Scienti Prizes

SCIENTI

IN PRIZES ELECTRICITY

Free Proof FOTYOU That You Can Equip for the Biggest Jobs m at home JUST think of being able to have this wonderful Shop Methods in Your Own Home book Free-the book that is bringing thousands big money in Electricity. There is no field in the world For I have devised a wonderful new system that that offers such great money -making possibilities to gives you the benefit of actual shop experience in your trained men as Electricity. Thou- own home. Never before has this sands are qualifying the new way by Methods been possible. But now, after fin- actual S. & H. Shop Type Train- Shop Type ishing my training you will be at ing. A few weeks during spare In Your Own Home home in the biggest electrical time in your own home, then you plant, in a sub -station, in a bat- are equipped to step right into jobs paying from $50 tery station, or with expert maintenance men, or on to $150 per week. Get this wonderful book, which automobile and tractor starting, lighting and igni- tells you just how you can do this. Sent free. tion work because you will have had actual experience, which means everything. for $3,000 to $10,000 Jobs Train Backed by Lincoln Inst. of Technology Don't stand back on account of education, experi- Electricity has ence, age, or location. No matter where you live, or This new system of teaching proved so successful that it has been highly recommended now doing, through my course you have what you are and endorsed by the great Lincoln Institute of Tech- a a pay the chance to become in very short time big nology. When you enroll you know you are backed "Electrical Expert." by a great institution. You receive free employment service and expert advisory service as long as you live. Free Outfit-Mail Coupon There is such a call for men now that we are giving outfit for experimental and practical Affiliated With Free an Electrical Institute of Technology - - - - home use if you enroll now. Think what it will mean Lincoln to leave forever the low pay rut to become a trained, Dept. D-2, 1422 W. Monroe Street, Chicago, III. managing FREE BOOK-FREE OUTFIT efficient Electrical Technician, capable of S. H. Engineering Co., and supervising ten or five hundred men on the big- Division of Lincoln Institute of Technology, Dept. D.2, 1422 W. Monroe St., Chicago, Ill. gest jobs; to travel, to be a man of influence-to have Please send me at once your big book, "How to Get the Better Jobs $10,000 per year. Find out now in Electricity," and full particulars of your course in practical Elec- a salary of $5,000 to tricity, your Free Outfit and your Free Employment Service Offers. how you can do this. You cannot afford to delay a 1 am not obligated in any way. right now for this wonderful Free Book Name day. Send Address that is pointing the way for thousands to big money City State in Electricity. The coupon brings you this book en- Give age if under 16. tirely Free, without obligation. Fill it out. Science and Invention fur April, 1924 1185

Be An Electrical Expert At $75 to $200 a Week Every up-to-date fellow knows what a future there is in electricity. Big pay-fascinating work on land or sea-rapid advancement in a field where jobs are ten times more numerous than trained men to fill them, where $75.00 a week is just a fair starter, where top notchers Full down ten thousand dollars or more a year-in a field, where any man if he wishes, can easily have a business of his own, have men working for him, be his own boss! But what the average young man does NOT know, is what a simple, easy, A -B -C sort of a job it is to get started. You Can Start Right Now! Yes, you. You don't need a thing you don't already have! You can read. You can write. You can figure. You can think. And in your breast is the fire of ambition-the desire to get ahead! All right, that's all you need-we can help you just as you are-just as we have helped scores, yes, thousands of other two-fisted young fellows determined to get out of the rut and into the electric field - into work that will be pleasant-easy-and all in your home, during spare time. Fascinating Home Study As You Hold Your Old Job With the help we will give you, you can slip right into one of these big pay-he-man jobs and never lose a day's work. After a few weeks' start, you can earn enough in installation and electric repair jobs alone to more than pay for the Course and lay a foundation for an Electrical Contracting or Repair Shop Business of your own. When the proper time comes, we will tell you the easy way to go about doing it. The Most Practical, Thorough and Condensed Electrical Course Ever Written This is the cnly home study electrical course that gives you the combined practical and theoretical training you must have before you can be a successful electrician without which you cannot succeed-with which you cannot fail. Written not by ONE man, with the narrow one-man viewpoint, but by 22 of the brainiest, most successful, electrical experts ever drawn from the field of practice and theory. Gives you the com- .1nr. a. n plete mastery of the subject-qualifies you as electrical expert to boss jobs-fits you right into the kind of a job you want-and does it in shortest time-at lowest cost-with the Most Binding Guarantee of Results Ever Offered! Satisfaction guaranteed or no sale! We not only SAY we can make you an electrical expert, we Guarantee ßiá AJitiLl itl If you are not absolutely satisfied when you have finished our Practical Electrical Course, we will refund Prac7tealElectricians every nickel you sent us. :Urn Big Pay Experimental Outfit Worth $30 Find out all about our Drafting Course Worth offer. Find out about the Another $30 who have taken FREEt Big Electrical Library Worth $2ffi , this course in preference to all others and MADE GOOD. Find out about the Electric Library-four elegant volumes-worth ;25.FREE but free. About the free Drafting Course worth another $30. The free Experimental and Demon- stration Otitfit, includirg a real, not a make-shift Electric Motor, Wheatstone Bridge, etc.-the most de scientific, high-grade and complete Experimental Outfit ever supplied with a Course in Electricity., Get all the facts without obligation, without expense! Just send the coupon! ' Electrical Own Your Own Coupon Electric Shop American School Dept. E-426 Drexel Ave. and 58th Street, Chicago American School, Dept. E-426, Chicago Please rush all information relative to your Course Ignition Esperta 'in 1r Electricity. This obligates e me in no way whatever.

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Vol. XI. tltttttt April, 1924 \)71`\ \ ` E Whole No. 132 \ \ \ No. 12

FORMERLY ,,,,,,,,1111,11,111,1,111111,11,1,1,,,11 ELECTRICAL EXPERIMENTER íllember dudit Bureau of Circulations

PUBLICATION OFFICE: EDITORIAL & GENERAL OFFICES: 18,430 Jamaica Ave., Jamaica, N. Y. 53 Park Place, New York City Published by Experimenter Publishing Company, Inc. (H. Gernsback, Pr -s.; S. Gernsback, Treas.; R. W. DeMott, See'y). Publisher of SCIENCE AND INVENTION, RADIO NEWS, and PRACTICAL ELECTRICS Taibre of Coneene5 loft- Apirill

POPULAR SCIENTIFIC ARTICLES "THE MIRACLE," :\ WONDER O1' MODERN EDITORIAL By II. STAGECRAFT By W. B. Arvin 1214 Gernsback 1195 HEARING THE SOUNDS OF INSECTS 1217 IS THIS PERPETUAL MOTION By C. Marshall 1196 By W. \V. Rodgers CONSTRUCTION OF SUPER -AIRSHIPS 1196 LATEST PATENTS By Ruth A. Krohn 1243 ANCIENT THE ORACLE-QUESTION AND ANSWER BOX.... 1245 CLOCKS By Charles Beecher Bunnell 1197 PATENT ADVICE Edited' by Joseph SCIENTIFIC MATING 1193 H. Kraus 1266 By H. Gernsback, Member American Physical Society A GAMBLER'S TRICKS EXPOSED-By Mark Mellen 1199 RADIO ARTICLES AWARDS OF $10013 MONTHLY PRIZES 120(1 A RADIO EQUIPPED CHURCH...By J. F. Odenbach 1231 TRAVELING ON A LIGHT WAVE 1201 SIMULTANEOUS BROADCASTING 1232 By Ernest Brennecke PORTABLE RADIO SET AND NEW LOOP THE MAX ON THE METEOR-PART FOUR OF SOME NOTES ON LEAD-INS A SERIES By Ray Cummings 1202 SEARCHLIGHT CAUSES FADING 12'13 DR. HACKENSAW'S SECRETS --NO. 28-THE By C. Doville Walker SECRET OF SIZE By Clement Fezandié 1204 SELF-CONTAINED PORTABLE RECEIVER WORLD'S GREATEST BRIDGE FOR "GOLDEN YOUR VOICE MADE VISIBLE 3513.!4 GATE By H. Winfield Secor 1206 EFFICIENT CRYSTAL RECEIVER.. By Gilbert Billin 1235 PREPARATIONS MADE FOR SHENANDOAH'S A CRYSTAL SET LOUD TALKER 1236 POLAR FLIGHT By Graser Schornstheimer 1208 COMPRESSION TYPE RHEOSTAT 1236 VISION VIA SOUND WAVES 1210 By Armstrong Perry ANCIENT METHODS OF RAISING WATER 1211 RADIO SET AND PHONOGRAPH COMBINATIONS 1237 By L. B. Robbins SELECTIVE RECEIVERS - FROM BEST TO THE TRANSIT OF MERCURY. By Donald H. Menzel 1212 SIMPLEST By A. P. Peck, A.M.I.R.E. 13,íc WEATHER LEGENDS AND PROVERBS 1213 IMPROVING THE SINGLE CIRCUIT TUNER 124' "THE MIRACLF \ WONDER OF STAGECRAFT 1214 By Jack Kay By W. B. Arvin RADIO HAZARDS PROBLEMS OF AIRSHIP CONSTRUCTION 1215 RADIO ORACLE 124113411 HEARING THE SOUNDS OF INSECTS 1217 RADIO BROADCASTING STATION CAL L By W. \V. Rodgers LETTERS 1248 MEASURING STAR SPECTRUM HEAT 121)1 RADIO WRINKLES Edited by A. P. Peck 1264 By Dr. C. G. Abbot Tills MONTH'S NEW DEVICES 1219 CONSTRUCTOR ARTICLES TIMELY TALKS ON TIMEPIECES 1220 By Samuel Bernard MAKING A TRACEOGRAPH.....By Constantine Troy 1225 MAGIC FOR EVERYBODY. By Prof. Joseph Dunninger 1221 SPEED REDUCTION GEAR 1225 EVERYDAY CHEMISTRY By Raymond B. \\'aides 1222 NATURE EFFECTS IN THE THEATRE 1226 EASILY PERFORMED MATCH TRICKS 1223 By L. B. Robbins By Walter B. Gibson A BALD HEAD WIG By Charles T. Allen 1227 THE HEAVENS IN APRIL..By Isabel M. Lewis, M.A. 1224 USES FOR HARROW DISCS By L. B. Robbins 1227 PRIZE CONTESTS MAGNETIC LINES ILLUSTRATED 1227 l'RIZE WINNERS-$1,000 AWARDS IN OUR By Clarence Ray1228 MONTHLY CONTEST 1200 SILHOUETTE SHADOW PICTURES HOW -TO -MAKE -IT DEPARTMENT $30.00 IN By A. Gruntal PRIZES MONTHLY - 1229 SCIENTIFIC HUMOR-PRIZES FOR BEST JOKES 1244 CHEMISTRY ARTICLES EVERYDAY CHEMISTRY.... By Raymond B. Wailes 1222 AUTOMOBILES -PHIS MONTH'S NEW DEVICES 1219 ASTRONOMY ARTICLES 1261 MOTOR HINTS THE TRANSIT OF MERCURY. By Donald H. Menzel 1212 re ELECTRICITY MEASURING STAR SPECTRUM HEAT 1218 By Dr. C. G. Abbot SCIENTIFIC MATING ByH. Gernsback 1198 THE HEAVENS IN APRIL 1224 VIA SOUND WAVES 1210 VISION By Isabel M. Lewis, M.A re- ,,,1111,,,1111aea,,,a,11111a1,1,l,,,,mln,,,,,m,mtnit , 110W TO SUBSCRIBE FOR "SCIENCE AND INVENTION. Send your lee and Bland possessions For foreign an re to Experimenter Publishing or Canadian subscriptions we halite, address and rem!tt Co., 53 Park require 50 cents in addition to the subscription for Place, New York. Mention the name of the magazine you are ordering. age charges. price additional post- We also publish RADIO NEWS and PRACTICAL ELECTRICS. CHANGE OF ADDRESS. Notify us as far RATES AND TERMS. The subset iption rate for SCIENCE AND IN- requires in advance as possible. It saveral weeks to make an address change on our records. Always VENTION is $2.50 per year (12 numbers.) When remitting 3o so write Ilea 'Ir, giving your old address by check, money miler or registered letter, if cash is enclosed. Avoid as well as your new. ON EXPIRATION sending cash through the mail if possible. Subscriptions for less than of your subscription we enclose a renewal blank in our one year are not accepted. Subscriptions may he made in eombl'tation last number to you and notify otherwise. order you Unless we receive your with RADIO NEWS or PRACTICAL ELECTRICS with considerable sav- for a renewal, with your remittance, we stop our delivery to you ing. Send postal for special rates. Subscriptions start with the errent expiration. on issue, unless otherwise ordered. COMMUNICATIONS to us should always hear your full POSTAGE. We prepay postage in all parts of the United States, 51ex- and when possible the name address number which appears on your wrapper ever, In tin

SCIENCE AND INVENTION is published on the 25th of each month. cannot be returned unless full postage has been included. Is $2.50 a in U. S. tributions ALL accepte,) con- There are 12 numbers per year. Subscription price year are paid for on publication. A special rate is paid novel and possessions. Canada and foreign rnuntries $3.1)0 a year. i1. S. coin as meSCIENCEid photographs far experi- copies, 25 arentered well as i1. S. Stamps accepted (no foreign coin or stamps). Single INVENTION.NTION.ty itMonthly. ase3seco d -class cads. A sample copy will be sent gratis on request. Cheeks and money at Jamaica, N. Y., Post matter cents Office, under act of Congress of March :t, 1079. orders should Le drawn to order of EXPERIMENTER PUBLISHING CO., Title Registered at the Patent Office. Copyright, 1929, address notify us promptly, in order that copies are New York. The by E. P. Co., Ire.. Inc. If you change your Contents of this Magazine are copyrighted and must not be not miscarried or lost. reproduced without giving full credit to the publication. All communications and contributions to this journal should be addressed to SCIENCE ANI) INVENTION is for sale Jamaica Avenue, Jamaica, New States at all newsstands in the United Editor, SCIENCE AND INVENTION, 18,430 and Canada; also at Brentanó s, 37 Avenue de l'Opera, Parie. Member York, or 53 Park Place, New York City, N. Y. Unaccepted contributions of the Audit Bureau of Circulations, New York City Western Advertising Representatives. Pacific Coast Advertising Representatives. Kansas City & McClure, A. J. Advertising Representatives. General Advertising Dept., Finucan Nor -is Hill Co.. George F. Dillon, 720 Cass St., Chicago, III. Hearst Bldg., Sen Francisco, _)'11 53 Park Place Calif. Republic Building. Kansas City, Mo. h. 7fr Q 1186 Science and Invention for ,1pril, 1924 1187 A New and Mysterious Happiness A Startling and Sensational Discovery A Mysterious Secret

NO wonder men and women every- exercise with- every known and conceivable disease. where are excited over this start- out exercise ; This startling natural law is guaran- ling new discovery of a Universal all of the teed to give perfect health. Law and Power by which a new mean- benefits of If you are not enjoying life to the full ing is given to every pleasure, function, conscious -if you are in any way handicapped deep breath - action and to every joy, gratification and -if you are not in possession of all of i n g without happiness. the powers of mind and body to the conscious highest degree, you it to yourself, Who could resist becoming excited if deep breath- owe the pleasurable realization of life in all to at once procure for yourself, free of ing ; the full charge, revolutionary of its phases were multiplied and in- and complete this natural law. tensified? benefit of Through this supreme natural law anyone may have the same health and vi- will become over this every vita - You, too, excited tality of a lion or tiger. great discovery because it will give you mine and a new thrill-an intense and lasting organic iron Remember that the demonstration and thrill. without drugs results are immediate and free. or dieting ; all a This powerful This new and startling discovery of of the bene- natural law transforms life, health the gloom of disease supreme natural law of and fits of medi- into the bloom of pleasure is joyfully revolutionizing the cine and health, as the rays of the spring sun lives of thousands of men and women drugs without transform the dead soil into a "sea" of all over the world. It is bringing them medicine and luxuriant vegetation. It is destined to revolutionize a new kind of pleasure, happiness, drugs; all of human health and happi- health, strength, confidence, energy and t h e benefits ness-Humanity. power of personality and success. It of auto -sug- This natural law is most marvelous, is giving them such marvelous energy gestion, hyp- most simple, most subtle and most of mind and body, and they enjoy life notism a n d powerful. It is the Law of Creature so fully, so intensely, so dominatingly, psychology without auto -suggestion, Power. and so thoroughly that the old life to psychology ; all of the hypnotism and Remember there is which they were accustomed appears every nothing active to benefits of dieting, and other do, nothing to study, totally inferior in every respect. device assistance nothing to believe, kind of treatment, or no time to waste, The possession of this new and mys- without these treatments. no habits to give up, nothing to lose-there is no terious natural law gives a new idea of mystery- this natural law, any- it is merely Natural Law. how truly vital, alive, joyful, healthy Chrough amazing one can rid self permanently of every and happy a human being can be-how You would not be without this secret human weakness ; no matter who you easily one can he overflowing with life. if you could are, this Natural Law can demonstrate imagine how delightfully energy, bubbling vitality and the fire of transformed your life would to you that you do not vet know the be through triumph. Although thoroughly natural the possession of this new and deeper and simple, nevertheless it accomplishes full meaning of joy, happiness, pleas- realization vitality gratification. of happiness, pleasure, joy seemingly impossible results without ure, and and gratification. sacrifice, active effort or cost. This Natural Law is ready to give you This secret is offered to you absolutely a new realization of the meaning of life A new life with a unique thrill is yours free. There are no "conditions" or when you possess this newly discov- and enjoyment. "strings" attached to this offer. ered natural law of supreme life, health This extraordinary and Universal Law and pleasure. It is no longer necessary Special Note-Swoboda has a price- does not require you to actively do less secret for for one to spend money for treatments re- every human being who anything or give up anything. It wishes to be happier, healthier, and drugs and dieting and books and quires no exercise, no time nor con- more vital and successful in a new degree. systems and cures and pills and devices. scious deep breathing-no stretching. because perfect and supreme health and dieting. drugs nor medicines. are absolutely free through this life This natural and supreme law must not marvelous natural law. ALOIS P. SWOBODA, 1241 Berkeley Bldg., he confounded with hypnotism, auto- 21 West 44th Street, New York City. Why be weak, why be ill, why be fat, psychology, suggestion, spiritual Send me FREE the Swoboda Natural Law of why he thin; when you may absolutely science, psychic science, mental science. Supreme Life and Health. free, become in every way perfect and nor with electricity or any other To help cover the cost of publishing and mailing. I enclose postage. (Not more than ten supreme through this sensational natu- method-mental or physical-ever de- cents, please.) ral law? vised in the past. This extraordinary natural law yields No self -hypnotizing phrases to repeat Name (Write Plainly) amazing nerve force, amazing energy, -no yielding, no recession, no giving amazing vitality and amazing power up of anything, nothing to study, noth- Address of every character of mind and body ing to actively practice. no books to City State -a new and superior life. buy, nothing to memorize, no self-de- Through this sensational natural law ception-nothing but truth-reality- Special Note-Many individuals who have obtained this secret claim it is absolutely price- you may have all of the benefits of Natural Law. Perfect health cures less-worth millions. 1188 Science and Invention for April, 1924 j

Electrical Construction Electrified Railways Public Buildings Are Utter a Big Field Big Users of Electricity Needs Trained Lspens j iiiï/////////%iiiaiiiiaiiiií/////////iiiiiaa%///// EI,ECTRICITY FJectrical experts Earn The Men in the Picture Be a COOKE Trained Below is a picture of L. L. Cooke. Chief Engineer, and his Engineering Stall, engaged In Students' Consulta- tion Work. Through this Free and un- Electrical limited consultation service, nine trained Expert and competent engineers help the students of this school with the problems Now you earn $20 or $30 or $40 a week. In the same six days as that come up in their work-not only while they are studying but for years an Electrical Expert you can make $70 to $200 and make it easier- afterward-Just as long as they care to use it. Think what this means to you- not work half so hard. Why, then, remain in the small -pay game, having a group of engineers advising and helping you-without costing you in a line of work that offers no chance, no big promotion, no big- one penny. income ? Fit yourself for a "bossing" job-Be a Cooke Trained This is only one of the features of the unbeatable "Cooke" Serv- Electrical Expert. ice that backs up "Cooke" Train- ing. Today even ordinary Electricians-the "screw driver" kind-are making money-big money. But it's the trained man-the man who knows the whys and wherefores of Electricity- the "Electrical Expert"-who is picked to "boss" the ordinary Electricians-to boss the Big Jobs- the jobs that pay $3500 to $10,000 a year.

) 7ke!'COOKE" Trained Man Science and Invention for April, 1924 1189 7, / j

A.rdrn-F.leetriC Plants lauge Power AMenAreGee Plants Need Needed ml I 1 Being BBuiltwhereEcerv Experts to Operate Them //////iiiiiiiiiiiiiiiiiiiiiii/////% j for BIG PAY $3500 to $10,000 aYear Get in line for one of these "Big -Pay Jobs" by enrolling now for my easily learned, quickly -grasped, right -up-to-the-minute, Spare -Time Home-Study Course in Practical Electricity. Some Features of Cooke Training Age or Lack of Experience That Make Success Certain 1. Praet meal Mane,-Maldog Instruction-no useless. high-sounding theory. No Draw -Back 2. Free Electrical Outfit-Finedt outfit ever sent out for home experiment and practical use. You don't have to be a High School graduate-it isn't even necessary that you 3. Free Unlimited Employment Service. (Helps you should have finished the grades. As Chief Engineer of the get a gaol lob. i Chicago Engineering Work,. 1. Free Unlimited Consulting Service. (No chance I know exactly the kind of training you need, and I will give you that training. NI, to get st erg at anything, while studying or course in Electricity is the most simple, thorough, successful and practical in existence, afterward.) and offers every man, of age, 5. Free Subscription to Monthly regardless education, or previous experience, the chance zine. Engineering Maga- to become in a few short months, an "Electrical Expert," able to make front $70 to Free $200 a week. use my 7.f. Extra Courses Fret Radio-ElectrtealtoDrafting- Busineas-Autcmtobile Electricity-Mine Elec- tricity and Special Lessons on Health and Thrift. Earn While You Learn 8. Spare Time Work-Special earn -while -you lessons. -leant With me you do practical work-at once. In my first few lessons I show you n. Reduced prices on all Electrical how to make money doing Electrical work in your spare time. (Over half of my Supplies. students are paying for their course in this way.) I show you also how to get started Ie. Cash Refund Guarantee in business for yourself, and then help you to get started. Bond. These features are all explained in my big Free Book- the Vital FREE-Electrical Working Outfit-FREE Facts." To do spare time work you'll need tools, rte. These i give you- Free-a whole kit including measuring instruments, a real electric motor (no toy and other things -the greatest value ever given by any School. Your Satisfaction Guaranteed by a Million Dollar Institution I absolutely guarantee to return every penny paid me in tuition if, when you have finished my ('ourse, you are not satisfied in every way with my instruction. And hack of utr. in my guarantee, stands the Chicago Engineering \Varks, a million dollar in-Iit ullll. Nothing Like "Cooke" Training Anywhere "Cooke" training is different because it's the most practical and most successful. It's best because it's backed up by the greatest Service to students ever known. it's L. L. COOKE, this Service, plus "Cooke" training, that makes the "Cooke" trained man the "Big Chief Engineer, l'ay" man everywhere. Become a "Cooke" Trained Man yourself, and earn $12 to Chicago Engineer- $30 a day-$70 to $200 a week-$3500 to $10,000 a year. ing Works, Dept. 24, 2150 Lawrence Ave., Investigate! Mail Coupon Chicago, Ill. Dear Sir-Send at once Got the Vital Facts. Let me send you free my big, new book on The Future of the "Vital Facts" containing Electricity. Let me tell you more about the big demand for `Cooke" trained Electrical Sample Lessons, your Big Book, experts. Sign and send me Coupon below. and full particulars of your Free. Outfit and Home Study Course--' all fully prepaid, without obligation L. L. COOKE, Chief Engineer on my part. Chicago Engineering Works, Inc. Address City and State 2150 LAWRENCE AVE. Dept. 24 CHICAGO, ILL. Occupation Age is the"BIG PAY"Man na 1190 Science and Invention for ,lpril, 1924

"CONSRAD" Pattern No. 9 Make Your Own ST 100 Receiver -> The S. T. 100 receiver employing a circuit devised by John Scott -Taggart of London, has proven to be one of the most efficient sets of reflex variety for broad -casting reception. While only two tubes, a crystal detector are used, the energy amplified of incoming signals is powerful enough to operate any type of loud speaker without additional amplification. struction pamphlet giving complete de- The quality of reception will astonish those who tails as to the parts required, tools are familiar with the performance of other circuits. needed, and even how to tune. Another important feature is that the set tunes All these are contained in a two-color sharply, which is one of the utmost requisites of an heavy manilla envelope, 91/2x12". ideal receiver. The packet consists of blue prints for drilling the panel, wiring the apparatus, and a four -page in- Price 50c Consrad Cloth Map of U. S. Broadcast Stations The Consrad Radio Map is different from all other maps in that it is printed on CLOTH and with proper care will last a lifetime. The Map measures 17x22" and contains a special

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The five Lecture Books with To own them is like having a trained engineer or over 100 graphic drawings give you the knowledge instructor at your Side. answering ttuestionS, point - to intelligently buy, design, build, operate and log the way. No matter what your interest in maintain radio receiving apparatus. Tells you how radio, take advantage of this attractive special offer $1.25 to locate and correct troubles, how to make your and be the owner of lids fine set of books. This set can be obtained at your dealer's or direct from us on receipt of $1.25. If you prefer we will send it C.O.D. and you can pay the pbstman on receipt. The Consrad "Making Your Own" series consists of plans for the construction of the most popular radio circuits and are arranged so that anyone can construct a receiving set as easily as a woman can sew the simplest dress. Blue prints are furnished for drilling the panels and wiring the parts and a four -page pamphlet contains complete instruction even as to tuning. Each pattern is contained in a two colored heavy manilla envelope 91/x12" 50e and sells at No. Other Titles in this Series: 1 How to Make a Short Wave Regenerative Receiver 50c 2 How to Make Detector and Amplifier Units 50e 3 How to Make a Radiophone Crystal Set 50e 4 How to Make a Reinartz Receiver 50e 5 How to Make a Reflex Receiver 50e 6 How to Make a Cockaday Receiver 50e 7 How to Make a Neutrodyne Receiver 50e 8 How to Make an Autoplex Receiver 50e Packet B 20 Radiophone Diagrams with Supplements 50e C 14 Radio Formulae and Diagrams 50e D All About Aerials and Their Construction 50e E Radio Amateur's Practical Design Data 50e ..... For Sale at All Reliable Radio Dealers á.=" "".,alNLiiNo1 iF41- HOW to make or - THE CONSRAD CO. Publishers and Sales Agents 233 FULTON ST., N. Y. CITY Science and Invention for LI pril, 1924 1191 How to Invent What to Invent and What to Do About Protecting and Selling An Invention LTHOUGH the fact has been . uni- you. Get the advice and the help of the -How to develop your imagination versally recognized that ' Inven- fifteen famous inventors who -How to develop your ideas tell you the tion is governed by a few -simple, -How to get the facts you need for secrets of invention which you MUST! easily acquired, fundamental prin- inventions know to be successful. eiples, no one ever thought of putting -How to keep legal records of ideas This is the first course in practical inven- these principles in black and white so -How to use scientific principles of tion been devised. that mechanics that has ever In simple, everybody interested in invention could -How to avoid wasting time on im- easy -to -understand language you are told read them. In spite of the fact that practical inventions how successful inventors work; you learn Thomas A. Edison made his famous state- -How to apply for a patent how to think along - inventive lines, you ment that invention should be taught as a -How to organize a company learn the short-cuts to successful inven- science, thousands of people continued to -Hew to protect your rights tion; you learn how to use the secrets of work blindly, doggedly, haphazardly to --How to market a patent invention that convert a simple little idea and hundreds of other vitally important facts perfect their ideas. which EVERY successful inventor knows into money. But now anyone can learn how to in- and uses. No one step in invention has been omit- vent. Fifteen famous inventors have at ted. Everything you want to know about last given to the world the laws and prin- invention-developing your ideas, secur- ciples of Inventive Science. They. have problem. So, although you may never ing information you need, how to apply shown every ambitious man and woman have thought of it in just this way every for patents, how to protect your rights, how to invent. They are teaching Inven- time you solve a problem in your daily how to sell your invention-are taken up tion exactly as other people are teaching life-at home, traveling, or in business- step by step, so that when you have com- law, medicine, bookkeeping. Instead of you are an inventor; you use the principles pleted the course you have a wealth of in- spending years groping blindly, instead of of thought and action which govern the formation worth thousands upon thou- wasting your time in useless, Science of Invention! sands of dollars. heartbreaking drudgery, you You can see, therefore, how learn how to complete your easy it is for you to develop FREE-New Book on ideas quickly and what to do your natural instinct to "fix Inventive Science about them when they are com- things." The same processes of pleted. You learn how to think thought that almost instinctive- A wonderful new book has just come so you are sure to succeed. ly told you to fix a rattling win- from the press that tells you all about the dow with a wedge can be so well Science of Invention. It tells you how to developed that you can learn to avoid the pitfalls that have brought failure Everybody Invents invent other things almost as to thousands of would-be inventors. It For a long time it was com- easily and quickly. You know, tells you how to learn the secrets of prac- monly believed that every in- too, that every invention is tical invention, which famous inventors vention was a matter of pure made only by thinking inven- discovered only after years of heart -break- result of some happy tively. And every inventor is ing effort and discouraging mistakes and luck-the Raymond F. Yaks, inspiration that suddenly who with fourteen agreed that the principles of In- it tells you how to do this in only fifteen, other famous inven- Science are so simple, so minutes of your spare time each day. flashed though a man's brain, tors, now makes it ventive This easy for you to learn easy to learn that any one, re- fascinating book will be sent to all those and which made him fabulously how to invent in rich without the slightest ef- your spare time at gardless of training or education, who are genuinely interested. Get the ad- fort or thought. But you can home. can develop himself to become a vice of those fifteen famous inventors. Let prove for yourself that this is successful inventor! them tell you how you can easily' learn the. not so. You can prove for yourself that With every new advance, with every secrets of successful invention. Send for invention is the result of thinking and ac- new discovery that the world experiences, this Book today as only a limited number tion along definitely exact, scientific lines. more problems are coming up-and more are available for free distribution. Send Suppose when you went home tonight, inventions are needed to solve these prob- the coupon below NOW, or a letter or pos- you found a window rattling, Through lems. Now, as never before, are new inven- tal card will do. There is no cost or obliga- your mind would flash, almost instinct- tions wanted, and the world will pay a for- tion. This bureau is not connected in any ively, a regular order of thoughts which tune to the man or woman who gives it just way with patent attorneys or manufac- characterize the conception and com- one of the inventions it needs. turers. Our only work is'to help ambitious pletion of every invention the world has Even little ideas can bring you a for- men and women to develop their inventive ever known. First, you would recognize a tune. Eberhard who invented the rubber ability-to become successfulinventors. problem to be solved-the rattling of the on the end of a pencil, has been paid hun- window. Then you would think of several dreds of thousands of dollars for his simple Bureau of Inventive Science the metal principles of science or mechanics which idea. The 'man who invented Dept. 74, Wisner Building, Rochester, N. Y. would solve your problem. You might tip for shoelaces, the man who conceived the idea of the "humped" hairpin, the man think of the scientific fact that if you BUREAU poured water on the frame the wood would who developed the metal tape measure; OF INVENTIVE SCIENCE swell and tighten the window. You might all have achieved success and wealth as Dept. 74, Wisner Building I think of using a nail. But what you most great or greater than the inventors of large I Rochester, New York probably would do would be to use the machinery. Please send me lour free book, "The Science of oldest mechanical principle known to man, how to invent at home 1 Invention." the wedge. Learn I. I What Invention Is If you would like to develop your natu- I Name Age I making ral inventive ability along money I I Brought down to its simplest terms, lines, instead of trifling with ideas-if you I Addre ss I that is exactly the way every invention has would like to DO something about your 1 been made-combining two ideas; a prob- ideas instead of letting someone else lem which must be solved and-a--fact-of- patent and -market them ahead of -you,- let LCity State mechanics or science which solves the this great Course in Inventive Science help J 1192 Science and Invention for April, 1924 Two New E. I. Books for the Radio Fan

History and Operation of the Vacuum Tube t.VEP09EIv1LP5 teNP.Pv Nn .9 By PROF. J. H. MORECROFT Associate Professor of Electrical Engineering, Columbia University Edited and Approved by MAJOR GENERAL GEO. O. SQUIER, Chief of the Signal Corps, U. S. A. This book serve: an interesting study of the fundamental principles, historical evolution, and practical application of the vacuum tube as used in radio apparatus of every description. Since the vacuum tube is one of the most important parts in the modern radio set, and has been largely responsible for making present-day radio entertainment possible, this book has been entirely devoted to the subject of that one particular instrument. it is written in simple OM EAST COURSE language ire HOME RADIO everyday with all technical terms thoroughly explained so as to make matters easily understood by everyone. . . ` `9"h. THE E.I.CO. cw.o9« C..r, The book contains chapters on the phenomena of vacuum tubes in general; the operation of vacuum tubes as detectors and amplifiers; and the junction of the vacuum tube used in various transmitting and receiving circuits, etc., etc. 52 pages printed in legible type; 24- illustrations and diagrams; bound in two-color cover; 51/2 x size 71/2 inches ; pr ice, 25c. All About Radio Parts By THOMAS W. BENSON

This book gives an extensive description of the various parts used in all types of receivers, especially explaining the features of certain apparatus and circuits. It also describes why the different parts are used and how they operate. There has been nothing overlooked. To begin with, the book tells how radio waves are collected by means of an aerial, giving details of construction of different types and their advantages. Then detection is explained and various types of crystal and vacuum tube detectors described. Amplification, including regeneration, radio and audio frequency, is simply told. This very instructive book will prove to be of great value in the hands of anyone interested in radio as it is very explicit and thorough. Contains 52 pages, 36 illustrations and diagrams; bound in a two-color cover-size 51/2 x 71/2 inches. Price, 25c.

HOW TO MAKE cJ RADIO -PHONE Other Books in the "Experimenters' Library" '." RECEIVING SETS

MSOw7. No. 2-How to Make Radiophone Receiving Sets 25c No. 3-Radio Questions Answered 25c No. 4-Radio Frequency Amplifiers 25c No. 5-Loud Talkers and How to Build Them 25c Ka"t73 TUNE :YOUR item S9 No. 6-How to Tune Your Radio Set 25c No. 7-100 Radio Hook -Ups 25c

The "Experimenters' Library" is being increased at the rate of at least one new title each month. Every book is written by an RADIO rREQUENCY AMPLIFIERS 1. MDS MMKC 155M authority and in language easily understood by everybody.

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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 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 8,000 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. yoa001101111r 111%4:: The N. Y. E. S. gives a special Automobile Ignition Course as an advanced lreelefll111e11 Nashi training for Auto Mechanics, Garage Men and Car Owners. m.r,3 enrt11M 1Esss 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 me your 64 York -page book.

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3111111,1111 111,11 iiiii 11111.1iim111111416,11111111111111,1111.111111111 ,,M,.,,,,,111,,,1 ...... m,,,.,,,,.,,.,.,,,,,,,,,,,,,,,,,,,,,,,,. ,\\\, \ \\,,,,,,,\ y \\:\\e \\\\ '\e\ /\., APRIL Volume XI 1924 = , Whole No. 132 No. 12 i..,,,.,... r\. ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,11111,,,,,,,,,,,,,,,,,,,,,,,,,,,,, e\\\\\a\\°p°Q\\\\\ H. GEItNSBACK, 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

"Those Who Refuse to Go Beyond Fact Rarely Get As Far As Fact" - - HUXLEY ,,,,11,,,,,,,,,1,,,1,.1,111,,,,,,1,,,,,,,111,,,,,,,.,1,,,,1,1 ,, ,1, ,,.,,,,, 1.,,,,.,,,,,,,,1,,,,,,,,.,1,,,,1,,,,,,,,,,,,;,,, 1, 1,1,,,,,,111,,,111,11111,,,,,1,,.,,,,,,1,,1,,,1,,111,1111111111,1111111 1,,,,111,1, 1,,,,,1,,,,,,,,,,,,,,,,.,,,,",,,,1,1,,,,,,,1..,,,,,,,,,,,,,,111,,,11,1,11,,,,1.,,,,,,.11 lice In 5oune -Land by N. NSIGACK HE other day I called on Alice-you know, the same heard, very pleasing to our ears. But commercial electrical Alice whom you accompanied to Wonderland years vibrations are slow. So we entered the house and I took Alice ago. She had not changed one bit and was as bright near to the big steam radiator in the living room. I set the and as inquisitive as ever. sonoscope to the heat vibrations which go from 70 to 281 I pulled out fron my pocket two attachments, like little ear- trillion vibrations per second. The heat of the radiator gave muffs, made of bright metal and glass and which were to be out a very shrill whistling sound much higher than the electric worn over the ears, not unlike a pair of radio head receivers. high tension line and the sounds rose and fell due to the fact "These," I said to Alice, "are Sonophones, a new invention that the heat in the radiator was not even. I then adjusted of mine that makes all vibrations in the sonophone for 562 trillion vibra- 1111"'"11111"""'^"""""""""""""""""""1111" the whole world audible to your ears. tions per second-light vibrations- bade Alice to step out into the As you know the human ear can hear and I BELIEVE 1 BELIEVE sounds only beginning at about 16 sun light. A tremendous roaring ¶ THAT ¶ THAT the more times` vibrations per second running up to sound was heard immediately. We have not changed _ Be- were now hearing light waves, the you learn, the less much since Tutank- = slightly above 32,000 per second. hamen. low 16 vibrations such as certain low sunlight giving the vibrations. "Why you know. basso organ pipes, the average human is the sound not steady? queried ear can hear nothing. Above 32,000 Alice, "for the sun light surely is in steady." I explained to her that, due to the sun spots, varia- such as very high pitched whistles which we can produce of sun light are produced and our radio instruments, the same ear hears nothing further. tions in the strength the certain light's intensity somewhat. For "We will now take a trip into sound -land where we will atmosphere also changed the reason we hear that peculiar swell such as you hear from hear sounds of the low and high vibrations." that big tremendous sound, great in volume "This sounds interesting," said Alice, who loves puns. a organ pipe. It was a and very pleasing. The sounds were much higher than those I clamped the sonophones over Alice's ears and a like pair of the steam radiator. over my own. A slight adjustment brought. us down to sound We next took a jump up to one quintillion vibrations as low as two per second. We watched """""""""""""""""""' vibrations, in figures 1,152,921,504,606,846,976. a big eagle over head while he was flying towards = Alice could not understand that there could be so The note made by his wings was easily I BELIEVE us. many vibrations per second. I, however, led her audible; not just a flapping noise, but a real low ¶ That in order to into the laboratory and started an X -Ray tube to sort of a hum. But as low vibrations did not hold become an inven- work. Here we have the highest and fastest vibra - out much interest for us, I made an adjustment to tor, you must leaveg and tions so far known, X -Ray vibrations. The whole leave the ordinary sound range far behind the beaten path. = room seemed filled with the tremendous high pitch adjusted the sonophone for slightly above 30 mil- """""""""""""""""""""""""""` screaming sound that was so high that it became lion vibrations per second. Here electric vibrations I next directed the X -Rays upon a sheet reign. Suddenly sounds of jazz music came to our ears. Alice almost unbearable. Immediately we heard mixed in with the high looked at me questioningly. of lead. booming noises such as you hear "What you hear now," I explained, "is radio station KSD screaming sounds tremendous a battle. "Why the loud booming noises?" asked of St. Louis, broadcasting. The radio frequency vibrations are in naval I explain that as long as the X-rays were translated through the sonophone directly to your ears, with- Alice. hastened to with we heard the high pitched sounds, bit the out aerial or ground connection nor any radio apparatus what- not interfered we block the rays by means of lead there are collisions soever. These vibrations in ordinary everyday life are always minute between the rays and the atoms of the lead, causing explosions about us, only we do not hear them because our ears do not which were the noises we heard. respond to these high vibrations." Alice "Are there still higher vibrations? did not believe me, so she took off the GOLDEN AGE OF asked Alice. "Yes, I said, "if you go up head pieces. Supreme quiet reigned and THE to the 62nd octave you will have over she heard nothing. Convinced, she put SCIENCE 4T/z vibrations, but so far we on the ear pieces again and heard station quintillion is now symbolized by the golden have not been able to produce them. of Detroit, Mich. KOP cover of SCIENCE & INVEN- Just telephone rang, awaken- We then approached a high power elec- then the TION. LOOK FOR THE GOLD ing me from my pleasant dream. I in- tric line. A slight adjustment brought COVER every month! stinctively felt for the sonophones. They us in tune with the electric frequencies and secret. 11.1 ,,,,",,,1,,,,,1,,,,11,,,,,,, had vanished, with them their of this line. A high pitched sound was 411111,,,, ,,, ,,,,,,,,,,,1,,,,,,1,,,,1,,,,,,, 1195 Science aire! Invention for April, 1924 ffc,§ Peicpettu ód Mi o tü®h7-02

POR®IJS PORCELAIN OR OTHER WICK

POROUS CLAY OR SPONGES

AIRS PASSAGES

FILTER THIS SIDE PAPER \ y_ tHEAVIER fP HOLES, IN PIT TO NiSTEN,,

îpÉfiERATORS WHEN FILTER PAPER IS WET BALANCE. ROCKS ci DrIER

In the motor shown above advantage is taken of the loss in weight due to natural evapora- side absorbs enough water to causa it to over -balance the side now in the down position tion. Two receptacles are mounted on opposite ends of an arm and are filled with porous The two photographs on the right show a model of the system which actually works. bodies. These absorb water which rises in the stand pipe due The to capillary action, and pendulum rocks back and forth at a rate varying from forty seconds when one side becomes water laden, swings in the summer to one it downward, while the other side rises. It and a half minutes in the remains winter. Notice in the photos that a small piece of filter paper in this position until water evaporates from the heavier side and the lighter is attached to one of the beams of the balance. -C. Marshall. C®n51,mcgon ©f 5upew-AinhIlpe

When the lighter -than-air machine is finally adapted to actual freight and passenger stable and dependable yet devised. They were designed by Colonel Marcel de Passy, a service of large extent, it will probably take one of the three forms shown above since French engineer. The inverted U -type can lift 205 tens and can make a speed of 130 the world's most famous aeronautical engineers are agreed that thesr types are the most miles per hour. The X- and T -type:: provide extreme stability. -Ruth A. Krohn. Science and Invention for d Aril, 192.1 1197 nt Cllock5 China's Water Clocks Date Twenty Centuries Before Christ BY CHARLES BEECHER BUNNELL

e\utmmuü

This clock is a metallic KALENDER CL ham and was found in Pompeii. Its capacity is B L' 280 six hours from sunrise to w KALENDAR noon when facing east, and six hours from noon to sun- a set when facing west. The F- 51JN DIAL z top line is the horizon and each horizontal line following is a Roman hour, making the bottom one noon by A°79 our time. The vertical lines are the months. The first line at the left is January to June on the right, and then from July at the right to December on the left The time indicated in this drawing is the third hour of May 12th or nine o'clock in the morning by our time.

ló u- J5k O ]

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r shown In the position z clock rs :five o nutes beforrestesunrise. minutes emptying m The siphon is cylinder and lowering the the fig- the float, so that with the pointer will ure June register sunrise on 1st when the water wheel to the drum has geared its \ turned it 1 -365th of WATER diameter, which it accom- WHEEL \ plishes every morning at of sunrise, the beginning the Chinese day. This consisted of twenty-four unequal hours, twelve for daylight, and twelve for night time. The longest day in summer might have 75 minutes to the hour, while the shortest day in winter might register 45 minutes to the hour. The long summer days are balanced by the short hour summer nights. Hence the elliptic diagonal rings on the drum.

0 0 GALILEC'5 The water clock of A.D. 10 was similar CLOCK 11F in action to the Chinese clock, shown in the upper lefthand A b 1600 corner of this page, except that it had a twenty -four-hour dial chronometer The present-day divided into twelve escapement is found in Galileo's hours for daylight clock of A.D. 1600. There is and twelve for night. no spring present, however. le The variation in hour above device gravity takes the lengths were adjusted the place of the spring. by directly regulating CYLINDER the float valve at The clock shown above is of the year A.D. stated intervals. WIIIIIDgDIgIW 1 500-King Arthur's clock in the days of the round table. Notice that the graduations are accelerated because heat thinned the oil and also expanded the imprisoned air. This made a forced feed, which gave a brighter light the longer it burned. 1198 Science and Invention for April, 1924 Scientific Mating Science Shows How To Be Happy Though Married By H. GERNSBACK MEMBER, AMERICAN PHYSICAL SOCIETY

HOW much would the average man or woman give to know beforehand if his or her prospective married life is to be success or failure? At present, marriage is a lottery. It seems impossible to predict beforehand how your prospective mate will turn out in the future. Through certain fundamentals, which can easily be ascertained, one can be reasonably certain as to one's choice. We take extreme care in breeding horses, dogs and cats, but when we come to ourselves we are extremely careless and do not use .,ur heads nor the means that science puts in our hands for scientific breeding. There are certain basic tests which can be made today and which will give one a reasonable assurance of married happiness. Physical attraction ranks first in a successful marriage. In the lower left hand illustration, also on our front cover, we have shown how physical attraction can be checked up for both individuals. Both can didates for marriage are equippe'. with electrodes at the wrist fn operating the electrical sphygmn- graph which records the pulse beat ; around the chest of each is a chain which is secured to a piece of spring covered by a rubber hose. One end of the tube thus former is sealed, the other connects to a manometer and also to atambom supplied with a stylus. The stylus leaves a record on a moving paper tape showing the rate of respira- tion. Around the arm of each party is an inflatable band, the tube of which connects to a tan, hour leaving a record of muscular contractions. By means of these instruments, it is possible to check up the emo- tions of each when embracing or kissing. If the apparatus does not give a certain maximum of one of (Continued on page 1269) Science and Invention for April, 1924 1199

One of the most ingenious methods used by card sharps to trim their victims is the insertion of a small triangular steel into the end of a mirror Other pet methods for obtaining the salon result cigar, which reflects the cards is the insertion of a mirror in the end of a as dealt. match box or in the setting of a signet ring as shown in the illustrations at the right and left. Both methods allow the sharper to read the cards as dealt.

.. .,,zc./,°°,,/".,/°./"^':,%``"'.''l`e%`vd: ,:;`.,_dr.%'r^.T:. :': ...: A Gam.:0 er95 Empoeed. By MARK MELLEN, The Man Who Fooled P. T. Barnum Mark Mellen, born in one of the Southern States about 50 years ago, is a college graduate and law student. He learned enough law to keep out of its clutches and was never convicted of a crime. He has worked confidence games, operated gambling houses, made book at various race tracks, traveled with a circus while working the shell game and three -card -monte and traveled the ocean liners as a card sharp. Has always played the game fair to the extent that he always played square with his pals and confederates, but never hesitated to "take a sucker," claiming that no man can be fleeced except when he thinks he is about to take an unfair advantage of some other person. He does not hesitate to reveal the methods used in "trimming a boob" as he maintains, "Once a Boob, Always a Boob" and the more you show a real Book the easier it is to trim him. While many persons will profit by being warned. the real Boob will feel that he is "wise" and fall harder than ever.

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Others prefer using a larger mirror glued to the end of a cork which may be inserted in a pipe, as shown here. After the deal is completed, the sharper removes the cork and mirror from the pipe.

Still a third variation of the same principle is the use of a small mirror attached to the inside of a ring on the small finger. The PIPE RESL toz dealer holds the cards, as shown, and as he draws off each card to be dealt, an the image of its index is reflected from Quill toothpicks have fallen into great disuse in these latter mirror, allowing him to tell just what years, but in former times they obtained great popularity- in cards will fall with gamblers-because a mirror sheathing could easily be each player's hand. placed within them and used to reflect cards in the same manner as the other methods depicted on this page. If the dealer is using a quill, he might better be investigated.

Another variety of the ring mirror method of as dealt, is the con- illegitimately observing cards A seethed used by some few gamblers who are exceptionally of a ring with a split signet. The ring struction dexterous is illustrated here. The mirror in this case is a in much the same manner as the ordinary closes small steel square glued to the back of a small stack of poker held shut with a spring clip and when locket. It is chips. The chips of course must be exactly like the chips sharper obtains the deal, he merely opens the the that are used in the game. This method is a very efficient exposing a small mirror possibly a half inch ring one, but at the same time requires a great amount of skill on in the inside of the ring under the cover. By A>square the part of the operator so it is used in comparatively few the ring around on his finger, it is forced twisting cases. It is also made in the form of a mirror with a lip the inside of the hand shielding it from the view to which may be inserted in the stack of poker chips. of the ether players.

WONDERFUL NEW RING REFLECTOR, Our x.RAY RING ill the beet Reflector ever made and the only) one that will! do the work right. it Is one of the greatest little devices nted to read cards while your ar_ deaing. With this ring marled cardseds unnecessary. You env deal a man ards and tell him every and be holden a mot. marvelous performance to him. The Rejector is made in the ring; nothing to put on or take off In work. ing it; it an be worn at all times s in al pp it hl Tb, itaRsy Miaºm The slick gentleman to This convex mirror which is held in the of imitation.. the left is \, using a palm of the operator's hand requires aermine table reflector which is composed of a convex mirror hinged to more than ordinary practice to hold it in place a pushpin which may be Stuck into and deal the cards simultaneously. also the wood at the edge cif the table. It has the advantage-to the sharper When not in use it is folded -of being exceptionally safe, since it is out of almost sight. At his deal, of course, the impossible of detec- tionitheand is et elyat card sharper opens the mirror. As llconcealed in the pocket he deals the cards slowly he may at all times when not in see the reflection of each use. It has a one. bit of rubber at its back. t'

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CON EX MIRROR' -CONVEX MIRROR 1200 Science and Invention for dpril, 1924 ds thly Priz The Regular Departments Pay Prizes of Their Own. Authors on Contract Receive Their Own Rates; Making the Total Paid for Articles in Excess of $1500.00 Monthly.

FIRST PRIZE, $100 E. H. Swanson 1229 Thomas H. Duffy 1229 Graser Schornstheimer " " 1208-1209 Carlyle Weiss 1230 TWO PRIZES OF $50.00 EACH Harry R. Lubcke 1230 W. T. Markpwski 1230 Ernest Brennecke 1201 Robert Lee Bird 1230 L. B. Robbins 1211 Leroy Western, Reporter No. 15 1264 C. Fitch 12.72 TEN PRIZES OF $25.00 EACH Herbert C. Leonard 1272 C. Marshall 1196 K. Anderson 1274 Ruth A. Krohn 1196 Leo Chaviano 1277 Donald H. Menzel 1212 Harry Ackerson 1278 E. B. "Farmer" Dunn 1213 Belgrave F. Gostin 1278 W. W. Rodgers 1217 C. J. Fitch 1279 Walter B. Gibson 1223 Harry Ackerson 1282 Constantine Troy 1225 Charles Mallinckrodt 1282 L. B. Robbins 1226 A. Greental 1228 TEN PRIZES OF $5.00 EACH C. Doville Walker, Reporter No. 577 1234 Lewis M. Baldwin 1229 FIVE PRIZES OF $20.00 EACH S. Marchese 1229 Carolyn H. Gault 1230 Charles Nevers Holmes 1207 William Tredwell 1230 Author Article "Speed Reduction Gear" 1225 L. B. Robbins 1230 Clarence Ray 1227 Wm. H. Seitzinger, Reporter No. 3826 1230 Armstrong Perry 1236 James Williams 1271 Jack Kay 1240 F. R. Thresh 1274 John Rulison 1275 TEN PRIZES OF $15.00 EACH W. C. Chandler 1276 Marino and Bobkiewicz, "Universal Watch" 1219 Allen P. Child, "Tooth Paste Cabinet" 1219 TWENTY PRIZES OF $2.00 EACH J. W. Von Stein, Reporter 126, "Toaster" 121'1 ",Vm. H. Seitzinger, Reporter No. 3826 1230 Charles W. Geiger, '`Auto Safety Light" 1219 F. E. D. 1264 J. H. Jobson, "Burglar Gun" 1219 Roy Dooley 1265 E. C. Larsen, "Spark Plug" 1219 F. R. Donahue 1265 Charles T. Allen 1227 Glen F. Stillwell 1270 L. B. Robbins 1227 Stanley Robinett 1270 1)r. Albert Neuburger 1228 T. S. Stalker 1273 Gilbert Billin 1235 Bud Mulkeyn 1273 TWENTY PRIZES Monroe R 1275 OF $10.00L.EACH W. Orear 1276 Allen P. Child, "Screw Driver" 1219 A. Gilbert Billin 1277 J. W. Von Stein, "Potato Scraper" 1219 13. J. Oyer 1281 Author of Article "Spring Flashlight" 1219 Herbert T. White 1281 Thomas H. Duffy 1227 (Balance-Seven Prizes-No entries)

_:::::1:,l.::1...111,I1114,::.1:111.1111:,:111111111111I::1111,::::111111::14:I11:::4::::::::::.:::::::::: :::1: 1111111111.111111.1111111,11111111.11111111.11,q1,1111 ::111, Here Is How You Can Get in the Contest: $12,000 or More in Gold $12,000 or More in Gold 88 FVERY month SCIENCE AND INVEN- monthly prizes will be given as is IDEAS. These ideas ss be handsomely TION pays $1,000 or more ini gold in follows: paid for. We have pubii>hed a pamphlet prizes. - Every text article published will FIRST PRIZE $100.00 showing the rules of the contest which we receive a prize-(most of the departments shall be glad to send to anyone free on re- have awards of their own which they give 2 PRIZES of $50.00 each ceipt of a postal card with your name and every 10 1( month). Ideas are what the Editors 25.00 address thereon. The pamphlet gives full - want. The ideas must be told simply, so that 5 64 20.00 64 details of the rules and how to submit ar- 66 64 ticles. your mother or your sister can understand 10 15.00 The magazine itself shows you what - is wanted. Study them-in pictures or sketches or both. But f{ 46 it closely and submit your 20 10.00 ideas. the idea must be new and must in all cases " 64 10 5.00 closing have something to do with science or The date for all prize contribu- 20 46 66 2.00 tions is the 15th of the month preceding date 1. invention. 10 1.00 of issue, i.e., the 15th of May for the July 1 The Editors want pictures and sketches- issue, the 15th of June for the August is- - e must have them-but what they want most sue, etc. Il:llnnn:l::::mulm::m:: m::o::::i:mun:munn::::1:::nn:m:::t:::::::::::t::nn:nummunnu,:::::o:::minullr.

