be origi- and "Who- o -o -ee ! so that's it," said the whistle them Australian Boomerangs." -Jack L. nal if possible. Do not copy jokes sarcastically. "Not worth gettin' steamed Baker. books or other publications from old about 1 I'm tired -toot, toot ;" and with this as they have little or no chance here. he pulled the crown sheet about him and DEWEY PLUGGED A CAVITE By scientific humor we mean only such went to sleep. (CAVITY) jokes as contain something of a scien- "Oil right, oil right !" said the Fly Wheel tific nature. Note our prize winners. "I'll promise to cut fast JACK : "Gee, you might think a dentist hastily, out this was a civil engineer." Write each joke on a separate sheet life "; and the quarrel ended. -C. S. Garri- and sign your name and address to it. JILL : "Well, the may do a certain amount son. of bridge -work, but he's not so civil about Write only on one side of sheet. We unaccepted jokes. Please it. " -I. H. Rothenberg. cannot return A PLUG HAS TO do not enclose return postage. SOMETIMES PULL IT SOME JOKES ARE PETRIFIED All jokes published here are paid BILL: "Say do you know an easy way to OF ANCIENT HISTORY : "Why do for at the rate of one dollar each, be- TEACHER find the horse -power of a car ?" we call the first period of civilization the side the first prize of three dollars for the best jokes submitted each JONES : "No. How ?" stone age ?" BILL: "Just lift the hood and cough the JOHN : it such a long month. In the event that two people "Because existed "plugs. " -Robert E. Conrath. time ago that it has become petri send in the sanie joke so as to tie Clarence Tibbs, Reporter No. 17,314. for the prize, then the sum of three dollars in cash will be paid to each one. IS MARRIAGE A SAFETY MATCH? A COME -DOWN QUITE TEACHER : n , MEDICAL P R O- "What are safety % í rESSOR : "What is DID IT FRACTURE HIS CRANIUM? matches ?" first thing you : the AMERICAN: "Yell, my poor friend Pat STUDENT would o i f a pa- "Safety matches was killed by a revolving crane. ". tient of yours are matches that ENGLISHMAN : "My, wot fierce birds you were blown into have in America. " -Paul A. Flanagan. can be used on all the air by an ex- occasions, like in- plosion?" vestigating a gas MEDICAL STU- A CHIMNEY POT HAT OR A JACK leak, etc. " -Wil- DENT : "Wait for POT? liam D. Hoy, Re- him to come porter No. 16951. down. " -H. Earl DEALER TO PROSPECTIVE BUYER : "Can I Ballantyne, Reporter No. 17042. sell you one of these new style plugs ?" ANOTHER? CUSTOMER: "No, I haven't the jack." - CAN'T YOU INVENT WITHIN THE LAW Robert H. Lyman. YANK : "Compose a sentence containing the word 'invention'." OFFICE GROUCH : "There is only one way DUTCH : "Mine neighbor's son, Chon, make aviation safe." to APPLIED CHEMISTRY clapped at mine door. I say, 'Come in.' His FRIEND : "Yell ; what's that ?" TEACHER TO FLAPPER : "What is the sym- Vell, in vent Chon."-Abe Mayes, Reporter OFFICE GROUCH : "Have some good law- bol for platinum ?" yers prove that the law of gravitation is No. 17592. FLAPPER : "Engagement ring !" -Hilda unconstitutional." -Jack L. Baker. Carroll. SUCH IS LIFE A SLIPPERY SUBJECT In many parts of Mexico, hot and cold JACK: "I read that they are grafting ruba KEEP US springs are found side by side. One can ber- plants in banana trees." AWAKE see native women boiling clothes in a hot JIM : "What for ?" spring. rubbing them on a flat rock, and AUNT : "Won- JACK : "To make non -skid banana peels." rinsing them in a clear, cold spring. -Peter G. Nickles. der what makes A visitor watched this process for some me sleepy when I time and then said: MY STARS listen in ?" "I suppose the natives think Old Mother ANNA : "Prob- SON: "Dad, did you ever ride on stars?" Nature pretty generous, eh ?" ably the ether." - senor," replied his host, "There is DAD : "No, Sonny, why did you think so ?" "No, Stanley Rider, Jr. no SON : "You told yesterday about people much grumbling because she supplies hitchin' wagons to 'em."-Win. Dreyinin. soap." -John 1V. Sheen.

www.americanradiohistory.com 1234 Science and Invention for z1 pril, 1925 .02:/4,,,, ós.aZed`./ZOOr f rTh

^''.r''yriY'..e^'L''':/'.'L'v'''LLLLY'YL'L''S'rJ''L''S''''''L'`L'.Y'L''''LLL' / lrry' LL.rv.?Rr.arr...2ranyy'.r lr.r 4!Oq? : The "Oracle" is for the sole benefit of all scientific students. Ques- 3. Sketches, diagrams, etc., must be tions will be answered here for the benefit of all but only matter of suffi- on separate sheets. Questions addressed to this department cannot be answered by mail free of charge. cient interest will be published. Rules under which questions will be an- 4. a quick If answer is desired by mail, a nominal charge of 25 cents swered: made for each question. is 1. Only three questions can be submitted to be answered. If the questions entail considerable research work or 2. Only one side of sheet to be written on; matter must be typewritten intricate calculations a special rate will be charged. Correspondents will be or else written in ink, no penciled matter considered. informed as to the fee before such questions are answered.

VELOCITY OF LIGHT stars in directions at right angles to that of the again observed. By this method, it was found earth's motion have maximum displacement. It that it took light one second to travel 313,000 (1817) Q. 1. Bernard Steinmetz inquires as is thus at once seen that the apparent position kilometers. to the different methods used in determining the of the star changes slightly as the earth moves Foucault's method was devised and carried out velocity of light. from one part of its orbit to another, so that in 1850. The essential A. 1. The earliest attempts to solve the prob- features of his apparatus by careful determinations of its apparent position consisted of concentrating a beam of sunlight lem of the velocity of light were made at the made during an entire year, the maximum dis- through a narrow Florentine Academy by Galileo. His method was slit and passing it through an placement or aberration constant may be deter- inclined plate of glass from which it passed to place a light on a distant hill, uncovering the mined. This aberration constant from recent through a lens to light for an instant and measuring the interval a mirror revolving about 800 observations has been found to be 20.492 ". As times per second, the light from which was of time elapsing for the return flash. This ex- it is well known that the mean velocity of the focused upon a concave periment did not prove anything because the dis- mirror whose center of earth in its orbit is 18.51 miles per second, the curvature was exactly at the center of the rotat- tance between the two stations was not great velocity of light can be determined from the ing mirror. appreciable Reflection took place from the inclined enough to detect any time. relation : (20.492 equals 18.51 divided by V. plate of tan ") glass and by placing the eye near it, a The result gives 186,400 miles per second as the certain angular displacement could be noticed. velocity of light. By this means, In 1849, Fizeau, following a method of meas- velocity of light to be less in l water than urement which did not involve astronomical means, in air,

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COLLIMATOR Interesting Articles to E .. Appear In April Issue of "The Experimenter" An astronomical method of measuring the The above illustration shows Fizeau's purely Electrostatic Loud Speaker. speed of light is illustrated above. This was physical method of measuring the velocity of By Vilh. Wardinghausen, used by Roemer in 1676. This indicated a speed of 186,900 miles light Copenhagen, Denmark. per second, quite accurate considering the result method used. of the greatest signifieance in determining Chemical Laboratory Manipulation. the nature of light. More recently, Michelson has done some very excellent work in determining By T. O'Conor Sloane, Ph.D. the nature and In 1676, Roemer, a Danish astronomer, found velocity of light and we would advise our readers to read of Isis researches. See that it took light a measurable amount of time Making a Mercury Vapor Ultra- Violet article from one point to another. Every time in our next issue. to pass Lamp. By Raymond B. Wailes. it revolves around the planet, the first satellite MAGNETO TACHOMETER of Jupiter passes into the planet's shadow and disappears or. is eclipsed. Cassini several years Experimenter's Glass Blowing Tools. (1818) Rufus Osbahr, Hazleton, Penna., wants before Roemer's discovery, had carefully deter- How to Make a Ring Armature Dynamo. to know : mined the periodic time of the satellite and had Q. 1. Kindly give me some information on prepared tables showing when the eclipses were Getting On the Air. the magneto tachometer? slated to take place for several years ahead. Upon A. 1. The magneto P. Peck, Assoc. R. tachometer consists of a comparison of these tables with the recorded times Bÿ A. 3MO, I. E. magneto generator used in conjunction with an of observed eclipses, Roemer found that they were electrical indicating instrument. The magneto is observed sooner than predicted when the earth a direct current generator having a permanent was on the side of its orbit nearest to Jupiter, magnet field and a revolving armature provided and later than predicted when it was on the oppo- with a commutator. The entire magneto circuit site side. His conclusion was that the discrep- is designed so as to procure uniform flux condi- ancy was due to the velocity of light. His and was a purely physical one, evolved a device tions in the air gap, while the armature is con- observations indicated that light requires sixteen which gave approximately 186,900 miles as the structed to have unusual mechanical strength. minutes to cross the whole of the earth's orbit velocity of light. Using a telescope and colli- The commutator and brushes are definitely ad- or approximately 8 minutes to go from the sun mator set up at a distance of 8.633 kilometers justed in position and require no further atten- to the. earth. In exact terms, 489 seconds was (more than five miles) apart, a beam of sunlight tion, except at long intervals. Ball bearings found to be the time required to traverse the (L) sent through an opening in the side of the support the armature which permit extremely 92,900,000 miles between the sun and earth, thus telescope was reflected by a small oblique plate free rotation. The magneto tachometer gives very making the velocity of light 186,600 miles per of glass (G) so that it passed directly out through accurate readings of speeds and can be used on second. the lens of the telescope to the distant collimator. machines having a speed between 1,000 and 2,500 It was not until 1727 that further work was The collimator consisted of a lens and a mirror revolutions per minute. In case the speed is done to calculate the velocity of light. The Eng- placed at its focal point and was so adjusted higher, proper ratio pulleys, gears or chain drive lish astronomer, Bradley, discovered that the stars that the beam of light was reflected directly back should be used to reduce the speed. The chief in any given part of the heavens were appar- into the telescope again. This light passed through advantages of this type of tachometer are its ently displaced from their mean positions by an the plate of glass (G) and was received by the accuracy of reading which is of the highest exceedingly small amount which depended upon eye at (E). Thus, the light came to the eye (E) order; its compactness and easy application and the position of the earth in its orbit. This phenom- after traveling to the distant mirror (M) and the fact that it can be used to transmit the enon, which is known as aberration, was explained back again. required information to any reasonably remote upon observation that the position of a flag on a In the telescope at (S) a smallopening, which point, because it is only necessary to keep the small boat depended upon the velocity and direc- was alternately opened and closed by the teeth electrical resistance of the connecting leads or tion of motion of the boat as well as on the of a cogged wheel (W), lay in the path of the cables nearly constant or within prescribed limits. wind. He finally concluded that the apparent light. Rotating the wheel slowly, the light from In a test recently conducted with the standard direction in which light comes to the earth from (L) passed through a gap between two teeth, to magneto tachometer which was run continuously a star must be affected by the velocity of the the distant mirror and hack again through the for 700 days without giving the commutator or earth just as the apparent direction of a breeze same opening to the eye at (E). Fizean's appa- brushes any attention whatsoever and without to a man in a boat depends on the motion of ratus consisted of a wheel having 720 teeth lubricating the bearings. the greatest variation the boat. making 12.6 revolutions per second. At this in electro- motive force was found to be but 0.25 When the earth is moving directly toward or speed, the light was completely eclipsed, in other of 1%. This is truly a remarkable performance. away from a star, there is no evidence of dis- words. was absolutely cut off. An increase or the speed of rotation being 2.000 revolutions per placement or aberration, while at the same time decrease in the speed allowed the light to be minute.

iii ,,,,i,,.. FREE INFORMATION IF you want additional information concerning any of the subjects illustrated and described in this number of SCIENCE AND INVENTION we shall be glad to give you other data we have at our command. To make this work as easy as possible for our editors, please be brief. Write only on one side of the paper and state exactly in a few wo -ds just what it is you desire further information on. We have the original manuscripts and drawings of many of these articles in our files and can furnish much additional data in most cases. Please do not fail to send stamped and self -addressed envelope. Make all questions concise and specific. - Address all inquiries of this nature to INFORMATION EDITOR c/o Science and Invention, 53 Park Place, New York City.

www.americanradiohistory.com Science and Invention for April, 1925 1235 RING MAGNET 5% carbolic acid CLAY FOR PAPER 15% tannic acid (1819) Q. 1. Gerald Farrar, Columbus, Ohio, 20% sodium acetate solution (1822) Gerald E. Davis, Bangor, Maine, states: wishes to know where the poles of a ring magnet 10% iodine solution It is generally understood that foreign clays are bet- are situated. Citric acid solution ter than American clays for use as fillers in the A. 1. It is possible to magnetize a uniform 10% potassium hydroxide solution manufacture of paper. Is this assumption true? ring of iron or steel by means of an electric cur- A. 1. That American clays compare favorably rent so that the lines of force are circles prac- In a similar test in which the sheet was immersed with foreign clays as fillers in making paper is the tically entirely within the substance of the ring. in 33% potassium hydroxide solution for one hun- conclusion drawn from an investigation of clays In such a case, there are no poles in the magnet, dred and twenty days the metal showed a discolora- for this purpose made by the Bureau of Standards of as ordinarily understood, because there are no tion but there was practically no change in weight. the Department of Commerce. The amount of clay places where the lines of force enter or leave the The only chemical reagent so far examined, which retained in the paper, and in general the quality of ring. Such a magnet has slight, if any, external at ordinary temperatures attacks this metal appre- the paper, were found to be the same for both field of force and would have little or no polarity ciably, is hydrofluoric acid, but when both the metal American and foreign clays. A slight advantage for effect on a magnet needle near it. However, and acid are pure this action is very slow. A mix- the foreign clays was shown by the color and grit in case it is broken in halves, it will show four ture of hydrofluoric and nitric acid will attack the tests, but the Bureau does not consider it sufficient poles as in every other pair of magnets. metal rapidly, causing it to go into solution as tan - to justify the consideration of only these properties talum fluoride. In the case of high boiling point in selecting clays. acids or solutions, a slight action may develop at the Most of the tests were made in the experimental boiling point; for instance, concentrated sulphuric paper mill at the Bureau of Standards, although acid appears to attack the metal very slowly at its duplicate tests of parts of the work were made in boiling point. The same would apply in the case of a commercial mill. Eight representative clays were other concentrated solutions of the caustic alkalies used, and the study included a comparison of the at the boiling points of these solutions. amount of clay retained in the finished paper, the The following resumé includes uses to which the quality of the paper produced, and those properties metal has already been put and uses which its pecu- of the clay, such as grit, that might affect the liar properties might suggest. In considering the paper manufacturing process. Good agreement was UGes for this metal, the main points to be considered found between the results in the experimental mill are its high melting point, its resistance to chemical and those in the commercial mill. corrosion, its tendency to absorb gases when heat- Clays have long been used as fillers in making ed and the fact that it oxidizes when heated in air, paper, their purpose being to increase its opaqueness to a red heat. Among the uses for this metal may and to improve the printing quality of the surface. be mentioned the following: Paper makers in general have favored clays from Dental instruments and dental spatulas foreign sources, believing that America clays pro- Surgical tools duced inferior paper. The present investigation Pen points was made with a view to ascertaining whether or Filament wire for incandescent lamps or thermio- not this belief were true. nic Q. 2. Does oil paint applied to the surface of tubes fresh lime plaster affect its setting qualities? A. 2. That oil paint applied to the surface of nimnmm:,mTmimmrtnnnnmmnunnmuuuwn1u11u1um111w1111mn1111 .:1rr.11 1111.11111r fresh lime plaster has a decided tendency to hinder the setting of such plaster is one of the conclusions IMPORTANT s drawn from a series of tests made by the Commerce 9 Department's Bureau of Standards. The setting TO NEWSSTAND READERS of the plaster results from the absorption of carbon dioxide from the air and the resulting change of T N order to eliminate all waste and un- é A ring of steel may be permanently magne- 0 the hydroxide, or lime, sold copies it has become necessary to slaked into calcium car- tized. The lines of force in this case are cir- supply newsstand dealers only with bonate. cular in form and are illustrated above. the ac- This absorption of carbon dioxide is very greatly tual number of copies for which they have hampered orders. This makes it advisable to place by the paint film, the Bureau finds. It an order with your newsdealer, asking him is retarded, but not seriously, by a finish coat, and to reserve a copy for you every month. takes place more rapidly in lean mortars than in TANTALUM Otherwise he will not be able to supply rich. The combination of a finish coat with a film your copy. of oil paint on top of it was subsequently tried, For your convenience, we are and (1820) Martin Nelson, Rochester, N. Y., requires appending herewith a blank which we ask was found to prevent the absorption of carbon information concerning tantalum, its properties and you to be dioxide almost entirely, cubes of plaster in this good enough to fill in and hand way uses. to your newsdealer. He will then be in a showing no appreciable penetration of carbon A. 1. Tantalum of a purity of not less than position to supply copies to you regularly dioxide after a period of six months. 99.8% has a steel blue color when unpolished and every month. If you are interested in a nearly platinum white color when polished. The receiving your copy every month, do not TERRESTRIAL MAGNETISM steel blue color of the unpolished metal is probably fail to sign this blank. It coats you noth- due to a thin film of oxide on the surface. ing to do so. (1823) Q. 1. David McCarthy, Vancouver, Tantalum has a melting point of about 2850° C. B. C., desires us to print a diagram showing the Tungsten is the only metal which has a higher melt- poles and magnetic lines of force as understood ing point. to surround the earth. The specific gravity of the worked metal is 16.6. To A. 1. As a foreword, it is brought to your The metal is characterized by toughness and by Newsdealer attention that the magnetic and geographical poles great ductility and malleability. and may be submit- Address of the earth do not coincide. The diagram shows ted to the various mechanical working operations what is the probable form of the lines of magnetic as ordinarily applied to the more common metals. Please reserve for me copies of force around the earth. The direction of these The tensile strength of the drawn wire may reach SCIENCE & INVENTION every month lines of force is known only at the earth's sur- 130.000 pounds per square inch. until. I notify you otherwise, and greatly face. What the magnetic condition of the interior The linear coefficient of expansion is more than oblige, of the earth may be is a matter entirely unknown. that of molybdenum or tungsten and only slight- By the use of the magnetic needle, the resultant ly less than that of platinum. Name force of the angles of declination and deviation It has been found possible to seal this metal is plotted. into glass. Address Of course, when we speak of the magnetic north The electrical resistance is quite high, being pole, and call the pole of a bar magnet pointing about eight times that of copper and about three towards it, a north pole, it really is a south (north times that of tungsten. seeking) pole. Convention, however, assures us Of all metals, tantalum is one of the most re- that we are not wrong in using the universal sistant to wet chemical corrosion and in this Plates and support wires for the thermionic tubes terminology. respect it is the equal of platinum or gold. It Hypodermic needles is, however, subject to oxidation when heated in Cathodes for use in electrochemical analysis a Analytical weights, laboratory dishes, spatulas, the air, the surface becoming blue at tempera- in a ture of about 400° C and nearly black at a stirrers and other devices which perfectly somewhat higher temperature. If heated to a acid -proof metal would be more suitable than higher temperature, the metal gradually burns to porcelain or glass a white oxide. Parts of scientific instruments Tantalum also combines at elevated tempera- Acid -proof pumps and parts of commercial chem- tures with hydrogen or nitrogen. It will absorb ical equipment seven hundred and forty times its own volume of Electrolytic valves for the manufacture of rectifi- hydrogen, producing a definite compound known ers for obtaining direct current from alternat- as tantalum hydride which is a course -grained ing source as in battery chargers, electrolysis brittle compound. apparatus, radio, etc. While pure tantalum is soft and ductile it becomes harder when it has absorbed gases and may become brittle if the quantity of absorbed SOLAR HEATER gas becomes too great. (1821) Irving N. Cox asks : Is it possible to utilize Tantalum burns when heated in chlorine gas, a system wherein traveling reflectors follow the producing the volatile pentachloride. Aqueous its solutions containing chlorine, -however, have no course of the sun and reflect heat on tanks of action on the metal. Tests made with sheets of water to generate steam to be used for driving tur- tantalum in which the sheets were immersed bines connected to generators? either wholly or partly exposed to the air in the A. 1. While your idea is practical and will following reagents, showed no gain or loss in work, there seems to be very little inclination on weight at the end of fifty days: the part of practical engineers to utilize this form of power as long as the coal mines and oil wells Concentrated sulphuric acid hold out. The idea has been published several times Dilute sulphuric acid in various forms and is being employed to a small Concentrated hydrochloric acid extent in different parts of the world. Dilute hydrochloric acid Q. 2. Can power be obtained by using chimney Aqua Regia flues or tall smoke stacks and utilizing the power- Glacial acetic acid ful force resulting from the drafts set up? 10% acetic acid A. 1. Generally speaking, your second idea of 50% formic acid employing the power from the combination of the Magnetic lines of force surrounding the earth. 12% formic acid wind and drafts in tall stacks, is feasible. Most of poles 10% oxalic acid the power developed would come from the wind The magnetic north and south are desig- 85% phosphoric acid but little power would result from the attempt to nated by P and Pl. Line S -N indicates posi- 10% phosphoric acid use the drafts caused by the rising chimney gases. tion of compass needle.

www.americanradiohistory.com 1 236 Science and invention for April, 1925 wzrds 1.000 nthly Contest The Regular Departments Pay Prizes of Their Own, Authors on Contract Receive Their Own Rates; this, With Other Special Payments Makes the Total Paid for Articles in Excess of $1500.00 Monthly. FIRST PRIZE $100.00 FIFTEEN PRIZES OF $10.00 EACH Our Tests with Flettner Rotors, by Harold F. Richards, Ph.D 1189 Jupiter's Moons, by Miss Ada \Veber 1188 SECOND PRIZE $75.00 Plumb Fixtures, by Allen P. Child 1188 Protect Maps, by Raymond B. Wailes Will There Be Another Ice Age? by Dr. Gene Deachem 1196, 1197 1193 Jar Opener, by J. B. Roswick 1200 TWO PRIZES OF $50.00 EACH Push Pins, by J. W. Von Stein 1200 Super Charger for Automobiles, by J. H. W. Kerston 1190 Egg Holder, by J. B. Roswick 1200 The Ritz Super Het, by Charles Caesar Ritz 1227 Drawing Game, by J. W. Von Stein 1200 Liquid Determination, by N. C. McLoud THREE PRIZES OF $35.00 EACH 1204 Portable Electric Fan, by Otto Halmer 1204 Hotel for Bachelors, by L. Schumacher 1180 Coil Winder, by Charles Craft 1217 Capillary Attraction- Surface Tension -Cohesion, by Raymond B. Wailes 1212 Tray Heater, by L. B. Robbins 1217 A Four Tube Distance Getter, by Sidney E. Finkelstein 1226 Condenser, by Carlyle Weiss 1217 FIVE PRIZES OF $25.00 EACH Rubber Mallet, by Adolph Lonk 1217 Outdoor Scenes Duplicated in Studio, by Harry Van Demark 1183 Card Holder, by R. Kreig, Rep. No. 13307 1218 Portable Bed -room Outfit, by G. H. Waetjen 1210 Furniture Polish, by C. A. Oldroyd, Rep. No. 4433 1218 Metal Etching, by Joseph Crotty 1215 TEN PRIZES OF $5.00 EACH The Larmor vs. Heaviside Theory, by Dr. Joseph M. Howard 1220 Trousers and Raincoat (author please send Multiple WP e Meter, by Sidney E. Finkelstein 1228 address) 1200 Floor Waxer, by J. W. Von Stein 1200 FIVE PRIZES OF $20.00 EACH Hot Jar Carrier, by J. B. Roswick 1200 Axe Marks 25,000 Years Old, by John R. Howard, Reporter No. 5058 1181 Cleaning Camera, by C. A. Oldroyd, Rep. No. 4433 1217 Artists' Copying Device, by C. T. Stone 1203 Screw in Plaster (author please send address) 1217 Studies of the Plant World, by S. Leonard Bastin 1205 Pinchcocks, by C. A. Oldroyd, Rep. No. 4433 1217 Making Cactus Lamps, by Byron \V. Sieg 1214 Spring Substitute, by A. P. D'Ambra 1217 Hand -Painted Panels, by C. S. Stahl 1221 Water Pan, by Herbert E. Morris, Rep. No. 9363 1218 Coin Trick, by Dr. Albert Neuberger TEN PRIZES OF $15.00 EACH 1218 Inkless Pen, by J. Samachson, Rep. No. 10061 1218 Umbrella Hat, by L. Schumacher 1185 Local Rain, by J. Alfred Miller 1188 FIFTEEN PRIZES OF $2.00 EACH Telescope and Eye Distance Gauge, by Dr. Albert Neuburger 1192 Vacuum Sweeper, by J. W. Von Stein 1200 Advertising of the Future, by Hubert Slouket 1202 Hot Plate Lifter, by J. B. Roswick 1200 Convertible Chair, by A. L. Foxman 1204 Freezing Mixture, by Philippe A. Judd, Rep. No. 720" 1217 Electric Fireless Cooker, by J. W. Von Stein 1205 Cord Tightener, by Everette A. Peterson 1218 Magnetic Door Locks, by Philippe A. Judd, Rep. No. 7297 1214 Duplicator, by E. W. Kinner 1218 Sensitive Hygrometer, by C. A. Oldroyd, Rep. No. 4433 1216 Driving Screw, by M. G. Sperry 1218 Interesting Paper Models, by A. Gruntal 1216 Collapsible Tube 1;1.1:. by Leland B. Clark 1218 Emergency Pulleys, by Alvin Heduall 1216 (No further entries) ::II:IIIIIIIIII,11,11,,,,,111,1:111111111::11,::1::i:: :.::::: $ 13,320.00 in Prizes Paid Last Year ,' X j1TH the December issue our $12,000 a year prize contest esting and to otherwise excel in the reporting of science and inven- came to a happy conclusion. Not only did we pay out tion. Small wonder then that with the enthusiastic cooperation $12,000 in prizes as announced in our November, 1923 issue, of our thousands of Reporter- Correspondents, SCIENCE & INVEN- but we did actually pay out in prizes alone, not less than $13,320.00 TION today occupies an enviable position in the scientific press. to 1,112 winners. These prizes every month ranged from the first The $12,000.00 prize arrangement has worked out so satisfactor- prize of $100.00 down to the smallest prize winner of $1.00 each. ily during the year just closed that we have decided to extend it Up to the time of going to press, SCIENCE & INVENTION had no for another year: and we hope that our correspondents will be as less than 19,000 reporters scattered over every section of the globe. successful in winning prizes for the coming year as they have been These reporter -contributors have sent in an avalanche of material, during the past one. We wish to thank all of our friends for their and their efforts have been fruitful in that they have won prizes. cooperation and wish them the best of luck for the coming year. SCIENCE & INVENTION aims to print the new, first, if it i; iilter- Note New Prize Schedule

Here Is How You Can Get in the Contest: $12,000 or More in Gold 82 monthly prizes will be given as $1 2,000 or More in Gold follows: EVERY month SCIENCE AND INVEN- is IDEAS. These ideas will be handsomely TION pays $1,000 or more in gold in FIRST PRIZE $100.00 paid for. We have published a pamphlet prizes. Every text article published will SECOND PRIZE $75.00 showing the rules of the contest which we receive a prize -(most of the departments 2 PRIZES OF $50.00 each shall be glad to send to anyone free on re- have awards of their own which they give 3 46 35.00 ceipt of a postal card with your name and it every month). Ideas are what the Editors 5 " 25.00 address. The pamphlet gives full details, want. The ideas must be told simply, so that 5 " 20.00 " the rules and how to submit articles. The your mother or your sister can understand 10 " " 15.00 " magazine itself shows you what is wanted. '__ them -in pictures or sketches or both. But 15 " 10.00 " Study it closely and submit your ideas. the idea must be new and must have some- 10 46 " 5.00 " The closing date for all prize contributions thing to do with science or invention. 15 " 2.00 " is the 15th of the month preceding date of The Editors want pictures and sketches - 15 66 1.00 " issue, i.e., the 15th of April for the June must have them -hut what they want most issue, the 15th of May for the July issue, etc.

WILL YOU BE OUR REPORTER? C1eilCe and CORRESPONDENT REPORTER'S N connection with our $12,000 prize contest announced herewith, it goes without saying that you will have to IDENTIFICATION do a little work in order to win a prize. The Editors do not wish to make it hard for you, quite the contrary. Invention We want pictures and ideas and we cannot have too many of them. i Q o¡A Herewith is reproduced our reporter's card. Up to now we have issued over19,000 _ of these. Note in p/ our awards how our reporters are along. We shall be glad to send the reporter's card free winning prizes right THE BEARER OF THIS CARDe.L-!_ -:ki A'.NA_`L27/J/ to anyone who makes an application for it. By means of this card you will be able to secure entry into industrial IS AN AUTHORIZED CORRESPONDENT - REPORTER OF plants, business houses, motion picture studios, steamships, docks, public buildings, etc. This reporter's card will SCIENCE and INVENTION MAGAZINE an open one a Prove sesame to you in many instances. Every card is numbered and only is given to correspondent. THE PUBLISHERS OF SCIENCE AND INVENTION WILL A postal card from you and a request for this reporter's card is all that is necessary to obtain one. It will be APPRECIATE ANY COURTESY EXTENDED THEIR sent to you by return mail. With it we will send you a pamphlet giving rules of the contest and how to proceed REPRESENTATIVE. in order to get photographs, to send in sketches, and other information in order to obtain a valuable prize. Not Ex RIMENTER P LIS CO.. only will this card help you to obtain material for this magazine, but it will train you to become a news gatherer, and will be the means of helping you to earn a good deal of money during your spare hours. Address Field Editor, SCIENCE AND INVENTION, 53 Park Place, New York E

www.americanradiohistory.com Science and Invention for April, 1925 1237 FREE 20 Book Finishing It Tells: How to stain wood artis- tically. How to refinish o l d wood in stained and enameled effects. How to remove old paint and varnish. How to fill unsightly germ - catching cracks in floors and woodwork. How to secure a beautiful enamel finish.