WILL YOU BE OUR REPORTER? Science and CORRESPONDENT REPORTERss IN connection with our $12,000 prize contest announced herewith, it goes without saying that you will have to do a little work in order to win a prize. The Editors do not wish to make it hard for you, quite file Invention DENTiFCAT1ON contrary. We want pictures and ideas and we cannot have too many of them. Herewith is reproduced our reporter's card. Up to now we have issued close to 8,000 of these. Note in NO. 99 rur awards how our reporters are winning prizes right along. We shall be glad to send the reporter's card THE BEARER OF TITIS CARD_ free to anyone who makes an application for it. By means of this card you will be able to secure entry into industrial plants, business houses, motion picture studios, steamships, docks, public buildings, etc. This IS AN AUTHORIZED CORR ONDENT REPORTER of reporter's card will prove an open sesame to you in many instances. Every card is numbered and only one is SCIENCE nd INVENTION MAGAZINE given to a correspondent. A postal card from you and a request for this reporter's card is all that is necessary THE PUBLISHERS OF SCIENCE AND INVENTION WILL to obtain one. It will be sent to you by return mail. With it we will send you a pamphlet giving rules APPRECIATE ANY COURTESY EXTENDED THEIR of the contest and how to proceed in order to get photographs, to send in sketches, and other information in order to obtain a valuable prize. Not only will this card help you to obtain material for this magazine. but it REPRESENTATIVE. EXPERIM TER PUBLISH will train you to become a news gatherer, and will be the means of helping you to earn a good deal of money iG C during your spare hours. (-s PRESIDENT Address Field Editor, SCIENCE AND INVENTION, 53 Park Place, New York

.n1I111,u1 m::::::nnnmuum::::nm:unnuw::::n:unm:nllllllll:l:uw::w:::nllnl:nwunu,nnwll,llllllll:lllllllllll::lolmn,:l:::l Science and invention for April, 1924 1201 Traveling On a Light Wave BY ERNEST BRENNECKE

THE START: PROF.VELOX GOING AT 100.000 MILES PER SECOND. BEGINNING -':. TO SHOW SHRINKAGE. AT 120.000 MILES PER SECOND.VELOX HAS SHRUNK - AND IS ONLY 5 ft TALL. ;je AT 156,000 MILES PER SECOND,VELOX IS ONLY Va HIS NORMAL HEIGHT- 3Ft TALL Twenty-five years ago a mile a minute seemed a terrific speed, but today, with the constant increase in the speed of airplanes, the question of the ultimate in speed arrives. A few years ago the Lorentz -Fitzgerald theory appeared stating that a body actually contracted in the direction of travel according to the speed at which it progressed; that is to say, a body flying through space will be shortened. Recently Prof. Henrik Antoon Lorentz of the University of Leyden worked out this law: The length of a body in motion is equal to the square root of its length at rest, minus the square of its velocity divided by the square of the velocity of light. What this law means is illustrated on this page. Suppose that a scientist, say Prof. Velo;, should devise a machine which would shoot him through space at speeds equal to that of light and greater. AT 171,000 MILES PER FASTER! AT 179.000 AT 210.000 M. AT 240.000M. SECOND,VELOX IS V3 AND SHORTER M. P. 5., VELOX P. 5., VELOX RE- P. S., VELOX HIS NORMAL HEIGHT STILL. FLATTENED APPEARS. BUT BACK- IS 2 Ft TALL, 2 Ft TALL. BUT JUST TO A THIN DISK. WARDS.GOING FEET- JUST AS STOUT AS BROAD AND STOUT FIRST.TURNED INSIDE. AS EVER AND AS EVER. OUT.AND I FOOT GOING BACK - 4" r TALL. WARD STILL.

AT SPEED186,000 IGHT, 1 I MILES PER AT 174.000 M.P.S., SECOND,VELOX DIS- VELOX LESS THAN !4 APPEARS! NORMAL HEIGHT. fr*

At the start of Prof. Velox s journey, when he traveled at 100,000 miles per second, his body would begin to show shrinkage. If the Professor were six feet tall when he traveled at 120,000 miles per second, his height would decrease one foot. As his flight continued he would become shorter and shorter, until at a speed of 179,000 miles per second an observer on earth would see the Professor only as a thin disk. According to the law set out above, when the Professor attained the speed of light, he would disappear entirely, but then as he increased his speed, he would appear again, going feet first-evidently he would have turned inside out ! les AT 300.000 MILES PER AT 360.000 MILES PER SECOND, SECOND, VELOX IS 4 Ft. VELOX IS AGAIN NATURAL SIZE. TALL. BUT TURNED OR6F+ TALL- HE LANDS - BUT BACKWARDS. FINDS HIMSELF TURNED INSIDE OUT :

RECEIVER FOR VELOX2

As he continued to increase speed his length would also increase until when the Professor carne to a speed of 300,000 miles per second, he would again be four feet tall, and at 360,000 miles per second Prof. Velox would again be his natural height. But suppose the Professor fell into some sort of receiver which would absorb the shock of his speed. He would present a most amazing spectacle. As his audience extended a hand of congratulation, they would be surprised to find the Professor's thumbs on the wrong side; they would find his feet turning toward the outside instead of the inside, as regularly, and altogether reversed. His heart would be beating in the right side of his chest! 1202 Science and Invention for April, 1924 The Man On the Meteor PART FOUR OF A SERIES By RAY CVMMINGS

SYNOPSIS OF "MAN ON THE METEOR" WITH no memory of past events, a young man suddenly comes to his senses on a meteor which is part of one of the rings of Saturn. Be. ing hungry and thirsty, he looks around for nourishment and finds the mouth of a cave. As he looks towards the cave a girl comes into view. The young man, who calls himself Nemo, enters the cave and alter traversing some little distance finds it to be illuminated by the phos- phorescence of the rocks forming its walls. The problem of finding sufficient food became paramount in the life of Nona and Nemo. One day upon returning to the cave Nona shows Nemo several mollusks which make good food. She then takes him to the place where she found them to gather more. They Wade into the stream and follow it into its cavern. Nemo sees that Nona's head is completely engulfed. Soon his head goes under water and he feels the liquid rush into his lungs. However, by violent effort he is able to breathe. He finds that the The thing went past us- water, being so highly aerated, readily supplies quietly, without seeming to his blood with the necessary oxygen to sustain notice us. it was a ribbon-like life. They come to a bed of shell -fish, collect thing thirty feet long, two feet enough for their needs and go back to their high, and no more than a few inches home in the cave. They start a fire, cook their thick. A pallid white ribbon of supper and retire. puffy slime, frayed and tattered In the middle of the night they awake to find at its edges, it undulated their entire cavern in flames. The rock, being of gruesomely from end to end. a combustible nature, has become ignited from the cooking fire. They dash toward the mouth of the cave and out to the surface of the meteor. Thus robbed of their home they "swim" through the air to the opposite side of the planet. Here they make their home beside a large stream at a point where it enters a low hill. Soon smoke denly seized with an idea and taking Nona with party of ten people, four men and six women, and fumes from the conflagration drift over to him he plunges into the water and follows the bed who are somewhat human in form, but have four their side of the small meteor. Nemo is sud - or the stream into the mountain. Soon they arms like the tentacles of an octopus. Nemo and find food and devour it, still under water. Nona are captured and tied by them. A large At this point they see coming toward them a vehicle is seen coming along the bed of the stream and the Marinoids, as Nemo calls his capturers, prostrate themselves. Nemo does not follow suit and the occupant of the vehicle throws On the platform also, between Og and the white old men, a spear at him. He is struck and falls senseless. my Nona was sitting with her trms bound at her sides! My When Nemo cornea to his senses, he and Nona, beautiful as always, pint skin, blue eyes and golden Nona are taken by the Marinoids to the city hair-so vivid am d that pallid, ghastly throng! And she was called Raz. This city is under water and, unlike unharmed-with Spirit unbroker-1 could see that by the the cities of our earth, is built of underwater Sash of her eyes, her scornful, unwavering gaze as she leveled vegetation. it at the puffy white faces staring up at her. After Nemo and Nona have lived with the Marinoids for some 'few months, Nemo becomes practically indispensable to the ruler or King of the city and is consulted by him on various occasions. The couple lived in the same home with one of the Marinoids, but after their child was born, whom they named Boy, they were given a home of their own. Soon after this a man named Og insulted Nemo and challenged him to a fight. The fight took place in front of the palace of the ruler and Nemo was defeated because Og had a peculiar property, which was characteristic of the Marinoids, enabling him to send a charge of animal electricity into the body of Nemo, thereby rendering him unconscious. After the fight, Nemo is brought back to consciousness by Nona. He finds, at a later date, that the electricity used was similar to that found in the body of the electric eel, common on the earth. After recovering fully, Nemo starts to look for his recent adversary, but is unable to find him, and he soon learns that Og has left the city.

IGO back again ill my memories to that year in the underwater Marinoid city of Rax-the year of quiet and peace for Nona and me which followed the birth of our son. Boy, we called him; everyone called him that, for he was the only child of his kind in our world. It was a wonderful, happy time for us both. In all the Universe there was never another like our Boy. So thought Nona and I. Pink and white, with his laughing blue eyes, and soft blond hair on his little head, he would lie cradled in the big white shell that stood in the center of our living room. The tiny bits of vegetation which often floated in the water past his face were his toys to snatch at and demolish; and Nona, who fed him, crooned to him, and when he was no more than a month or two old guided his baby flounderings into swimming strokes, was the center of everything around which his infant world revolved. For myself, almost an outsider with these two, it was enough to watch them playing Science and Invention for April, 1924 1203 together, to see the light of motherhood in on a similar plan. It's like a puzzle-a jig- The boundaries of the Marinoid domain my Nona's eyes, and the glory of it on her saw puzzle whose picture remains undefined presented themselves as almost perpendicular face. until you fit the last segment into place. cliffs-dark, jagged rock, with slabs and The time-unmarked by daylight or dark- So it was with these ominous events that banks of black clay, mounds of coral, red, ness down here in the water-glided by; now occurred one by one in Rax. (And the black and white, or a tangle of slimy vegeta- and for us the passing days meant only that absent Og, I may say, was at the bottom of tion. Openings which were caves-a cliff - Boy was growing larger, his limbs were them.) Each in itself seemed relatively un- f ace honeycombed with them. And the ceil- lengthening, his neck would now support his important. Yet all were part of a plan of ing was of similar character. head, he could swim and soon he would destruction that was menacing us like an One of the boundaries-the one nearly op- begin to talk unseen sword hung suspended. We awoke to posite to where Nona and I had entered this world-was somewhat different. Here the cliff -face rose to over three thousand feet. But here also, the ceiling was even higher, so that between them there was left an opening a hundred feet or more in height, and a mile, at least, in horizontal width. It was a fearsome opening. Its floor seemed to extend backward and downward. The water in there was black; a thick slimy ooze was under it. And there seemed to be in it the suggestion of a noisome stench that lay beyond. This was the entrance to another region, of unknown extent-the Water of Wild Things as the Marinoids called it. What might lie in there, none could say. A few had penetrated into it a short distance, and returned with lurid tales which none believed. And others had gone and never come back. Caan and f whirled downward, shouting. Through the But that there were half -savage- humans window of a house, we saw the stiffened body of a living there, everyone believed. O¢ was woman come floating. There was light enough for us to see her white face and arms --a woman unconscious, bred of them, some said; and now that he shocked into insensibility as we later learned, by a had voluntarily gone there to live, as rumor bait of animal electricity from her abductor. had it, so much seemed a certainty. a realization of the danger, finally. You shall Strange animals occasionally came from Thus can happiness exclude one from the hear how it was I, who-when the thing at the Water of Wild Things. A sea -monster world around. Yet it must not be inferred last struck home as a personal tragedy to me had come once. But that was in the dim that we lived at home in complete seclusion. -played a leading part in the stirring scenes past, remembered only by legend. The mon- There were happy times with our friend that followed. ster had all but overcome the cloud of Caan and his family-in his home when Boy May I ask you first to bear with me a Marinoids who had desperately set upon it. would lie there asleep and we others would moment more, while I give you a very brief Such were the conditions under which we, play at a game of floating shells. summary of conditions in our Marinoid at Rax, were living. world? I know you will chafe. A thou- And there were other times when I went And now I am ready to tell you of that He seemed to like sand supposedly pressing duties of your own hunting with the Prince. series of incidents which awakened us to our his friendship I must confess, was super -civilized life are forcing themselves me-and danger. They did not at first concern me to me a great joy and pride. Like many upon you even at this moment of relaxation. another Prince of your own Earth, Prince Set them aside, I beg you. They are not personally, and so I paid them little heed. Atar was a sportsman. Occasionally, head- nearly so important as you think. If you That is a commentary upon your own life, ing a little party of his friends, he and I were to die tonight, leaving all of them un- is it not? Soon the thing struck home to me would hunt together, swimming off toward done-your world would go on as placidly with its tragedy. Ah, then how different it as before. the Water of Wild Things, where, over the seemed 1 We can bear the grief of our cliffs which bordered the Marinoid domain, A moment then-and you shall have action friend so much more philosophically than our strange fearsome creatures would sometimes and movement to your heart's content. ownl trespass. (Continued on. page 1285) CITY'S WORK II My means of livelihood? Oh yes, I was a worker like the rest. There was no place The region of the Marinoids was a stretch in Rax for a drone; and Nona and I were of water bounded by great rocky cliffs on by no means guests of the city-no longer all sides. It was subterranean water-by than the first month or two. When they which I mean that ascending in it one came gave us our home I was assigned to work at last to a rocky ceiling. We were, at Rax, with Caan. After each Time of Sleep, we near the center of this subterranean sea. swam out with our baskets into the open What was its extent, I cannot say. All spaces beyond the forest which surrounded measurements, all standards of comparison, the city. We would gather up the shell - were lost to me. In depth-at Rax-it might food that lay on the sea -bottom. It was con- have been two thousand feet or more from tinually sifting down from above, and what the sea -floor to the ceiling above, which is we collected was later gathered and drivent to say some two or three times the depth in to Rax, to the government store -houses. of the city itself. Coon's wife worked with us-for women, How many entrances there were from the even though married, were obliged to work outside world, I do not know. Through one for the public good a portion of the time. of them Nona and I had come when Caan After Boy was born Nona, too, often joined and his party first encountered us. To the us-though this was not obligatory, for the Marinoids, who were not explorers, the idea care of infant children discharged a woman of a surface to water was inexplicable. of the debt of working otherwise. They could not conceive of such a thing; There is so much that my memory holds they could not understand it when I tried to tell you of this strange Marinoid civiliza- .to explain it to them. tion! But you, with your life to live at high There were several Marinoid cities be- speed, would weary of me if I were not sides Rax, but none nearly so large. And careful. You want everything at a glance- there was-shall I say a rural?-population. and you shall have it. In the great forests, Marinoid dwellings Let me say then that during this peaceful were occasionally to be found-isolated huts year there were occurring in Rax a series of sea -weed, clinging -like bird -nests to the of .mysterious incidents of an exceedingly wavering branches of the trees. And in the sinister character-incidents which shortly open water other scattered families of the There was a balloon of white Jelly. It floated past us were to lead us into the most stirring and more adventurous turn, lived in huge shells quite close. It seemed harm'ess and Atar swam beside it. of Marinoid history. But we from which they had excavated the living Then suddenly the thing expanded, lost all its form and critical period like a cloud of white mist, enveloped him. did not know this at the time. Life-where- tissue-or lived in holes hollowed out of the ever in the Universe_ it may be found-runs banks of black ooze. 1204 Science and Invention for ,4pril, 1924 Dr. Iiachensaw's Secrets By CLEMENT FEZANDIÉ No. 28 Formerly it was a common practire to keep --The Secret pet dogs small by administering suitable of Size doses of alcohol. This seemed to check the proper assimilation of food and therefore "Wh- wh- what?" the growth of tissue. Certain scientists have "Metabolism. To speak more simply, they claimed that the pineal gland consider the question in the brain, one of nutrition or determined the size of the animal, but this food. Anabolism is the building up of tis- theory may be disregarded. Very little is sue, and catabolism is its destruction. If an known about the pineal animal gland, so that it or plant gets a great deal of food, makes a very convenient nucleus to hang any and can assimilate it, it grows to giant size. theory on; and all sorts of powers have Dn the other hand, if it is starved, it re- been attributed to it." mains small, it is dwarfed." Here Doctor Hackensaw paused for a "Nonsense!" cried Silas Rockett. "Do moment, and then continued: "I had not you mean tc tell me that if I fed a baby carried on my experiments long before I rabbit and a baby elephant the same amount became convinced that the question of size of grass, the rabbit would grow to the size was one of nutrition; and yet not quite in of the elephant?" the'way ordinarily imagined. An experiment I made with dogs led me to view the matter A QUESTION OF ASSIMILATION in the proper light. You have probably seen the pet dogs the ladies are so fond of,-the "Yes, if il could properly assimilate the Toy Pomeranians, small enough to be food. Otherwise you would merely kill it. cuddled in one hand. Well, it struck me The theory of metabolism is the true one, that, here among dogs, where we have giants but I did not find it of much assistance. like Great Danes and St. Bernards and True, we see examples of it every day. The dwarfs like the Pomeranian, there was a weeds around a manure -heap, for instance, fruitful field for research -work. I accord- grow taller and ranker than normal ;-in ingly took a fertilized ovum of a Toy fact I have seen such plants grow to three Pomeranian, and one of a Collie, and intro- or four times the usual size. A man three duced both of these into the womb of an or four times the normal size would be a ordinary -sized dog. When she gave birth giant eighteen to twenty-four feet high. In to the puppies, there were, as I had antici- the case mentioned, the amount of food pated, a Pomeranian and a Collie. The seems of itself to be sufficient to produce the former remained small-the latter grew to excess of growth. On the other hand, normal size. Both had received the same there are also well -authenticated cases with nourishment in the mother-evidently the regard to dwarfed plants. The Japanese, difference extended further back-it extended for instance, achieve considerable success in as far back as the fertilized cgg. Doctor Hackensaw had started a Brabdingnagian farm. producing dwarfed trees. They produce "Here, on Trees but a few years old were there, yet they towered the very verge of success, I higher than the gigantic California redwood trees. Giant dwarf apple -trees about one foot high, per- was non-plussed, and I got off on the wrong animals and plants of many varieties were present fectly formed in every respect, and bearing track. 'If,' thought I, 'I could change every real apples! These miniature trees are pro- one of an animal's cells to double or triple (Author's Note.-What causes size? Why, duced, I am told, by giving the young plant their normal size-the animal itself should in a normal family, will a dwarf occasionally barely food and moisture enough to keep it be two or three times its regular size. And be born; while, in another normal family, a alive. It thus grows for years and years, if, on the other hand, I could reduce the size giaist will suddenly appear? What causes and yet remains diminutive in size." of each cell, the animal itself would be these exceptions? Every abnormal growth, "How about alcohol? I thought animals dwarfed.' The theory was very plausible, every monstrosity, has its reason for being, were stunted by giving them alcohol?" but it led me nowhere. All my experiments and the function of science is to discover "Yes, the case is somewhat similar. in this direction failed. these causes. Once known, we may prevent these growths, or, if we so desire, we may produce giants and dwarfs at will.) dd ERE I am again, doctor," cried Silas Rockett gaily entering the laboratory. "My newspaper, 'The New York Daily Growl,' wants some particulars in regard to your giant rabbits." "What particulars do you want?" "In the first place, is it true that you have live rabbits the size of an ox?" "Yes, it's perfectly true." "Next, my editor wants to know how you produced these creatures." "Ah, Silas; it was no easy job, simple as the matter really is. But I got started on the wrong track. For years I have been seeking to discover why it is that an occasional giant or dwarf is born, but it was only after long research that I discovered the 'Secret of Size.' Still I finally solved the problems, and I have some specimens of my work at my country -place in New jersey that I am sure will interest you." "The 'Secret of Size'?" echoed Silas. "What is the Secret?" Doctor Hackensaw smiled. "That's a thing that has puzzled many a scientist, and all kinds of theories have been advanced to account for abnormally large or small growths. Still, in general, scientific men believe the cause of the occasional production of giants and dwarfs to lie in metabolism. "Thote are my pets!" said he. "Those They art giant bacteria and bacilli. 1 have here the disease -germs of cholera. confider it the effect of anabolism and Malaria, yellow -fever and of illnesses. many other By growing them to this gigantic size, 1 can study them much catabolism." better than I could through a microscope, hod learn their life history and the effects of remedial agencies." Science and Invention for April, 1924 1205

"At this juncture I chanced to read the that would ordinarily produce a male, with its cubical dimensions and weight are 1728 result of some of the experiments made by a cell that would produce a female, and thus times the normal ones. For my insects I Dr. Driesch on fish's eggs, and by Jacques combine the two different cells into a single increased this proportion considerably, as Loeb on the eggs of the sea -urchin. Dr. egg. Again, this method enables me to make I wished large specimens for the purpose of Driesch cut a fish's egg in two, and suc- marvelous crosses and produce hybrids im- study. A giant fly, a giant mosquito, and eeded in growing a complete fish from each possible in rature. I can join the egg -cell a giant spider afforded me much valuable :half-egg:-one egg thus producing two fish! of an elephant with that of a mouse, and information. Unfortunately the spider got away one day and found its way into an old maid's meeting. They called themselves the `Click -Clack' Society, on account of the busyness of their knitting needles; but would be nits dubbed them the 'Clack -Clack' Society, or even the 'Cluck -Cluck' Society, claiming their tongues wagged faster than their needles. "Well, my giant spider got in among those elderly spinsters and broke up the meeting. Reliable eye -witnesses declare that the display of hosiery and lingerie on that occasion was more wonderful than any ever before seen in the town. "As for my earth -worms ;-well my chauf- feur, Pat, came across a bunch of these wriggly giants one day, and declared he had never seen anything, like it-at least not since prohibition came into effect." GIANT PLANTS "How about your giant plants?" asked Silas. "The plants gave me considerable trouble. The seeds had the bad habit of getting scattered around, and as they grew into giant plants, this naturally gave the farmer "That four-year -old baby giant you see over there, is looking at his twin brother- a four-year-o!d dwarf held in the considerable trouble. My most valuable re- palm of its nurse's hand. Yet both were grown from the same egg. Quite a contrast between the two, isn't there sults were obtained with wheat. In this in- -the first child fifteen feet high and his twin brother about five inches in height!" said Dr. Hackensaw. stance I exceeded my twelve to one limit, for my grains of wheat are about the size of musk -melons. Jacques Loeb carried the experiment a step get a freak animal any size I desire. I can A single grain will furnish further. He took a sea -urchin's egg, raised combine a dozen different animals together a good sized family bread for several days. My giant fruits, too, are remarkably handy Lt until it had reached the sixteen -cell stage, in this way-in fact I have hybrids of the and then cut it into sixteen pieces. He raised whale, the rhinoceros, the dog, the cat, the for the kitchen. My huckleberries and cur- each of these cells separately, and thus suc- ostrich and the salmon, all joined together rants are the size of small melons, which makes ceeded in raising sixteen sea -urchins from a into a single animal. It makes the most it easy to extract the pits. My single egg that would normally have pro- wonderful combination. cherries are as large as pumpkins :-it duced only one animal! But (and here was "But to return to the subject in hand, I doesn't take long to pick them, but you've the ray that threw light on my problem), the would say that I have completely mastered got to be careful; as one of them, falling sea -urchins, when mature, were smaller than the question of size. I am now able to pro- on your head, would make you see more the normal size. They had not had enough duce chickens as large as ostriches, pigs as stars than are shown by an ordinary tele- capital to start with, and had remained large as a rhinoceros, and cows as large as scope. All in all, my fruits are a wonderful dwarfs. Size is evidently a question of nu- some of the extinct antidiluvian monsters. success, and you must taste some of them. trition, but the problem has to be referred There is no danger now of our supply ever I meant to start canning them, but have too back to the egg stage. running short. A ham will last a family many demands for the natural fruit. for a month, a hen's egg will feed a dinner - "You mustn't believe, however, that I was DWARFS ALSO party, while one cow will give enough milk satisfied with merely increasing the size of our ordinary articles of food. I wanted to has succeeded in doing the to supply a dairy." "Science also go further. I wanted to experiment with very reverse. Experimenters have taken "How do you milk your giant cows?" asked the reporter. those animals and plants which are now too :wo separate eggs, joined them together into small to be of any use to man, yet which one, and hatched a single individual out of SOME PROBLEMS might prove valuable if increased in size. this double egg. And this individual, as But why I have expected, am chattering away here? Just might been was larger than Doctor Hackensaw smiled reminiscently. (Continued on Page 1283) the normal. Ample capital at the start had "That, Silas, was no easy problem," said he. given it an advantage in the race for life. "My hired help were all afraid to go near My problem was solved!" the huge creatures that could crush them to "You mean to say that you can produce a pulp by inadvertently stepping upon them, dwarf or giant animals and plants at will?" and whose twenty-f(.ur foot long tail could "Precisely. To produce a miniature St. swish them over like bine -pins. Just think Bernard dog for instance, I take a fertilized of having to milk a brontosaurus twice a egg -cell from an ordinary female dog of day! Ordinary methods of milking would, the species. I grow this ovum in a test tube of course, be impossible. I have to use a is a suitable culture -fluid, and keep separat- milking machine somewhat like that used in ing the new cells as they form. In this large dairies. I had even to devise special manner I can, from a single egg -cell, pro- stalls for the beasts, so my men could attend duce a hundred or more dwarf dogs. If I to them without danger from either horns, want a giant dog, I reverse the process. I hoofs or taiL" take a number of fertilized egg -cells, join "What about your other giant produc- them all into one single large cell, and grow tions?" this to maturity." "My gigantic products are especially use- Is it as simple as all that?" ful for furnishing a plentiful supply of tid- "Simple! It is exceedingly complex, and bits. For instance, my quail are so large many curious problems are involved! For that a single individual will supply quail -on - example, I can produce a dozen giant dogs toast sufficient for a banquet. My frog -legs from a single egg. I grow this egg to the weigh several pounds apiece. The liver from sixteen -cell stage, then unite these sixteen a single goose will make 1728 times as much cells into one large cell and grow this to the pâté -de -foie gras as that of an ordinary sixteen cell stage and so continue indefinitely. goose. And so on." This I find most useful when breeding thor- "1728!" echoed Silas. "Isn't that pretty oughbred stock. From a single egg from the close figuring?" most perfect animals I can produce a hun- "Yes; but you see, I find it convenient, as dred young the same size as the parents, or a rule, to make my products on the scale The day follow'ng the "New York Dai'y Growl" appeared with this head ine: "Escape larger or if I can inch. glaring of Doctor Hxkensaw's smaller desired. also proof a foot to the Consequently an Gigantic Anima:s. Cow. the Sin of a Brontosaurus Run- duce freak animals. I can join an egg -cell animal is twelve times the usual length, and ning Wild in Harlem!' 1206 Science and Invention for April, 7924 World's Greatest Bridge Monster Span Will Incorporate Cantilever and Suspension

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WHAT will be the biggest bridge in both length of span and height of suspension in the world, if it is constructed, will be the contemplated Golden Gate bridge between San Francisco, Cal., and the opposite northern peninsula. The total length of the central span of the bridge from shore to shore will be 6700 feet. At 1345 feet from the shore on each side the water is more than 300 feet deep. This makes the total length of the central span of the bridge 4000 feet. In order to effectively support a carrying structure across this great space it will be necessary to use both the cantilever method and the suspension method. From the towers which are 777 feet above the water level, the cantilever construction will extend back to the approach and over the water. The cantilever arms will extend 660 feet out into the main span and from the end of these arms suspension cables will be used. The towers upon which the bridge will be suspended, will have a total height of more than 950 feet, making them almost as tall as the Eiffel Tower. The design shown here was worked out by J. B. Strauss, an eminent bridge engineer, who is president of a Chicago bridge company. The reason for the combination of the two systems of suspension, according to Mr. Strauss is that the cantilever type OBSERVATION TOWER demands too heavy construction for such a long span, incurring an SHOWING ELEVATOR extraordinarily heavy frame in order to support the weight of the bridge itself, aside from the demands made by the weight which the bridge is to -- carry. On the other hand, suspension cannot be used alone since the e3 Z-- length would give the bridge a great lack of rigidity-which rigidity is essential in constructing spans the length of the one contemplated. span would be 750 feet longer than the proposed Hudson River The two main cables which would be necessary to support the bridge. One of the chief problems confronting Mr. Strauss in the bridge would be one mile in total length and would weigh approxi- design of this bridge was the fact of the existence of very high mately 5,250 tons. Their cost would closely approximate two and winds at the point where the bridge is to be constructed. The added a half million dollars. The width of the roadway space would be strain placed on the structure by this element had necessarily to be eighty feet; there would be one single deck only. The suspension considered at every point. Science and Invention for April, 1924 1207 f®r Golden Gate Structure to Cost $17,000,000

OF PROPOSED WOOLWORTH TOWER BUILDING GOLDEN BRIDGEI GATE N.Y. CITY 777 FEET ABOVE HEIGHT WATER LEVEL 792 FEET CROSS e SECTION OF MAIN TOWER

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ALL OF THE BfG BRIDGES 1N NEW YORK CITY INCORPORATED INTO ONE HUGH BRIDGE BROOKLYN, WILLIAMSBURG.MANHAT TAN .QUEENS BORO',WASHINGTON.HELL GATE ,3ePAVE WILLIS AVEMADISON AVE., 1415'±' ST. AND OTHERS WOULD REACH FROM 13R00 K LIN BRIDGE MANHATTAN TRANSFER 3TATION,N.J. TO EAST NEW YORK, RIPER SPAN 1,595 FEET DISTANCE 12 MILES TOTAL LENGTH 6,01(c FEET

EAST NEW YORK. BROOKLYN

tede <.-v i 12 MILES "11+1f

In the top illustration above is shown a comparison between the Charles Nevers Holmes' idea of giant New York bridges. The height of the Woolworth Beilding, the highest structure in New large 12 -mile bridge shown incorporates all the New York bridges York, and the height of the towers which will support the proposed built in the last 54 years. Were this 12 -mile bridge stretched across San Francisco bridge. Elevators will be installed in the towers from New Jersey to Long Island, it would pass clear over Manhat- which will carry observers to galleries which will be built at their tan Island, having one pier built on the Jersey shore; the other tops. This will give a wonderful view of all the San Francisco would fall toward the center of Brooklyn, while the approaches harbor. A cross-section of the tower showing the method of con- would carry the total length clear across the width of Brooklyn and struction is given in the insert at the top drawing. well over towards the center of Jersey City. In the inset is Speaking of bridges, we see graphically illustrated below Mr. shown the comparative size of the famous Brooklyn Bridge. 1208 Science and Invention for April, 1921 reparations Made For Huge Tanker Rebuilt as Mooring Vessel BY GRASER SCHORNSTHEIMER

The contemplated trip of the world's largest airship the Shenan- doah to the North Pole, entails much more preparation than the mere plotting of a course and filling the tanks with gasoline. One of the first necessities which had to be met by naval engineers in preparing for this flight was the building of some sort of a movable mooring base. They hit upon the plan of building a mooring mast aboard a vessel. The mast will be very similar to the one now used by the big ship at its hase at Lakehurst, N. J. This mast is shown in the illustration at the left. A duplicate of this mast will also be erected at some point probably up near the Arctic Circle in Alaska, which will serve as a starting base for the last leg of the Trans -polar flight. A temporary base with supplies and repair -shop will be built at the same place.

This relief map shows a number of the various proposed routes which may be settled upon by the Naval engineers for the flight. One of the chief reasons for the Trans- polar trip is to make discoveries through a large unexplored area which lies between Cape Barrow, Alaska and the Pole. A study of weather conditions, fuel and supply possibilities, will probably be the final factors in the selection of the route finally taken. The flight will end at Spitzbergen where the Patoka, the mooring ship pictured at the bottom of the opposite page, will be stationed to await the di- rigible's arrival. The unexplored area on the map has been the subject of a great amount of conjec- ture. It has been said that a warm continent heated probably from a geyser or a volcanic formation exists in this area.

- ". ,._ - - _

Here is shown the *United States ship Ramapo as she now appears. Corporation. She will be rebuilt as a mooring vessel for the She was originally built as an oil tanker for the Emergency Fleet Shenandoah. She has a displacement of approximately 17,000 tons. Science and Invention for April, 1924 1209 Shenancloah9s . (Aar Flight The Discovery of Warm Polar Continent a Probability NAVAL ENGINEER

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Above we have a drawing showing how the Patoka w:11 look fitted airship. She will also be equipped with a repair shop from which out for her ròle of mooring vessel for the Shenandoah. The vessel any necessary repairs incurred during the flight, may be remedied will have a small mooring mast, will have ample storage capacity before she starts on her return voyage. There will also be a sort and carry an emergency supply of helium gas for the use of the of airplane hangar aboard the vessel where airplanes will be carried.

2"OUTLET AT TOP OF MAST FOR - DISCHARGING HELIUM TO AIRSHIP

OFFICERS QUARTERS, CHART ROOM AND WHEEL HOUSE BRIDGE a11 I2`HELIUM MAIN

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What the cross-section of the Patoka, rebuilt, will look like when installation of piping from the tanks up the mooring mast and to she leaves for her trip to Spitzbergen; note that she wüll run prac- hose so that the giant airship may have her supply of gas replenished tically empty. One of the outstanding points of construction in this with the least possible expenditure of time and trouble. The details vessel is the installation of the helium storage tanks, aft, and the of construction of the mooring mast are plainly shown. '1210 Science and Invention for April, 1924 Vision Via 5oun ayes Audio -Frequencies Act as Carrier Waves

Perforated rids Box containing reyo/vine at various selenium ce// speeds whichproduce converting light audio frequencies waves into sound/ waves Lens

Coin/es to ordinar wireless transmit ter

Side of box removí

In the transmitter illustrated above for this new apparatus for the transmission of pictures by radio, devised by Dr. Fournier d'Albe, each of the perforated grids revolves at a different speed, setting up an audio -frequency note at the photo-electric cell which is shown at the extreme right of the transmitter. The strength of these audio notes depends upon the amount of light reflected from the sub- TRAWS/Y1/TT//yG ject. The image to be transmitted passes Motor Cab/es STAT/ON through the first lens, the revolving grids, the large lens and then on to the photo -electric cell. whose current goes to the transmitter.

The sound waves are sent out and received in the ordinary way

Enlarged view of dots The pictures are reproduced through much the same princip'e as that used in half -tone printing; it is the showing outline of on size of the dots which form the image that produces How an image is object in various shades the shading. In the insert at the right is shown a reproduced in the greatly enlarged reproduction such as would be produced by such an apparatus as pictured on this page. form ofa series Below is the receiver for this television apparatus. of dots The output current of a receiving set passes to the L_ loud speaker shown. The sounds impinge on the small tubes, each of which is equipped at its end with a mirror which is attached to a stiff vane Reflecting ends Resonators and held in the mouth of the tube. When the of sounds to which the tubes are resonant strike Box lined with each responding to its own note them the mirror vibrates according to the and reproducing in the form strength of the sound. The strong light in the ound resisting it bottom of the receiver casts its rays against these material of a shade of color. mirrors from which the light is reflected to the ground glass screen where the image at the transmitter is created again.

Image of speak Sound signals er reproduced received on screen +-Wireless Receive,

Loud speaker Beam oflight transmitting directed onto into Resonators Resonators Lamp t Re /ecfo R-ECE/1//NG J Science and Invention for April, 1924 1211 Ancient Methods of Raising Water The Forerunners of Our Modern Pumps By L. B. ROBBINS

- STOP PIVOT. LOOSE BUCKET DISCHARGE

DISCHARGE

TREADMILL '' itg.._.0e, ROPE PERSIAN WHEEL . The old Persian Wheel is e, more or less well known. It was an outgrowth of older PLANKED wheels which used stationary CYLINDER ,,r, buckets. The Persian Wheel Y by using swinging buckets and A BANTU. r a tipping peg, gained greatly SCREW in efficiency over the older The Jantu was one of the most ingenious and cunning wheels. This formed the nu- of all TO \-% ancient methods of raising water above its own level. A cleus for many modern water double series of gutters arranged in zig -zag fashion and swung DISCHARGE %e, wheels. from a pivot, as shown above, was pulled backwards and forwards by two operators. The gutters filled on the down e stroke and emptied on the upward one. "wer-,r ,lY ROMAN SCREW RESERVOíR The Romans who were blessed with a large amount of man -power developed the screw which is illustrated above. It is nothing more than a double screw built around a wooden axle and placed in a water -tight casement with a tread -wheel on the upper end. The FlXED PO water is raised by the screw action.

LARGE VALV E 264>BUCKET PIVOT SHOCK a> ABSORBER sTr DISCHARGE BUCKET GAINING- AND LOSING- BUCKET. OF FSET More or less on the -same principle are the gaining end losing buckets. The water falling into the large bucket on the short end of the lever raises the smaller bucket on the long end of the lever te the desired PADDLE WHEEL height. This is an exceptionally inefficient method of raising water but is easily and cheaply constructed. POSSIBLE VALVE PLUG-

The father of most all our The double Swape involved a which principle has fallen more present day hand pumps is or less into disuse at the present time as a method of utiliz- BOX shown above. It is a German ing waterpower for raising the water itself, on account of its invention and the first of all great inefficiency and the trouble of installation. As the water the pumps to use atmospheric wheel revolves as shown above, it raises the buckets alternately. SUCTION pressure for raising water. A BELLOWS PUMP large bellows was supported over the stream and connected to a vertical intake, raising the handle created a vacuum in the pipe, allowing the atmospheric pressure to force the water up.

The siphon originated centuries ago. ANCIENT S/PHON Here is an illustration al one of its earliest forms used to raise water over a slight bill and releasing it at a lower level. BRACING- BOARDS WATER TIGHT REVOLVING GUTTER DI SCHARGES JOINT THROUGH HOLLOW AX LE WATER`

W/RTZ ROTARY PUMP ANCIENT A somewhat later pump using mechanical parts in the form of a large TYMPANUM coiled tube suspended on bearings and rotated at such a height above the water te be raised that only the outside end of the pipe passes through The ancient Tympanum was a slight improvement the water, is shown above. The constant weight of the water at the W- on the old Persian Wheel. It involved the same orincip'e, but instead of using buckets hite keeps forcing the water through the spiral and to the outlet at the at one side of the wheel to lift the water, an extension arm center of the wheel. built in trough form leading to a center spout, served to raise the water, while the force of the stream on the back of the e,nuehs rotated the wheel. 1212 Science and Invention for, April, 1921 The Transit of Mercury The Planet Will Pass Between Earth and Sun May 7 BY DONALD IL MENZEL

A very good view of the moon occulting a star it photographed above. When the moon occults a star it disappears immediately since the moon has no atmosphere. The occulting of a star by the moon is used by mariners at sea for obtaining correct time.

a Above is shown a total eclipse of the sun observed at the Harvard Observa- tory August 7, 1869 The transit of a planet is practically the same thing but the planet does not obscure the face of the sun. On May 7 Mercury will pass across the sun in the same manner.

JUPITER PASSING ONE OF HIS MOONS

Above Jupiter is seen passing one of his own moons. This is an illustration of what will happen when Mercury makes his transit. Photo Harvard Observatory.

THE PL4NET SE A5 A BLACK DOT ON UNS SURF/IC In olden times when eclipses could he NORTH not predicted, panic was created by their appearance. It was a terrible thing to the ancients to see the face of the sun obscured during daylight hours. Many times it caused extreme fright, since it was considered a sign of the EARTH wrath of the Gods. FIRST C TACT AT MAY 7 MERCURY 4;32 EASTERN TIME w Immediately above is a diagram- e / S9 SUNSÉ4. matic scheme of the orbits of A7N - the earth and Mercury showing CHICAGO how the intersection of their sunset' planes, while both are in line AT DENVt with the sun, gives the effect of SUNSE - the transit. AT SAN FRANCISC S U N SUN

A transit of Venus is a much more beautiful sight. The planet has an extensive atmosphere so that the planet's disk is ringed with a pearly halo during its passage across the sun. Probably Mercury has little if any at- the planet's at At tee left is an illustration of transit mosphere. different points throughout the United States. The first contact will be at 4:32. Eastern Standard Time. Science and Invention for April, 1924 1213 Weather Legen 5 and overb5

One cf the oldsst weather legends is that a red sun A morning rainbow often leads sailors to look carefully Many farmers will tell you that the number of stars has water inside. The condition most favorable to a at the barometer. A morning rainbow means that the in a moon corona will indicate the number of days red setting sun is a large quantity of dust and smoke air is rather humid and rain is likely, for a shower has before the next rain. The corona itself is caused by particles in the air. These gather moisture and the occurred with but little rise of air and slight cooling, diffraction. Water droplets in the a.r cause the moon's haze so cased results in the sun's redness. leavino the water particles close to earth. corona

111//

That twinkling stars are a sure weather indication is The cause of fog is the cooling of the surface air to High clouds having required much cooling to form do one of the most tenacious proverbs known to weather a point below its dewpoint. In summer radiation may not contain enough humidity to produce any consider- prophets. Stars twinkle becacse of atmospheric dif- cause fog and in winter fogs are caused by an influx of able rain or snow. Therefore, the old proverb: "High ferences caused by foreign substances in the atmos- humid air from a body of water. Summer jogs in- clouds, fine weather" is substantially correct. The phere. Much dust or too will cause twirklinn. dicate fair weather winter ones n stornr woolsack or cumulus indicate fair weather.

L rr F Thunder has evoked few proverbs. About the only one Some people, it is said, can "smell rain." This is Lowering smoke is a well known indicator of foul When is is that spring thunder bring: a cold wave. There is due to the fact that an approaching storm brings with weather ahead. the air excessively humid little foundatioa for this proverb and itsorigin has it a rise in the pressure of the atmosphere of the small particles of moisture gather around the smoke no scientific foundation sirce thunder showers are earth's surface, releasing small amounts of the decay- particles as a nucleus and cause it to bear down much usually raused no the onward movement of Humid a.. ing oroaric oases which escape into the atmosohere- nearer the earth. In dry weather it is free and rises.

Day is rainy it is >_apned to pre- Another st,ano, onion which has nu scientific fosnoa- One of the most widely adhered to superstitions is If Saint Swithin's a of the rain for forty days-but tian is that those afflicted with neuralgic or rheu- that known as "Groundhog Day." Whence this old dict continuation its never has. The legend runs that pious people at- matic pains outer their illness more just previous to idea arose is a much disputed question, as it is quite tempted to move the body of the Saint on July 15 a storm than a_ any other tine. See "Weather Prov- obvious it has no foundation of any kind, says E. B. and that rained for forty days, preventing them. erbs and Parodies," by Dr. W. .1. Humphreys. Dunn, weather expert. it 1214 Science and Invention for Ap i1, 1924

alrhe Mg-wadeDys® By W. B.

BORDER engineers and the electricians who carried out Mr. Max Reinhardt's idea: in the LIGHTS THEproduct on of "The Miracle" at the Century Theatre in New York City, desove wide o o publicity and praise for surmounting the greatest obstacles that have ever confronted o CYCLORAMA American stage technicians. Above may be seen the archway which takes the place of O Oó0 7 O O the old-time proscenium. The whole theatre had to be rebuilt in the form of a L cathedral. The stage was entirely taken away and extended out into the autitorium O until the length of the stage is equal to the length of the auditorium- Bones had to SCOLUMNS IRUNWAY be torn out, all the side li hting and exits had to be covered and an enti -ely new O system of lighting in

HIDDEN ORGAN -

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This perspective view of the inside of the Century Theatre as it appears remodeled for this gigantic procuction, gives a clear idea of some of the problems which the stage technicians had to solve. A huge pipe organ had to be installed behind the stained plus windows, which appear high up above the second balcony. (These windows were made by painting the designs on a fine wire mesh.) The huge columns extend to the top of the theatre. They serve as scenery and as channels from which to slide the windows back of archway up out of the way w th change of scene. Stage property is handled be cables from gridiron.

CHE IIICAL POTS

LIGHTS

(c)i)24 a3Y SC. ENGE ei - /I YErY rK1N 4 At !re le't is .hown the altar In the insert at A is shown Chief which by 'ehe simple expedient of Electrician Eugene Braun and his being divided in the middle as stage director giving orders to the Moms, serves as co altar, a door- special switchboard, insert B. Note way and art imitation pipe organ in where the spotlights are located in each of three different scenes. the drawing at the top of the pape. Diredly above is shown a torch Immediately above is shown the stage bearer in ene of the mob scenes. manager who has a costume in which The ight cf the torch is furnished a microphone is attached for every by k.wo electric bulbs and the mob scene. At F is the tall tower omelet is from chemical pots. The extending to the top of the theatre. lighting cabtle a4taches to floor At G is a pulpit. D shows the smoke Plugs.. At C in the tap drawing is screen outlet; H are traps. E is a shown a companionway through heavy oaken doer. whict the cast sinters the staoe. 1216 Science and Invention for April, 1924 ProbLems Alir5hip Construction

TOP 5/DES OF GAS LAYER OF INERT GAS FABRIC BAGS PRESSRGR/NST OUTER THE FRAMEWORK SURROUND/NG GAS BAGS BULGED OUT

OUTER FRAME *' GA5 TANKS

Gasoline or luci 'ank., to reduce danger from

For the greatest 5- in the construe. By allowing the motors to exhaust into lion of airships it necessary if pos- the g. eat bag a layer of inert gas is sib'e to build the ship so that the gas formed completely around the periphery bags do not touch the framework, thus of the ballooets thus decreasing danger decreasing danger from lightning. from leaks and

HOGGING STRAIN

AIR N/R < POCKE;--

SAGGING STRAIN !r motif- tt te,04 woo"

<`POCRET . .

The dotted lines illustrate air currents. One catastrophe, that of the ZR -1. has caused the The strain they cause an the longitudinal employment of on'y skilled men for working an ,upporting structure of the ship is airship into her hangar. This is extremely obvious. These strains must be con- dangerous work and all girders must he padded. sidered at all times in the design.

a ship were tilted above a certain angle, whole of the gas bag equipment would '-ive to rush out of the upper end of the :rmework. This angle at present cannot be attained with safety.

It is much easier to moor a large aircraft to a mast than to work her into a hangar. A .ne is dreppeu [ram t su shiPl MOOR/NG is attached to a cable ao! MAST ie ship .,c!i a t[ -e MARK CIRCLE _MOOR/NG CABLE ON GROUND 4s FROM SA/A' CABLE WINCH \ HOUSE MOORING CABLE MEN COUPLIN6 FROM MAST C/eLES

M/N/MUM BREAK /KG STAN/N HERE

MOOR- NOSE ING EYE CAP MOOR/NG U YERSAt CABLE GU/ JOINT ROPES

To prevent serious damage there must be a -weakest in some part of the mooring point" The mast and mooring must be so constructed line so that if the ship breaks away no damage OP OF as ta allow the ship to ride facing the wind, will be done to her structure. This is a ver- AST Shewill stand a 60 m.p.h. wind- sion of an old expedient in mechanics / Science and Invention for April, 1924 1217 Insect ®1.11 S Now di e New Microphone Sensitive to Ultra Audio -Frequencies By W. W. RODGERS*

III,.. . b . ,... While searching for some new method Ly which the sound waves for radio broadcast stations might be pinked up with more clarity and accuracy than with the microphone used at present, the new glow microphone was perfected by Dr. Phillips Thomas. Although it has not yet been put to extended use in connection with broadcasting, it has opened a field to science which heretofore has been closed. It will pick up the minute sounds made by insects. In order to pick up the sounds of insects it will be necessary to suspend the microphone in a jar where the insects are confined and to pass the current from the microphone through an ordinary radio receiver. At the left is shown the glow microphone attached to a horn. Below Dr. Thomas is "hearing" one million vibrations per second.

The high frequency sounds are made audible through the use of the heterodyne effect, i.e., by causing the high frequency sounds picked up by the glow microphone (translated into an electric current) to be impressed on a radio receiver, and allowing a second The glow microphone is nothing more than two electrodes series of oscillations of nearly connected to a direct current source between which is placed the same frequency to inter- a third electrode, as shown below. Alf three electrodes are fere with them; the two os- mounted on an insulating ring. If the current is so adjusted cillations coming together that only a glow is produced across the electrodes instead of form an audible heat note, the usual direct current arc the instrument will be extremely which is similar to that heard sensitive to all variations of sound frequency striking it. in a regenerative radio set.

Micarta Below is shown the circuit which was used in testing the microphone for high frequencies. By impressing the oscillations of a high -frequency radio transmitter upon an arc, it was discovered To Source To kmpli£ier that the arc released the sound waves of the same frequency as the oscillations set up by the transmitter. By placing the microphone attached to a horn in the sound field of the arc, the high - frequency sounds generated were audible in the radio set. STANDARD ROPHONI, PICKING UP AUDIBLE .MODULATOR SOUNDS FROM PHONOGRAPH AND OSCILLATOR OUTLINE OF GLOW DISCHARGE MICROPHONE The Cu r,,,d unit .shows .,/, 7t i,v tern,od Crn"exploring c,lecrrode"

-.a...CONDENSERS BALLAST RESISTANCE ARC, GIVING FORTH MODULATED TO PREVENT HEAVY MGR FREQUENCY BOUNCS, (UP TO ARC ...... h Ì)b0,000 VIBRATIONS "ER SECOND `+ 1 NFW GLOW MICROPHONE

BALLAST RESISTANCE STANDARD RADIO RECEIVER the phonograph played into the I SIG, R.F,DET I In the tests with this circuit transmitter of a small were impressed upon AND tA.F. SOUND GATHERING radio set and the radio oscillations the arc as shown. At the HORN arc, however, the carrier wave frequency was changed into sound waves which, of the human ear. course, could not be heard by These high -frequency sounds had frequency sounds which impressed upon them the lower carried the tune from the music was phonograph. When the phonograph plainly heard in the radio receiver, -microphone was interpreting it was obvious that the glow the super -audible sounds.

* Of the Westinghouse Electric & Mfg. Cu. 1218 Science and Invention for .ipril, 1924 \ easuring r

4_, at

BV DR. C. G. ABBOT OF THE SMITHSONIAN INSTITUTION WASHINGTON, D. C.

Mt. Wilson Observatory has suc ceeded in measuring the heat of the different parts of the spectrum of stars. At the left is shown the method in which the sensitive PLAIN MIRROR measuring instruments were used. It will enable us to know more thoroughly the constitution or spectral distribution of the lights of different stars. Light from the CONCAVE GIANT MIRROR star reaches the great mirror, A, MIRRORS is reflected to B, thence to C, PRISM through focal point D to concave perforated mirror E. From this F - e -PLAIN point it is reflected to concave A Fi8 2 MIRRORS mirror F, returning through hole QUARTZ FIBER ANO LIGHT HEAT in E and strikes 60° glass prism BLUE RAYS P, producing spectrum which GREEN CONCAVE :(1-::;4-1":--' _ strikes radiometer I. MIRROR +-jRAOIOMETER J, YELLOW - S i RED`'.:,: GROUND GLASS 1111 r .,' " INFRA -REO Fig TO REALIZE / HP FROM i SCALE II III sit STAR CAPELLA, ALL HEAT SPECTRUM FALLING ON W. VIRGIN/A WOULD HAVE TO BE COLLECTED VANES E WINDOW f

RDA LAMP SLIT HEAT FROM SUN The above shows the sensitive instrument which measures the power of the light ON / SQ. YARD rays and their temperature. A quartz fibre, A, thinner than a spider's web carries I EARTH'S SURFACE vanes, B and C, a two and mirror D. A movable slot in front of the vane, C, SQUARE allows the EQUALS H. particular portion of the spectrum which is to have its heat measured YARD / P to fall on the vane. The heat force of the ray acting on the vane causes the mirror to rotate, twisting the fibre, and reflecting a beam of light from the in- candescent lamp, F, upon the ground glass scale, H.

Fig 3 Fi8 5 - VI 5/8LE INFRA -RED RIGEL O ò VEGA 2 5 4 SIRIUS PROCYON 9 SUN 900.000 MILES /F CAPELLA IS THIS LONG CAPELLA i ALDEBARAN 3 BETELGEUSE

Some idea as to the minuteness of the measurements made by 2 the Mt. Wilson astronomers may be gained by referring to Fig. 4. It has been ascertained that the heat of the sun falling on one square yard of the earths surface produces practically one horse-power, while to realize the same amount of power from a representative star of the first magnitude, Capella, the W whole area of the state of West Virginia would be necessary. PRI 5MA TIC DVSPE RS/ In Fig. 3 is illustrated the comparative heat of various stars 0 40' 20' 0 40' 20' D 20' with that of the sun. The line representing the heat of the 2 40' 10 20' 40' 20 20' 40' 3 sun would stretch away 900,000 miles if a line representing the from visible heat from Capella is one inch in length. solely their spectrum. Note that in the present measurements, in the case of the sun and Betelgeuse, These measurements, of course, are of the heat of the a large celes- portion of their heat curves fall in the invisible portion of the tial bodies affecting the earth. Some of them it has been well spectrum. Before the present established, measurements were made, as- are many times hotter than our own sun. Some tronomers long held the opinion that both Vega idea of the importance and Sirius of these measurements and of the in- should be considered blue -white hydrogen stars with few terest they excited in scientific circles, may be gained from the lines showing in their photographic spectrum. It was also chart at Fig. 5, which shows the heat curves of the stars in thought that they were both nearly twice as hot as our sun. both the visible and invisible portions of their spectra. Here- The new measurements disclosed that tofore the heat Vega's maximum heat was and contents of the stars had been judged nearer the violet end of spectrum than that of sun. Science and Invention for April, 1924 1219

®Hugs ew D ..vai vices

gun which, if it does not hit the burglar will at least scare him, is seen. A toaster which works on the same principle as the ordinary electric heater and A burglar A wire which operates the trigger stretches across a dark spot. The intruder strikes which can be used for hoiling eggs or doing other li2ht cooking is shown above. the wire, firing the gun. The coils are in the focus of the two parabolic reflectors at the sides.

No more will the unhappy householder have to rush out on The handy pctato peeler shown above is simply a rough acold morning to buy more tooth paste because the old tube carborundum stone corn pound placed in a tin receptacle on finger. has broken The above device keeps the tube intact. the back of which is sma!I loop which fits over the

The pistol grip on the screw driver above ullows the most recalcitrant s:rew to be forced into place with comparative ease.

The flashlight shown in the above photographs derives its power from a small The guard light shown above will be found particularly useful to those who do a dynamo in the handle which is operated from a spring motor. The motor is large amount of night driving on unfamiliar roads. it is installed under left fender wound up by rotating the outer sheath of the flashlight three times. and casts a beam of light 18 inches wide. It has red rear and green forward lights.

The motorist need no longer be late on account of a balky spark plug resisting all efforts of the driver to clean it. The A universal watch which Everyone knows that a disk of the proper weight dropped in spark plug shown above is built in three will give the hour in any part so of the world and at the same me a boiling kettle will rattle and ring. H ere this knowledge separate units and comes entirely apart ti standard observatory time by the simple expedient has been applied. It may be dropped in the kettle, and its that all the units are easily accessible. of turning a dial under the rattle will tall cook's attention, saving dish from boiling over. When assembled it is perfectly gas -tight. hour and minute hands, is shown above. 1220 Science and Invention for 1 pril, 1924 Tim y T ,- imepieces No. 1 of a Series. Hints on Maintenance By SAMUEL BERNARD z LTh

MAIN SPRING CENTER WHEEL BARREL HOUR ¿MINUTE ESCAPE HANDS CARRIED WHEEL OWCENTERSHAFT

4 = WHEEL /GERN/ES SECOND HAND) 9C^WNEEL

1 2 3

In the better grade of watches great care is taken to test If the timepiece in the pocket of an engineer on a In the final analysis a watch is nothing more than a train them thoroughly under every conceivable condition in which transcontinental train were not carefully adjusted for of gears which magnify the speed of the minute and hour they may be forced to operate in actual practice. Above all changes in temperature, the result would very prob- hands to an extent where they may be adjusted with more is shown one of the very important preliminary tests, that ably he a screaming headline in the daily press telling or less ease to the greatest possible accuracy. Above is of finding the watch's accuracy in various positions. It is of scores of deaths and terrible property losses. All shown such a train of gears and the method in which the laid face down, face up, and setting in a number of dif- manufacturers of watches which serve where exact time main spring which is the motor that runs the watch, is ferent angles which include all possible positions that the is a necessity, subject their product to the most severe attached to it. The train adjusts the speed of the minute watch may be forced to operate under while it rests in the temperature adjustments. As illustrated here each and hour hands. The small escape wheel governs the entire owner's pocket. Seme of these positions prove that there completed watch is placed in a case with a thermometer movement of the train. The fourth wheel just after the is a maladjustment in some part of the watch which would and is passed through the whole range of temperatures escape wheel, carries the second hand and makes one not otherwise be noted. It is also made to run with the from 40° below zero, Fahrenheit, to 120° above. At complete revolution to each sixtieth of a revolution the stem in a different position at each angle of test. of a number of temperatures the watch is readjusted. large center wheel carrying the minute hand.

CENTER BALANCE GUARD WHEEL P/N/ON STAFF ROLLER HOLE FOR RIVET- HAIR SPRING COLLET TABLE ING IN STAFF: ROLLER SET FRICTION TIGHT BALANCE WHEEL AXIS. ON BALANCE STAFF GUARD P/N FOLK HORNS

LEVER PALLET JEWELS

BALANCE END OF HAIR SPRING ARM FASTENED TO ESCAPE PINNED IN COCK OF WHEEL BALANCE COCK BALANCE WHEEL 4 5 6 7

All standard pocket timepieces have The heart of the watch is the escapement The modern balance wheel is made To the balance wheel shaft is attached a small spring a main spring. The outer end of movement which is shown above. As the of two metals similar to a ther- called the "hair spring" which with its forces the spring is attached to the barrel escape tension wheel rotates the two jeweled arms mostat and is finely balanced with the balance wheel to swing to which is toothed and is geared and fro. In the above to a move the lever to which they are at- a number of screws around its illustration is shown the method in which the spring is small pinion on the last wheel of the tached first in one direction and then in periphery. The bi -metallic con- attached, one end being made fast to the shaft and the gear chain which carries the minute the other, regulating the speed at which struction of the wheel allows for other to a small metal block called "the balance cock," and hour hands. The inner end of the the escapement wheel revolves and thereby temperature changes. A reduc- which is attached to the frame of the instrument. The spring is attached to the shaft which regulating the speed of the watch, since tion in temperature which would end of this spring which is works on a ratchet and is connected fast to the frame, usually the escapement wheel governs the train of cause the balance wheel to con- carries an adjustment by a separate chain of gears gears. for tension through which rough to the The pallet jewels prohibit wear, tract, and speed up is compen- adjustments stem of the may be made. It is this adjustment that watch, by means of which which would have a very definite effect on sated for by the bi -metallic con- the jeweler moves when you tell him your watch is run- the spring is rewound. the watch's a justment. struction, keeping the speed even. ning too fast or too slow.

A- C I PAN FULL OF BENZ/NE PUTT/NG OIL 8 /N O/L CUPS 9 B

Many a watch is thrown away because it liad a salt water bath. To prevent Wrist watches are notoriously poor time keepers. Always remove your wrist watch its being ruined the simple process illustrated above may be used. While the before taking a plunge. Water is very bad for marcello, so it must be infinitely watch is still wet or as shortly after the accident as is possible, open the case of more harmful to the delicately balanced mechanism of a fine wrist watch. Too, it the watch both back and front and immerse the whole mechanism in a tumbler of is not the best proposition in the world to allow a wrist watch to lie near an open machine oil. Allow the watch to remain in the oil for a, few days. After the watch window or over a hot radiator, or in fact, in any position where it will be subjected is thoroughly soaked in the heavy oil, remove it and rinse it thoroughly in a pan of to extreme temperatures. The same effect is inflicted on the watch by hitting it benzine which has been strained through chamois. After it has been thoroughly with an eight -ounce hammer as slamming it against the brass bed when one takes cleaned of the heavy oil by this method, allow it to rest in some undisturbed spot one's morning stretch. Obviously both methods of mistreatment should be studiously where there is no dust until the benzine is evaporated. Then oil each cup at the avoided if the watch is to be used as a time -keeper and not merely for ornamental top of the bearing shafts and put a very small drop of oil on the two pallet jewels. purposes. Science and Invention for April, 192E 1221 Magic for Everybod PROF. JO5EPH IDUNIMHGER

NO. 13 OF A SERIES

TABLE SPIDER - TOP DISC IRON SPIDER STRING BELT HOLLOW TABLE LEGS - FLOOR -y

GROOVED DISC UNDER THE FLOOR

claims they an statement he a ks any of them when they were born. If one of the audience On the table is found a zodiac with its signs painted thereon. The perform r places date were born in the month of March, the spider promptly stops at the sign for the iron spider upon the wheel and immediately the spider moves around and around on the mentioned. Its manipulation and the secret of its education is seen above. surface of the zodiac. He tells his audience that the spider is educate] and to prove his

COVER RED WHITE BLUE HAIR COIN y IIIIIIII IIIIIIIIIIIII

COIN lr

71f-rf (b HAI Rf one rests, thanks to a hair glued to the coin. If A coin is placed on the table and one of the audience instructed to place it under any of instantly under which the coin little the three cups, while the performer turns his back. On looking at the cups he can tell blindfolded the performer looks at the covers from beneath the blindfold.

---BRED HANDKERCHIEF BLUE TOP SAME AS BOTTOM HANDKERCHIEF RED SILK

BLUE SILK BOTTOM SAME

1 DIAGONAL AS TOP BOTTOM

The magician takes two match boxes out of his pocket. Into one of them lie stuffs a kerchief is now where the red one was, and vice versa. The match botes are peculiarly small red kerchief; into another a blue handkerchief is placed. Holding one in each constructed. Each has a diagonal partition with an opening on either side. The per - hand, he closes the boxes, and on opening them again it will be found that the blue former in closing the boxes, twists them so as to bring the opposite side to the top.

i( HOLLOW RING OPENS - ---t J PAPER AND ROLLED TUBE PAPER IS FINGER PLACED RING THEREIN +1/

merely a thin paper tube with a small quantity of tobacco at the end. It can con - A puff of smoke escapes from the magician's lips. He rolls up his sleeves and requests is be rolled a very small space and be vanished into a finger ring, the stone that two spectators hold his wrists. The lit cigarette is now placed in his hand, one sequently into be lifted up. The above tricks are very mystifying. hand rolled upon the other, and presto! the whole cigarette has vanished. The cigarette of which may 1222 Science and Invention for April, 1924 Ev ryd y Chemistry

By RAYMOND B. WAILES

HOW TO DETERMINE . WHAT CAUSES INKING PADS STARCH FILLING \ TO ALWAYS REMAIN MOIST? C+O = CO IN PIES, CUSTARDS ETC. CARBON + OXYGEN G/VES CARBON MONOX/DE= DEADLY POISON

11 'IMO I I C+ 20 =COz ,...... 4,

I I CARBON + OXYGEN CARBOND/OXIDE tlj. t 'iOU« - THE GAS /N SODAWRTER= ''."IODINE PALATABLE . g 1 _ j, \/ IIIII - a WATER n 1 IN GLASS 2 3 If starch is present in the filling of a custard pie, a Ink pads remain moist because the ink contains If one atom of carbon combines with one atom of part of the custard filling dissolved in a glass of cold glycerine and a dye. The glycerine never evaporates. oxygen it forms a molecule of a deadly gas called water will turn blue, if a drop or two of tincture of This keeps the pad damp. Your own stamp -pad ink carbon monoxide, in symbol CO. By combining one iodine is added to the water. When testing custard can be made by heating a cup of glycerine in boiling atom of carbon with two atoms of oxygen, carbon filling make sure that it does not contain any crust. water and stirring in a suitable water-soluble dye. dioxide is formed. We taste it in soda water.

A ROUGH "TEST" FOR 15 IT HEAT ALONE THAT MARBLE DUST IN CAUSES VARNISH AND DID YOU EVER SCOURING POWDERS PAINT TO NOTICE DRY? 4,--...e.---. - THE ,,%;':'.*,--' LILAC COLORED FLAME WHEN LIGHTING A CIGAR? I iiio i mo." 4 H.}- 6 To determine whether a scouring powder contains mar- Heat alone does not cause varnish and paint to dry. A lilac -colored flame, when lighting a cigar, is caused ble-dust, a few drops of acid from a storage battery It aids materially, however, by \ evaporating the solvent. by potassium salts in the tobacco plant. The tobacco are permitted to upon fall the powder. Marble dust It is the oxygen in the air which combines with cer- plant is rich in these compounds. Often a yellow will cause effervescence if present. It is not an tain substances in the paint to form hard semi- flame due to sodium masks the lilaccolored one, ' adulterant but gives scouring properties. elastic bodies, thus hardening the paint and varnishes. rendering it invisible.

EVER BEEN TEMPTED A ROOT WHICH COAL WILL BURN TO EAT THE KILLS COLD -BLOOD D WITHOUT APPLYING ¡ PASTE ? ,- ANIMALS BY _ I HEAT '' "' PARALYSIS -

j`" .ii1 _ t1. ' i ill Ziir i J r /q P '%Ille . l CARBON DIOXIDE GAS . 8 COAL Library paste sometimes seems good enough to eat, Many of the insect powders on the market due to the presence today are Coal will burn to some extent without being ignited of various oils, which are; added made of the flowers of pyrethrum plants, the active in- if it is finely powdered and placed in a stoppered to keep mould and the like from spoiling the paste. gredients of which cause the death of bugs by bottle; it will unite with the oxygen of the air in Spearmint, oil of cloves, wintergreen and other fungi- paralysis. Pyrethrum powder is urged instead of lead the bottle. This is really combustion but a flame or cidal substances are mixed with the paste. and arsenic insecticides which are deadly to man. light is not emitted. But the same products result.

WHY IS THIS WHAT CAUSES IS IRON THE HALF OF THE THE WEATHER ' I FLAME GIRL'S DRESS--= ONLY YELLOW TO CHANGE `{' A.-' MAGNETIC SUBSTANCE? COLOR ?" '` ` AND THIS `` III HALF BLUE? ro

le\v\11 ei H 10 11 , íj' 12 The inner flame is bluish and is caused by the l:ertain chemicals change color when the water of Iron is not hydrogen in the only substance attracted by the the gas which burns before the highly crystallization is removed. They revert to their magnet. The common metals nickel and cobalt, and carbonaceous gases also found in the gas. These latter original color, when it is added. The dress is soaked liquid oxygen are highly paramagnetic tending to take require more heat and air to burn them. in a solution of gelatin and cobalt chloride. a position parallel to the axis of a magnet. Science and Invention for April, 1924 1223 y Pens'f Eam 4 tch Trich5 a Mystifying Stunts Which Entertain BY WALTER B. GIBSON

OidÍtlllllllll0 á-11 S "s PUSH FIRMLY vmi AND UPWARD

of the One of the most mystifying stunts which can be per- the match box may be stuck to the door simply by this stunt, shown above, is a simple variation formed with a box of safety matches is sticking it to pressing it firmly against the wood, and at the same one shown in the first two illustrations, except that its back, a flat surface seemingly without any support. This time moving it upward. Several trials may be neces- the sanded edge of the box is used instead of stunt is performed with apparatus found around any sary before you can perform the trick. Either an and the box is supported from the coat sleeves instead with a home. Above, the match box is shown sticking to the empty or full box may be used. Press the box from sides of the door. A box of non -safety matches stunt. earl of an open door. The surface must be smooth. and corners, as pressure from the top will not work. sanded side is required in this

COIN BETWEEN COVER & DRAWER

BOX FALLS WITH COIN DOWN

Borrow a box of safety matches from a friend, shuffle Hurl a box of safety matches in the air. It lands on The secret of the trick just described lies in an old, hand, be very mysterious, and then tell which the table with the label side up. Repeat the whirl old law. It is performed by virtue of a heavy coin it in the way the heads of the matches are pointing. Your two or three times. The box always falls flat, label placed in the bottom of the box between the drawer results will be much more certain if the box of side up. The box may be whirled by someone else, and and the case. Preferably a heavy coin should be used. is a one, since the difference in the in spite of anything they do, if they actually throw the The weight of the coin causes the bottom of the box matches full weight of head end and tail end performs the trick. box into the air, the results will be the same. to fall downward.

/1 \-1. END WITH HEADS TILTS DOWNWARDS The mystery helps the effect, but the trick itself de- This stunt is not at all mystifying, but it will add A thumb tack is necessary for the performance of this pends entirely upon the good old law of gravitation. By greatly to any impromptu entertainment. Simply take stunt. It is thrust part way through the cover of a grasping the box in the center very lightly the added a handful of small safety matches and lay them out match box as illustrated and a match is made to stand weight of the heads of the matches will force one end on the table in some preconceived design. If the de- upright after the performer has made a lot of stage of the box lower than the other, thus giving an indica- sign is viewed through half closed eyes from some dis- business seeking to lead his audience to believe that tion of the direction of the heads. tance, its effect will be surprising. he is having trouble balancing the match on the box.

introducing the acrobatic flame. Light two matches, Here is a real puzzle. Break open the cover of a The solution of this trick is indeed clever. It is only necessary for blow one out and as the smoke curls up, hold the match box and set it so that it forms a sort of tun- the performer to cup his hand in such fashion flame of the other match above it. Suddenly the flame nel. Place the empty drawer of the box on the oppo- that it will reflect a stiff breath of air onto slides dawn the curl of smoke and relights the lower site side of the cover and then ask one of the audience the drawer. By this means the wind will act against - match. The lower match must be previously coated to bring the drawer through the tunnel without touching the drawer forcing it through the tunnel. With a slight with paraffine as an ordinary match will not work. it. The tunnel stands between him and the drawer. amount of practice this may be done with ease. 1224 Science and Invention for April, I921 e Heavens in nil By ISABEL M. LEWIS, M.A. of the U. S. Naval Observatory

* Ir MAGNITUDE * 2ND II * 3RD

{ 4TH II 5TH

Above is the star map for the month of April. If the chart is held over the head fifteenth the location of the stars in the heavens will coincide with their position on the with the "Northern Horizon," north, at nine P. M., April first or eight P. M., April map and may easily he found. Saturn is visible April fifteenth.

the first of April at nine o'clock in from Argo Navis on tie southwestern hori2 third magnitude. Diphda, or Cor Hydrae, the evening the constellations that zon to Cepheus now at the north point of the brightest star in Hydra and a star of the BYwe associate with the spring months the horizon, is inclined to the western hori- second magnitude stands very much alone are well above the eastern horizon zon at a low angle and is no longer seen at and a little to the west of the meridian and the constellations of winter are its best. at this time. fast disappearing from view in the west. Facing due south we see the extensive con- THE BIG DIPPER Perseus, Taurus and Orion are on or close stellation of Hydra stretching from a point to the western horizon. Sirius, The Dog - south of Cancer, where a small group of Turning to the northern heavens we find Star, is low in the southwest, Capella in faint stars mark the head, to the southeast- that Cepheus and Cassiopeia, two circum- Auriga, in the northwest. Castor and Pol- ern horizon. a distance of considerably more polar groups that were conspicuously in view lux, in Gemini, and Procyon in Canis Minor, than, ninety degrees. En the southeast, di- during the fall and winter months, are now The Lesser Dog, are still high in the west- rectly above Hydra, are the two small con- close to the northern horizon and are nc ern' sky and will he the last of ' the winter stellations of Crater, The, Cup, and Corvus, longer seen to advantage. Their places have groups to disappear. The Milky Way, The Crow, known as the riders of Hydra. been taken by the familiar Big Dipper in. the stretching in a broad band of faint light They contain no stars brighter than the (Continued on page 1258) Science and Invention for April, 1924 1225

MakIlng A TiraCceogicaph . GRAPHS OF DOUBLE SWING PENDULUM INTERESTING STUDY

Parts for universal joint Make2ofthese O cAssembly r 7e,:; /r ñ,. ó'l r; o -- (7 --7 A 3 E -m v 'v D e$s ÿ <-e Make4 of these Bolt hole N. Fasten Fwith -°i E metal plates ar/o leach:o these Bolt i F F Maké 4 oPthese 0 Table support parrs l' 24" H 18" --M © Apparatus i13" I complete <- 6 -> II Y- G"- rr 3 t_1/2i Tirt can /Jí re j< i F-10"L s Screw eye

I I, 11111111 iuu tullir About7lbs- unléi I,

Twisted 1 wM1 ndbber Swíng each weíghh o num U lrountaín pen support unm

the vertical and released simultaneously. The platform upon which the pape The traceograph, as shown in the above diagram, is very simply made, and the experi- away from and the pen (0) will draw various geometrical figures. Several menter should find no end of pleasure in operating it after it has been once constructed. is mounted (H) will swing samples of the work will be found on this page. -Constantine Troy. It win be seen that there are two weights on the traceograph, both of which are drawn

5pcec 3ec1uctIlon Gem-

PULLEY EMERY WHEEL ELECTRIC MOTOR BEL T

EMERY GRINDER SMALL DISCARDED PULLEY THUMB CRAM' SCREW TO /IO V CIRCUIT.

A belt around this A simple way to reduce the speed of an electric motor is to secure an ordinary emery the motor pulley. Remove the crank and substitute a pulley therefor. reduces speed wheel of the hand -driven type, pass a belt around the emery wheel and connect it with pulley wheel goes to the apparatus. A small motor pulley further. 1226 Science and Invention for April, 1924 hare Ct5 in e Th Suggestions of Use to Amateur Theatricals

By L. B. ROBBINS

a/h We are all familiar with the sight of torn bits of paper falling from above the stage in an attempt to simulate a snow- fall. Usually unless the scheme shown in the upper left corner is followed, the results are rather poor. The bits of paper either come dawn in bunches or the effect is spoiled in some other way. However, if a large slotted sheet is hung above the stage, as illustrated, the torn paper may be sifted out slowly. This gives rise to an exceed- Wooden ingly effective and natural result, which cannot be obtained box, by any other' simpler method.

An effective wind machine which depends upon the property of silk to squeak when rubbed may be made by following the suggestion given in the upper right corner. A weight holds Arc. the silk taut. By constructing a square wooden box and before nailing it up, placing in it a quantity of dried peas or shot, the effect of pelting rain may be produced. A sheet of thin iron suspended from a suitable support may be used to imitate thunder if it is grasped at the bottom and shaken violently. Artificial lightning may be made with an arc light, or by means of a photographer's magnesium flashlight. flcZsl

imitating water falls -rapids If an cascades elaborate stage setting depicting an earth- quake or other catastrophe wherein buildings are to be shattered is to be SCenery used, the noise accompanying such destruction can be furnished by means of a drum made as shown at the left, against which rest several wooden slats. These strips are to be held under tension so Canvas that as the druid is revolved they painted to will be forcibly thrown ímí tabe across the cross members of the drum. water

Hal f cocoanut The effect of water falling over sh eil rocks in the form of a cascade or Waves waterfall can he quite faithfully imi- tated by Constructing an apparatus i shown above at the right. Here three or more drums are used, over which ,i1V11ilUlW01WP is by hand. This : the canvas rolled i: : canvas is painted so as to give the appearance of water and the appara- illusion of allopíng horse:. Ston tus is concealed behind scenery, merely allowing the painted portion slab of the canvas to show through. The effect of waves breaking on a rock- bound shore can be produced by the _ .---- =Z. use of painted scenery and one stage Bucket of rock salt hand, as shown at the left. The assistant is located below the point where the waves are to break and \ periodically throws a few handsful of salt up. Two halves of cocoanut shells correctly manipulated on a stone slab give an excellent imitation of a galloping horse. /1,4.4(e. Science and Invention for April, 1924 1227 a: oat i Uses for' LarirowDD L5ccS Easily Constructed Home-Made Wig Articles Made from Discarded Discs

IVASHE/L NUT MUSHR0041ANCHO2 FAQ ROW BOAT EYE \\

OLD 'ROUND /RDN ROD 41 SHAFT CUT CROWN OF OLD DERBY HAT 8/RD BAS/N FORCE OR CH/CK _ FROM BRIM ON HEAD ..ntd TO LOCATE PLACE IVAT£R O/SH TO CUT LAG BOLT NUTS -AS FARM fNA/N BEIL MDUMED PAINTED FLESH ON S/DE OF COLOR HOIASE

S/MPLE FARM BELL

OLD SHOVEL HAND BOLTS COTTER, .1UA P/N /RON ROD RIP OLD HAIR STUFFED FINISHED CUSHION AND SEW HAIR WIG IN EMERGENCY SHOVEL AdeeANGED ON%'SQ. /RON TO PAINTED FOUNDATION USE RODAS 4/A/L E-2SEREII/ HOLDERS WHERE DESIRED discs farm harrow become dull they are thrown away. However, they An exceedingly simple yet effective wig for amateur theatricals giving the effect of a When the on the readily be put to numerous uses which will render them serviceable. Several bald head may be readily made by following the illustrations above. First cut the ran very are above. The discs are in most cases used in their original form crown from an old derby hat and shape it as shown. Then paint it flesh color and suggestions given case of the shovel, some drilling has to be done hair. This hair can. then be sewed around without drilling extra holes. le the from an old cushion obtain a quantity of -L. B. Robbins. the base of the wig or fastened in place by means of glue. -Charles T. Allen. to accommodate the handle.

Mwgnedc M1mCb§ IIIlilw2emüed iR efieceole

RU°38fR j0,,£Nf0

WOOL, BGOcn

The magnetic lines of force emanating from any forni of magnet are elusive things and one often wonders just exactly what they look like. Of course, the old hackneyed method of using iron filings gives some idea of the formation but still the illustration is only in a single plaie. In order to satisfy his curiosity as to Small mirror on elastic thumb stall the exact formation of these lines one resource- ful experimenter has produced results which are gratifying in the extreme. The photograph worn on left thumb to catch, at the left shows the actual formation of lines of force produced by this experimenter's and reflect 4l2t on scales me:hod. The lines show very clearly in the ice. in dark orshadoluedalaces

When measuring various castings or articles to be shaped on shop machines, there is not always sufficient light In order to reproduce the results shown in the photograph the magnet's keeper as shown, fill the can with water and directly on the rule or scale to provide easy reading. By wearing a thumb above, obtain a fairly large tin can. In the bottom of allow to freeze. The stresses caused possibly by difference stall with a mirror attached on the left thumb, may be this can place a permanent magnet in an upright position of expansion give an idea of so-called lines of force. light reflected on the scale. secured by means of a staple to a wooden block. Place -Clarence Ray. -Thomas H. Duffy. 1228 Science and Invention for April, 192I SiEhoue 1te ähadow Pictures Method for Making Shadow Pictures from Photos

gpmesemerserumemerneemee grew,rverr Mre" , ,,...tt .eazwmte.-ffluue;-eo,,e. . PLACE TRANSPARENT SHEET PHOTO PAINT IN BLACKS OVER, AND CUT OUT WHITES

BLACK MUST BE

i HOLD U TO LIG

PASTE ON WHITE SHEET

regular photograph, photographs that will make the person pictured stand out beautifully can be made by taking a white portions away. , SHADOWpainting the dark portions a solid black and then, with the aid of a very fine pen knife, cutting the are be made. If the As shown in the above sketches, the blacks are painted in in order to give the lines upon which the cuts to fine line around the border of the hair. After the cut-outs are made whole head is to stand out as in a profile view with dark background it will be necessary to cut a Although the scheme works very well if the cut-outs are made a white sheet is placed over the front of it and the whole placed where the light may shine through it. cardboard as this will make the contrast more clear. The same proof regular writing paper results will be found to be more satisfactory if they are made from light the layman to discover just where the light and shadows will fall. It cess may be pursued with a pencil drawing although it will take a little practice on t he part of used may not tear. is not necessary to demolish a good photograph will be found necessary to use a very fine pen knife in the operations in order that the paper It as cutting the original photo. Gruntal. in making the pictures since a tracing may be taken off the original and substituted with the saine effect -A. r -r

WeeQIlng iIcycUe Minh.

that weeping fish appear in the NOTannals of natural history. Not quite! At least, they do not appear outside the accounts of Jules Verne or the Baron Munchhausen. But that is no reason why they may not be made. Carve the fish or crocodile out of wood and weight him with shot or small lead slugs so that he will swim instead of float. Then color the body to look like the original. Then bore a small hole through the pupils of the eyes clear through the body. This done, fill the small hole with crushed water color or other pigment that will dissolve in water. Thrust a small piece of gauze or duck in each end of the hole to keep the color in. When the fish is placed in water the most beautiful streams of tears will come from the eyes and float gentry to the bot- If bicycle touring with a friend and you suffer a mishap tom of the water. -Dr. Albert Neuberger. with the front wheel why not simply remove the wheel and set the fork over the back axle of the friend's bicycle in the manner shown, forming a tandem? Science and Invention for April, 1924 1229

,/,r` IHI

iI01gpNN''laall r- ak' 1 .....,...... ,.,....,...,,...... ,..f....UcJ'i\FTo'AÀK

This department will award the following monthly prizes: First prize, $15.00; second prize, $10.00; third prize, $5.00. The purpose of this department is to stimulate experimenters toward accomplishing new things with old apparatus or old material, and for the most useful, practical and original idea submitted to the Editors of this department a monthly series of prizes will be awarded. For the best idea submitted a prize of $15.00 is awarded; for the second best idea a $10.00 prize, and for the third best a prize of $5.00. The article need not be very elaborate, and rough sketches are sufficient. We will make the mechanical drawings. Use only one side of sheet. Make sketches on separate sheets. CooRer Plant Cups r Teter FIRST PRIZE $15 SECOND PRIZE $10 THIRD PRIZE $5 2U" IIIIÌtI

árod -funnel

Dripping faucet/ 11 wood plug

1k4"" 111, /í4" OW gauze Z.6

Sprouting seeds In box Seed/itt planted -Bot//c Jv/thcupr 1 Priá/ring g/ass foie/ gauze For the early spring gardener the above kink will tie found exceptionally useful. Such plants as tomatoes and cabbages which have to he reset, are often retarded in their growth by ,such resetting. If cups are made of ordinary newspaper print paper with the aid of the form illustrated above, and the seeds of the plant sprouted A novel comparative ammeter is illustrated above. in the cups, the gardener will be well repaid for his work It By placing a funnel over a bottle to be cooled, setting consists of nothing more than a thermometer around whose in constructing the form by the advanced growth of the the bottle on a tumbler, tying the arrangement together bulb have been wound a few turns of resistance wire. pant. The block and the plug used to form the cups with gauze and allowing water from an ordinary cold The bulb and wire are then embedded in a small square may be made in any dimensions desirable. Two or three water faucet to drip slowly over it, as shown, evaporation container which is filled with asbestos cement. The rise different sized blocks may be used in the same press. will keep the contents of the bottle quite cold. in the thermometer will be directly proportional to the -Dale R. Van Horn. -J. M. Kendall. current passed through the resistance. -Simon Cherry. Mncrotone ScnSsoII°s Cheap Push Pin

SC/SSo2. EDGES

P/LOT WOOD HANDLE D/PfCT/ON By imbedding a phonograph needle in sealing wax in a small cartridge shell, as illustrated above, a very efficient OF BLADES' (?UBBE( T/P. a and very cheap push pin results. Lewis M. Baldwin. Ai't gn{fficIla1 Cndar GEARED RuBBEQ TIRED DR/t(üHJffL GEA2E0 , r -K class tube__

7 ONE PIECE STEEL fig.1 SMALL GEAR SOLID IV/TH 81A0ES COPIrs 7 -CAPPED AXLE BEARING //V ONE SIDE OF ONE PIECE FRAME' //./i a`.,,.,, yf/ ß£L hS {F. i, i " 'í:l+ ,Á1.-i%///Y/.Ni, %T `7. From those who do a great deal of cutting, the mechanical Ammonium carbneate Colon moist neb scissors illustrated above. will find a happy reception. The rotating blades are geared to the large wheel which pieces di/v/e ipdroc, /or/c Many experimenters using a microscope will at once see has a rubber tire and is fixed to the handle of the ma- acid. the value of the microtone shown above for slicing speci- chine which is made of an old scissor's blade. As the f/g2 mens. The thickness of the cut is regulated by nut H, wheel runs along the counter or table, the blades revolve which adjusts the height of the safety razor blade G. cutting the heaviest cloth. The fixed blade acts as a By covering a glass tube with cigar wrapper and using Specimen is imbedded in wax and held in the cup C. guide, feeding the cloth to the rotating blades. corks and chemicals as shown, a harmless artificial cigar -E. H. Swanson. -Thomas H. Duffy. is made. -S. Marchese. 1230 Science and Invention for April, 1924

ffsffss

.r.r,r.r.r..r..Rr.r.rs.r....r.r.r.rt..c..ci..r..r.r.:s.+r.'..r.r'r+Ti .^./`:..a..cr.V` R .i^

Edited by S. GERNSBACK

Test Tube Scale Coins As Weights CL.,. il7%1 nbject9

e e

'Scale written i on card.

U.Srcófns as weight Snap clothespin glued on cardboard ubstance tobeweiglel,

411

A scale drawn on a white card and glued to a spring A nickel weighs 5 grams, a dime 21/2 grams, a quarter 61/4 Dissolve as much alum as possible in boiling water. While clothespin as shown above makes a Jiandy scale for measur- grams, half dollar 121/2 grams and a silver dollar 26.7 still hot place any desired article in the solution as illus. ing the depth of solutions in a test tube.-Carlyle Weiss. grams. They can be used as shown above. trated above. Crystal of alum will form thereon. -Harry R. Lubcke. -Carolyn H. Gault. aubber Connector rush ., eceptacle Wall 'Protector \ xx`xxxxwx`x1.?w1r rfaee.e` % ,.. . ì,'7ü//%Gíi.

Paintbrushes \ .. Wi r e laid flat Rubber Lube

VIVIIIIIII,JIIIII I Q l'1111 11111111111 0 Glass tube

`H1Ìí1

Galiòn varnish confront Board rest which corners haspbeen Cut SwitChboara. Waite table oil cloth A handy receptacle Win ing wire around a rubber tube which is used for con - for paint brushes which will keep them nec ng together two glass tubes in laboratory work will in place and preserve them is illustrated above. Water or prey nt the rubber tubing from flattening out when bent. other preservative liquid is used. -L. B. Robbins. The wall around a switch very often becomes smudged with -William Tredwell. finger marks. A piece of white oil cloth placed as shown above will eliminate this trouble. -W. T. Markowski, Keeping Cern Fresh Preserving Flowers Umbrella Repaired

rStringorwíre Cob is tied ti hag upside down

least At Water to I of flower- which 15 'rains stems in. water of camphor is added Corn on the cob can be kept fresh for quite a long time If 10 to 20 grains of gum camphor are added to the When the thin wire that holds the steel stays of an um - by placing it in a bag upside down and tying the mouth water in which cut flowers are placed and the water is brella breaks, an ordinary paper clip may be used to of the bag as illustrated above. kept cool they will remain fresh for a long time. repair it. Only a pair of pliers are needed. -Wm. H. Seitzinger, Reporter No. 3826 -Win. H. Seitzinger, Reporter No. 3826. -Robert Lee Bird. Science and Invention for April, 1924 1231 n

io lEqui UTC A Complete Broadcasting Station for Religious Work BY J. F. ODENBACH*

The broadcasting of church services, sermons and hymns is by no means new to the radio public, but the actual It is an undisputed fact installation of a complete that the introduction of radio and up-to-date broadcasting broadcasting to the churches station in a church is some- throughout this country has what of a novelty. How- resulted in a greater interest ever, Aimee Semple Mac- being manifested in religion. Pherson, the woman evangel- Many people who formerly ist known throughout the were not consistent church country, has just completed goers have become converted the installation of broadcast- and every Sunday morning ing apparatus in her Angelus finds them at the radio set Temple, Los Angeles, Cali- tuning in on the service of fornia, and will shortly be- some nearby or far -away gin broadcasting her sermons church. It is now possible and the music of her choir to select your own sermon for the express benefit of and if the one you happen to listeners -in. Miss MacPher- be listening to doesn't quite son, in undertaking this suit your desires, you only work has not done any of it need to turn the dials and by halves, but has gone in listen to some other station. to the erection of her radio Usually, however, up to this station with an enthusiasm time the broadcasting has which assures it a complete been clone more or less success. Proof of this may spasmodically and little or be had by glancing at the no effort has been put forth two illustrations of the an- to place broadcasting as an tenna installation at the top integral part of the church. of this page and another at Many churches have in- the voice amplifier and other stalled radio transmitters apparatus shown in the il- heretofore, but usually they lustration at the right. The were of very low power and photo shows Miss MacPher- most of them have been dis- son at the microphone. continued. This one is undoubtedly permanent.

. Reporter No. 10 for April, 1924 1232 Science and Invention

Cuba and San A'ranci«.o Linked by Radio and Telephone Science and Invention for April, 1924 1233 ortabLe RacIlo 5et C. New Loop

At the left will be seen a new portable radio receiving set which is being used by the Berlin police for obtaining aid during riots and for receiving orders while on duty. This apparatus, while compact, has been found to be very efficient. Above is shown a novel loop which works on the principle of the variometer. The photo shows Mr. M. W. Ober - miller, the inventor, with his new loop. The interior coil is pivoted so that it may be turned at any angle desired in relation to the stationary outside winding. If desired, one coil may be used as the primary and the other as a feedback coil.

Soirne Note§' on N.seil-(31

1 /nsu/otioq tube Connection /uys 6/ass filledrni/h 0, Washer saphur -, Nuts We// W0'// ji Washer --I j / 4 ru n Binding Post Lead -ire i Porce%ire tube Cal Brass rod Binding i esheet arc/And corner threadede Posts ,' ¡ removedat both e in foi/ f to fi/e ends ® oh each side ®, 0 Of Wiiidoepane notches

At 1 will be seen the conventional type of lead-in employing a porcelain tube. At connections., At 3 is shown the condenser type of lead-in. At 4 is shown a method 2 is shown a more efficient type using a brass rod with binding posts at each end for of cutting out a corner of a glass window- ane and filing a notch therein.

insulated canducfing strp Window 1././a/es fa Affer ro//in4 dio Window d 1 /nsu/afirl ends in hot wo X Sash I 1 I tubes or for i, Ïlli _ lid Fe 0 - ° C Ie= --

/ flexible - strip 11Ér Severn/ /avers of Died 5//k .l : , , Window s/// or taae_ra//ed tight/ // Board as /any as {Yidth Of W//Id0[y '

At 5 is a flexible insulating strip to bring a lead-in through a window. No holes as illustrated. At 6 is shown another very good method wherein a board about 6 or notcnes are necessary. In the window frame it will take the farm of the casing inches wide and as long as the width of the window is placed in the casing. Science and Invention for April, 1924 Searchlight Causes Fading

DAYLIGHT 'NICHT RANGE ,RAN GE ION FIELD ---^--

EARTH

i OiATtltti O t s s r3ECE1V'NG SET

A unique application of the fact tfat radio waves travel better through darkness searchlight from the Forest Hill aviation field playing about the surrounding coun- than through light was recently b'ougnt forth by an amateur radio fan of the Middle tryside. Listening in on his receiving set to station KSD and watching the search- West. This amateur was located, as pictured above, some distance from broadcasting light at the same time, he noticed that whenever the rays of the light were directed station KSD. He was operating a s cryst'l receiving set and one night noticed across a line passing between his antenna and the broadcasting station. the signal that the signals faded considerably. This h..ppened at regular intervals and of strength was reduced in a marked degree. The results noted seemed to be very course called for an investigation, a, the weakness of reception seemed to differ much in accordance with former observations covering the difference between day- somewhat from the usual fading due ro atmospheric conditions. Looking out of the time ana night reception. The difference in signal strength is probably due to the window, Mr. Louis Robin, the amateur who had noticed this peculiarity saw a ionizing effect of light. -C. Doville Walker, Reporter No. 577.

SEI.F®C®NTAINEI) PORTABLE RECEIVER

A radio company of the Middle West has recently put on the market one of the most complete and compact self-contained receiving sets which has come to our attention in same time. Most of the portable sets which have been put out of late utilize only one or two or at the most three tubes. However, the manufacturers of this set, called the Operadio, have placed therein six vacuum tubes and use a circuit giving three stages of radio frequency amplification, a vacuum tube detector and two stages of audio frequency amplification. Thus a set capable of operating on a loop antenna and reproducing signals with sufficient strength to operate a loud speaker is obtained. The set is entirely self-contained, including both A" and "B" batteries, the loop antenna and the loud talker. One of the most novel features of this receiving set and one which to our knowledge has never been brought forth before is the location of the loop aerial. As will be noticed at the left, the loop antenna winding is entirely contained within two sections of the case which are hinged together and which when closed form the top and one side of the container or carrying case. A handle is fitted for quick and easy transportation and a plug is provided by means of which the antenna can be placed on the top of the apparatus when ready for use and at the same time connection is also made between the loop antenna and the receiving set. The completed set folded up is shown in the photograph at the right. The wire of the loop is indicated by dotted lines in the photograph at left. Science and Invention for April, 1924 1'35 c© Ma

o At stations WJZ and WJY New York City there is in use a newly developed device for indicating in a visual manner the quantity of modulation being used in the outgoing an. tenna circuit. The instrument is built on the order of the standard oscillograph and it gives the operator in charge a very good check, not on the quality of modulation but on the quantity. The quality of the outgoing signals is determined by monitoring sets through which the signals are reproduced in exactly the same manner as they would be in receiving stations throughout the country. The entire instruments used for detecting the quantity of modulation is illustrated at the left. Here A indicates a lamp housing containing an electric light; B indicates the point at which a prism is located for bending the light rays; C, shows three sets of tungsten wires supporting small mirrors any one of which can be used when desired; D, points to the slit in the box through which the light from the lamp is reflected by the mirrors; E, shows a four sided revolving mirror which reflects upon the scale, the light coming through the slot. The light ray coming through the slot, 0, moves backward and forward over the revolving mirror, whence it is reflected to the scale and an indication of the degree of the modulation is given.

1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 111111111 11 1 111 1 1 1 11111 1Z.1111111111111,,,1 1,,,11111111,,, 1 1 1 1 1 1 1 11111111111111111 At the right is shown a photograph of the collector apparatus used in connection with the visual modulator shown at the left. In this photograph, A indicates the lead-in from the transmitting antenna passing through a pick-up coil B which in turn is connected to a standard radio receiving set indicated by C. Leads go from the latter to the device shown in the photograph at the left.

1 TO RECEIVING SET PR/SM MAGNET

REVOLVING GROUND GLASS MIRROR COVERING SLOT MIRROR TUNGS TEN W/RES o

the pulsation of the current received. Thus the The photograph at the left shows a close-up view of the apparatus in unison with reflect the light beam. A diagram- holding the reflecting and vibrating mirror which is used in the mirror is made to vibrate and is shown directly above. As oscillograph shown in the upper left corner. At the left, A indi- matic view of the entire oscillograph light beam from the lamp to the prism, is cates two tungsten wires suspended and arranged with adjusting will he noticed the goes the mirror where it is reflected through the screws while B indicates a tiny mirror fastened to these two wires. bent or reflected toward upon the revolving mirror and back to the scale. The The two wires pass through between the opposite poles of a permanent ground glass is exaggerated in certain parts so as to make the action or an electro -magnet as the case may he. Current passing through diagram clearer. the two tungsten wires from the receiving set cause them to twist

EffieIlenü CfcyMaR neceeIlver

TO AERIAL extremely efficient crystal re- LOADING COIL. 40 TURNS An a vario -coupler and a 10" C.C. WIRE ceiver using SHORT ANTENNA OF Ne. 26 the tuning / WOUNO ONDA 3' NA. UBE variable condenser for SWITCH SHAFT , POST has been designed by the writer HOLE ^ / g / and a circuit diagram of the same is shown at the left. A loading the circuit and . coil is included in w+ovt1s so that = two binding posts provided _p when a short antenna is used the in loading coil may be included I YAaIQ COUPLER CONDENSER the circuit or it may be cut out T SEwFT. SHAFT HOLE em- r when a long aerial is to be ployed. Any type of standard i` ONO may be used in this '.TE vario -coupler NNA and it may have one or POST circuit, two switches on the stator. In the latter case, the lead from the antenna will go to the second switch arm. In order to make sharp tuning possible, a small is connected variable condenser DETECTOR" - rotor of the coupler. STANDARD across the HOLES _, 3f -- VARIO -COUPLER Any standard type crystal de- -.--34: l'---, tector may be used. -Gilbert Billin. PANEL LAYOUT TO GROUND 1236 Science and Invention for April, 1924 Crystal Set Loud T.:.11ter

AERIAL AERIAL? HIGH RESISTANCE / LOVO riVAR6RI0 LEAK 7ALRER STEEL VAR. AND EON .00025 'ICROPHONE STEEL CON. VAR. CON REED - BOiION ALEO .0005 Le_ f .A

TUBE MO ACTUATING REID ALISA TINL COILS COILS FIELD FIELD MAGNET MAGNET COILS LOOS-,

VARIO COUPLER LOW RESISTANCE BROWA''OR ANY VARIO COUPLER TEE-OP TRANSFORMER SWITCH OTHER LOUD SWITCH SPEAKING PHONE CRYSTAL DETECTOR

GROUND

6 VTS. 4 DRY CELLS

I PERMANENT MAGNET A REED C '- _---- ALUMINUM DIAPHRAGM

At last a device has been brought out by an English concern which sells for approxi- Magnavox, the field magnets are energized by the dry cells and other coils are wound mately the same price as a two -stage audio frequency amplifier and will allow the on the same magnets as shown for actuating the steel reeds. This microphone relay operation of a loud speaker with a crystal detector. Contrary to the standard two - device is shown in unit form in the insert. At A in the lower left corner of the above stage amplifier, it has very little upkeep cost, it only being necessary to replace the illustration is shown the complete unit containing both a loud talker and the micro four dry cells used, occasionally. Of course, this same amplifier can be used on a phonic relay. At B is shown a new type of loud speaking receiver manufactured by vacuum tube detector with a corresponding increase in receiving range and volume. the same company. The working mechanism of this instrument is shown at C in the Both of the circuit diagrams are shown above. This device operates on the principle lower righthand corner. An aluminum diaphragm in conical form is used, which gives of an electro -magnet actuating a steel reed. This reed in turn sets up vibrations in a excellent reproduction of received signals. In the loud speaking receiver shown at B microphone button, which cause a loud speaker to give forth sounds in accordance with the permanent magnet illustrated in C forms the base of the instrument and serves to the vibrations of the steel reed. On somewhat the lime principle as the well-known support the magnet coils and the rest of the mechanism.

ressi®n Type Rheostat

BAhe/ite Knob 4 a- L Nut So/dered fo sfri,o /"" I /II 2 S 1 4

I 4 4-Zatap 4I,L L elf -spie Brass Cup 4 regu/reo' Brass spira/ spring Z reguired

Brass To ass /"" 47.2e thread mach/he Screws Brass - I I/ /II

/II r-31 a, Ti6T ,,, 4j` 147 Cardbgord1 Cardbaard1 thick I 4 reguired ?required 4 I h'o% 6/ass Boiter baugqe.. j"/Iole tuóe i /6 /5" i 1,4 8 ' `Bo/t-e/itB to pass , machine "screwsscrews

In the operation of detector tubes, which are usually of the gaseous type, it is necessary to A threaded brass rod and a knob to fit are then provided. Next, from 14 -inch brass cut have a critical adjustment of the amount of current supplied to the filament. Even in the the two end pieces to the dimension shown and solder a nut in the center of one. The case of amplifiers it is sometimes advisable to have such a device. A rheostat capable of assembly is made as follows: Bolt one of the brass cups and a spring binding post to the operating in this manner can readily be made by the amateur from the working drawing bottom support, insulating the cup and the post from the brass strip. Place a spiral and the photograph shown above. The first requisite is a piece of glass boiler gauge spring in the cup and invert another cup over the other end of the spring. Place the glass tubing or fiber tubing Y. inch, inside diameter, by 2',4 inches long. Next, four brass tubing over the assembly made thus far and pour in a quantity of granulated carbon or a cups % inch or slightly less in diameter by about is or V4 of an inch long. Six card- mixture of granulated carbon and copper filings. Add two more cardboard discs and board washers of the sizes indicated above should then be obtained and V4 -inch holes cut another cup. Insert the other spring and the fourth cup. Continue the assembly as in the center of each one. Bakelite discs of the dimension shown will also be necessary. shown in the photograph at the right above. -Armstrong Perry. Science and Inz,enti,.n fnr .11,1;1, 10.' / 1237

Rad.Ilo Set n, d1:, ®nogra h Combinations Complete Receiving Sets in Phonograph Cabinets

11J;211111111I I '; 11I ìiïï;Illllißii

In the center photograph above is shown a complete A radio receiving set especially designed to be placed (view of a phonograph containing the Radiola 9 in the in any one of several styles of phonograph cabinets lid. The tuning controls are readily accessible and has recently been produced by the Radio Corporation since U. V.-199 tubes are used, they are not in the of America. This set, which is illustrated in the way when the lid is closed. The photographs directly photograph herewith, is so constructed that it is above and to the left show the same type of receiving comparatively thin and therefore can be placed in the set included in two different types of period models lid of a standard phonograph, as shown directly of phonographs. In either of the two latter cases, above. In this way it does not interfere with the there is plenty of room far the location of the bat- operation of the phonograph and when the radio set teries directly back or below the receiving set proper. is to be used, a loud speaking unit can be attached This receiving set is designed to operate on an out- to the end of the tone arm of the phonograph and side aerial and only two tuning controls are used. the acoustic qualities of the phonograph horn can be These are seen to be two variable condensers. There utilized for reproduction of music and sounds. Thou- is a small coupling coil placed between the primary sands of dollars have been spent for research work in and secondary tuning inductances and connected direct- the construction of phonograph horns and it is well ly to the ground. This is found to aid materially in to make use of the fine qualities of the units such as tuning. Instead of connecting the potentiometer in are now produced. In this way an excellent loud its usual position, across the "A" battery, it is con- talker can be had without any very great expense. nected in series with the negative side of it and As will be seen in the photograph above, the nec- thence through a variable condenser and the secondary essary battery leads are brought out from one corner inductance to the grid of the first radio frequency of the receiving set panel and can be brought down amplifier. A "C" battery of 4I/2 volts is used to in back of the phonograph cabinet to the batteries. place a negative potential on the grids of the second If desired, and if room is available a still more com- radio frequency amplifier and the two audio fre- pact unit could be made by placing the "A" and quency amplifiers. The cores of the audio frequency ''B" batteries in the cabinet provided for records. If amplifying transformers are connected together and this is not desired, or space cannot be given over to to the ground. Two shading or neutralizing coils the batte -es, a small box could readily be made and are wound around the two radio frequency trans- placed directly alongside the cabinet, where the bat- formers and unilaterally connected to the filament teries could be placed and concealed from sight. circuit. By moving the switch indicated, better Binding posts on the top of the box would provide a control of the radio frequency amplification can be convenient method of connecting. obtained.

G. L. , Coup/ing coil 1.238 Science and Invention for April, 1924 lectiv Receivers-Fro

By A. P. PECK, Associate Member

L 300 L e00

Hrr . oo H(.co/a .ap.000

The cry of today from the radio bugs seems to be almost entirely for greater selectivity and hence, better "DX" work. The receiver illustrated in perspective in Fig. 1 and schematically in Fig. lA is undoubtedly one of the most selective when properly constructed and operated. It is of the most talked about Armstrong Super -Heterodyne type, employing three stages of radio frequency amplification. If desired, audio frequency amplification can be added in the standard manner. Coil A has 35 turns. B has 40 and C only 8.

Neuiroformer,

o Many people using Neutrodyne receivers would like to use them with a á 00 loop antenna, but they usually do not obtain very good results when the first Neutroformer is included in the circuit. However, excellent results Loop both as to selectivity and "DX" work can be got with a loop antenna UN 2A on surh a set by disconnecting entirely the first Neutroformer and using 00 the circuit shown in Fig. 2 and 2A. Any standard Neutrodyne can be used in this way and no radiation will be experienced. .s-vore +I+11181011108-1.-I + 224v z

TYarriio Coupler

+22% V.