It Tells: How to make your home more artistic, cheery and inviting. How to keep floors, woodwork and furniture in perfect condition. .-' How to finis!: soft and hard woods. ;._u_ If you have a hobby for making cabinets, furniture, radio boxes, etc., -you will find our Book invaluable. For, naturally, you want to give your handiwork a beautiful finish. Our Book gives complete instructions for finishing all wood-hard or soft, old or new. Tells how to make soft woods beautiful as hardwood. It is the work of experts -beautifully illustrated in color. Gives covering capacities-- includes color charts, etc. Use coupon below. DY (Penetrating) Johnson's Wood Dye is very easy to apply. It dries Johnson's Wood Dye is a dye in every sense of the in four hours and will not rub off or smudge -pene- word. It contains no finish whatsoever. Like most trates deeply, bringing out the beauty of the grain. first class products it answers one purpose only -it Johnson's Wood Dye is made in 17 popular shades as dyes the wood -the finish must be applied over it. follows : We recommend Johnson's Varnishes or Johnson's Polishing Wax. No. 128 Light Mahogany No. 125 Mission Oak Stores displaying the Johnson Service Department No. 129 Dark Mahogany No. 130 Weathered Oak Sign carry a complete stock of Johnson's Artistic No. 127 Brown Mahogany No.110 Bog Oak Wood Finishes and will be glad to show you finished No. 329 Red Mahogany No.172 Flemish Oak wood panels answer questions how finish No.120 Fumed Oak -and on to No. 178 Brown Flemish wood the proper way and give you a copy of the No.123 Dark Oak Johnson No.126 Light Oak No. 131 Walnut Book. No.124 Golden Oak No. 140 Early English No.160 Brown Oak No. 180 Gray S. C. JOHNSON & SON, Dept. s. I. 4-2. RACINE, WIS. SERVICE "The Wood Finishing Authorities" (Canadian Factory- Brantford) e darkened or inter- DEPARTMENT All shades may be easily lightened, .- Please send me free your Instruction Book on mixed. Full directions on every lábel. Select the Home Beautifying and Wood Finishing. I enclose jONNSO 10c to cover postage and wrapping. shade of Dye you want from the list above and order MY DEALER IS o it from your dealer by name and number. ARTISTIC My Name WOOD I S. C. JOHNSON & SON, Racine,Wis., U. S. A. FINISHES Address City and State " The Wood Finishing Authorities"

www.americanradiohistory.com 1238 Science and Invention for .9pril, 1925

,llI11111,2®,m1aMm1.m,n.1111.R1111111,1n,n,,,.,1,1,1,111111;,1111,1 ,,, ,,,i,, , ,11,,,11.11.,.11M,111,1/1,111111 _ 111111,10,..1,11111,,,11111111.. cton- NackeR-Aaw90 Secweas (Continued from page 1199)

,,,,u,r1111111,1=,1rtrt11a,1111,111111,111111,,,,,,,11111111111111111111111.0,0111,111.,1 ,,-7,1,11111,,,11IImIuIrrrm M1 1 11 11, mrmssammmaani11.11111,,,I11,111,111Wllt111,1,11

method of working them. Then, seeing that Oriental splendor and at last introduced her glance had fallen on one of Doctor him into the chamber where the wireless Hackensaw's wireless cipher machines, he apparatus was installed. explained to her how this device could be "Your excellency," said the servant, "here used to send secret messages. is the gentleman." As he spoke, the young woman became Evidently Julius's fair customer was a lady intensely excited and threw back her veil of the highest rank. This time she was un- in order to get a better view of the appa- veiled, and as she rose from the divan to ratus. Julius looked up at her, and was greet him, Julius perceived that she was amazed to perceive one of the most beauti- even more beautiful than he had imagined. ful women he had ever set eyes on. For a Never before had he seen such a houri. moment their glances met, and then the To avoid showing his embarrassment, young lady carefully readjusted her veil Julius approached the wireless set to ex- BECAUSE OUR NATIVE again. amine it, but she hastily plucked him by HAWAIIAN INSTRUCTORS But she had smiled at him and Julius saw the sleeve and drew him back. the smile with a thrill of pleasure. "Hush !" she said. "You must not make WILL SHOW YOU HOW! He took the greatest pains to explain to Be the Most Popular Member of Your Set. Play' ",What'll any noise, or my father may hear you. He I Do ", "Memory Lane", "Lazy ". All the late song and her in detail the working of the cipher has returned unexpectedly and is in his dance hits. You can play First Selection in Half an Hour and Harmonious Chords at ONCE. Entertain your machine, and as she ordered two sets, he room. Perhaps, however, you can discover friends Play for money. Don't be a wallflower. Be the gave her a practical lesson Life of the Party. then and there, the trouble without switching on the cur- FAMOUS HAWAIIANS TEACH YOU making her change the combinations and rent. If not, you must return tomorrow. TO MASTER QUICKLY THEIR SE- work the set herself so as to be sure that Julius leaned over and examined the in- CRETS OF THIS FASCINATING MUSIC she The instructions you receive from such world famous ex- understood his directions. strument, but everything appeared in per- perts as Lawrence Kalaluki, Walter Kolomoku Frank She made one stipulation was that fect condition. The Forera, Carl Seville and others are invaluable. NO -it young lady stood be- OTHER Conservatory can even begin to give you the Julius should call her up every day at noon side him, watching him, and insensibly expert teaching and knowledge you gain through us. and speak a few words to her in order to ONLY 4 EASY MOTIONS -to learn to be able to Julius's arm began stealing gently around play any music, popular dance, classical, native Hawai- insure that the apparatus was working prop- her waist. She did not appear to notice it, ian Airs or old time melodies and hymns. Just think of it' You need never have read a musical note in your life. erly. It is needless to say that young Mc- so Julius, growing bolder, pressed her to I 'or that matter, even though you haven't the slight- Masher, always ready for an adventure, est knowledge of any musical instrument, weguar- him. Their eyes met, and she yielded grace- antee to teach you to play just like native Hawaiians. readily gave the required promise. fully." Her lips and his met in one long y U]]J NSW INVENTION He had explained to her about the tuning - sweet kiss, and then she allowed her head iI ' dI, ,G. .. MAKES IT EASY in. In Doctor Hackensaw's I 1« Our method is so sim. first experi- to sink upon his shoulder. pie, plain and easy that ment, it was necessary you begin a piece your first before sending a mes- They were disturbed by a sudden noise, lesson. In half an hour you sage to tune in each of the ten different and looking up Aïssa, for that was the young can play it! Thousands of successful students prove wave -lengths separately in order to be sure lady's name, or Ayesha, as it is usually this to be true. No matter that each wave -length how little your knowledge of the receiving set Anglicized, perceived her father glaring at of music may be, you can would correspond exactly with the corre- her with a glare of 110 Othello-power volt- learn to playby our plain, easy picture method. sponding wave -length of the sending set. age. COMPLETE CONSERVATORY COURSE In his improved apparatus, however, the ma- "Ha !" cried he. "So! so ! my fine young You get 52 complete essons An entire conservatory course. Nothing is omitted. Success is assured. Real chines were so accurately made that one fellow! Do you imagine you can come into Hawaiians instruct you. This is single tuning sufficed to bring all ten wave- a man's house the only Conservatory teaching ;I i like this and make love to his Hawaiian Guitar exactly as lengths in perfect accord with the ten of daughter, and then escape scot -free? Not played by the Hawaiians. It is your good fortune the other set. if I know myself 1 Hey, guards, come here! as well as ours, that these For a week so, Native Masters of Hawai- or regularly, every day at Seize me this dog of an unbeliever, and I'll ian Guitar come to this noon, Julius exchanged secret messages with make an example of him !" Conservatory to teach. his WE FURNISH YOU beautiful client. At first the messages "Quick Julius!" cried the girl. "I will WITH-EVERY. related principally to the working of the try to hold my father while you escape by THING. When you en- apparatus, but it soon drifted into conver- the other door. He me, he roll as a student in this con- won't hurt but servatory, you receive sations on general topics. It must be con- would kill you if he got hold of you now I" FREE a handsome, sweet toned, Genuine Hawaiian fessed that Julius flirted outrageously with There was no time to lose, so Julius with Guitar -valued at $l5.00 -52 specially arranged lessons, the lady, yet she didn't seem to mind, but a bound flung open the rear door and scram- as well as all the necessary Picks, Steel Playing Bar, etc. There is NOTHING extra to buy; everything furnished. answered his lone messages with peals of bled downstairs. He heard voices behind Yours Free! We mean silvery laughter. him, and his pursuers were so close upon it.There are no strings tied to this generous offer. You And then one day came a message that him that in his hurry he went down one get it absolutely free as made high. him soon as you enroll for our Julius's heart beat She told flight too many and found himself in the course of 52 easy lessons, her set was not working very well and she cellars. taught by real Hawai- ians. You can't possibly would like him to come and fix it. As men There was no possibility of repairing the lose, so mail the coupon at were not allowed come into harem, once for full information. to the error, and it seemed hopeless to seek a hid- GUITAR WORTH he was to meet her attendant at the Mosque ing place here. Nevertheless, it was his SIS.AO. Yes, that is the of St. Sophia, and the attendant would see only hope, so he entered one of the cellars price charged in the music atores Tor these beautiful Hawaiian Guitars. We can afford to givethem away free to conducting him to the lady's palace and and perceiving a trap -door in the floor, he of charge to every pupil because we manufacture them smuggling him in. "Above all things be very lifted it up and was delighted see in huge quantities in our own factory, which is the to a sheet largest stringed instrument factory rn the world` prudent !" she said ; and then she switched of water a few feet below him. SWEET TONED. You will het the same off, while he vainly tried to obtain further "The Bosphorus!" he cried gleefully. "I haunting, soothing, plaintive fascinating tunes that the real native Hawaiians get on these particulars. atr. Saved !" For he understood at once that same instruments. Plays any kind of music. Mc- 40,000 pupila prove all our claims are true. Sharp at the appointed time young this must be the famous sheet of water that Masher found himself at the door of the washes the walls of the residences of many SPECIAL COURSES mosque. The attendant was waiting, yet of the wealthy inhabitants of Constantinople. UNDER FAMOUS TEACHERS, TENOR BANJO VIOLIN, BANJO - UKELELE AND UKELELE appeared not to notice him, but as she walked Julius was a good swimmer and escape past him, she whispered: seemed now assured, for it would be mere "Follow me quietly at a distance !" child's play to swim in the dark to some boat TEAR OUT AND MAIL The affair was beginning to assume all the or to some deserted part of the city. rFIRST HAWAIIAN CONSERVATORY OF MUSIC, INc1 appearance of the regulation Oriental in- Without a moment's hesitation, therefore, I Dept.40 , 233 B'way, (Woolworth Bldg.) New York, N.Y. trigue, but Julius was ripe for any adven- he plunged into the water, pulling down the I Gentlemen: Please tell me all about your FREE HAWAI- I IAN GUITAR offer, and all about the course of lessons! ture. He waited until the messenger had trap -door behind him. He then started out I under native Hawaiian Instructors, by your patented and then followed her swimming, but had not gone ten feet picture method. 1 gone some distance when unobtrusively. he came to an obstruction -a row of piles Name - - -.._ 1 It was not a very long journey. Julius planted close together so as to form a wall. I Local I saw his guide enter the door of a very fine Nothing daunted, Julius swam along this I Address I mansion, and as the door was left open, he wall, but imagine his consternation when he found city & followed in, and found the attendant wait- himself back at his starting point ing for him. She led him through one without having found a single opening in apartment after another furnished with true (Continued on page 1240)

www.americanradiohistory.com Science and Invention for April, 1925 1239

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www.americanradiohistory.com 1240 Science and Invent!on for April, 1925 21 Jewel = Doctor Hackena vleo b'ecreto DEBAR _ (Continued from page 1238) the wall. He was, in fact, in a submerged knees before her stern parent, but with al prison, and strange tales carne back to his oath he caught her Direct mind by the hair and hurled from the -tales of the gay wives of sultans who her down the hole right on top of her lover. Maker would lure their sweethearts to visit them in Then he slammed the trap-door their palace, down and and when tired of them, would the sound of a key turning in the lock in- guard against indiscretions by throwing the formed Julius that unfortunate the trap -door was pad- men into just such flooded locked and that all hope of escape in that prisons as this one. When drowned, the direction was cut off. bodies could be thrown into the Bosphorus Julius, thrown back into and the water, had the men would appear to have met a some difficulty in disengaging himself from natural death by drowning. the girl whs.) had clung to him A second in affright. tour of the chamber convinced Luckily her haïk was still hanging from the Julius of the fact that there was no outlet, trap -door, so Julius made and her cling to it by diving he found the depth of the while he made a third tour of exploration water to be between ten and fifteen feet. around his prison. On the other hand it was impossible to For the f1: st time in his life Julius wished reach the trap -door to open it again. He he had never seen a wireless tried apparatus, and several times to spring up from the he cursed himself for a fool for ever water, but the hav- trap -door was far beyond his ing tried to send secret messages by wire- reach. He seemed destined to drown here less. like a rat in a trap. He could swim around But his was not a nature to give up tame- for a few hours -but after that? He shud- ly. Perhaps some outlet existed dered as he thought under the of the eventuality. water ? This, however, proved a vain hope, Just as he had given up all hope, the trap- but as Julius felt inch by inch door was stealthily around the opened and a face peered walls of his prison, he came to a corner 1OWN through. where one of the wooden piles appeared to America's greatest "Julius, is that you ?" came the sweet voice have rotted at the top. Watch value sent you of Aissa in a whisper. Young McMasher was "Yes; a muscular fel- for only $1.00 down! darling," he cried overjoyed. "Can low, and clearing away the rotten wood The balance you get a piece with in easy of rope to help me out ?" his fingers and aiding himself with his jack- monthly payments. The famous 21- "There is no time," she replied. "But take Jewel Studebaker Watch_ knife he, with considerable trouble, succeed:d hold of the end of my haïk. It is very in making an opening large enough strong and will to bare'y Insured For a do as well as a rope." allow the passage of his body. Then he re- Lifetime! With the words she took off the garment, turned You may choose from 54 new Art Beauty Cases for Aissa who was pretty nearly ex- and 8 handsome dial designs. 8 adjustments and letting down one end so Julius could hausted. to the second -for heat, cold, isochroniam and grasp it, she passed the other 5 positions. end around By great good luck the passage made led Sold direct from the maker-at lowest the hinge of the -door prices ever named for equal quality. Mail trap for support. into the open Bosphorus, and Julius had no coupon today for Julius, with aid, Free Book and Special Offer. this was easily able to lift trouble in swimming with the girl to a safe himself far enough to grasp the sides of spot for landing. Watch Chain FREE the -,n -door oper' For a limited time, we It would take too long to recount how are offering S;. A á a beautiful Watch Chain FREE. 'v that they Julius smuggled the girl on board an ocean Write now while this offer lasts. neitl)r father liner, but when the steamer had ar.. sailed that after- FOR BOOK er- noon, it carried with it a pair of loving ly hearts thankful for having WRITE momeo escaped from the Send at once and get a copy of this book -FREEf See many dangers that menaced them. the newest, beautiful advance styles in Studebaker to swii c' Art Beauty Cases and Dials. Read how you can buy ",,* neither Julius nor his charming wife a 21 -Jewel Studebaker Insured Watch direct from the startle. -r made maker- save big money -and pay for it in easy use of a wireless cipher ma- monthly payments. Get Free Chain offer while it lasts. Mail coupon today. STUDEBAKER WATCH CO. Dept. 1(97 South Bend. Indiana Canadian Address: Windsor, Ont. Ask for Ladies' Bracelet Watch Folder The ijI EY ri>sud, DezAh By JOHN MARTIN LEAHY ISTUDEBAKERfMtif, WATCH CO. Dept. K97 South Bend. Indiana (Continued front page 1195) IGentlemen: Please send me your Free Book o Advance Watch Styles and particulars of your down offer. $1., i tCandian your foundry Owe aWadeorr.. {-0 to believe it), and the return to Summer The sun rose Name above the white eastern hills Haven whilst it was still possible to take that morning about twenty minutes Multnomah past IAddress the through the pack. seven. I do not know that I have ever seen City In our plans there must needs be ample a sunrise more lovely than that was. All I Check here for. Irdlee' QState t here foe I allowance made for delays, and even then watch Folder. Jewelry Folder. the colors of the rainbow were in the sky there was no telling. No man living could and shone again the placid waters of Sum- (i ----- say what might occur. It was a case where mer Haven. what seemed to be time enough might easily "A happy omen!" said I to Frontenac, prove a time all to short, indeed. And, waving a hand in the direction of that pris- leaving these things aside, the ice conditions matic wonder. in sea - that through which the bhtlttiontah "Yes," he smiled. "The Parcae are, so would have to force her way are the most to speak, smiling upon us, Bond." terrible to be found anywhere in the Ant- I nodded at this pleasant conceit of his. arctic. The possibility of spending another Well did I know, however, and that from winter, and it was a possibility that we must bitter experience, how fiickle, treacherous, not blink, was not a pleasant one certainly heartless the Parcae really are. But to contemplate. And that A Complete Conservatory Course there was the possi- unpleasant thought, of course, I kept to my- 1 Wonderful home study music lessons under bility, too, that we might get away from self. By Mal great American and European teachers. find Endorsed by Paderewski. Master teachers guide and conci, Summer Haven only to (supposing our Well, we shook hands all around. you. Lessons a marvel of simplicity and completeness. return a late one) the Multnomah beset. Wntetelltngaseourse "Mush !" cried Louis Louisiana, cracking Any Instrument yyou are So we must, at all hazard, get an early his long whip. Harmony,Voice, Public School Munie, Violin, Cornet start for the Gardens of Paradise and be Mandolin, Guitar, Banjo, or Reed Organ -and we will semi And we were off ! our Free Catalog with details of course you want.Send now. on the return march as soon as was con- UNIVERSITY EXTENSION CONSERVATORY sistent with the full achievement of our pur- There were seven of us- Frontenac him- 147 Siegel -Myers Bldg. Chicago, Illinola self, Louis Louisiana, Wilbur Addison, Rich- pose. ardson Insure your copy reaching you each month. Sub- Well, we had done all that it was humanly Watson, 01e Hansen, Thomas scribe to SCIENCE & INVENTION -$2.50 a Loomis and myself. year. Experimenter Publishing Co., 53 Park Pl., possible to do. Now was the time for action N. Y. C. -to see what the Fates had in store for us. (Continued on page 1242)

www.americanradiohistory.com 1241 Science and Invention for April, 1925

au& taie, ,fou,ñaue dmanukt eft- TROPADYNE SUPERADIO OUTFIT

THIS Superadio 6 Tube Set brings in Station KFKX (Hastings, Ne- braska), 1200 miles, in New York City, clearly on a loud speaker, using $6050 only the small loop which comes with the outfit. The outfit advertised here is complete, SEND NO as listed below, everything needed is MONEY eluded, down to the last screw. The charts, blueprints, directions and photos furnished are so complete and explicit that anyone can build this set and have it working within a few hours. There is nothing additional to buy except the necessary batteries and tubes. Price includes mahogany cabinet and folding loop aerial. You can pay $150 or more for an outfit, or $200 or more for a set, but you cannot possibly buy a better set than this one TR OPADYlsI E Utmost sharpness -Cuts thru READ locals bringing in long distant THIS stations as if they were locals. Ease of Tuning-Only two dials. Tuned Intermediate Transformers; the only real BALANCED set of its kind made. Once transformers are tuned they need not be touched again. No. A4477 Your Money Refunded if this set does not satisfy you in all respects-if after 5 days' fair trial you do not proclaim the TROPADYNE the best radio set you ever listened to. Note These Important Features: equal to any REAR VIEW OF DISTANCE, VOLUME AND TONE QUALITY TROPADYNE 8 tube set sold anywhere at any price. LOOP RECEPTION -Outside aerial not to be used with this set -the complete loop is included in outfit. PERMANENT LOGGING OF STATIONS -Follow chart furnished; there are only two tuning controls and you will always find the same station at the same spots on the dials. Our log chart shows you at what point to find any station. MICROMETER VERNIER DIALS giving you the full advantage of the exceptionally sharp tuning. OUTFIT IS ABSOLUTELY COMPLETE -Drilled panel, Ma- hoganite Cabinet and everything else needed, except tubes and Set uses 201A or batteries. six UV-199 tubes. ECONOMY and SIMPLICITY -This is not a reflex, yet tubes do the work for which other sets require eight to ten. The Editor of Radio News Complete List of Parts: the Tropadyne: "Here is a remark- In the August 1921 issue, said this about 4 Tropaformers; 1 Standard Variocoupler; 2 Certified Low we recommend to our readers. It has several RICO able receiver which warmly 1 Transformer; 2 Jacks; 3 the first place only 6 tubes are used giving as Loss 23 -plate Condensers; Calibrated new and unusual features. In 2 Dials; 1 Rheostat; volume as the average 8 tube Heterodyne. The selectivity of this set is Fixed Condensers; 6 Bakelite Sockets; Vernier much now been done and unusual. Unequalities of the intermediate transformers have 1 Potentiometer; 1 7x24 Panel; 1 7x24 Mahogany Cabinet has been 1 away with by tuning each transformer. After the transformer Baseboard; 40 ft. Bus Bar Wire; 1 Folding Loop Aerial; Grid tuned, It can be left this way, no further tuning being necessary. Posts; Flexible Wire; 1 Bakelite for maximum sharpness and maximum volume. An- Leak and Mounting; Binding "This system makes 4 doz. Screws; Full Directions. other outstanding point of superiority of the Tropadyne circuit is that it Binding Post Strip; practically does not radiate, thereby not interfering with other nearby receiving stations. A saving of two tubes as well as an increase of selectivity We ship in 24 hours is obtained with this new circuit." RADIO SPECIALTY COMPANY, 100 PARK PLACE, NEW YORK 6.I.4 SEND NO MONEY Y. Tropadyne Gets Europe! SEE OUR RADIO SPECIALTY CO., 166 Park Place, New York, N. 2-PAGE 2BD, Aberdeen, on November 25th. Results Please send at once one complete Tropadyne Superadio Outfit "Received AD ON pay postman or good, except noises. 11:30 to 11:40 talk, from 11:40 to as advertised in April "Radio News." I will poor. Used PAGES expressman $60.50 upon arrival. 12:00 piano number. Piano number good, talk 1842 and Tropadyne Circuit." 1843 NAME J. RADIO J. ZIMMER, 157 James St., Newark, N. NEWS STREET or R.F.D. been verified by "RADIO NEWS" The above has CITY STATE

www.americanradiohistory.com 1'4' Science and Invention for April, 1925

1,1,,.,,,,,,,,,11,m11MITMIT11/17171V,,,,,,,MITTM111°,,,IMM,I,.IMM;,m_ MostWonderful The L'fivIlng DeaHl (Continued froh page 1240) Musical Instrument At first Frontenac liad planned to take tailed account of all that had happened there a larger party than this. in the Gardens of Paradise and had ended Invented Play "Would need more men-many rifles." with a few hints relative to the grisly possi- in a Such were the words of Wilkie, written bilities that awaited us. This, however, had even as his doom was coming upon him. If not produced the faintest sign of the most Minute he could only have set down what that thing fleeting hesitation. His words, on the con- No Lessons - was which he saw! trary, only made those brave fellows more No Practice Much deliberation had we had upon the than ever anxious to go. matter -Frontenac, Nunatak and myself - Of Sleeping Beauty he had not uttered a Greatest musical and the result had been Frontenac's decision single sensation of the age! syllable. (which Nunatak and I, all things considered, There were six sleds; in other words, each Never before any- thought a wise one) thing like it. Every- that the southern party man (except Frontenac) had his sled and should be small. team of dogs. Each sled-and load, that body simply wild As is is- about this usual in such cases, however, there weighed about 900 pounds. There were 90 was much to be said on both sides. The dogs, 15 in each team. And on one of those Play 20th Century element of doubt and uncertainty would rear sleds we would bring back a stranger load Your Way Wonder its head no matter which decision was than any vehicle made by man had ever No more high reached. When it came to the march itself, carried -Sleeping Beauty in her coffin of ice. the advantages to cost, hard les- were, of course, altogether Coffin ! Why, each sled, even now, what Popularity sons and long on the side of the small party. But, when with the black provision cases, had an un- practice. At one thought of the Gardens of Paradise and pleasant semblance to a coffin. last a Musi- the horror that lurked there -well, matters As for instruments, the principal ones were cal Genius then assumed a very different aspect, indeed. the following: Four thermometers, three has invented Seven men 1 Captain Livingstone's band aneroids, three hypsometers, five chrono- a marvelous had consisted of five (including himself) meter- watches, two sextants, three artificial instrument and its fate had been that anyone one awful to contem- horizons and one cinematograph- camera. plate. We should have but two men more; That day we made 17 miles and had, I be- can play who but here entered a factor -and a very im- lieve, 17 dog fights. can hum a tune. I had never seen crea- portant one, too -that at first sight, if the tures so surcharged with life as those ani- This instru- eye were kept on numbers alone, might be mals were. ment is overlooked. Forewarned is forearmed. And "As full of pep," quoth Numatak, "as The Marvelous we had been forewarned. We did not, 'tis ninety sticks of dynamite." true, know what that horror was there in And his remark, forsooth, was a most the palm- trees, but we knew that that horror apposite one. was there, and we would be on the lookout "But it won't last," the musher added, for it and prepared to meet it when it came; somewhat ruefully. "It'll be taken out TRADE SlideMARK. of whereas Captain Livingstone and his men them, and then we'll wisht that they was had never dreamed of the existence of that peppy once more." Trumpet -Sax monster with the enormous claw or of any- Swiftly now day followed day, and stead- A big, full -sized musical in- thing like it. strument made of solid brass, ily we moved on, deeper and deeper into polished and finished like the "That knowledge alone," said Darwin this terrible region. Though Ì say steadily, very finest Saxophone. You Frontenac, "doubles our band. Seven men I would nett don't need to know the first be understood as meaning that thing about music. You don't who know that there is danger and are pre- there was no interruption whatever in pared our have to practice, not a minute. to receive it when it comes are equal progress. Once, in fact, we were held camp - to at least fourteen who are walking right bound for two days by a blizzard. Other de- . You Can into a trap, so to speak, Though there will lays were met with, too, though slight ones. Play It be only seven of us, we will, as compared In no instance besides the one just mentioned rust HUM a tune in it with poor Livingstone's party, number four- did we lose so much as a single day, which, that's all. And, oh how trie teen men." all music rolls out -sweet and things considered,. was really a remark- mellow like the dreamySaxo- "That is very true," Nunatak nodded. able run of luck. phone or loud and clear "And I was just thinkin' what a wonderful Our camp at the end of the like trombone or trumpet. savin' march on This seems too good to be there'll be thataway in grub." the 11th of October was, by dead reckoning true. But it istrue- anyman, woman, boy, "In grub ?" (the sky had been overcast for 48 hours) girl, can play immediately. No lessons, no "In grub," quoth Louis Louisiana, "though exactly on practice -just hum your favorite the parallel of latitude 84 °. We tune. we'll number fourteen men, and maybe more, 'were now at the southern We will send you edge of that great there'll only be seven tummies to feed." plain of which Captain Livingstone had Absolutely FREE "Quite so," Frontenac nodded. "And each spoken and were about to FREE a phonograph record enter the moun- of us will be well armed, of a beautiful solo played on Mussehl's Slide- which was not tains again. Strange thoughts and feelings Trumpet-Sax. You will simply be amazed at the the case with the others." came to me as I stood and gazed away into sweet, mellow music produced by this wonderful "Only seven of us," Nunatak interposed. those tumbled masses before us. Accord- instrument that sounds like a saxophone. "Too bad the With the free record we will send you our other seven of us can't tote ing to Captain Livingstone, Sleeping Beauty amazing LOW Price Introductory Offer ,_a price shootin'-contraptions." lay in latitude 84° 25' other words, so low that -in she anyone can easily afford it. `Remem- "Each man," Frontenac went on, "will was distant now only 25 geographical miles. ber -you can play immediately with marvelous llave Sweetness-any tune you can hum. a rifle and two revolvers. And it is I suppose that Frontenac must have known Send for FREE Phonograph upon those revolvers, I fancy, that we shall what I thought and felt, for he came and depend when moving through the gloom of stood beside me and, after a few moments, Record Today -SURE the trees. The revolver, of course, is a bet- during which he, too, gazed away to the MUSSEHL St WESTPHAL ter weapon at close quarters than the rifle. southward, he said: 522 Water St., Ft. Atkinson, Wis. That thing with the claw, you'll remember, "A good day's march would take us to Bond, MUSSEHL CI WESTPHAL, dropped so suddenly upon them that her, Bond." 522 Water St., Ft. Atkinson, Wis. they couldn't fire even one single shot with "That's what I was thinking. I have my Gentlemen -Send me the Phonograph Record of the rifle." doubts, Solo played on Mussehl's Slide-Trumpet -Sax and your though, that tomorrow's march will Low Price Introductory Offer. It is understood that I remember that. And perhaps it would be 25 miles." this request places me under no obligation of any kind. have been the same thing had the weapon "I have mine, Please print or write very plainly. too. But it won't be long been a revolver." now before we see her." "Not if each man had had such a weapon." "Good God," I exclaimed, "what Name a hor- "You know," I said, "one of the strangest rible place to lie in from century to century, things about that horrible business is why from age to age and age again !" Address not one of them could get in a single shot." "Yes," said D_ arwin Frontenac; "a Irible "I wish," Darwin Frontenac answered, one, truly." "that that was the only strange L...... a...o ...... a.. thing And I thought that, as he stood there about it." gazing at that frozen, terrible waste of snow He had given the men a careful and de- (Continued on page 1246)

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www.americanradiohistory.com 1244 Science and Invention for .l Aril, 1925

Edited by Don't Lose Your Rights Before disclosing your invention to any- A. Po Peck one trend for blank form "Evidence of Conception" to be signed and witnessed. In this Department we publish such matter as is of interest to inventors and particularly to those A sample form together with printed in- who are in doubt as structions will show you just how to work to certain patent phases. Regular inquiries addressed to "Patent Advice" cannot be answered up your evidence and establish your rights by mail free of charge. Such inquiries are published here for the benefit of all readers. before filing application for patent. As If the idea is thought to be of importance, we make it a rule not to divulge all details, in order to pro- registered patent attorneys we represent tect the inventor as far as it is possible to do so. hundreds of inventors all over the U. S. Should advice be desired by mail and Canada in the advancement of inven- a nominal charge of $1.00 is made for each question. Sketcnes tions. Our schedule of fees and descriptions must be clear and explicit. Only one side of sheet should will be found NOTE: -Before be written on. reasonable. The form "Evidence of Con- mailing your letter tothis department, see to it that your name and address are upon ception" sample, instructions the letter and relating to envelope as well. Many letters are returned to us because either the name of the inquirer obtaining of patent and schedule of fees or his address is incorrectly given. sent upon request. Ask for them, -a post card will do. MUFFLER prosecute your idea at all. It is extremely old (880) Howard and very- inefficient. It is entirely too compli- ILANCA5IER W. Richards, Toledo, Ohio, cated a ALLWINE has conceived a new type of muffler for use in for use on automobiles because of the mul- connection with internal combustion engines, tiplicity of switches or buttons. The only feature said in it that is of Registered Patent Attorneys in U.S. and Canada muffler designed to combine oxygen with the car- any value at all is the stop -light bon monoxide actuated by the foot brake, but this in it- 255 Ouray Bldg., Washington, D. C. of the exhaust, producing carbon device dioxide, a gas not injurious to human beings. self is completely covered by patents. We would 'Originators of form Evidence of He advise Conception" wants to know whether or not the device is prac- you to entirely abandon your idea. tical. A. 1. Your proposed device for mixing oxygen with carbon monoxide will not operate in the COLLAPSIBLE SAWHORSE way you mention, because of the fact that car- (882) H. Nixon, Los Angeles, Calif., submits bon monoxide and oxygen will not combine to a design of a folding sawhorse, and asks our opin- form carbon dioxide, except in the presence of ion on the patentability of the same. extreme heat, or an open flame. The heat of the A. 1. There is no doubt engine but that the sawhorse exhaust is by no means sufficient to bring you have designed is patentable, and it seems to about this union. present marketing possibilities. It is absolutely- necessary that the device be rigid MIXING and quite sta- VALVE EXHAUST tionary. We would advise that you have a search TO THE MAN WITH made on this idea. AN IDEA I offer a comprehensive, ex- INTERNAL COMBUSTION ENGINE perienced, efficient service for (883) H. E. Fisher, Montreal, P. Q., Can- his prompt, legal ada, submits a design for a new type of internal protection and combustion engine which is supposed to make the development of his proposi- TO ENGINE B FFLE PLATES the entire unit operate at a higher temperature tion. The above illustrated muffler will not mix oxy- than the present day type of engine, the excess Send sketch? or model and descrip- heat being made to perform further work. We tion, for advice gen with carbon monoxide, thereby evolving wish to advise Mr. Fisher as to cost, search a harmless herewith that our per- through prior United States patents, gas, carbon dioxide. sonal answer to him was returned because of the etc. Preliminary advice gladly fur- fact that the address he gave us in his first nished without charge. communication was not the correct one. There- My experience and familiarity with AUTOMOBILE SIGNAL fore, we are using these columns to convey our various arts frequently enable me to opinion to him. accurately advise clients as to prob- (881) Joseph H. Furey, Berniser, Pa., sub- A. mits a design of I. Devices of the nature you mention have able patentability before they go to a system of automobile signal been tried in many any expense. lights upon which he asks our advice. The cir- different ways, but have never been successful. The same would be found with Booklet of valuable information cuit of the system is given in these columns. yours. and form for properly disclosing A. 1. We would not advise you to attempt to In your idea, free on request. Write the first place, the most efficient operating tod;.y. temperature for a gasoline engine is about 178° F. At this temperature the gasoline mixture explodes RICHARD B. OWEN, Patent Lawyer RIGHT with the greatest force, and the greatest 164 amount Owen Building, Washington, D. C. D- SWITCH ON BRAKE RED LIGHT of air can be mixed with the gasoline. When 41 V Woolworth Bldg., the temperature New York City BACK 1 of an engine goes above this figure, HEAD the efficiency of the engine is lowered, STRAIGHT , and furthermore, lubrication is not satisfactorily LIGHT t, , carried out. I. STOPS We do not believe that any device of the nature you suggest would add to the efficiency C. L. PARKER of the engine, but would in fact detract from Ex- Member Examining Corps. U. S. Patent Office the same. Attorney -at -Law and D- N Solicitor of Patents LEFT - LEFT LOCK NUT American and Foreign Patents secured. Searches made (884) J. E. to determine patentability. validity and I Styert, Detroit, Mich., asks our infringement. opinion on the complicated lock nut which he has Pamphlet of Instructions sent upon request There designed, McGILL BUILDING are entirely too many switches on the and which we are illustrating herewith. WASHINGTON, D. C. above illustrated automobile traffic signal. A. 1. Referring to your lock nut, we would advise that the system is entirely too complicated for exploitation and would certainly not advise you to attempt to secure a patent upon the same, because we doubt that it could ever be made PROTECT popular. INVENTORS YOUR IDEAS BUSHING

Send for our Guide Book, HOW TO GET A PATENT, and Evidence of In- SPRING vention Blank, sent Free on request. Tells our terms, methods, etc. Send as - . - - . i model or sketch and description of your invention for instructions. No Name charge for the above information. Street RANDOLPH City & CO. Dept. 172, WASHINGTON, D. C. The lock nut illustrated above is far oo corn - plicated to ever merit a wide sale.

www.americanradiohistory.com Science and Invention for April, 1925 12.15 DATE s PROTECT YOUR IDEAS FREE ANY NEW article, machine, design or improvement thereof, or any combination 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.