Next in order of selectivity to the Super -Heterodyne and the Neutro - dyne comes the tuned radio frequency amplifier illustrated in Fig. 3 and 3A. The tuned impedance coil is very simply made and the data is given in the schematic diagram. If desired, the circuit shown in Por/ the lower righthand corner may be used for the antenna tuning by connecting the points marked X to those marked in the same manner ;Tor ul the complete diagram. This. however, reduces selectivity. Science and Invention tor April, 1924 1239 rh' st t

INSTITUTE OF RADIO ENGINEERS

Honey Comb Coils

gives excellent results when A variation of the tuned plate method of obtaining regeneration is shown above. The three honeycomb coil receiver illustrated above wave -length. Selec- This set is very simple in construction, but it must he handled very carefully tuned properly. The sizes of the coils depends upon the variable condenser across tickler coil. in order to prevent radiation and the consequent interference with nearby sets. tivity is increased by placing a

SW 3

Va rio Coupler 70005 r 1il1-v If there are no nearby local stations to interfere, a set constructed and hooked The set illustrated above is very quiet in operation because of the fact that no up as shown in the above circuit diagram will give excellent results for "DX" regeneration is used. It is about on a par with the circuit shown in the lower work and will be very quiet in operation. Vario -coupler helps selectivity. right hand corner but will give louder signals. Its operation is very stable.

Honey Comb Coil

A crystal detector when hooked up as shown A vacuum tube detector with a single tuned antenna Probably the least selective of all sets is the reception above will give quite good selectivity; in fact, circuit is not very selective, but for only single tuned crystal detector circuit illustrated this is one of the best crystal circuits. for local stations it may be found desirable. above. It is good for local stations only.

Science and Invention for ,I pril, 1924 1241

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. NEUTRODYNE CIRCUIT MULTI -WAVE COUPLER SUPPORT A. 1. A microphone similar in constru- (239) Richard Jackson, New York City, (241) Geo. A. Patterson, Wichita Falls, tion to an ordinary telephone transmitter asks: Texas, asks: may be used for this work and we illus- Q. 1. Is it possible to make a Neutro - Q. 1. In reference to the multi -wave trate herewith a cross-section of such a

dyne set using only three vacuum tubes? Reinartz receiver described in the December transmitter showing the component . parts.

TO AERIAL -NEUTRAULNG CAPACITIES- - -- .0003 MF VARIABLE PHONES, TO PRIMARY, ' CONDENSER WINDING 70 PRIMARY WINDING TO PRI. WINDING

r 1 VACUUM TUBE sA GRID LEAS 2 MEGOHMS

SEC. GRID F WINDING CONDENSER 0003 MF VARIABLE .00025 MF. CONDENSER

RHEOSTAT

TO GROUND

....-NEUTRALIZING CAPACITIES AERIAL

NEUTROFORMER NEUTROFORMER o . o Pa F gS. eni E 0003 2

NEUTROFORMER B) - A A' BATTERI' 45 TO V GROUND I11)UpUUIIUppf + 90 S. BATTERY --

Q. 239. The circuit diagrams above show all the necessary connections for a three circuit is aperiodic while the secondary circuit and the secondaries of the seconu an tube Neutrodyne receiver using Neutroformers with tapped secondaries. The antenna third Neutroformers are tuned. The two diagrams above both show the same set. A. 1. This is entirely possible, but you issue of SCIENCE AND INVENTION, what A. C. HUM will not be able to use a loud speaker on the length will the sides of the metal support same except possibly for the (243) L. R. Forney, Fort Benning, Ga., powerful local for the rotor have to be? submits stations. Such set, however, is a circuit diagram of his receiving a an excel- A. 1. The length of the sides of the sup- set states lent "DX" receiver for use with head phones and that it gives very good report for the rotor and stator of the multi - sults. He says, however, that he is con- and a circuit diagram with all the data there- wave coupler you mention will depend en- stantly on is given in these columns. troubled by a persistent hum which tirely upon the size of the coifs employed. at times almost drowns out the reception. This could be very readily ascertained by He asks: obtaining your GROUNDED LOOP two coils, mounting the rod Q. 1. Can you suggest the cause and (240) J. H. M. Beaty, Chester, S. C., in the rotor and placing it in its relative posi- method of eliminating this hum? asks: tion to the stator. The measurements can A. 1. We believe that your trouble arises Q. 1. What is meant by a grounded loop? then be taken directly. not in your receiving set itself, but from in- A. 1. A grounded loop antenna usually duction from nearby power lines. We would refers to a standard loop which is connected Small diaphragm to suggest that you investigate this and if you to a ground. By retain granular carbon find doing this, signal strength and carry carbon your aerial lead-in passing near a line will be increased somewhat, but selectivity button electrode, / carrying alternating current, you should will be greatly reduced. cover the former with insulation, place a Q. 2. If I tap a coil wound on a 3/ inch shield over the insulation and ground the lat- tube every 10 turns, will a variable conden- ter. Other than this, there is practically no ser with a capacity of .0005 mf. shunted method of eliminating the hum without the across the coil take care of the tuning be- use of quite an elaborate choke coil and con- tween these taps? denser system. A. 2. Yes. In fact a coil consisting of Q. 2. I have considerable 'trouble with 40 turns of No. 22 D. C. C. wire on a 3/ howling and squealing when the second stage inch tube without any taps whatsoever will of audio frequency amplification is used. cover the band of broadcasting wavelengths Can you help me toward eliminating this when shunted by a .0005 mf. variable con- trouble? denser. A. 2. Regarding the howling obtained in Q. 3. When a coil is to be tuned by means Q. 242. Above: A cross-section view of a standard your second stage, we would suggest that of a parallel condenser, what is the highest elephone microphone employing carbon granules for vary you try shunting a .0005 mf. condenser across capacity that should be used? ng the current in accordance with the fluctuations of the secondary of the second audio frequency 3. the voice. A. In placing a condenser in parallel transformer as well as one with a . capacity with an inductance coil a capacity of no more THE INTERIOR OF A MICRO- of .001 mf. across the primary; of . the first than .0005 mf. should be used so as to pre- PHONE audio frequency transformer. serve the correct relationship between the in- (242) Robert Bailey, San Francisco, Sometimes a twb rnegohm grid leak will ductance and the capacity. When it is found Calif., wants to know : give better results than the small, fi -ed'con- that a station cannot he tuned in with the Q. 1. How is the interior of a micro- denser across the secondary"óf"tlie,seeond .0005 mf. condenser at maximum, the amount phone such as used in radiophone transmis- transformer. ,Both. arrangements'shoïlld he of inductance should be increased. sion arranged? tried, one at a time. .

IIri

WANTED ! ! ! RADIO ARTICLES 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 satisfactory. portant parts and make pencil or pen and ink sketches of the We want articles on the latest single tube receptors which re - hook -ups or mechanical details, et cetera. We are particularly quire a minimum current from the filament battery.-Editor.

...... ,.Ir11rr...1111111111111111.1,1.1 ..,.,.,. .r.r...rrrrr ...... ,,r.....r..r.r...r,..,..r.,,rrrrrr.rrrrrrrr.rrlrlrrr,r111r.rr.I,.r, I,rr.,rrll..r11,.,,r. r.11.11muumuu ,,1,,,1,.I,.r,. 1r11..1.r...1,..1.111111.111.11111.11111.1111.111rr...r...... 1111,1. 1242 Science and Invention for April, 1924

CAPACITIVELY COUPLED your detector tube, "A" and "B" batteries A. 1. The circuit for this work appears RECEIVER and phones. You should not have the least in these columns. trouble in making this type of set work, and (244) Arthur Greene, Portland, Me., you can operate it, and at the same time R. F. WITH TWO CIRCUIT TUNER asks: notice the various characteristics of your (247) Ross Kirberg, Ness City, Kansas, Q. 1. What is the simplest circuit for use detector tube, which are shown during the asks:

TO AERIAL TO AERIAL .0005 ME VARIABLE RADIO FREQUENCY PHONES CONDENSER TRANSFORMER 001 MF VARIABLE GRID LEAK & CONDENSER CONE)?

0005 ME VARIABLE CONDENSER

s/ HONEYCOMB COILS .0005 MF VAR CONDENSER 'B'BATT 45-90V TO GROUND TO CROUND

diagram above shows a Q. 244. The circuit capacitively coupled tuner using a crystal Q. 247. A two circuit tuner which does not employ regeneration will be made much detector for rectification. This circuit may be quite sharply tuned. more sensitive by adding one stage of R. F. as shown above.

with a crystal detector which will come operation of the set. You will also be able Q. 1. Can you give me a circuit diagram tinder the head of a capacitively coupled re- to learn how to tune this particular type for connecting one stage of radio frequency ceiving set? of tuner. After you get this set working amplification with a two honeycomb coil A. 1. You will find in these columns a well, and have thoroughly mastered the tun- tuner? circuit diagram showing how two variable ing, and adjustment of the detector tube, A. 1. The diagram you request is given condensers .and 2 two -slide tuning coils may you are ready to add one step of amplifica- in these columns. be connected to give very good results as a tion. Try this for a while, and then add capacitively coupled receiver. your second step. We are sure that you will. then obtain the desired results. QUERY ON VARIO -COUPLER POOR RECEPTION (248) Alex Maderia, Erie, Penn., refers (245) D. C. McBride, Winchester, Tenn., to a circuit diagram published in this magazine in which two connections were shown states that he has made a receiving set, but AERIAL is unable to get any results from the same. to the stator of a vario-coupler. He states He asks our advice on this subject and that he has a coupler, but it is of a differ- requests some suel;estions as to how to ent style, having fourteen taps on the pri- overcome his trouble. CRYSTAL mary or stator. The coupler pictured in the A. 1. In the first place, we would sug- DETECTOR magazine had taps every tenth turn only. gest that you try reversing the polarity of He asks: your "A" battery. Some tubes work best Q. 1. How can I hook up to this vario - with the negative side of the "B" battery coupler ? to the positive of the "A" battery, and some .001 MF FIXED A. 1. The connections to your vario - with negative to negative. CONDENSER coupler will depend upon the style you have Another thing is that we would not advise on hand. In all probability, your 14 tap you to use the open circuit jacks which you f vario -coupler is tapped 7 times in tens, and indicate in your diagram, because when your } 7 times in units. If such is the case, you TO END I will connect all the tens taps to the points phone plug is in the jack for the detector OF COIL tube, you will find that your phones are of one 7 -point switch, and the units to the 1 shunted by the entire resistance of the prim- THREE SLIDE points of the other 7 -point switch. One ary of the amplifying transformer. When TUNING COIL switch arm is then connected to the aerial the plug is in the first step jack, the phones condenser, and the other to the ground. are in series with the entire resistance of the TO GROUND primary of the second amplifying transformer. In either case the results obtained Q 246. A three slide tuner will give quite good resu is ANTIQUATED TUNING COIL will be greatly inferior to those obtained when used with a crystal detector as shown above. The s lectivity would be improved by placing a variable con- (249) Norman Peterson, Concord, Calif., when using two -circuit jacks. s nser across the two sliders which are connected to the describes a tuning coil, wound with hare In his experience, the editor has always detector and phones. copper wire and mounted so that it may he found that when building up a new set it is revolved. He then proposes to make con- much better to start with just the tuner THREE SLIDE TUNER CIRCUIT tact with the wire by turning the coil and and the detector and to addllater one or two (246) Gilbert Marks, London Mills, Ill., having- a slider follow the convolutions of steps of amplification. We would advise requests : wire. He asks: that if you do not obtain the desired results Q. 1. Can you give me a circuit diagram Q. 1. Would such a coil be of value? otherwise, that you try this. Just hook up showing how to connect up a standard three A. 1. The idea you have was used in the your variable condenser, variocoupler, vari- slide tuning coil, a crystal detector and a original Marconi installations. It makes a ometers, and grid leak and condenser with fixed condenser? very cumbersome apparatus.

200 ILLUSTRATIONS -100 ARTICLES is the average of every issue of RADIO NEWS. We doubt if appeals to all factions: the Scientist, the Amateur, the Experi- there is a radio magazine in print that can show the diversity menter, the Broadcast Listener, and the Manufacturer. Each of articles and illustrations that is found in this maga- will find articles written especially for him. Every issue of zine. RADIO NEWS is a radio education by itself. Sold on 35,000 But above all, it is the quality of the material that is of newsstands in the United States and in every international book prime importance to the man interested in radio. RADIO NEWS store in every civilized country the world over. INTERESTING ARTICLES APPEARING IN THE APRIL ISSUE OF "RADIO NEWS" The Shenandoah's Radio Installation, Loud Speakers and How They Work, Oscillating Crystals for Wavemeter Calibra- By S. R. Winters tion, By Russell G. Harris Standardizing the Ultra Radio Frequencies, By E. Alexander Neutrodyning Audio Frequency Amplifiers, By Francis W. Dunmore and Francis H. Engel Recent Novelties in Thermionic Tubes for By Clyde J. Fitch Wireless Achievement and Anticipation, Radio Work-Part II, Getting the Most Out of the Small Trans- By Sir Oliver Lodgs By J. A. Fleming, M.A., D.Sc., F.R.S. mitter, By Brainard Foote Science and Invention for April, 1924 1243

Pazeán _° System Air Propelled Vessel Psychic IIns4rument

_Old style ship " Air bubbles Air/ .-New st le Compressor olor

No. 1,475,393 issued to H. A. J. De B. Nachenius. In those vessels which are propelled by gas or air discharged below the water level, a substantially plain surface forms the stern face of the vessel. As the bubbles pass upward the vessel is, of course, propelled in a forward direction, but due to a wave formation a lot of energy is lost be- No. 1.473,369 issued to M. S. F. Williams and John K. cause the air must lift the water above the surface. The E. Dilfenderffer. It frequently happens that the space at stern of the vessel is so curved that the top of its curve street curb or the side of a road is sufficient to accom- conforms with the water level making it impossible to lift modate an automobile, but is not sufficient to allow the the water. fame to be steered into place by the usual manipulation No. 1,476,158 issued to Grover C Haffner. In the psychic the of the steering and driving mechanisms, or sometimes instrument shown above a board is so mounted that it can so close to owner of the automobile finds the cars parked easily be tilted. A pointer is mounted un the table in out. urglar Alarm him that it is impossible for him to drive his 'car such a manner that when the ouija board is tilted the With the present system attached to an automobile this BATTERIES pointer will move from right to left across the face of special will always be possible. Four wheels placed on a the board. In the operation of the device two people sit chassis beneath the car body are first driven downwardly .r/ _BELL in front of the board, as indicated in the above sketch. lacking the up, en pwer is applied When placing the hands upon the board, it is impossible the acar tor o movnd e utout sideways from curb. to maintain it in a relativley fixed position. Consequently the pointer will be found to move whenever the table is tilted in a clockwise direction. Photo °Taphác Gauge Lemon Squeezer \ CONTACTS

SAFE

No. 1,472,750 issued to James F. Gorman and Frank C. Gorman. Whenever the door of the safe shown above is opened an insulating pin which holds the two contacts open, slips out of position between these contacts. The latter close the circuit to a bell conveniently situated. Aircraft Hangar

No. 1,469,415 issued to Walter F. Herzbe g. In taking pictures it is quite necessary that the development of the issued to Peter Juergensen. In tke illus- negative continue until it has been normally developed, No. 1,469,514 a dish is provided with a series of regardless of whether the negative has been under or over- tration shown above and are joined by a disk at the exposed. Intensifiers, reducers and such means are used in rods which extend upward center of this disk a rod extends. order to bring out the contrast in the negatives, but the top. Through the a tubular member may be found hav- amateur photographer finds it difficult to determine exactly Surrounding the rod ing a of diverging arms, whose lower portions when his negative has been normally developed. The in- plurality inwardly directed arms. This tubular member may ventor of this system places a series of indices alongside have be rotated freely. When the knob on top of the device is of the negative with the letters U, N and 0 appearing pushed downward, the pointed arms are caused to embed thereon, representing respectively under -developed, normally themselves into the sides of the lemon. When so firmly developed and over -developed. The letters are treated with embedded the hand wheel is rotated. This causes the chemicals in such a manner that they appear progressively houses lemon to turn on a knob -shaped device at the bottom of as the development is continued, and therefore, when the No. 1,470,557 issued to Ivan I. Eremeeff. Three the dish, whose sides are arranged with ribs or corruga- solution weakens due to use, the letter N will not appear are mounted on wheels and rails provided. When assembled from the lemon is thus thoroughly re- development has been carried on long enough to the hangar resembles a T, having one section for the tions. The juice until soiling the hands. produce a normal negative. fuselage and right and left for each set of wings. moved without 1244 Science and Invention for April, 1924

a c©enta , c THE LATEST HIT THE CORRECT "HOOK-UP" Firot PTti ze One Sunday morning, Mr. Gray felt an DROPPING PARACHUTIST (to himself) : $3.00 urge to do a bit of carpentering in connec- "There seems to be something wrong with AN ALARMING INVENTION my patent parachute, but I will hit upon tion with his receiving set. After the something presently !"-S. H. Harrison. "What's this family and the good neighbors next door new invention were safely off to church, he got out his AND SO KOP SPELLS POLICE o f yours ? " tools and had a busy time. When the new asked the pro- \ra shelf was screwed up, the grid -leak over- TEACHER (conducting first year spelling moter. hauled, and all the connections tightened, he class) : Can any little boy or girl spell a turned up the rheostat and twiddled the dials. new word for us? Its an up- to-date alarm - From the loud speaker came a solemn, min- SON OF RADIO FAN (raising hand) : I can isterial voice, spell Pittsburgh. clock," replied t h e inventor. "Remember the Sabbath day, to keep it TEACHER: How do you spell Pittsburgh? "You will no- - holy !"-Mrs. J. W. Swain. LITTLE BOY : K D K Radsch. A.-Robert tice that in- AN EVEN DRAW SOME NEW HOOK-UPS NEED ONE stead of a bell it has a bugle that blows reveille."- ANGRY CUS- AUNT ENNA: I..1 O'Connell. TOMER: This cigar "Is Ralph very you sold me re- 4Lj stupid ?" A CELLEBRATED JOKE fuses to draw. D. TECKTOR: ISAAC: Veil, PROFESSOR : "Who can tell me what a "Stupid ! Why he's mine good friend, tissue is?" did you tink dat I so dumb he thinks STUDENT: "A tissue is a collection of a radio fan is an would furnish you cells all of which are similar." vit a suction pump apparatus used to PROFESSOR: "Now illustrate." keep a receiving for only five cents? STUDENT : "A prison !"-Francis Sielski. set from becoming Daniel C. MacLeod. overheated." - Ir - ven K. Rimbey. WE receive daily from one to WHY JOKE EDITORS DIE YOUNG two hundred contributions to PROFESSOR: "What proof have you to INTEREST this department. Of these show that convulsion is contagious?" OF GREAT only one or two are available. We A number of men were having a discus- STUDENT: "When our baby goes into desire to publish only scientific humor convulsions my mother gets a fit." sion as to who was the greatest inventor. and all contributions should be origi- some said Marconi, and PROF.: "Now, tell me what other name Some said Edison, nal if possible. Do not copy jokes they some said Morse, while still others said dif- call a tumor?" from old books or other publications STUDE.: "Can't sir." ferent men were. as they have little or no chance here. Finally, a small German got in a word PROF.: "Correct." By scientific humor we paean only such PROF.: "What kind of organ is the and said : jokes as contain something of a scien- "Veli, chentlemens, dose vas great peoples. trachea?" interest tific nature. Note our prize winners. STUDE.: "A pipe organ." but I tell you, de man vot invented Write each joke on a separate sheet vas no slouch.-T. H. Buescher. PROF.: "Have you read any articles on and sign your name and address to it. salt ?" Write only on one side of sheet. No STUDE.: "Yes. Lot's." THIS IS STATION E.V.E. letters acknowledged unless postage is PROF.: "Do you know what organ catarrh "Radio is one of the first things mentioned included. effects ?" in the Bible." All jokes published here are paid STUDE.: "No, sir" (nose, sir). "What do you mean?" for at the rate of one dollar each, be- PROF.: "A very good answer."-George "Well it says there that Adam made a sides the first prize of three dollars Fuller. loud speaker out of a spare part." for the best jokes submitted each raised month. that two people "Uh huh ! And the loud speaker In the event A GOOD CATCH Cain, I suppose."-A. Zimmerman. send in the same joke so as to "tie" for the prize, then the sum of three The train jerked BRAIN dollars in cash will be paid to each one. to a sudden stop. WATER ON THE The brakeman hurried through to During an exper- "BODY CAPACITY" the rear end to dir- iment flight a SAM : "You look worried today, Bill." flag. A smart igible was struck BILL: "Yes, I took my girl to an ice young gent blurted by a sudden storm, cream parlor last night and she ate four out, "Hey there, and wrecked. The quarts of ice cream." brakie, what's the friends of a cer- SAM : "Well, did that make you go broke matter? Did one tain professor who and become worried?" of Henry Ford's had been a passen- BILL : "No, I can't solve how a girl can masterpieces park itself on the track?" ger were greatly eat so much ice cream." "No," replied the brakeman. "The matter alarmed, "For," they said, "he would natur- SAM : "Well, well, you just pick up an is not as serious. The cow -catcher had a ally forget to pull the release cord of his arithmetic book and you will find that four calf." Neil Miller. parachute." quarts equals one gal. (gallon)."-A. J. A subsequent report found this to be the Lozouski. A POSITIVE ANSWER case, but added: "He had been pondering a question dur- JIGGs : "Are you an amateur photog- ing the flight and as he fell he became aware WE'LL CONDENSE THIS JOKE TO rapher ?" that the rain on his head annoyed him. But 10 CENTS, Editor S. & I. JAGGS: "No. Why do you ask?" JIGGs : "I heard that you would serve EDITOR : you'll have condense this got Miss Film - he reflected that his parachute Say, to star's negative as an umbrella, pulled the cord, and descend- article. last night."-John H. Schalek. ed in safety."-W. L. Hastry, Jr. SCIENTIST : It's already condensed. EDITOR: What's it about? RADIO FLATTERY TO BE BOILED IN 'OHM JUICE SCIENTIST: Steam. C. S. Garrison. A radio fan named McSlattery Turned on too much juice from his battery; SPARK : "Think I'll go trouble shootin'." Then tuned and-Great Scott ! GAPP : "An' kilowatt ?" INSULATED The noises he got : "Oh, some aqueducts, maybe."- SPARK "Oh, I wish I Were like Amateur Night in a cattery.- Joseph M. Straughan. could find some Mrs. J. W. Swain. place where I LET HIM TRY IT WITH A PIPE OF could be cut off QUO VADIS? PEACE entirely from the TEACHER: What's the difference between JONES : "I only use smokeless tobacco." world." an explosion and a collision? BROWN: "What kind is that?" "Try a telephone STUDENT : Well, in a collision you're here, JONES : "Chewing."-Henry B. Daven- booth." - Victor and in an explosion where are you ?-M. D. port. Trapani. Johnson. Science and Invention for April, 1924 1245

S¡/ ,si'./!''''LlRdI'''Jy'i/.YytC/'''lYL'LLL''''LL''''L' L'''.r''''LL''LL'Y'LLy''./.YYy'dd'''r'trL't4C/ytr/' 9

The "Oracle" is for the sole benefit of all scientific students. 3. Sketches, diagrams, etc., must be on separate sheets. Questions Questions will be answered here for the benefit of all but only matter of addressed to the department cannot be answered by mail free of charge. sufficient interest will be published. Rules under which questions will be 4. If a quick answer is desired by mail, a nominal charge of 25 answered: cents is made for each question. If the questions entail considerable I. Only three questions can be submitted to be answered. research work or intricate calculations a special rate will be charged. Cor- 2. Only one side of sheet to be written on; matter must be type- respondents will be informed as to the fee before such questions are written or else written in ink, no penciled matter considered. answered.

SPARK PLUG CONSTRUCTION ditions under discussion. The short right angle GRAVITY CELL cushion in the following man- (1645) Charles T. Praser, Bronx. N. Y., says: arm acts as an air (1648) Richard Falk, Wantagh, L. L, asks: ner. When the faucet is open, the water starts for "A" claims that the center electrode in a spark full If now the faucet Q. 1. Can you give me directions setting plug is molded in the porcelain. "B" claims that flowing out at a strength. up and operating a gravity cell? it is inserted after the porcelain has been molded. is suddenly closed, the water tends to keep on flowing and would bump the end of the pipe with A. 1. To set up a gravity cell, place the cop- Q. 1. Which is correct? per electrode in the bottom and completely cover A. 1. B is correct. The baking temperature it with a saturated solution of copper sulphate in for porcelain is so high that the metal electrode is usually advisable to have a quantity would fuse during the process. water. It Where pressure of copper sulphate crystals lying in the bottom high in a state TELEGRAPH CIRCUIT water systems are of the jar, so as to keep the solution used it is necessary of constant saturation. On top of this solution, (1646) A. Dansen, Chicago, Ill., says that he to have an air which occupies about three-quarters of the jar, is has connected up a telegraph line with a neigh- cushion in the pipe carefully poured a weak solution of zinc sulphate bor's house, but the current flowing through the line as shown at in water, so that the two will only slowly mix. line is so weak that it will not operate a sounder the left. This pre- The saturated solution of copper sulphate being at one end of the line when the key is closed at vents damage to denser will remain on the bottom unless agitated, the other end. He asks: the pipe as de- and will only gradually rise to the top. In the Q. I. How can I connect a relay and a local scribed in the text. zinc sulphate solution suspend the zinc electrode. battery in this circuit so that satisfactory results If the copper sulphate solution reaches the zinc, can be obtained? 1111111111,11111111111111111111111111111t111, metallic copper is precipitated on it causing local A. 1. The circuit diagram for this work is action and polarization. given herewith. The relay, capable of working on considerable force if the cushion were not pro- These batteries deteriorate more quickly if kept a small current, closes a local circuit and the vided. The well known "water hammer" works on an open circuit than if kept in use, and they local battery actuates the sounder. on this principle and even in household installa- are, therefore, generally used in closed circuit tions it has been found that this shock is some- burglar alarms, telegraphy and other closed circuit times sufficient to burst the pipe. For this reason, work. the air space shown is included in the pipe system so that the cushion will take up enough of r the When a force to prevent breakage of the pipe. compara- 111111.111111111111111111111111111111111111111 tively long e I e - t m11,,,,,m,,,mn,n,n,,,m,,,,,,,,,,,,,111111m111,,,,m,,,,,,,,,,,,,,,,,,,,,,,,,1 ,,,,mn1,mn111n,,,,11,,,111111 graph line is used, the current at the Interesting At the right will receiving end i s Articles to Appear be seen diagrams very seldom suffi- showing the various cient to operate a in April Issue of types of lenses in standard sounder. common use. The A B C In this case, it is "Practical Electrics" lenses in the illus- necessary to employ tration are all let- a relay, which op- Odd Telephones, By Clyde J. Fitch tered and the terms erates on a low Analogises and Others, used to designate current, to close By T. O'Conor Sloane, Ph.D. the various lenses local battery cir- Detection of Icebergs are given in the cuit as shown, at Rival text. the left. Austrian of Franklin Infra -Red Light Telephony; 411.11111111111111111111111111111111.., By Jacques ,,,,,, n,,,,,,,,,,,,,,,,,,,,,, 1 11 1 1, 1n, Boyer (Paris Correspondent) D E F Building a Thermo-galvanometer Electric Oil Feed for House Furnace, A HYDRAULIC QUERY By George E. McVicker LENSES Antonio, Texas, says Farm Windmill Electric Plant (1647) Harry Jackson, San R. S. asks' that he has very often noticed that on a water Hot -Wire Ammeter (1649) K. Mitchell, Annadale, I., faucet for a Q. I. Kindly illustrate and name six of the pipe, the pipe itself extends past a Cigarette Holder and Lighter short distance and turns at right angles, where, common types of lenses. after continuing for another short distance the Cable Guided Ocean Liner, A. 1. We give herewith illustrations of lenses end of the pipe is capped. He asks: By Raymond F. Yates as requested. Lens A is a double convex, B, Q. 1. What is the reason for this extra length Conning and Enlarging Machine, plane -convex, C, concave -convex or meniscus, D, of pipe? By Roy Hale double concave, E, plane -concave, F, convex con- A. 1. The diagram herewith shows the concave.

uuunuuuuuunuuuu11unnnnunnununun,,,muununnnunnmuuuuuuuuunun,,,,mn11,n,,,,n11111nn1..11nn11mnnn111,,, OUR $12,000 PRIZE CONTEST IT will be noted from recent issues and the present one new material that can be written up for SCIENCE AND IN - that our prize contest has been a whale of a success. Over VENTION. And the formula is simple-just keep your eyes $1,000 has been paid out this month for worth while contribu- open. Even if you were totally deaf or blind, you could still tions to SCIENCE AND INVENTION, either in pictures, win a prize by simply using your head and sending us ideas of suggestions, ideas or articles. We now have on our staff, close a scientific nature, or of a nature directly or indirectly attached to 9,000 correspondent reporters who are scouting the world for to new inventions.

,,,,11,,,,,,,,,,,,,,,,,,,1111,1,,1111,,,,,,,,,,,,,,,,,.,,,,,,,,,,,,,,,.,,,.,,,,,,,,n111,1,1,,1,111,,,,,,,,,,,,,,,, INTERESTING ARTICLES TO APPEAR IN MAY ISSUE OF "SCIENCE AND INVENTION" Animal Eating Plants. By Dr. Ernest Bade Cigar Box Contest "Prize Awards" Double Decked Railways of Tomorrow. Alps Mountain Railway-Remarkable Photos Timing Cannons Electrically. By George F. Murphy and Diagrams. By Raymond Francis Yates Aspects of Interstellar Communication. Artificial Creation of Life. Plant Experiments in the Home. By Chevalier de Terrail By John F. Mazur and Dr. E. Bade By Dr. Russel G. Harris, Jefferson Physical Distortion Photographs. By S. H. Samuels Laboratory, Harvard University. The Infinite Vision. By Charles C. Winn Electric Marionettes. Fishing with Hydrogen Balloons. Odd Uses for Paper. Painted Movie Scenes Rival Natural Settings. Daylight Saving in Ancient Rome. By Ismar Ginsburg, B.S., Chem. Eng. By Tamar Lane By Charles Beecher Bunnell ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

nm,,,,,,,,,,,,,,,,,1111111,111111111111111..,,,nm,,,,,,,,,,,,,,,,,1,..11,...n.n,,, 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 words 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. Address all inquiries of this nature to INFORMATION EDITOR c/o Science and Invention, 53 Park Place, New York City. 111111 m11,,,,,,,,mm,,,,,,,,,,,,,,,11111111...... 11.MMM11mn,m,,,,,,,,,,,,,,,,,,1111,,,,,,,1,1,11,.n, ,,,,nmmm,,,11mm,mmnnm,nn11nnn11l,mmMmeninin,,,,,,,,,11mm 1246 Science and Invention for April, 1924 SAND BATH GAS IN FLAME THE D'ARSONVAL GALVANOMETER (1650) J. W. Mahoney, Elizabeth, New Jersey, (1654) Frank Fischer, Milwaukee, Wis., re- (1657) Maurice Rolhouzen, San Jose, Calif., re- asks: quests: quests: Q. 1. Can you give directions for making a Q. 1. How can it be demonstrated that there Q. 1. Upon what principle does a d'Arsonval sand bath for use in heating chemicals and state is a certain amount of unburned inflammable gas galvanometer operate? the reason for its use? present in the flame of a candle? A. 1. The d'Arsonval galvanometer operates on A. 1. Our illustration herewith shows how a A. 1. If the flame of a lighted candle is exam- a principle very similar to the electric motor. The sand bath should be set up. The iron receptacle ined it will be found that there is a bright yellow current passing through a coil of wire very deli- is supported on a tripod over a Bunsen burner outer cone and a darker inner cone. This inner cately suspended, sets up a magnetic field which and partly filled with sand. The flask or other interacts with the field of a permanent magnet container to be heated is imbedded slightly in the and causes the coil to twist to one side or the sand other. Our illustration herewith shows a simplified and the burner lighted. The advantage of a tommlontomminnntruumum sand bath is that an even heat is supplied to the view of such an instrument. A small mirror is flask and danger of breaking it from sudden In the center of a mounted on one of the supporting wires. If a cur- changes of temperature is avoided. candle flame there rent is passed through the coil it will twist either is a certain amount to the right or to the left and the mirror will move. of inflammable gas present which is not burned because uttuttglumunnumnuntrrtuun 11111111111111111111111111111111111111111111 oxygen cannot get At the left is to it through the The principle of the shown the correct outer part of the d'Arsonval galvano- method of setting flame. This can be meter is illustrated up a sand bath for proven as shown at at the right and use when heating the left. described in the chemicals text. A which ,11111111111111111,1,11111111u11,1111, mirror is must be carefully placed on the sup- treated. The uses porting wire so as of the sand bath to provide cone is composed of gas, a method are given in the but cannot burn because of indicating the text. air does not reach it through the outer or lumin- amount of rotation. ous sheath. If a small metal tube is placed in the unnnnnnnnnnnunnnuuuuum flame so that one end of it is in this dark cone and a match is applied to the other end of the tube. a flame will be seen at this end. The unburned gas is conducted through the tube and burns read- By directing a light beam upon the mirror, the RECOVERY OF SILVER FROM PHOTO- ily at the other end. exact degree of its rotation can GRAPHIC NEGATIVES measuring be determined by 111111111111111111111111111111111111111111111111111111111111111,11111 1111 11111111111111111111111111111111111111111111111111111111111 the angle over which the reflected beans (1651) W. J. LaChapelle, San Francisco, Cal., of light passes. asks the Oracle: IMPORTANT Q. 1. Can the silver contained in the emulsion WAVE POWER MACHINE used on photographic negatives be recovered? TO NEWSSTAND READERS (1658) Anthony P. Giancano, Brooklyn, A. 1. It is entirely possible to recover the sil- IN order to eliminate all waste and un- York, asks: New ver from photographic negatives. The process is sold copies it has become necessary to Q. 1. Has a device ever as follows: hot water remove all the emul- supply newsstand dealers only with the ac- been perfected and With patented that will obtain power from ocean waves? sion from the film, and dissolve it. Treat the tual number of copies for which they have A. 1. There have been changes the silver orders. This makes it advisable to place hundreds of machines solution with nitric acid, which patented which derive power from the ocean into the form of a nitrate. After gas has stopped an order with your newsdealer, asking him waves. However, none of them to reserve a copy for you every month. have become com- coming off from the solution, treat the remaining mercially practicable, because of the seemingly in- solution until practically all the solid matter is Otherwise he will not be able to supply surmountable obstacles your to their efficient working. dissolved. If you find that some of it does not copy. For your convenience, we are Many of them have been set up and used, but as dissolve, you will know that this is probably not appending herewith a blank which we ask soon as a storm comes up they have been smashed silver. Next prepare a saturated solution of you to be good enough to fill in and hand and washed away. common salt. This is added to the solution ob- to your newsdealer. He will then be in a tained as above, and the result heated to the position to supply copies to you regularly METAL POLISH boiling point. A white insoluble precipitate of every month. If you are interested in silver chloride will be formed, and it should be receiving your copy every month, do not (1659) W. Fauglid, Shelly, Minn., requests: removed by filtering. Add a small quantity of fail to sign this blank. It costs you noth- Q. 1. Can you give me a formula for making ing to so. a good metal polish with which cloths are to dilute sulphuric acid to the silver chloride placed do impregnated be in a glass vessel, and place therein a small and then used on various metals? A. 1. We are giving you below a formula for amount of zinc in any metallic form. Owing to a metal polish: the relations zinc zinc electrolytic of and silver, To Newsdealer Oil of turpentine, 15 parts. chloride will be formed and the silver will he Oil of stearine, 25 parts. precipitated in the form of a grayish spongy Address Jeweler's red or fine rouge, 25 parts. mass. This can be reduced to lump form by melt- A fine quality of animal charcoal, 45 parts. ing it with a blow pipe. Please reserve for me copies of The parts given above are mixed together and SCIENCE & INVENTION every month alcohol is added until the mixture is of the de- VOLUME MEASURED BY DISPLACEMENT until I notify you otherwise, and greatly sired consistency. After the cloths have been (1652) Jesse Reiss, Chicago, Ill., requests: oblige, soaked in this mixture, the alcohol will evaporate, Q. 1. How can the volume of an irregularly leaving the cloth in the desired condition. shaped object which is insoluble in water be de- Name termined? A. 1. If the object is of a small size, and will Address AIR TO DIVERS

not be injured by contact with water, the easiest 1 1 1 1 1 1 1 1 I I i l i m i l 1 1 1 1 . 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 m 1 1 1 1 1 m 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1l l l l (1660) Joseph J. Knapp, Los Angeles, Calif., way to attain the desired results is to measure says: the volume by displacement. Our illustration here- AMBER VARNISH Q. 1. How do divers working below the sur- with shows how this can be accomplished. A in- (1655) John F. Farrell, Boston, Mass., asks: face of the water obtain the necessary air for dicates a graduate filled with water. Note how Q. 1. How can amber varnish be made? I breathing? high the water rises. Now place the object within have succeeded in dissolving amber in linseed oil. A. 1. There are three usual methods for sup- the graduate, the volume of which is to be deter- but when I add the turpentine, the mixture boils plying air to divers. They are illustrated herewith. mined. The water will rise and the amount of over. A shows one of the oldest methods wherein air water displaced will be equal to the volume of the A. 1. We do not have any definite data on the making of amber varnish at hand, but you TO PUMP ESCAPE VALVE could undoubtedly obtain the results you desire OUTLET work. have tA B by experimental Since you succeeded At the right are il- VALVE in dissolving amber in pure linseed oil by heat- lustrated the vari- Small insoluble ob- ing, we would advise you to allow the solution ous methods of jects may be meas- sup« to cool to about 100' Fahrenheit. The turpentine plying air to divers. ured for volume by should then be added stirring constantly until the A-from a pump t h e displacement mixture becomes of the desired consistency. method illustrated on the surface. When heating the linseed oil and amber, you B-from an left. The oxygen BRONZE HELMET OXYGEN at the say that you have trouble with the amber as it tank. degree of rise of C-from a TANK scorches. If the heating were done carefully in tank of OUTLET the water in the chemical ON BACK a vessel contained in a water bath this trouble which supplies graduate indicates the VALVE could very probably be prevented. The heat exhaled air the volume of the with INLET be applied gradually and raised slowly. oxygen. object. should C VALVE 11111111111111111111111111111111111111111111. ,,,iilL,,,,,irourrtrwm111111111lie WATER RHEOSTAT TANK XYLITNE (1656) Geo. M. Brayton, Tela, Honduras, asks: Q. 1. What factors govern the amount of cur- is supplied to the diver through a long reinforced irregular object. This applies only to objects which rent passed by a water rheostat? rubber tube. This tube extends from the diver's will sink. In the case of floating objects, they A. 1. The amount of current passed by a helmet to the boat from which he is working and is must be forced below the surface. The volume of water resistance is determined to a very great attached to an air pump. Air is forced down into the submerged portion of the forcing medium must extent by the density of the solution used. The the helmet under pressure and inhaled by the be considered. area of the electrodes also enters into the calcu- diver. The carbon dioxide escapes through an out- lation as does the distance between them. let valve which is constructed so as not to allow COMPOUND Doubling the distance between the electrodes the entrance of water. VALVE GRINDING would render the resistance twice as great. B shows the oxygen tank method wherein the (1653) William Fisher, Cheyenne, Wyoming, Q. 2. Does the thickness of the sheets used diver carries strapped to his back a tank of com- asks: have any effect on the amperage? pressed oxygen. This is then supplied through a Q. 1. How can a valve grinding compound be A. 2. The thickness of the sheets used as valve to the helmet and the air which has been made? electrodes does not have any appreciable effect on breathed allowed to escape through a valve. A. 1. Ordinary valve grinding compounds of the amperage. At C in the illustration is shown a method uniform grades can be purchased so cheaply that Q. 3. How can the resistance of a water whereby the diver breathes over and over again the it is hardly worth while to attempt to make them. rheostat be calculated? same air which he takes down with him. The air However, if you desire to do some experimenting A. 3. The best way to determine the amount of is renewed by means of a chemical known as with them we would advise you to use a mixture of current passed with any solution is by actual oxylithe which removes the carbon dioxide and flour of emery and heavy cylinder oil. Two or measurement as calculations would fall short or replaces the oxygen which has been used. With three different grades of emery may be used, the would over -reach the mark due to various im- this latter method the diver can stay under water coarsest for starting the work and the finest fer purities introduced into the solution when making for a considerable length of time without any in- putting a polish on the valve and the valve seat. it up. convenience. Science and Invention for April, 1924 1247

''THE AIR IS FULL OF THINGS YOU SHOULDN'T M I S S''

Why Big Cells Count in Radio "B" Batteries THIS handsome metal case Eveready world's foremost electro -chemical "B" Battery No. 766 costs only two- laboratories. We think that No. 766 is the thirds more than the smallest Eveready handsomest battery ever made. But that "B" Battery, but it contains seven times is a matter of opinion. It is a matter of the electricity! This makes the No. 766 engineering record, however, that this over four times as economical as its baby great standard "B" Battery has proved brother. That is why most people buy it. itself as perfect in performance as we are convinced it is superfine in appearance. Its fifteen large cells give 221/ volts of strong, steady energy day after day. The 45 -volt Eveready No. 767 contains Cells that pour out power the moment the same large powerful cells as the No. you turn on your tubes. 766. For maximum "B" Cells that rest well when Battery economy, there- idle, renewing their vigor fore, buy the 221/2 -volt for your next demands. Eveready No. 766 or the 45 -volt Eveready No. 767, No cells have a bluer - blooded ancestry than as you prefer. Here is the "B" Battery at its best. these. They are the prod, Eveready "B" Battery No. 766 2a'di volts. Six Fahnestock Spring Clip NATIONAL CARBON COMPANY, INC. uct of thirty years of dry Terminals, giving variable voltage from for Radio Battery 15'/ to 22'/a volts, in 'h -volt steps. Headquarters Information battery research and Length, 6% in.; width, 4% in.; height, New York San Francisco 3 3/16 in. Weight, 5 lbs. Canadian National Carbon Company, Limited development of the Factory and Offices: Toronto, Ontario

If you have any radio battery problem, write to C. C. Furness. Manager, Radio Division, National Carbon Company, Inc., 209 Manley Street, Long Island City, N. Y. Inform ative and moneysaving booklets on "A, 'B" and "C" Batteries sent free on request.

Eveready 6 -volt Storage Battery Eveready Radio "A" Dry Cell Specially manufactured for use with dry cell Y tubes No. 764 The Space Saver Vertical o Batteries 22Ye-volt "B" Battery -+-they last longer No. 771 No. 767 "C" Battery Clarifies tone and "B" Battery, 45 volts increases "B" Variable taps Battery life Fahnestock Clips 1248 Science and Invention for April, 1924

,,,,,,, ,,, , ,,,,,,, .,,,,,,,,,,,,111,1,,1,,,1,,,111,1,11,,11,,,,,1,,,,,,,,,,1,,,,,,,,,,,,,,,,,1_ adno ¡PonCU cm5t 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.

Power Power Call & Wave Call & Wave Letters Name Location Length Letters Name Location Length KDKA Westinghouse Electric & Mfg. KFEX Augsburg Seminary, Minne- Co., East Pittsburgh, Pa 1000-326 apolis, Minn. 100-261 KDPM Westinghouse Electric & Mfg KFEY Bunker Hill & Sullivan Mining Co., Cleveland, Ohio 500-270 and Concentrating Co., Kel- KDPT Southern Electrical Co., San logg, Idaho 10-360 Diego, Calif. 50-244 KFEZ Amer. Society of Mechanical KDYL Telegram Publishing Co., Salt Engineers (F. H. Schubert), Lake City, Utah 50-360 St. Louis, Mo. 100-360 KDYM Savoy Theatre, San Diego, Cal. 100-280 KFFB Jenkins Furniture Co., Boise, KDYQ Oregon Institute of Technology, Idaho 10-240 Portland, Ore. 100-360 KFFE Eastern Oregon Radio Co., Pen- KDYW Smith Hughes Machinery Co , dleton, Ore. 10-360 Phoenix. Ariz. 20-360 KFFO Dr. E. H. Smith, Hillsboro, KDYX Star Bulletin, Honolulu, Hawaii 100-360 Ore. 5-229 KDZ13 Frank E. Siefert, Bakersfield, KFFQ Marksfieffel Motor Co., Colo- Calif. 100-240 rado Springs, Colo. 100-360 KDZF Automobile Club of Southern KFFR Nevada State Journal (Jim California, l.os Angeles, Calif. 500-278 Kirk), Sparks, Nev. 10-226 KDZI Electric Supply Co., Wenatchee, KFFV Graceland College, Lamoni, Wash. 50-360 Iowa 10-360 KDZQ Nichols Academy of Dancing KFFX McGraw Co., Omaha. Neb 100-278 (Hal G. Nichols). Denver, Colo. 10-360 KFFY Pincus & Murphey, Alexandria, KDZR Bellingham Publishing Co., Bel- L1 100-275 lingham, Wash. 50-261 KFFZ Al G. Barnes Amusement Co , Dallas, Texas ( portable) KFAD McArthur Bros. Mercantile Co , 20-226 Phoenix, Ariz. 100-360 KFGC Louisiana State University, Ba- KFAE State College of Washington, ton Rouge, La. 100-254 , Pullman, `Wash. . 500-330 KFGD Chickasha Radio & Electric Co KFAF Western Radio Corporation, Chickasha, Okla. 200-248 Denver, Colo. 500-360 KFGH Leland Stanford University, (P KFAJ University of Colorado, Boulder, O.) Stanford Univ., Calif 500-360 Colo. 100-360 KFGJ Missouri National Guard. 138th KFAN The Electric Shop, Moscow, Infantry, St. Louis, Mo 250-266 Idaho 50-360 KFGL Arlington Garage, Arlington, Ii FAR Studio Lighting Service Co. (O Ore. 5-234 K. Olsen), Hollywood, Calif 200-280 KFGQ Crary Hardware Co., Boone, KFAU Independent School District of Iowa 10-226 Earn $65 to $200 Boise City, Boise High School, KFGV Heidbreder Radio Supply Co , Boise, Idaho 150-270 Utica, Neb. . 10-224 A Week, Or Go In Business KFAW The Radio Den (W. B. Ash- KFGX First Presbyterian Church, ford). Santa Ana, Calif. 10-280 Orange, Texas - 500-250 For Yourself And Make KFAY Virgin's Radio Service (W. J. KFGZ Emmanuel Missionary College, 50-283 Berrien -Springs, Mich 10-268 Virgin), Medford, Ore College KFBB F. A. Buttrey & Co., Havre, KFHA Western State of Colo- $3,500 to $15,000 Mont 50-360 rado, Gunnison, Colo. 50-252 10-278 KFHB Rialto Theatre (P. L. Beard - A Year KFBC W. K. Azbill, San Diego, Calif. well), Hood River, Ore 5-280 KFBE Reuben H. Horn, San Luis KFHD Utz Radio and Electric Co., St. Yes, 310 months at the Great School of Coyne, Calif. 10-360 located in Chicago, The Electrical Center of the Obispo, Joseph, Mo. 100-226 World, will make you an Electrical Expert capable KFBG First Presbyterian Church, Ta- KFHF Central Christian Church, of commanding big pay. The whole world of elec- coma, Nash. 50-360 Shreveport, La. 150-266 tricity is open to the practical man -the man who has KFBK Kimball -Upson Co., Sacramento, KFHH Ambrose A. McCue, Neah Bay, had actual experience with electrical apparatus. Calif. 100-283 Coyne gives you a practical training on the greatest 10-224 Wash. 50-261 outlay of electrical apparatus of any institution in the KFBL Leese Bros., Everett, Wash KFHJ Fallon & Co., Santa Barbara. World; everything from door belle to power plants. KFBS Trinidad Gas & Electric Supply Calif. 100-360 Co., and Chronicle News, KFHR Star Electric & Radio Co., Seat- Not a Correspondence School Trinidad. Colo. 10-360 tle, Wash. 50-270 N. S We don't make you a mere "paper" electrician. We KFBU The Cathedral (Bishop KFHS Clifford J. Dow, Lihue, Hawaii 30-275 train you by practice on our mammoth outlay of Thomas), Laramie, Wyo 50-283 KFHX Robert W. Nelson, Hutchinson, actual equipment. We train you in house -wiring by KFCB Nielsen Radio Supply Co., Phoe- Kan. 150-229 having you do it exactly as it is done outside - not nix, Ariz. 10-278 just by reading about it. The same applies to armature KFI Earle C. -Anthony, Inc., Los winding, power plant operating, motor installations, KFCF Frank A. Moore, Walla Walla, Angeles, Calif. 500-469 automotive work and hundreds of electrical jobs Wash. 100-360 KFID Ross Arbuckle's Garage, Iola, That's why we can train you to become a M KFCH Electric Service Station, Inc , Expert. Kan. 20-246 Electrical Billings, Mont. 10-360 KFIF Benson Polytechnic Institute, No Lessons Classes KFCM Richmond Radio Shop (Frank Books-No -No T. Doeing), Richmond, Calif. 100-360 Portland. Ore. 100-360 Utah 25-360 KFIL Windisch Electric Farm Equip- KFCP Ralph W. Flygare, Ogden, ment Co., Louisburg, Kan 30-234 You Do Actual Work KFCV Fred Mahaffey, Jr., Houston, KFIO North Central High School, The Coyne practical course includes no books, printed Texas 10-360 Spokane, Wash. 50-252 lessons or useless theory. We train you to work with KFCY Western Union College, Le head and hands on the same kind of electrical KFIQ Yakima Valley Radio Broad- your Mars, Iowa 50-252 Yakima, apparatus as you will find "out in the field". Age, High School, casting Asso., Wash. 50-242 lack of experience or education is no drawback. Our KFCZ Omaha Central KFIU Alaska Elec. Light & Power Co , students range from 16 to 60 years of age. Coyne Omaha, Neb. 100-258 Juneau, Alaska 10-226 gives you Free, a Life Scholarship which enables you KFDA Adler's Music Store, Baker. Ore. 5-360 tt stay as long as you want without extra charge or KFIX Reorganized Church of Jesus return later for more practice and assists you to a KFDD St. Michaels Cathedral, Boise, Christ of Latter Day Saints, position after graduation. Free Radio Course included. Idaho 10-252 Independence, Mo. 250-240 KFDII University of Arizona, Tucson, KFIZ Daily Commonwealth and Oscar Earn while you ! We help students to secure 150-360 jobs to earn a good part of their living Ariz. A. Huelsman, Fond du Lac, expenses while studying. KFDJ Oregon Agricultural College, W is. 100-273 Corvallis, Ore. 50-360 KFJB Marshall Electrical Co., Mar- KFDL Knight -Campbell Music Co , shalltown, Iowa 10-248 Send Coupon Now Denver, Colo. 5-360 KFJC Seattle Post Intelligencer, Seat- Send coupon today for big Free Book and full details KFDO H. Everett Cutting, Bozeman, tle, Wash. 100-270 of our special offer of Free Railroad Fare. Act now! Mont. 50-248 KFJF National Radio Mfg. Co., Okla- ELECTRICAL SCHOOL KFDR Bullock's Hardware & Sporting homa City, Okla. 20-252 COYNE Goods (Robert G. Bullock), KFJI Liberty Theatre (E. E. Marsh), 1300-1310 West Harrison St., Dept. 53-34, Chicago, ID. York, Neb. 10-360 Astoria, Ore. 10-252 KFDV Gilbrech & Stinson, Fayetteville, KFJK Delano Radio & Electric Co , Ark. 200-360 Bristow, Okla. 100-233 KFDX First Baptist Church, Shreve- KFJL Hardsacg Mfg. Co., Ottumwa, port, La. 100-360 Iowa 10-242 KFDY South Dakota State College of KFJM University of North Dakota, Agriculture a n d Mechanic Grand Forks, N. D 100-280 Arts, Brookings, S. D. 100-360 KFJQ Electric Construction Co., Valley COYNE ELECTRICAL SCHOOL, Dept. 53-34 KFDZ Harry O. Iverson, Minneapolis, Radio Division, Grand Forks, 1300-1310 W. Harrison St., Chicago, Ill. Minn. S-231 No. Dak. 5-280 & S Gentlemen: Please send me free your big catalog and KFEC Meier Frank Co., Portland, KFJR Ashley C. Dixon & Son, Stev- a your special offer of free railroad fare. Ore. 50-360 ensville, Mont (near) 5-253 KFEJ Guy Greason, Tacoma, Wash 10-360 KFJV Thomas H. Warren, Dexter, Name KFEL Winner Radio Corp., Denver, Iowa 10-224 Colo. 50-360 KFJW Le Grand Radio Co., Towanda, Address KFEQ J. L. Scroggin, Oak, Neb 150-360 Kan. 10-226 KFER Auto Electric Service Co., Fort KFJX Iowa State Teachers College, Dodge, Iowa 20-231 Cedar Falls, Iowa 50-229 KFEV Felix -Thompson Radio Shop. Casper, Wyo. 250-263 (Continued on page 1250) Science and Invention for Jpril, 1924 1249

óhslá4J i.4dt4/

/ . k

ee cy _ll i` . .Tj ,/J "What's he kicking about now a "

"Same old thing. 'Nother job came back on him and he's grouching about the light again." "Funny he doesn't seem to learn by experience. If he'd use Starrett scales like everybody else in the shop he would n't have any trouble getting accurate measurements - even if the light is poor."