Drafting and Specification Room of Clarence A. O'Brien Registered Patent Lawyer, Washington, D. C. ALL COMMUNICATIONS are held in strict confidence. My personal, careful and thorough attention is given to each case. I offer you efficient, reliable and prompt service -based upon practical experience. Highest references. NO CHARGE FOR ABOVE INFORMATION. These books free WRITE TODAY FOR FREE BOOKS, "HOW TO OBTAIN A PATENT" and "INVENTION AND INDUSTRY" and blank form "RECORD OF INVENTION." These books will give you valuable information, and they may save you much time and effort. Send for them, NOW. My practice is devoted exclusively to United States and Foreign Patents and Trade Marks. Write me freely, frankly and with full confidence ; it is very probable that I can help you. 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 receiving your idea I shall write you as to procedure and costs. CLARENCE A. O'BRIEN REGISTERED PATENT LAWYER Member of (COURT OF APPEALS, DISTRICT OF COLUMBIA, UNITED STATES COURT OF CLAIMS; Bar of (SUPREME COURT OF UNITED STATES, SUPREME COURT, DISTRICT OF COLUMBIA Practice Confined to Patents, Trade Marks and Copyrights FREE COUPON CLARENCE A. O'BRIEN, Registered Patent Lawyer 5391 Security Savings and Commercial Bank Building Directly Across Street from Patent Office WASHINGTON, D. C. Please send me your free books, "HOW TO OBTAIN A PATENT" and "INVENTION AND INDUSTRY" and blank form, "RECORD OF INVENTION," without any obligation on my part. Name Address IMPORTANT -WRITE OR PRINT NAME CLEARLY.

www.americanradiohistory.com 1246 Science and Invention for flAril, 1923 _m1.:17t111111::nn:::::11n:.::11:n:::::::1111t:n:::::1:n::::::1::1:,:,,,1,11,11111111111111111,,::,:,,::11::11111 The LIlvIlza :, Death Mason, Fenwick & Lawrence You too can now earn (Continued front page 1242) to $250 a Week $100 Trade Mark and Patent Lawyers I'll train you-in your spare 11111111111111i111 011 11,111,11111111111111111111.11111,1111111111111111111 Beá Master Washington, D. C. :: New York :: Salesman and rock, the poor girl, for the first time, Chicago I'll make you a Master Sales- became an object other than one of mere man. I guarantee it. Selling Established over 60 years. Write us. offers you amazing opportuni- scientific interest. And, when he spoke, I ties -4.000 to $15,00.) a year. saw my thought become a certitude. No other Rae offers so References: many National Confectioners' Association. Chi - jobs -such big money. "Poor little kid !" is cago; National Cannera' Association, Washington. You what he said. Life D. C.: Can Learn to Sell. Savers, Inc., Port Chester, N. Y.: Bon Ami. Co. Don't think you can't. I'll During the whole and U. S. Cigar Co., New York show you of the following day, late City: Hershey Choco- how-quickly and Co., Hershey, Pa.; Stephen F Whitman & Son, easily, My Selling Course, posi- the going was very difficult, but we suc- Philadelphia, Pa., and many tively beet others. money can buy. ceeded in making good 14 miles of southing. Book. Cup coupon now for the This FRE greatest book of your life - was according to dead reckoning, for Inventions protected. Trade marks registered. The Right Way to Sell ". we had not yet succeeded in getting a single "TheJMan WhorMakes Money -Makers glimpse of the sun. The next morning, JAS. P. WARD, General Sales Manager, however, he broke through the dark curtain Manufacturers Sales Corporation of America. 5054 Administration Bldg., and soon was scattering the clouds in all 1774 -1790 Montrose Ave., Chicago, H1. directions. A meridian Dear Sir: Send me at once your altitude gave our "The Right Way Free Book - latitude PATENTS to Sell." as 84° 21'. By dead reckoning, it Name TRADE Add ress was 84° 17', which speaks well indeed for MARKS DESIGNS Occupation the accuracy of our sled- FOREIGN PATENTS meters. .A Only four miles now. from Sleeping Beauty. MUNNNN & CO. And by two o'clock we had reached the PATENT ATTORNEYS 1000 NEEDED spot. Antedated ilote 7846 with the Scientific American Keen and eager were the looks which 6t8 Woolworth Building, New York City INVENTIONS! 325 Scientific Frontenac American Bldg., Washington, Here is the most remarkable and I sent as we opened that D. book ever offered to in- 414 Tower Building, Chicago, 111, ventors. One Thousand needed inventions listed and gorge in the mountains. The others, wholly Hobart described. Arranged as follows: General Problems; unconscious of the interest that was attached 2227Van Nuyss Building, jLosAngekr, Cal. Automotive; Mechanical; Electrical; Chemical; to this place. Book and Radio; Marine. Separate c,mtinued steadily on, the Information on Patents and TradeMarks chapter on the Ten Most negotiation by Request. Needed Inventions. This book may give you one idea of the difficult route engrossing that can win you à fortune. Nothing else like it has their attention. ever been published. Compiled at enormous expense. Edited by Raymond Frontenac and I halted. Francis Yates, formerly Man- LAST CALL TO INVENTORS! aging Editor of a leading scientific magazine. Over "There it is, Bond!" said he, pointing, then 100 pages, durably bound. Send no money. Pay post- File your application now for the man only $1.00 plus raising the binoculars to his eyes. "There's postage on arrival. Money back the after 10 days' examination if desired. Limited edi- cavern mouth, though pretty well filled, tion. Write NOW. it appears, with snow." EXPOSITION Of INVENTIONS BUREAU OF INVENTIVE SCIENCE For some time we stood there looking and Management of DEPT. 74 ROCHESTER, NEW YORK wondering, then pushed on after the others. THE AMERICAN INSTITUTE A OF THE CITY OF NEW YORK half mile or so beyond the place, a level 47 West 34th St., New York spot, comparatively speaking, was reached, MAKE MONEY when we halted and made camp -a proceeding, it was patent, AT HOME that puzzled the others. Have your invention patented Frontenac, however, offered not a single INVENTORS Completem information In mr syllable of booklet 'Patents." Cnpy free. VCR; can earn good money at home in your spare explanation. time making show cards for us. No canvassing Straightway he, Nunatak and myself or soliciting. We show you how by our new slam headed AMBROSE T. BUCKLEY nstructograph method. We supply both men and for the cavern, the musher carrying women with work at home no matter where you 1., . a spade. It was plain that that spade in- Patent and pay you cash for all wort: completed each week. Attorney Full particulars and booklet free. Write today. trigued Nunatak, but not a word of explanation was vouchsafed him, 150 Nassau St. New York City AMERICAN SHOW CARD SYSTEM, LTD whilst he did not 110 Adams Building Toronto, Canada suffer curiosity to elicit from him the slightest query. As we were drawing near, he suddenly stopped and stood, peering up. "Looks mighty like a PATENTS ®F'REE7INVENTORS cave up there," he if your observed. BOOKLET FREE HIGHEST REFERENCES invention is new and useful it is patent- PROMPTNESS ASSURED BEST RESULTS able -send me your sketch. Inventions deve'- "That's what it is," Frontenac told him, Send drawing or model for examination hed, patented. Trade marks and copyrights ob- and report as to patentability :ained in the U. "probably the most wonderful cavern in all S. and Foreign countries. the world." WATSON E. COLEMAN, Patent Lawyer Z. H. POLACHEK 644 G Street, N. W., Washington, D. C. Reg. Patent Attorney Nunatak made no response. ®Professional Engineer The next moment we had started up. 70 Wall Street New )(ark 11111 Frontenac was the first to reach the entrance; a few seconds, though, and I was DON'T beside him. INVENTORS! WEAR "Not a sign of her, Bond," he said, in a Our facilities low to assist you in securing patents, A TRUSS voice. models, capital, etc., and our complete service "It's the snow -the snow!" I exclaimed to members will interest you. Dept. A. BE COMFORTABLE - excitedly. INVENTORS INTERNATIONAL INSTITUTE Wear the Brooks Appliance. the mod- "Of course." 15 Park Row, New York ern scientific invention which gives rupture sufferers immediate relief. It He turned his head and looked down. has no obnoxious springs or pads. Au- tomatic Air Cushions bind and draw "The spade, Nunatak," he said. "Hurry together the broken parts. No salves up with that spade !" or plasters. Durable. Cheap. Sent on trial to prove its worth. Beware Mr. C. E. Brooks "Ain't I hurryin' ?" came the aggrieved As of imitations. Look for trade -mark bearing portrait and answer of the musher. "Do you Ont firms in Amenos we , Iguature of C. R. Brooks which appears on every Appli- think, boss, give inventors at lowest ance. None other genuine. Full information and booklet that I'm a spider? PATENTS consistent charge, a sont free in plain, sealed envelope. service noted for rossais, evidenced by many well known I lister to think," he went on, "that I Patents of extraordinary value. flesh, Patent- Sense,free, BROOKS APPLIANCE CO., 172A State St.,Marshall. Mich. Lacey& Lacey, 644 F St.. Wash., D.C. Estab.1869. was a musher ; but the way you fellows sailed up this here place showed me that I was a turtle. If it hadn't been for these STÚDYAT HOM E crampons, I'd sure enough have broke my Directe y neck." VCLASSRINGS &PINS o Largest Catalog Issued -FREE irbe 7iníbertsitp of Cfjícago Frontenac and I had started to scoop off p lPs Courses in English, History, Chemistry, Business, the snow with our mittened hands. cSearam Pricesri s 8 Mathematics, Education. Psychology, and .35 other A few subjects command moments, for c.aeto tyy, e0 credit toward a Bachelor degree. though, and Nunatak was nearing em blearsm large or Begin any time. Address 27 Ellis Hall, University of too smal. Species Chicago, Chicago, Ill. the top. I reached down for the spade; as designs made on request. (Continued on page 1248) METAL ARTS CO., IiL 7723 lutA Aye., Rochesbr, N.Y.

www.americanradiohistory.com 1247 Science c.nd Invention for d pril, 1925

I TRADE-MARKS

AND'> CCiPY'RIGHTS' , ,' 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 invention for INSTRUCTIONS. NO CHARGE FOR THE ABOVE INFORMATION Our Four Books Mailed Free to Inventors Our Illustrated Guide Book CFitap, NI.. Office HOW TO OBTAIN A PATENT Suite :111I T acc ma E idg. Full instructions regarding U. S. Patents. Our Methods, Terms, and too Mechanical Movements illustrated and described. ¡"/ OUR TRADE MARK BOOK «./ necessity of Trade Mark Shows value and w i Protection. Information regarding Trade e competition in trade. 11 '. iIarks and unfair -ï e, New York Office 'E . i , . v4 Suite 1007 Woolworth Bldg. OUR FOREIGN BOOK in Foreign it ;l, We have Direct Agencies ¡ 1, I 1 . Countries, and secure Foreign Patents in Ig' I shortest time and at lowest cost. la, . . á ; r ..,. ._ ií 1 l ' 1 Progress of Invention I Pressing Problems by '-°"I t ; Description of World's Most I Leading Scientists and Inventors T itiji F. ._ .-.- .. ..:...... ALL COMMUNICATIONS AND DATA STRICTLY CONFIDENTIAL -' INTERFERENCE AND INFRINGEMENT SUITS PROSECUTED Pittsburgh, Pa., Office Suite 514, Empire Bldg.

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I, VICTOR J. EVANS & CO., Patent Attorneys Main Offices: 779 -9th Street, N. W., Washington, D; C. j I Gentlemen: Please send me FREE OF CHARGE your LlFREE G books as described above. COUPON Naine San Francisco, Cal., Office 1010 Hobart Bldg. Address Suüte

www.americanradiohistory.com 1248 Science and Invention for ,9pri1, 1925

,11 1111 1, III The Lgvi> Death A 1925 (Continued from page New Socket i 1246) that means Better Reception! I straightened up, it was seized by Fronte- nac, who began to remove the snow with J Edition feverish haste, careful, though, not to dig into the ice. ti P At this Nunatak could no longer restrain his curiosity- which, indeed, had suddenly "20 Radio become something very like astonishment. "What," he exclaimed, "are you lookin' Hookups" for ?" Scarcely had the last word left the mush - er's lips when an exclamation broke from Each Hookup Darwin Frontenac. I bent forward to see, my heart beating After exhaustive research, our engineers heavily. have developed VIRALON, a special glass. Given in Two processed for 100% efficiency. Sturdy and Frontenac dropped the spade and began rugged, absolutely heat and moisture proof, to dust the snow from and unaffected by those influences that com- Ways the ice with his mitts. monly make rubber, - Pers- Suddenly he paused -exclaimed rubber derivatives, por- again celain or vitreous pointed. - products so inefficient. Other esclusive features are Ezyklean Contacts pective and "Look!" he (proof against corrosion)-One-Piece cried. "Look, Bond ! There Contact Springs -Handy Soldering Terminals, etc. Price Schematic she is!" $1.35 standard size. CHAPTER XXIII Write for interesting pamphlet If your dealer cannot supply you send us $1.25 THE SUDDEN VOICE and parcel post to cover each socket. Twenty of the finest, I had already seen her DURAY RADIO CORPORATION -or, rather, her Dept. most up -to -date hookups head and shoulders, for that was all of the 18, 261 Washington Ave. Newark, N. J. sleeper that, as yet, was visible. on the best receivers. A Frontenac dropped to his knees, put his gold mine of Radio cir- head close to the ice -front and peered in at the girl's face. cuit diagrams. Nunatak thrust himself forward to see, his swift movement threatening for a mo- oURAY All given in the latest ment to destroy my equilibrium and precipi- tate me off the spot. ALL-GLASS vi RALO N Consrad style which The next instant an exclamation of wonder and horror burst from his lips. shows not only a perspec- SOCKET "What awful thing is this ?" the musher tive view of the complete cried. To that neither of us made any response. set, but also a complete Darwin Frontenac raised his head and schematic circuit diagram turned his look up to me. "Her eyes," he said. "Look at her eyes, of each circuit. Bond." I bent forward and looked-looked straight play into the your eyes of Pattern contains the sleeper. They were 20 no more than eight inches from the edge of the ice. They blue -prints size 9 by 12 were wide open ; the long way dark lashes were as natural as though it were ahead inches together with a 4- air and not this paleocrystic ice that incased page them, and the pupils were extraordinarily LADING profession- instruction folder dilated. The als, like Carroll Mar- iris seemed blue, but whether tin, famous trombonist that shows how to read that was the actual color or not, I could not of Isham Jones' Orches- tell. tra choose Conn instru- each circuit and also a "It is horrible!" I said, shuddering. "Hor- ments because of Conn rible !" supremacy in tone, tune, complete chart of Radio mechanism and easy playa "It is wonderful, Bond !" said Darwin - ing qualities. You'll get symbols. Pattern is size Frontenac, bending forward once more. "It ahead faster with a Conn, is wonderful!" socially or professionally 9% by 1272 inches and is "I'd say," -win new friends, make came the voice of Nunatak, "that big money if you choose. McQuestion is right ; 'tis an awful printed in handsome sight Carroll Martin to see. And 'tis a mystery, too ; how on colors. earth did this poor creature get here ?" "She," I told him, "has been here always." Cultivate Vour uciead `lump "Always ?" Conn is the only maker of every instrument for Price "Ever," I explained, "since the snow and band; saxophones, trombones, comets, etc. Write ice fell upon the Antarctic." now for Free Book "Success in Music and How to Win It," by Sousa and other artists, and dc-silo He stared at me for some moments. of Free Trial offer. Mention instrument. "What you talkin' about, McQuestion ?" C.G.Conn,Ltd., 456 ConnBldg.,Elkhart,Ind. 50Cc he exclaimed. "I know what I am talking about. Look at her dress ; ON SALE AT it is almost tropical. She has ALL been here for thousands upon thousands of OK1 RADIO AND years. No man living can say how long MINSTUEENTSBAD this poor girl has been lying here-here in , uR`- NEWS DEALERS her coffin of ice." "Coffin !" The next instant Published by _Nunatak's hand had closed on my arm with convulsive strength. Amateur Mechanics -Model WADE Makers -Students BENCH -LATHE "A coffin !" he cried. "McQuestion, tell Cap: 1" dia. a 12" me this: Do you length. Silderest has think that she is like them travel entire length of poor dogs was before he woke them ?" led. Leadscrew inside The Consrad Co. ! Jed. Hollow spindle. I nodded. Turning. facing, bor- ing, drilling, wind I 233 Fulton Street "The probability," I told him, "points in - that direction." Price $28 F. O. B. New York.ng Freee Circulars. THE GEROLD COMPANY New York, N. Y. (Continued on page Dent. 1250) S -8, 120 Liberty Street New York

www.americanradiohistory.com Science and invention for April, 1925 1249 RAGEMCO Radio Headquarters for the Finest and BEST Radio Tools RADIO RADIO TOOLSET HANDI- This is the handiest TOOL fr : set of tools ever made : for Radio Work by Bends Bus Bar or ® and filmo=a the makers of the wire strips famous "YANKEE" scrapes wire, Tools. It contains the bores and reams following: 1 Rochet holes, etc. Tool Screw -driver, 6174 in. consists of 4 in. attachments; 1 Blade, 5% x 3 -16; I black japanned hand e, to which is attached wire bending long holding all sided Blade, 31/4 x t/a; 1 Blade 21/4 x 1/o ; 1 Countersink; 2 Sock- device, with nickeled ferrule and 3 in. long two et Wrenches for all small nuts; 1 Reamer to enlarge hole - reamer. 5Cc in panel from Va x %; 1 Wrench, one end 5 -16" square PRICE -No. 702 or hex. for jack, other 1/4" hex.. etc. PRICE per set -No. 701 $3.00 TOOL CHEST Set consists of "I.00K- HAND DRILL GRIPb master ha n- T h e liardwo,c1 long, black a fin- handle is hollow ish with steel chuck, nickel to store drills. plated, buffed and with the following 9 tools: Saw, brad- Iron frame, nick- awl. large screwdriver, file, scratch awl, gimlet, reamer, eled parts, ball T hisel. small screwdriver. Each tool of fine steel, drop hearing three jawed chuck holding and centering accu- [urged tempered, hardened, and nicely finished. Set comes rately round shank drills from 0 to 3 -16. Length of in Ieatheroid box with tray. drill. 12 inches. PRICE -No. 703 $1.85 The Simplest Practical PRICE -No. 303 $2 25 Radio Set Made SCREW STARTER WIRE BENDING DRIVER TOOL and Holds any screw by its slot For making eyes, loops. with a firm grip. makes it easy 52.50 and offsets on Bus to place and start screws in difficult places. bends, j. Bar wire. With this desire Just the tool for the Radio Constructor. All A complete Radio Receiver Constructor ran parts heavily nickeled and polished. wire his set to compare fav- PRICE -No. 304 51.00 including Radiosem. Phone orably with any factory made set. Easier to use and more accurate than pliers. Full directions in box. Made of and Aerial heavy steel, blued and finished. PRICE -No. 203 $1.00 11.l1Cfllili RADIO The Complete Outfit Consists !M DRILL SET CI=-W E,c tll Ti II' Is- T of Three Parts CIRCLE CUTTER Composed of 10 straight shank Especially designed for the Radio twist drills, fitting all hand (One) Constructor. Made of the finest VVVVVifITT and breast drills. The selec- material and equipped with the tion of these drills has been highest grade high steel cutting especially made for Rad o Constructors and consists of The RAD(OGEM bits. It does three things at once. the following sizes: 1 -16, 5 -64, 3 -32, 7 -64, 1/4, 9 -64. The simplest radio outfit made -yet as It drills its own pilot, cuts out 5 -32, 11 -84, 3 -16, 17 -64. Drills are mounted on white A plug and puts bead or scroll Holland Linen with sizes clearly marked. practical as the most expensive. crystal around the hole in one operation. PRICE -N o. 305 $1.25 receiving set that you can operate and Cuts holes % to 4 in. in diem enjoy even though you know absolutely PRICE -No. 402 $3.00 nothing about radio. You receive the 401. Same tool but smaller and not fitted with bead or scroll in RADIOGEM unassembled, together with one operation. a clearly written instruction book, which PRICE -No. 401 $2.00 shows you how to quickly and easily con- -_. 1 - _ struct the set, using only your hands and - a scissors. The outfit comprises all the necessary wire, contact points, detector ELECTRIC SOLDERING IRON mineral, tube on which to wind the coil, \\0 c A perfect tool for Radio Work. Operates either on 110 - etc., etc. The instruction book explains 611\ {_ eTlt A.C. or D.C. The heat element is of Nichrome, simply and completely the principles of rEL which prevents overheating and assures the desired even radio and its graphic illustrations make temperature. Size of Iron. 101/4 in. long. A 4 -ft. cord the assembling of the RADIOGEM real nd plug is furnished. fun. PRICE-No. 800 $2.00 Especially designed for Radio Work by the makers of the (Two) famous "Yankee" Tools, A beautiful balanced, small. Powerful drill with 4 to 1 ratio of gears for speed. Spe- cial chuck 9 -32" capacity, to take largest drill, most.ty The GEMPHONE furnished with drill or tool seta. Length over all 9% in An adjustable, 1,000 -ohm phone com- Weight t'e lbs. PRICE -No. 302 $2.75 plete with 3 -ft. cord -the first inexpensive adjustable receiver made. The Gemphone is of standard type and made of the very best grade of materials throughout. The case is made of turned wood, an exclusive feature with the "GEMPHONE." This is responsible for its exceptionally rich, and mellow tone. Like RADIOGEM, the GEMPHONE is sold unassembled: Our Three- in -00e Nut Wrench. Consists of handle with hol- \awiac CUTUP,, pamphlet shows how to as- low stem 6 inches in length and three interchangeable Combination PI'er, W ire Cutter. W ire Former and Wrench. Instruction sockets fitting sizes of nuts. The hexagon sockets semble it in two minutes, using only a popular Drop forged, sien Ier but exceptionally strong. r; in, b ng. grip the nut solidly. PRICE -No. 2C2 75c screw driver. PRICE per set -No. 301 05c (Three) The AERIAL OUTFIT Consisting of 100 ft. of standard copper aerial wire and two porcelain insulators. Long Sharp Nose, Side Cutting Pliers. Just the pliers Side Cutting Nipper. Lap Joint. For cutting all kinds of for the radio Constructor. Bends and cuts all kinds of Complete Radiogem wire. Jane hardened and oil tempered. Natural steel soft wire. Nose 11/4 inches long, black body, polished finish with polished jaws. Length 6 inches. jaws. T.ength 51/4 inches. Outfits - $2.50 PRICE-Na. 201 75c PRICE-No. 200 75e The Radiogem, only - 1.00 Order all tools by order number. All goods are shipped free of transportation charges to all parts of The Gemphone, only - 1.00 the United States and possessions the same day as the order is received. Aerial Outfit, only - .50 MONEY REFUND GUARANTEE If you are not satisfied money will be refunded on return of goods. \The RAD(OGEM CORP., 66-S W. Broadway, New York/

www.americanradiohistory.com 1250 Science and Invention for April, 1925

The L}lvlil3t.l,, DefterD One Radio Book (Continued from page 1248) Everyone Reads

He turned his - look to Darwin Frontenac, who had arisen and was Once more-remov- ing snow, so as to obtain a., view - of the

sleeper's whole person. - - -- "And,'' thë' mu Sher said, ."you are ,goin' tö wake her up,-bcss -wake' her up just like

you did them poor dogs ?" _ - Frontenac paused, and for a moment. or two looked at the other with a curious, ab- o stracted expression on.. his lean face. "Such. Louis, is my hope." he said. "Yes, The Radio Broadcast I am going to awake her."

"But " - Listener's Book of "Well ?" Information and Log "Even you, boss, can't waken dead people. This purty darlin', her heart is still and Record is not only frozen ; the poor girl is dead." a complete, practical book s of those essential Radio facts that "She may be, Louis, and she may not everyone who owns a radio should be. No one can tell that- now." know, but it is also a handy log record for those who want to keep a s "I can, boss." w, .s, , e record of the stations they receive. er s, "A man," Darwin Frontenac added, "can The book is enclosed -r e,>z.,s in a handsome E a :-¢ wro,. only balance probabilities and base his be- two -color cover, bound in Loose -leaf tr. r r +" ¢ `p,,,,. lief on the result. That is what I have fashion, so that new pages can be .._ done, inserted if necessary. It contains 80 SILENT and my belief is that the girl, though pages, each one containing informa- entombed in this mass of solid ice, is not tion more valuable than the last. MODEL a corpse." The following is a brief summary of - the information contained in this Noe "She's dead !" said Louis Louisiana. "You book: 8 awoke 1orTIus them huskies, but you'll never awake Information for the Broadcast Listener: this sleeper, boss." Vacuum Tube Table: Meter wave lengths: AMA Radio Batteries: Wireless code chart: "That," Frontenac answered, a wan smile Station log chart: 0 passing athwart his Complete list of Broadcast Stations of the features, "is just what United States, giving Power. wave length. you said about those dogs, because they lay and Time of Operation each day of the week. there stiff and frozen." Log Sheets for tabulating the dial settings Bargain of the stations you receive on your radio. of Book, in. by will send you this wonderful typewriter with abso "I guess you're right, boss," said Louis Size 6 9 ins. with handsome wElutely no obligation to you whatsoever. You send no Louisiana. 2 -color cover. money. When the machine arrives, you deposit only $3 with your express agent and test this remarkable bargain thor- He turned slowly and sank down upon oughly in your own home or office for 10 days. If you are PRICE not satisfied it is the greatest value and the finest type- the ice at Sleeping Beauty's feet. writer you ever saw, just tell the expresa agent and he will "Great Lord," he said, hand back every cent to you. If you keep it. you send "what will it be Postage Paid monthly payments so small you'll never miss them -just next ?" like rent. LIFETIME CHANCE! Soon Frontenac had finished. He stood Our New Special prices are the lowest ever made on the there leaning on his spade and looking 504 world famous, BALL- BEARING Silent L. C. Smith -late down style models -up -to -date, full size perfect machines - on the sleeper. Published by every modern convenience -absolutely finest quality rebuilt THE E. I. COMPANY and guaranteed for 6 years. No other typewriter at any- "What you goin' to do ?" queried the where near our price will give as many years of perfect musher. `.'goin' to cut ?" service. We are the largest exclusive dealers in L. C. The Consrad Company Smith Typewriters in the world. The easiest running He broke'off - Sole Distributors and, turning quickly around, and longest wearing typewriter ever built. Over half a million sold. Easiest to operate and learn. peered into the dark mouth of the cavern. 233 Fulton St. FREE TO YOU NOW! "What's the matter ?" I asked. New York, N. Y. Complete Course of Lessonson Touch Typewriting; Operating and Instruction Book: Tools and Waterproof Cover -all free "I thought that I heard somethin' -in with each machine. Send for Free Trial Plan; New Special there." Low Price Offer; and Booklet of Valuable Typewriter Information before offer is withdrawn. "What ?" SMITH TYPEWRITER SALES CORP. 303.360 E. Grand Ave. Chicago, lllinolS "I dunno what. It sounded like a voice."