Put a glass over the graduations and you will see at once why Starrett Steel Rules are so much easier to read. Notice how clean cut the figures and division lines are. They are cut deep enough to be plain and distinct even after years of hard service. Starrett Steel Rules make it easier to do accurate work. A rule for every purpose - write for our free Catalog describing the many different Starrett Steel Rules. Straight Edges, etc. Ask for No. 22 "LE"

THE L. S. STARRETT CO. The World's Greatest Toolmakers Manufacturers of Hacksaws Unexcelled ATHOL, MASS.

Starrett STAINLESS Steel Rule No. 1000 6023 Will not RUST OR STAIN. Hardened and Tempered and Invention for April, 1924- I 250 Science

,,,,,,,,,,,,,,,,,,,.111,,,,,,,,,l,,,,11,,,,,,,,,,l,l,,,,l, H,,,,,,,,,,,,,,,,,,,,.,,,,l ® lial°®adcast (Continued from page 1248)

,1 ,,,,.l,n,i.01111111,nileet,rr,llIrl r,,,,,elualliot1111eF1 ,,.,.,..,,..,,,,,,,,,,,,,,,,,,,me,,,,,,,,,1.1,,,,,1,,,1ttolel,,,1,,,llt11,11,1lt,,,,,,,,,,,,,,,,

Power Power Call & Wave Call & Wave Letters Name Location Length Letters Name Location Length KFJY Tunwall Radio Co., Fort Dodge, KNX Electric Lighting Supply Co., Iowa 50-246 Los Angeles, Calif. 100-360 KFJZ Texas National Guard, 112th KOB New Mexico College of Agricul- Cavalry, Fort Worth, Texas. 20-254 ture and Mechanic Arts, State KFKA Colorado State Teachers College, College, N. M. 500-360 Greeley, Colo. 50-248 KOP Detroit Police Dept., Detroit, KFKB Brinkley -Jones Hospital Associa- Mich. 500-286 tion, Milford, Kan 500-286 KPO Hale Bros.. San Francisco, Calif. 500-423 KFKQ Conway Radio Laboratories (Ben KQP Apple City Radio Club, Hood H. Woodruff), Conway, Ark. 150-224 River, Ore. 10-360 KFKV F. F. Gray, Butte, Mont 50-283 KQV Doubleday Hill Electric Co , Pa. 250-360 KFKX Westinghouse Electric & Mfg Pittsburgh, Co., Hastings, Neb. 500-286 KQW Chas. D. Herrold, San Jose, Be An KFKZ Nassour Bros. Radio Co., Colo- Calif. 50-360 rado Springs, Colo 10-234 KRE Berkeley Daily Gazette, Berke- KFLA Abner R. Willson, Butte, Mont. 5-283 ley, Calif. 50-275 KFLB Signal Electric Mfg. Co., Meno- KSD Post Dispatch (Pulitzer Pub minee, Mich. 5-248 Co.), St. Louis, Mo. 500-546 UTO KSS Prest & Dean Radio Co. & Radio KFLD Paul E. Greenlaw, Franklinton, Research Society of Long La. 20-234 Beach, Calif. 20-360 KFLE National Educational Service, KTW First Presbyterian Church, Seat- Denver, Colo. 25-268 tle, Wash. 750-360 EXPERT KFLH Erickson Radio Co., Salt Lake KUO Examiner Printing Co., San II, you're satisfied with $20, $30 or $40 City, Utah 50-261 Francisco, Calif. 150-360 a week, stop reading this right now! KFLP Everette M. Foster, Cedar Rap- KUS City Dye Works & Laundry Co , ids, Iowa 20-240 Los Angeles, Calif. 100-360 It isn't meant for KUY Coast Radio Co., El Monte, II115 KFLQ Bizzell Radio Shop, Little Rock, you. But, if you're BOSS JObsLike Ark. 20-261 Calif. 50-256 after the big money KFLR University of New Mexico, KWG Portable Wireless Telephone N. M. 100-254 Co., Stockton, Calif. 100-360 that goeswith a Albuquerque, KWH Los Angeles Examiner, Los An- real job; listen: KFLU Rio Grande Radio Supply geles, House, San Benito, Tex 20-236 Calif. 500-360 KXD Modesto Herald Publishing Co , We are ready III 100-229 to line you up KFLV A. T. Frykman, Rockford, Modesto, Calif. 5-252 KFLW Missoula Electric Supply Cu , KYQ Electric Shop, Honolulu, Hawaii 20-360 for a big job Missoula, Mont. 10-234 KYW Westinghouse Electric & Mfg. in the Auto- KFLX George R. Clough, Galveston, Co., Chicago, Ill 1000-536 motive Field- Tex. 10-240 KZM Preston D. Allen, Oakland, Calif. 50-360 where (í' KFLY Fargo Radio Supply Co., Fargo, the sky's N. D. 20-231 KZN The Desert News, Salt Lake the limit on op- KFLZ Atlantic Automobile Co., At- City, Utah 500-360 portunity- lantic, Iowa 10-273 KZV Wenatchee Battery & Motor where $75 a week is just a fair starter, KFMB Christian Churches of Little Co., Wenatchee, Wash. 50-360 and where good men pull down $5000 Rock, Little Rock, Ark. 254 WAAB Valdemar Jensen, New Orleans, KFMQ University of Arkansas, Fayette- La. ... 100-268 to $10,000 or more a year. ville, Ark. 100-263 WAAC Tulane University, New Or- KFMR Morningside College, Sioux leans, La. 400-360 City, Iowa 10-261 WAAD Ohio Mechanics Institute, Cin- Get In The Big Money Class KFMS Freimuth Department Store, Du- cinnati, Ohio 25-360 Take your choice of a dozen fine jobs. luth, Minn. 100-275 \VAAF Chicago Daily Drover's Journal, job in- KFMT George W. Young, Minneapolis, Chicago, Ill. 200-286 Work short, easy hours, boss the Minn. 5-231 WAAM I. R. Nelson Co., Newark, stead of being bossed. Be independent-a KFMU Stevens Bros., San Marcos, Tex. 20-240 N. J. 250-263 success! Sound good? Then come on. KFMW M. G. Satereu, Houghton, Mich. 50-266 WAAN University of Missouri, Colum- You can do it! Yes, and do it quickly and KFMX Carleton College, Northfield, bia, Mo. 50-254 Minn. 500-283 WAAW Omaha Grain Exchange, Omaha, surely. It makes no difference whether KFMY Boy Scouts of America, Long Neb. 200-360 you know a carburetor from a.tractor, Beach, Calif. 20-229 WABA Lake Forest College, Lake For- wecan train you,fit you totakeonany KFMZ Roswell Broadcasting Club, Ros- est, Ill. 100-266 well, N. Mex 500-250 WADE Dr. John B. Lawrence, Harris- job-make good and make money! KFNG Wooten's Radio Shop, Coldwater, burg, Pa. 10-266 Miss. 10-254 WABD Parker High School, Dayton Keep Your Old Job- KFNH State Teachers College, Spring- Ohio 10-283 In field, Mo. 20-236 WABE Young Men's Christian Asso- Learn At Home KFNJ Warrensburg Electric Shop, ciation, Washington, D. C 100-283 All the Warrenburg, Mo. 50-234 WABG Arnold Edwards Piano Co , Don't quit your job-stay home! KFO,A Rhodes Company (Dept. Store), Jacksonville, Fla. 10-275 Hold on to your salary while World Seattle, Wash. 500-455 WABH Lake Shore Tire Co., San- you prepare for the big job No Course KFSG Echo Park Evangelistic Associa- dusky, Ohio 20-240 ahead. With our help and tion, Los Angeles, Calif. 500-278 \NABI Bangor Railway & Electric Co , training you can quickly Like This KGO General Electric Co., Oakland, Bangor, Maine .. 50-240 fit yourself for an ex- Investigate! Get Calif. 1000-312 WABK First Baptist Church, Worces- pert's job at top notch the facts on this great KGB Tacoma Daily Ledger, Tacoma, ter, Mass. 10-252 pay, then slip out of course before you de- Wash. 50-252 WABL Connecticut Agricultural Col- the old job into Radio Serv- the new one cide on anything. Learn KGG Hallock & Watson lege, Storrs, Conn. 100-283 why thousands have taken ice, Portland, Ore. 50-360 WABM F. E. Doherty Automotive & without hav- t in preference to any other, Northwestern Radio Mfg. Co Radio Equipment Co., Sagi- ing lost a KGN 100-360 day or a and made good. Portland, Ore. naw, Mich. 100-254 dollar. FREE Auto Book - Tells KGU Marion A. Mulrony, Honolulu, WABN Ott Radio, Inc., LaCrosse, Wis. 250-244 about big salaries, and op- Hawaii 500-360 WABO Lake Ave. Baptist Church, Ro- portunities open to you. Shows KGW Portland Morning Oregonian, chester, N. Y. 10-252 how quickly and easily you can Portland, Ore. 500-492 WABP Robert F. Weinig, Dover, get ready. Send the coupon for KGY St. Martins College, Lacey, Ohio 100-266 your free copy today. Wash. 5 -258 \VABQ Haverford College Radio Club, Automotive Division KIIJ Times Mirror Co., Los Angeles, Haverford, Pa. 50-261 Calif. 500-395 American School 100-360 WABR Scott High School, Toledo, Auto Div. A-426, Drexel Av. & 58th St. KHQ Louis Wasmer, Seattle, Wash Ohio 50-270 CHICAGO, ILL. KJFU Central Power Co., Kearney, \NABS Essex Manufacturing Co., New- Neb. 10-234 ark, N. J 50-244 KJQ C. O. Gould, Stockton, Calif 5-360 WABT Holliday -Hall, Washington, Pa 100-252 Send this "No -Obligation" Coupon KJR Northwest Radio Service, Seat- tle, Wash. WABU Victor Talking Machine Co , Institute of Los Angeles, Camden, N. J. 100-226 Automotive Division, American School, KJS Bible WABV John H. De Witt, Nashville, Los Angeles, Calif. 750-360 20-263 Dept. A-426, Drexel Av. & 58th St., Chicago KLS Warner Bros. Radio Supplies Tenn. Co., Oakland, Calif. 250-360 WABW College of Wooster, Wooster, Send me at once the FREE auto book KLX Tribune Publishing Co., Oak- Ohio 20-234 and all information about your automo- land, Calif. 250-509 WABX Henry B. Joy, Mount Clemens, tive course. This request me KLZ Reynolds Radio Co., Denver, Mich. 150-270 obligates Colo. 500-360 WABY John Magaldi, Jr., Philadelphia, in no way whatever. KMJ San Joaquin Lt. & Power Corp. Pa. 50-242 Fresno, Calif. 50-273 WABZ Coliseum Place Baptist Church, Name. KMO Love Electric Co., Tacoma, New Orleans, La 50-263 Wash. 10-360 WBAA Purdue University, West La- KNT Grays Harbor Radio Co. (Wal- fayette, Ind. 250-360 Address. ter Hemrich), Aberdeen. - WBAD Sterling Electric Co., Minne- Wash. 250-263 apolis, Minn. 100-360 KNV Radio Supply Co., Los Angeles. Calif. 100-256 (Continued from page 1252) Science and Invention for April, 1924 1251

C7Dance in your own home atthe same time, to the same fine orchestra that thrills the exclusive hotel throng

WHEN radio sets are expected to serve the purpose of areal musical instrument, they should be equipped with a Magnavox electro -dynamic Reproducer. Volume of reproduction sufficient for dancing is only one evidence of Magnavox superiority. By means of an electrical modulator the new Magnavox R3 and R2 models can be instantly adjusted to reproduce in anyvolume from very soft to very loud-and current consumption has also been reduced to a minimum. Magnavox Reproducers: Ml (for dry battery sets); R2 and R3 (electro- dynamic) . . $35 to $50 Magnavox Combination Sets: electro- dynamic Reproducer with one or two stages of amplification $59 to $85 Magnavox Power Amplifiers: may be had in one, two or three stage (audio -frequency) $27.50 to $75 Magnavox Products are for sale at good dealers everywhere. Write for catalogue. THE MAGNAVOX CO. Oakland, Calif. New York Office: 370 SEVENTH AVENUE For Every Receiving Set

Perkins Electric Limited : Toronto, Montreal Winnipeg, Canadian Distributors there is a MAGNAVOX 1252 Science and Invention for fl Aril, 1924

,1,{1,,,,,,,,1,,,,,,,,,,,,,,,,,,,,1,,,,1,,,,,,,,,1,,,,,,,,, ,,,,,, , ,,, 11, ,1,,,,,,,11111111111111,,,1 ,. ,1, .11 ,11 1,,11,,,111111,11,111,11110,,111,1111,111,,,,,,,,,1111 1, ,,,, ,,,,,,.11,,,,,,,,,,,,,,,1,111,,,,,,,,,,,11111,11111111,,,,1,,,,M,,,, Your Choice t dio TFroadcaGt (Continuea from page 1250) 75c a Week muumu unnnnnnmm11mummummnmmmmmmmuummmmmmummmmmmunmmnmwuuuummmwuuuunuuuuummmmmumnnmummmmmmnunnnnnnnuamnnummm.uuuunr Power Power Call & Wave Call & Wave Letters Name Location Length Letters Nanie Location Length WBAH The Dayton Co., Minneapolis, WDAP Board of Trade, Chicago, Ill... 500-360 Minn. 500-417 WDAR Lit Bros., Philadelphia, Pa.... 500-395 WBAN Wireless Phone Corporation WDAS Samuel A. Waite, Worcester, Paterson, N. J. 100-244 Mass. WBAO James Millikin University, De- 5-360 WDAU Slocum & Kilburn, New Bed- catur, Ill. 50-360 ford, Mass 100-360 WBAP Wortham-Carter Publishing Co WDAY Radio Equipment Corp., Fargo, (Star -Telegram), Fart Worth, N. D. 50-244 Texas 500-476 \VDBC Kirk Johnson & Co., Lancaster, WBAV Erner & Hopkins Co., Columbus, Pa. 50-258 We have rut Ohio 500-390 WDM The Church of the Covenant. WBAX John H. Stenger, Jr., Wilkes- Washington, D. C 50 -214 the price Barre, Pa. 20-360 \VDZ J. L. Bush, Tuscola, Ill 10-278 WBAY The Western Electric Co., N.Y. 500-492 one-half WBBA Newark Radio Laboratories, \\'EAA Frank D. Fallain, Police Build- Newark, Ohio 20-240 ing, Flint Mich. 10-280 WBBD Barbey Battery Service, Read- WEAF American Telephone & Tele- ing, Pa. 50-234 graph Co., New York, N. Y 500-492 WBBE Alfred R. Marcy, Syracuse, WEAH Wichita Board of Trade, Wich- No matter what your occupation, one of the N. Y. 10-246 ita, Kan. 50-280 home study sets listed below will quickly fit you WBBF Georgia School of Technology, WEAI Cornell University, Ithaca, N.Y. 500-286 for a better job and bigger pay. Any set you select Atlanta, Ga. 500-270 WEAJ University of South Dakota, will lie sent for seven days' examination, and if WBBG Irving Vermilya, Mattapoisett, Vermillion, S. D. 200-283 you decide to buy you may pay the rock -bottom Mass, 100-240 WEAM Borough of North Plainfield price at the rate of only 75c a week. But you must WBBH J. Irving Bell, Port Huron, (W. Gibson Buttfield), North act now! We cannot guarantee these reduced Mich. 50-246 Plainfield, N. J. 100-252 prices for any great length of time. WBBI Indianapolis Radio Club, Indian- WEAN Shepard Co., Providence, R. L 100-273 These books are the work of recognized authori- apolis, Ind. 20-234 WEAO The Ohio State University, Co- ties. They are written in plain, easily understood WBBJ Neel Electric Co., West Patin lumbus, Ohio 500-360 language, by recognized authorities, and contain Beach, Fla. 50-258 WEAP Mobile Radio Co., Mobile, Ala. 100-360 hundreds of photographs, diagrams, tables, etc., WBBK Kaufmann & Baer Co., Pitts- WEAR Baltimore American News Pub- that make difficult points as simple as A -B -C. burgh, l'a. 10-254 lishing full Co., Baltimore, Md 50-360 Handsomely and durably bound in half or WBBL Grace Covenant Church, Rich- WEAS Hecht Co., Washington, D. C. 100-360 Morocco leather (except as noted), and stamped in mond, Va. 10-283 WEAU Davidson Bros. Company, Sioux gold. WBBM Frank Atlass Produce Co , City, Iowa 100-360 Lincoln, 111. 200-226 WEAY Will Horwitz, Jr., Houston, - WBBN A. B. Blake, Wilmington, N. C 10-275 Texas 500-360 Pay Raising Books WBBO Michigan Limestone & Chemical WEB Benwood Co., St. Louis, Mo 500-360 Co., Rogers, Mich 500-250 WEV Hurlburt-Still Electrical Co , At Greatly Reduced Prices WBBP Petoskey High School, Petos- Houston, key, Mich. Texas 50-360 Management, 8 vol., 2500 pages, well illus- 10-246 \VEW St. Louis University, St. Louis, WBBQ Frank Crook, Pawtucket, R. 1 50-252 trated. Was $52.50 Now $29.80 WBBR Peoples Pulpit Association, Mo. 100-261 5 W FAA The Dallas News, The Carpentry and Contracting, volumes, 2138 Rossville, N. Y. Dallas 1000 $37.50. Now 19.80 500-244 Journal, Dallas, Texas pages, pictures. Was W BL T & H Radio Company, An- 500-476 Civil Engineering, 9 volumes, 3900 pages, WFAB Carl F. Woese, Syracuse, N. Y 100-234 thony, Kan. 100-261 \V 3000 pictures. Was $67.50 Now 34.80 W BS D. W. May (Inc.), Newark, FA H. C. Spratley Radio Co , Electrical Engineering, 8 volumes, 3000 N. J. 20-360 Poughkeepsie, N. Y 20-360 pages, 2600 pictures. Was $60.00 Now 29.80 WBT Southern Radio Corp., Char- WFAH Electric Supply Co., Port Ar- Automobile Engineering, 6 volumes, 2600 lotte, N. C. thur, Texas 150-236 21.80 500-360 WFAJ Hi -Grade pages, 2000 pictures. Was $45.00 Now WBZ Westinghouse Electric & Mfg Wireless Instrument Machine Shop Practice, 6 volumes, 2300 Co., Springfield, Mass 1000-337 Co., Ashville, N. C. 50-360 pages, 2500 pictures. Was $45.00 Now 21.80 WCAD St. Lawrence University, Can- WFAM Times Publishing Co., St. Steam and Gas Engineering, 7 volumes, ton, Ohio 250-280 Cloud, Minn. 20-360 WFAN Hutchinson Electric , 3300 pages, 2500 pictures. Was $52.00 WCAE Kaufman & Baer Co., Pitts- Service Co Now 24.80 burgh, Pa. 500-462 Hutchinson, Minn. 100-360 Law and Practice (with reading course), WCAG Clyde R. Randall, New Orleans, WFAQ Missouri Wesleyan College, 12 volumes, 6000 pages, illustrated. Was La. 50-268 Cameron, Mo. 10-360 $97.50 Now 49.80 WCAH Entrekin Electric Co., Colum- WFAT New Colombus College, Sioux Fire Prevention and Insurance, 4 vols., 1500 bus, Ohio 100-286 Fall, S. D .. 50-258 pages, 600 pictures. Was $30.00 Now 14.80 WCAJ Nebraska Wesleyan University, \VFAV University of Nebraska, Dept. Telephony and Telegraphy, 4 volumes, 1728 University Place, Neb .. 500-360 E. E., Lincoln, Nebr 500-275 pages, 2000 pictures. Was $30.00 Now 14.80 WCAK Alfred P. Daniel, Asst. Division \VFI Strawbridge & Clothier, Phila- Sanitation, Heating and Ventilating, 4 vol- Mgr. A. R. R. L., Houston, delphia, Pa. 500-395 umes, 1454 pages, 1400 pictures. Was Texas 50-263 WGAL Lancaster Elec. Supply & Const $30.00 Now 14.80 WCAL St. Olaf College, Northfield, Co., Lancaster, Pa. 10-248 Drawing, 4 volumes, 1578 pages, 1000 pic- Minn. 500-360 WGAN Cecil E. Lloyd, Pensacola, Fla. 50-360 tures, blue -prints, etc. Was $30.00 Now 14.80 WCAM Villanova College, Villanova, \VGAQ Glenwood Radio Corp. (W. G. Employment Management and Safety, 7 vols. Pa. 150-360 Patterson), Shreveport, La 150-360 WGAW 1800 pages, 540 illustrations. Was $52.50 WCAO The Sanders and Stayman Co , Ernest C. Albright, Altoona, Pa. 100-261 Now 24.80 Baltimore, Md. 50-360 WGAZ The South Bend Tribune, WCAP Chesapeake & Potomac Tele- South Bend, Ind. 250-360 phone Co., Washington, D. C. 500-469 WGI American Radio & Research SEND NO MONEY WCAR Alamo Radio Electric Co., San Corp., Medford Hillside, Mass. 500-360 Antonio, Texas 150-360 WGL Thomas F. J. Howlette, Phila- WCAS Wm. Hood Dunwoody Indus- delphia, Pa. 500-360 Shipped for 7 Days' Trial trial Institute, Minneapolis, WGR Federal Telephone and Tele- Yes, we'll gladly ship any set right to your home Minn. 100-246 graph Co., Buffalo, N. Y 500-319 or office upon your simple request. Pay only ship- WCAT South Dakota State School of WGV Interstate Electric Co., New ping charges when the hooks arrive. Don't send a Mines, Rapid City, S. D 100-240 Orleans, La. 100-242 penny until after you have used them seven days, WCAU Durham & Co., Philadelphia, WGY General Electric Co., Schenec- then remit only $2.80 or return them at our ex- Pa, 100-286 tady, N. Y. 1000-380 pense. Pay balance at the rate of $3.00 a month- WCAV J. C. Dice Electric Co., Little \VHA University of Wisconsin, Madi- 75c a week. Rock, Ark. 20-360 son, Wis. 500-360 Act now-while these splendid books are being WCAX University of Vermont, Bur- \VHAA State University 'of Iowa, Iowa offered at 20% to 50% less than regular prices. lington, Vt. 50-360 City, Iowa 100-283 This offer is open to every person within the boun- WCAY Kesselman O'Driscoll Co., Mil- \V HA B Clark W. Thompson, Galves- daries of the U. S. and Canada. Grasp your op- waukee, Wis. 250-261 ton, Texas 200-360 portunity-fill in and mail the coupon NOW! WCAZ Carthage College, Carthage, Ill 50-246 WHAD Marquette University, Milwau- WCBA Charles W. Humbach, Allen- kee, Wis. 100-280 town, Pa. 10-280 W HAG University of Cincinnati, Cin- American Technical Society WCBC University of Michigan, Ann cinnati, Ohio 100-222 DEPT. X425, CHICAGO Arbor, Mich. 200-280 WHAH Hafer Supply Co., Joplin, Mo 250-283 WCBD Wilbur G. Voliva, Zion, Ill 500-345 \V HAK Roberts Hdwe. Co., Clarks- W. Va. r American Technical Society, Dept. X 425, Chicago, U.S.A WCK Stix Baer & Fuller Dry Goods burg, 15-258 Co., St. Louis, Mo 100-360 WHAM University of Rochester (East- Please send me set of WCM University of Texas, Austin, man School of Music), Roch- Texas 500-360 ester, N. Y. 100-283 WCX The Detroit Free Press, De- W HAP Otta & Kuhns, Decatur, Ill 50-360 for 7 DAYS' examination, shipping charges collect. I will examine the books thoroughly and, if satisfied, will troit, Mich. 500-517 WHAR Paramount Radio & Electric send $2.80 within 7 days and $3 each month, until I WDAE Tampa Daily Times, Tampa, Co. (W. H. A. Paulus), At- have paid the special price of 1f I decide not Fla. 250-360 lantic City, N. J 10-231 to keep the books, I will return them at your expense WDAF Kansas City Star, Kansas City, WHAS Courier -Journal and Louisville and owe you nothing. Mo. 500-411 Times, Louisville, Ky 500-400 To insure prompt shipment fill out all lines. WDAG J. Laurance Martin, Amarillo, WHAV Wilmington Electrical Specialty Texas 100-263 Co., Inc., Wilmington, Del 50-360 Name WDAH Trinity Methodist Church \V HAZ Rensselaer Polytechnic Insti- Address (South), El Paso Texas 50-268 tute, Troy, N. Y 500-380 WDAK The Courant, Hartford, Conn 100-261 WHB Sweeney School Co., Kansas Employed by WDAO Automotive Electric Co., Dallas, City, Mo. 500-411 Texas 50-360 (Continued on page 1254) Science and Invention for April, 1924 1253

HaveYou Been Waiting for SIMPLIFIED RADIO? Remember how the bicycle, the automobile, and other popular ! It Has Come inventions were complicated and costly at first? They were simplified and brought within the reach of everybody's pocket- book. SIMPLIFIED RADIO IS HERE!

RADIO PUBLIC RADIO DEALERS

Simple and Easy to One Sells Another Operate The Monodyne tube set is Here is the most practical, guaranteed Radio Receiver the Receiver that is in big you will want. Brings in demand to -day it has local and distant broad- - cast entertainments clear made many radio shops and loud without distor- popular-it will attract tion. The only set made the crowd to your store. in the world with but one tuning control, no dials to Can be used anywhere, in- fuss with. By a simple doors or outdoors. Meets turn of the knob you can tune in or out desired the big call for an inex- stations. No storage bat- pensive, highly satisfac- teries. Thousands of tes- NATIONAL tory set. Easy to handle timonials. A trial will convince the most skepti- and demonstrate. Sells at cal. If your dealer cannot (MONODYNE) list. Quick turnover. Every supply you, fill out the PAT. TRADE MARK PDG. coupon below and mail it one guaranteed. Send for promptly. TUBE SET Sample and Prices. MODEL GT -I National National Monodyne Amplifier Interference Eliminator Want to use a LOUD - SPEAKER? Two Mono Bothered with interference? Get a National In- dyne Amplifiers will operate a loud speaker on terference any Eliminator. Will make any set tune set without howling or distortion. One or sharper-cuts out broadcasting and code interfer- more stages of amplification can be added to ence. Can be used to increase or shorten wave- suit. Without lengths. Tube $8.50 $7.50 Complete Two Inductance Coils

SEND NO MONEY National Airphone Corporation, L 4-24 18 Hudson Street, New York City, N. Y. Gentlemen: Send prepaid the articles National Monodyne. marked, for which 1 will pay - postman upon delivery the National Amplifier. Advertised Price. Interference Eliminator. NAME

STREET

20 HUDSON ST. NEW YORK CITY STATE 12'4 Science and Invention ,for April, 1924 Every Question adHo ibroadcat ANSWERED (Continued froh page 1252) Power Power Call & Wave Call & Wave for only $1 Letters Name Location Length Letters Name Location Length \VHK Radiovox Co. (Warren R. Cox), WMAC Clive B. Meredith, Cazenovia, Cleveland, Ohio 100-360 N. Y. 200-261 At last you have under one cover WHN George Schubel, Loew's State WMAF Round Hills Radio Corp., Dart- Theatre Bldg., New York, N.Y. 100-360 mouth, Mass. 100-500-360 Radio Handbook WIAB Joslyn Automobile Co., Rock- WMAH General Supply Co., Lincoln, ford, III. 50-252 Neb. 100-254 WIAC Galveston Tribune, Galveston, WMAJ Drovers Telegram Co., Kansas JUST OUT Texas 100-360 City, Mo. 250-275 WMAK Norton Laboratories, Lockport, 514 PAGES \VIAD Howard R. Miller, Ocean City, N. Y. 500-360 N. J. 10-254 WMAL Trenton Hardware Co., Tren- Compiled by \VIAF Gustav A. DeCortin, New Or- ton, N. J. 50-256 leans, La. 10-234 WMAN First Baptist Church, Colum- HARRY F. DART, \NIAI Heer Stores Co., Springfield, bus, Ohio 10-286 B.S.E.E. Mo. 20-252 WMAP Utility Battery Service, Easton, Pa. 150-246 \VTAJ Fox - River - Valley Radio Co , Formerly with the WMAQ Chicago Daily News, Chicago, Western Electric Neenah, Wis. 20-224 \VIAK Journal -Stockman Co., Omaha, Ill. 500-448 Co., and U. S. 200-278 WMAV Alabama Polytechnic Inst., Au- Army Instructor Neb. burn, Ala. 500-250 of Radio. Tech- MAO School of Engineering of Mil- WMAW Wahpeton Elec. Co., Wahpeton, nically edited by waukee, Milwaukee, Win 100-360 N. Dak. 50-254 F. H. Doane. WIAQ Chronicle Publishing Co., Mar- WMAY Kingshighway Pre s b y t e ria n ion, Ind. 10-226 Church, St. Louis, Mo 100-280 \VIAR Paducah Evening Sun, Paducah, WMAZ Mercer University, Macon, Ga. 50-268 20,000 SOLD Ky. 100-360 WMC Commercial, Memphis, Tenn 500-500 \MIAS Home Electric Co., Burlington, WMU Doubleday - Hill Electric Co , NO more need you turn from book to Iowa 100-360 Washington, D. C. 50-261 Stores, Boston, Mass. 100-278 book, to find what you want. \VIAU American Trust & Savings WNAC Shepard hoping Bank, Le Mars, Iowa 20-360 WNAD University of Oklahoma, Nor- is all here, in 514 pages crammed full man, Okla. 100-360 It WIK K & L Electric Co., McKees- Neb 20-266 port, Pa. 100-234 WNAL R. J. Rockwell, Omaha, of every possible radio detail. Written WNAN Syracuse Radio Telephone Co , in plain language, by engineers for lay- WIL Continental Electrical Supply Syracuse, N. Y 100-286 Co., Washington, D. C. 10-360 WNAP Wittenberg College, Springfield, men. Clears up the mysteries, tells you WIP Gimbel Bros., Philadelphia, Pa. 500-509 Ohio 100-231 what you want to know. A complete in- WJAD Jackson's Radio Engineering WNAQ Charleston Radio Electric Co , everything within your reach Laboratories, Waco, Texas 150-360 Charleston, S. C. 10-360 dex puts WJAF Muncie Press & Smith Electric WNAR C. C. Rhodes, Butler, Mo 20-231 in a few seconds. Co., Muncie, Ind 10-360 WNAS Texas Radio Corp. & Austin IT EXPLAINS: Electrical terms and WJAG The Norfolk Daily News, Nor- Statesman, Austin, Texas 100-360 circuits, antennas, batteries, genera- folk, Neb. 250-360 WNAT Lennig Bros. Co. (Fred'k Len- tors and motors, electron (vacuum) WJAK Clifford L. White, Greentown, nig), Philadelphia, Pa 250-360 tubes, every receiving hook-up, radio Ind. 30-254 WNAV People's Telephone & Telegraph and audio frequency amplification, \VJAM D. M. Perham, Cedar Rapids, Co., Knoxville, Tenn 500-236 broadcast and commercial transmit- 20-268 WNAW Peninsular Radio Club, Fort Iowa Monroe, Va. 5-360 ters and receivers, super -regeneration, \VJAN Peoria Star, Peoria, Ill . 100-280 codes, license rules. Many other fea- W JAQ Capper Publications, Topeka, WNAX Dakota Radio Apparatus Co., tures. Kan. 100-360 Yankton, S. D. 100-244 WJAR The Outlet Co. (J. Samuels & WNJ The Shotton Radio Mfg. Co Under one cover. Yes, it is all in Bro.), Providence, R. I. 500-360 Inc., Albany, N. Y 55-360 one volume of 514 pages of clear type WJAS Pittsburgh Radio Supply Co., WOAC Maus Radio Co., Lima, Ohio 50-266 Pittsburgh, Pa. 250-360 WOAD Friday Battery & Elec. Co., Sig- with hundreds of diagrams and illustra- \VJAT Kelley-Vawter Jewelry Co., Mar- ourney, Iowa 20-360 tions. Takes the place of eleven or more shall, Mo. 10-360 WOAE Midland College, Fremont, Neb 20-360 \VJAX Union Trust Co., Cleveland, WOAF Tyler Commercial College, Tyler, specialized texts, each costing from two Ohio 500-390 Texas 10-360 to ten times the dollar you pay for this WJAZ Chicago Radio Laboratory, Chi - WOAG Apollo Theatre (Belvidere caso, Ill. 1000-273 Amusement Co.), Belvidere, single book. Belongs in every radio- WJD Denison University, Granville, Ill. 100-273 equipped home, on every amateur's table. Ohio 50-229 WOAH Palmetto Radio Corp., Charles- WJH Wm. P. Boyer Co., Washington, ton, S. C. 100-360 Send $1 to -day and get this 514 -page C. S. D. C. 50-273 WOAI Southern Equipment Co., San Radio Handbook-the biggest value in radio WJX De Forest Radio Telephone & Antonio, Texas 500-385 to -day. Money back if set satisfied. Telegraph Co., New York, WOAL Wm. E. Woods, Webster N. Y. 500-360 Groves, Mo. 500-229 TEAR OUT HERE WJY R. C. A., New York, N. Y 500-405 WOAN Vaughn Conservatory of Music, INTERNATIONAL CORRESPONDENCE SCHOOLS WJZ R. C. A., New York, N. Y 500-455 Lawrenceburg, Tenn. . 150-360 Box 6233-C, Scranton, Penna. WKAA H. F. Paar, Cedar Rapids, WOAD Lyradion Mfg. Co., Mishawaka, Iowa 100-268 Ind. 50-360 I enclose One Dollar. Please send me-post- WKAD Charles Looff (Crescent Park), WOAP Kalamazoo College, Kalamazoo, paid-the 514 -Page I. C. S. Radio Handbook. East Providence, R. I 10-240 Mich. 50-283 is that if I am not entirely It understood WKAF W. S. Radio Supply Co., Wich- WOAR Henry P. Lundskow, Keno- satisfied I may return this book within Eve 50-229 days and you will refund my money. ita Falls, Texas 100-360 sha, Wis. WKAN United Battery Service Co , WOAT Boyd M. Hamp, Wilmington, Montgomery, Ala. 15-226 Del. 50-360 112th Inf. P. N. Name WKAP Dutee W. Flint, Cranston, R. I. 200-360 WOAV 2nd Battalion, ear.. ro.n..nnnnm...mm WKAQ Radio Corp. of Porto Rico, San G., Erie, Pa. 100-242 Juan, Porto Rico 100-360 WOAW Woodmen of the World, Address WKAR Michigan Agriculture College, Omaha, Neb. 500-526 L East Lansing, Mich 500-280 WOAX Franklyn J. Wolff (Monument WKAV Laconia Radio Club, Laconia, Pottery Co.), Trenton, N. J. 500-240 N. H. 50-254 WOC The Palmer School of Chiro- WKAY Brenau College, Gainesville, Ga. 10-280 practic, Davenport, Iowa 500-484 MACHINE Ames, Iowa 100-360 $4.00 ADDING WKY W. K. Y. Radio Shop, Okla- WOI Iowa State College, The GILSON ADDER will ,lo your 100-360 WOK Pine Bluff Co., Pine Bluff, Ark. 500-360 figuring easily, quickly and with abso- homa City, Okla. WOO John Wanamaker, Philadelphia, lute accuracy. It adds, subtracts, mul- WLAG Cutting & Washington Radio Pa. 500-509 tiplies and divides and automatically Corp., Minneapolis, Minn 500-417 Kansas carries from one column to the next. WLAH Samuel Woodworth, Syracuse, WOQ Western Radio Co., Capacity 109,999,999 or $1.099; N. Y. 100-234 City, Mo. 500-360 999.99. Size 31/2"x6"x'". Made WOR L. Bamberger & Co., Newark, with aluminum case and steel operat- WLAJ Waco Electrical Supply Co., N. J. 500-405 ing parts. Written Two -Year Gour Waco, Texas 150-360 muee. Catalogue free. WOS Missouri State Marketing Bur- WLAK Vermont Farm Machine Corp , eau, Jefferson City, Mo 500-441 Price, postpaid. $4.00 Bellows Falls, Vt. 100-360 WPAB Pennsylvania State College, WLAL Naylor Electrical Co. (Sim money back if State College Pa 500-283 your Naylor), Tulsa, Okla 100-360 WPAC Donaldson Radio Co., Okmul- you are not satisfied. W. V. Jordon, Louisville, Ky 15-360 NILES. MICH. WLAP Ree, Okla. 200-360 GILSON SLIDE RULE CO., WLAQ Arthur E. Schilling, Kalama- WPAH Wisconsin Dept. of Markets, zoo, Mich. 20-283 Waupaca, Wis. 500-360 \VLAV Electric Shop, Pensacola, Fla 15-254 WPAJ Doolittle Radio Corp., New MUSIC LESSONS FREE WLAW Police Dept., New York, N. Y. 500-360 Haven, Conn 10-268 WPAK North Dakota Agricultural Col- WLAX Putnam Electric Co., Green- lege. Agricultural College, ó d1 castle, Ind. 10-231 N. D. 50-360 WLB University of Minnesota, Min- 44.1You can read music like this quickly WPAL Avery & Loeb Electric Co , booklet. neapolis, Minn. 5-360 Columbus, Ohio 100-286 IN YOUR HOME. Write today for our FREE Crosley Manufacturing Co., Cin It tells how to learn to play Piano, Organ, Violin.d Mandolin, WLW WPAM Auerbach & Guettel, Topeka, Guitar, Banjo. etc. or op ayers. our cinnati. Ohio 500-309 Kan. 100-360 only expense about 2cc per day for music aand 1postage used. WMAB Radio Supply Co., Oklahoma Okia. 100-360 (Continued on page 1256) AMERICAN SCHOOL of MUSIC, 57 Lakeside Bldg., Chiang City, Science and Invention for April, 1924 1255 "BUILD YOUR OWN" WITH "RASCO" PARTS! Buy from the Oldest and Original Exclusive Radio Parts House in the United States We pay ALL transportation charges in U. S. ALL GOODS SENT PREPAID IN 24 HOURS Order direct Money refunded if from this page. I NOTE NEW PRICES FOR THIS MONTH ONLY I goods do not satisfy

Jacks and Plues Cord Tip Jack P honcho rn Radiocite Detector Audio Frequency Trans- Dun -Cobweb Coil Melotone Loud Speaker Base consists of Phono- Base solid black composi- former For lteinartz circuit, 200- Best popular loud speaker. Best materials. Silver con- Takes place of binding dapter into which fits a tion. Automatic crystal No better Transformer 600 meters. 119 taps. Size Fibre horn, heavy metal tacts. Factory making posta. Cord tip firmly fine enameled fibre born. holder. Triple adjustments. made. Highest class ma- 41" diem.; 11/2" center base, five ft. cord. Nickel Postal Telegraph jacks, gripped by jack. Made of Size of horn 12"; bell Smallest, neatest detector terials. Impregnated coils. opening. Coil is firm and gooseneck. Greatest tuned nickel plated. Screw 61/2". Slip Phonodapter made. Radiocite crystal. Silicon steel stampings will not fall apart. (adjustable) talker. Horn makes these. brass, length A1000 Jack 4 springs 6.65 to attach lead wire. No end on a single telephone 200,000 in use. used. Save 50 per cent by A2650 Cobweb Coil $1.15 111"; bell 8%"; 3 soldering necessary. receiver. A1899 Detector ..$.60 assembling it yourself. A2660 Coil for panel total height 9". A1001 Jack springs .75 met. A255 Melotone Speak - A 1002 Jack 5 springs .80 A 1500 Cord tip jack A132 I Phonelsorn, pre- Galena detec- AI100 Ratio 4V-1 $2.00 mounting. 225-600 A1003 Plug .55 Each $ 15 paid $1.45 tAo 1898 50 AI 150 Ratio 61/2-1 $2.00 $ 1.90 $4.85

75 yACuoM p/yyP+Sl IÌÍ T Ulf Moos OPS _.- reel )50 11.905. £l P_...... ° //\:18 550 naTIC51$ / 59 P9055 FREE Molded Variometer FONEKUSH IONS Straight Line Condenser Radio Frequency Trans- Spaghetti Soldering. Iron Highly substantial instru- Made of sponge rubber. Simplest and most prac- formers Smallest and handiest I FREE( ment. Silk windings. ?á" Make wearing -our5 receiv- tical type of condenser. Varnished flexible cam- iron A4430 "Rico" Condenser Best Radio Frequency bric tubing, 319 takes No. made. Fits any fiat shaft. Flange B when ers a pleasure. Positive- or percolator Plug. Plug The big -Basco" ate- placed into AB direction ly exclude all noises and .001 mfd. 43 plate ca - Transformer developed so 22 wire 320 takes 18 to panel make reception a plleas- 5 far. Designed by R. E. 20 wire 21 takes 16 to then becomes handle. 5" logue. Contains all Arm- makes instrument 123 Lacault. Associate Editor wire 344 takes 22 to with- strong circuits. Every up- mounting. 180 to 650 ure. Sponge rubber will A4230-.00...... 5 mfsl. 18 long, Complete but if for years. Light as plate capacity $1.75 RADIO NEWS. Alr core 28 wire out plug or wire. to-date vacuum tube hook- meters. Money back last 11 type. book this Instrument is not all a feather. A4110 .00025 mfd. 4319-320.321 Perft.S.06 A2200 Soldering up. Greatest little plate $ 1.75 A2800 Transformer, size A344 Flexible soft rubber Free upon receipt that we claim for it. A3550 Fonekushions. set capacity .... printed. 5 50 All types no Rials 81.50 1ys"x21/2" $1.50 tubing; 10 feet for.. 6.20 iron $1.45 of postal. A5350 Variometer $3.00 of two

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hair e39 2055 I9 25- 5615 Knob Litz Wire Copper Ribbon Tin Foil Switch Knob Marconi (Formica Panels Rods thick. Has central hole of 5-32" Clearance Sale Sold in 6" lengths only. .005" and seat to hold screw. threadPrices are per foot. E= A700 %" wide;A701 r/a" All our tin foils come 4" A199 Knob. dia. As we are discontinuing A8032 Rod 8-32" wide; wide. Uniform product 11" dia 11/2", height a/a". sizes, this length . $ 08 equals. A702 3-18" wide. height 8-32" screw. these iaa.rticular A823 E No. 25 B&S 6.02 Ali sizes per foot...5.01 throughout. %"; A838 Knob, each...5.12 material is now offered at A6032 Rod. 6-32 thread has A4451 has 8-32" or Fluted Knob length S 06 A890 ENo. 28 B&S .01 Copper Foil Best grade only A850 cost. All 3-16" thick. wide. inches lb. no screwy With 8-32" bushing. each A1425 Rod, plain 1/2"A891 ENo. 21 B&S .03 .001" thick. 4" 1500 sq. per 10-32" bushing, A352 9x12" $1.75 20 B&S .04 A5025foot Copper FoilSDÌr A851 700sq. inches to lb. Black composition. A354BMx1;9V"ea. 1.90 round, length $. 10 A892 ENo. A199 Knob $ 10 Knob 11/2" Rod, 3-16" 10 per cent discount in A850 Tin foil..lb. $.40 A2055 1" high A356 6x14' each ..1.60 A3616 plain 10 -foot length 80 A851 Tin foil..lb. .40 A445I Knob 06 diain. each $ 15 A357 0:4" each ... .65 round. length $ 06 100 foot lots.

Storage Batteries and Potentio- Rasco Vernier Annie. Bushing Silver Dials Vario- Rotor Rheostats Mounted Crystal -Cup surface black en- Guaranteed for two Made of hand wood. accu- meters Cup has screw and adjust- Why use a vernier conden- Angle piece used to mount Silver years. stand- ser when a vernier attach- panels on board, tubes on amel lettering. For 1/2" Only NEW material used. rately turned. Takes any ment nut. Fits all panels. etc.. 1.000 noes. shaft. No set screw re- Acid proof terminals. Pat- finish. Large hole 2" di- High heat dielectric base. ard mounted crystals. ment will do anything and ent plated, everything a vernier con- 5-16" wide, height 7-16". quired. All 21" dia. vents. ameter. Width 2", diam- Come with tapered, knurl- Nickel polished. A1475 Angle piece. A800 Plate vartometer: A2400 Two volt. 40 eter 3Má". 2 shaft holes. ed knob, 21/4" dia. Com- A3 I B Nickel Cup .. $.20 denser accomplishes? Radiocite Cleverest vernier made. Each $ 03 A801 Prim. Con.; A802 amp. hours 63.90 A343 Rotor S 30 plete with pointer. Seo- Cond. ; A803 Coup- A640 Six volt. 40 Basco" Universal Bear- Best most sensitive mount- Can be used with any A4310 6 ohm . S 45 U. S. Navy dial. Soft rubber rive Adapter Bushing ler' A804 Fil. Rheo.: amp. hours 7.25 ing. Especially made to 30 ohm .65 ed crystal. lit 1/2" A805 Grid Variometer. A666 Six volt. 60 taise above rotor for panel A4311 .... using it. Each tested. engages dial. Nothing to Makes 3-16" dial A4312 Potentiometer. 200 come apart. shaft. Má" long. Each style .....5.20 each MD. hours . 9.50 mounting. A317 Radiocite Crys- Set of six $1.15 Shipped express collect. A1375 Enf. Bearing 5.25 ohms 85 tal $ 25 A1450 Vernier .....5 30 A8866 Bushing , ...5.04

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809 le AERIAL 4 29000, Cord Tips Phone Plugs Bakelite Socket Condensers Name Plates Binding Post Name Plates "Rasco" Posts All name plates brass Dia. styles: from 75c to $1.00 shape. Four nickellBeet make. paper-imereg- e`.--These Made of black crompooi- Standard phone cord tips. Bold Octagon rutted condensers. Capac- with silver letters. Phones. Ground. -, Out- tion. nickeled. everywhere. Hard rubber binding posts. Phosphor A839 (Right or left) 6.10 put, "A" Bat. 'B" 03 shell and pat- springs. ity antd. A809 Comes in 35 styles. Bat. Loud Speaker. A650.51 Each S 08 A315 Each $ composition bronze contact A5050guarPhoneee Condenser. Aerial, -(-, A202 Has nickel-plated Separable Cord Tips ented cord tip holder. Best brown bakelite. Any denomination. 'C" Bat. -, required. Wire 001 $20 sty e5 04 Input, A" Bat. "B" bottom, each .....5.08 No solder Finest workmanship thin - 46510 Bakelite socketS.40 Grid Condenser.$ Panel Scale. 21". 90°. Bat. . -, Loup , Bat. Dozen, each stale...5.90 goes in ferrule. Shank bolds tight, Nickel out. A6500 Tube Socket. Made 0A50560 20 metal, silver background. A122 Initialed Binding it Rasco Telephone A5059 Grid Leak Con- black lettering. A6000 Name Plates all Posts. Six popular styles. plated. A1030 entirely of composition. 10 S 06 . each $ 03 Each $ A2900 Each Plug, each $ 35 Best made. Earls... 5.35 denser, .00025 ....5.30 A715 Scale. Each , 5.15 styles, AUTOPLEX CIRCUIT Aristocrat Post VACUUM TUBES The Binvltag The famous Autoplex circuit de- 1-A4310 6 ohm Rheostat. 6.45 Binding Only the make tubes car- illustrated is Oboe scribed In RADIO NEWS has taken 8-M01 "Fiasco" best latest style has the country by storm. The only Posts .80 ried in stock. All tubes guar- and 8 Binding Post anteed to work. Money re- been enthusiastical- single tube outfit that works a -Assorted ly received. The loud -talker. Results guaranteed. Name Plates . .18 funded or tubes exchanged as illustration 1-A714 Mahogany Cabinet- 5-A6400 Feet Bus Bar Wire .25 long se filament lights. shows 7x14" $3.35 1-A5209 Consolidated Auto - Each full size. Hard Dlex pattern .50 A20 IA 5 volta, .25 amp. $3.75 Rubber Composi- 1 -A71 Panel tion. Fada type 7xiO4Dllectryte 1.20 A199 3 volts, .06 amp. 3.75 2-A5350 Moulded Vario- Total 515.83 (mob, nickel plated 6.00 A 12 1% volts..25 amp 3.75 bottom piece. Brass meters Our special price, screw furnished. 2-A3076 4" Dials .80 $15.25 All above types Amplifiers Introduction price: THE ONE TUBE SET THAT 1-A5014 1250 turn Honey- Complete and Detectors. Posts comb coil .. 1.95 A4022 - BRINGS 'EM IN ON THE Complete with Melo- A200 5 volts, 1 amD...53.35 Each ...... $.07 1-A6500 Vacuum Tube Dozen LOUD -TALKER. Socket .35 tune Loud -speaker D$20.00 Detector type...... 80 A2022 RADIO SPECIALTY CO., 100 Park Place, New York City Factories: Brooklyn, N. Y. Elkridge, Md.

umnummenueppmuntiumntmlutorturnsmemounappelememmellemsomprintmuttmemmor TO RADIO BROADCAST Radio Ama.teur's (Continued from page 1254) -Practical Desin . Cylnilea óyveNBo 5 Pylee.. r MDro Come,., Practical Men 1 t.tll Power Call & Wave Letters Name Location Length and WPAP Theodore D. Phillips, Winches- ter, Ky. 35-360 WPAQ General Sales & Engineering Co., Frostburg, Md. 10-360 WPAT St. Patricks Cathedral, El Paso, Electrical The Consad Co Inc Texas 20-36o o nev ruy,1,1 Y WPAU Concordia College, Moorhead, Minn. 20-36n WPAZ Dr. John R. Koch, Charleston, Students W. Va. 10-273 WPG Nushawg Poultry Farm, New Lebanon, Ohio 50-234 Practical RADIO Yorke Burgess, founder and head of WQAA Horace A. Beale, Jr., Parkes - the burg, Pa. 500-36o famous electrical school bearing his WQAC E. B. Gish, Amarillo, Texas 100-360 name, has prepared a pocket-size note WQAD Whitall Electric Co., Waterbury, Design Data For book for the practical man and those Conn. 50-243 studying electricity. WQAE Moore Radio News Station, It contains draw- Springfield, Vt. 50-275 ings and diagrams of electrical machinery, WQAF Sandusky Register, Sandusky, The AMATEUR over two hundred formulas for calcula- Ohio 5-240 tions, and problems worked out showing WQAH Brock-Amerson Electrical Eng how the formulas Co., Lexington, Ky 10-254 Don't build your Radio Set without KNOW- are used. This data WQAI Coles County Telephone & ING-Howard S. Pyle, U. S. Assistant Radio taken from his personal note book, Telegraph Co., Mattoon, III 10-258 Inspector, and the staff of RADIO NEWS has which was made while on different kinds WQAM Electrical Equipment Co , compiled for the Radio Amateur a complete of work, will be found of value to any- Miami, Fla. 100-283 selection of nineteen clear, concise and accurate WQAN Scranton Times, Scranton, Pa data sheets that are expressly designed to save one engaged in the electrical business. 50-280 TIME, TROUBLE and MONEY. WQAO Calvary Baptist Church, New The drawings of connections for elec- York, N. Y...... 100-360 The tables, information and general data in trical apparatus include Motor Starters WQAQ West Texas Radio Co. (Abilene this compilation are of real reference value for Daily Reporter), Abilene, use when building your set. The and Starting Boxes, Overload - tables give and Under Texas 100-360 methods for the calculation of the Measure- load Release Boxes, Reversible Types, ments WQAS Prince - Walter Co., Lowell, of Inductances, Capacity Wave Lengths. Elevator Controllers, Tank Controllers, Mass. 100-266 Resistance and Capacity of Antennae, etc. Starters for Printing Press Motors, Au- There are also concise diagrams and informa- WQAV Huntington & Guerry (Inc.), tion on several of the most efficient transmitting tomatic Controllers, Variable Field Type, Greenville, S. C 15-258 and receiving circuits used by amateurs. Controllers for Mine Locomotives, Street WQAW Catholic University, Washing- Car Controllers, Connections for revers- ton, D. C. 5-236 ing WQAX Radio Equipment Co., Peoria, CONTENTS OF ENVELOPE Switches, Motor and Dynamo Rules Ill. 100-360 and Rules for Speed Regulation. Also, No. WRAA Rice Institute, Houston, Texas 200-360 1-Measurement of Capacity (Substitution Connections for Induction Motors and \VRAD Taylor Radio Shop, Marion, Method). Starters, Delta and Star Connections and Kan. 10-248 2-Measurement of Inductance of a Coil or Connections for Auto Transformers, and WRAF The Radio Club (Inc.), La- Circuit (Two Methods). porte, Ind. Transformers for Lighting and Power 20-224 3-Measurement of Distributed Capacity of WRAH Stanley N. Read, Providence, an Inductance. Purposes. The drawings also show all R. I. 15-231 Wave- kinds of lighting circuits, including spe- WRAL Northern States Power Co., St 4-Measurement of Fundamental cial controls where Three and Four Way Croix Falls, Wis. 100-248 lengths of Antenna (Three Methods). WRAM Lombard College, Galesburg, III. 250-244 5-Measurement of Wavelength of Distant Switches are used. Transmitting Station Calibration of a Re- WRAN Black Hawk Electrical Co , The Work on Calculations consists of Waterloo, Iowa 10-236 ceiving Set. WRAO St. Louis Radio Service Co , 6-Measurement of Effective Antenna Capac- Simple Electrical Mathematics, Electrical ity. Units, Electrical Connections, Calculating St. Louis, Mo. 10-369 WRAV Antioch College, Yellow Springs, 7-Measurement of Antenna Inductance and Unknown Resistances, Calculation of Cur- Ohio 100-242 Efficiency Capacity. rent in Branches of Parallel Circuits, WRAW Avenue Radio Shop, Reading, S-Measurement of Antenna Resistance. How to Figure Weight of Wire, Wire Pa. 10-238 54-Proper Filtration of the D.C. Plate Sup- Gauge Rules, Ohm's Law, Watt's Law, WRAX Flexons Garage, Gloucester ply. Information regarding Wire used for City, N. J. 100-268 55-Hartley Circuit Employing Full Wave WRAY Radio Sales Corp., Scranton, Self Rectification. Electrical Purposes, Wire Calculations, Pa. 100-280 Wiring Calculations, 56-Navy Standard Regenerative Receiving Illumination Calcu- \VRAZ Radio Shop of Newark (Her- Circuit. lations, man Lubinsky), Newark, N. J. 50-233 Shunt Instruments and How to 57-Five C.W. Transmitter Syn- Calculate Resistance of Shunts, Power WRC Radio Corp. of America, Wash- Watt with ington, D. C. 500-469 chronously Rectified A.C. Plate Supply Calculations, E ffi ci en c y Calculations, WRK Doron Bros. Elec. Co., Hamil- Source. Measuring Unknown Resistances, Dynamo ton, Ohio . 200-360 5S-The Reinartz Tuner. and Dynamo Troubles, Motors and Motor WRL Union College, Schenectady, 59-A 15 Watt C.W. Transmitter. N. Y. 500-360 Troubles, and Calculating Size of Pulleys. WRM University of Illinois, Urbana, 60-A Spark coil I.C.W. Transmitter. Also Alternating Current Calculations Ill. 500-360 61-Wavelengths of Inductance Coils. \VRR City of Dallas Police and Fire 100-Table giving Oscillation Constant and Fre- in finding Impedance, Reactance, Induc- Signal Dept., Dallas, Texas 20-360 quency, for Wavelengths between 200 and tance, Frequency, Alternations, Speed of \VRW Tarrytown Radio Research Lab- 20,000 meters. (L.C. in Microhenries and Alternators and Motors, Number of Poles oratory (Koenig Bros.), Tarry- Microfarads.) in Alternators or Motors, Conductance, town, N. Y. 150-273 101-Table giving Oscillation Constant and Fre- WSAB South East Missouri State quency, for Wavelengths between 200 and Susceptance, Admittance, Angle of Lag Teachers College, Cape Girar- 20,000 meters. (L.C. in Centimeters and and Power Factor, and formulas for use deau, Ms. 100-360 Microfarads. ) WSAC Clemson Agricultural College, with Line Transformers. Clemson College, S. C 500-360 102-Antenna Characteristics. The book, called the `Burgess Blue WSAD J. A. Foster Co., Providence If your dealer cannot supply you, send your R. I. 100-261 order in direct to us with a check, money order Book," is published and sold by us for \VSAG Loren V. Davis and George or stamps. one dollar ($1.00) per copy, postpaid. If Prestman, Sr., St. Petersburg, you wish one of the books, send us your Fla. 10-244 WSAH A. G. Leonard, Jr., Chicago, Ill 500--'-0< COMPLETE RADIO order with a dollar bill, check or money \USAI United States Playing Cards l a DATA order. We know the value of the book Co., Cincinnati. Ohio 500-309 SHEETS and can guarantee its satisfaction to you WSAJ Grove City College, Grove City, Pa. 250-360 by returning your money if you decide \V SAL Franklin Electric Co., Brook- not to keep it after having had it for five ville, Ind. 50-246 50c Prepaid days. \VSAN Allentown Radio Club, Allen- town, Pa. 10--' WSAR Doughty & Welch Elec. Co , The THE McCLURE Fall' River, Mass. . 10-254 WSAT Donohoo-ware Hardware Co , Plainview, Texas 20-268 Consrad Company, Inc. PUBLISHING CO. WSAW John J. Long, Jr., Canadaigua, N. Y. 100-275 Publishers and Sales agents ILLINOIS WSAX Chicago Radio Lab., Chicago, 724 Cass St., CHICAGO, Ill. 20-268 233 Fulton Street, New York City r (Continued on page_1258) Science and Invention for April, 1924 1257

Are YOU One of the 95% Who Suffer from Sick Nerves ? Millions of people are today only half alive and don't know it! They suffer from obscure ills, worry about imaginary troubles, find it hard to concentrate and easily fall a prey to diseases that rob them of their vital powers-all as a result of continuous neglect of their nerves. Bernarr Macfadden, in a wonderful new book which you can obtain free, shows how to recharge your under -nourished nerves and how to acquire glowing health and youthful vitality by following a few easy, natural rules. No medicines, drugs or self -denials, no exhausting exercises or disagreeable diets! DO YOU worry and fuss over out doing anything that isn't pleasant and tions - powerful edi- delightful, you can now recharge your un- torials-exercise arti- A Few of the non -essentials? Do you get food articles- excited easily? Do you blush readi- dernourished nerves and live a full, vibrant cles - Symptoms life that will help you to achieve a glorious health articles-weight of Sick ly? Is your memory weak or your business and social success. c o n t r o 1-personal problems Nerves eyesight failing? Are your hands Based on his many years of experience as health - and feet cold? Are you troubled Macfad- thrilling fiction throb- a physical culture expert, Bernarr bing with life-superb 1. Excitement a n d with constipation or other stomach den has picked out and set down in writing mental depression. rules that have rotogravure section 2. Headaches. dizzi- troubles? Are you pale? Is your certain simple, easy -to -follow showing physically ness. deafness. and women to re- 3. of Is your hair helped thousands of men perfect men a n d Weakness complexion blotched? gain their lost nervous energy and to ac- memory. falling? Have you occasional head- and vitality. women and beautiful- 4. Disturbed sleep - quire glowing health youthful ly developed babies- troubled dreamr. spells? Are you his book, "Strengthening 5. Blprring of sight. aches and dizzy He calls wonderful all glorifying a healthy Weak Nerves." You can obtain a copy 6. Ringing in the troubled with insomnia and too mind in a healthy ears. without extra charge. 7. Feeling of numb- many dreams? Are you impatient body. ness. you Bernarr Macfadden's advice or -emotional, quick to show your joy If follow If you're overweight 8. Cold hands faithfully, you will be overjoyed at the re- f e e t. Flushings or sorrow? You'll look better and feel better you'll find articles on and sweats. sults. how to reduce; if 9. Muscular weak- signs than you did in years; you will have greater ness, lack of en- These are only a very few of the you're too you durance. endurance, a keener appetite and a happier thin that show unhealthy nerves, and if you how to put on 10. Dyspepsia, other life you ever had before. learn stomach troubles. neglect them you will slowly but surely head outlook on than pounds of good, You will banish headaches, worries, con- many 11. Pains around for the same disastrous condition that is now solid muscle. If you're heart misery to thou- stipation. Your complex- 12. Spells of irrita- bringing suffering from consti- bility. sands of people. ion will become clearer, your eyesight stronger, pation, or a poor, sal- 13. Knee jerks. Many a promising and you will gradually low complexion, you'll 14. Strange fears. find even in one single 15. Continuous flow career and many a happy build up a vigorous body of thought pre- home has been ruined by FREE issue wonderful au- venting sleep at that will be able to resist night. New Book thoritative advice that some impulsive word or Amazing nearly every ailment that 1C. Very emotional- bring you renewed Quick to show Joy act. Many a social posi- is at present sapping the will "STRENGTHENING vigor and a radiant or sorrow. tion has been irretriev- energy of thousands. 17. Gloomy - pessi- ably lost by some trifling WEAK NERVES" complexion. mistic, al aYs The book is written in looking on the indiscretion or error of By Bernarr Macfadden dark side of judgment-due entirely to an easy, fascinating style. Special Offer things. is nothing difficult unstable nerves. To think Every reader of Physical Culture can There now obtain the wonderful book with- to understand. You'll en- that one marriage in every out extra charge. Here are some of eleven ends in divorce! its contents: joy every page because it Physical Culture is sold at the newsstands And to think that 95% of What to eat and drink for nerve shows you the wav to glow- at 25c a copy. But for a limited time you energy. ing health and vigor. The all the misery of the un- Causes of fatigue. can obtain a full six months' subscription - happily married is due to How to prevent loss of nerve force. knowledge you'll gain from 6 big issues-in addition to Bernarr Mac- nothing more than irri- How to restore nervous health. reading Bernarr Macfad- fadden's book, "Strengthening Weak Nerves" How internal and external bathing den's book will help you tated nerves. When a man builds healthy nerves. -all for $1.50. loses his temper and flares How to breathe deeply. throughout your entire life, you healthy nerves and vigorous up in excitement; when a Exercises that stimulate weak nerves. for it will build for you a If want The danger of drugs and nerve tonics. solid foundation for your body-if you want to add at least ten years woman begins to nag. How to relax and fret and worry; when a grow strong. future success and happi- to your life and enjoy every minute of it- Special spine child becomes unruly or treatment that ness. then mail the coupon below. The book, soothes the shy-it's simply a case of nervous sys- "Strengthening Weak Nerves," will be sent nerve exhaustion. tem. Mental you at once with the first issue of Physical and emotion- This Splendid Book al influences Culture. Mail the coupon now before this It is a pity that so very that build Sent Free With few people really know healthy remarkable offer is withdrawn. nerves. This Offer how to keep their nerves Ten simple rules f o r Ber - sound and healthful. How strengthen- The advice which much misery could be ing the narr Macfadden has set nervous Macfadden Publications, Inc., avoided, how much unhap- system. down in his wonderful piness could be changed to book, "Strengthening Weak Macfadden Building, Dept. SI 4, joy if the countless num Nerves," is invaluable to 1926 Broadway, New York. bers of people who now every man and woman. I am enclosing $1.50. Please enter my name for a overlook the little signs of nervous exhaus- But if you act quickly you can now special six months' subscription to Physical Culture. This be made see the folly of their entitles me to a free copy of Bernarr Macfadden's book, tion could to obtain a copy absolutely without extra Weak Nerves." neglect. charge. "Strengthening Weak Nerves" "Strengthening is sent free a year's subscription to It is now just as easy to have sound, with magazine is show- healthy nerves as it is to have clean, strong Physical Culture, the that Name teeth and vigorous muscles! Without drugs ing thousands of people the way to glorious or medicines-without tedious, exhausting health. Every month Physical Culture exercises or enforced hateful diets-with- comes to you chock full of copious illustra- Address l25$ Science and Invention for April, 1924

,,,,1,,,,,,,,,,,,,,,,11,1,11111.,,,1,1111111111111111111111111111111111111111111111111,1,1,,,,111,1,,,,,,,1,,,,,,,,,1, ,,,,.,,,, Stain It Any Rada® roa (mot YOU CAN LEARN Color You (Continued front page 1256) NEWSPAPER .11111111111111111111111111111111111111111111/111111,,,111111111111111,,,,111M111111111,,,,1,111111111,113111,,,,,,,,,ll Power Wish Call & Wave WORK Letters Name Location Length WSAY Irving Austin (Port Chester Chamber of Commerce), Port Chester, N. Y. 100-233 Experienced Editor Will Teach You WSAZ Chase Electric Shop, Pomeroy, Ohio 50-258 How to Become a WSB Atlanta Journal, Atlanta, Ga 500-429 Reporter WSL J. & M. Electric Co., Utica, N. Y. 100-273 WSY Alabama Power Co., Birming- ham, Ala. 500-360 FASCINATING WORK --GOOD PAY WTAB Fall River Daily Herald Pub Co., Fall River, Mass. 10-248 WTAC Penn. Traffic Co., Johnstown, Pa. 150-360 Only a Few Months' Work Required WTAF Louis J. Gallo, New Orleans, La. 20-268 To Qualify You for a WTAG Kern Music Co., Providence, Better Position R. I. 10-258 WTAH Carmen Ferro, Belvidere, Ill 10-236 WTAJ The Radio Shop, Portland, Me 10-236 Regular reporters earn from $40 to $125 WTAi, Toledo Radio & Elec. Co., To- ledo, Ohio 10-252 a week. Good deskmen on a daily paper WTAM Willard Storage Battery Co are paid from $60 to $100 a week. A Cleveland, Ohio 1000-390 "Star Reporter can command his own WTAN Orndoff Radio Shop, Mattoon, Ill. 100-240 salary. Hundreds of ambitious men and WTAP Cambridge Radio & Elec. Co , women enhance their income materially by Small odd pieces of modern furni- Cambridge, Ill. 50-242 corresponding for newspapers or writing for WTAQ S. H. Van Gorden & Son, Osseo, ture add greatly to the attractive- Wis. . 100-226 magazines in their spare time. ness and convenience of every home. You, WTAR Reliance Elec. Co., Norfolk, Va. 100-280 WTAS Charles E. Erbstein,. Elgin, Ill. We Will Teach You at Home yourself, can easily make them for your (near) 500-286 family. Finishing of them is a very simple WTAT Edison Electric Illuminating Co We can develop your talent for writing matter if Johnson's Artistic Wood Finishes Boston, Mass. (Portable) 100-244 and lead you into this well paying profes- WTAU Ruegg Battery and Electric Co , sion. Our Practical Course in Journalism are used. Our method involves practically Tecumseh, Neb. 10-360 was personally prepared by Henry J. Brock- no expense. All you need is a little time, a WTAW Agricultural & Mechanical Col- lege, College Station, Texas. 50-280 meyer, Assistant City Editor of the New brush, and WTAX Williams Hardware Co., Streator, York Evening Post. Mr. Brockmeyer has Ill. 50-231 WTAY Iodar-Oak Leaves Broadcasting trained hundreds of men and women, many Station, Oak Park, Ill .. 15-226 of whom have, under his guidance, developed WTAZ Thomas J. McGuire, Lambert- into front rank reporters or feature writers. ville, N. J. 15-283 Mr. Brockmeyer's course will teach you JOHNSON'S WTG Kansas State Agricultural Col- lege, Manhattan, Kansas 1000-485 what it would take years of actual news- WWAB Hoenig, Swern & Co. (John paper work to learn. It consists of six Rasmussen), Trenton, N. J 10-226 comprehensive lessons just brimful of every- WWAC Sanger Bros., Waco, Texas 50-360 WWAD Wright & Wright, Inc., Phil- thing a reporter must learn. The following WOOD DYE adelphia, Pa. 100-360 are only a few of the subjects covered. WWAE Alamo Dance Hall (L. J. Starting in Journalism. What is a News- Johnson's Wood Dye is very easy to Crowley), Joliet, Ill 500-227 WWAF Galvin Radio Supply Co., Cam- paper? What is News? Start and Finish apply-it goes on easily and quickly, den, N. J. 100-236 of a News Story. Technical Terms. The a lap or a streak. It penetrates WWAO Michigan College of Mines, Type Point System. Styles of Type, Proof without Houghton, Mich. .... 250-244 deeply bringing out the beauty of the grain WWI Ford Motor Co., Dearborn, Reading. Capitalization and Punctuation. without raising it-dries in 4 hours and does Mich. 50-273 A Late Fire Bulletin. Court Stories. Libel WWJ Detroit News (Evening News), Laws, not rub off or smudge. Made in fourteen Copyright. Hints to Reporters, Per- Detroit, Mich. 500-517 sonal Conduct. Re -Writing and Condensing beautiful shades. WWL Loyola University, New Orleans, La. 100-280 Stories. Paragraphs and Short Items. Good and Bad Styles. Broadening the Vocabu- Book on F. lary. Aids to Good Style. Special Stories. FREE -This Suggestions for Stories. Rhetoric. Prepar- The Resuma ffn ing Your Story. Don'ts for Writers. Office Home Beautifying AprUli Organization. Syndicated Matter. Business Office. Mechanical Department. Hints for This Book tells how to finish wood By ISABEL M. LEWIS, M.A. Headline Writers. The Make -Up. The Country Correspondent, etc., etc. in artistic stained and enameled (Continued fron pacte 1224) effects. Gives practical suggestions on mak- Use 50% ?0.11111.,,,,,l,,,,l 11111,,,iemmummunnI,,,,,,,,,,,,,,,,,,,,,,,,,e,,, Coupon-Save ing your home artistic, cheery and inviting. Although the price for the entire course is Tells just what materials to use and how to constellation of Ursa Major, the Greater $10, entitling the student to full consulting apply them. Includes color card-gives cov- Bear, and by the inconspicuous groups of services directed by Mr. Brockmeyer per- ering capacities, etc. Use coupon below. Lynx and Camelopardus. After being hid- sonally, we will accept enrollments, if the den from view for the greater part of the coupon below is used before May 20, at $5- winter by trees, houses or other obstructions exactly half price. that cut off our view of an object when it lies close to the horizon, the Big Dipper is Five Days' Trial now swinging around to a high position Just pin a check, money order or five dollar above the pole and will be seen to the best bill to the coupon below and mail. Then advantage from now on through the spring take five days after the course arrives to and summer. In speaking of the Big Dipper decide whether you want to keep it. If not, it is well to bear in mind that it is hut a return it at our expense and your money part of the constellation of Ursa Major. To will be immediately refunded. west and south of the Dipper are a the THE PRESS GUILD, N. number of stars of the third and fourth Inc., 66-S West Broadway, Y. magnitude that belong to the constellation r S. C. JOHNSON & SON, Dept. SI 4. of Major. In fact they mark the head THE PRESS GUILD, Inc. (Expires May 20. 1924) Wis. (Canadian Factory-Brantford) Ursa Racine, and forepaws of the bear. The seven stars 66-S-West Broadway, New York City. Please send me free and postpaid your Instruc- Enclosed find and Wood Finishing. $5 for which you are to ship me at tion Book on Home Beautifying of the Dipper mark the back and the ridicu- once, prepaid, Henry J. Brockmeyer's complete course in Practical The beat dealer In paints here is: lously long tail of the creature who differs Journalism with the distinct understanding that If I return the course In five days my full $5 will in this respect from all others of his kind, be refunded and no questions asked. except the Lesser Bear of similar MY NAME unless we (Name) form which lies near by with the tip of the MY ADDRESS ..-(Address) tail marked by the pole -star, Polaris. - CITY & STATE 1260) ra (Continued on page (City) (State) dn

Science and Invention for April, 1924 1259

Noted Musical and Radio Authorities Select three Distinctly New Radio Song and Dance Hits ...:.... .

The fro- _.y_ .. Cindm, AfAiaY lyric1- .. JackArun'-.

.z:p f,v:.F:':RY"' .\Yfi,..,,,? zS'1 AL..ic,2 : , mS ,. ° ...... :... :". drr.?6w?k.,... .:.

Now We Have Radio Song and Dance Hits

In a recent nation-wide Musical Radio Contest three com- lek x0 !vC'r+Z).V,1GA"1!NE positions were selected from the hundreds of Manuscripts 35c BROADCAST CONTI=="! li. ;'.;;..á. submitted as prize winners. These numbers have now EACH been published in the conventional form so that Radio Postpaid Music Lovers and also Music Lovers everywhere can enjoy these distinctly new hits in Popular Music. These prize Radio Hits will be a sensation in your dance folio. They offer you the opportunity of buying three fine melodies at the same time each better than the other. It were as if you had picked the choice numbers out of hundreds of songs at your dealer. These Radio Song and Dance hits will be exclusively Radio-To and for the Radio Public. They will be Broadcast from your local Broadcasting station. Listen in for them. Your local Radio Dealer will have copies for you. Look them over the next time you visit him or write us direct for your copies. Published and Distributed by THE CONSRAD COMPANY, INC. 233 Fulton Street, New York City

Radio Jazz: Listen In: Radio March: Irresistible foxtrot One of Featured in RADIO NEWS Another Prize Winner , of the prize winners of RADIO Broadcast contest, has caught RADIO NEWS Broadcast con- Its test. Here, music lovers, is a NEWS Broadcast contest! the fancy of all America! wonderful number! Is there Young feet dance-old feet tap rare swing hypnotizes-and its anything so appealing as the time, to the fascinating melody tuneful melody makes it simply stirring strains of a military of this real smashing hit. irresistible. march? 1260 Science and Invention for April, 1924

,,,,,,,,,,,,,1111,,,e,,,111,,:,,1,1,,,,1,,,11111,1,,,1,,,,,,,,,,,, 111,,,,11,11,1,,,1,,,11,,,,,,,,1,,, The Heavens we Teach Il If2l Agp i Hl COMMERCIAL book (Continued fruit page 1258) 1111ea,1,,,,,,,,,,aa,,,,,,,,,,1,,,11, 1,1,1,11,11,1,,,,,,,,,,,,,,,,,,,,,,,,,,, 1, 1, 1,,,,,,,,,,,,,,,e The North American Indians, we are told, also saw in this constellation a bear, but the ART three stars of the tail were to them the Meyer Both Company, the largest hunter and his dogs. Although this con- Commercial Art Organizationinthe Here! stellation seems to have been known uni- World offers you an unusual opportunity for versally in all ages and all lands as The Bear, practical training, based upon twenty-three years it has also been known, particularly in Eng- of success. This nationally known organization land, as The Wain, and frequently as The each year produces and sells to advertisers over Plow, the three stars in the handle of the 15,000 commercial drawings. Meyer Both in. Dipper representing in this case the Plow - struction is the difference between successful fact Oxen. Among the Romans it and experimental theory This well paid profession equally was often re- open to men and women. Home study instruction. ferred to as The Seven Plow -Oxen. In early England it was Arthur's Wain and Cet Facts Before You Enroll in Any School later Charles' and, usually The Ask the Advertising Manager of the leading neFs- Wain today, papers in your city, anywhere in the United Wain or The Plow. States, Canada, England or Australia about A DOUBLE STAR the Meyer Both Company-let them tell you about us. Write for our illustrated book The middle star in the handle of the telling about the success of our students-for dipper, Mizar, and its nearby Alcor, a star one-half the cost of mailing-four cents in stamps of the fourth magnitude, is a well-known MEYER BOTH COMPANY naked eye double star that is popularly DeparZment of Art Instruction Iwill make known as the horse and his rider. In Ger- Michigan Ave. at 11th St., DepL64 CHICAGO, ILL. many Alcor is Hans, the wagoner, and in Note-To Art and Engraving Firms: Secure practical artists among our graduates. England, Jack on the middle horse. Any- Write us. you a one with fairly good eyesight should have no difficulty in making out this fairly bright Be in the ad- companion of Mizar. To the Arabs the vance line ANew DRAFTING ability to separate the two stars was a test of discovery of eyesight. You can work new wonders in Close to the meridian at this time and a voice modulation Photo - little to the southeast of the zenith is Leo, and carry on ad- EXPERT! vance experiments If you're earning less than $100 a week, GO INTO one of the most conspicuous of the spring in radio with the DRAFTING! I guarantee to train you AT HOME groups. It can he easily recognized by its Cummings long - Electric the "JOB-WAY"-with actual Drafting Room jobs. hied stable characteristic Sickle. The star at the end Photo - Electric Send for my free book, find out about the wonder- Cell. You c a n ful opportunities to earn big money in this easy, of the handle is the first -magnitude star enter the field fascinating business. Drafting experts are close Regulus, or as it has been of telephotography L1 Cell to the boss-are first in line of promotion for popularly called, a n d television. executive positions. Cor Leonis. It is one of the white, hydro- Diagram of con- N lag nections fur - S gen stars and its distance from the earth is nished with or - tier. Sent $200 to $400 a Month! about fifty light years: Some distance to the prepaid cast of Regulus is RESEARCH Common schooling all you need! I train you by the second -magnitude star GENERAL LABORATORIES my copyrighted "JOB -WAY" instruction. I cover Denebola, which marks the tip of the lion's 326 River Street, Chicago every branch of Drafting by giving you actual tail. This star makes with Arcturus, the JOBS to do. No books or useless theory to waste your time. My graduates are SUCCESSFUL- orange -hued giant star now visible in the LEARN WATCHWORK, JEWELRY WORK enrployers PREFER Coyne -trained Draftsmen. northeast, and with the beautiful white star AND ENGRAVING So I guarantee satis- Spica in Virgo, in the southeast, a huge equi- A fine trade commanding a good salary and faction or to refund your services always in demand or you can every penny of your lateral triangle the appearance of which may start in business for yourself. At money! be taken as announcing the. arrival of spring. BRADLEY INSTITUTE THE PLANETS VISIBLE The greatest school for watchmakers In the world. FREE Dra; Outfts 4klreas Horological Department S.T., Bradley Poi> - "JOB -WAY" trahi- The planet Venus is now setting about technic Institute, Peoria, Illinois, for our latest cuts - ing makes you a legue. It's free for the asking. DRAFTING EXPERT nine P. M. the first of the month and is a quick because you most beautiful and conspicuous object in the learn to do actual JOBS with the same western sky in the early evening hours. It instruments you will use when employed at reaches its greatest eastern elongation on the A sturdy, dependable motor car. Any handy man a big salary. To en- its or boy can build it. Power supp'ied by famous 23-5 tourage you to START twenty-second of April, when angular H. P. SHAW Motor. RIGHT NOW, I will Send for illustrated Clr- distance from the sun is a little over forty- lae 2 eta. postpaid. give you with my Complete Illustrated course this complete five degrees. It will be in the constellation Book of Building EXPERT'S outfit Plane 25e Postpaid. FREE. Coupon brings of Taurus throughout the month and its Write today.ar. rolnplet rr information. SHAW MeD EB. position is indicated on the chart for the Dept. 12 LEARN AT $ first, middle and last of the month. It is Galesburg,Kas still increasing in brightness and will not HOME reach its greatest brilliancy until the latter Thousands of big - part of May. salaried lobs all over the country looking for Mercury will reach its greatest elongation DRAFTING EXPERTS! Rail- east of the sun on the sixteenth of April. Begin Today-Write for My FREE HOOK.. I roads, factories, builders, archi- can make a good penman of you at home daring tects, ship yards, auto plants, It will then be about twenty degrees east of pare time. Write for my FREE BOOK, "How Cities, Counties, States and the To Become a Good Penman. It contains epeel- the sun and should be visible in the north- a d tells how others mastered penman - It. S. Government all calling for by the Tambirn System. Y o osame will Drafting Experte, all waiting for west for a short time immediately after sun- bhipe elegantly written on a caed if you a los. you to take the big pay lob. stamp to pay postage. Write today for book. Mail coupon, get my free book. set as a bright star of the first magnitude. F.W.TAMBLYN, 424 Ridpaldg,K City, U.S.A. Let nie tell you the, rest of this Mars is in constellation of Sagittarius e ory personally. Address the the first of the month and passes into Capri - cC Broadcasting from Atlantic Coast, t Mexico, Canada, Cuba anti Hawaii, CHIEF DRAFTSMAN cornus before the end of April. It is still 2650 Miles ON TUBE heard in California by SCHOOL OF visible in the east in the early morning hours ONE CROSS COUNTRY CIRCUIT. COYNE DRAFTING -Atlantic Coast users hear California. Range due to and on the thirteenth of the month is on simplicity of set and operation by only one tuning Dept. 436. 1-9 S. Ashland Ave., Chicago control. Easy and cheap to build by any novice. Dry the meridian at sunrise. cell tubes may be used. Complete understandable in- Jupiter is in the constellation of Scorpio structions, full size panel layout, assembly photo, etc. Postpaid, CHIEF DRAFTSMAN a little to the east of Antares. It now rises 25e.; Stamps accepted. COYNE SCHOOL OF DRAFTING before midnight but is not visible at the time VESCO RADIO SHOP Dept. 436, 1.9 S. Ashland Ave., Chicago. Box S. I. il? OAKLAND, CALIF. Without obligating me in any way please send me your for which the chart is given. abso- hoot, Drafting, the Foundation of Industry," is now in Virgo a few. degrees WHY NOT IMPROVE YOUR lutely free. Also complete information of your rapid home - Saturn study Drafting course, Free instruments and special offer, east of Spica. Its position is given on the PERSONAL APPEARANCE? Send for booklet showing photos of Men chart for April fifteenth. On the nineteenth with and without the (PERFECT LEG Name FORMS) for BOW LEGS and KNOCK it will be in opposition to the sun. It will KNEES. Also BRACES, for children for St. No. then rise at sunset and be on the meridian PERMANENT CURE. Perfect Salsa Co.. 140 N. Mayfield Ave., City State at midnight. Dept. 50 Chicago. III. Science and Invention for April, 1924 1261

_,,,,,,.,,t,nn,,,,l,o,,,,uml,,,,,I,,,,,,1,,,,,,,,,,,,,,,,,,,,,,,,,,,.111.11,,,,,,m,,,,,m1,,,,,,.1,,,,1,1111a ,,._ Mt.;tor lsHHllAS Valve grinding, adjustments, troubles The sure way to big- and cures BY TOM C. PLUMRIDGE ger pay is through Automotive Expert ; , rn,olnnunn1111111111111111111errmeree.mulroolotrIlorlummelruu11ununnnnmwwunununun1n1uunic the Croft books THE Croft Library is the last word in practical electricity. It is complete, up-to-date, Stem, Vise and above all, authoritative. You can rely upon every line and every illustration being right. Valve Croft shows you how to master the finer points of electrical practice. He teaches you electricity as experts know it and puts you in line for an expert's pay.

Move cloth back and forth The Croft Library of over stem Practical Electricity NO COURSE, no set of books, offers a quicker, surer Emery cloth -A- method of mastering electricity than the Croft Library. It is founded on practice-on work as it is actually done. It is jammed from cover to cover with the kind of hard-headed, pay -raising facts you want. The automobile engine must have good compression to have Written so that the beginner can easily understand it, power, and to get good compression the valves must have a yet so sound, so thorough that it is the daily guide of good seat. The exhaust valves are the first to give trouble, thousands of highly paid electrical workers and engineers. because they are subject to the heat of the hot gases, and Iq the Croft books you will find complete, detailed and they are the ones that need most grinding. The stems up-to-the-minute information on electricity, from the sim- should be polished first. Emery cloth is the best thing to plest principles, to complete and economical operation of use and the method for polishing them is shown ire Sketch A. a central station-motors, generators, armatures, commu- tators, transformers, circuits, currents, switch -boards, distribution systems-electrical machinery of every type, installation, operation and repair-wiring for light and power-how to do it mechanically perfect, in accordance with the National Electrical Code-wiring of finished buildings-Underwriters' and municipal requirements- how to do the complete job, from estimating it, to com- pletion-illumination in its every phase-the latest and most improved methods of lighting-lamps and lighting effects. Thomas A. Edison, the electrical genius, said: "Croft's method of explaning by analogy with things everyone knows, and the simple illustrations make his work one of the best I have seen." It would take you many, many years and cost you thousands of dollars to gather together the information, the diagrams, the results of experiment and experience that are available between the covers of these eight handy volumes-all summarized, illustrated and brought up to date, printed clearly and thoroughly indexed. Own a set and join the 40,000 men who have found the Croft Library to be a real working companion to bigger accomplishment in the electrical field. Keep these books handy in your room. Put one in your pocket when you take the car or train in the morning. Give them The next operation is to clean out the guides. Use a good the odd hours. They are not tiresome treatises, but as tool for this as shown above. Split a thin rod down the interesting as any reading matter you ever owned. Con- center and wind a piece of emery cloth around it; but sult your set regularly, acquire just one new fact a day, first insert the cloth in the slit so that it will not slip. and in a few years you will be a broadly informed elec- Place the tool in the guide and work it back and forth trical man. until all of the carbon is removed from the guide; after this is completed the valve is ready for grinding. Free Examination Small Monthly Payments We want you to test our statements-we want you to compare the Croft books with others. Fill in and mail the coupon attached and we will send you the entire set of eight volumes for ten days' Free Examination. We take all the risk-pay all charges. You assume no obligation-you pay nothing unless you decide to keep the books. Then $1.50 in ten days and the balance at the rate of $2 a month. Send the coupon NOW and see the books for yourself. Our new price and our new terms make it possible for anyone to own a set of Croft. Send no money-just the coupon!

FREE EXAMINATION COUPON

McGRAW-HILL BOOK CO., INC., 370 Seventh Ave., New York. Gentlemen:-Please send me the CROFT LIBRARY OF PRACTICAL ELECTRICITY (shipping charges prepaid), for 10 days' free examination. If satisfactory, I will send $1.50 in ten days and $2 per month until $19.50 has been paid. If not wanted, I will write you for return shipping instructions. Before grinding place a light spring under the valve so t at when the pressure is released the valve will be raised off Name the seat and the grinding compound will be allowed to et Home Address under the seat. Plane a little of the grinding compo nd on the face of the valve and put it in place. Press ligh ly City and State on the screwdriver and rotate the valve back and for h. Company or Employer Occasionally release the pressure, as already stated. Ske ch Will in all lines) C will show how this is done. When the valve and s at show a continuous ring around them the valve is ground in. Occupation Wash valves and guides thoroughly with gasoline before ti B. I-189 assembling. M 1262 Science and Invention for April, 1924 Personal 1 Stationery

I [l l Valve above valve seat Valve below 200 SHEETS and 100 CORRECT POSITION valve seat INCORRECT POSITION -D- -E- ENVELOPES Printed

A valve in its correct position will stand a little above with your Name and What's holding the seat as shown in sketch D but excessive grinding will often bring the valve below the top of the seat as shown Address you down ? at E. THERE is only one thing in the world that's holding you down. It isn't that "the boss doesn't like you," or that "you 11 ..nu,,.to,,,11, never had a chance," or that "the other fellow has all the luck." $1.00 CUTTER No-it is none of these. It is lack of Little wider than End view training. Down deep in your heart you valve seat of' cutter Clear, white bond paper, know that the reason the other fellow is getting ahead is because he's doing things that with envelopes to match. you cannot do. Why don't you study some one thing and get Your name and address ready for a real job, at a salary that will give your wife and children the things you would like Pilot to fit- printed in beautiful, rich them to have? - volve guide You can do it! Pick the you position want in ROTATE IN RIGHT blue ink, on both paper the work you like best, and the I. C. S. will pre- HAND DIRECTION and pare you for it right in your own home, in your - F- spare time. i envelopes, and sent to you Yes, you can do it! More than 180,000 men are doing it right now. Join them without an- postpaid for only $1.00. this is the case then the top of the seat must be If other day's delay, and get in line for promotion. r cessed until the valve again stands above the seat. A t of for this is shown in sketch F. When making this inconvenient to send the Mail the Coupon To -day! ool he sure that the pilot fits the valve guide snugly. money, we will ship C.O.D. INTERNATIONAL CORRESPONDENCE SCHOOLS Box 6232-C, Scranton, Penna. Without cost or obligation on my part. please tell me tJ, how I can qualify for the position or in the subject before which I have marked an X: BUSINESS TRAINING COURSES Write name and address Business Management Salesmanship Industrial Management Advertising Personnel Organization Better Lettere Traffic Management Show Card Lettering plainly. ['Business Law Stenography and Typing Banking and Banking Law Business English Accountancy (including C.P.A.) D Civil Service Nicholson Coat Accounting Railway Stall Clerk Bookkeeping D Common School Subjects q Private Secretary High School Subjects Elite Stationery Spanish French Illustrating Company TECHNICAL AND INDUSTRIAL COURSES Electrical Engineering Architect Electric Lighting Blue Print Reading 5030 Main Street Mechanical Engineer Contractor and Builder Mechanical Draftsman ['Architectural Draftsman ['Machine Shop Practice Concrete Builder Railroad Positions Structural Engineer Smethport, Pa. Gas Engine Operating Chemistry O Pharmacy Civil Engineer Automobile Work Surveying and Mappingg [Airplane Engines eand ini Agriculture and Poultry °MtalSteam Engineering Radio Mathematics

Name A valve that is loose in the guide, or one whose face is CARTRIDGE PISTOL Street CLANKProteetron Burrgher,, Trumpa, & Dog. Address not true with the seat will allow the valve to touch on one aeainae PRICES side of the seat first and then drop over on to the other City State side; this causes a clicking noise which is hard to locate. 55c0c: Sketch G shows this condition. Occupation Persona residing in Canada should send this coupon to the International Correspondence Schools Canadian, Limited, POST- Montreal, Canada PAID Weil Tana and Of. estive; modellee$ on latest type of Bevolverw- appearance alerte ,.1,11111111111411111111111111111 ero emes . Sell TIRES ibmgr evaosvffectiWve a DIRECT FROM FACTORY ow telife. I takes dud- We want one auto ownerin each locality ant , Cal. artndr obtainable - to use and adyertiee Armour Corde. You P n CO SIM bìorquality $1.00 post. can make big money and gQetyonr own tires Pree Blank Cartriá[e., by express. S0c 100. by simply sending us orders from friends and JOHNSON SMITHS, co. Dept. 105 Racine. Wla. No Capital or Experience needed. neighbors. daily. We deliver and collect direct. Pay you MODEL SLIDE VALVE MARINE Moo tLibera 'Tire Guarantee Ever Written ENGINE- Armour Cords are Bonded against Accidental l/:" bore, $ 12.75. or s/e" bore, S15.75 Damage, Wear and Tear, Tread Separation, Blis- You will probably wish to make your tering, Blow -Outs and Rim-Cutting for own model boat hull, but what about 10,000 miles. We are actual manufactur- your power unit? We are builders of ers. Write today for Great Special Offer working model engines and boilers of and low Factory Prices. many types. We can supply you with a to Agents Some angle) power unit that will meet the require- ARMOUR TIRE 8 RUBBER CO.,Dep154cDAYTON.O. Pilot--- ments of your particular model boat. as valve seat Boller, Ship and Naval fittings. Special work. Large illustrated catalogue, 20e. BATHE MEG. CO. NO -H- Dept. 2, 5214 Woodland Ave.. Phila.. Pa. MORET spend Spring, Summer TAMMER WHY NOT and Fall gathering but- SKill the fear of stammering. Re-education the terflies, insects? I buy hundreds of kinds for key. The widely famed Hatfield Method fully be collections. Some worth $1 to $7 ea. Simple outlined In an accurate, dependable worth. There is another reason wily valve guides should a good lined need outdoor work with my instructions, pictures, while book-"HOW TO STOP STAMMERING." a fit. Sometimes the seat will become badly and price -list. Send 10c. (not stamps) for my Il- has inºpired thoueendº. Free COPY today. truing up, and for this purpose a valve re -seating tool lustrated Prospectus before sending butter- THE HATFIELD INSTITUTE, 109 N. Dearborn, Chicago, III. should be used. Sketch H. flies. Mr. Sinclair. Dealer in Insects, Dept. 33, Ocean Pk., Calif. Science and Invention for April, 1924 1263'

Valve stem..., .006" to .015' No Matter What Your Vocation valve ,clearance

Valve tappet Lock nut- adjustment e screw

Valve push rod --er&\ 'I

1 Valve push rod guide Professional Man Af er the valves are replaced they must be adjusted for Whether cl arance, that is, space allowed between the push rod and Man or Daily Worker valve stem to allow for expansion, so that the valve will Business close when hot. A feeler gauge should be used for this purpose. Sketch I. First rotate the crankshaft until the piston is on top of the compression stroke, and then set the tappet or push rod until a feeler gauge of .006 A Thorough Training In inch will pass between the stem and tappet. To find the top of compression stroke, watch the intake valve open and close and then bring the piston to the top of that stroke. If a piece of wire is inserted in the spark plug hole the piston can be felt when it comes to the top. CHEMISTRY Valve stem Will Help You To Get Ahead play _Valve guide TO be successful today is to know Chemis- SLOANE try! Every line of business, every DR. T. O'CONOR Felt branch of industry depends upon Chem- Will Teach You Chemistry Valve istry in sonic form. You may not realize it, but your own proficiency in whatever work you are In Your Own Home spring doing would be increased by a knowledge of The Chemical Institute of New York. of which Dr. Chemistry. In many lines such knowledge is T. O'Conor Sloane is Educational Director. was founded Light spring absolutely essential. In others it is a guaran- to fill the need of ambitious, far-sighted men who tee of promotion and more money. realize and recognize the splendid future Chemistry of- -J-. fers them, but who cannot apare either the time or the a foremost au- keen exists in every money to attend college. Dr. Sloane. The competition that thority on Chemistry, will teach you and will give you commercial activity today requires that a man any individual help you may require. He will person- Valve collor -Valve stem know all there is to know about his vocation. ally go over your papers, correct them, point out your If you have something to sell-no matter what faults, teaching you in a practical and interesting way. -Chemistry enters into its makeup. The sales- No special education required other than the ADDY to read and write English. One student has ehar- man who knows the chemical composition of his takes mys- Ai leaks at the intake valves will cause an engine to run than acterized our lessons as "The course that the method is how to article can talk about it more intelligently tery out of Chemistry." poorly and at low speed. A shown lacks this information, and his stop this sketch J. Place a piece of felt at the bottom the one who in sales are proportionately larger. In the build- One Our Recent the with a spring to hold it in place. Where Read What of of guide is prime importance. guide and stem are worn it is best to ing trades Chemistry of both valve and mason, electrician or who knows Graduates Reports where the cannot be taken out over The painter replace them, or guide something about can do better work "I thought I would let you know of my succoso. I valve stems should he fitted. Chemistry months ago and now have size and command more money than the one who finished your course about two a fine position as chemist at the DuPont Dye Works. does not. Through Chemistry a shop -keeper I am getting along fine with my work and like it very learns how to attract the most trade, and even much. It was through your course alone that I have in clerical positions one can capitalize his been so successful. It is wonderful and I hope you have great success with it." Tire ThoIl Handle Uses chemical skill. (Name and Address on request.) should be as much a part of your TIR1_. Chemistry TOOL \VIiIi MODIFICATION 15 mental equipment as the ability to calculate or Easy Monthly Payments USEFUL AS A JACK HANDLE to write correct English. The world is paying You do not have to have even the small price of the a thpusandfold more for ideas than for actual course to start. You can pay for ft in small monthly labof. The big rewards go to the man who can payments-so small that you won't feel them. The cost Is very moderate, and includes everything, even the show how to turn out a little better product Laboratory Equipment-there are no extras to buy with at a little lower cost. And Chemistry will give onr course. Our plan of monthly payments places a you the ideas that will save money for your- chemical education within the reach of everyone. self or your firm in the very fundamentals of your business. There is nothing remarkable Laboratory Equipment Given about this; it is going on every day. If you LENGTHS OF'WRou0HT have not heard of it before, it is because the To Every Student Without IRON PIPE ARE DRIVEN general public has been slow to recognize the Charge tremendous value of chemical training. People Additional OVER, ENDS OF TIRE. We give to every student without additional charge have been content to leave Chemistry in the his chemical equipment, including forty-two pieces of IRONS hands of a few trained chemists who could not laboratory apparatus and supplies, and seventeen dif- possibly develop the subject to anywhere near ferent chemicals and reagents. These comprise the its greatest extent. apparatus and chemicals used for the experimental work of the course. Now we are on the eve of a great awakening. Our heritage from the World War has been an intense de- Special 30 -Day Offer velopment of the chemical industries in the United For a short period we are making a special offer States and a tremendous interest in all the applica- that will be worth your while to take advantage of. tions of Chemistry. People are taking up the subject Write for particulars, using the coupon below or merely for the good it will de them in their ewn line simply a postal card. This will not obligate you in of business. the least. Do not wait until tomorrow. Send the now while you think of it. It is no longer necessary to enter college in order to coupon learn this fascinating science. Our Home Study Course trains you just as thoroughly, and with the same Sign and Mail the Coupon for assurance of success, as those who took the longer way. And our methods are so simple that we can teach you BOOK no matter how little previous education you may have FREE had. Many of our graduates now hold responsible posi- 7 tions or have materially increased their incomes from r private enterprises as a result of taking our course. CHEMICAL INSTITUTE OF NEW YORK, Ins. Hundreds of letters from studente testifying to the Extension Division 4. benefits they have derived from our training are here Home for your inspection. 66-S West Broadway, New York City. any obligation Remember that you do not need to study Chemistry Please send me at once without as a chemist. al- on my part, your Free Book "Opportunities for with the idea of actually practicing about the Labor- though a great many of our students are taking our Chemists," and full particulars want to know atory Equipment furnished to every student. Also course with this object in view. If you of payment and more about what Chemistry will do for you, if you want please tell me about your plan to know what our home study course offers, sign and your special 30 day offer. mail the coupon today for FREE BOOB, "Opportunities for Chemists." IMPROVEMENT OF EX- NAME TENSION HANDLES ADDS Chemical Institute TO COMFORrAND of New York, Inc. ADDRESS HOME EXTENSION DIVISION 4 CITY- A length of wrought iron pipe forced over a tire tool as a handle will increase the use of the tool to a great extent. 66-S West Broadway, New York City STATE Here are shown several uses to which such an improved S.&L,4-S4 accessory may be applied. -G. A. Luers. 6mua- 1264 Science and Invention for April, 1924

RAD H O Your Radio Set W1KHHKLE5 needs SOLDER : LL EDITED BY a real metal solder American Machinists' Library A. P. PECK, in paste form Associate Member Institute Radio Engrs. Ready for this heading we are going to UNDERpublish items of interest to everyone instant who likes to build radio instruments. In use order to continue this department it is necessary for our readers to tell us about their latest experiments. Write us a short description of some time- or money -saving kink you have discovered and send it to us THE day of the trained machinist is here! along with a few sketches. Our regular On every hand employers are calling for prizes will be paid for this material. Be brief and try to put everything in the him-bidding for him! They are looking drawing. Don't be too elaborate. Address for men really know machine "RADIO WRINKLES" editor, care of Solders All Joints who shop practice- Science and Invention. men who are capable of handling all kinds of INSURES CLEAR RECEPTION 11 1111 111 1 111 1 1 1 1 1 1 1 1 1 1 1 1 1 111 1 111 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 1 , 1, 11,t111,11111 111 1111/111 111111 1111 1 1 1 1 1 1 1 1 1 1 1 1 11111 machine shop work equally well. On Sale al' All Dealers The that is in all-round knowledge demand today VACUUM TUBE UNITS The SOLDERALL CO. is the kind of knowledge you get in the new Ameri- NEWARK,N.J. can Machinists' Library. 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Oaklnd 8...24m1. data on every phase of machine shop work. The set Hupp StdbkrLt8 .23mL Bodge 28m4 Overl'd4...32m4 Cole 8 ..... 17ml. should be in the hands of every man who wants to If your car is not mentioned bere send name and model foe make himself a master of modern machine shop particulars and our guarantee on it, AGENTS WANTED SENT ON 30 DAY'S FREE TRIAL practice. You can drive any car in heaviest traffic wit out shifting grate. Starts off on high in any weather without priming or heating- no jerking or choking. No more foul spark plugs or carbon Machine shop work in cylinders. No leaking of gas into crank case. Try it 30 American days on our guarantee of money back if not entirely eatisfied. as experts know it No strings to our guarantee. YOU ARE THE JUDGE. Machinists' Anyone who can handle a wrench can attach it. No boring of Within these six volumes new holes or changing of onerattng mechanism. Write today. 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On one of the units, Vol. 3-Punches a n d teresting text and illustra- binding posts should be left for a grid leak and condenser Dies. tions. so that this unit may he used for the detector. The others Learn the Simplex Way! Vol. 4-1 igs and Fix- need not have this, as they will usually be used as am- tures. With these books a man Let us prepare you at home to become Vol. 5-Tool and Gage can know machine shop plifiers. If desired, audio frequency amplifying trans- Work. practice as experts know formers may be mounted permanently in one or two of an auto Expert. Vol. 6-Work i n g of these units so that they may be used when desired. Steel. it and fit himself to earn an expert's pay. -Leroy Western, Reporter No. 15. Write for SPECIAL OFFER Free Examination-Only $1.00 in DOUBLE BINDING POSTS SIMPLEX AUTO SCHOOL 2016-2024 W. Van Buren St. 10 Days and $2.00 a Month for 7 Months Fill in the coupon below and we will send you a set UPPER POST ACTS of these books for 10 days' Free Examination. No men h are In de- obligation. We pay carrying charges AS SET SCREW mand.For morethan a quar- expense-no Electrical ter of a century this school has both ways. If you find the books to be what you been training men of ambition and limited time for the TO LOWER ONE electrical industries. Condensed course in Electrical want send us $1.00 in ten days and the balance in t grad- monthly installments of $2.00 until the special price e uates to se- Engineering cure good of $15.00 has been paid. positions and promotions. Theoretical and Practical Elec- tricity. Mathematics. Steam clod Gas Engines and Mechan- ical Drawing. Students construct dynamos, install wiring and test electrical machinery. Course with diploma FREE EXAMINATION COUPON STUD SOLDERED complete TO POST In One Year Over 3000 men trained. Thoroughly equipped fireproof dormitories, dining McGRAW-HILL BOOK CO., Inc., aéra hall, laboratories, shops. Free es Wog. 31st year begins Sept. 26, 1023 370 Seventh Avenue, New York. BLISS ELECTRICAL SCHOOL lof TAI[OMA AVE., WASHINGTON, D. C. Semi me for -ten days free examination your American Machinists' Library, all charges prepaid. If satisfactory, I will send,$1.00 in 10 days and $2.00 a month until I have paid your special price of $15.00 for the set. If they are not what I want I will write for return shipping instructions. %l%/ SOLUTELYFREE Signature Thousands of

'tes. Address ' ADIO BARGAINS Double binding posts can quickly be made from two single City and State You Can't Equal This Anywhere posts by cutting off the head of the thumb screw of one SRACO head sets -2.000 bands and cord and soldering the stud to the base of the other one. The Big Ohms-head Your Employer Make complete. Write Dept C for two posts are then assembled as shown above. con- $2.98 nections to the bottom one first and then to the top one. Catalog catalog. Your Occupation -F. E. D. FRIE STANDARD RADIO CORP. 5. 1. d - "- 1 (Will the author kindly forward his full name and address? Ed.) 227 WEST MADISON ST. CHICAGO Science and Invention for April, 1924 1265 LIGHTNING ARRESTER

MICA D15K oó 0ó FIOLES

ir .- B BASS LEAD INj _TRAP

CARBON A DISK F_OD5 Aviation Brings Quick Success 3RA55 TO S ETI ST RAD Fascinating-Daring--Big Paying To young men of dar- after one reading, the ing no field NON- INFLAMMABLE BASE other of PREPARE student gets a thorough work offers such a fas- understanding. One cination, such high pay, NOW FOR THE never tires of reading A simple yet efficient lightning arrester may easily be nor such opportunities FUTURE them." James Powers, made from two carbons taken from dry cells, a mica disk, and two strips of brass. lio'es are drilled through the for quick success as the Pa., another student, mica disk at intervals as shown at the top of the above Aeronautical Instructor field of Aviation. As yet, : illustration. The disk is then placed between the ends $60 to $150 per week says "I am indeed sur- of the copper rods which are fastened to a non -inflam- is Aeronautical Engineer aviation practically in $100 to week prised that such a valu- mable base by means of the two brass strips and four $300 per screws. The carbons should touch the mica disk on each its infancy. NOW is the Aeronautical Contractor able course can he had Enormous profits side. The connections to this arrester should be made in time to prepare_ from such practical the same manner as any standard type and it is preferable Aeroplane Repairman men $60 to $75 per week to use it in connection with a lightning switch. The wire for so little cost." marked "lead-in," should also go to the set, while that Amazing Opportunities Aeroplane Mechanician $40 to $60 per week marked "to set," should go to the ground. in the Airplane -Roy Dooley. Aeroplane Inspector Personal Instruction Industry $50 to $75 per week Aeroplane Salesman by Experienced In the automobile in- $5000 per year and up Men HONEYCOMB CONTROL Aeroplane Assembler dustry and in the moving $40 to $65 per week Men who have h a d Aeroplane Builder picture business hun- $75 to $200 per week actual experience g i v e dreds of men got rich by you personal attention. getting in at the start. They select the lessons, DIAL PANEL They made their success before lectures, blueprints and bulletins. others woke up. Today, these lines They tell you things that are essen- offer no greater opportunities than tial in everyday practice. Each les- 4""ROD a hundred and one others. BUT son is easy to read and under- SMALL BRASS THREADED GUIDE ROD AVIATION IS NEW. Get in stand. DOWEL while there is an opportunity. All = over the country there will be a Get Big FREE Book Now clamor for trained men. It will not Send coupon below for N e w be a question of pay but of getting Book, just out, "Opportunities in capable men. the Airplane Industry." It is in- / (HONEYCOMB WOODBLOCK 1 col Ls THREADED teresting and instructive. It will A Sure and Easy Method show you many things you never of Becoming knew before about aviation. Due an Aviation Expert to shortage of paper we could get $50 to $150 per Week only a limited supply of these books -send the coupon before they are The study of is CABINET ,%4" PLO D aviation almost all gone. as fascinating as the actual work. Every lesson is full of interest. American School of Aviation That is why it is easy to learn Dept. 7454 f one has access to a wood turning lathe on which threads can be cut, a very good honeycomb coil mounting aviation. You do not have to make 3601 Michigan Avenue Chicago, Ill. and regulating device can be made. First, a wooden block is obtained which will just fit within a honeycomb coil yourself study-it is like reading P and a hole is cut in the center and threaded. A dowel an interesting book tells you is then threaded with the same size thread. The wooden that AMERICAN SCHOOL OF AVIATION with block the large hole in the center is then glued things you have always wanted to 3601 Michigan Ave., Dept. 7454. Chicago, Ill. within one of the honeycomb coils and a small hole drilled through it for the guide rod. It is advisable to glue an- know. Only one hour each evening Without any obligation, send me your Free Book. other wooden block within the other honeycomb coil which "Opportunities in the Airplane Industry" also in- will give you the basic training in formation about your Course in Practical Aero- in turn is mounted on the cabinet. The entire assembly nautics. is made as shown above and a dial is fastened to the end a surprisingly short time. of the rod. By turning the dial, the threaded dowel will Name revolve, causing the movable honeycomb coil to move One student, S. F. McNaughton, closer to or further away from the stationary coil, depend- Chicago, says: "Your lessons are ing upon the direction in which the dial is turned. Street -F. R. Donahue. like a romance, and what is more, (Continued on page 1270) City Mate 1266 Science and Invention for April, 1924 U.S. PAT NTS