. "A voice ?" said Darwin Frontenac. FREE TRIAL COUPON He laughed. Smith Typewriter Sales "Probably an echo of your own." 303-360 E. Grand Ave., Chicago, U. S. A. ònsrad Send me your New Special Offer; Free Booklet of Valuable "I suppose so," the musher said. "That "RADIO'S FOREMOST PUBLISHERS" Typewriting Information; Your Catalog; and Free Trial must have been what it was -that or just Plan with no obligation to me. plain imagination. Name "But, as I was about to say," he added, "are you goin' to cut out a block of this Address ice, a blòck with the girl inside of it, and take her up to the Multnomah?" "Just so. We'll disturb nothing here, though, until we come back from the Gar- TRUTH INFALLIBLE! dens of Paradise." ACCURATE and SCIENTIFIC "That's as I figgered it. You'll take her to the Multnomah, and then you'll awake True -Tone Haven't you been waiting and hoping that one her day you would gain that profound knowledge -if she ain't dead." BENNIE KRUEGER Saxophone which would give you the key to all your desires' "I'll awake her," said Frontenac, "when Director Bennie Haven't you longed for some strange Krueger and His Easiest of all instruments to power we get back to Seattle. There Orchestra Bruns- play and one of the most which would make you a master of things? are, of wick Recorda. beautiful. Three first lessons Haven't you often wished that you could sud- course, other reasons why I would never sent free give you a quick denly find yourself in an enchanted path, and awake easy start -in a few weeks this girl here in the Antarctic ; but you can be playing popular that you could there discover an Aladdin's most surely I tunes. No teacher neces- Lamp? would never do it unless there sary. You can take your was a woman at hand." place in a band ororchestra You can have all of this. in ninetydays, if you so desire. Inquire- "Of course," Nunatak nodded; "I was Most popular instrument for dance orchestras, home entertainments, unthoughtful there." church, lodge and school. A Saxo- Zbe /amp of RnoYvIebge Frontenac smiled wanly. phone player is always popular California socially and has many opportunities to La Jolla, "It wasn't the only point, Louis, on which earn money. Six Days' Trial and easy In Canada: 405 Metcalfe Avenue, Westmount, Quebec. you were unthoughtful." payments arranged. (1t5) Free Saxophone Book 111=neI He sent his look into the cavern. A few models and gives first lesson chart; also pictures of famoue Insure your copy reaching you each month. Sub- moments, and he turned to Nunatak and professionals and orchestras .Just send your name for a copy. scribe to SCIENCE & INVENTION -$2.50 a Mention anyother instrument in which you may beintereated. year. Experimenter Publishing Co., 53 Park Pl., said: BUESCHER BAND INSTRUMENT CO. Everything in Band and Orchestra Instrument: N. Y. C. "Louis, I wish you to return to camp and 719 BUESCHER BLOCK - ELKHART. INDIANA

www.americanradiohistory.com Science and Invention for April, 1 5,25 1251 get those two lanterns. You wondered, I believe, why we were taking along those lanterns." "I did, boss ; but I see now why you Go After the brought them." "And bring that twine, also, Louis. There are two miles of it on that spool." Big -pay Job! "Aye, aye, boss. Anything else ?" "Yes ; ask the others if they care to come "Know electricity as experts and see the sleeper -and the inside of this know it and get an expert's pay" cavern." Louis Louisiana sent a curious look into DON'T be satisfied to worry along in little low, jobs with little pay. Master the finer the dark entrance. points of electrical practice and bring the "Somethin' in there, boss ?" big pay job within your reach. Croft will show "Of course. God only k nows what. you how. Through his famous books he will There's a door in there." teach you electricity as experts know it and put you in line for an expert's pay. Forty "A door ! Goin' to open it, boss ?" thousand men are using these books to step Frontenac laughed. ahead -WHY NOT YOU? "According to the descriptions given by Captain Livingstone, we'd have to have drill A great book on transformer or dynamite to see what is beyond that practice free if you order now! door." "Then we ain't goin' to see what's behind it." of Practical Electricity "And," Frontenac added, "see that none The Croft Library of the dogs follow; fasten them up, every A Combined Home Study Course and Reference Library one of them." 8 volumes-3000 pages -2100 illustrations-flexible Keratol binding Was $27.00 -Now $19.50 "Great poodles, boss ! What's the idee ?" Darwin Frontenac moved a hand toward No method of teaching electricity offers AM tells ,.sou things you need to know FREE about motors, generators, a quicker. surer way to success than the armatures, com- the sleeper. Croft books. mutators. transformers, circuits, currents, saw her, they with the of switchboards, distribution systems -elec- " There's no telling. If they Starting right in with the ABC's trical machinery of every type, installation, might dig her out." modern electrical practice. Croft takes you operation and repair -wiring for light and through his books lu easy steps. Ho gives prover -how to do it mechanically perfect, "I was untoughtful again. 'Twouldn't be LIBRARY you the secrets of aicress in electricity In in accordance with the Na tonal plain words, figures and illustrations. Electrical puppy -play, that," said the musher ; "but Code -wiring of finished buildings- Under- Croft teaches you electrical practice com- writers' and municipal requirements -how they might do it all the same -dig her out Taylor's plete- inside and outside work -central to do a complete job, from estimating it, her bones, even though she is stations and the whole subject. He takes to completion -illumination in its every and strip you in quick, easy a ens from the simplest phase-the latest and most improved meth- froze like a rock." Transformer principles to the rmnplete and economical ods of lighting-tamps and lighting effects, "We'll take no chances, Louis." operation of a great central station. etc. "That all, boss ?" Practice The Sure Way to Bigger Pay "All, I believe," nodded Frontenac. The musher turned to descend. IF YOU ORDER Big salaries are paid in the electrical field for expert knowledge. The man who minute, I said. "I knows electricity in all its many phases -the man who has completely mastered the "Just a Nunatak," want subject trans A to R -ean picks his own job and name Isis own salary. The only way you to get a couple of photographs." NOW ! ran carts more is to learn more. Small knowledge means small pay. Learn the way to These taken, Louis Louisiana started forth- bigger pay. Become an expert. with for the camp. FREE TRIAL EASY PAYMENTS Frontenac lapsed into brooding silence. I The proof of all we have said is in the If you decide to take this sure road to moved up to the ice once more, dropped on hooks themselves. and it costs you Promotion. you need send only $1.50 in ten YOU SAVE N- O- T- H -I -N -G to examine them. There days and pay the balance at the rate of lovely, We pay $2.00 a month. You do not have to send my knees and gazed in upon that are no charges of any kind to pay. any money to see the books. On $10.50 semi the books you for receipt of awful face -so plain and yet with a strange everything. we to your first payment of $1.50 we will send 10 days' examination and let you be the you your free copy of Taylor's Transformer mistiness about it, so to speak, something AND HAVE sole judge as to their value. Practice. like the image upon the ground glass when 10 the focusing of the camera is not quite per- MONTHS fect. And, as I knelt there and looked upon TO PAY the sleeper, strange, weird, fantastic thoughts and feelings came to me. I could not keep the tears from my eyes. And those words of the man who had found her echoed and re- echoed through gloomy, awful corridors in my braid: FREE "Perhaps you -both of you -will love her, EXAMINATION too." Frontenac laid a hand on my shoulder. I raised my head; his look was upon the us sleeper's face, a strange, indescribable expression in his eyes. NO MONEY i "Poor little kid !" he said. IN ° At length came Nunatak and the others. ADVANCE FREE The scene rises before me as I write as i Examination vivid as though it had been yesterday -the Coupon sleeper there in her bed of cloudy crystal, McGraw-Hill the men clustered together before the ice Book Co., Inc., and looking in upon her in wonder and in SEND YOUR 370 Seventh Ave., awe. COUPON New York "Well," said Frontenac, at last, "now Gentlemen: -Send me the that NOW LIBRARY OF PRACTI- you all have seen her, we will cover her with CAL ELECTRICITY (ship- snow again, then enter the cave. There is ping charges prepaid), for 10 a door in that cavern, a massive door of days' free examination. If satisfactory, I will send $1.50 in ten solid rock. We know no more than that, days and $2 per month until the spe- save that the cavern is an extensive one. A McGraw -Hill cial price of $19.50 has been paid. If full exploration, with the limited time at not wanted, I will write you for return our disposal, is, in all probability, out of shipping instructions. Upon receipt of my Book Company first payment of $1.50 I am to receive a free the question." INC. copy of Taylor's Transformer Practice. We were a long time in finding the door, over which that awful carven harpy holds 370 Seventh Avenue Name eternal guard; and much we marveled that Captain Livingstone and Hampden had ever Home Address succeeded in finding their way out of this New York terrible labyrinth. City and State But at last we stood before that mysterious Employed by door. What was beyond it? (Continued on page 1253) Occupation S I. 4.1-25

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www.americanradiohistory.com Science and Invention for April, 1925 1253

The llAvfing Death Your Lifetime Opportunity jrwn pay,' 1251) (Cuntinu,.usands or and Punctuation. A Late Fire Bulletin. millions -I don't see as it makes much differ- Court Stories. Libel Laws, Copyright. ence either ways." }lints to Reporters. Personal Conduct. "You forget Captain Livingstone and Re- Writing and Condensing Stories. Hampden. See all the dust they removed Paragraphs and Short Items. Good and from the entrance." Bad Styles. Broadening the Vocabu- "Oh, I ain't forgot that, boss. And here's lary. Aids to Good Style. Special Stor- 'nother thing: I was wonderin' ies. Suggestions for Stories. Rhetoric. "Well?" -" Preparing Your Story. Don'ts for "I was wonderin', boss, if somebody-I Writers. Office Organization. Syndi- mean some thing- hasn't been here before cated Matter. Business Office. Mechan- us." ical Department. Hints for Headline "Livingstone and Hampden were here be- Writers. The Make -Up. The Country fore us." Correspondent, etc., etc. "That ain't what I meant, boss. I meant before us but after Cap Livingstone." Darwin Frontenac turned quickly, turned Only 250 at this Special Price- Applicants so that he stood squarely facing the musher. "What do you mean ?" he demanded. will receive preference as letters are received The next instant, however, Frontenac's ex- USE THIS COUPON pression, his whole manner, changed ; he laughed a little, as though ashamed of a THE PRESS GUILD, INC. momentary weakness. 66 -R West Broadway, New York, N. Y.

"Maybe you think that I'm pelton, boss ; Please mail me Henri J. Brockmeyer's complete Course in "Practical Jour- 5ut how do you explain that ?" nalism" at $2.98 which I will pay to the postman upon receipt of books. The musher was pointing toward a mark in the cavern floor. Frontenac stepped for- Name ward and bent over the impression. The Address rest of us, too, moved toward the spot. City State iu

www.americanradiohistory.com 1254 Science and Invention for April, 1925 "Well," queried Nunatak, and there was a tone of triumph in his voice, "what is -your explanation, bòss ?" EW. `FREE "A very simple one, Louis ; this mark was Trial at Home left by the foot of Captain Livingstone or discovery \ Hampden." for MEN "No, no !" said the musher. "Look at it and Women - close, boss. It's different!" He appealed to me. I bent over it. Surely Frontenac was right. But, as I continued to gaze upon that blurred impression, a doubt crept into my mind. I called myself a fool, though, for even permitting that doubt to enter my brain, to say nothing of letting it linger there. Some man, some thing here after Captain Livingstone and his companion! Why, the thought was preposterous. How, in the name of reason, could any -? Came a sudden sound behind us hollow, An Easy Way to Learn -a Our 10days' Free horrible voice. Trial proves that Wonder Mist revitalizes every cell CHAPTER XXIV and works miracles over - PHARMACY Comingpain and sickness. "AH- CONE -C A W N -GA" Physicians and plain folks explain how "Wonder Mist" HOME We straightened up and whirled to the has made them well, AT strong and happy. Graduate pharmacists are always in direction whence had come that sudden, mys- demand. The work is interesting and terious, horrible sound. For a few seconds, QUICK RESULTS pleasant and salaries are good. Many - what young men open drug stores of their own with the strong light we had had in and become independent. our eyes, nothing was visible there in the No Medicine dense "Wonder Mist" worksquickly; it'sscien- There's an easy way to learn pharmacy darkness. tific, goes alter the cause. That's why right in your own home in spare time, "Good God," exclaimed Loomis in accents results are quick,perm anent. Dr. Duncan, without losing a day or a dollar from of horror, and his words came Kewanee. III., writes, "Wonder Mist" is your present work. in echoes the finest thing I have ever used to relieve from the gloomy walls as though spectral pain, treatments are no pleasant all mypatients The International Correspondence beings had rolled them back like it." Use it at home. Save Doctor bills. Schools course in Pharmacy supplies the in fell mockery Brio sthenaturalmagneticbeautyofhealth. knowledge which it will be necessary for and fiendish gloating, "what was that ?" No dieting, exercise or drugs. you to have in order that you may pass "Surely," came the quiet voice of Darwin Board your State Examination. Frontenac, "it was a human being that Ñ éiv V Í'=1R`iock Just mark and mail the coupon printed spoke." below to the International Correspon- dence Schools, Box 6205 -D, Scranton, Pa., "If so," Nunatak said, "such a human and and full particularS anout the Pharmacy as no man of us ever heard before." Health Beauty; Course or any other work of your choice The next will come speeding to you by return mail. instant he gave a sharp exclama- _G enerátó rs tion and began stabbing the air with a TEAR OUT HERE , crooked finger. Partial list of ailments successfully treated with -'Wonder Mist." Earn Cash INTERNATIONAL CORRESPONDENCE SCHOOLS "Look, !" Men, women, without Box Scranton, Penna. look he cried. "There it comes! Catarrh Headache Rheumatism experience, earn liber- 6205 -0 Colds Goitre Skin Diseases in spare time. obligation on my part, please one See it! What did I tell you ?" Constipation Insomnia Slprofitshow -wonder Mist" Without cost or send Earache Lumbago Sa,, Throat to neighbors. Prove. full particulars about the subject before which I hava The creature was now visible quasi - Eye Dweaaes Nervousness Wogna sells marked an X in the list below - -a Falling Hair Neuritis o eight. Get offer, whole- Hay Fever TECHNICAL AND INDUSTRIAL COURSES human, fearsome figure. Piles Asthma sale prices. PHARMACY Civil Engineer "Stand together, men," came a hollow Beauty Aid ['Chemistry ['Surveying and Mapping Brings Work Foreman or voice, that of Hansen. "This is no man! no a ondÑëá Automobile Mine Engineer FREE Look tellsrcii in detail how high ['Agriculture and Poultry Steam Engineering 'Tis something from hell itself !" priced beauty specialists use it to ['Mathematics Gas Engine Operating improve Beall, and skin. ['Electrical Engineering Airplane Engines Radio The creature's visage could be made out Electrician Architect ['Mechanical Engineer Contractor and Builder now, though indistinctly -a death's head in Mechanical Draftsman Architectural Draftsman which eyes burned a fierce, Machine Shop Practice ['Concrete Builder with smoky, Railroad Positions Structural Engineer smoldering fire. BUSINESS TRAINING COURSES '°Tis a human being, boys," said Darwin Explains how Nikola Tes la discovered ['Salesmanship ['Business Management "Wonder Mist," how it works, why it ['Advertising Industrial Management Frontenac, "a man like ourselves -a man, hears. Tells how to conquer pain, disease ['Better Letters Personnel Organization though, from hell itself." and nervous trouble. ['Foreign Trade DTraffic Management Reveals Marvelous Scientific Dis- Stenography and Typing Business Law There could no longer be any doubt, and covery. Shows charts of human body, x- Business Englist Banking and Banking Law plains where pain. start, how to banish them. Offered 'Free Civil Service Accountancy (including C.P.A.) each of us, I believe, was more relieved than for a limited time only, to introduce "Wonder Mist," Railway Mail Clerk Nicholson Coat Accounting he would have cared to acknowledge: It Send for Free copy today. Common School SubjectsBookkeeping VI-REX CO., 211 S. Peoria St., Dept. 404 Chleago,111 High School Subjects Qrrtvate Secretary was a human being -such a man, though, as Illustrating UBusiness Spanish French I never had seen in all my life. Mail Coupon Send No Money VI -REX CO., 211 S. Peoria St., Dept. 0000, Chicago, III. Name He was naked save for a ragged cloth without bookadescribing ur VI-REX r' fWonderuMist" secrets. and Street Address about the loins. A kind of moccasin -now, details of your FREE Trial Offer. however, worn and cut to ribbons -incased Name City State his feet. His head hung forward, swaying, Occupation as he advanced, from side to side with a Address Persons residing in Canada should send this coupon to the lnVenationat Correspondence Schools Canadian. Limited. reptilian motion. The cheeks were hollow, Montreal. Canada. the eyes sunk deep in the sockets; face and City body were horrible with dust and gore; the skin was drawn tight over the bones, ren- The Famous KON -VER -TER Slide Rule dering his appearance skeletal, fearful. Instantly adds, subtracts. divides, a radia bo, s multiplies, dab parts for 6 : m converts fractions or tubes, etc. at ana -Nita less than regula, Straight toward us he came -this swaying decimals of an inch. Gives sines, prices,REIIse also sting on all circuits Ilse skeleton that yet was living. His lips were co-sines, versed sines. co- versed of broadcasting stators,canons and orner valuable data Send sines, tangents, co- tangents, se- e address 'u send you SOC boots FREEI in cants co- secants of angles direct- FREE SERVICI DVMRM[Mi. M. ácaertl N Y E... drawn back from the teeth a fixed and World he, you be ad (venal ly. Gives square roots. squares, ,o°ri;:'ñi.,ár.m..,ñ frightful grin. He kept muttering and cube roots, cubes and fifth roots a tE a oa, mumbling -the sounds seeming to issue not and powers of all numbers. Log- lIORWALK RADIOORd arithms, co- logarithms. anti -log- READE from the mouth, but through the very walls arlthms. Instructions with role. Dept. 52e 66 ST., NEW YORK DeLuxe Model $3. Cash or C.O.D of the chest. J. C. HAMILTON n NO On he came until he was within a dozen 7 Water St., Dept. B Boston. Mass. TAMME MORE feet of us. Then he halted and made to SKill the fear of stammering. Re- education the raise his right hand on high, his wild, burn- key. The widely famed Hatfield Method fully ing eyes fixed on Darwin Frontenac, that HONEYCOMB COILS outlined In an accurate, dependable, worth The Universal all -wave STAMMERING." 1J horrible voice, now raised to a high pitch, has inspired thousands. Free copy inductance. Back and INSTITUTE. 109 N. Dearborn. Chicago, III. sounding all the while. front panel mountings. THE HATFIELD Send 25c for Super But of a sudden the hand was arrested. It Het., R. F. and Honey- began fo sink; the fierce light left his eyes; comb Coil Circuits and PrintCards, Stationery, Your Circulars, Own Paper, etc. Complete Catalog. Complete Outfits se.ee up. Save money the grinning face seemed to set in a corpse- Print for others, big profit. Ali easy, rules like rigidity, and the man came pitching for- Chas. A. Arassten, Inc. sent. Write for catalog presses type, paper Dept. 4, 815 Main St. etc. THE PRESS CO.. L-47, Meriden. Ceno, ward into the arms of Frontenac. Buffalo. N. Y.

www.americanradiohistory.com Science and Invention for April, 1925 1255 Frontenac let him sink to the floor, and we turned him onto his back. "Sheer exhaustion," said Darwin, his hand over the man's heart, "and starvation." "Memaloose ?" asked Nunatak. "No ; the heart still beats, though slug- gishly." "One thing," Nunatak said, "he has been spared the horrors of thirst. He must have got water, else he could never have come to this pass. He would have been dead long ago." Frontenac pointed to a skin bag (or bottle) at the man's side, carried by a strap passing over the right shoulder. "A third full," he said, prodding the bag - which gave forth a gurgling sound as it moved-with his finger. "Funny," said Nunatak, "that he didn't eat the skin. I guess he preferred starvation to thirst. But where did he get the water ?" Frontenac took up the bag, removed the stopper and wet the man's forehead. "He has been badly wounded here," said Frontenac, indicating the right side of the head. "Must have got it in a fall." "And there," I said, pointing to the victim's right side. "Clean through the ribs." "And them ain't the only places," Nuna- tak remarked. "He is bruised and cut from the top of his head clean to the soles of his At Your Service feet." "Poor fellow !" said Frontenac. "'Tis a The courteous girl at the switchboard speaks the first word wonder that he's alive." "I fear me," said Nunatak, "that he ain't in more than two million conversations an hour. Presiding goin' to be alive very long." day and night at the busy intersections of speech, she is always "I fear that, too, Louis. But food may do wonders. So go back at once to the at the call of the nation's homes, farms and offices. camp -thanks to this string, you can go straight to the entrance and in to us again- Out of sight, and most of the time out of hearing of the so go back to camp, Louis, and bring " subscribers, little is known of the switchboard girl -of her Frontenac paused and turned his look from the musher's face to that of the Antarctican. training and supervision under careful teachers, and of her The were twitching, the lips writhing eyelids swift and skilful little is back in that horrible grin and the left hand work. Likewise, known of the engi- began a spasmodic twitching. neering problems necessary to bring the terminals of fifteen "Coming to," said Watson. "Or," Nunatak observed, "about to quit million telephones within the reach of a girl's arm, or of the this here old Vale of Sorrer." ceaseless work of maintenance which in fair weather and The eyes of the victim opened. I now saw, for the first time, that those eyes were storm keeps the mechanism fit and the wires open. blue -a bright, wonderful cerulean; yes, wonderful even through that horror which America's millions of people must have at their command filled them. means of direct and instant communication, and the Bell System He began to speak, his look fixed on the face of Darwin Frontenac. must ever be in tune with the demands of national service. "He is repeating something," Frontenac said. "Listen to that." These are the components of America's system of teleph- We listened for some moments to that ony: The best of engineering, of manufacture, of facilities strange verbal repetition. - "What is it ?" Frontenac asked. and a personnel trained and eager to serve. "Ah- cone- cawn -ga," I told him. The others nodded. "That," concurred Nunatak, "is the very AMERICAN TELEPHONE AND TELEGRAPH COMPANY word that he's savin'." "Or," Frontenac suggested, "words." AND ASSOCIATED COMPANIES "Ah -cone- cawn -ga!" said the Antarctican once more, for the first time looking me in 'BELL SYSTEM the face. "If," Nunatak exclaimed, "he could only One Policy, One System, Universal Service tell us!" The victim suddenly raised himself into a sitting position ; almost as suddenly, though, ATTERY CHARGING 'gyy o X150 t° #300 MONTHLY ,NCO, E he collapsed back into Frontenac's arms. It You can easily add $150 to $300 every month to your income with Ll' was patent that the man's will was in a grim r your own battery charging business. Only $35 cash brings a com- ` Ii plete HB One Day Battery Charging outfit, ready to use. Your struggle. He raised his skeleton arm and monthly profits easily carry the small monthly payments. 30 days pointed, his lips moving in what, for a Vá free trial on money -back guarantee. The best and lowest -priced moment, I thought was a smile -yes, a joy- Mr/ complete outfit on the market. No experience required to operate. Write for free bulletin. Start your own money- making business. ful smile. The next í ONE aasa;n moment, however, I t` .a HOBART BROS. CO. Box S4 TROY, OHIO - believed it to be a look of fear and horror. MO M PRCFlTS I raised my eyes in the direction indicated _3O DAYS FREE TRIAL -MON , G : ,_i, I by his skeleton finger, and a shiver ran through me as they lighted upon that monster above the door. EARN $2,000 TO $10,000 A YEAR "Ah- cone- cawn -ga!" said the Antarctican. STUDY AT HOME The hand dropped to the floor as though OPPORTUNITY is at your the arm had been snipped from the body; door. the head sank forward, then rolled sidewise Learn Airplane Engineering now. in horrible fashion as Frontenac let the Write for Free Catalog corpse sink down to the cavern floor. WESTERN AIRPLANE (To be CORPORATION continued) Dept. S 4 Monadnock Block CHICAGO

www.americanradiohistory.com 121)(' Science and Invention for April, 1925

nmm,mmn,ammIIm<,nn,,,.. mnm1,1,... 111,1nI,nm,n,::1amna,1!-mm1:,,a1a116,3 Scientific Pun7de $100 a Week Answers (Coufinu, d from rage 1213) in this ill1111, ii111a,,,ma111, aa,u1. COMPARISON OF TEMPERATURES Fascinating Business Liquids have a tendency to superheat; that- is, to get hotter than the vapor that issues from them at big the boiling point. This i ;-especially true of liquids EARNmoney a s -a in vessels with smooth sides.- A dish with rough

! - cartoonist sides or one containing objects with more or - less BILLION DOLLAR RESTAURANT Millións of dol- rough surfaces seems to afford less chance for lars were spent superheating, for the bubbles pf steam form readily INDUSTRY NOW last year on comic wherever there are points or projections, -and, wi!h OPEN TO YOU strips, political the consequent liberation of heat energy in the Cafeterias, Lunchrooms, Restaurants, Dairy Lunches, Sand and car. wich Shops, Luncheonettes Now Otter You Big Opportunities sport steam, the temperature of -.the liquid is maintained -No Previous Experience Needed -Earn $2500 to $10.000 toons, animated nearer the true boiling :point than is `the case with a Year This Amazing New Way. cartoons, e t c . 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The field literally in this fast -growing field been so many, so varied single oppositely faced (WB) card. Hence the ad- teems with big pay posi- vantage lies with one who tions and my free Employment Bureau is getting many or so high- paying. the bets that the under calls for my graduates. surface of any drawn card is like the top. I Guarantee to Train You - Right at home in your spare time in a few short weeks to THE DIFFERENTIAL PULLEY SYSTEM be a Lewis- Trained Restaurant Expert. You can 'qualify Easy to Learn CARTOONING for a Let X be the tension of 2nd salary of $2500 to $10.000 a year, and I show you each of the ropes, B exactly how to start own business C, when a force of 200 lbs. is your on small capital, or at Home in Spare Time applied to A. Then, put Am in touch with positions, just as you wish. Let me considering the moments tending to turn the wheel show you how hundreds of my graduates are winning success Regardless of how little you know about car- and axle around, we have 200 X 10/9 r + Xr --big pay. fine meals, fascinating work in this wonderful now, can for a X field. Let nie prove why my methods are nationally en- tooning you easily qualify position = X 10/9 r or X - 2,000 lbs. tension in ropes dorsed and in this attractive, high -salaried business. This B and C. But since the used by leading. successful restaurant operators, pull on the car is equal to men earning $5000 to $50,000 a year and more. home -study method starts you at the simplest fun- the sum of the tensions on t:.e ropes, it will equal Write for This Amazing Free Book damental principles of cartoon -making and takes 2,000 + 2,000 + 200 or 4,300 lbs. Don't send a cent. Just drop a card and our big illus- you through every branch of humorous and serious trated book, "Fortunes from Feeding Folks," will come by cartooning. You will be amazed at how quickly IS THE OBJECT PURE GOLD? return mail. Write today, NOW, before You forget. It it teaches you means a big chance for you. to draw salable work. Many stu- Suspend the object and the nugget of gold from THE LEWIS TRAINING dents of this method began to sell their drawings opposite ends of a bar and balance a SCHOOLS before they were half through their courses. The the bar on CLIFFORD LEWIS, President knife edge. Then lower the bar until both the gold Dept. R-340? training paid for itself long before they finished and the object in question are completely sub- Washington, D. C. it. merged in water. If the bar still balances the object Learn cartooning this easy way. Enjoy the is pure gold, fascinating life of a for the moments due to the buoyant successful cartoonist -easy force of the water will be the sante on each side hours, freedom from routine, your own boss, and of the knife $3,000 to $15,000 a year for this work that is edge. If the bar becomes unbalanced by the water it will show that the object is not play ! pure gold. Send for FREE BOOK AN EXPERIMENT IN DIFFUSION Learn more about the wonderful opportunities ill The porus jar which separates the air within it Cartooning, and details about this remarkable home- from the air and gas around it will let both gases study method. A hand- pass through quite readily. However, the gas from somely illustrated booklet lite outside gets in faster than air on the inside has just been prepared gets out because the gas molecules move with which, upon request, will greater rapidity than the molecules of air. The be sent to you without the result is a temporary increase in pressure within slightest obligation. This the jar. booklet gives a thorough outline of the cartooning CALCIUM CHLORIDE AND IRON field, and explains in de- SULPHATE tail this wonderful new Calcium chloride will apparently increase in method of teaching Car- weight when exposed to the air because it absorbs tooning. Send for it to- water readily from its surroundings. On the other MY U. S. GOVERNMENT JOB day! Washington School How hand. iron sulphate tends to lose water and hence "Yes, dear -I now work for 'Uncle Sam.' Today of Cartooning, R o o m to Become a gets lighter. I received appointment. 264C, 1113 -15th St., CARTOOIIT$ "Tomorrow, I go out on my first Railway Mail N.W., Washington, D. C. OSMOSIS run to Washington, D. C. From now on I will The experiment with the sac of molasses in water travel on pass and see my country. Washington School of Cartooning is similar in some ways to the one on diffusion "I commence at $1600 a year and expect to raise Room 264C, 1113 -15th St., N.W.,Washington, D. C. described above. In this case the bladder (or other to $2300 within a short time. "I have a Summer me, animal membrane) which keeps the molasses and vacation with full pay and Please send without obligation, your Free water apart while apparently water-proof will ac- very pleasant work." Booklet on Cartooning and full details of your home -study method of teaching tually let water slowly pass through. It will also Cartooning. let molasses pass through but not as readily. Hence Thousands of U. S. Government Jobs are obtain- the water gets into the sac faster titan the molasse; able by men and women 13 up. Mail the coupon TODAY Name gets out and thus increases the pressure within SURE. You may then soon find yourself (Print Name Plainly) the sac. in a well paid U. S. GOVERNMENT JOB. Cut Here Address WEIGHT OF IRON OBJECT FRANKLIN INSTITUTE Iron objects in the earth's magnetic field soon Dept. B -183. Rochester, N. Y. become more or less magnetized themselves. A Send me at once, free of charge, (1) List of U. S. Govern- City State "north seeking" pole appears in the lower and ment Jobs obtainable, (2) Full information regarding salaries, hours, duties, etc. (3) Send free sample examina- northern end and a "south seeking" pole at the tion coaching. (1f under 16, please give age - ) upper and southern end. (In this connection try testing the top and bottom of various iron objects. Name such as radiators. hitching posts, etc.. with a compass.) If the intensity of the earth's magnetic Address field were greater at one pole of the obiect than F®r Runs 57 MIlIles at the other the object would be urged downward and northward, or upward and southward, depend- on GaIlIl®n ©f ing on which pole was in a region of greater field intensity. But for objects of ordinary size, the IMPLES Gas®Ilñne earth's field is constant and hence there is no net lour akin Can Be Quickly Cleared of Pimples, Blackheads. force tending to move the object up Or down, north Acne Eruptions on the face or body. Barbers Itch. or south and, therefore, no magnetic force affect- Eczema. Enlarged Pores and Oily or Shiny Skin. A new automatic and self -regulating de- ing its weight. FREEWrite today for my FREE BOOKLET, A CLEAR -TONE Sant,"-telling how I vice has been invented by John A. Stransky, BUOYANCY PROBLEM eared myself after being afflicted 15 yesca. E.S.GIVENS,168 Chemical Bldg., 207 Fourth St., Pukwana, South Dakota. By Archimedes' principle, an object more or less Kansas City.Mo. submerged in a liquid is buoyed up by a force equal with which automobiles have made from 35 to the weight of the liquid displaced. Since the volumes of the two objects are the equal in this TO THE RADIO DEALER to 57 miles on a gallon of gasoline. It re- case might it seem that the displacement would be Let us explain how you moves carbon and reduces spark plug trouble equal for both and, therefore, the buoyant force can make the sale would he same of our publications a worth while, well paying the for both. But since the open part of your and overheating. It can be installed by any end of the longer can is forced to lower business. a depth Write now and prepare for the Fall and than is the open end of the shorter can, it is evi- Winter trade. one in five mniutes. Mr. Stranskv wants dent that air within the former is more compressed distributors and is willing to send a sample than the air in the latter, less water is displaced EXPERIMENTER PUBLISHING CO. by it, and hence it requires less force to submerge 53 Park Place New York City at his own risk. Write him today. -Adv. the longer can.

www.americanradiohistory.com Science and Invention for April, 1925 1257

IInI,,,,,I1n,11111111111 ,,,,,,11,111111,,,,,,n1,,,,1,1111n,,,,,n1,,,II,,,,,,,II,,,,,,,,,, ,. .,P adio ái)r®adcasQ REVISED AND CORRECTED TO DATE. First Group of Figures Indicate the Power in Watts in the Antenna of the Transmitting Station. The Second Group Gives the Wave-Length.

ili1111111111na111,111em11111e1n111n111111n.11111>nn111111111111111III11111111111111111111en1111111111IIIIIIIIIII I111111r3 Power Call & Wave Letters Location and Name Length KDKA East Pittsburgh, Pa.. Westing- house Electric & Mfg. Co..1000 -309.1 KDPM Cleveland, Ohio, Westinghouse Electric & Mfg. Co 500 -270 KDPT San Diego, Calif, Southern Electrical Co 50-244 KDYL Salt Lake City, Utah, New- house Hotel 50 -250 KDYM San Diego, Calif., Savoy The- atre 100 -280 KDYQ Portland, Ore., Oregon Insti- tute of Technology 50-360 KDZB Bakersfield, Calif., Frank E. Siefert 100 -240 KDZE Seattle, Wash., Rhodes De- partment Store 100 -270 KFAB Lincoln, Neb., Nebraska Buick Auto Co. 200 -240 KFAD Phoenix, Ariz.. McArthur Artificial lightning was first publicly demonstrated Bros. Mercantile Co 100 -360 on June 5, 1923, in the laboratory of the General KFAE Pullman. Wash., State College Electric Company at Pittsfield, Mass., when a two - of Washington 500 -330 million -volt spark crashed into this miniature village. KFAF Denver, Colo., Western Radio Corp. 500 -278 KFAJ Boulder, Colo., University of Colorado 100 -261 KFAN Moscow, Idaho, The Electric Shop 50-360 What's the use of KFAR Hollywood, Calif., Studio Lighting Service Co 100-227 KFAU Boise. Idaho, Independent School District of Boise artificial lightning? City, Boise High School 500 -275 KFAW Santa Ana, Calif., The Radio Den 10-280 KFBB Havre. Mont., F. A. Buttrey is & Co. 50-275 It mainly experimental, KFBC San Diego. Calif., W. K. Azhill 5 -278 KFBG Tacoma, Wash., First Presby- aiding General Electric terian Church 50-360 KFBK Sacramento, Calif., Kimball - scientists to solve high power Upson Co. 100 -283 KFBL Everett, Wash., Leese Bros 15 -224 transmission problems. Many KFBU Laramie, Wyo., Bishop N. S Thomas .. 50 -270 such experiments yield no KFCB Phoenix, Ariz., Nielson Radio Supply Co. 10-238 immediate return. KFCC Helena, Mont., First Congrega- tional Church 10-248 When the General KFCF Walla Walla, Wash., Frank A Electric Company But in the long run this work Moore 100 -256 was formed, there KFCL Los Angeles, Calif., Leslie E was great need of is practical and important. Rice, Los Angeles Union organized electrical Stock Yards 500 -236 - It is of study which KFCP Ogden, Utah, Ralph W. Flygare 10-360 research. The Corn part the KFCV Houston, Tex., Fred Mahaf- pany's laboratories, in go if fey, Jr. 10-360 Schenectady and must on unceasingly this KFCY Le Mars, Iowa, Western Union elsewhere, have powerful force, is College 50-252 pioneered in increas- Electricity, KFCZ Omaha, Nebr., Omaha Central High School 50-258 ing the service of to be fully tamed and enlisted KFDD Boise, Idaho, St. Michaels Ca- electricity and in re- thedral 10-252 ducing its cost. in your service. KFDH Tucson, Ariz., University of Arizona 50-268 KFDJ Corvallis, Ore., Oregon Agri- cultural CoPege 50-360 KFDL Denver, Colo., Knight -Campbell Music Co. 5 -226 KFDM Beaumont, Tex., Magnolia Pe- ELECT l. 500 GENERAL Co. -315.6 IC troleum KFDX Shreveport, La., First Baptist Church 100 -250 KFDY Brookings, S. Dak., South Da- kota State College of Agri- culture and Mechanic Arts 100 -273 KFDZ Minneapolis, Minn., Harry O 5 -231 BLANK CARTRIDGE PISTOL Iverson rThe(Traffic Cop Protection against Barglars. Trampa. & Doge KFEC Portland, Ore., Meier & FERBEND -TIYÇtr PRICE Frank Co. 50-248 Jlir KFEL Denver, Colo., Winner Radio 9' the aiQbW7111, .t.. 1 SOc. 50-254 Add a Ferbend Wave Corp. to Radio Set & Co. Trap your KFEQ Oak. Nebr., Scroggin 011-11, and "Police your recep- Bank 100 -268 tion. Regulate traffic. Dodge. Iowa. Auto Elec - Guaranteed to tune out \PAID KFER Fort any interfering station. tric Service Co 10-231 but Web mans and M Widely imitated fictive; ra. dellcd on KFEX Minneapolis, Minn., Augsburg never equalled. The latest type of Revolter: Seminary 100 -261 original and only suc- appearance alone is cessful WAVE TRAP. gnongh to meare a burg. KFFP Moberly, Mo., First Baptist ser. W h n loaded tt me Now in its third year. e as effective as a real Church 50 -266 Sent Postpaid upon re- revolver without danger tattle. It takes stead- of $8.60 or C O. D. Cal. Cartridges obtainable every- KFFR Sparks, Nev., Nevada State ceipt sod .22 Bleak Snowierxpress. SOcv0post. plus . Send for Free Booklet pwhere. Journal 10 -226 postatto aid. BlankClank Cartridges,.cartridges, by exp.ees.5oe per 100. FERBEND ELECTRIC CO. Wls. KFFV Lamoni, Iowa, Graceland Col - 31 E. So. Water St. Chicago JOHNSON SMITH Si CO. Dept. 332 Rawno. ti lege 100 -250 KFFY Alexandria, La., Louisiana Col- lege 50 -275 nestling Book ,&"-"r" BECOME A LIGHTNING Teile how to be a great athleteFREE and acien- KFGC Baton Rouge, La., Louisiana ` tific restler - how to WIN. Startling secrets ro taught in wonderful lessons by world's ham - State University 100 -268 it j TRICK CARTOONIST" Farmer KFGD Chickasha, Okla., Oklahoma F, l Malte money chalk talking. Send $1 for nanny strong tic. HandleFrankbig omen with program of trick drawings. with instructions by a self defense. Be a leader. Men and College for Women Q. A. lk boys write for Free Book today. State your age. Teeters) 50 -252 Circular free. Baldan Art Service. Dept.f 4. Oshkosh.nWit. armetBmtaSehooi 1254 RailwayBlds.,0maha,Net

www.americanradiohistory.com 1258 Science and Invention for April, 1925 Power Call & Wave Letters Location and Name Length KFGH Stanford University, Calif., Leland Stanford Junior Uni- What will you versity 500 -273 KFGQ Boone, Towa, Crary Hardware Ce 10 -226 be doing one year KFGX Orange, Tex., First Presby- terian Church 500 -250 KFHA Gunnison, Colo., Western State College of Colorado 50-252 from to-day? 'd. ., ft KFHJ Santa Barbara, Calif., Fallon & -á Co. 100 -360 BUNGALOW KFHL Oskaloosa, Iowa, Penn College 10 -240 6 Three KFHR Seattle, Wash.. Star Electric WE PAY THE hundred and sixty-five days from & Radio Co. 100 -263 rr now -what? KFI Los Angeles, Calif., Earle C IaET US ship you direct Anthony (Inc.) 1500 -469 from our mill all the Will you KFIF materials complete for a still be struggling along in Portland, Ore., Benson Poly- Sterling cut -to-fit Isom*, the same old job at the same old salary technic Institute 100 -248 (not portable) and save you KFIO Spokane. Wash., North Cen- four big profits on lumber. -worried about the future -never tral High School 50 -252 hardware mill-work and la- quite able to KFIQ Yakima, Wash., First Metho- bor, besides a proved 20% make both ends meet - saving in waste. Substan- standing while dist Church 50-256 418 tially built and lasting. Sat- still other men go ahead? KFIU Juneau, Alaska, Alaska Elec- 5 ROOMS infection Guaranteed Or tric Light & Power Co 10-226 Your Money Back l One year from today will you still be KFIX Independence, Mo., Reorgan- Buying putting off Direct Saves t/a your start toward success - ized Church of Jesus Christ A BO V E prices include of Latter Day Saints 250 -268 everything complete -all thrilled with ambition one moment and limber cut -to-fit (highest grade KFIZ Fond du Lac, Wis.. Daily Com- Only) windows. doors, flooring, then cold the next -delaying, waiting, monwealth & Seifert Radio ehingfee, lath, glass. paints, varnish, fiddling away the precious hours that Corp. . 100 -273 FREE CATALOG KFJB Marshalltown, Iowa, Marshall yylainiy marked and easily assem- will never come again? with many other dire according to drawings and Electric Co. 10 -248 beautiful homes directions we furnish. KFJF Oklahoma, Okla., National Ra- at $478 to $4,797 $1606 Homeinc1udesdonble Don't do it, man -don't do it. dio Mfg. Co. 225 -261 - all at big sav- room houseincludes-m miic wails KFJI Astoria, Ore., Liberty Theatre 10-252 ings. Garages and floors; for double add 589. There is no greater tragedy in the KFJK $73 Bristow. Okla., Delano Radio and up. International MITI & Timber Co, world & Electric 2271 South Wnnon Ace. than that of a man who stays in Co. 100 -233 Bay city, the rut all his life, when with just KFJM Grand Forks, N. Dak., Univer- Mich. a sity of North Dakota 100 -280 little effort he could bring large success KFJR Portland, Oregon, c/o Ralph within his grasp. Schneelock Co. Ashley C. Dixon & Son.... 5 -263 Make up your mind today that you're KFJX Cedar Falls, Iowa, Iowa State NEW VEST POCKET Teachers' College 50 -280 going to train yourself to do some one KFJY Fort Dodge, Iowa, Tunwall thing well. Choose the work you like Radio Co. 50-258 ADDING MACHINE best in the list below, mark an X beside KFJZ Fort Worth, Tex., Texas Na- Adds as rapidly and accurately as a tional Guard, 112th Cavalry 20-254 $300 machine, yet fits the vest pocket. it, mail the coupon to Scranton, and KFKA Mechanically perfect. Easy to operate Greeley, Colo.. Colorado State -nothing toget outof order. Everyone without cost or obligation, at least get Teachers' College 50 -273 who uses figures should own one. KFKB Milford, Kans., Brinkley -Jones Counts Up to the full story of what the 1. C. S. can do Hospital Assn. 999,999,999 you. 500 -286 Total visible at all times. A pull of the finger clears it. for KFKQ Conway, Ark., Conway Radio Don't carry a pocket full of pencil stubs and scrap Laboratories - 100 -250 _- - -- paper to do your figuring. Carry a Ve -Po-Ad. KFKU Lawrence, Kans., University of Lena ne money, INTERNATIONAL CORRESPONDENCE SCHOOLS 10 Days Trial Just name Box Kansas 500 -275 dress and 6204 -D; Scranton, Penna. KFKV Butte, Mont., F. F. Gray we will lend machine _postpaid. Without cost or obligation on my part, please ten me 50 -25: Pay postman on delivery $2.95. Use it for how I can qualify for "the position or In the subject before' IFKX Hastings, Nebr., Westinghouse 10 days to prove it does all we claim. If which I have marked an X: Electric & Mfg. Co., .'..1000 -288.3 not perfectly KFLA y, Limited aup»ly, Send order today. BUSINESS TRAINING COURSES Butte, Mont., Abner R. Wilson 5 -258 KFLB Menominee, Mich., Signal Elec- Reliable Adding Mach. Corp., Dpt. 144 Business Management Salesmanship 170 W. Washington St., Industrial Management Advertising tric Mfg. Co. 50-248 Chicago, Ill. alPersonnel Here's a money maker. Everybody Organization Dilater Letters KFLE Denver, Colo., National Educa- wants one. Splendid profit. Write Traffic Management Show ° Card Lettering tional Service - 25 -268 for special offer. []Business Law ° Stenography and Typing KFLQ Little Rock, Ark., Bizzell Radio °Banking and Banking Law ° Business English Accountancy (including C.P.A.) °Civil Service Shop 20 -261 LOUD Nicholson Cost. Accounting p Mail Clerk KFLR Albuquerque, N. Mex.i Univer- TUBE EAKINß Railway School sity of. New Mexico 100 -254 °Privatep Secretary High Set Subjects m KFI.0 San Benito, Tex., Spanish French Illustrating San Benito Radio Corp. 15 -236 TECHNICAL AND INDUSTRIAL COURSES KFLV Rockford,- Ill., Swedish- Evan- Electrical Engineering Architect gelical Mission Church 100 Electric Lighting pArchitects' Blue Prints -229 Mechanical KFLX Galveston, Tex., George R Engineer Contractor and Builder Clough FULLY GUARANTEED Mechanical Draftsman D Architectural Draftsman 10 -240 Machine Shop Practice D Concrete Builder KFL7, Atlantic. Iowa, Atlantic Auto- Railroad Positions Structural Engineer mobile Co. ONG DISTANCE RADIO Gas Engine Operating 100 -273 Chemistry Pharmacy KFMB Little Rock, Ark., Christian Users everywhere Miraco Civil Engineer Automobile Work report DEALERS Surveying and Mapping Churches of Little Rock -254 Tuned Radio Frequency sets get Our proposition's Airplane Engines programs coast to cost; tinnier- s Writ, Metallurgy Mining D Agriculture KFMQ Fayetteville, Ark., University form sets 3 times as costly. Send winner. Steam Engineering and Poultry for proof they are radio's most ['Radio ['Mathematics of Arkansas 500 -275 amazing values. One tube guaran- KFMR Sioux City, Iowa, Morningside teed, completely assembled long distance outfit, only$14.35. Three Name College 10-261 tube(above),S19.5O.Five tube 575 Street 3 -6.24 KFMT Minneapolis, Minn., George W SEND POSTAL TODAY Address Young . 100 for latest bulletins and special -231 offer. it will interest you. KFMW Houghton, Mich., M. G. Sate - City State MIDWEST RADIO CORP'N ren 50 -266 .ioneer Bladders of Seta 408. M E. 8th St., Cincinnati, Ohio Occupation KFMX Northfield, Minn., Carleton Col- lege 500 Persons residing in Canada should send this coupon to the -336.9 International Correspondence Schools Canadian, Limited. KFNF Shenandoah, Iowa, Henry Field Montreal, Canada Seed Co. 500-266 KFNG Coldwater, Miss., Wooten's Radio Shop 10-254 KFNL Paso Robles, Calif., Radio Broadcast Assn 10 -240 KFNV Santa Rosa, Calif., L. A. Drake Battery and Radio Supply Shop 5 -227 KFNY Helena, Mont., V. Kemp Rob- Chlorine erts Gas 50 -248 KFNZ Burlingame, Calif., Royal Radio Co. 10-231 \ \ Agents-Salesmen KFOA Seattle, Wash., Rhodes Dept `` Newest invention out -going like wildfire; Chlorine Store 500 -455 Gas is taking the country by storm. The Chlori- KFOC Whittier, Calif., First Chris- ON ONE TUBE tian Church BIG FREE BOOKLETr tells the story. nator is the only gas machine for home 100 -236 California users or indivi- KFOD Wallace, Idaho, The Radio of CROSS COUNTRY CIRCUIT hear Atlantic Coast. dual use. Gives the same gas as used by President Canada, Cuba, Mexico and Hawaii. Atlantic Shop 10-224 hear England Coast users Coolidge and other officials in Washington. Chlorine KFOJ Moberly, to California. Our new plan makes this Mo., Moberly High set easiest and cheapest to build. One hour puts in Gas destroys the bacteria of adult and childhood School 5 -246 operation. One tuning control. No soldering. Any diseases to which all KFON Long Beach, novice can do it. BIG BOOKLET FREE or are exposed daily. Any person, Calif., Echophone instructions complete anywhere can now Radio Shop 100 for 25c stamps or coin. use Chlorine Gas with absolute -234 'VESCO RADIO CO. Box SI -117 Oakland, Calif. safety and almost miraculous results with KFOO Salt Lake City, Utah, Latter the Day Saints University 10-261 Chlorinator. Not a patent medicine-used and en- KFOR dorsed David City, Nebr., David City SEX KNOWLEDGE BOOKS by physicians. Salesmen make money fast Tire & Electric Co. (How- ADULTS! -write for complete details. instructive, authoritative, profusely il- ard A. Shuman) 20 -226 lustrated In natural colora, etc. The worth -while sort. Con- KFOT Wichita, Kans., College tains everything one should know both before and after Hubert A. Myers Laboratories, 148 Erie St., Toledo, O. Hill riage to enioy health mar- Radio Club 50 and happiness. Large Catalog, Ile. -231 F. SMETANA & CO. OWOSSO. MICH.

www.americanradiohistory.com Science and Invention for April, 1925 1259 Power Call & Wave Letters Location and Name Length KFUU Richmond, Calif., Hammel Mfg. Co. 100 -254 KFOX Omaha, Nebr., Technical High School 100 -248 KFOY St. Paul, Minn., Beacon Radio Service 50 -252 KFOZ Fort Smith, Ark., Leon Hudson Real Estate Co 20 -233 KFPG Los Angeles, Calif, Oliver S. Garretson 10 -238 KFPH Salt Lake City, Utah, Harold C. Mailander 50 -242 KFPL Dublin, Texas, C. C. Baxter 15 -252 KFPM Greenville, Texas, New Furni- ture Co. 10 -242 KFPP Olympia, Wash.. G. & G. Radio & Electric Shoo 20 -236 KFPR Los Angeles, Calif., Los An- geles County Forestry De- partment 500 -231 KFPT Salt Lake City, Utah, Cope & Johnson 500-268 KFPV San Francisco, Calif., Heintz & Kohlmoos 50-236 KFPW Carterville, Mo., St. Johns Church 20 -268 KFPX Pine Bluff, Ark., First Presby- terian Church 100 -242 KFPY Spokane, Wash., Symons In- vestment Co. 100 -283 KFQA St. Louis, Mo., The Principia 50 -261 KFQB Fort Worth, Texas, Search- light Publishing Co 100 -254 KFQC Taft, Calif., Kidd Brothers Radio Shop 100 -231 KFQD Anchorage, Alaska, Choy i n Supply Co. 100 -280 KFQE Colorado Springs, Colo., Dick- enson -Henry Radio Labora- tories 10 -224 RFQG Los Angeles, Calif., Armory Exposition Park, Southern California Radio Assn. 50 -229 KFQH Burlingame, Calif., Radio Ser- vice Co. (Albert Sherman) 50-231 RFQL Muskogee, Okla., Oklahoma Free State Fair Assn. 20 -252 KFQM Austin, Texas, Texas Highway Bulletin 100 -268 KFQN Portland, Ore., Third Baptist Church 5 -283 KFQP Iowa City, Iowa, George S. Carson, Jr. 10-224 KFQR Oklahoma, Okla., Walter L. Ellis 50 -250 KFQT Denison, Texas, Texas National Guard, 36th Signal Company 10-252 KFQU Holy City, Calif., W. Riker 100 -234 KFQV Omaha, Nebr., Omaha Grain Exchange 100 -231 KFQW North Bend, Wash.. C. F. Knierim Photo Radio & Electric Shop 50-248 KFQX Seattle, Wash., Alfred M. Hub- bard 500 -233 KFQY Belden, Nebr., Farmers State Bank 10-273 KFQZ Hollywood, Calif., Taft Radio Co. 250 -240 KFRB Beeville, Tex., Hall Brothers. 250 -248 KFRC San Francisco, Calif., Radioart Studio, Whitcomb Hotel 50 -278 KFRF Alexandria, La., W. R. Brown 10 -242 KFRH Grafton, N. D., The Radio Shop (Martin L. Monson) 10-268 KFRJ Conway, Ark., Guy Simmons, Jr. 10 -250 JO- DAYS FREE TRIAL - MONEY BACK IF NOT SATISFIED KFRL Grand Forks, N. D., Men's Club of First Presbyterian THE NEW iffikt SELF FILLER Church 10 -240 IMPROVED I GREATEST VALUE EVER OFFERED KFRM Fort Sill, Okla., Lieut. James P. Boland, U. S. A. 50 ACTUAL f -263 Hanford, Calif., M. Laurence SIZE the %erfect `Writing Instrument 150 KFRN LONG Short 5 -224 eU" Writes with ink free and easy as a lead pencil, with- , 3ENTS WANEi7 out a miss, skip or blur. Its steady uniform flow KFRO Fort Worth, Tex., Curtis Print- of ink actually improves your hand writing. ing Co. 50 -246 blot, scratch, leak, or soil hands. KFRP Redlands, Calif., Trinity Epis- 'Patent Makes3 or4 Carbon copal Church 10-211 Automatic Copies With Original lit Ink. Radio Market 14 kt. gold teed Anyone can write with your In- KFRQ Portland, Oreg., prevents slogging. kograph, no style of writing Service Co. (Harry M. Made of best grade, or pressure ran ben., 5 spread, injure or Schultz) -213 highly polished, hard rubber, tort its 14 kt. KFRW Olympia, W a s h., h est class workmanship. gala point. United ocket clip attached makes it Churches of Olympia 100 -220 en Instrument of refinement. KFRX Pullman, Wash., J. Gordan Tne e NOGRAEM 'You'll never use a fountain pen once you try Klemgard 10-217 ¡ an Inkograph. No complicated mechanism to KFRY State College, N. Mex., New That hem smooth round bat like clean or get out of order. SEND NO MONEY. oolnt,nbIch gildes with easeover Pay postman $1.50 plus postage. Year's guarantee certificate Mexico College of Agricul- the sest saper and makes sasores absolute satisfaction. Write name and address plainly. ture and Mechanic Arts 50-266 Possible writhe IC in ink as ra yidly INKOGRAPH New York KF Z Hartington, Neb., Electric Shop as with the softest lead pencil. CO., Inc. 201 -65 Centre St (P. M. Thies) 15--222 4 KF G Los Angeles, Calif., Echo Park Evangelistic Assn. 500 -278 RF' Helena, Mont., Van Blariconr Straightens Shoulders Co. 10-248 Mailing. Lists -Increases Pep Will help won izerease Bales THE NATURAL BODY BRACE-Corrects KF I J Breckenridge, Minn., Hoppert Sent for stooping shoulders, straightens the back, gives Plumbing & Heating Co. ndwe s on too dso ee ssEn the lungs chance for normal expansion, induces 50-242 $ mt proapoeeectivef rusóm- Dam. aof your comfort, KFiIL Ga'veston. Tex., Thomas Gog - stionci.state ar it,ocet- IndlrLi- proper breathing. Brings restful relief. Profession . 3udnase Cgnca-oa- energy, and pep. For men and women. gan & Bros. Music Co 10-258 asia, lo aian d KF M Colorado Springs, Colo., W. mi each Costs nothing to try It D. Corley 100 -242 99 Write for 30 days free trial offer and free book. KF I O St. Louis, Mo., Concordia Col- NATURAL BODY BRACE CO.. lege 500 -545.1 Howard C. RashaIL286 Rash Bldg.. Salina, Kansas

www.americanradiohistory.com Science and Invention for April, 1925 Power Call & Wave Solid Letters Location and Name Length Rubber KFUP Denver, Colo., Fitzsimons Gen- eral Hospital 50-234 Case KFUQ San Francisco, Calif., Julius Brunton & Sons Co. 5 -234 KGB Tacoma, Wash., Tacoma Daily Ledger 50 -250 "DE LUXE" KGO Oakland, Calif., General Elec- COAST tric Co. 1500 -312 To TUBE KGU Honolulu, Hawaii, Marion A COAST 5 Mulrony 500 -360 KGW Portland, Ore., Portland Morn- ing Oregonian 500 -492 KGY Lacey, Wash., St. Martins Col- NO MONEY lege 5 -258 SEND GENUINE RUSH NAME AND ADDRESS KHJ Los Angeles. Calif., Times - LICENSED FOR PROPOSITION Mirror Co. 500 -395 TODAY PA RTS KHQ Seattle, Wash., Louis Wasnler (Excelsior Motorcycle & Bi- cycle Co.) 100 -360 KJQ Stockton, Calif., C. O. Gould 5 -273 KJR Seattle, Wash., Northwest Ra- World 6-Volt Storage Batteries dio Service Co. 50 -283 are famous for their guaranteed Approvedand KJS quality and service. Backed by Listed as Los Angeles, Calif., Bible In- years of Successful Manufacture Standard by stitute of Los Angeles 500 -252 and Thousands of Satisfied Users. KLS You save Leading Oakland, Calif., Warner. Bros Live young men wanted in every town to own, 50% and get a Radio Supplies Co. operate and take orders 2 Authorities 250 -360 for this big 5 tube De -Year Guarantee Bond including Radio KLX Oakland, Calif., Tribune Pub- Luxe Coast to Coast Neutrodyne set. Genuine In Writing News Labor- lishing Co. 500 licensed Hazeltine parts, synchronized and World Battery owners "tell -509 their friends." atories, Popular KLZ Denver, Colo., Reynolds Radio matched. Loud, clear, powerful. Delicate tun- That's our best Science Insti- Co. ing. Complete assembly proof of performance. Send your tute of Stand- 250-283 retails only $39.49. order in today. ards, Popular KMJ Fresno, Calif., San Joaquin Special discounts to those who want to act as RADIO BATTERIES Radio Labor- Light and Power Corp 50 -248 demonstrators. Liberal financial arrangements. 6-Volt. 100- Amperes . . $12.25 atories, Radio KMO Tacoma, Thousands sold. 6-Volt, 120-Amperes . . . . 19.25 Wash., Love Electric 6 -Volt, 140-Amperes Broadcast Lab- . . . . 15.00 oratories Co. 10 -360 Send no money to get this wonderful 5 tube AUTO BATTERIES and KNT Kukak Bay, Neutrodyne Kit. Just 6 -Volt, 11 -Plate - . $12.25 Lefax, Inc. Alaska, Walter send name and address 6 -Volt, 15 -Plate 14.25 Henrich and pay postman 011 arrival. Written money - 12 -Volt, 100 -263 7 -Plate 17.00 Solid Rubber KOA Denver, Colo., General Elec- back guarantee with each kit. Be first in your SEND NO MONEY Container tric Co. 1000 -322.4 town. Write today for kit and plan. Send for Just state battery wanted and ROB State College, N. M.. New our new catalog on other sets and parts. we will ship day order is received, Now Standard THE RADIO SHACK by Express C. O. D., subject to equipmenton all Mexico College of Agricul- your examination World Storage ture and America's Largest Radio Dealers on arrival. Mechanic Arts 500 -348.6 Dept. D19 Extra Offer: 6% discount for KOP Detroit, Mich., Detroit Police 55 Vesey Street, New York, N. Y. cash in full with order. Buy now Batteries. ge or Department and get a guaranteed battery at breakage ofjars 500 -278 60%p saving to you. , . orrottingof box. KPO San Francisco, Calif., Hale Bros. WORLD BATTERY COMPANY 500 -423 1219S.WabashAve., KPPC Pasadena, Calif., Pasadena Pres- Dept. 19 Chicago,Ill. byterian Church 50-229 Your Tires Free KQV Pittsburgh, Pa., Doubleday - a L Hill Electric Co. 500 -275 30 t omit JitatiartaralLEBEL KQW San Jose, Calif., Charles D. ` Hé 50-240 KRE Berkeley, Calif., Berkeley Daily Gazette 50 -275 ADDING MACHINE KSAC Manhattan, Kans., Kansas State VEST POCKET Agricultural College ... 500 -340.7 SIZE KSD St. Louis, Mo., Post Dispitch 500 -545.1 ADDS KTHS Hot Springs, Ark., New Ar- SUBTRACTS lington Hotel Co. 500-374.8 MULTIPLIES KTW Seattle, Wash., First Presby- DIVIDES $2so terian Church 750 -360 NEW Does Work KUO San Francisco, Calif., Exam- Ìsibie átMallMTimés. ' finer Printing Co. 150 -360 1 i FREE TRIAL -Send No Money KWG Stockton, Calif., Portable Wire- Miles cnlranteed Aayeae Cu Operate It. Guaranteed for Life less Telephone Co. 50 -360 Just write "Send me a Baby Calculator"and give KWH Los Angeles, Calif., Los your name and address. We will ship it immedi- An- Agent Users Wanted ately. all charges prepaid. On delivery pay geles Examiner 250 -360 QEE how easy it is with the MASTER SALES- postman $350. You can return it after l0 -day KYQ Honolulu, Hawaii, The MAN KIT, which I send Free, trial for full refund if the Baby Calculator Electric to make $10 to SYS AGENTS is not the greatest time and labor saver you Shop 100 -270 B day in your spare time showing MELLINGER TIRES E..rvbs.I everuaed.Thlalath tprleedpraohcal KYW Chicago, Ill.. Westinghouse at BIG SAVING to car owners. This powerful. T..arm. calculating machine made. band- éïu°.é b.é:wll Order today. Electric & Mfg. Co. 1500 -535.4 made, oversize, non-skid Cord i s guaranteed by Bond BABY CALCULATOR SALES CO. KZM Oakland, Calif., Preston for mileage half way arcund the world. cÓMMI55i Vic BIG P. O. Box 1118, Chicago, 111 Dept C D. The Allen 700 -360 Mellinger Plan starts you in business, all or part KZKZ Manila, time; no capital or experience needed. Tires shipped pre- P. I., Electrical Sup- paid on approval. Lowest wholesale prices in America. ply Co. 100 -270 If you will boost MELLINGER TIRES, I have a KZRQ Manila. P. I., Far Eastern offer give of FREE tires Freé Kit witch SAVE GASOLINE- ELIMINATE CARBON Radio (Inc.) 500 -222 temple sections. Be first to get mr free offer amazing, confidential wholensle prices and big free book. Simply send name K7.ITV Manila, P. I., F. Johnson to nearest address. B. L.MELLINUER, Pros., today INCREASE YOUR MILEAGE Elser 500 -370 MELLINGER TIRE & RUBBER WAAB Nesv Philadelphia, CO. 25 TO 40 PER CENT SAVING GUARANTEED Orleans, La., Valdemar Pa. Dept. 1931', Kansas City. M0. Jensen 100 -268 The "VAPO" Vaporizer is an unique automatic Pat- WAAC New Orleans, La., Tulane ented adjustable device which reduces the consumption University 400 -360 of gas from 25 to 40 per cent, removes and prevents WAAD Cincinnati, Ohio, Ohio Me- carbon formation in cylinders and increases power of chanics Institute the motor. Easily installed in five minutes and no 25 -360 holes to drill. Our money back guarantee entirely WAAF Chicago, Ill., Chicago Daily protects you. Distributors and agents wanted. Write Drovers Journal 200 -278 us how to receive samples. \VAAM Newark, N. J., I. R. Nelson Co. 250 -263 Sizes for Free "VAPO" SPECIALTY COMPANY WA AN ail Demoens Columbia. Mo., University of of noses. mtra- 450 North 12th St. Philadelphia, Pa. Missouri 50-254 non if desired \VAAW Omaha. Neb., Omaha Grain At11TA Exchange 500-278 fOSE ADJUSTER WA BB Harrisburg. Pa., Harrisburg The GENUINE (Patented) Sporting Goods Co 10 -266 Shapes while you sleep. Rapid. pain- \V: less and safe. The ANITA is a Gen- AGENTS WANTED \BD Dayton, Ohio, Parker High uine and most Comfortable Nose Sup- School 5 -283 porter. Absolutely GUARANTEED ANTI -MIST \VABH Sandusky. Ohio, Lake Shore Highly recommended by Guarantees Tire Co 10 Physicians. b -240 booklet. Clear Vision \NABI Bangor. Me., Bangor Railway tue's yToEle"NarWa YOU c a n quickly & Electric Co. 100 -240 build a big money- WABL Storrs, C o n n., Connecticut The 41111TR Co. making business o f Agricultural College 100 -283 WPrinlerTeb'23 655tHlg7h3St., N BEFORE-11FTER your own selling Anti - WABM Saginaw, Mich., F. E. Doherty WARKINu'J. Mist. Sells to auto Automotive & Radio Equip- owners, garage and auto sup- ment Co. 20 -261 ply stores, opticians, drug- \VABN La Crosse, Wis., Ott Radio, BE AN gists, cigar stores, railroads, Inc. 500 -244 OFFICER WABO in the U. S. Coastguard and street car companies. Anti -Mist makes glass Frost - Rochester, N. Y., Lake Avenue $1700 Up to $7.500 Yearly proof, steam -proof and weather- proof. Clear vision guar- Baptist Church (Hickson Ton get $700 yearly at the U. S. anteed In all weather; money back guarantee 1f It fails. Electric Co.) 100-278 Academy while training. You rank $50 to 5100 WEEKLY WABQ Haverford, Pa., Ensign to Captain in service. We Haverford Col- Guarantee prepare Others are doing it. Sells on sight. Anti-Mist retails at lege Radio Club 50 -261 to you in time for is for g,b oz. can -$1.50 for 8 oz. can. Send .35 for aá Academy Examinations. Age require- oz. can and full particulars of exclusive agency NOW. WABR Toledo, Ohio, S c o t t High ments 18 to 24. Write Dept. D -25 School 50-263 for free information. ANTI -MIST CHEMICAL COMPANY COASTGUARD Dept. 5 201 E. Ontario Street. Chicago, Ill. WABU Camden. N. J., Victor Talking PREPARATORY SCHOOL Machine Co. 50-226 I653 Pa. Ave., N. W. Washington. D. C.