SEND'SF FOR ; ,;'I I ND F OM E áted by Don't Lose Your Rights Before disclosing your invention to any- Joseph H. Kraus one trend for blank form "Evidence of as to be signed and witnessed. Conception" is of A sample form together with printed in- In this Department we publish such matter as interest to inventors and particularly to those structions will show you just how to work who are in doubt as to certain Patent Phases. Regular inquiries addressed to "Patent Advice" cannot establish your be answered by mail free of charge. Such inquiries are published here for the benefit of all readers. If up your evidence and rights the idea is thought to be of importance, we make it a rule not to divulge all details, in order to protect before filing application for patent. As the inventor as far as it is possible to do so. attorneys we represent registered patent charge of $1.00 is over U. S. Should advice be desired by mail a nominal made for each question. Sketches hundreds of inventors all the and descriptions must explicit. Only one side of sheet should written on. and Canada in the advancement of inven- be clear and be tions. Our schedule of fees will be found NOTE:-Before mailing your letter to this department, see to it that your name and address are upon the letter and envelope as well. Many letters are returned to us because either the name of the inquirer reasonable. The form "Evidence of Con- or his address is ception" sample, instructions relating to incorrectly given. obtaining of patent and schedule of fees sent upon request. Ask for them,-a post ELECTRICAL SWITCH good financial backing. Consequently we would card will do. advise against applying for patent. Bear in (787) Carlos Bonilla, Gandia, Spain, has de- mind that we do not desire to condemn the signed a multiple blade switch which will control idea, but like most inventions of this class, this a number of circuits because of an ingenious blade device would present no possibility of a return motion of the switch. for the original investment. A. Instead of your switch being of particular 255 OURAY BLDG., value, it is a hindrance in ordinary electrical circuits. Only in a very few circuits could this BLOTTING ATTACHMENT FOR FOUNTAIN WASHINGTON, D. C. switch be employed. You will note that at any "Originators of form Evidence of Conception" time, only one of the four circuits could be in PENS operation. With several switches any of them (791) R. W. Wensko, Lakewood, Ohio, has could be thrown in. In addition to that your de- designed a blotter for fountain pens in which a vice is not rigid enough to be continually prac- small roller made of blotting paper is placed at tical. the end of the cap of a pen. This is to be replaced We would not suggest your applying for a when saturated with ink. patent on this device. A. Although at first glance your idea of a small blotting attachment at the end of a fountain LOCK NUT pen may have appeared to be a very practical sug- (788) Thomas George White, Seattle, Wash., gestion to yourself, you will note that the roller at has designed a rather complicated lock -nut and the end of this pen would be very small indeed. bolt combination. Being of such a diminutive size, the roller would TO THE MAN A. Do you think any one would purchase your become clogged with ink in a very short time. It WITH lock -nut arrangement considering cost of its manu- is very difficult also to turn this pen over and roll AN IDEA facture? It is a very simple matter to drill two it along the writing. The rollers as described by or three holes through a bolt and pass a cotter key you will also be quite expensive, costing much I offer a comprehensive, ex- through it. With a nut this forms a lock -nut more than a group of blotters. perienced, efficient service for that is quite efficient. Assuming even that your W e frankly believe that this device holds no his prompt, legal protection device is superior to the one just mentioned, do commercial value whatever, and would not suggest and you realize what it means to cut a longitudinal applying for a patent. the development of his proposi- groove into each individual bolt to construct the tion. nut as shown? The nut you show is a special type. SPRING BRACKETS Send sketch, or model and descrip- To construct a key to fit the slot and to tap out MOLDING tion, for advice as to cost, search the end of the bolt for the reception of a screw ROLLER IN through prior United States patents, which is to hold the key in place would incur PLACE etc. Preliminary advice gladly fur- another enormous expense. Would you, as a nished without charge. manufacturer, undertake the construction of a My experience and familiarity with device of this nature, when you know that a device various arts. frequently enable me to which will perform the same duty can be con- accurately advise clients as to prob- structed in three complete operations? TOP' VIEW able patentability before they go to The ordinary bolt and nut with an ordinary lock an expense. washer may be employed effectively to perform ooklet of valuable information the work of your complicated invention and cost iºuWgr and form for properly disclosing much less. your idea, free on request. Write We most emphatically advise against apply- today. ing for a patent on this idea because you will WOODEN CORE RICHARD find that you cannot effect a sale, try as hard B. OWEN, Patent Lawyer as you will. 164 Owen Building, Washington, D. C. 2276-8 Woolworth Bldg., New York City ELECTRIC DOOR ALARM (789) Leslie White, Montrose, Colo., has de- REMOVABLE ROLL signed an attachment to be fitted into an ordin- W ITt-1 $LOTTI N 4 ary door lock converting it into an electric alarm PAPER sounding device without destroying its effec- CAN BE C. L. PARKER tiveness as a lock. REN EWE )a Ex U. S. Patent A. The device you have originated is very -Member Examining Corps, Office elaborate in comparison with other devices serv- seen at- Attorney -at -Law and ing a similar purpose. The writer has A blotting roller for a fountain pen is impractical on tachments which could be built for 10c, and Solicitor of Patents could be marketed for less than $1.00, which will account of its diminutive size. American and Foreign Patents secured. Searches made do the same work as your system and may be to determine patentability, validity and infringement. installed with much less trouble. We would Pamphlet of Instructions sent upon request. surely not advise you to apply for a patent on the ANNULLING GRAVITY McGILL BUILDING WASHINGTON, D. C. system you have advanced, as it is, in reality, (792) B. J. I. Cahigh, Oakland, Calif., asks not an attachement but a new lock. The process if any one has ever built a machine which will of drilling holes through the metal casing of a annul gravity. lock after removing it from the door, placing A. There have been several attempts made to the contact springs in place, aligning them and build small machines to annul gravity. One of drilling holes through the door for the wire and these in which high frequency currents actually derive larg- inserting insulating bushings is entirely too com- suspended small silver balls was described in this est profits know journal. No attempt has been made to build whoand heed certain plicated. This is not the kind of work to which INVENTORS simple but vital the ordinary housewife is suited and your sys- a large machine. We frankly believe that such facto before applying for Patents. Our book Patent -Sense tem should be developed for her, not for the a device is possible, but the cost of building it gives those facts; sent free. Write LACEY & LACEY, locks together with the cost of experiments bringing Established 1869. electrician. The latter can install of this 644 F St., Washington, D.C. nature and has them always on hand. it to practicality would be prohibitive. The anti - gravitation railway, designed by Mr. Emile Bache - let, uses alternating currents to produce similar DEMOUNTABLE TIRE RIM action. If you will make your letter a little (790) W. G. Walsh, Canso, Nova Scotia, more explanatory, we will be glad to give you requests our advice on a demountable rim for further advice upon this subject. automobiles. A. It is quite possible that your invention VARIO -COUPLER WITH DEAD END PATENTS is patentable, but we doubt very much if it BOOKLET FREE HIGHEST REFERENCES would be worth while to patent it. Present day SWITCH PROMPTNESS ASSURED BEST RESULTS demountable rims are practically standardized. F. Fox, Redondo Beach, Calif., re- model (793) Send drawing or for examination In view of the fact that your rim does not - report as to quests our advice on a vario -coupler with a fan and patentability shbw any marked improvement over other rims, switch thereon, the purpose of which is to elimi- WATSON E. COLEMAN, Patent Lawyer we fail to see why the present rim should be nate dead end losses. 644 G Street, N.W., Washington, D. C. supplanted. A demountable rim is a very hard object to place upon the market unless you have (Continued on page 1268) Science and Invention for flpril, 1924 1267 r ! IT ln .,_ - . EXPE,1,`

[(,_ - A VFr .7 ' '1 J-_i J-tr...r.J-2-F- T3ic---r S717:stT.Ìt7`w.

r'\J h igk PAIMINJT AkTr r014Alg E REGISTERED IN UNITED STATES PATENT OFFICE MEMBER OF THE BAR OF SUPREME COURT OF UNITED STATES, COURT OF APPEALS DISTRICT OF COLUMBIA, SUPREME COURT DISTRICT OF COLUMBIA. UNITED STATES COURT OF CLAIMS. PRACTICE CONFINED TO PATENTS AND TRADE MARKS.

PROTECT YOUR IDEAS ANY NEW article, machine, design or improvement thereof, or any new combination of parts or improvements in any known article which increases its efficiency or usefulness, may be patented, if it involves invention.

Tha¡Hny and Specification Roonz of Clarence A. O'Brien, Registered Patent Attorney, Washington. D. C. IF YOU HAVE ANY NEW IDEAS No Charge for This Information which you feel are useful, practical and novel, take prompt action to protect your rights. If you have AU communications are held in strict confidence. My invented any new machine, or new combination of personal, careful and thorough attention is given to parts of improvement. or any new design or process, each case. I offer you efficient, reliable and prompt SEND DRAWING, MODEL OR DESCRIPTION of service-based upon practical experience. Highest it for information as to procedure to secure protection. references. Write Today for Blank Form WRITE TODAY for free book "How to Obtain a Patent." This book will give you valuable informa- "Record of Invention" tion, and it may save you much time and effort. USE THE COUPON attached, and immediately Send for it, NOW. upon its receipt I shall send you this form to be My practice is devoted exclusively to United States returned to me with drawing, description or model and Foreign Patents and Trade Marks. Write me of your idea; promptly upon receiving your idea I freely, frankly and with full confidence; it is very v shall write you fully as to procedure and costs. probable that I can help you. Write TODAY.

CLARENCE A. O'BRIEN, Registered Patent Attorney. WASHINGTON. D. C. 531 Security Savings & Coral Bk. Bldg., directly across street from U. S. Pat. Office Please send me your free booklet, "How to Obtain a Patent" and blank form FREE "Record of Invention" without any obligation on my part. Pam; COUPON Address (IMPORTANT: WRITE OR PRINT NAME CLEARLY) 1268 Science and Invention for April, 1924

En 1111111n1,,,,,,n,nen,nm mr11.11111111111,n,1.,,,,,,.,,n,,,,,,,,,,Imn,.loll,,,,n,,,,,,,nmne ;.;;.=,z:;;=}°. F,> Patent Advice (Continued frone Lage 1266) CAN YOU think of a simple, practical idea A. Your idea of a vario -coupler does not that will fill one of the many represent any radical departures from or any valu- quests we have on file for new in- able advantage over other vario -couplers found ventions? It may mean a fortune for upon the market, except that there are no dead- you. Thousands of things are needed end losses in the same. Nevertheless, vario -couplers Right Now. Your brains can help. today have but relatively few turns of wire upon Send today for our great new book their primaries, and consequently a dead-end -"Inventions and Trade Marks, I Train You at Home switch is not necessary. Your coil presents many Their Protection and Exploitation" difficulties in panel mounting as well as in addi- and learn more about making to Boss the Job ! tional cost of contact points and sector switch, money from ideas than you ever without giving results north this additional ex- knew before. It tells many pense. things that are wanted, too. A postal will do- SELF-WINDING CLOCKS it is free. (794) Paul I.. help, Kurtown, Pa., requests our advice on a clock which will be wound up by We help our cliente an electric motor when the spring runs down. without charge, to get PATENTS A. You have discovered nothing new at all in t h e douars out of ADVERTISED in their ideas having your system of wiring an ordinary clock such - For SALE FREE the moment the spring runs down facilities none others manner that possess. or its power is nearly exhausted, it is rewound In Invention and again by an electric motor. This system is as old Advice Free. Manufacturing as the proverbial hills, and is used on many of Don't delay - get Supplement. the large clocks, as well as on many small ones. the book at once. The power clocks found in the large buildings of AMERICAN Published for the man with an idea. New York are all wound by electric motors as INDUSTRIES. INC. clocks installed in most offices and build- Send for free sam- are the 225 Patent Dept., ple copy. One year's ings. Two dry cells in these latter clocks op- subscription 50c. erate the motor to wind the spring. WASHINGTON, D.C. PATENT APPLIED FOR! (795) Arthur 11. Esbig, New York City, asks whether he can market a device with the words 1.25! elESTIOIVS "patent applied for" or "patent pending," and By which of the two terms he should use. MAIL tyINSWERS A. Any individual who has filed a patent in WILL MAKE the Patent Office, can go ahead and manufacture ELECTRICIANS -aid to ex- this article, labeling it Patent Applied For," and amination for license. Illus- I you a successful number has been granted he can label trations, diagrams, tables, etc. AUTO EXPERT, if the serial MARINE & STATIONARY EN- the device "Patent Pending." Any other manu- GINEERS-Latest answers to prepare you to go into facturer could also make this article at the same questiono asked at examinations; business for yourself, time, knowing full well that he was copying the profusely Illustrated. Price $2.50. train you for positions original design. By tedious processes of law this STEAM BOILERS-Conetruetion, care and operation. paying $3,000 to $10,000 be restrained from 170 illustrations; complete and valuable information. a year! Keep your job second manufacturer could Price $2.50. B. W. COOKE manufacturing the article, and after the patent is CATECHISM OF STEAM, GAS & ELECTRIC EN- -stay home-loan ins Directing Engineer granted, suit could be brought against the second GINEERING-Over 1,000 questions and answers. a part of your spare CHICAGO AUTO SHOPS royalties. If the second party Price $2.00. All books written in simple, concise time. As Directing En- party for back English by expert authorities. meanwhile goes out of business or is bankrupt, the READE PUB- CO-. 296 BROADWAY. N. Y. CITY gineer of the big CHICAGO AUTO SHOPS, recover nothing. If the second 1 train you the with books. first party can "JOB-WA Y"-not party will also enter a similar design for patenting, interference cases may spring up which will Patent Litigation result in court action to clear up the matter, cost- Trade Marks ing the first and second party a great deal of PATENTS Copyrights . money before either one or the other is forced to ® terms. Handbook of Instructions, "Inventive Knowlege" Free on Request PRODUCING DEAFNESS R. H. FRAVEL, Patent Attorney My home train- Formerly of the U. S. Patent Office Examining Corps ing makes Auto (796) Charles Fornen, Gainesville, Florida, Room 207. Stewart Bldg., Washington, D. C. EXPERTS! I pre- has stated that he often desired a device which you to BOSS would make him deaf at will, particularly when THEpare JOB! My 'Job - a cat howls or a trombone starts to play. He has HOME Become More Efficient be fitted Way" instruction makes you accordingly designed a vacuum cup to through courses in Mathematics, MASTER of every branch of into the ear and asks our advice regarding same. S TUDY History, English, Chemistry, automotive work: Mechanical, Elec- A. Referring to your suggestion of an ap- Psychology, Education, Busi- trical, Battery, Taxicabs, Busses, Igni- pliance to produce deafness at will, we would ness and 35 other subjects which the University Plants, the device may be patent- gives by mail. They command credit toward a tion, Farm Power Welding, Braz- advise that even though Bachelor degree and may be begun at xg, Vulcanizing, etc, You cannot get all able, and seems to you seemingly practical, it will any time. this training anywhere find no market whatever. Neither you nor I else on earth. would care to have rubber cups pushed into the Ztje gti nib trey of Chicago FREE OUTFIT! ears and then released, forming a vacuum which 27 Etlia Hall nhiraeo, III. Big repair and test- is applied to a very- sensitive organ, where the ing outfit free. Use Go into Business ! possibility of creating head noises, rupturing the it to do my JOBS, causing other damages is great. PATENTS use it to make moue, -make $5,000 to ear drum, and Trade -Marko, Copyrights and Patent Litigation use it to make this The device would be very uncomfortable and Write for advice and instructions how to proceed, training pay for it- $15,000 Yearly rather messy in operation. It is doubtful if the costs, etc. self! device would work as sounds are not all con- Hand Book with illustrations of 100 Mechanical Move- Biggest opportunities even attempting to ments sent free on request, FREE JOBS! to go into business with veyed through the ears, and stop up the ears by holding the fingers in them ALBERT E. DIETERICH Employment depart- small capital when you have get my training. Auto experts will not effect the propagation of sound, or com- Patent Lawyer and Solicitor ment helps You run own G. Co. big pay jobs without their business and pletely destroy its record in the brain. Successor to Fred Dieterich & of cost! make $5,000 t o $15,000 602 OURAY BLDG. WASHINGTON, D. C. One penny net profits a year. The same opportunity is open to YOU FARM ELECTRIC LAMP thru my guaranteed "Job - Idaho, has sub- NOW . Way" instruction. (797) R. Farnsworth, Rigley, p,c,,,-1- E N T S START mitted a design for a farm electric table lamp Inducements you cannot resist constructed as shown herewith. He asks our Hand Books on Patents. Trade Marks, etc.. sent free. Our to help you START RIGHT 7e years of experience, efficient service, and fair dealing os- advice. fullest lue and protection to th The NOW! Easy terms within your Scie American should be read by app invettors One week's pay as AUTO A. Your idea of an electric home light used entific reach. is of no value whatever, EXPERT pays for my wonderful - particularly for farms MUNN & CO.. III Woolworth Building, New York training. Let me tell you this The cost of construction is so great, and the com- Tower Bldg Chicago, Ill. wonder story personally. Mail mercial possibilities so small that we do not sug- Suëhd6c American Bldg., Washington, D. C. coupon or address: gest applying for a patent, nor do we believe that Hobart Bldg., 592 Market St., San Francmco, Cal. Directing you could even procure a patent upon the sug- B. W. COOKE Engineer gestion. You have complicated matters to such of replacement as well as DEAFNESS IS MISER CHICAGO AUTO SHOPS an extent that the cost I know because I was Deaf arid had Head Nets Dept. 428 the fussing with them renders their adoption very for over 30 years. My invisible Antiseptic Ea 1553 W. Madison St.. CHICAGO unlikely. Drums restored my hearing and stopped Hea mwsigamasmagfflIMMDIMMIMIMfflM Noises, and will do It for you. They are Tt Megaphones. Cannot be seen when worn. Etter B. W. COOKE, Directing Engineer HAT PINS rive when. Deafness is caused by Catarrh or b'I Dept. 428, 1553 W. Madison St., Chicago Perforated. Partially or Wholly Destroyed Naturar (798) F. George, Dark Harbor, Maine, re- Drums. Easy to put in, easy to take out. Area Please send me Free Book and complete pin, the design of "Unseen Comforts." Inexpensive. Write foe) information about your "Job -Way training quests our opinion of a hat is in the answer. Booklet and my sworn statement of how I recor- at home.' Tell me about the opportuni- which made clear eredmy ties today for Auto Experts, how to secure FREE REPAIR A. We would not suggest patenting any type hearing. as it were, a _ A. O. LEONARD OUTFIT. of hat pin. They are obsolete, passé Suite 369, -- New and we doubt if they will ever come back. A 70 StartAvenue York Citvi Name slight dent at the end of a hat pin will not secure it. Spiral shaft will render it difficult to push WL EDGE, BOO KSly Address the hair, to remove the same ADULTS! instructiveSEXKNO, authoritative profuse the pin through and illustrated in natural colors, etc. Not City State expeditiously. We would advise you to try your the cheap sort. Contains everything one should know both before inventive ability, which you have shown to be and after marriage to insure health and happiness. Large catalog Occupation Age quite acute, along other lines. Utilitarian devices 4e. O. F. SMETANA & COMPANY. OWOSSO, MICH. Science and Invention for April, 1924 1269 for home use, or toys and games, present the greatest possibilities. Particularly is this so, if you are in a position to manufacture or have these devices manufactured for you. Five- and ten -cent store devices on very small royalties also give TRADE-MDARKS very good returns for the investments. qM PATENTS COPYRIGHTS BOTTLE CAP FxAll[ (799) B. M. Gritz, Adams, Mass., requests Charge for our advice on a bottle cap with a lip which will OFFER- Instructions enable the same to be removed with the fingers. OUR tiad A. Referring to the attachment to a bottle stopper we are of the opinion that such a device, although slightly practical, is not by any means YOUR FIRST STEP marketable. Such a bottle stopper requires different types of machines for clamping the same should write around the head of the bottle. In addition to that, Before disclosing an invention the inventor it is expensive to manufacture. This is its great- This should be est drawback, and inasmuch as a cheaper article, for our blank form "Record of Invention." which performs this service equally well may be together with found upon the market, we would strongly advise signed and witnessed and returned to us against applying for a patent upon it. model or sketch and description of the invention for examination and instructions. No charge for the above information. cfientif lc ,, Ming' By H. GERNSBACK Our Three Books Mailed Member American Physical Society Free to Inventors from page 1198) (Continued Our Illustrated Guide HOOK How to Obtain a Patent the individuals, physical or sex attraction is full regarding U. S. lacking. Contains instructions Methods, Terms, and 100 Me- Second, we have a Sympathetic test be- Patents. Our tween the two individuals. In the upper left chanical Movements illustrated and described, hand is shown an attendant drawing blood Articles on Assignment or SALE OF PAT- from the hand of the young man or from ENTS, Patent Practice and Procedure, and any other part of the body. The young Law Points for inventors. woman is seen to be equipped with the same apparatus heretofore indicated except that the electrical sphygmograph is not em- Our Trade Mark Book ployed. Consequently, muscular contractions and sudden inhalations due to the excite- Shows the value and necessity of Trade -Mark ment with the attendant muscular relaxa- Protection and gives information regarding tions for sympathy, are recorded on a tape. Trade -Marks and unfair competition in trade. Unless a certain maximum is reached, it would show that the sympathetic reaction of the girl is not sufficient. The same tests Our Foreign Book must, of course, be made with the girl in We have Direct Agencies in all Foreign Coun- order to give a similar reaction check on the man. tries. We secure Foreign Patents in shortest Third, probably more marriages are time and lowest cost. wrecked by unpleasant Body odors than from any other cause. A bad bodily odor CO. or a bad mouth odor may turn love into VICTOR,J~EVANS & dislike. In the upper right hand illustra- VICTOR BUILDING 779 -9?M ST., N tion, we have shown where the candidates are made to breathe each other's body odors -not a pleasant performance, but very necessary, if we would not be prudish. It is better to find out these things before we are married than when it is too late. Fourth, Nervous disorders have wrecked a large percentage of marriages. The two mating individuals should under no circum- stances be extremely nervous. If the man u"`° is calm and the woman very nervous or i I r A_ vice versa, no great harm is done, because Nature tends to equalize opposing forces. .t `"D SyiÁfiT,S PATENT OPPICr, The mischief begins when both individuals are extremely nervous. It can then be predicted with certainty that their married life will not work out satisfactorily. In the WE REGARD A SATISFIED CLIENT lower right illustration, we have shown how As our best advertisement, and will furnish to anyone, upon request, lists of clients in both individuals are equipped with the same any state for whom we have secured patents. apparatus before described. Then unknown to them, a sudden loud noise, such Highest References-Prompt Attention-Reasonable Terms as the firing of a revolver, is produced. The nervous reaction of the two candidates WRITE TODA Y can be checked up nicely on a tape, and if both show the same reaction, marriage VICTOR J. EVANS & CO. should not take place. Free Of course, there are many other tests Patent Attorneys can be suggested to complete the New York Offices Philadelphia Offices Pittsburgh Offices which 1007 Woolworth Bldg. 714-715 Liberty Bldg. 514 Empire Bldg. testing of the marriage candidates, but the Chicago Offices, 1114 Tacoma Bldg. San Francisco Offices, Hobart Bldg. four cited here are probably the funda- Coupon mental ones and therefore the most impor- Main Offices, 779 Ninth Street, Washington, D. C. tant. Gentlemen: Please send me FREE OF CHARGE your books as described above. Enlarged views of the tambour, manometer and chest device far operating the Name Address tambour are also shown. 1270 Science and Invention for April, 1924 Radii® Wie (C-t>ntinued from page 1265)

.I,,.11, 1I I,,,,n,,,,,,,,,,,,, I I,,II,,,,,,,,,n,,,,,,,,,,,,,,,,,,,,,,,,1,

A LOUD TALKER HORN

SOLDER TIN BOWL WITH AROUND HOLE CUT TO EDC1 E5 FIT h ORN

hORN CUT TO FIT BOWL One of the Seven Laboratories AT THE SCHOOL OF ENGINEERING OF MILWAUKEE Where ELECTRICITY is Taught Quickly and Thoroughly BECOME A MASTER ELECTRICIAN IN ONE YEAR or learn an electrical trade in three to six months. Greatest of all professions open to you. "Forty billions will be invested in Electricity in next five years," says Edison. Salaries are high. Demand for TRAINED electricians ENORMOUS. Think of electric lighting, electric street cars, electric railway trains, electric telephone and telegraph, electric motors, electric automobiles, electric cooking and heating. Electricity in the air and under the sea. Is it not dazzling? FIELD LIMITLESS-NEW-UNCROWDED CLIP HERE Our large staff of professors of the four departments Mall This Coupon Today-Right NOW teach the laws and principles of electricity. Actual School of Engineering of Milwaukee AMPLI FYINCl UNIT HELD training in laboratories: lectures and practice. No SI -424B, 415 Marshall St., Milwaukee, Wis. special schooling required to enter our practical elec- Without obligating me, please furnish details of IN PLACE WITh WOOD BLOCK trical, electrotechnician and trade courses. course (or courses) marked below: Master Electrician, 6 months to 1 year. "Earn While You Learn" if you wish. We arrange Iciectrotechnician, 12 to 30 months. half-time employment that will help you defray ex- Electrical Engineering, B.S. Degree, 3 years. Board and room rea- penses. Lakeside advantages. Commercial Electrical Engineering, 12 months. An excellent loud talker horn may be made from the parts sonable. Daily broadcasting WIAO. School orchestra. Automotive Electricity, 3 to 6 months. Fraternities. Wonderful co-operation between student Armature Winding and Motor Generator Re- of an old automobile horn. A large bowl made of rather and Instructor. pair Course, 3 to 6 months. heavy gauge metal, so that it will not vibrate excessively, Catalog explains in full. Send for it. Electrical Home -Study Training with labora- is first obtained and an oval shaped hole cut in its bottom. tory facilities to those who cannot come It will be noted that the less the horn tends to vibrate, to Milwaukee. the better will .be the quality of music and speech repro- SCUD!. of ENGINEERING Name duced. The upper end of the horn is then cut to fit the of Milwaukee Street hole in the base of the bowl. A little grinding and cut- exact fit is obtained. 415 Marshall St. S.I.-4248. Milwaukee, Wis. City State ting will be required here until an Age Education The edges of the joint are then soldered. The entire unit may then be painted black so as to present a good appearance. An amplifying unit of any of the well made types is then placed within the part of the horn which formerly held the operating mechanism. The diaphragm of the original horn must, of course, be removed. The amplify- PROTECT ing unit is held in place by means of a wood block which is of such a size that the cap of the phone will be held YOUR IDEAS rigidly against the base of the horn. The leads from the INVENTORS phone are to he brought out through a hole in the base. -Glen F. Stillwell. Send for our Guide Book, HOW TO GET A PATENT, and Evidence of In- terms, methods, etc. Send vention Blank, sent Free on request. Tells our WIRE SCRAPER model or sketch and description of your invention and we will give our Name opinion as to its patentable nature. NOTCH FILED EDGES SHARPENED -y Street RANDOLPH & CO. City State Dept. 172, WASHINGTON, D. C.

YOU TOO CAN PLAY THE HAWAIIAN GUITAR T. Y P E W R IT ER JUST AS THE HAWAIIANS DO! T'urs'.eeunconditioneii PLAY ALL THE LATEST HITS 10 DAYS FREE TRIAL returned if at d f to BROKEN days you are not metalled with thin late model prone. WOOD typewriter rebuilt by the famous Shipman Ward process. After Your FIRST LESSON You BL APE e Will Playa Complete Selec- GREAT PRICE SAVING íP1,7 sttt°yáew=iieift. tory in the world by our money easing metbode. tion. We Guarantee That -- Somali Our method is so simple, interesting EASY MONTHLY PAYMENTS aght and appealing that you begin in your notice it while you enjoy the use of this wonderful machine. first lesson to learn the famous Ha- k Explaining Shipman wai i anFolk Song"ALOHA".Thin FREE BOOK OF FACTS Ward's wonderful how happy you will be when you - of rebuilding typewriter. and also valuable information surprise, your friends by playing :LemMom, the typewriter industry both instructive and entertaining. the fascinating Hawaiian Guitar. Only Four Motions -- and You Master Them Quickly! Ina few minute. you acquire the four motions necessary to play amp pleoe--after that .short period of practice and you will have mastered Act Today! 5 this weirdlysweet music. Complete course of 621eesons includes sae. Mail beautful Idaweiian Guitar, necessary picke, steel bar, etc. No extras. Year No Previous Musical Knowledge Necessary Coupon Guarantee If you never rend mu:drat note in your Ulo.-if you haven't even the .lightest know ledge of music wec quickly and 4 .tivelsteach you in a perfectly toRla this wonderfully popular netrument. Don the Just bated. Many are the nicks which have been put sr when you eau curdy be the center gfsnterest aongm your friends. good pocket knife blade by scraping the insulation from Over 4Ó,00O successful students. wires. Very often a blade is broken in this process. If Just Mall a Post Card for Details this the broken blade may still be made to give ºsome send io f our remarkable FREE HawaiianGuitar Of - happens, Shipman Ward for --simply write:' lam interested"- very good service by grinding a notch in it and tiling the Mfg. Company fers hooky of farte. but do it today. a explaining bargain offer. edges sharp, as shown above. Even in a knife without 2164 Shipman Building First Hawaiian Conservatory could be placed the base Montrose & Ravenswood A Beautiful broken blade, such a notch near of Music, Inc. of one of the blades without interfering with its original Aves., Chicago sypea iqt nm r,e. o Desk 40: -233B'dway Hawaiian filed notch Spoon, -Ban- (Woolworth Bldg. ) purpose. By using this in connection -With the Name *,1151,,,,,v,7-"-Fi Bosect New York City Guitar thumb, insulation can be quickly and easily striped from St. and No wire. The sharpened edges of the knife blade will be saved City State from damage. -Stanley Robinette Science and Invention for April, 1924 1271

SPIDER -WEB COIL MOUNTING

---SPIDER-WEB COILS

MOVING G IL 111M

PANEL' STATIONARY 1C OIL

KNOB LOCK- NUTS

U511 NC¡

Learn Public Speaking

ESSONSESSONS lo' Write - quick - for FREE, BRASS STRIP particulars of this extraordinary MOUNTING offer; an opportunity you will never forget if you take advantage of it. Ten lessonst in effective publit speaking to our course When spider -web coils are to be mounted back of a panel, absolutely FREE to those who'act promptly, introduce the procedure outlined above may be followed. One of the in localities where it is not already known. coils is mounted on a block in a stationary position. The other one has fastened to it a piece of fairly heavy brass influence strip. A hole is drilled in the end of the strip and a We teach you by mail to become a powerful and convincing speaker-to short length of brass rod fastened thereto by means of lock and dominate the decisions of one man or an audience of a thousand. We have trained nuts. This brass rod passes through a bushing in the panel hundreds and helped them to increase their earnings and their popularity. Learn, in and a knob is fastened on the outer end. A spring inserted of between the lock nuts and a washer on the end of the your spare time at home, how to overcome "stage fright" and conquer fear others; bushing serves to keep the spider -web coil in the position how to enlarge your vocabulary; how to develop self-confidence and the qualities of in which it is set and prevents the possibility of the hori- leadership; how to RULE others by the power of your speech alone; how to train your zontal distance between the coils varying. --.lames Williams. me. -mury. Our WHAT THE COURSE ,,,,,,,,, ,,,,,,,,,,,,1,11,,,..,,,1,11,,,,1,,,,,,,,,,11,,,1,1111,,,11,,,,,,,,,,1,,,,,,,,,,,,,,,,,,,,,,,1111,1111,11,,,11,,,,,,,,,1,,, TEACHES YOU New Easy Method How to talk before your club or lodge; perfected and taught only by Prof. R. E. Pattison CHEAP DIALS Homy to address board Kline, former Dean of the Public Speaking Depart- meetings; ment of the Columbia College of Expression, can be learned in 15 minutes a day. Prof. Kline is one of How to propose and re- the foremost authorities in the country on public speak- spond to toasts; ing and mental development. Do not let this chance How to make a political escape you. speech; Flow to tell entertaining stories; Flow -din- Limited to make after Offer ner speeches; Send This Free Coupon Now Ho-w to converse inter- estingly; This Special Offer of TEN LESSONS FREE is made How to write better let- strictly for advertising purposes and will be with- ters; drawn without notice. Write now, before it expires, and receive full particulars with enrollment blank by How to sell more goods; return mail. No obligation of any kind. Just tear off How to train your mem- and mail this free coupon-or a postal will do. ory; How to enlarge your vocabulary; How to self- 0!IIt develop confidence; FREE LESSONS COUPON How to acquire a winning personality; NORTH AMERICAN INSTITUTE, How to strengthen your Dept. 7444, 3601 Michigan Ave., Chicago, Ill. will power and ambition; I am interested in your coursé in Effective Public How to become a clear, Speaking and your offer of ten lessons free. Please accurate thinker; Old phone diaphragms which have become bent or dented send particulars. It is understood that this request and are no longer useful in their original purposes can be How to develop your places me under no obligation of any kind. made useful as small dials for rheostats or potentiometers. power of concentra- A scale may be engraved on the diaphragm with a sharp needle and a hole drilled through the center of the dial. tion; The shaft is then passed through and a knob screwed on How to be the master of the outside. A lock nut drawn up on the back of the diaphragm holds the unit rigidly. These dials will present any situation. even a better appearance if they are enameled white and the graduations put on with black paint. 1272 Selene(' and Invention for April, 1924

PUSH-PULL AMPLIFIER

"I keep siihonest, serinQ merci; (They/aught me all /kneul): Their names are WHATand WHYand WHEN; WHAT? WHY? and HOW and WHERE and WHO. HOW? WHERE? WHAT was the Declaration of Lon- HOW can you distinguish a malarial don? WHAT are consols? mosquito ? WHY does the date for Easter vary WHERE is Canberra? Zeebrugge? from year to year? Delhi ? 0.11 WHEN and by whom was the great WHO was Mother Bunch? Millboy F- pyramid of Cheops built? of the Slashes? Are these"six men"serving you too? Give them an opportunity by placing 1

wtlLNL WEBSTERS NEW INTERNATIONAL WHO? The DICTIONARY ér in your home, office, school, club, shop, library. This "Supreme Author- ity" in all knowledge offers service, immediate, constant, lasting, trustworthy. Answers all kinds of questions. A century of developing, enlarging, and perfecting under exacting care and highest scholarship insures accuracy,completeness,compactness, authority. The New International is the final authority for the Supreme Courts and the Government Printing Office at Washington. NEW WORDS Write for a sample page of the New Words, Thousands have been added. specimen of Regular Papers, prices, Can you spell, pronounce, and India etc. and define them? To those naming this magazine we will send free a set of Pocket Here are samples: Maps. G. & C. Merriam Co., Springfield, Mass Lecho -Slovak capital ship Junior college mirrorscope G. & C. Merriam Company Gentlemen : Send sample page of NewWords, Murman Coast marquisette specimen Regular and India Papers, free Springfield, Mass. Est. 1931 maps, per Science and Invention. 4 Name and Address Those desiring a push-pull amplifier without going to the expense of buying two push-pull transformers may use this circuit with excellent results. In this circuit dry cell tubes are recommended, as separate "A" and "B bat- «A» teries are required. One amplifying transformer of any standard make may be used, connected as shown. It will be noted that when one grid is negatively charged; the other is positively charged, thus giving the true push-pull MARKO BATTERY effect. As one loud speaking phone is required for each 90 AMP. HRS. tube, those having a pair of loud speaking phones may use it to advantage by connecting the phones as shown and attaching them both to one horn. -C. Fitch. IN RUBBERLITH CASE Ornamental As Well As Efficient

The Rubberlith case is a composition case with ROTOR MOUNTING a high gloss giving the appearance of ebony. It is moulded in one piece, including handles and cells- no jars to break-and is practically indestructible. A worthy addition to your set. ALL SIZES, FROM 2 VOLT BATTERIES UP, CARRIED IN MAHOGANY FINISH CASES DISTRIBUTED BY ROD FOR MARKO STORAGE BATTERY CO., 210 West 54th St., New York, N. Y. SWITCI1 LEVER MARKO STORAGE BATTERY CO., 102 Jefferson Ave., Brooklyn, N. Y. NATIONAL LIGHT AND ELECTRIC .CO., 289 Market Street, Newark, N. J. RADIO DISTRIBUTING CO., 8 W. Park St., Newark, N. J. VERMONT RADIO CO., Richford, Vermont. CARD BOARD TUBE THE FOR WINDI SCHIMMEL ELECTRIC SUPPLY CO., 526 Arch St., Philadelphia, Pa. ROTOR CONSOLIDATED WIRE & ASSOCIATED CORPORATIONS, Green Sc Con- SWITCH LEVER COLLAR Sts., Chicago, Ill. gress BRASS ELECTRIC CO., Inc., 66 Allen St., Buffalo, N. Y. STRIP WEINIG URBAN SOLDERED TO Sold by Radio Supply Stores and all Marko Service Stations BRASS MADE BY TUBE BRAS MARKO STORAGE BATTERY CO. SW IT 1402 ATLANTIC AVENUE, BROOKLYN, N. Y.

raw. MAKE MONEY I\HIoIÉRlllylltill;¡ $ 1 IIII' AT HOME Postpaid Y OU CAN make $1 to $2 an hour writing show with cards at home in your spare time. Quickly and easily learned by our new simple method. Instructions No canvassing or soliciting. We show you how, guarantee you work at home no matter where SEND FOR YOUR FREE COPY you live and pay you cash each week. Full particulars and booklet free. Write to -day. AMERICAN SHOW CARD SYSTEM LTD. TESTED Authorized and Fully Paid Cappital, $1,000,000 110 Adams Bldg. Toronto, Canada SPRING BRASS COLLAR HOOK-UPS BOLTED TO TUBE SUBMITTED BY USERS OF OUR FREE awonderful IT"ONDERFUL TRANSMITTER Book on Finger Prints In some circuits it is very desirable to have a tapped rotor. BUTTON FOR LOUD SPEAKERS This may readily be accomplished by following the draw- Full of thrilling crime mysteries solved ing given above. A small panel is placed within the rotor AMPLIFICATION EXPERIMENTS through finger print evidence by America's greatest experts. Gripping illustrations. True stories. and a switch arm is arranged so that it can be con- learn the creep re trolled by means of the rod passing through the brass Special you tube which latter serves to turn the rotor. The illus- K. ELECTRIC CO. Offer Wray today. Gat tú1Ì detetl.. Big unwise In store for yon. Book sad offer free. Writ, now. tration above shows all the necessary details for the con- 15 PARK ROW NEW YORK UNIVEÁSITY OF .5334CIENCE struction of this useful addition to any radio set. 1920 Sun. side e t -Herbert C. Leonard. Science and Invention for April, 1924 1273

D. P. D. T. SWITCH

BAKELITE PANEL Announcing the "GEMPHONE» the $lv' ITCH BLADES SWITCH DOLLAR POI NTS 1000 ohm ARM INSULATING SOLDERED STRIP ADJUSTABLE TO SWITCH BLADE PHONE Adjustable -Rubber Don't judge the "GEMPHONE" (Patent Pending) FLEXIBLE JOINT by its price. It is the cheapest radio phone on the market but its exclu- with 3 ft. Cord PANEL sive features place it in a class by Shipping Charges Prepaid itself. Its performance, the clarity to any point in the U. S. TOP VIEW and volume of sound reproduction, the faithfulness with which it reproduces radio broadcasting and code, A simplified double -pole double -throw switch which can be operated from the front of the panel is shown above. Th the exquisite quality of tone to- This Complete Radio motion for changing the switch is very simple, it being only gether with a remarkably loud and necessary to push or pull the knob. This switch could b clear volume, make it the equal to, Receiving used very readily in connection with the method of "In- in of, creaing Capacity," which was described in the Radio and many cases the superior Set Wrinkle Column on page 945 of the January issue. The phones at three and four times its Consisting of two switch blades and the arm are cut from stiff spring price. Radiogem brass and the arm soldered to one of the blades. If pos- is sible, the arel and one of the blades should be cut from The "GEMPHONE" of stand- Gemphone the salve piece of material, as a stranger joint will result. ard type and made of the very best and Aerial A hole is then drilled in the other end of the arm and a grade of materials throughout. It piece of brass rod bent to fit therein. This rod extends though the panel and has a knob fastened to the other end. is adjustable-one set screw enables $250 T. L. Stalker. you to adjust the phone to secure perfect reception under any condi- This outfit la absolutely complete. It tion. includes everything The case is made of turned wood, you need to hear the Broadcast Programs, an exclusive feature with the market reporta, time is signals, ship calls or "GEMPHONE." This feature lad a t at hi ion n mes- responsible for its exceptionally sages.n Nothing more (Patented Jan. 8, 1924) to buy-no batteries REPAIRING PANELS rich and mellow tone. or tubes needed-no upkeep of any ]rind. The simplest radio outfit made-yet as Practical The "GEMPHONE" is sold un- as the most expensive. A crystal receiving set that assembled. The coil is wound to you can operate and enjoy even though you know absolutely nothing about radio. You receive the 1000 ohms-all you need to do is RADIOGEM unassembled, together with a clearly SEALING WAX written instruction book, which shows you how to to place the parts into the case, quickly and easily construct the set, using only tighten up the adjusting screw and your hands and a scissors. The instruction book explains simply and completely the principles of MATC connect the terminals and cord. radio and its graphic illustrations make the as- Our instruction pamphlet shows sembling of the RADIOGEM real fun. how to assemble it in two minutes, Price of Radiogem without phone or aerial. $1.00 using only a screw driver.

Order Direct or From the Following Dealers : Akron, Ohio Dallas, Texas Laurel Springs. N. J. Omaha, Neb. II. Kaplan Radiogem Cullum \ l;uren Co. Stung .\ huait Iturgess-Nash Co. Agency Fredricksstad, Norway Los Angeles. Calif. Oregon City. Ore. Astoria, Ore. Heider Lund Lester's Radio Shoppe Singer Hill Radio Service Cook & Foster Gary, Ind. Medford, Ore. Philipsburg, Pa. Brooklyn. N. Y. Tribe of K Virgin's Radio Service A. 0. Curtis Pullman, Wash. I). S. QualeY Grand Rapids, Mich. Media, Pa. Pales. Supply Store PANFL. Buffalo, N. Y. Speeia It y Sa les Bureau Media Eler. Co. Saginaw, W. S. Mich. Eier. Supply & Equip. Co. Hawera, New Zealand Melbourne. Australia T. A. Looted & Co. Burlingame. Calif. lt. H. Blake Marks & Abrahams, St. Louis, Mo. IJuold Cooley Havana, Cuba Pty. Ltd. United Supply Ca Capetown, South Africa Comp:Iola Radiotelefonica New York City, N. Y. Seattle, Wash. 11. J. Williams dc e Dixie Supply Co. Frank it. Wilson Chicago, Ill. 5f. Maisa'ubano Consrad Co. Springfield, Ohio Barawik Co. Manuel Nodar, Jr. Radio Specialty Co. Moore Sales Service Home Supply Co. Radio Novelty I Jerold M. Schwab Syracuse, N. Y. International Industries Hoboken, N. 1. Norfolk, Va. Syracuse supply Co. Cleveland, Ohio C. R. Prfeman Co. P. J. Sawyer Washington, D. C. Anderson Elec. Co. Holyoke, Mass. Northampton, Mass. Capital Radio Co. Service Publishing Co. The Johnson Co. Parsons Eler. Shop J. T. Smyth

THE RADIOGEM CORP., 66 -S -West B'way, N. Y. City DEALERS --Write for Prices and Circulars.

Charrin Pays RUB WITH FINE SANDPAPER HB BiBattery Months Prot'its IN ONLY ONE DIRECTION 8 HOUR Make $ 150 to $300 monthly charging batteries. Start now to build your own money -making business. No experience needed. Buy an HB 8 -Hour Battery Charger on long easy terms, more than paid by big monthly profits. Small cash payments buts HB outfit in your shop, 30 days' freo trial on money -back guarantee. Only $20 monthly pays Very often it is desired to use a panel for a certain infor your outfit. No repairs, no expensive renewals. Store strument which has holes drilled in it which cannot be lilt outfits in use than any other make, Write hulay for BROS. Box S4, Troy, Ohio used. If left in this condition, the appearance of the information. HOBART CO., instrument will be spoiled. Therefore, a piece of sealing Profits Easel Carry Small Month \ Pa -Tits wax is obtained of the same color as the pastel and heated. The drops are allowed to fall into the holes on the panel, which is placed on a smooth surface. The panel Insure your copy reaching you each month. Subscribe to Science and Invention can then be finished off with a piece of fille sandpaper, Co., 53 Y. rubbing only in one direction. If the process is gone -$2.50 a year. Experimenter Publishing Park Place, N. C. through correctly, a neat job will result. -Bud Mulkeyn. 1274 Science and Invention for April, 1924

HONEYCOMB COIL CONTROL "My HAMMOND Does Many Things No Other Writing Machine Can Do" THE New HAMMOND serves a host of INAICATINq SCALe in our business no other typewriter could satisfy. Its changeable type and its variable spacing features are wonderful advantages. The condensed writing is invaluable in getting out our sales manual and in keeping up my loose leaf pocket reference book. In preparing advertisements the various type sizes and arrangements are helpful in making copy fit the layout. The personal touch which the use of occasional italics gives my letters has greatly increased their pulling power. In handling ex- port correspondence in foreign languages and in JllültróYlwliliúll countless other ways the HAMMOND gives new value to typewriter j usage." aurn'n`mro TYPEWRITE R SHAFT KEYED VARIABLE SPACING TO SASE OF CHANGEABLE TYPE MOVINC1 COIL Write for The New Folding Hammond has New Illustrated Booklet every feature of the desk style machine yet weighs only 83 lbs. HAMMOND TYPEWRITER CORP'N. 554-A East 69th Street New York Here's What Hammond Variable Spacing Actually Does! hG1COCI1CC6 (18 Characters to Inch) i''illiüiilii (14 Characters to Inch) RASS ANC4LE MQVIN4 'COIL 33:::Dlang 1:1EI11:9 (io Characters to Inch) Tf1READED BU511

1 2

A well -made and accurate control for honeycomb coil which are mounted in back of the panel is illustrated above. An indicating dial is also arranged so as to show th The "Rico" Grand Opera position of the movable coil. The movable coil is mounted Loud Speaker Unit on a wooden block and a shaft, which passes through two Patented, December 25, 1923. brackets. The shaft is placed in position and fastened with a set screw. A brass angle is then screwed to the side of the block. The entire assembly is You have read no doubt that every loud -speaker is posi- made as shown tively the best manufactured. We in the two illustrations above. Screwing the small knob could make similar in or out, varies the angle between the two coils. As claims--on paper-and perhaps go the other one better. dial turns, a number is visible Modesty, the outside the panel, however, forbids. For that reason, we make this indicating the position of the movable coil. -F. R. Thresh. statement:

Get a "Rico" Grand Opera Loud-Speaker Unit. Compare it with ANY loud -speaker that you have ever heard. Merely ,tnaanna ,,uo ann,nncnn,nn rn.nern area ran a en an na Iowa nrnannnnnnmmennntntnnnna consider that the money you have paid for the "Rico" Unit is on deposit. If after five days you find that the "Rico" Grand Opera Loud -Speaker Unit does not give you VARIABLE SPIDER -WEB COIL greater volume and greater clarity of sound and greater joy than any other loud -speaker unit, then our dealers or TURN CAP ourselves will be glad to refund the purchase price. TO ADJUST DESCRIPTION: This loud -speaker unit is ideal for phonographs. With this unit you can turn your graph phono- into a loud -speaker. Any good horn, however, can be attached to it. Speaker does not work with crystal sets, only on vacuum tubes. mamma 11ään. , , , ,,,,,,,,, ,,,,, , ,, you can get either tremendous volume or No Metal Can Touch the soft tones as desired. Aluminum shell and cap highly nickel - Diaphragm plated and polished. Five-foot furnished. green cord Thi> is a feature not found in any loud- No. 75 "RICO" GRAND OPERA LOUD - SPEAKER UNIT speaker except the "RICO" GRAND OPERA Price, as described. 1.OUD-SPEAKER UNIT. Diaphragm can- $7.50. not rattle. Metallic, harsh sounds are entirely eliminated AND the "RICO" GRAND Radio Industries Corporation OPERA LOUD -SPEAKER UNIT is fully adjustable. For light or soft tones, simply 131 Duane St., New York City turn the milled rim. With this arrangement Cable Address: Rientrate, New York S. & I. 4.24

il FEET LONG "Lighting Fixtures" 11 INOiES Separatoff DIAMETER Ready to hang. Insulator Subamte for Ouude Antenna _,Separator Direct from manufacturers. 70 Feet Stranded - r w,,, Insulator wired including A receiving set using spider -web coils is not always as Completely T mbucWe 1R' NOT A LOOP r as glassware. W _ BUT A FULL SIZE ANTENNA flexible might be desired. This can readily be remedied Q .'r ¡/ Sutpend 1 by Send for Catalogue No. 24 m doubletone mounting a switch arm on an elongated vane of th Qaein¢ far ºa near Special Proposition to Dealers COMPLETE ` h cease* antenna coil. The end of the arm makes contact with the wire in POSTPAID ding a path where the insulation is removed. ERIE FIXTURE SUPPLY CO. Unaffected by WInd- Rain-Sleet- Lightning One connection is made to the end of the coil and the other to the switch Desk B Erie, Pa. INTER -STATE SIONALM,COLUMBUS,OHIO arm. The remaining end of the winding has no connection. -K. Andersgn. Science and Invention for April, 1924 1275

SOCKET MOUNTING

OCKET.

BLOCK THIN RUBBER

I k

SUPPORT INCa BLOCKS

P' Each Serves Its Community In Frazer, Colorado, a log cabin of three rooms shelters a telephone exchange that connects with the mountain homes of cowmen, miners, homesteaders and tie -cutters. In the heart of New York City a new building of twenty- PIECE OF TrIIN 'RUBBER CUT TO SHAPE nine stories is to become the home of several metropolitan central offices serving some 120,000 telephones. This Particularly with the new types of vacuum tubes eperatin building will contain, as well, offices for executives and for on one or three dry cells, the microphonic action i noticeable. This takes the form of loud noises and sound engineering, commercial, plant and accounting forces, pro- similar to bells in the phones when the table or receivin set is tapped or jarred. Sometimes the sensitiveness a viding space for over 7000 telephone workers. the tubes is so great that the vibrations caused by a per son walking in the same room will cause annoying sound Each of these buildings helps to render adequate and in the phones. This can very often be eliminated, or, at least, reduced to a considerable extent, by mounting th economical telephone service in its own community. They socket in such a manner that the vibrations will be ab extremes personnel. sorbed. Such a mounting is illustrated above. A piece o stand at the in size, equipment and rubber of the correct size is cut from an old inner tub Yet they both indicate the nation-wide need for adequate in the shape shown at the bottom of the above illustra tion. The four ends are then fastened to supportin housing of the activities of the Bell System; and they illus- blocks and the socket fastened to the center. If necessary the socket may be supported by another wood block. trate the varied ways in which that need is being met. One -John Rulison of the largest single items of plant investment of the Bell System is real estate, comprising nearly 1700 buildings acquired, with their sites, at a cost of $180,000,000. It is continuously the aim of the Bell System to construct CONDENSER SWITCH and so to situate each new building-whether executive office, central office, storehouse or garage-so that it shall AERIAL-- serve its community with the utmost efficiency and economy, and remain a sound investment throughout its period of life.