www.americanradiohistory.com Science and Invention for d prit, 1925 1261

Power VA. AAAAAAAAAAAAAAAAAAAAAl. flAAAAAAAAAAAAAAAAAAAAAAAAAAAAA L` Call - & Wave Letters Location arid Name Length WAB \V Wooster, Ohio, College of Wooster 20 -206.8 WABX Mount Clemens, Mich. (near). Henry B. Joy 50 -254 The Printers' eArt WABY Philadelphia, Pa., John Magal- di, Jr. 50 -242 WABZ New Orleans, La., Coliseum eApplied to Typewriting! Place Baptist Church 50 -263 WAHG Richmond Hill, N. Y., A. H Grebe & Co. 500 -315.6 What the NEW C7yj'ILLIONS of typewritten letters go \VBAA West Lafayette, Ind., Purdue HAMMOND Does 1, unread today because they look so University 100 -275 Writes in any kind of type you %VBAN Paterson, N. J., Wireless uninteresting. But that can't be said of Phone Corp. 100 -244 want. \ \'BAO Decatur, Ill., James Miliikio Instantly changes from one style a Hammond -typed letter! or size to another- simply by University 100 -275 shifting gears. old words in \VBAP Fort Worth, Texas. Wortham- The new Hammond dresses up Changes letter spacing to fit vari- Publishing Co. (Star - styles they arouse Carter ous sized types. so many new and different that Telegram) 1000 -475.9 immediate attention. Today, hundreds of ex- \VBAV Columbus, Ohio, Erner & Hop- Makes use of over 50 different kins Co. 500 -293.9 languages and 140 mathemat- machine for sales ical and special characters. ecutives are using this unique \VBAX Wilkes -Barre, Pa., John H. letters, and documents whose importance Stenger, Jr., 20 Assures uniform impression by reports -256 automatic touch. WBAY New York, N. Y., Western demands unusual methods of presentation. Electric Co. 500 -492 \VBBA Newark, Ohio, Plymouth Con- gregational Church 20 -226 \VBBD Reading, Pa., Barbey Battery Service 50 -234 WBBF Atlanta, Ga., Georgia School of Technology 500 -270 \VBBG Mattapoisett, Mass., Irving Vermilya 500 -248 TYPEWRITE R WBBH Port Huron, Mich., J. Irvin; VARIABLE SPACING Bell 50-205.4 WBBL Richmond. Va., Grace Cove- CHANGEABLE TYPE nant Church 100 -283 WBBM Chicago, Ill., H. Leslie Atlass 200 -226 \VBBP Petoskey, Mich., Petoskey High What special typewriting do YOU require? School 5 & 100 -214.2 The New Hammond comes in either the catalog describing the New \VBBR Rossville, N. Y., Peoples Pul- Write today for illustrated Desk Type or Folding Portable, which has and suggesting countless ways it can be pit Assn. 500 -273 all the exclusive features of the Desk Type, Hammond, \\BBS New Orleans, La., First Bap- but weighs only 8% pounds. made to serve. tist Church 50 -252 WBBU Monmouth, Ill., Jenks Motor Hammond Typewriter Corp., 72 Brook Ave. at 132nd St., New York Sales Co. 10 -224 WBBV Johnstown, Pa., Johnstown Ra- dio Co. 5 -248 YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYVYYP WBBW Norfolk, Va., Ruffner junior 11 High School 50 -222 \VBBY Charleston. S. C., Washington Light Infantry 10 -268 \VBBZ Indianapolis, Ind., Noble B Watson 50 -227 \VBCN Chicago, Ill., Foster & McDon- nell 500 -266 \VBS Newark, N. J., D. W. Mae. Inc. 50 -360 WBT Charlotte, ceYourlatlie N. C., Southern Radio Corp. 250 -360 WBZ Springfield, Mass., Westing- house Electric & Mfg. While Co. 1500 -333.1 WCAD Canton, N. Y., St. Lawrence University 250-263 Paying \VCAE Pittsburgh, Pa., Kaufmann & Baer Co. 500 -461.3 WCAG New Orleans, La., Clyde R forIt Randall 50 -268 Ni \VCAH Columbus, Ohio, Entrekin exila Electric Co. 200 -266 charle Now You Can Get This \VCAJ for University Place, Neb.. Ne- all 11' x 312 " Quick Change Gear braska Wesleyan University 500 -280 equip- melt \VCAK Houston, Texas, Alfred P shown Daniel 10 -263 under SOUTH BEND WCAL Northfield, Minn., St. Olaf Lathe. SCRTTEW College 500 -336.9 OS' x CUING LATHE WCAO Baltimore, Md., Sanders & Stayman Co. 50 -275 WCAP Washington, D. C., Chesa- -for ONLY $284 Easy payments if desired peake & Potomac Telephone Co. 500 -468.5 11s c i. nlr chance to get a brand new latest improved South Bend Lathe on convenient terms. We ship Lathe upon receipt of first payment, allow 30 WCAR San Antonio, Texas, Southern for it. In this Radio Corporation Texas 100 SOUTH BENZ) days' trial, and you have the use of the Lathe while paying of -263 We make this liberal offer on any South Bend \ \CAS Minneapolis, Minn., William Lathes embody 32 way it helps earn its own cost. m aj o r improvements Lathe. 31,000 in use in U. S. and 64 Foreign Countries. Hood Dunwoody Industrial Shows 96 styles in all sizes, from small Bench Institute 100 -280 made within the last CATALOG FREE Lathe to largest Factory Lathe. Compare \VCAT Rapid City, S. D., South Da- 2 years. Unsurpassed our prices with what others ask, and remember every South Bend Lathe carries kota State School of Mines 50 -240 in accuracy and clii- our liberal guarantee and 30 day trial offer. Send for Catalog today. \VCAU Philadelphia, Pa., Durham & ciency. Co. 500 39.5 EBend, Madison S,t. -278 South WCAV Little Rock, Ark., J. C. Dice South Bend Lathe Works, S. A Electric Co. 10 -263 \VCAX Burlington, Vt., University of LATEST WHOLESALE Vermont 100 -360 WCAY Milwaukee, Wis., Hotel Ant- RADIO CATALOG lers, Milwaukee C i v i c Simply send name Broadcasting Assn. 250 -266 Begin Today -Write for Si y Nnf:l- BOOK .011 Carthage, Ill., can make a good penman of you at homo during \VCAZ Carthage College 50 -246 pare time. Write tor my FREE BOOK, "How TODAY for big WCBA Allentown, Pa., Charles W. To Become Good Penman:. It contains epeci- REE 48 - page catalog Heimach, Camegraph Repair a i tells how others mastered penman- T!- \ hip by the Tamblen . Your name win f latest radio goods at Wholesale. Shop 10 -254 card Fill WCBC Ann Arbor. Mich., J stemu to pay postage. nWrite today for book. ive dealers and agents wanted. University F.W.TAMBLYN, 424 eideaeld {.,Kenna City, U.S.A. of Michigan 200 -229 STANDARD RADIO CO., 112 East 13th, Kansas City, Mo. WCBD Zion, Ill., Wilbur G. Voliva.. 500 -344.6 WCBE New Orleans, La., Uhalt & Brothers Radio Co. 5 -263 Insure your copy reaching you each month. Subscribe to Science Invention -$2.50 a year. Publishing Co., 53 Park Place, N. Y. C. (Confirmed ou page 1263) Experimenter

www.americanradiohistory.com 1262 Science and Invention for .ol pril, 1925 Complete List of Titles in the E. I. Co. Books All About Radio Parts Everyone who constructs a radio set should know the simple fundamentals of the various parts of his set. The E. I. Company has set these forth in a compact little book that is valuable at all times. Book No. 8 -Price 25c History and Operation of the Vacuum Tube The Vacuum Tube is a marvelous piece of apparatus. A short study of it as given in this hook gives you the principle on which every Vacuum Tube Radio Receiver operates. Book No. 9 -Price 25c The Neutrodyne -All About It Everybody knows the famous Neutrodync hookup. One of the finest Radio Receivers in use today. This 54 -page E. I. Company book gives an explanation of every detail of the Neutrodyne and how it all works. Book No. 10 -Price 25c How Radio is Received The simplest and yet most complete Radio Guide Book for any amateur broadcast listener. In print only two weeks. fresh from the press. Book No. 11 -Price 25c How to Locate Troubles in Your Radio Set Anyone with this handy book as a guide can repair and keep in order his own radio set. Covers every detail of the modern radio sets and tells how to locate and repair any trouble. Book No. 12-Price 25c Radio Reflex Receivers Just off the press. Hookups galore on the finest and most up -to -date reflex circuits in use today. Diagrams and descriptions on every modern reflex. Book No. 13 -Price 25c Tips for the Radio Amateur Constructor Many men fail in building their Radio seta because of some trivial error that could easily have been corrected before it was too late. The E. I. Company has compiled a bock that will help you avoid all the common pitfalls while building your Radio seta. i Book No. 1 -Price 25c E E Ca. How to Make PRACTICAL Radio wEwronn clrr Receiving Sets The man who wants to build only those PRACTICAL Radio Sets that are guaranteed to give good results when properly constructed will need this book. Gives the principal successful hookups of practical Radio Construction. Book No. 2 -Price 25c Any radio receiver will give better Radio Questions Answered Question No. 1 -What is Radio? This is the nature of the questions that this book o answers. Then it answers questions on all results if you learn more about it the principal parts of a Radio Receiver. It is a handy book to keep in your Radio File. ANY radio receiver gives better results in the hands of an experienced Book No. 3 -Price 25e radio man. The reason for this lies not in their intimate knowledge of radio parts but Radio Frequency Amplification rather in their fundamental knowledge of how the receiver operates. Distance lends enchantment-and it's the Radio Frequency Amplification that brings The radio books of the E. I. Company are written with this sole object in view in the distance on your Radio Receiver. If to give the average broadcast listener the fundamental knowledge that will enable you contemplate adding any Radio Fre- quency to your set you will want this book him to understand the care and operation of the receiver he buys or builds. at your side. Some of the E. I. books cover only the care and operation of general radio re- Book No. 4 -Price 25c ceivers, others cover the construction and operation of specific types of receivers, How to Tune Your Radio Set while a third class cover that intimate, general knowledge of radio transmitting and Don't struggle in the dark, looking for sta- receiving that everyone should know. tions -here is an inexpensive book that gives you detailed instructions on Just how ' Glance over the titles of the books listed on this page. They are sold every- to handle your Radio set. You will be sur- where. Or, if you wish you can obtain them us. prised at the increased results that can be direct from obtained through proper tuning. Book No. 6 -Price 25e PAIL E. I. Co. Books are 25c. Each - 100 Radio Hookups Published by No better book for your work bench. Gives diagrams. hook -ups and details on Radio Hook-ups galore. One of the most complete hook -up books published. Authentic and E. L Company, Inc. up -to -date in every respect Third edition now ready. Book No. 7-Price 25c ff E. I. Co. Books are sold throughout the country by all Radio and News Dealers Sole Distributors If Your Dealer Cannot Supply You, Write Direct 233 Fulton Street New York, N. Y.

www.americanradiohistory.com Science and Invention for April, 1925 1263 ,,nnmmnw estesa ,,,a rrrt BUILDING TRADES. Radio IzToadc zt NEED TRAINED MEN E. (Continued frone page 1261) Thousands of good positions Treotendous, big- paying opportunities at good salaries are open fir ambitious men in Mod- ern Photography. This is the picture THE building trades age. Magazine and newspaper publish- Power are still booming. ers buy thousands of photographs each Call & Wave year. Every manufacturer sends out Letters Location and Natte Length Trained men are in de- high priced pictures of his products. mand at good salaries. Every hens wants portraits. Photog- WCBG Pascagoula, Miss. (portable), raphy is a business running into Howard S. Williams 10-268 Government experts millions of dollars each year. WCBH Oxford, Miss. '(near), Univer- Got $100 for And there is a great shortage of estimate that Flood Pictures trained photographers. sity of Mississippi 10-242 billions of "I took pictures WCBI Bemis, Tenn., Nicoll, Duncan $3,000 to $10,000 a Year dollars will of a flood a n d Earn & Rush 150 -240 . sold them for Hundreds of men are earning be spent for , WCBJ Jennings, La J. C. Mans 10-244 $100. I have big money and establishing their been able to buy own businesses. Even during WCBK St. Petersburg, Fla., E. Rich- construction my house and lot while training, you ard Hall 500 this year. the sale of spare time, -266 from can make $75 a week easily - WCBL Houlton, Me., Northern Radio pictures." no matter where you live! Today the most vital need of this great C. M. Cole. Mfg. Co. 50-280 building program is men -trained men Washington. Amazing New Easy Method WCBM Baltimore, Md., Hotel Chateau - S97 in 2 Days! men who can step right in and do the skilled "I made $285 in I show you at home, how to do (Charles Schwartz) 50 -229 December. Went the kind of work turned out by NV 030 Memphis, Tenn., Radio Shop, work that building construction requires. out two days last the big studios in New York Inc. 20 -250 There is a simple, easy, practical way week o n home and Chicago! I show you how to matte big money within 30 days! W CBQ Nashville, Tenn., First Baptist posi- portrait work Church 100 by which you can prepare for abetter and made $97." C. M. Cole bought a home with -236 do it A. G. Hughes, money he had made Olsen only WCBR Providence, R. I. (portable), tion, at a bigger salary. You can Kentucky. half way through his training. Charles H. Messter 30-246 right at home, in spare time, no matter So well do I know what I can WCBT Worchester, Mass., Clark Uni- where you live, through the International do for you that I guarantee versity 250 under bond to return every cent of your tuition if you -238 Correspondence Schools. are not thoroughly satisfied. WCBU Arnold, Pa., Arnold Wireless Supply Co. (F. J. Ambrose) 50 -254 eIjA recent investigation of 13,928 students en- Professional View Camera FREE! WCBV Tullahoma, Tenn., Tullahoma rolled in I. C. S. Building Trades Courses Camera Offer Write at once for Free Radio Club 10-220 showed that 1921 had become Architects ; 246 -I give you, free, a splendid pro- Ga., fessional view camera. You will be WCBW Macon, George P. Ran- had become Designers; 494 had become Chief astonished and delighted. This offer kin, Jr., and Mitland Solo- Draftsmen; 2827 had become Draftsmen; 1845 open for short time only - so act man 10-226 had become Contractors; 211 had quick! No obligation. WCBY Buck Hill Falls, Pa., Forks Electrical Shop 10-268 become Assistant Foremen; 4030 INTERNATIONAL STUDIOS. Inc. had become Foremen; 2354 had Dept. 1424 WCBZ Chicago Heights, Ill., Coppo- telli Bros. Music House 50 become Superintendents. 3601 Michigan Ave., Chicago, U.S.A. -248 WCCO Minneapolis, Minn Washburn - You, too, can have the position Crosby Co. 500 -416.4 you want in the work you like WCEE Elgin, Ill., Charles E. Erbstein . 1000-536 best; an income that will give WCK St. Louis, :Sto.. Stix -Baer & you and your family the home, Fuller Dry Goods Co. 100 -273 WCM Austin, Tex., Texas Markets the comforts, the luxuries you and Warehouse Department 250 -268 would like them to have. WCX Detroit, Mich., Detroit Free Mail the Coupon for Press 500 -516.9 WDAF, Tampa, Fla., Tampa Daily Free Booklet Times 250-273 Prices Smashed! WDAF Kansas City, Mo., Kansas City 'TEAR OUT NINE ate.w.. a Quality Not Sacrificed Star 500 -365.6 WDAG Amarilla, Texas, J. Laurance INTERNATIONAL CORRESPONDENCE SCHOOLS Here is real battery BOX 6203 -D SCRANTON, PA. Martin - 100 -263 quality, guaranteed to you, at Explain. without obligating me, how I can qualify for the prices that will astound the en- WDAH El Paso, Texas, Trinity Meth- position, in subject, before which I mark X. odist Church (South) 50 or the tire battery- buying public. Order -268 ARCHITECT - Navigation direct from factory. Put the Dealer's W DAR Philadelphia, Pa., Lit Broth- Architectural Draftsman SALESMANSHIP Profit in your own pocket. You actually save ers 500 -394.5 Architects' Blue Prints ADVERTISING much more than half, and so that you can be WDAS Worcester, Mass., Sam Waite's Contractor and Builder Window Trimmer performance, we Building Foreman Show Card and Glen Painting, convinced of true quality and Radio Shop 10-360 Concrete Builder BUSINESS MANAGEMENT give a WDAY Fargo, N. D., Radio Equipment Structural Engineer Private Secretary Written Two -Year Guarantee Corporation 50-244 Structural Draftsman Business Correspondent Hereisyourprotection! Noneedtotakeachance. WDBB Taunton, Mass., A. H. Waite 'Malabar and Steam Fitter BOOKKEEPER the price is the lowest Heating and Veatilationl Stenographer and Typist Our batteryia right -and & Co. 10-229 Plumbing Inspector Higher Accounting evermade. Convince yourself. Read the prices! WDBC Lancaster, Pa., Kirk, Johnson Foreman Plumber COMMERCIAL LAW' Special 2 -Volt Radio Storage Battery. $3.75 & Co. 50-258 Sheet Metal Worker Common School Sableats Special 4 -Volt Radio Storage Battery, 6.00 WDBD Martinsburg, W. Herman CIVIL ENGINEER Mathematics 6 -Volt, 60 Amp. Radio Storage Battery, 7.00 Va., Surveying and Mapping GOOD ENGLISHI 6 -Volt, 80 Amo. Radio Storage Battery, 8.00 E. Burns 5 -268 ELECTRICAL ENGINEER ILLUSTRATING 6 -Volt, 100 Amp. Radio Storage Battery, 9.50 WDBE Atlanta, Ga., Gilham- Schoen Electric Lighting and Rya Railway Mail Clerk 120 Amo. Radio Storage Battery,11.50 6 -Volt, Battery,13.00 Electric Co. 100-278 Electric Wiring CIVIL SERVICE 6 Volt, 140 Amp. Radio Storage WDBF Youngstown, Ohio, Robert G. Telegraph Engineer Mining Engineer Simply send name Telephone Work Gas Engine Operating We ask for no deposit. Phillips 50-246 MECHANICAL ENGINEER STATIONARY ENGINEER and address and style wanted. Battery will WDBH Worcester, Mass., C. T. Shear Mechanical Draftsman Teethe Overseer or Supt. be shipped the day we receive your order Co. 100 -268 Toolmaker TRAFFIC MANAGER Express C. O. D., subject to your WDBI St. Petersburg, Fla., Radio Machine Shop Practice AUTOMOBILES 9paobh examination on arrival. Our CHEMIST AGRICULTURE French Specialty Co. 20 -226 Pharmacy Poultry Raising (]RADIO guarantee accompanies WDBJ Roanoke, Va., Richardson -Way- each battery. Weallow5% land Electrical Corporation 50 Name discount for cash in full -229 3.6 -24 with order. You cannot WDBN Bangor, Me., Maine Electric Occupation Business your Light & Power Co. 5 -252 as Address lose! Act quick. Send WDBO Winter Park, Fla., Rollins Col- Street order today-NOW, lege 50-240 and No. WDBP Superior, Wis., Superior State City State Arrow Battery Co. Normal School 50-261 Canadians may send this coupon to Internaiionai Corre- 1421 South Wabash Ave. WDBQ Salem, N. J., Morton Radio spondence Sohoola Canadian, Limited, fontreal, Canada Chicago, IN. Supply Co. 50-234 Dept. 9 WDBR Boston, Mass., Tremont Tem- ple Baptist Church 100 -256 Agents Wanted! DEAFNESS IS _ MISERYI WDBS Dayton, Ohio, S. M. K. Radio Salesmen- Distributors I know because I was Deaf and had Head Noised Corp. 5 -275 attachment for over 30 years. My invisible Antiseptic Eat to use and introduce and stopped Head WDBT Hattiesburg, Miss., Taylor's that makes Fords run on 94% Drums restored my hearing air, THERMOSTAT on ex- Noises, and will do It for you. They are Tiny Book Store 10-236 turns Megaphones. Cannot be seen when worn. Effec- WDBW Columbia, Tenn., The Radio haust automatically is caused by Catarrh or by down needle valve as engine tive when Deafness Den 20-263 warms exactly as Ford Perforàted. Partially or Wholly Destroyed Naturall hand. Drums. Easy to put in, oaey to take out. Are WDBX New York, N. Y., Otto Baur 5 -233 Manual says do by *0 "Unseen Comforts." Inexpensive. Write for WDBY Chicago, Ill., North Shore Con- of how recur.' Blancke Auto Thermo Booklet and my sworn statement I gregational Church 500 -258 An Automatic Carburetor Control Bred my hearing. WDBZ Kingston, N. Y., Boy Scouts Makes Fords start A. O. LEONARD of America County summer-saves gas ldanol .cta -u -- New York (Ulster repair one -half- reduces carbon Suite 369, 70 5th Avenue City Council) 5 -233 formation one -half. Sells on sight to Ford owner as easily as giving WDM Washington, D. C., Church of imhvery a $100 hill, because It eaves $100 the Covenant 50 -234 every 10,000 miles. Cadillac now uses The Midget as standard equipment thermostat c WDZ Tuscola, Ill., James L. Bush 10-100 carburetor control under Blanche "Five -in -One" Slide Rule Mich., Police Building, license. You can make Big Money e Sling a combination Mannheim, Polymet- WEAA Flint, this wonderful proven device. Exiler eats not neces '.ary. Blanche risic, Los -Log, Binary, Add and Sub- Frank D. Fallain 50-234 plan will start you without capital in a bueinese of your own that taunt Slide Rule, It will instantly add, New York. N. Y. American makes you from $250 to $2,000 a month profit. ubtraet, multiply and divide any com- WEAF Write for free circulars Nowt bination of whole numbers, fractions, Telep. & Teleg. Co. 2000 -491.5 mixed numbers and decimals. Gives every root and er, also Loge, Sines WEAH Wichita. Kans., Wichita Board A. C. Blanche & Co. De 112k Chicago and Tangents. Made of aluminum with of Trade 50-268 scales on white celluloid. Sire 4 in. Ap- copy reaching you each month. Sub- proved and adopted by coll.gea. Price WEAI Ithaca, N. Y., Cornell Univer- Insure your with inatrostione. 41.50. Leather eerie sity 500 -254 scribe to SCIENCE & INVENTION -$2.50 a 50c extra. Sent C.O.D if desired. Cat- 53 Pl., alogue ON SLIDE RULE WEAJ Vermilion. S. Dak., University year. Experimenter Publishing Co., Park (Patented 1 -17 221 alo e Mich.L of South Dakota 100 -252 N. Y. C.

www.americanradiohistory.com 1264 Science and Invention for April, 1925

Power Call & Wave Letters Location and Naine Length \VEAM North Plainfield, N. J., Bor- ough of North Plainfield...250 -261 WEAN Providence, R. I., Shepard Co. 100 -273 \YEAO Columbus, Ohio, Ohio State University 500 -293.9 WEAP Mobile, Ala., Mobile Radio Co. 100 -263 \VEAU Sioux City, Iowa, Davidson Bros. Co. 100 -275 WEAY Houston, Tex., Iris Theatre 500 -360 \VEB St. Louis, Mo., Benson Radio Co. 100 -273 Poor Yesterday \VEBA Highland Park, N, J., The Electric Shop 15 -233 \VEBC Superior, Wis., Walter C Bridges 10-244 WEBD Anderson, Ind., Electrical YESTERDAY'S alarm clock was a dash of Equipment & Service Co 10-246 WEBE Cambridge, Ohio, Roy W. Wal- cold water thrown in the face. Yesterday ler 10 -243 WEBH Chicago, Ill., Edgewater Beach never looked through a window glass or drove Hotel Co. 1000-370.2 \VEBI Salisbury, Md., Waltér Gib- a Ford sedan. Yesterday could have stood all bons 15-242 \VEBJ New York, N. Y., Third day pushing buttons, turning on faucets, shov- Avenue Ry. Co. 500 -273 WEBK Grand Rapids, Mich., Grand eling in coal -and have never got a bit of hot Rapids Radio Co. 20-242 WEBL United States, R. C. A 100 -226 water, electric light, or radiator heat. Yester- WEBO Hamilton, Ohio, Harry W Fahrlander 5-252 day mined for its salt, tilled for its bread, WEBP New Orleans, La., E. Budd Peddicord \VER) 0 -28 t sheared and spun for its clothes. Yesterday Harrisburg, Ill., Tate Radio Co. 15 0 -236 \VEBR Buffalo, N. Y., H. H. Howell 15 -240 lived to itself and died of diseases unknown. \VEST Dayton, Ohio, Dayton Cooper- ative Industrial High School 5 -256 WEBW Beloit, Wis., Beloit College 500 -268 Then was born To -day. WEBX Nashville, Tenn., J. E. Cain, Jr 50-263 \VEBY Roslindale, Mass., Hobart Ra- dio Co. 10 -226 To -day gives you convenience, ease, speed. WEBZ Savannah, Ga., Savannah Radio Corp. 5 -234 Advertised products have brought them. If \\'EEI Boston, Mass., Edison Electric Illuminating Co. of Boston 500 -475.9 you read the advertisements, you can gain more WEMC Berrien Springs, Mich., Em- manual Missionary College 500 -286 convenience, ease, speed. They tell of the new WEV Houston, Tex.. Hurlburt -Still Electrical Co. 100 -263 and better taking place of the old. They tell WEW St. Louis, Mo., St. Louis Uni- versity 100 -280 of the best means to secure them. They help WFAA Dallas, Tex., Dallas News & Dallas Journal 500 -475.9 you get what you want and know what you are \VFAM St. Cloud, Minn., Times Pub- lishing Co. 10-273 getting. They assure you satisfaction. WEAN Hutchinson, Minn., Hutchinson Electric Service Co. 100 -286 \VFAV Lincoln, Nebr., University of Why make a Yesterday out of your life? Nebraska 250-275 WFBB Eureka. Ill.. Eureka College 50 -240 Read the advertisements. Live To -day. WFBC Knoxville, Tenn., First Baptist Church 50 -250 . WFBD Phihdelphia. Pa., Gethsemane Baptist Church 5 -234 WFBE Seymour, Ind., John Van de Walle 20-226 WFBG Altoona, Pa., William F. Gable Co. 100 -278 WFBH New York. N. Y., Concourse Radio Corp. 500-273 WFBI Camden, N. J., Galvin Radio Supply Co. 100 -236 You can't keep entirely up -to -date WFBJ Collegeville, Minn., St. John's University 50 -236 without reading advertising WFBK Hanover, N. H., Dartmouth College 100 -256 WFBL Syracuse, N. Y., Onondaga Hotel 100 -253 WFBM Indianapolis, Ind., Merchants Heat & Light Co. 250 -263 WFBN Bridgewater, Mass., Radio Sales & Service Co 200 -226 \VFBQ Raleigh, N. C., Wynne Radio Co. 50 -252 \VFBR Baltimore, Md.. Fifth Infan- try, Maryland, N. G. 100 -254 WFBT Pitman, N. J.. Gloucester County Civic League 50 -231 WFBY Fort Benjamin Harrison, Tnd , U. S. Army, Fifth Corps Area 100 -258 PERSONAL STATIONERY F'or Your Boa WFBZ Galesburg, Ill., Knox College 10-254 WFI Philadelphia, Pa., Strawbridge 200 SHEETS and 01c Eonrude's New & Clothier 500-394.5 ( I Quick Detachable WGAL Lancaster. Pa., Lancaster Elec 100 ENVELOPES ROWBOAT MOTOR tric Supply & Construction i ®® Easily carried. Quickly attached to any Co. 10-248 Printed your Name and Address boat (without tools). Drives boat any WGAQ with speed, 2 to 10 miles perbour. No rowing, Shreveport, La., Youree Hotel 150 -263 Clear, white bond paper, with envelopes to match. no work, no bother. WGAZ South Bend, Ind., South Bend Your name and address printed in beautiful, rich Fast -Light- Powerful Tribune 250 -275 blue ink, on both paper and envelopes, and sent to Easy to Carry WGBA Baltimore, Md., Jones Electric you postpaid for only $1.00. (West of Mississippi & Radio Mfg. Co. 50 -25 river and outside of U. S. $1.10.) If inconvenient crexclusivebWite nw WGBB Freeport, N. Y., Harry H. Car- Caaag Poe iodaFy.s to send the money, we will ship C.O.D. Money re- man 100-244 turned if you are not more than satisfied. Order Elto Outboard Motor Co. WGBC Memphis, Tenn., First Baptist Manufacturer's Home Bldg. Church 10-266 today. Write name and address plainly. e- Deet,48 AGENTS MAKE BIG MONEY taking orders for M i Iwaukee. WGBF Evansville, Ind., Finke Furni- us. Write us today for nor agent's proposition. Wis. ture Co. 50-217.3 WGBG Thrifton, Va., Breitenbach's ELITE STATIONERY COMPANY Radio Shop 100-226 5030 Main Street Smethport, Pa. The Motor that Starts with aTOuch W GBS New York, N. Y., Gimbel ar® Brothers 1000 -315.6 copy reaching you WGBT Greenville. S. C., Furman Insure your each month. Subscribe to Science & Inven. University 15-236 tion -$2.50 a year. Experimenter Publishing Co., 53 Park Place, N. Y. C. WGI Medford Hillside, Mass.. Amer- i ican Radio & Research Corp. 100 -360

www.americanradiohistory.com 1265 St'irJJre and Invention for ilpril, 1925 Power Call & Wave Build Your Letters Location and Name Length ,, \VGL Philadelphia, Pa., Thomas F. J Howlett - 500 -360 Own WGN Chicago, Ill., The Tribune (Drake Hotel - Whitestone Co.) 1000-370.2 WGR Buffalo, N. Y., Federal Telep. LOW LOSS Mfg. Co. 750 -319 WGY Schenectady, N. Y., General Electric Co. 1500-379.5 WHAA Iowa City, Iowa, State Univer- sity of Iowa 500 -483.6 RECEIVER WHAD Milwaukee, Wis., Marquette University 500 -275 'TOE MO CONSTR000RSENIEf-M11NIN6Y0UWOwN - WHAG Cincinnati, Ohio, University of No.I j Cincinnati 100 -233 Vow to make WHAM Rochester, N. Y., University of Rochester 100 -278 SS,..ReCe;u WHAR Atlantic City, N. J., Seaside ALOW r Hotel 100 -275 WHAS Louisville, Ky., Courier- Journal & Louisville Times 500 -399.8 MACHINE SHOP WHAV Wilmington, Del., Wilmington Electrical Specialty Co..... 100 -266 WHAZ Troy, N. Y., Rennselaer Poly- technic Institute 500 -379.5 HANDBOOK "5 WHB Kansas City, Mo., Sweeney mr Constad Co.lnc j1.101F LOSS School Co. 500 -365.6 Awonderful book for machinists, WI-1K Cleveland, Ohio, Radiovox Co. 100 -283 WEIN New York, N. Y., George toolmakers and shop men Schubel 500 -361.2 A Simplified Pattern WHO Des Moines, Iowa, Bankers 335 Pages -282 Illustrations Life Co. 500 -526 for the Construction WIAC Galveston, Tex., Galveston Tri- Price only bune 100 -360 THIS I. C. S. MACHINE SHOP of this WIAD Philadelphia, Pa., Howard R HANDBOOK IS a wonderful Miller 100 -254 bargain at $1. Contains more Famous Receiver WIAK Omaha, Nebr., Journal- Stock- common sense, practical infor- man Co. 250 -278 other book of Just off the press! A new pattern WIK McKeesport, Pa., K. & L. Elec- mation than any on the standard, high efficiency LOW tric Co. 100 -234 its kind ever published. Pocket LOSS receiver embodying every not- ara WIP Philadelphia, Pa., Gimbel Broth- size. 335 pages. 282 illustra- able advance in this type of receiver. ers 500 -508.2 tions. A book that you will find The blueprint of the wiring diagram D WJAB Lincoln, Nebr., American Elec- incorporates a new Idea that simpli- tric Co- 100 -229 invaluable in your daily work. Will help fies radio receiver building. The wir- WJAD Waco, 'l'ex., Jackson's Radio you get a better job and a bigger sala:y. ing of each circuit is shown in a Engineering Laboratories 500 -352.7 separate color, thus: GREEN for the \VJAG Norfolk, Nebr., Norfolk Daily Contents aerial circuit, YELLOW for the low News 250 -270 Useful tables, mensuration, trigonometry, proper. potential or ground. RED for the WJAK Greentown, Ind., Clifford L. ties of materials, drilling, reaming, tapping and plate and "B" Battery and WHITE White 50 -254 threading, lathe work, threads and thread cutting, for the grid circuit. NJ AM Cedar Rapids, Iowa, D. M. Per- measuring and testing, milling -machine work, in- key work, gearing, Each pattern contains two extra ham 20 -268 dexing, helixes and spirals, large blueprints size 14x19 inches. WJAN Peoria, Ill., Peoria Star 100 -273 planer work, shaper work, Blotter work, broaching, in four WJAR Providence, R. I., The Outlet grinding and polishing and lapping, jigs and fix- giving special wiring diagram tures, punch and press work, die casting, gauges, colors, a panel layout and a complete Co. 500 -305.9 in Pittsburgh, Pa., Pittsburgh Ra- micrometers and vernier instruments, lubricants, 16 page booklet. All is enclosed WJAS indicators, metals, heat treatment, heavy color folder size dio Supply House 500 -275 temperature a handsome Trust chilled iron, welding and brazing and soldering, 9x12 inches. \VJAX Cleveland, Ohio, Union coaling and protecting, filing, sock estimating, Co. 500 -390 Chicago, chipping, riveting, pipe bending, laying out work, WJAZ Zenith Radio Corp., blue prints, belting, pulleys and shafting, knob PRICE 50c Il I, 20 -268 WJD Granville, Ohio, Denison Uni- and hitches, springs and miscellaneous shop hints. SOLD BY ALL RADIO AND versity 10 -217.3 Just mail this advertisement with a dollar bill and NEWS DEALERS WJJD Mooseheart, Ill., Supreme your name and address, and this 335 -page I. C. S. Lodge, Loyal Order of MACHINE SHOP HANDBOOK Or any of the other The Consrad Company Moose 500 -302.8 I. C. S. Handbooks that you want will come to you WJY New York, N. Y., R. C. A 750 -405.2 by return mail. Money back if not satisfied. 233 Fulton S'_reet WJZ New York, N. Y., R. C. A 500 -454.3 New York, N. Y. WKAA Cedar Rapids, Iowa, H. F. r INTERNATIONAL CORRESPONDENCE SCHOOLS, Paar 50 -278 1 Box 6208 -D Scranton, Penna. WKAD East Providence, R. I., Charles 1 I enclose E for which send me, post -paid. the I Looff (Crescent Park) 20 -240 1 Handbooks marked X, at $1 each. It is understood that if I am not entirely satisfied I may return any 1 \VKAF Wichita Falls, Tex., W. S. get my money Co. 100 I or all of them within live days and Radio Supply -360 l back. WKAN Montgomery, Ala., United Bat- D MACHINE SHOP HANDBOOK tery Service Co. 15 -226 ['Automobile Handbook D8aleaman's Handbook Handbook "RADIO'Sonsr FOREMOST PUBLISHERS" WK AP Cranston, R. L. Dutee W. Flint 50-360 1 Electrical Handbook Advertising WKAQ San Juan, P. R., Radio Corp. Chemistry Handbook ®Bookkeeper's Handbook Porto Rico 500 -340.7 l Pharmacy Handbook Civil Engineer's of I ['Traffic Handbook Handbook WKAR East Lansing, Mich., Michigan Building Trades Handbook QSteam Engineer's Agricultural College . 500 -285.5 1 Radio Handbook Handbook WKAV Laconia, N. H., Laconia Radio Club 50 -254 Name TESTS SHOW FORD WKBF Cranston, R. I.. Dutee W. Flint 500 -286 1 WRY Oklahoma, Okla., WRY Radio I Address 60 MILES Shop 100 -360 t. - J CAN RUN WLAL Tulsa, Okla., Naylor Electrical Co. 100 -360 ON GALLON OF GAS WLAP Louisville, K_y., W. V. Jordan 20 -286 WLAX Greencastle. Ind., Greencastle The amazing fact that a Ford can run 60 Community Broadcasting miles on a gallon of gasoline was recently Station 10 -231 Minn., University brought to light thru WLB Minneapolis. The PICTURE MAGAZIvE of Minnesota 5 -278 Art, Nature- The Oody test s conducted by WLBL Stevens Point, Wis., Wisconsin Beautiful, Mind Inteltec- en- Markets 500 - JAI. foal. Soul Intuitional, Ani- America's foremost Department of -278 mals, Birds, Art Prints. gineers. Great strides WLS Chicago, Ill., Sears, Roebuck & ash contests and lessons. Co. 500 -344.6 criticisms cartoons and comics. Pro- have already been made WLW Cincinnati. Ohio, Crosley Ra- CUT claims The Invisible Brotherhood. in this direction by the 1000 THIS r'an't describe-'-you must see It. Send dio Corp. -422.3 OUTS. NOW, only S1 for a mo. trial soh. recent invention of a WMAC Cazenovia. N. Y., Clive B. O. K. or refund. No free samples. Meredith 100 -275 A n'l' rd 1.1I'F:. Deft. l ßi ICalamas00. Mleh.e simple attachment WMAF Dartmouth. Mass., Round Hills which can be installed Radio Corp. 100 -500 -360 in a few minutes with- WMAH Lincoln, Nebr., General Supply to 100 -254 out any alteration WMAK Lockport, N. Y., Norton Lab- motor. A. C. Winter - oratories 500 -266 burn made 41.4 miles WMAN Columbus, Ohio. First Baptist 50 on 1 gallon of gasoline Church (W. F.. Heskett) -278 B. O. Weeks, WMAO Chicago, Ill., Chicago Daily after this device was attached. 500 -447.5 wants agents and News Wonderful, new device, guides your hand; corn cts famous aviator and inventor, WMAY St. Louis, Mo., Kingshighway your writing in few days. Big improvement in three will send sample for trial. Write him today at Presbyterian Church .... 100 -280 hours. No failures. Complete outline FREE. 426 -782 Eleventh St., Milwaukee. Wis. -Adv. WMAZ Macon, Ga.. Mercer University 100 -261 Write C. J. Dement, Dept. 44 St. Louie, Mo.

www.americanradiohistory.com 1266 Science and Invention for April, 1925 Power Call & Wave Letters Location and Name Length FREE t WMC Memphis. Tenn., "Commercial Tes Appeal" 500 -499.7 a' p. I \V\1H Cincinnati. Ohio, Ainsworth - a 1_.11; `1 Gates Radio Co. 750 -422.3 S_ / s lbwho c a4ábÿoúi`4u \VM1U Washington, D. C., Doubleday - o eh Less°t twg 1 V °q45. tread TosutDraf Hill Electric Co. 100 -261 cl'pt t . `1 THE RADIO. Ad° .' WNAC Boston, Mass., Shepard Stores 100-280.2 óuil$1 ...... WNAD Norman, Okla., University of page l°cIttFacts ...... Oklahoma 100 -254 INSTRUCTOR Nats...... Sts \VNAL Omaha, Nebr Omaha Central HANDBOOK EDITION OF ...... 't High School 20 -258 THE RADIO READING COURSE 1 Address ...... ï i WNAP Springfield, Ohio, Wittenberg College 100 -245 city' Offered WNAR Butler, Mo., First Christian ï-' Church Associsfs 20 -231 EdiforbAdvisor by a famous WNAT Philadelphia, Pa., Leming PROF.J.H.MORECROFT Brothers 100-250 Di COIYMaIA UNIvaaCITY College of Engineering WNAX Yankton, S. Dale.. Dakota Ra- PIAIR dio Apparatus Co. 100 -24.1 Here is an opportunity to prove your WNJ Newark, N. J., Radio Shop of fitness Newark 100 -233 and liking for one of Indus- WNYC New York, N. Y., City of try's highest -paid professions.Voca- New York 1000 -526 WOAC Lima, Ohio, Page Organ Co 50 -266 tional guidance of the highest order WOAE Fremont, Nebr., Midland Col- free test lesson in lege 15 -280 -a Drafting. WOAF Tyler. Tex., Tyler Commercial College 10 -360 PRICE 'loo WORT San Antonio, Tex.. Southern Equipment Co. 500 -394.5 DRAFTING WOAJ Parsons. Kans., Ervins Elec- trical Co. 15 -258 Short WORN Lawrenceburg, Tenn., James HOME STUDYcos.rse D. Vaughn 200 -282.8 A Free Trial Home Study Lesson sent you WO.1R Kenosha. Wis., Henry P. A Lundskow 50-229 Solid without obligation. Before you enroll we WOAV Erie, Pa., Pennsylvania Na- want you to know what drafting is like .. . tional Guard, 112th Infantry 50 -242 Foundation for how we teach by mail ... and whether you WOA\V Omaha, Nebr., Woodmen of will like this fascinating, well -paid profession. the World 500 -526 WOAX Trenton. N. J., Franklyn J. Your Radio Wolff 500 -'40 40 -page Book of Facts, FREE WOC Davenport, Iowa, Palmer Tells School of Chironractic .. 500 -483.6 Work .1.111M1, you all about drafting and our short, WOCL Jamestown, N. Y., Hotel James- Here's a radio book intensive drafting courses. What prominent town 15 -275 that gives you men say where WOI Ames, Iowa, the complete theory, design, con ... draftsmen are employed Iowa State Col- struction, operation and maintenance their salaries . .. their opportunities ... lege 500 -360 of radio receiving apparatus. how . .. and why many of our students have in- WOO Philadelphia, Pa., John Wana- ... maker 500 The book is divided into five sec- creased their salaries even be- -508.2 tions each completing a separate divi- fore finishing their courses. WOQ Kansas City. 'Mo.. Unity sion of School of Christianity 500 -278 radio receiving information WOR to that the reader can more easily $35 to $100 per Ne,Iarb, N. J., L. Bamberger use the book for handy Week & Co. 500 -405.2 reference. Everything today . . . from WORD Batavia, Ill., Peoples Pulpit It is a substantial foundation for skyscrapers to turbine engines Associatoin 500 anyone building or operating a radio . is built from drawings made -278 receiver. Chicago Technical Col - WOS Jefferson City, Mo.. by draftsmen. The American Missouri Book contains 300 lege, founded in 1904. is State Marketing Bureau 500 -440.9 pages, size 5'.; "America's Oldest and Bridge Co. alone, employs 600 WPAC by 83/z inches, and is bound with Largest School of Spe- to 750 draftsmen. The drafts- Oknndgee, Okla., Donaldson standard, stiff cover. cialized Engineering.' It man works hand in hand with Radio Co. 100 -360 offers to resident stu- the engineer, the WPAJ New Haven, Conn., Doolittle dents 2 architect, the Price $1.00 -year and 3 -year builder. The better - trained Radio Corp. 100 -269 courses in Architecture WPAK and Engineering, lead - men rise quickly from positions Agricultural College, N. Dak ing to diplomas and B.S. paying $35 to $50 per week to North Dakota Agricultural THE E. I. COMPANY degrees. Short courses, $300,$400 and $500 per month College 50 -275 Sole Distributors also, in Drafting, Plan Reading, Estimating, and more. WPAU Moorehead, Minn., Concordia THE CONSRAD COMPANY Building Construction, We have been teaching Draft- College 10-286 233 Fulton St. New York City etc. Over 1000 men en- ing for 21 years. Thousands of WPAZ Charleston. W. Va., John R rolled each year in day our graduates are in high sala- Koch (Dr.) 10-268 and evening classes. 50% ried positions, today. We train WPG Atlantic City. N. J.. Munici- of them accept part -time you in 10 months or less. No positions before gradua- pality of Atlantic City . . 500 -299.8 tion. 90% of them get special preparation or talent WT'SC State College. Penna., Penn- positions immediately required. sylvania State 500 upon graduation. Tuition low; payments easy. College -405 Professional out t included,or WQAA I'arkesburg. Pa., Horace A. Opportunities credit will be allowed if you Beale, Jr. 500 -220 in Chicago to Earn have instruments. WQAC Amarillo, Tex., Gish Radio while you Learn Service 100 -234 WQAE Springfield, Vt., Moore For those who can come Mail Now Radio to Chicago, there is a Coupon News Station 50 -275 onsrad splendid opportunity to Today, find out what Draft- WQAM Miami, Fla., Electrical Equip- learn Drafting, Engi- ing may mean to you as your ment Co. 100 -268 neering or Architecture life work. We have made the WOAN Scranton. Pa., Scranton Times 100 at the College while earn- test easy, with no obliga- -250 ing expenses in part -time for, WQAO New York. N. Y., Calvary positions. If interested, tion, we send you a Vocational Baptist Church 100 -360 write for 52 -page Blue Test Lesson free. Clip coupon WQAQ Abilene. Tex., West Texas Book of Resident Courses. at the top of this ad. Mail now. Radio Co. (Abilene Daily S TOPSGLARE Reporter) 100 -360 I College WQAS Lowell, Mass., Prince -Walter PREVENTS AUTO ACCIDENTS ChicagoTECH N CAL Co. 100 -252 "Glarof" protects auto -drivers from the blinding Dept. 445, 118 East 26th Street, Chicago WQJ Chicago, Ill.. Calumet Rainbow (headlights of the other fellow's car or a low, direct ,un- It is a simple inexpensive device applied to Broadcasting Co. 500 -447.5 inside of windshield Instantly: held fast without WRA.A Houston, Tex., Rice Institute. 100 -256 bolts or screws by amazing new method; will not WRAF Laporte. Ind.. The Radio Club 15 -224 e ork off on rough roads. Try one on your car a week WRAL St. ('roix Falls. Wis.. North- at .air risk; if it does ant make driving easier, safer, t, is I costs you nothing. Magnified 225 ern States Power Co. .. 100 -248 Diameters WRAM Galesburg, Ill., Lombard Col- HOT SELLER FOR AGENTS Auto owner agents wanted to use and introduce This is what the tip of a fly's leg lege 100 -244 Clarof4. WRAN Waterloo. Iown. Enormous, uncrowded field. Sella like wild - is like when seen thin the Black Hawk e -every car owner buys. $12 A DAY up to $7,500 Electrical Co. 10 -236 a year to county agents. Territory going fast. Write ULTRALENS WRAO St. Louis. Mn., St. Louis ter SPECIAL FREE GLAROFF OFFER and further Radin Service Co. 10 -227 Ictaifs. This is a big opportunity, so don't delay, MICROSCOPE WRAV Yellow Springs, Ohio, Antioch (mite today. College 100 -263 GLAROFF MFG. CO. Any amateur can WRAW Rending. Pa., Avenue Radio 166 Plumbers Bldg. Situa Falls, S. Dak. immediately start & Electric Shon 10 using his Ultra - -234 lens to examine WRAX Gloucester City, N. J., Flex - the edge er a on's Garage 100 -'(.4 razor. the mesh WRBC Valnarniso, Ind., Immanuel "LIGHTING FIXTURES" of a cotton shirt, T.ntheran Church 50n -278 READY TO HANG t h e bacteria I n dirty water. No WRC Washington. D. C., Radio Corp Direct from manufacturer. technical training of America 500 -468.5 Completely wired including glosseau- $7.50 for Complete Outfit Prepaid. required, yet hun- WREO Lasing. Mich., Reo Motor Send for Catalogue No. 26 dreds of settn- Car Co. (.lust off the Press) tists and teachers are using this instrument. Gives enor- 500 -285.5 mous magnification and perfect definition. Send $7.50 for WRHF Washington, D. C... Washing - Special Proposition to Dealers complete outfit. Send for descriptive literature. ineton Radio Hospital Fund 50-256 WRK Hamilton. Ohio, Doron Bros. ERIE FIXTURE SUPPLY CO. Scientific Apparatus Corp , Dept. 203, Milton, Pa. Electrical Co. 200 -270 Desk B Erie. Pa

www.americanradiohistory.com 126; Science and Invention for April, 1925 Power Call & Wave Letters Location and Name Lengt WRL Schenectady, N. Y., Union Col- lege 500 -360 WRM Urbana, Ill., University of Illi- nois 500 -273 WRR Dallas, Tex., City of Dallas, Police and Fire Signal De- partment 200 -261 WRW Tarrytown, N. V., Tarrytown Radio Research Labora- Easy to tory 500 -273 WSAC Clemson College, S. C., Clem- Want to make big, easy money? Learn son Agricultural College.. 500 -336.9 Learn at Home to install, operate, repair, construct how VISAD Providence, R. I., J. A. Fos- week for and sell Radios. Write now for facts ter Co. 100 -261 Big money every the amazing opportunities for fascinating easy work -won- about of WSAI Cincinnati, Ohio, United States Radio experts, and our special offer a Playing Card Co. 500 -325.9 derful future. Hundreds of big 1000 -mile receiving set, and how paying positions in this huge FREE by mail. WSAJ Grove City, l'a., Grove City you can quickly train at home College 250 -258 new industry! Be a Radio Expert WSAN Allentown, Pa., Allentown Call No previous experüence necessary. Anyone Publishing Co. 10-229 with ordinary education can now learn Radio WSAP New York, N. Y., City Tem- home -study plan. 250 uicklyunderoursrmplified to represent our ple, Adventist Church -263 We need men right now River, Mass., Doughty & Association. Be the Radio expert In your WSAR Fall neighborhood. your Welch Electrical Co. 100 -254 t. Huneds about wantRadios and WSAU Chesham, N. H., Camp Marien- advice how to operate. You can earn enough feld 10-229 money right from the start to pay for course. Nothing difficult about it. WSAV Houston, Tex., Clifford W. Low cost and easy terms. Vick Radio Construction Co. 100 -360 More MoneyforYOU inRadio WSAX Chicago, Ill., Chicago Radio Lab. 20 -268 HOUSANDS of Radio Experts are WSAZ Pomeroy, Ohio, Chase Electric needed to design, repair, maintain, Shop 50-244 to operate Journal 500 -428.3 sell radio apparatus, WSB Atlanta, Ga., Atlanta as ship and 1,000 -MILE WSL Utica, N. Y., J. & M. Electric broadcasting stations, Set Co. 100 -273 land operators, to go into business; to in- Receivingto supply WSOE Milwaukee, Wis., School of demonstrate, superintend and Don't misS this big special offer Engineering of Milwaukee 100 -246 struct, sell, FREE all parts necessary to construct a for scores of other big paying radio jobs. high -grade 1000 -mile receiving set. You can WSY Auburn, Ala., Alabama Poly- sell this set alone for practically the entire technic Institute 500-250 And now, you can easily become a Radio cost of the course. Send for the facts now. WTAB Fall River, Mass., Fall River in time, out all about this big -pay field. Address Expert. Studying at home spare Find Daily Herald Publishing Co. 100 -266 a Radio Radio Association of America WTAC Johnstown, Pa., Penn. Traffic you can quickly qualify for splendid 4513 Ravenswood Ave., Dept. 64 Chicago, III. Co. 150 -209.7 position. Astonishingly small cost. Famous WTAF New Orleans, La., Louis J. radio instructors give you individual help Gallo 10 -268 Guaranteed. WTAL Toledo, Ohio, Toledo Radio & by mail. Training Electric Co. 10 -252 WTAM Cleveland. Ohio, Willard Stor- Free Employment Service age Battery Co. 1500 -389.4 re- WTAP Cambridge, Ill., Cambridge Ra- Hardly a week goes by without our dio & Electric Co. 50-242 ceiving urgent calls for our graduates. "We WTAQ Osseo, Wis., S. H, Van Gor- need a competent Radio Engineer " -"We den & Son 100 -254 in addition WTAR Norfolk, Va., Reliance Elec- want men with executive ability tric Co. 100 -261 to radio knowledge to become our local WTAS Elgin. Ill, (near), Charles E. managers " -"We require the services of RADIO Erbstein 500 -302.8 demonstrators" -these are WTAT Boston, Mass. (portable), Edi- several resident Storage "B" Battery son Elec. Illuminating Co. 100 -244 just a few small indications of the great va- lice"a Lasts Indefinitely -Pays for Itself WTAU Tecumseh, Nebr., Ruegg Bat- riety of opportunities open to our graduates. of before. Recharged 10 Economyy and performance unheard by tery & Electric Co. -242 at a negligible cost. Approved and listed as Standard WTAW College Station, Tex., Agricul- Rodio Authorities meiuding Pop. Radio Laboratd FREE -Receiving Set leading Radio News Lab., Lefax Inc. ad ies. Prñ- tural & Mechanical College Sci. last. Standards, with Solid Rubber Case, s, insur- port ,at inst ,i, ne. Equipped heavy glass jars, Heavy of Texas 250 -270 e against .c d and leakage. Extra and Special Parts rugged plates. Order yours today! WTAX Streator, Ill., Williams Hard- state number pf batteries 50 of instruction in- MONEY anted an y we II nip aey ware Co. -231 Our course practical SEND NO Oak Park, Ill., Oak Leaves order'.Peirpreasman afteertexamining batteries. i6 per cent discount for WTAY cludes not only several of our own special order now! Broadcasting Station 500 -250 cash with order. Mail your patented instruments, but in addition we BATTERY COMPANY WTAZ Lambertville, N. J., Thomas J WORLD Ill. 15 -261 furnish material and diagrams for building 1219 So. Wabash Ave., Dept. 83, Chicago, McGuire o "A- WTG Manhattan, Kans.. Kansas State without additional cost. Makers ÁmPSlab0. 120 Amp. 814.y14Ó Amp $18.00. receiving sets-all Prices: s -sou equipped path Solid Rubber Roo . Agricultural College 50 -273 is an absolutely complete course which WTIC Hartford, Conn., Travelers In- This surance Co. 500 -348.6 qualifies you for the government first -class FOR WWAD Philadelphia, Pa., Wright & license and for the big -pay jobs in Radio. World RADIO Wright, Inc. 100 -250 STORAGE BATTERIES WWAE Joliet, Ill., Lawrence J. Crow- We HelpYou to Big -Pays WEAffW6N,WJS, .11S60 si5FAEsW.) ley (Alamo Ball Room) 500 -242 [PM WWAO Houghton, Mich., Michigan Positions College of Mines 250 -244 Scores of young men who have taken our course WWI Dearborn, Mich., Ford Motor are already earning from $75 to over 5200 a week. Co. 250 -266 Merle Wetzel of Chicago Heights. Ill., advanced to Radio Engineer. increasing his Greatest Bargain WWJ Detroit, Mich., Detroit News. 500 -352.7 from lineman WWL New Orleans, La., Loyola Uni- salary 100% even while taking our course! Emmett Ever Offered - versity 5 -280 Welsh, right after finishing his training, started earning $300 a month and expenses. Another 6 -Shot Finest graduate is now an operator of a broadcasting Perfected Revolver ELECTRIC HOE station PWX of Havana, Cuba, and earns $250 a Sells elsewhere at $12.00. Quick as a month. Still another graduate only 16 years old is flash, safe, great penetrating power and averaging $70 a week in a radio store, and we help true marksmanship, Blue steel or nick- our graduates to positions like these. eled, 38, 32 or 22 caliber all same price. or money back. SEND NO MONEY. Satisfaction If you FREE BOOK Pay postman on arrival $6.45 plus postage. Send for PAY ALL POSTAGE There's more money for You in Radio. Find out send money with order WE lias meant to hundreds of our grad- Federal Mail Order Corporation what this field Dept. E, New York uates -and how you too can profit in it. `Rich 414 Broadway, Rewards in Radio" has just been printed. It is filled with the latest Radio facts, figures and illus- j- now trations of tremendous into rest to you. Right CATA -if you are at all ambitious -send for this valu- illAD110 able free book. Write Now while our Special LOG offer is still open. Fill out the coupon -and mail it now! Institute, Dept. 14FB, Wash - AND UPS FREE National Radio HOOK the very new- D. C. fresh from the press, contains g ineton, Our great new catalog. sssones-hundreds of Dept. 14FB est in complete nets, parts and acr wonderful mead PTATIONAL RADIO INSTITUTE, testify king most D. C. mpOQe instructions diagrams Washington, reliability.C FREE. SEND QUICK foroyour copy. (Please Without obligation send me your book "Rich Rewards v ctical popular acta m Radio.) in iactada same of friend interested in Radio." which tells all about the opportunities CO. Rodio. how spare time study . at home will qualify me THE BARAWIK Chicago can 120 32.40 So. Clinton Street quickly Certified Dent. these pitions. and 1 how your Employment Service helps me to secure a big -pay lob. INVENTORS Age PATENTS Name POWER -AUTOMOTIVE Street M. P. L.AUGHLIN York Hoeing with flashlight strapped to hoe handle. City State 47 West 42nd Street New

www.americanradiohistory.com 1268 Science and Invention for llpril, 1925

Opportunity Ad -lets YOU will find many remarkable opportunities and real bargains in every month by reliable these columns. It will pay you to read and investigate the offerings made firms, dealers and amateurs from all over the country. No matter what you may be seeking, automobile accessories, the opportunity to make money, or anything whether supplies, month. else, you will find listed here the best and most attractive specials of the Advertisements in this section twelve cents a word for each insertion. Name and accompany all classified address must be included at the above rate. Cash should advertisements unless placed by an accredited advertising agency. No advertisement for less Ten per cent. discount for 6 issues, 20 than 10 words accepted. pe_ cent. discount for 12 issues. Objectionable or misleading advertisements not accepted. tisements for the June issue must reach us not later than April 10th. Adver- The Circulation of Science and Invention is over 175,000 and climbing every EXPERIMENTER month PUBLISHING CO., INC., 53 Park Place, New York City, N. Y.

Agents Wanted Agents Wanted (Continued) Business Opportunities (Continued) Agents seller; Jew Rubber -Best Repair for tires and A Rare Opportunity: Start Mail Order Business: Watch Get tubes; supersedes vulcanization at a saving of over 800 per Money in your mail. "Latnbert's Mall Order Se- yourself grow. Costs 5c. Sells by 31ail for $1. Informa- crets" contains successful methods never cent; put it on cold. It vulcanizes itself in two minutes and Lon free. Write before published. is guaranteed to last the life of the Quick! Desk 11. Surety Service Com- larticulars free. Leon Lambert_ 670 -D Kaufman Bldg., tire or tube; sells to pany, 551 Harvard St., Rochester, Y. every auto owner and accessory dealer. For particulars how N. Wichita, Kansas. to make big money and free sample, address Amazon Rubber Co.. Dept. 601, Philadelphia, Pa. Robt. H. Ingersoll of $1 Watch fame wants good men to Earn $25 weekly, spare turne, writing for newspapers, seli his Dollar Stropping outfit, an ingenious invention for magazines. Experience unnecessary. Copyright book free. sharpening all makes of safety Agents-Write for Free Semples. Sell Madison "Better - razor blades. Great eco- Press Syndicate, 987, St. Louis, Mo. Made" notnie value. Meeting with nationwide approval. Easy to Shirts for large 3fanufocttrer direct to wearer. No sell. Big capital or experience required. Many earn $100 weekly and repeat business. Agents having remarkable suc- Free Booklet, How to become Successful in Real Estate. bonus. Madison Mills, 564 Broadway, cess. Full particulars. Itobt. H. Ingersoll. 47611 Broad- Macdonald Cooperative Realty, San Diego, California. New York. way, New York City. Big money and fast sales. Every owner buys gold initials for his auto. You charge $1.50; ¡make $1.35. Ten Marvelous New Invention -400 Per Cent Profit Johnson's orders daily easy. Write for particulars and free samples. Liquid Quick Mend. Tremendous demand. flan unique. Chemistry American Monokram Co. Dept. 71, East Orange, N. J. Act quick. Over hundred other fast- selling specialties. J. E. Johnson & Co., Dept. 76, 321 W. Chicago Ave.. Learn Chemistry at Home. Dr. T. O'Conor Sloane noted Chicago, Ill. educator Only one sale a day means $200 per month. Five sales, and scientific authority, will teach you. Our home $1,000 per month. Marvelous new adding machine. Iie- study correspondence course fits you to take a position as tails 015. Work equals $330 machine. Adds, subtracts. Free Book. Start your own little mail order business. chemist. See our ad on page 1174 of this issue. Chemical multiplies, divides automatically. Speedy, accurate, dur- Pier, 911 Cortland St., N. Y. Institute of New York, 66 W. Broadway, New York City. able, handsome. Five -year guarantee. Offices, stores. fac- MEvnu11mamnuumnuau11n,n11nmuuu,m,,,,,n,n1111,,,,11,,,,,, , 1 11, 1. 1 tories. garages soy one to dozen. A fortune for live agents. Agents -World Radio anal Sporting Manual. Quick 1,,, 1,n, 1,1 11n,u,u,,,,,,,,,1111 1 11,1111,. Write quick for protected territory and free trial offer. Cleanup. Sample 10e. Reallne Co., ROO, W. Washington, Lightning Calculator Co., Dept. W., Grand Rapids, Mich. Chicago. Correspondence Courses Earn big Used correspondence courses of all schools sold, rented money fast applying gold initials to autos. Make Money Applying Monograms on A utomabiles. Easiest Every owner buys -$1.35 profit on $1.50 sale- thing today. and each au;, ed. List Bee. (Courses bought.) Lee particulars You simply transfer Gold Laid initials from Mountain, East Chattanooga, Tenn. end samples free. WrLe quick. Lithogram Co., Dept. 19, Paper. Takes f minutes to make $1.50 sample FREE. East Orange, N. J. Rake, 325 Harrison, Boston, Mass. Correspondence Courses bought and sold. Hanfllns, 799 -a Earn $10 daily silvering mirrors, plating and refinishing Succeed Broadway, Ness York. metalware, With Your Own Products -Formulas by Experts. chandeliers, bedsteads, headlights. Outfits fur - $fanufaeturing Processes. - n!shed. N. Decle Trade Secrets. Modern Master 110191¢.11Imnuamn,mn annnnmm, nm n,,,,,,,,,,,,, o,,,, l,,,,,,,,, l m, l ,,,,,,,,,,,,,,,, ,,,.,,,,,,, . Laboratories, 1133 Broadway, New York. Methods. Sal Israel ion guaranteed. Catalog free. I). '17mxly Company Washington, D. C. Educational $60 -$200 a week. Genuine Gold Letters for store windows. Easily a,,nlied. Free samples. Liberal offer to Rummage Sales Make Daily. general agents. Metallic Letter Co., 441 B., North Clark, $50 Otter wonderful values. Correspondence We start you. Wholesale Distributors, Dept. 171, 000 Courses -All schools sold complete et Chicago. Division St., (h!cauo. lowest prices. Easy terms, money -back guarantee. Courses bought for rash. Catalog Free. Mention Subject. Economy Write and learn how to start profitable business without Big Money and fast Educator Service, 442 -H Sansone, San Francisco. capital or experience. Silvering mirrors, refinishing auto sales; every orner b:uvs gold initials for his auto. You charge $1.50, ¡sake $1.91 profit. 10 headlights. tableware plating. Outfit furnished. Interna- orders dally easy. tional Laboratories. Dept. 25. 309 Fifth Ave.. New York. Samples and information free. World lfonogr:un Co., Dept. 32, Newark. N. J. Electrical Agents -Be independent, make big profit nvith our soap, Agents-Signs far stores toilet articles end hoaschntd necessities. Get free sample and °Slices. Entirely new. 250 Meters $2.98. Practical, twentieth horsepower 115 volt week easily ruade. World Signs, T160 W. Washington, case offer. Ho- Ro -Co., 2719 Doduer, St. Louis, Mo. Chicago. alternating direct current. Order Now. Pay Postman. Perry Trading Co., Dept. 13. 815 Lake, Racine, Wise. Make $17 Day. -Finest extracts, fond products. toilet 11,,,p11111111r,,iiiilll1111,11111111,,,nnnn11,,,1,,,1111m11m1,11111m1111111111muuu,,wmu11,1.111111111111111 Preparations, household necessities. Credit; sample ease free. Write for amazing offer. Perkins Products. 1t -30, Hastings, Nebr. American Made Toys For Advertisers

Wonderful Invention eliminate: needles far phonographs. 0ppertenity to start Manufacturing Metal Toys and Nov- 24 words -355 Rural Weeklies $14.20. Ad- Meyer. 4112 Preserves records. Abolishes scratching. Day's supply in elties. Nn experience necessary. Enormous demand exceeds SI, Hartford. St. Louis, Mo. Pocket. $20 daily. Sample nn annroval if rectuested. supply. We furnish, at cost, casting forms for production Everplay, Desk 114, McClurg Bldg., Chicago. and hay entire output, also place yearly centrant orders. 11111111m1111111,.111111m11m 1om.,m111m11mmm1111m11111111111111111111,m11m1.11111:,,,,n,,,,,,11111,1.,1111.11 Casting forms made to order. Catalog, advice and Infor- $10 daily silvering mirrors. plating and refinishing lamas. mation free. Metal Cast Products Co., 1696 Boston Road, For inventors reflectors, autos, beds, chandeliers by new method. Outfits New York. furnished. Write Gunmetal Co., Ave. D, Decatur. Ill. We Develop Your Ideas into commercial shape for pre- m,n,nm,,,,,nunnu,,,,,,,,,,,,,,,,,,,,,,11m,,,,,,, sentation to purchasers making working models, drawings, Earn money at home. Addressing, mailing circulars. experiments or tests. Courtesy, efficiency, secrecy and ample Experience unnecessary. No selling. We pay weekly. York Battle Photos and War equipment; 30 years' experience. Ducorron -Rich Engineer- Supply Co., Dept. 120, 309 FitUs Ave,. New York. Relics ing Co., 504 Pacific Mutual Bldg., Los Angeles, Cal.

Agents: 500 per cent Profit, "Happy Mane Maker Sham - For Dens: Relics Collected front Europe's Battlefields. Unpatented Ideas Can Be Sold, I tell you how and help ono" builds your own big business. Martin of Indiana made Firearms. medals. helmets. etc. Illustrated catalogue and You make the sale. Free particulars (Copyrighted). Write 575.00 in one day. Missouri man made $750.00 one month. sample War photographs 25c. Lieut. Welch, 2117 Regent W. T. Greene, 003 Jenifer Bldg., Washington, D. C. Excluslte territory. Gee. A. Schmidt & Co., 216 West Place, Brooklyn. N. Y. Not Ave., Chicago. Your Chemical problems solved and working process fur- 111111 111111111111 , 1 1 1 ...... 1 1111,,,11,,,,,,111 .:: .. 1 1 1 1 1111 1 1 1 1 1 1 11 1, , . 1 1, m, m, a 1111 1 1, 1, 1 1 1 1 1 1 1111 am, 1,,. .,,,,,,,,,,,,,, .,11, , nished for Five Drl'ars. Write me. W. Stedman Rich- Build splendid business making chipped glass number ards, Consulting Chemist, Box 2402. Boston. Mass. and name plates. Particulars free. Simplex Co.. Dept. Books 93. 1133 Broadway, New York. Patents are expensive. Your ideas can be sold without Ideophonie Primers, $1.94: Chinese, French, Spanish. this expense. Complete instructions. $2. Box 61, Pon- Agents -Quick sales, big profits, outfit free. Cash or Languages, 8 West 40th, New York. tiac, Michigan. credit. Sales in every home for we high class line of Pure Fond Products. Soaps, Perfumes. Toilet Articles. etc. Free -Upon request will send you my literature fib,s- Patents -Send for booklet. Contains va lusble Informa- Write today for money -tusking plans. American Products trating the following hooks. Astrology, Character. Clair - tion for inventors. Bank and commercial reference,. Co., 2362 American Bide., Cincinnati. Ohio. voyance. Concentration, Healing, Hypnotism, Magnetism. Prompt service. twenty years experience. Talbert & Tal- Medtumship, Personal Magnetism, Personality. Physiog- bert. Tt,castered Patent Lawyers, 557 McGill Building. $4 cash with every sale of Cant. Burke's Fire -Foe. only nomy, Salesmanship, Seership, Success, Sex. Will, Yogi We shin, ten. D. C. pistol -type extinguisher on market: operates with one hand; Philosophy. Gazing Crystals, etc. A. W. Martens, E. E. used on U. S. airplanes; undersells all competition; stops 6. Burlington, Iowa. Inventors -Read new interesting Booklet- Perpeloal Mo- bandits as quick as it nuts out fires; factories and institution (illustrated) 10 cents. Lightning Method Publishers. tions buy in quantity; $20 a day easy: write for sales plans. Master Key Greatest Success hook. 410 pages, $2. a. Pox 999. Long Beach. Calif. Burke Fire -Foe Sales Co., Desk G. Cincinnati. Illustrated catalogue 10c. Phipps Science Library, 1011 Belmont, Chicago. Full or Time to Sell on liberal New Frrd diseributar using one coil. New invention, Agents Wanted Part imnrnve on it And oak" $100.000. Send $2.00 for blue- commission new Thermostatic Automatic Carburetor control ts9nt, A. Attachment for Ford cars. Increases mileage 100 %. No D. Johnson. 7601 Washington Ave., Erle. Pa. holes to drill. Attached in 2 minutes. Does automatically Business Opportunities exactly what Ford Manual instructs driver do by hand. Cashing In-If you have a sound commercial invention Cadillac now using Thermostatic Carburetor Chntrol under to sell write American Patents Corporation, Barrister Dollars yearly in your backyard. No mnshrnom dope. Building, Washington, D. C. Rlaneke license. Write at once. A. C. Blanche & Co., Particulars free. Metz, 313 East 89th, New York. Dept. 52 -E, 602 W. Lake St., Chicago. ,,,,,, You eon have a business -profession of your own and earn f srn E.4 big money selling twenty million anxiously big income in servire fees. A new system of foot correction: Formulas waiting to buy. Holes in stockings repaired without darn- readily learned by anyone et home In a few week's. Ea se ing. Special selling system furnished agents assures gen- terms for training, openings everywhere with all the trade 250 valuable formulas 10e. 700 formulas 35e. Rodgers e -ors income. Large profits. protected territory. sure yon can nttc,wd to No ennital renydred or goods in hay, no Company, 813 Locust, Cincinnati. repeater. Sample 35e. Darn E -Z Laboratories, Dept. 153 agency or soliciting. Address Stephenson Laboratory. 18

11 11 11 11 1 418 N. again Street, Dayton. Ohio. t'n ^Ic Rey, Boston, Mass. , n 1111 m m m m 11111 1 o n o, 011,,,,,,,,,,11 1 1 1, 1 1 111111 1 1 1 1111 1 111111 m,1111 m 11 m 11 n, m u m 11m n ni m 111111 m

$100 Weekly-Pleasant Work: Appointing Meal acento to ,top Ple'ding! Be Successful. Operate a Tire Ilenair For Sale intredure Mother Hubbard Foods; no canvassing; no dcliv- Shun. Sinke hug profits in any locality. We tenets you and e-Ing: no money invested. Adam Inthout, 550 Congress. furnish complete equimnents $100 tip. Book of Onporiunity Fer Sale. Telegranhone Electro- Magnetic Radio Re- Chicago. free. Haywood's, 1512 South Oakley Avenue, Chicago. corder. Box 93, Creighton, Pn.

www.americanradiohistory.com 1269 Science and Invention for April, 1925 Patent Attorneys (Continued) For Sale (Continued) Machinery and Tools Millions spent annually for ideas! Hundreds now wanted! and uMol Citalo une For Sale. My Invention for Leveling attachment for Concrete Building Block Machines Patent yours and profit! Write today for free book -tells lameras. Patent pending. Max Sturm, Jr., Union Beach, t ree. Concrete Machine Co., s. hole to protect yourself, how to invent, ideas wanted, how Mo. Industries, Inc., 212 P. O. Box 28, Keyport, N. J. 1 ouis, we help you sell, etc. American Kresge Ilhlg., Washington, D. C. m sue l 7,1111,,111111,111111,,,11,11.1111111,,,,,1111,1111111111111 Manufacturing The Patentome. Impartial advice to Inventors and Man- ufacturers. Mailed on request. Anderson & Son. Patent For the Photographer 1865. 637 F SI_. order: Metal articles, simple, or complicated machin - and Trade Mark Lawyers, Established To l'arma En- Washington, D. C. a Camera? Write for free sample of our big ry. Models, tools. patterns. Experimenting. Have you and earn Station, Cleveland, Ohio. magazine, showing how to make better pictures ineering Works, Brooklyn Conception" to ho Photography, 118 Camera House, Boston, Inventors -Send for form "Evidence of money. American n signed and witnessed, Form, feo schedule. information free. 17, Mass. Lancaster and Aihvine, Registered Patent Attorneys in Miscellaneous United States and Canada, 242 Ouray Bldg., Washington. 11,,,,,,,,1,,,,11111111'11 D. C. Beautiful registered hull pups cheap. Bulldogs, 501 Games and Entertainment ockwood, Dallas, Texas. Monroe Miller. Ouray Bldg., Washington. D. C. Patent Electrical Expert Free ]Slue Boole Plays. Stage Attorney'; Mechanical, Tricks, Puzzles. Jokes, Magical Apparatus, Get Posted -Good prices paid for butterflies, insects. gives candid advice. Acts and Sensational Escapes. page 1270. Supples. Mind -Reading cata- ee Sinclair display advertisement Send 10c for 160 -page illustrated 1922 professional for my free Guide Books "flow to Dept. 549, Oshkosh, Wis. Patents. Write logue. Oaks Magical Co., Artificial Marble, sanitary flooring instructions. ornamental Obtain a Patent" and "Invention and Industry" and "Rec- asting, concrete, plaster, papier -mache, decoration garden ord of Invention" blank before disclosing inventions. Send 11111111,1111,,,,, h urniture, 15 years instructing the public, particulars and model or sketch of your Invention for Instructions. Prompt- C. Mahler, Huntington, N. Y. for above information. Clarence !00 illustrations free. ness assured. No charge ]lank Health A. O'Brien Registered Patent Lawyer, 9291 Security Office, %Vash- Used Printing Presses. Tyne supplies catalog free. Building. directly :terms street frein Patent Free -Stop using tobacco. We will give free informa- orfollc Press Works, Drawer 1, Ballentine, Norfolk, Va. ington, D. C. See page 1245. tion how to conquer habit easily and permanently. Results Tobacco League Box M, Omaha, Neb. auto electrician, Wire - Trade Marks Registered-A compre- guaranteed. Anti- Learn Electricity at Home-Ise an Patents Procured: and or Pay. Address (leo. Willoughby. hensive, experienced, prompt service for the protection 1 man, Repairman-Big fur - 1111,1,,,,,,1, 1111,,, 1111, 111,1 1,1,,,, 1111 ,1,111111111,111111111111111111 of ideas. Preliminary advice gladly 11nm11, 1111, 1111, 011,, ,11,,,,m11111111,,,,,,,,11,,,,,1 Electrical Engineer, Saginaw. Mich. development your without charge. Booklet of information and form nished 120 Help Wanted other formulas. Irree valu- for disclosing idea free on request. Richard il. Owen, Your favorite beverages and Bldg., Washington, D. C., or 41 -T Park Row, New able inforumtion. The Formula Co. , Dept. 1f, 122 West Olsen Needed Everywhere. Work home or travel. Bove St., Seattle, Wash. York. Detectives Write, George Wagner, former Experience unnecessary. Application blanks. complete Detective, 1968 Broadway, N. Y. in life. For the man with the small Get your own patents. Government Get a big start instructions $1. Cutting Bros., Csunpbell, Calif. income I will instruct Foe in the following : how to slop Mirrors, French plate. Easily learned, im- paying rent. how to build your home without borrowing Write Silvering Works, Excelsior in the building Cooperation in obtaining. marketing patents. mense profits. Plans free. Wear Mirror any money; have had 37 years' experience Inventors. 635 F Street. trades. For particulars write: James J. J. Eastman. Dealer Chartered Association of American springs, Mo. D. No. Washington, D. C. in Real Este t. e. General Contractor & Builder R. Travel. Excellent oppor- 5. Youngstown, Ohio. Detectives Earn Big Money. sketch or model for advice and exact cost Great demand everywhere. Experience unnecessary. Inventors -Send a tunity. System. 1974 of Ask for our free book, "Flow to Obtain Particulars free. Write. American Detective patent. should know. Estab- Y. Patent." Tells what every inventor Broadway, N. Motorcycles- Bicycles lished twenty -eight years. Ilighest references. Prompt Chandiee & Clandlee 476 an hour cutting blanks at home; anywhere; service. Reasonable charges. Earn $1.20 ens-elope. Don't buy a Bicycle Motor Attachment until you get Seventh, Washingain11nN11mm11111111,11 poodyeatime. Men Send addressed reply Shaw Mfg. Co.. Dept. 6. ok. our catalogue and prices. G Sy., 147 W.y Ne Galesburg, Kansas. nn,,,11,m,1111nu1m,m11m1111m"munit. Men to Build Radio in Leon Lambert, Patents 670 -H Kaufman Bldg., Sets n. KassaKansas. Musical Instruments Patented or unputented. Uncrowded profession of Inventions commercialized. Become a Landscape Architect. «'rite Adam Fisher 11Úg. Co., 205 Enright, St. Louis, Mo. opportunity for money -making. Easily mastered easy credit terms. wonderful book. Ameri- Violins -Deep, Mellow, Soulful -on by mail. Earn while you learn. Write for wonderful instruments of my own make. Devel- to obtain Japanese pat- 66-E, ,Newark. New York. High grade. Japanese Patents. If you wish can Landscape School, opment of many years' expertness. Write for book. Gustav cots entrust to one through my associates in your country. A. Henning. 2124 Gaylord St., Denver, Colo. Mori, Registered Patent Attorney, 307 Haraiukn, Exceptional opportunity; corn big money. Takeaki Be a Detective- Particulars free. Sendagaya, Tokyo, Japan. Travel. Big rewards. Established 1909. (Patent Pend ins.) R',auler dollar instrument smybody Westover Bldg., Kansas City, 1111111,1111111111111111111111111111111111111111:11 Write C. T. Ludwig. 1417D play. everybody muon., d. Imitate orchestra. become pro- mm,mnrmmlmm11,m11nu1n11111,,,,nunmm11u1n11u11n,111u1 Mo. fessional entertainer; oilier valuable information. Multi - tone, 448K W. 3 h. New York. Personal weekly, spare time, writing for newspapers. Earn $25 Copyright book free. magazines. Experience unnecessary. ,1111111111,,,.1.,,11111 Lonely Hearts -Exchange letters; stake interesting new Press Syndicate, 986, St. Loads, Mo. Novelties friends through nor romantic club. Write Eva Moore, ]lox flies. insects. 908, Jacksonville, Florida. page 1270 Catalog See Sinclairdl play advertisementt Magic goods, cards, books, novelties, tricks. Get acquainted. Make new friends. Exchange Letters. free. Clifford Fenner, 2401 Jefferson, Louisville, Ky. Enclose stamped envelope for plan. The Lilly Club, Station Wanted -Mail Clerks to handle mail on trains (travel), ,.11,1111,,,11111111111.11 li, Cleveland, Ohio. Special Agents. 111111 11111, ,111111111111: Forest Rangers, Guard Forest Reserves, 11111i111,111111,iii, Write Ozment, The stake investigations. Big Pay. Lonely -Join our Club. Make friends everywhere. Par- Coacher, 293, St. Louis, Mo., quickly. Old Money Wanted ticulars free. Write Mrs. Mathews, Box 26. Oakland. Calif. Make Money at home writing showcords. We instruct $2 to $500 Each paid for hundreds of Old or Odd tieing. new friends. Write Dolly Grey Club, 61J Rond. Toronto, Send 10e for Lonesome! Make and provide work. Kwik Shotecard, Keep all old money. it may be very valuable. Box 188K Denver, Colorado. Stamp appreciated. Canada. new illustrated Coin Value Book. 4x6. Guaranteed Prices. Get Posted, We pay Cash. Clarke Coin Company, 14 Men Wanted for Detective Work. Experience mmeres- Street LeRoy.,1 sory. Write J. Ganar, former Govt. Detective, 104, St. 11Y11 ,1,11,11,1,111111111,111,,m,11 11111111111111,1,1,1,111,11111111111, /,1 11,1 1111111, Phonographic Supplies Louis Me. lllll 1111 N. car, train Old Coins Build Your Phonograph. Spring Motors, Electric Motors, Firemen. Brakemen. Bagganenten. Sleeping Accessories. Latest Equipment also $110 -$200. Experience unnecessary. 897 'ronearnts, Amplifiers, porters (colored), list. all in Radio Mechanism and Cabinets. Catalog mailed for ten Railway Bureau, East St. Louis, Ill. White Cent 2c Bronze, 3e Nickel. bargain price Baldwin Block. Indian- M. Arcy, Box 483, Muskogee, Oklahoma. cents. Hoosier Mfg. & Supply Co., for 25e. apolis, Ind. Want a Government Job? $95 to $250 month. Men- ,,,,,111111,11111,11111.,11n111n,,,,1,,,,1,1n11,,,11n,,,m1,,,1,m1u11,,,,mu , msum 11111111111111111111111111 mu11m11,nnum1111111 women. 18 up. Steady work. Pleasant duties. Short ®w,ammm1mmnmm,mmnmmmn1111nuu,111 hours. Vaeatinna. Common education usually sufficient with our training. Experience unnecessary. Full partleIN Patent Attorneys Photoplays, Stories, Etc. lars free. Write immediately'. Today sure. Franklin Rochester, N. Y. Patents -Our ]look "Row to Obtain a Patent sent free farm; Institute, Dept. B23, 5 $ For Ideas. Photoplay Plots Accepted any upon request. Contains full information about patenta, $ Advice free. send us a sketch of rev ised, criticised, copyrighted, marketed. 1111111 1111111111 n 11111111 m1 111m m11nn11nn11n,,,m11111 trade -marks and designs. If you will 111 a Security Bldg., Santa m111111mmuu u1111uu11m111111111,,,mn,,,,11nunu will malte search of the Patent Universal Scenario Corporation, 223 your invention we promptly & Hollywood, California. Office records and advise you as to patentability. our charge Monica Western. Indian Goods for the service being $5.00. Prompt. efficient service with exnortenre. Bank PhetoplaY Idea -Original, for sale. Luceal Aseneio, moderate charges. Over twenty years Station D, Philadelphia. Pa. Indian hunting bows. $2.50. Indian relics. minerals. and commercial references. Talbert & Talbert, Registered r. O. Box 3814, 10e. C. Catalogue. thousand ortirles 552 McGill Bldg., Washington, D. 1111111111, 1u1111 11111u111111111111111nInm butterflies, archery. Patent Lawyers. 111111 m111111111111111 111,1, 1111111101111111 1,w1111n111,11,un111111 Indiancraft S. I. Company, 466 Connecticut, Buffalo, N. Y. 1. Patents. Send for free booklet. Highest references. Send model or drawing Printing 11111,,,,,11111111111.111,1111,,,,111111,,,,,11,,,11m1, Best resn'ts. Promptness assured. .,11,,,,, 1111,11,11,,,,,,, 1111111, 111111111111, 111 ,,,,111,,,1111111111111111111 for examination and opinion. Watson E. Coleman, Patent Outfits and Supplies Insects Wanted Attorney, 614 G Street. N. W., Washington. D. C. Print your awn cards. stationery, circulars, paper, etc. flies. Insects. Inventors write me ahsut patents. My fees payable Job Presses $12, $35; Rotary $150. Get Fuller. Washington, P. C. Complete outfits $8.85; ddl advertisement page1i 1270 monthly. Booklet free. Frank Print for others, big profit. All easy. rules sent. 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New for our Guide Books and "Record of In- Patents -Write model ventinn Blank" before disclosing inventions. Send -Ups. The greatest Correspondence Courses sold complete: one -third ps,'nu for Examination and Instruc- Attention! 50 Varuum Tithe Aoolc hack nr sketch of your invention Vacuum Tube Circuits ever brought under two orlres because slightly used; easy terms; money tions. No charge for the above informs thin. See adver- collection of diagrams will be schools end subjects. Write for special J. Evans & Co., 194 Ninth, ravers at such insignificant cost. These guarantee. Al Edu- tisement on page 1257. Victor catalogue which contains raw Free catalog. Co,rses bought fnr rash. Economy W D. C. found in the great "Basco soIltng'n», parts in a greater profusion than any other rater Service. 112O2, West 40th St., New York. materials and bring the inventor keeps." catalogue. in Lacey Patent -Sense. "The book Radio Company. i kIll lace! 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www.americanradiohistory.com 1270 Science and Invention for April, 1925 eammmmmmm,nana,,nmm,cmmnnmmmnnmmimnmamnammii®immmmmimnan Salesmen Wanted $` Brings you a Genuine TIRES WITH 500 NAIL Can You Sell? All -wool, union made, tailored -to- measure DOWN suits for $19.75. Universal Tailors. J99 Bedford Street, UNDERWOOD Boston. HOLES LEAK NO T Y P E W R I T E R AIR A Salesman wanted in every town or city within 25 miles A new -proof of a broadcasting puncture inner tube has been in- 10 station to sell Radiogem, the complete vented DAYS FREE TRIAL ïnrróá9 ad'd`leï á radio receiving set that retails for $2.50. With Radiogem by a Mr. K. K. Milburn of Chicago. In days you ara not satisfied with tide late model UNDERWOOD there is nothing else to buy outfit includes actual test it was punctured 500 typewriter rebuilt by the famous Shipman Ward -the the Radio- times without process. gem receiving apparatus, 1,000 -ohm phone, and aerial out- the loss of air. This wonderful new tube in- s fit. The cheapest radio outfit on the market -yet as prac- GREAT PRICE SAVING ooVi tical creases mileage from 10,000 to 12,000 miles and tory of its kind In the world by our money t f° as the most expensive. Big money to the right men. saving methods. Send $2.00 for sample outfit. The Radiogem Corp., 66R eliminates changing tires. It costs no more than West Broadway, Y. the ordinary tube. EASY MONTHLY PAYMENTS W°, N. City. Mr. K. K. Milburn, 331 West thato 47th St., Chicago, notice it while you enjoy the use of this wonderful machine. Sell Guaranteed shirts, factory to wearer. Big commis- wants them introduced every- sion where and is making a special offer to FREE n paid in advance. We deliver. Make $5.00 -$20.00 agents. BOOK OF FACTS w á s Pi daily. Write for our "Wonder Sales Outfit." Curtis Write him today. -Adv. of rebuilding typewriters and also valuable information Shirt Co.. 508 So. Wells, aboremut the typewriter industryboth instructive and entertaining. Dept. 22, Chicago. Distributor -Wonderful Pricing System for all stores. Course for men of ambition and limited t t to e . Absolute Protection I Immediate repeat sales. Possibilities Electrical Over men $10,000 yearly! Write Manufacturer, Dept. 9, 100 Boylston, Condensed course in Theoretical Act Today! Boston, Mass. trical ndOPracticalrElec- 5 tnclndte- Fortune Mail Year Distributors- Right Men! Sensational New Auto the close- Number Frame retails $3 only! Spreading like Wildfire! Engineering ly related Coupon Guarantee Exclusive Territory now. Promanco, 538 Trinity Bldg., subjects of Mathematics and Mechanical Drawing Boston. taught by experts. Students construct motors, install wiring. test electrical machinery. Course 1 1 1 1 1 1 1 1 1 1 1 1 1 complete a : 11 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 m111 n o o o 0 01111 i a e 1 o o o1 114 ,1 111 1 1 1 1 1 1 1 1 1 1 1 1 1 1 a a o, 1 ----- a o o o o 1111 m a n a n o a a o11 m, Shipman Ward Please sen9dome Stamps and Coins Aug. a of In One Year Company free boopk of facts. Prepare for your profession in the most 2184 Shipman Building explaining bargain offer. California Interesting city Montrose & Ravenswood Gold, quarter size, 27c; half -dollar size, 53c. in the world. Estab- Ayes., Chicago Columbian nickel and catalogue, 10c. Norman Shultz, Box lished in 1893. Free catalog. Name. 196, Coiarado Springs. Colo. BLISS ELECTRICAL SCHOOL 214 Takoma Ave., Washington, St. and No Stamps 100 All Different 3 cents. S. I. Quaker Stamp ryt D. C. City State Company, Toledo, O. You'll get profit and pleasure collecting old. coins. Send Make X100 Weedy -sell RADIO 106 for genuine old coin and large coin catalog. This is Demonstrate Once Results Mean Sure lust a get -acquainted offer. Send today. You'll be de- - Sale Makes Autos Go 49 Miles lighted with it. 11. Max Mehl, Numismatist, Dept. N, Coast to coast,lowest prices,attrac- Mehl Building, Fort Worth, Texas. Largest Coin Firm thee four -tube instrument $39.50. In U. S. Big commission to you. Exclusive On Gallon of Gasoline territory An amazing new device has been perfected by James A. 500 Mixed Stamps from 40 different Countries, Aus- to proven salesmen. Ter- May, of 2567 Lacotah Bldg., Sioux Falls, So. Dak., that tralia, North, Central. and South America, Russia, Africa, ritory going fast, write today for cuts down gas consumption removes all carbon, prevents China, Japan, British, French Colonies, War issues, etc., large illustrated book No. 100. spark plug trouble and overheating. Many cars have made also 500 stamp hinges, pocket approval hook, perforation Don't fail to name your county. over 49 miles on a gallon. Any one can install it in five gauge, and 3 United States stamps issued before 1870, all minutes. Mr. May wants agents and is offering to send 25c. ARvd. Inc. one for Biggest bargain ever offered, satisfaction guaran- ,1e Washington Chicago, free to one auto owner in each locality. Write him today teed or money back. Hussman Stamp Co., Dept. SI. St. nl. Louis, Mo. Saes e1111111111111111a11aa111,1111111111111111111111111/an0e111111111111,11111111,111 a111=M11, Big To the Stamps for Collectors Profits

$1.00 worth of Stamps for 3c. Hull, 16 West 101st, Radio Dealer New York. Free 1000 different stamps for selling 30 packets sachet Let us explain how you at 1Oc each. Hull, 16 West 101st, New York. SEND FOR THE INTERNATIONAL CATALOG can make the sale of our Our net price list. Typewriters Full line of auto bodies publications a worth while, and accessor- Typewriters, all standard makes. $10 up. Fully guar- ies for Fords well paying part of your anteed.. Free trial. Write for complete Illustrated lists. at Wholesale Northwestern Exchange. 121 N. Francisco Ave., Chicago. Prices. Save business. .umnmimmmmm,m,immm,mnammammnn big money on mmimnm hosties by buying Wanted Direct from Factory. Write now and prepare FOR FORD -Prices from $27.85 up. Factory to consumer direct-Pay only One Profit for the Winter and Spring Detectives Earn Big Money. Work home or travel. Ex- International Body Works, 914 W.Ohio St., Dept.4,Chieago,lll. perience unnecessary. Write, George Wagner former Govern- trade. ment Detective, 1968 Broadway, N. Y. AGENTS 500% PROFIT Experimenter GENUINE GOLD LEAF LETTERS Ventriloquism Guaranteed to never tarnish. Anyone can Publishing Company put them on stores and office windows. Ventriloquism taught almost anyone at home. insult cost. Enormous 53 Park Place New York City Send 2e stamp today for particulars and proof. Geo. W. demand, large profits. Paul Clark Smith, Room M -949, 125 N. Jefferson Ave., Peoria, Ill. says: smallest day $28.70. R. L. Reel made $920 in two months. Write today for free sample and liberal offer to general agents. N. Y. Traffic METALLIC LETTER CO., 403 N. Clark Street, Chicago here's the LITE that Cops Use It BOTH RADIO DEALERS WANTED leaves hands free -Watch at BIG DISCOUNTS ON for every purpose, and it's a warning light, too St. Crossings STANDARD PRODUCTS The only light of its kind. W. C. BRAUN CO Wear it like awrist watch. 32 -40 S. Guaranteed for two years. Clinton St.. Cticago Longest battery service For ASK DEPT. 104 FOR DEALER CATALOG Brightest light of any flash light on the market. Every Made of the best available materials. Lights pit /lout Home delivered tom Tree a switch or button, by for 30 days trial on approval. Your gravity Endorsed by N.Y. Use choice of 44 Styles, colore and sizes of City Police Dept. and many the famous Ranger Bicycles. Express pre- other organizations where paid. Bicycles $21.50 and up the dependability of a flash ifdeahxd.i4anybaysand light means life or death çs rh la easily make [be bicycle aMonthearn ilia emallmonthly payments,. Tlines balfuarial Dmcea.Writéfoariraemerk Price as a able factory prices and marvelous offers. SAVE -A- LIFE complete trouble light, LITE [endd .. You can be quickly CIVILIAN MODEL $5 too cured, if you postpaid "The Light That NEVER Fails" and for First Aid to Safety First for Pedestrians. Motorists, Traffic . STAMMER Officers. Civilian model shipped postpaid complete with hat tery every flashlight Rend la cents for 2R8 -nage hook en Stammering and on receipt of price with order. if goods are shipped C O D , it Stuttering. "Its Cause and Cure." It tells how I deposit is required with order, and postage w ill he added to price purpose- leaves BOTH cured myself after stammering 20 yrs. B. N. Bogue, of shipment. Ordtr Lite now, use i1 lo days. If it's not all we claim return in good condition and your money will be refunded. hands FREE n i 81l5 Bogue Bldg., 1147 N. Ill. St., Indianapolis spend Spring, Summer $2 Agents Wanted -Exclusive Territories Open- Address Dept. A. WHY NOT and Fall gathering but - terflys, insects? I buy hundreds of hinds for collections. Some worth $1 to $7 each. RENOWNED ELECTRIC PRODUCTS INC. Simple outdoor work with my instructions, pictures, price -list. Send 10 cents (not 1841 BROADWAY Sole Distributors ' NEW YORK, stamps) for my illustrated Prospectus be- U.S.A. fore sending butterflies. Mr. Sinclair Bx.1424, Dept, Ba, San Diego, Calif.

www.americanradiohistory.com 1271 Science and Invention for April, 1925 GEORGIA-The Empire State of the South inspiring sculpture on Stone Mountain in the beautiful Blue Ridge Moun- Georgia, the state of hidden beauties, is featured in the MARCH issue last, a thousand and one hidden spots of natural beauty and Camper & Tourist. The tourist in Georgia obtains an education tains, and of Motor majesty that are waiting for the Motor Tourist. on the wonders of southern beauty that is unequaled anywhere in the & Tourist. southland. When you take your car, near or far, read Motor Camper a complete, practical and useful guide to the selection of equipment, the Georgia has Atlanta, the Chicago of the South, Savannah on the sea, It's of a route and the selection of good camps and camping comfort. the famous battlefields of Lookout Mountain and Chickamauga, the awe- selection Germott Publishing Co., Owners Licensed Publishers: The Experimenter Pub. Co., 53 Park Place, N.Y. On All Newsstands 25c the Copy Subscriptions $2.50 the Year

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www.americanradiohistory.com 1272 Science and Invention for April, 1925 A New Kind of Radio Magazine IQ REV/tips A ofDigest the Latest Radio Hookups 35` 35` THE COPY TIIE COPY Partial Contents Description of First of Issue Magazine

The Four -Tube Roberts One Hundred pages Receiver -How to make it. -each completely filled Construction of the new with constructional in- Pressley Super -Hetero- dyne. formation to satisfy the How to make the D -Coil most critical or ardent Set. An absolutely impartial Construction of the Ultra - enthusiast. dyne, L2. How to build the new review and digest of NO Priess Reflex. ADVERTISING The Browning -Drake Re- Hook -ups, Diagrams ceiver. O v e r 200 illustra- An efficient Low Loss set. The Two -Tube Harkness and New Circuits ap- tions of all kind and Counterflex. description. Modifying the Reinartz Receiver. pearing in the radio Constructional details of Size of magazine, 9 Britain's latest Multi- by 12 inches (Full stage R.F. Set. press the world over. - How to build a simple magazine size). One-Tube Receiver. This new magazine is dedicated to those of the radio fra- A Self -Neutralized R.F. ternity who wish to keep up -to- the -minute Handsomely printed Receiver. on all hook -ups, diagrams and new circuits appearing in A One - Control Regen- the radio press the cover in three colors. world over. We erative Set. are publishing this new material as quick- Magazine is written How to make an ly as it is available with original photographs and draw- \Ultra - Short ings. This magazine will be absolutely plainly throughout so Wave Receiver. impartial. New Hints to ra- circuits or information of constructional nature from every that everyone will be dio con- source will be printed, making it a true Review and Digest able to understand it structors, of the latest achievements in radio. etc., completely. etc. All articles will be of a constructional nature rather than of an instructional. Each and every article will be It is the only maga- illustrated and will contain complete data that will enable zine of its kind in ex- the constructor to build a radio set from the information therein. istence - the kind of a magazine In order to be absolutely impartial and unbiased, adver- so many tising of any kind will not be accepted. For this reason h ook - u p enthusiasts our magazine is selling for 35 cents. have been waiting for. BUY THE FIRST NUMBER FROM YOUR RADIO OR NEWS DEALER TODAY IF HE HAS NO SUPPLY ON HAND Don't forget to get Oie° WRITE US DIRECT- °a r o ly USING THE COUPON ON THIS PAGE. your copy NOW. °ft0ss °6 ^ 2 sP O . The Consrad Company á e4P 4. eP r 233 Fulton Street New York, N. Y. sP se °. q 9 Radio's Foremost Publishers ,rsGr dr0 0 4t- R Everything in Radio Books, Patterns and Diagrams

TIIE PERIODICAL PRESS, NEW YORK

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