PHONES AMERICAN TELEPHONE AND TELEGRAPH COMPANY AND ASSOCIATED COMPANIES VARIABLE CONDENSER BELL SYSTEM CRYSTAL One Policy, One System, Universal Service SWITCH DETECTOR -1 E19- 10Ô 1 PAGES CATALOG FREE DIG MONEY Latest Reflex and Neutrodyne Circuits INA BIG FIELD EVERYTHING IN RADIO Wanted and wanted quick One of the largest complete stocks in the are men who- can qualify for big pay positions in the coot, world. 40 diagrams of latest Hookups. moos, fast growing Radio Industry. Once in a lifetime chance. Fast, easy to learn. No previous experience needed DEALERS ALL OVER THE U.S. Making big profits handling our supplies. 24 -hour 13e :NRadio-Expert service. Goods shipped same day order received. _ 143.000 to#10.000aäea Learn at home, by actual practice, to design,construct, ins tall,operate,repair and sell Radio Equipment. Pleas- ant, fascinating, profitable. My methods are simple, clear and successful. Turn your spare time into cash. TO GROUND WONDERFULIOoo MILE TUBE RECEIVING SET. FREE Write today for Booklet "Radio Facts" FREE. R. G. kehaupt, Radio Eng.. AmerjGan Radio Association 4513 Ravenswood Ave.. Dept. 134 , Chicago The switch in the above diagram was placed therein in WHOLESALE RADIO DISTRIBUTORS order to simplify the tuning. If you are not sure that Dept. F. 6 W. 14th St., Kansas City, Mo. your crystal detector is in adjustment, throw the switch to the left, thereby cutting out the condenser. The tuning will he broadened and you may be able to hear several Insure your copy reaching you each month. Subscribe to Science and Invention stations at once. Adjust the detector, throw the switch to the other point and vary the condenser until only the -$2.50 a year. Experimenter Publishing Co., 53 Park Place, N. Y. C. desired station is heard. -Monroe Richie. 1276 Science and Invention for April, 1924

ANOTHER VERNIER

3 p'ia/ on shaft of instrument,

Choose asYour ElectricalProfession GET THE FACTS about the high -pay opportunities in Engineering Electricity offers a brilliant future to the young man who is about to choose his career. Never be- ELECTRICITY fore has there been such wonderful opportunity in this great field. Big paying positions in electrical Do you want the real, "brass tacks" work the world over are open to Edge of 3".''W B. S. Degree trained men - men who possess facts about your chances in the elec- qnd specialized, practical knowledge. ground f/o/ in 3 Years Come to the School of Engineering trical field? groole'd of Milwaukee - the largest and A big new 64 -page book issued by the As- best equipped electrical school In America. Here you are trained in both theory and practice by a faculty of ex - sociated Electrical Engineers of America, gives LArge arils. You learn in large, finely equipped laboratories. you thesef acts, straight from the shoulder! Here If you have 14 high school credits or equivalent, you knob; ran become an Electrical Engineer with a Bachelor of is the answer to your questions. You can have Science degree in 3 years. If you lack these credits they can be matte up in our Institute of Electrotechnies In a it-FREE-by asking for it on the coupon below. Gasher Washer short, intensive course. as Never Before Earn While You Learn NOW Your Chance is in By our special system you may earn your way while learning. Our Employment Department will secure you the High -Pay ElectricaiJobs a position to which you may devote a part of each day. You may think, right now, that there isn't as big an spending the remainder at the school. This plan both solves opportunity for you-in electricity-as we tell you the students' financial problems and provides splendid there is. But the bed -rock facts of the case show be- experience at the same time. Summer Term yond question that there is an ever increasing short- Low tuition fee. Board and age of trained electrical workers, a shortage that room reasonable. Daily Broad- Be g ins can't be overcome for five years, at least. Locknufs cast ing WlAO. School Orches- If you want to know-if you want to be convinced- Smp// knob, tra. Fraternities July1st. you'll find the facts you're looking for, in the pages grooved of our great book. You'll find out why you can Write for Catalog ,Dane/ Write today for our free, illustrated catalog. Read EARN $15 TO $30 A DAY AS AN about this wonderful institution and the great opportunities ELECTRICAL EXPERT OR IN that, lie before you. Find out about our specialized method of training and the details of our "Earn While BUSINESS FOR YOURSELF To snake titis simple and efficient vernier first remove the You Leant Plan. Spare time training at home, under direction of the dial from the instrument and grind the edge flat. Then A.E.E.'s engineers puts you in line for the sort of op- run a fairly deep groove all the way around the edge, as portunities you are seeking-real jobs, with real pay! shown at A. Mount two knobs as shown at B, directly orENGINEERING NEW, COPYRIGHTED METHOD below the dial. Assemble the instrument on the panel and of Milwaukee place the two knobs as shown above. Run a belt or cord Dept. SI -C424, 415 Marshall Milwaukee, OF TRAINING GETS RESULTS around the two pulleys thus formed. The small knob will St., Wis. Your progress under the A.E.E. methods of training give a very fine variation. -W, D. Chandler. is swift and sure. Practical, clear, understandable School of Engineering of Milwaukee, information covers every branch of Electricity-Gen- Dept. S I -C424, 415 Marshall St., Milwaukee, Wis. eral, Automotive, Radio, and the Business side, too. Please send me your free illustrated catalog on Elec- Nothing else like it. Shows how to make more money ,1111 11111111j.1.11111111111111111111111,114.1.0111111.Mw111.,,,1.non,nn,u,,,,,,,1,uunnnmu,uunnn,,,,,,, trital Engineering and give me the details of your "Earn right from start-how you can Earn while you Learn. While You Learn" plan. DON'T LET LACK OF Name EDUCATION STOP YOU SOCKET TESTER Address You don't need much book -education to get the Town State meat in this training. Everything in it is perfectly Age Education clear and understandable. Backed by a Legal Guarantee of Satisfaction How to Get More Money You're not taking the slightest risk in send- SEND ing for our book, or You want one of the big jobs listed in taking our training, below. You want promotion and con- either. If you train in stantly increasing salary. You want your 14 the A. E. E. you are position to be permanent. You say: "Of OW backed course I do, but how? There is no secret byastraight. formula for success. You will be surprised legally binding how easy it is to get ahead, once you are Electrical guarantee of satis- shown how. Check the job you want, send us About faction that pro- the coupon and we will explain, without ob- tects you every step ligation to you, how to get the job you want. moduo,ties of the way. So once again we say,"GETTHE FACTS." Write us right now for copy of the book. Pick thelob You Want! ASSOCIATED Tell me how I can get the 'ELECTRICAL ENGINEERS Job and Money checked I Here's Opportunity's Wide Open Door 7-1 Carpenter & Contrae Employment Manager ISend this coupon to tor....$4,000 to $10,000 LI $3,000 to $8,000 Associated Engineers of America Automobile Expert El Plumbing & Heating Electrical $2,500 to $6,500 Expert $4,000to $7,600 537 Dearborn St., Chicago. LI IDept. 344, S. Ill. Business Manager Lawyer Without obligation, send me your 64 -page illustra - $3,000 to $10,000 $5,000 to $15,000 Ited book on Electricity, together with full details of I 13 Accountant or Auditor Shop Superintendent your remarkable plan of home training and member- $2,500 to $6,000 $3,000 to $7,000 ship in the A. E. E. Draftsman or De- Steam Engineer A vacuum tube protector can be made by assembling a Li signer $2,500 to $6,000 $3,000 to $5,000 Name.-_ socket in a standard vacuum tube socket as miniature Electrical Expert Tel. & Telephone Ex - shown above. After you hook up a set, place the test $4,000 to $10,000 pert...$2,500 to $5,000 IAddress lamp in the vacuum tube socket and turn on the rheostat. If the bulb lights, the filament circuit is all right. If the American Technical Society bulb does not light or burns out, there is a wrong connection. Dept.P.425- -Drexel Ave. and 58th St.,Chlcago L'Y -L. W. Orear. 1277 Science and Invention for .1 pril, 1924

NOVEL BINDING POST A seven days wonder in 1903, but al- -eady outgrown in 1909-so rapid is the march of electrical development.

Many amateurs construct binding posts of battery nuts and bolts. From these same parts a post can be made as shown above, the nut of which cannot be lost. -A. Gilbert Billin. A monument to courage MICROMETER ADJUSTER This machine is a Curtis VARIABLE DIAL Steam Turbine Generator. CONDENSER Many called it a "piece of folly" in 1903. It was the largest turbine generator ever built up to that time. The total capacity of the steam turbine Electric Com- generators produced Today General by the General Elec- tric Company is equal pany builds steam turbine to the working power as big of 170 million men. generators ten times More and more the hard tasks of life are as this pioneer; and the "piece being transferred from human shoul- of folly" is preserved as a ders to the iron shoulders of machines. monument to courage.

GJENJERAL ELECTRIC BRASS LEVER

"-THERE'S .PIONEYIN/T" TELEGRAPHI(oM -TOME-__MORSE' AND WIRELESS=--_ in half usual time, at trifling cost, with the wonder- TEACH YOURSELF ful Automatic Transmitter THE OMNIGRAPH. Sends unlimited Morse or Continental messages, at any speed, just as an expert operator would. Adopted by U. S. Govenment and leading Universities, Colleges and Telegraph Schools. 3 styles. $14 to $30. Catalog free. SPRIIVÿ If you own a Radio Phone Set and don't know the Code, you CAM are missing most of the fun. TOP VIEW WITHOUT SIDE OMNIGRAPH MFG. CO. 22 Hudson St., NEW YORK KNOB OR DIAL VIEW

Expert Draftsmen earn from $60 to Send To -day for the be made by following $160 a week and are in line for pro- An extremely efficient vernier can motionotion to executive nions. you can the drawing shown above. An arm of fairly heavy brass Learn become an expert by the Chicago: Tech "Electrical Worker's Friend" slotted at one end. A hole is also Method. Train by mail in .pare time and is first obtained and yourself in the high salaried class. An electrical book of 66 motor draw- provided far the shaft and an adjusting screw placed so put ings with complete instructions for re- $3.00 that the friction on the shaft can be varied. A cam is Drafting FREE TRIAL LESSON winding and reconnecting A. C. motors Send for Free Leeson which abeam how arranged at the lower end so as to move the arm, and Increase Special at therefore the shaft, through a very small space. The coat and on easy torme. Writetotodaytle Or write for full particulars cf this valuable book. Your CO. shaft should not be so great as to prevent COLLEGE SMITH & SMITH PUBLISHING friction on the CHICAGOTECHNICAL Dept. B., 7428 Hermitage St., Pittsburgh. Pa. the turning of the shaft by means of the dial. Income 445 Chicago "Tech" Bldg.. Chleaee. Ill. -Leo Chaviano. 1278 Science and Invention for April, 1924

ROTOR CONTROL

CAMERA If You On FREE Trial! Own a Only 10,000of these marvelous, instantaneous Picture -taking and making cameras to be sent out absolutely on approval without a True SAXOPHONE penny in advance 3ust to prove that it is the Tone most wonderful invention-the camera sen- Here is the great jay sation of the age. so you must send for it maker of all musical in- quick! struments. Unequalled In Just think beauty of tone; the favor- of it-the new ite instrument in band or Mandel -ette orchestra or for home. school, church or lodge entertainment. TAKES AND

In one hour you can play the scale-in a few MAKES weeks play popular tunes and in 90 days take your place in band or orchestra. You may order any Buescher Saxophone, Cornet, Trumpet, Trombone, Finished etc., without paying in advance and try it six days in your own home. If satisfied, you can pay for it on any of our terms to suit your convenience. Write today, mentioning the instrument you Pictures are interested in and we will send you at once Free Catalog and illustrated literature. Buescher Band Instrument Co. Instantly Everything in Band and Orchestra Instruments Ton press the button, drop card In developerand in one 6049 Buescher Block Elkhart, Ind, minute take out a perfect,tinished post card photo 234x334 Inches in size. Camera itself, is about 43ix6x7'inches. f Loads in daylight 16 to 60 post cards at one time. Buescher Band Instrument Co. No Films-No 6049 Buescher Block, Elkhart, Ind. Plates-No Dark Room Gentlemen: Not a bit of the muse and bother of the ordinary kodak Very often it is desired to mount the rotor of a vario or camera. is 1 am interested in the instrument checked helase: It instantaneous photography. Universal coupler so that the hand of the operator will not come SasuVhune....Cornet.... Trombone.....?uutpet fetus lens produces sharp pictures at all distances. near it when adjusting Pictures develop and print automatically. Can't over. the instrument. This can very (Mention any other instrument interested in) develop; results simply amazing. readily be accomplished by following the suggestion illustrated above. The rotor is mounted on a shaft and Name on the center of the shaft is placed a clamp with an ex. Street Address We Trust You tending arm. This arm is then connected by means No difference who you are, where you live of a Town or what fibre link to another clamp on the shaft situated some State your age, we will send you the complete "Mandel -ette' u. outfit absolutely on approval and give you 10 days to teat distance from the rotor. The extension arm on the latter it. If not satisfactory return it. But when you see what shaft should be at the extreme end elegant ppictures of it, so as to allow it takes-so quick,soeasy,with no trouble the knob to rotate through one-half of circle. at all-if you wish to keep it you simply send us 00e per week until our special price of only $10.00 is paid. -Harry Ackerson. Easy Payments-No References No red tape of any kind. Weekly payments so small you'll not notice them. Lots of fun and big profits. Send On the Wrinkles No Experience Required Come on fellows-and young ladies too Plain instructions and everything complete with outfit for that matter-send in your Radio eo you can begin taking pictures the moment it arrives. Wrinkles, but first let us caution We guarantee that even a child can operate it. Mail you coupon right now. No risk or obligation to keep camera. against one thing. That is, try to get away The Chicago from the multitudinous verniers. It seems Ferrotype that in every mail, 90 per cent of the 1 2309 W. Erl. St.. Desk 129 Chicago. Ill. 1 Send me at once one complete model Mandel-ette RADIO WRINKLE entries are some type Camera outfit including supply of post cards and in- of vernier. structions. I agree to examine and test it thoroughly Iand if satisfied keep it and pay you 60e a week until your special price of $10.00 is paid. Otherwise I will return it at the end of 10 days. DIAL STOP i ( Name. St. and No. LLowo State Courtesy of Leslie's Copyrighted O $1400 to $3000 Year , o Men, Boye, 18 or over, Become MAIL Railway Mail Clerks- ,4' COUPON City Mail Carriers- # BELOW Unconditional Post Office Clerks Franklin Institute 2 -Year Travel Guarantee on Gov't o" Dept. H-182, Rochester, N. Y. see your ,w éóunet This coupon, tilled out as directed, # entitles you to (1) free specimen ex - SILVER -S ' Questions: (2) a free copy of .14 CI' our book, "Government Positions and How to Get Them; (3) free list of positions now BATTERY mote obtainable. with genuine AHLBELL NEVERLEAK solid case Half price on this non-leakable Guaranteed Superior Quality COUPON Storage Battery. One-piece indestructible case can't leak, .... Railway Mail Clerk ($1600 to $2300) rot, spill or injure rugs or clothing. Read these prices. ..Income Tax Auditor ($2040 to $3000) 5% Discount for Cash in Full with Order .... Post Office Clerk ($1400 to $1800) AUTO PRICES RADIO PRICES .City Mail Carrier ($1400 to $1800) 6-V, 11 Plate, . $13.00 6-V, 100 Amps. . $13.60 .... Rural Mail Carrier ($1800 to $2600) 6-V,13 Plate, . 10.00 6-V. 120 Amps. . 15.50 Customs Positions 12-V. 7 Plate. . 18.00 6-V. 140 Amps. . 17.00 .... ($1100 to $2000) Read our 2 year unconditional Guarantee before you pay s cent. Bat- Name terd approvai. Send carne áán.á endet,ln wasted TODAY your Address SILVERS BATTERY CO., 201 E. Ontario St., Dept.54 Chicago Use it before you lose it. Write plainly Beautiful Raceabout Instead of Your OLD FORD Choice of Four When celluloid dials are used on radio instruments, it i LATHES Colore; Fiat or the a very simple matter to provide them with stops so tha Ballet Nose Rad- the rotating element of the instrument can only be turned 9 to 18 -inch Swing iator Shell. Send to 180 degrees. First, cut a semi -circular slot in the List price $ 135.00 and up, for 1924 Free Cat- dial as shown above, %g inch wide. A pin of any type according to size. When alog of New Auto whatsoever is then mounted on the panel in such a ready to buy, send for Acces',Bodiesand position that it will be in the slot of the dial. When Lathe Catalog and prices. "'"" " Speed Equipment. Direct from Factory. the dial is placed on the shaft of the instrument and fastened with the set screw it will be found that an W. F. & John Barnes Co AMERICAN TOP Street, DELPHI, IND. AND BODY CO., Ohio efficient dial stop arrangement will 1esult. 442 Ruby Street -Belgrave F. Gostin, ROCKFORD, ILLINOIS Science and In7'enHon for April, 1924 1279

BANJO LOUD TALKER

A "The Loveliest Thing I've Ever Heard

BRL%CKET Over the Radio"-Mary Garden free from D/APHRAM Only the most flawless reproduction, SOLDER distortion and parasitic noises, could earn a tribute so unreserved from America's queen of song. ##/4 BARE The exquisite tone quality and purity of Duo - COPPER WIRE Reflex reception that appealed so irresistibly to B /%z "LONG Miss Garden is finding equally enthusiastic appre- ciation in the homes of super -critical radio lovers An excellent loud talker which d:es not make use of a everywhere. horn of any type whatsoever can be made by pressing into service an old banjo whose head is intact, and some type Not only in sheer tonal perfection, but in range of good phone. A piece of bare copper wire is soldered to the diaphragm of the receiver as shown at B in the and volume, have Erla Duo -Reflex receivers illustration above. This may be done experimentally as demonstrated decisive superiority. Tube for tube, shown in the photograph. Some sort of a bracket such as increased range andvolume, suggested at A in the drawing may be employed to hold as well as elimination of dis- they are the most powerful receivers known. the phone in position permanently. -Clyde J. Fitch. tortion, follow installation of Er la transformers. Re- syn- flex and Cascade types, $5 Complete Erla parts, including celebrated chronizing radio and audio transformers that ANTI -CAPACITY ROD enable vacuum tubes to do triple duty, guarantee success to the amateur who `rolls his own." Easily understood blueprints guide every step of construction and assembly. Ask your dealer for free Erla bulletin No. 20, giving latest Erla one, two and three -tube diagrams; or write direct, mentioning your dealer's name.

Exclusive ability of Erla Electrical Research Laboratoiies audio transformers to amplify three stages without dis- Dept. S 2515 Michigan Ave., Chicago tortion assures improvement in any receiving set. List, $5 Dealers and Jobbers-Erla products turn over rapidly, reducing capital invested and increasingprofit. Send for liberal scae of discounts

New ., 11.t' 110 volt, guaranteed motors, 60 cycle SEND NO MONEYS A.C. Complete with cord plug and pulley. SUPER 32 POLICE Gen. Elec. 1725 speed $16.00 AUTOMATIC Gen. Elec. % H.P. I5 -shot sayer automa. Rep. Ind. $39.00 like those used by Master % H.P tie Rep. Ind. $52.50 German military offi- . H.P. Rep. cers. Extra magazine free. Never One Year Guarantee Master before this was any 15 -shot. 32 -Cal. Auto- Ind. 60.00 matic offered at this price. .$8.95 Master 1% H.P. Rep. Ind. 66.00 Latest Model 9 -shot, 25 Cal. Mauser Auto- All makes and sizes up to 100 H.P. both new and matic, lies flat in pocket. Special at $ 12.25 rebuilt. Motors bought, repaired, exchanged. Let us 32 -Cal. Mauser $13.25 quote on rosir needs. World's Femous Luger. 30 Cal. 17.25 Satisfaction guaranteed or money refunded. Top Break Revolver. 32 or 38 Cal., Special at 7.95 Illustrated catalog of Motors and Supplies Free. SATISFACTION HYRE ELECTRIC COMPANY GUARANTEED 631 M So. Dearborn St. Chicago, Ill. Send No Money. Pay Postman Our Price, Plus Postage. All Brand -New Guns. Use Standard Ammunition. very close work with Insure your copy reaching you each In tuning in C. W. stations or for POCKET AUTOMATIC almost any type of regenerative set, it is desirable to have aorn nso ua- month. Subscribe to Science and Inven- some arrangement whereby the dials can be turned without 77 adne snmdoao - having the usual body capacity effect. An excellent method tion this 7 -shot, 25 -cal. tion-$2.50 a year. Experimenter Pub- of accomplishing this without defacing the set itself is automatic illustrated above. A two-inch rubber ball is cut in half beat ßnnot $6.75be lishing Co., 53 Park Place, N. Y. C. and mounted on a rod as shown. -Tom Tamen. WATTS TRADING CO. (Contimecd on page 1281) Warren St.. Dept. 653. New York City 1 c' Science and Invention for April, 1924

All Products Advertised in "RADIO NEWS" that bear this stamp of approval have been tested in the "RADIO NEWS" Labora- tories. Watch for the stamp

RADIO

Everything that is worthwhile in the radio industry appears NEWS in "RADIO NEWS." The most popular new circuits are fully "RADIO NEWS" has a cir- described and diagrammatically illustrated. The latest notes culation of over 300,000 which is over 130,000 more from the broadcast stations are commented upon. New radio than any other radio magazine. All the important equipment of every description is displayed together with radio manufacturers adver- reports of novel sets and unusually successful radio hook-ups. tise in "RADIO NEWS." Every important advance in radio broadcast or reception in On All Newsstands on the 10th of the Preceding Month any part of the world is fully written up. In a word "RADIO NEWS" covers everything big, active and worthwhile in the 25c THE COPY or radio field. by the year, $2.50. If you wish to subscribe use the coupon for convenience.

Experimenter Publishing Co., S.I.-4.24 53 Park Place, New York Experimenter Publishing Co., Inc. Enclosed find dollars for which please enter my subscription to RADIO NEWS Publishers of for years. Radio News, Science and Invention and Practical Electrics 53 Park Place, New York City, N. Y. Name Address Science and Invention for April, 1924 1281

",,,,n,,...,,,,,,un ,,,,,,,,,,,,umu,,,unnunmunnumunl,,,to,u,,,,,,,,,nuunnnwIlmmumm,,,,,,,,,,a Radio W£c'Ilnkles (Continued ronp1279 ml,ru.,,1111111 , n t ol, ,, ,, ,,,,,,,: PHONOGRAPH ATTACHMENT WL?JonWas $ 700 and $ 8.00 SHOES any at$5o46 ---93oys'at$4.50& 5 loud speak/ng phone., W. L. Douglas name and portrait is the best known shoe trade -mark in the world. It stands for a high standard of quality and dependable value. For economy and Tapered ti» tube that Stamping the retail satisfactory service wear shoes soldered ta /id's. price at the bear this trade -mark. factory

W.L.Douglas' ORFL for Women Campus Made of a fine grade of Brown Kid, also A bright tan Russia Calf Oxford for Men Black Kid, in Blucher Oxford pattern. on a wide brogue last. New, attractive A very neat model of the corrective type pattern with black stitching and eyelets. with splendid fitting qualities. The corset Patent Leather Cork Welt and trimming Phonograph effect gives -COMFORT and SUPPORT around top; rolled heel. A smart. up-to- Tone arm to the. ARCH. Exceptional service at a the-minute style for Spring and a won- price,ice, $7.00. derful value. $8.00. W. L. DOUGLAS name and the retail price are stamped on the sóles of every pair at the factory. The value is guaranteed and the wearer protected against unreasonable prices. The above illustrated phonograph attachment for using he born of the phonograph, while very simple to build shoes are demanded by more people than any s quite efficient. First, cut the size and cut to the W. L. DOUGLAS orrect length the top and bottom of a tin can. Con other shoes in this country. They are put into all of our 116 stores truct a slightly taoered tin tube and solder to the lid of the tin can having made a large hole directly under at factory cost. We do not make one cent of profit until the shoes where the tube is soldered. Connect the tapered tin are sold to you. It is worth dollars for you to know that when tube to the phonograph tone arm by means of a card boars or rubber tube, from which the reproducer has been you buy shoes at our stores You Pay Only One Profit. removed. -D. J. Oyer. NEVER have you had the opportunity to buy such wonderful VARIABLE CONDENSER shoe values as you will find inW. L. Douglas $7.00 and $8.00 shoes in cities in good shoe MOVABLE PLATE in our retail stores the principal and stores BASE everywhere. If you do not live near one of our stores, ask your 3Y2" ' MICA shoe dealer for W. L. Douglas shoes. I f he cannot supply you, write for catalog showing how to order shoes by mail, postage free. ,4,-----STATION ARY W. L. DOUGLAS SHOE COMPANY PLATE. 137 Spark Street, Brockton, Mass.

Useful and En nine Big 3 -Ft. Telescope (In Wive Sections) See people and objects miles away, on land or sea, an if they were close. Wonder TAPE Telescope gives new pleasures to home, farm, camp, travel, sport. See moon and Stars as never before. Opens out over 3 feet long; measures 12 inches closed. Brass bound; has powerful lenses. Th pleased -"Could tell color o aeroplane 4 miles away."-Mrs. Yarbrough. "Saw Provincetown Light, 28 miles away, as clear as if in front of me."-Clyde Scribner. ` IAL

. 'la While they last "1 have been watching submarines s miles Because of a fortunate purchase fawn a large repeal' o8 the coast."-P. Grush. "Can see children playing in hool yard 6 manufacturer we can give you a big bargain. Be first in your miles neighborhood; entertain your friends. Send no money; send n. 'Renumbers'Hd the on - only name and address for telescope complete by parcel poet. On arrival freight care mile away, deposit with Postman only $1.35 plus a few pennies postage. Satisfaction see mountain, on or money refunded. moon."-A, C. guaranteed Order today while the supply lasts. Palmer. FERRY & CO.. 75 W. Van Barren St. Dent. Chicago. R4 HOLE FOR. 1254 MACHINE SCRE ONE THOUSAND AGENTS WANTED want one thousand agents to sell subscriptions to RADIO WENEWS, SCIENCE AND INVENTION and PRACTICAL ELECTRICS. We will pay a generous commission for this work and help you in every way. Our three publications are leaders in their fields, ready sellers and this is an offer well worth your while. A few spare hours a day will bring you a handsome return. Write regarding our_proposition at once and be the first one to get started in your vicihit : A simple experimental variable condenser may be constructed as shown above. Cut one movable plate and one stationary plate as shown. Mount the latter on a EXPERIMENTER PUBLISHING CO. base and cover with mica. Mount the stationary plate HERBERT H. FOSTER, Sales Manager as shown and wind the end of the handle with tape for 53 Park Place New York insulation. -Herbert T. White. 1..,1e_ Science and Invention for April, 192-1

VARIOMETER CONTROL How to Become a Marvel of Muscular Development

..i 8 IÍO/C

You Can Develop Enormous Muscles With This Newest and Greatest Invention in Physical Culture Apparatus If you want to be a real strong man, if you want to build j6 S0//l/ self ..... up a powerful, muscular body that will make you stand ui among men, you can do it simply by using the McFadden Patented 10 Cable Progressive Exerciser. which .an be instantly converted into two 5 cable progressive exer- ¡ cisers. t'an be adjusted to give you as much resistance l/arN°1 1,5; as you want up to 200 pounds. NEWLY PATENTED STIRRUP i This ingenious device is a new addition to the McFadden 10 Cable Progressive Exerciser and is provided to give you the proper exercise to build up the most Powerful loge. ADJUSTABLE PATENTED HEADGEAR increases the size of your neck $50 Raise !" one inch in 30 to 90 days This apparatus is simplicity itself and with it you cas "Why, that's the third increase I've had accomplish the sisal wonderful results. It is adjustable N°? vAriamrtPr and will fit any man or boy. By using it in Connection a It shows what special training N'. t'ociarnter in year! %ntro/''-_, with my Progressive Exerciser there is no reason why you will do for a man." Contra/ cannot become just as strong as you want to be. Every mail brings letters from some of 12 Weeks Home Instruction Course FREE the thousands of students of the Inter- he 2 N'1 The introductory price of the whole outfit is only $8, a Schools, telling of Brass or fDre very small cost for what it includes. If you are not fully national Correspondence satisfied your money will be refunded without quibble or advancements won through spare -time study. 9Pars question. Send NOW for this great outfit. Delays do not make strength. Order TODAY. How much longer are you going to wait before taking the step that is bound to bring Michael McFadden NEW 2'103YOR K I CITY you more money? Isn't it better to start now than to wait for years and then realize what the delay has cost you? - - -Dia/ far var FOR THESE supper each night spent with the One hour after ---107,26 íör !%c A/22 AUTOM T CS I. C. S. in your own home will prepare you for the SEND NO HONEY position you want. Without cost, without obligation, F/9, Lowest Prices in mark and mail this coupon. Do it right nowt N'2. 2 N21 the Country INTERNATIONAL CORRESPONDENCE SCHOOLS 20 SHOT Box 6231-C, Scranton, Penna. MILIrL - Without cost or obligation on my part, please tell me 32 cal. withith Extra 45 how I can quality for the position or in the subject before Magazine FREE which have marked an X: 84 I 25 Cal. 6 -Shot BLUE STEEL..$6.65 BUSINESS TRAINING COURSES 25 Cal. 8 -Shot MAUSER ....11.50 Business Management Salesmanship Industrial Management Advertising LyUNDfR Bert 6radeaede Personnel Organization Better Letters SWINGS 6 SHOT Traffic Management D Show Card Lettering OUT NANO EJECTOR Business Law D Stenography and Trping A 32)0 Banking and Banking Law Business English 32 Ca11545 NZ' $ i645 ['Accountancy (including C.P.A.) Civil Service Cal - ONicholson Cost Accounting Railway Mail Clerk Bookkeeping Common School Subjects 32 or3B Cal.R High School Subjects 6 Private Secretary Break Open".V-7e al Spanish French ]llustrating 5h 00 lit the standard two variometer REVOLVER Mandfjertor TECHNICAL AND INDUSTRIAL COURSES sets the controls for the wo variometers take up quite a lot of space. Two Electrical Engineering Architect methods 32,32 m° DElectric Lighting Blue Print Reading are suggested above for conserving space. In no 38 Cal gMechanical Engineer Contractor and Builder Fig. 1 is shown the two variometers mounted directly back Mechanical Draftsman Architectural Draftsman of each other with a double knob and dial for control. Machine Shop Practice Concrete Builder The LUGER Reduced Structural Engineer same type of control is used in Fig. 2, wherein the I $1225 Railroad Positions variometers are placed side by side and the large knob ccum.+r Brand Ne w Guns Gas Engine Operating Chemistry Pharmacy GEAMANs2s Civil Engineer 9Automobile Work geared to variometer No. 1. -Harry Ackerson. 30 Cal. ow. Use Standard Surveying and Mapping Airplane Engines 9 SHOT Ammunition Metallurgy Mining Agriculture and Poultry Satisfaction Guaranteed or Money Refunded Steam Engineering Radio Mathematics Par Postanan Ou. Price Plus Post a çe Name EDWARDS IMPORT TRADING CORP. Street 11-a.-23 LOOP AERIAL MOUNTING 258 BROADWAY Dept 943 NEW YORK CITY Address City State Occupation (INSULATINC1 Persons residing in Canada should send this coupon to the ROD SUPPORTING International Correspondence Schools Canadian, Limited, Montreal, Canada LOOP AERIAL SEX Facts other sex books don't dare discuss are plainly told in Try This on Your "Where Knowledge Means Hap- piness." Creates a nett I; Ind of married love. One reader says: Hair 15Days It contains more real in- Then let your mirror prove results. formation than all other sex Write FREE Trial, nferd hooks gut together. need not From "Where Knows- 4 you become bald, for there ie a way PIPE Sent in plain cover, by re - to destroy the microbe that destroys the hair. Thie differ- edge Ricans Happiness" turn mail, for $1.00, cash, ent method will stop thinning out of the hair, lifeless hair Copyright 1921 money order check or stamps remove dandruff, itching, darken gray hair and threatened or increasing baldness, by strengthening and prolonging Dept.39 COUNSEL SERVICE,257 W.71 St.,N.Y. life of the hair for men and women. Send your name now before it is too late for the 15 days' free trial offer. M-461 Chicago You can be quickly cured, if you AYMESCO.,3932N.RobeySt., FLOOR. FLANO AUTOMOBILE MAKES 27 MILES ON AIR STAMMER Send 10 cents fer 288 -page book An automobile goes 27 miles on air by using an Stuttering, on Stammering ami BASE "Its Cause and Cure." It tells how I automatic device which was installed in less than cured myself after stammering 20 yrs. B. N. Bogue, 8103 Bogue 5 minutes. The automobile was only making 30 Bldg., 1147 N. III. St., Indianapolis. miles on a gallon of gasoline, but after this remarkable invention was installed, it made better " BECOME A LIGHTNING An excellent stand for a loop aerial may be made from 964- than 57. The inventor, Mr. J. A. Stransky, 638 an 8 or 10 inch length of 1 or 11/2 inch pipe screwed TRICK CARTOONIST" Eleventh St., Pukwana, South Dakota, wants into a standard floor flange. The insulating rod support- Make money chalk talking. Send $1 for snappy program of trick drawings. with instructions by a agents and is willing to send a sample at Isis own ing the loop aerial is to be placed in the pine and can professional cartoonist. Satisfaction guaranteed. risk. Write him today -Adv. he rotated at will. -Charles Mallinckrodt. Circular free. Balda Art Service. Dept. 4, Oshkosh. Wig. Science and Indention for April, 1924 1283

,,,,11111,,,,Ill,,,,,,,,J,,,1s111,111111,1,,,,,,, ,,,,,,,,.11,11111111111111,,,,,,,, T. Na1ckerasawDs Secrets By CLEMENT FEZANDI$ (Continued from page 1205) 1111111111M11111,.,111111111111,,,,111111111111,,,,.1,,,,,,,,,,,,,.,,,,1,,,11,111111,1111111,.11111111111011,,,,,1 RADIO! step into my airplane, and in less than half an hour we shall be at my Jersey farm, and -uen. ..ma RPCErvES there, in five minutes, you will get a better YPP. iP{ idea of my giants and dwarfs than you would from whole volumes of talk." The menagerie was indeed an interesting place. Some thirty miles from New York City, Doctor Hackensáw had started a Brobdingnagian farm. Trees but a few years old were there, yet they towered higher than the gigantic California redwood trees. The grass of the pasturage was the height of ordinary corn. Giant animals and plants of many varieties were present, and there were numerous outlandish -looking species which the reporter did not recognize, they Down Puts This Famous being enlargements of insects and of micro- scopic animalcules. Here, too, was an aquarium with sardines as large as salmon, and salmon as large as small whales ; while, on the other hand, a diminutive sperm whale was about the size TUSKA of a minnow. MICROBES Armstrong Regenerative 3 -Tube Outfit "What in the world are those?" asked Silas, pointing to a row of tanks in which in Your Home certain nondescript species were floating in in Easy Monthly a peculiar liquid. Balance Payments Doctor Hackensaw chuckled. "Those are With this great offer the finest of radio equipment becomes available to every home. Why my pets !" said he. "Those are giant bacteria tinker with home made sets! Why confine your radio reception to the few local stations and bacilli. I have here the disease-germs reached by a crystal set! For only $5 down you can have a radio set that will reach out of cholera, malaria, yellow -fever and of hundreds-even thousands of miles away and "bring in" your choice of all the wonderful many other illnesses. By growing them to programs broadcasted from the Atlantic to the Pacific. It has ample volume to operate a this gigantic size, I can study them much loud speaker on far distant stations. In the TUSKA we offer a set designed by Mr. C. D. better than I could through a microscope, Tuska-a famous radio engineer-and built complete under his personal supervision. In and learn their life history and the effects results-in appearance-in workmanship-it is equal to outfits costing twice the price of remedial agencies. Many a fact have we ask. Send coupon below for our Great Special Offer made for a limited time only. I learned that will be of the greatest use in medicine, as well as in the arts; for you must know that microbes play a most important rôle in the industrial arts :-in fact, life itself would not be possible without them. Outfit Complete I am gradually accumulating giant specimens of the most important species, and I No accessories to Buy confidently expect to revolutionize many I The radio outfits we sell are absolutely complete. Most others make an oiler on the bare set and leave branches of science by the knowledge thus you to buy all the extras like tubes, phones, etc., in addition. The outfit we offer you includes the gain. Regenerative Receiver and 2 -step amplifier all enclosed in a solid mahogany case. Also the batteries, "Then too, since each part of the animal head -phones, tubes, aerial, lightning arrester, and full wiring installation equipment. Start operating without investing another penny. Your $5 payment brings it all. The use of UV -199 Tubes reduces is increased in proper proportion, I am en- upkeep to almost nothing. These tubes use only .06 ampere current, assuring long life to your batteries. abled to study the anatomy of the various organs, the red blood corpuscles and the IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII phagocytes that attack the disease germs; the Marshall Radio Products, Inc. various tissues, the glands and their secre- Send Coupon 2843 W.19th St., Dept.53-34Chicago,Ill. tions ; and the poisons and antitoxins and For Great Special Offer Please send me your special offer on a Com- the serums I can likewise study the changes lust mail the coupon. Get all the details without plete Tuska Radio Outfit on terms of $5 down produced by disease-in short an entirely any obligation. Don't think of buying an ordinary and monthly payments. new world is opened up to scientific investi- set without finding all about this new and better way. Very easy terms. Free trial. The highest gation." quality of radio equipment possible to have. Name "How about your dwarfs?" - Marshall Radio Products, Inc. "They are not so useful, and I have made 2843 W.19th St., Dept.53-34Chicago, Ill. comparatively few of them. That four- Address ... -- year -old baby giant you see over there, is looking at his twin brother-a four -year -old dwarf held in the palm of its nurse's hand. Yet both were grown from the same egg. I Quite a contrast between the two, isn't there Made $ 100,000 EARN MONET first child fifteen feet high and his in less than five years as a real estate specialist. -the during my spare time, with no experi- AT HOME twin brother about five inches in height! Started ence, and less than $5 capital. If you want to VOU can make $15 to $60 weekly in your spare If I had made him a little smaller I could learn the secret of my success and follow my time writing show cards. No canvassing carry him around in my pocket and pass him moneymaking method, send your name and or soliciting. We instruct you by our new through a keyhole whenever I wanted to address at once to American Business Builders. simple Directograph System, supply you with Dept. 41, 1133 Broadway, New York. They work and pay you cash each week. Write know what was in a locked room. He would today for full particulars and free booklet. of send full information free, telling you how be an invaluable assistant for a gang you can build up an independent, profitable WEST-ANGUS SHOW CARD SERVICE LIMITED criminals. Behind him you will see a hull - Authorized Capital $1,250,000.00 business of your own by using my amazingly 67 Colborne Building, Toronto, Can. moose, small enough to fit into a coffee-cup, successful system. but just as savage as if he were full size. See how he comes butting at my shoe !" And with the words, the doctor stooped down and picked up the frantic animal in his hand, and Insure your copy reaching you each month. Subscribe to Science and Inven- exhibited it, kicking and struggling, before tion-$2.50 a year. Experimenter Publishing Co., 53 Park Place, N. Y. C. he set it down again. 1284 Science and Invention for April, 1924 A DREAM "Last night, Silas," continued the doctor. 0 "I had a most peculiar dream. I dreamt P05 that I had succeeded in making a human AGENTS ROFIT midget, the size of a microbe. I had a hard job teaching him to speak, but managed Genuine Gold Leaf Letters it in this way. He spoke to me through a GUARANTEED TO NEVER TARNISH loud talker, while I answered him through For store fronts, office win. a special instrument I invented to reduce dowa, Bank windows. Office Doors, Panels, Board Signs. sounds. Then I encased him in a micro- Trucks. Automobiles a n d FREE TRIAL scopic Glass Signs of all kinds. submarine and injected him into the Anyone can put them on and blood of a rabbit, with instructions make money right from the to ob- start without ehoose YourG'onn serve and report to me all previous ex- that he saw on perience. All you have to his trip. course, do is to show your samples: Of in his submarine, he the lettera are very attrac- ?nstrument could pass unharmed through the circula- tive and easy to sell. Let- ters costing 4c sell for EASY PAYMENTS tion and visit the different organs of the 25c. One agent says: "Your body in turn. I especially wished him Letters are the best thing I to have seen in years: I have made $1.25.00 the first study the digestion and the action of disease peek and still going strong." Paul Clark says: ''smallest day $28.70." H. Gilder made $835.00 in germs and the anti -bodies. I followed his six weeks. course by means of an X-ray apparatus, and after a week's trip I removed him from $60 TO $200 A WEEK the rabbit's body and was gloating in antici- GENERAL AGENTS-It is easy to appoint euh -agents for this line. We pay you 20% pation over the wonderful account I was cash commission on all orders we receive from local about to receive, when I was awakened by agents appointed by you anywhere. we allow you 50% are discount on your own orders. You can sell to nearby Conn instruments the yowling of a cat on the back fence! trade or travel all over the country, as you please. used and endorsed by the Wouldn't that you!" Large demand for window lettering everywhere. write jar today for free sample, full particulars and liberal offer world's great artists - in to general agents. bands and orchestras. * * * * * Exclusive features make The day following the one on which the METALLIC LETTER CO. them above conversation took place, the New 415 N. CLARK ST. CHICAGO - easiest to play York Daily Growl appeared with the follow- -beautiful in tone ing glaring headlines: -perfect in scale Menagerie of Giant Beasts Let Loose! Army -most reliable in ac- Escape of Doctor Hackensaw's Gigantic Standard of Spanish tion -slide, valve or Animals. Cow, the Size of a Brontosau- Genuine Astra key rus Running Wild in Harlem! - handsome in design The fact of the matter was that the giant $7 .7$ Conn is the only maker of every instrument cow had broken loose and had butted down used in the band. the wall of the enclosure; and giant rab- Adopted by bits, chickens, dogs and what not, had made French During Hydraulic expansion of tubing, Conn's World War original patented process, insures perfect their escape and were terrifying women and children in the suburbs. The finest European pistol- proportions-as smooth -as -glass carriage for Drop Forged Blue Steel Throughout- uses sound waves. Men with shot -guns and pitch -forks chased standard ammunition, an accurate, hard-hitting, the intruders, and the police, too, brand-new weapon. Profit and pleasure for you with a Conn. took a Bought before recent tariff raise. Buy now hand. But it was not till a regiment of from sole U. S. importers and save abouth on Play the instrument of the soldiers organized a systematic hunt for the these fine guns. artists. Insist upon the genu- fugitives, that the last of the giant beasts $7.75 25 cal.. 7 shot ASTRA, C. O. Q. Automatic. ine Conn. was slain. 8.95 25 cal., 7 shot AST RA, Automatic. 9.96 25 cal., 7 shot ASTRA, triple safety. All the exclusive Conn fea- Doctor Hackensaw cheerfully paid all 10.98 32 cal., 10 shot ASTRA, extra magazine. tures are yours at no greater damages, but he was inconsolable 16.95 32-20 and 38 cal. swing-out cyl. revolvers. at the loss Write for firearms catalogue. We guarantee cost than for ordinary in- of his cherished menagerie, the result of perfect workmanship and material: every gun brand struments. Highest Honors new; of drop forged steel throughout. Before buying many years of patient work. any gun Insist on this guarantee. Send no money at World Expositions. unless you wish. Pay postman on delivery plus post - fully ACT NOW tohgetlthese SPECId ALoLO PRICES. FREE BOOK WRITE TODAY. "Success in Music and How CALIFORNIA TRADING COMPANY to Win It" by John Philip Dept. 25-4, Terminal Bldg., Los Angeles, Cal. Sousa and other famous mu- Cen4TrifugaIl Dnsh Ernest Pechin, sicians. Send coupon now cornet soloist for your copy and details of rSKIN Conway's Band CReaner ii OIl TilR (above) and John Free Trial ; Easy Payments mad(qLLL Dolan cornetsolo- Mention Instrument ist Sousa's Band, PIMPL who endorse C. G. CONN, Ltd. When a few applications of this won- Conns as supreme 456 Conn Bldg., Elkhart, end. der working lotion has cleared faces of pimples, blackheads, rx acne eruptions on the face or body, enlarged pores, oily or shiny skin, you can realize , why CLEAR -TONE has been tested and approved in over 100,000 Test Cases. C The simplicity of the treatment. BAND The Story of How I Cured My- self are all explained in my INSTRUMENTS free booklet. Write for your copy WORLDS LARGEST MANUFACTURERS ay and learn of the results gotten by thousands of men and women. E. S. GIVENS 168 CHEMICAL BLDG. AADSAS CITY, M0.

SEND FOR THE INTERNATIONAL CATALOG Our net price list. Sena! Full line of MA/ auto bodies and accessories for Fords C. G. CONN, Ltd. at Wholesale 456 Conn Building Prices. Save Elkhart, Indiana big money on Please send "Success in Music" bodies by buying Direct from and details of Trial Offer of FOR FORD-Prices from $27.85 p. Factory oory Instrument consumer direct-Pay only One Profit Name International Body Works, 914 WOhio St., Dept.4, Chicago, Ill. St. or Rural Route Wrestling Book FREE By means of a centrifugal basket, operated by a motor Teis how to be it greet athlete d ocien- ...... _.._.._...... __.._.._.._...... __._ uae wrestler - how to WIN Startling secret. and installed in a kitchen sink the daily grind of washing taught In wonderful lessons by Id's ham. County dishes is reduced to merely placing the soiled plates and Farmer Burns strong.ion. healthy athletic. ¡Inedlekbigomes witth cups in the wire basket and starting the motor. A spray Belt defense. Be a lender. Men and throws water on the dishes during the entire washing boy,Learnwrite for Free Book today. State your age. process. W. Von Stein, Reporter No, 126. arato BwoaScbool,l254 Railway Bldg., Omaha, Nob Science and Invention for 1pril, 1924 1285 yumunimwuuwwn11,,,,un,n11111,,,11111111111,1,uuunu,u,uwwnuwuumuununwwuuunwu =

The an On the _ eteor 'How IBecame Popular PART IV By RAY CUMMINGS (Continued from page 1203) _ Overnight!" ,,,,,,,,,,,,,,,, ,,1111111111,1,,,,,,,,,,,,,,,,,,,111,11,11111111.,,,,,,,1,,,,11111,,,,1,,,,111,,,111111111111111,111,,,s "They used to avoid me when I asked III for a dance. Some said they were tired, others had previous engagements. The first of these incidents in Rax came Even the poorest dancers preferred to when Boy was about two months old. A sit against the wall rather than dance Caan's with me. But I didn't 'wake up' until young virgin, the daughter of one of a partner left me standing alone in the workers, disappeared. She was a girl some- middle of the floor. what younger than Nona. She was beauti- Posed by "That night I went hone feeling pretty lonesome and mighty Hope Hamp- ful, in Marinoid fashion. To you, all these blue, As a social success I was a first-class failure. At first ton, Movse that you could teach by mall because I Marinoids must seem grotesque-unhuman I wouldn't believe to Star, a n d always had the Idea that one must go to a dancing class Mur- perhaps. But beauty is not universally stand- learn. But I figured I could risk ten eents-especially since Arthur guaranteed to teach me. ray, the ardized-only locally. We admire our own you World's fore- kind. Your natives of Zanzibar think their Dancing Made Me Popular most dancing How Instructor. own black -skinned, thick -lipped belles the "Being a good dancer has made me popular and sought after. beautiful on Earth. And as I have said I am invited everywhere. No more dull evenings-no bitter most disappointments! My whole life is brighter and happier. And once before, in the Marinoid world the I owe it all to Authur Murray. of "I was astonished to see 00w quickly one learns all of Marinoid women were the standard the latest steps through your diagrams and simple instructions. beauty. Nona, so different, was the excep- I mastered your course in a few evenings, and, believe me. I surely did give the folks around here a big surprise when tion, the abnormality. I got on the floor with the best dancer and went through This who disappeared had been with the dance letter perfect. Now that I have the Murray girl foundation to my dancing I can lead and follow perfectly one of Caan's scattered parties working on and can master any new dance after I have seen a few of the steps. the sea -bottom, gathering shell -food. She "My sister's family have all learned to dance from the had wandered away from the others, and course I bought from you and it would do your heart good to see how fine her little kiddies dance together after when the time came to return to Rax, she quickly learning from your new method of teaching dancing was missing. We thought she might have at home without music or partner." become ill and gone home. Learn Any Dance in a Few Hours enclose 10e (stamps or coin) to pay cost of postage, not at home-nor could she printing, etc., and the lessons will be promptly mailed to But she was Whether you want to learn the For -trot, One Step, you. You will receive: (1) The Secret of Leading. (2) be found anywhere in the city. Even this Waltz or any of the new dances, you won't have any How to Follow Successfully. (3) How to Gain Confidence. trouble in doing it through Arthur Murray's new method. (1) A Fascinating Foz -trot Step. (5 ) A Leeson in Waltz- did not arouse much interest, except to her More than 120,000 people have learned to dance by mall, ing. Don't hesitate. You do not place yourself under any own immediate family. It was thought that and you can learn as easily. obligation by sending for the free lessons. Write today. Arthur Murray is the World's foremost authority on ARTHUR MURRAY, Studio 152, 801 Madison Avenue, some young Marinoid man had taken her nodal dancing. Through his new improved method of New York. According to custom the couple teaching dancing by mail he will give you the same high- for mate. class instruotfon in your own home that he would give might readily have disappeared for a time- you if you took private lessons in his studio and paid his Arthur Murray, Studio 152, gone out together to live in the forest to regular fee of $10 per lesson. 801 Madison Avenue, New York City. To prove that I can learn to dance at home in one escape work until their first period of love Five Dancing Lessons Free evening you may send the FIVE FREE LESSONS. I past. enclose 10e (stamps or coin) to pay for the postage, was SO sure is Arthur Murray that you will be delighted printing, etc. But there seemed no young man un- with his amazingly simple methods of teaching that he has consented for a limited time only to send FIVE Name accounted for-and the girl did not return. FREE LESSONS to all who sign and return the coupon. so, the incident would have been for- These five free lessons are yours to keep-you need not Address Even return them. They are merely to prove that you can but soon another young girl dis- without music or partner in your own home. City State gotten, learn to dance Row, London, England appeared. Write for the five lessons today-they are free. Just Also at 150 Southampton There were perhaps thirty who vanished during that year. They were not all from the workers outside the city. We had long since ceased to take women with us ; and those who lived in the forests and the mud - $1662°Ó Earned óÑ banks carne crowding into Rax-and to the s other cities nearby. We knew very soon, of course, that our A New Business-Big Business Marinoid women were being stolen. And there was one crowning incident that at last A Business to Enthuse Over- made us understand. It was at what you would call midnight, The "Ideal" Lawn Mower Sharpener when the city was asleep. Caan and I, on a A wonderful invention that sharpens lawn mowers scientifi- belated errand, were swimming down one cally-quickly-perfectly; does the work as nothing else can. of the vertical streets. The place was de- W. F. Kendt, Fred C. Milkertof Melrose Park, III.. writes: serted; the street was empty ; the lights at 1476 Main St.. "The Ideal Lawnmower Grinder put me in business, starting in Buffalo, writes: to intervals on the side walls of the houses illu- 1 sharpened 9941awnmow- the basement of my home and forcing me now for the third time mined the water with a green, diffused glow ers last season, and the move into bigger quarters. Today the dream of my life-a shop of receipts were $1662 which my own-is realized.With a machine like yours and a little hustle -like lights in a thick fog at night on your is not bad of his own and be independent." far a side any man can have a business Earth. The windows along the street for line." No town too small.Lawn mowers the most part stood open. Everywhere was You Start Now are dull-owner doesn't know only the swish of the where to get them sharpened. Mowing the lawn dreaded because heavy silence, with of dull or improperly sharpened mower. Lawn mowing healthful. water as Caan and I swam through it. invigorating and pleasant when Mower is 'Ideally" sharpened. A green figure in the horizontal street You do the work scientifically-you are in big demand. below us attracted our attention. It seemed Lawn Mowers Sharpened to Razor Edge- to be a man swathed in a green cloak of People glad-owners delight in mowing lawn with mower sharp- coming, and darting up ened on añ 'Ideal. " Mower runs light seaweed. He saw us -click -click -click and the grass is street light which hung nearby, he , i to the cut. Build a permanent business now! Aj USE THIS-Mail It TODAY flung something over it. for yourself. Start The Fate -Root -Heath Co. light was obliterated; shadows fell s Get our 8D3 Boll St., Dept. 39. Plymouth, Dhla The Write Todayprop.-p po- Please mail at once details of your over everything. s FREE-We have detailed complete proposition. illustrated book to send you. Write today for THE KIDNAPPERS proposition. Name Caan and I were startled; we hung poised, The Fate -Root -Heath -Co. could Address just above the cross -street so that we Dept. 39, 803 Bell St.,Plyinese 0. in There were , see along it both directions. lights at distant corners. We heard a low but penetrating cry from near at hand. A signal ! Other figures in the distance darted 5 Master Keys put out the lights. Work like magic In emergencies or prove up through the water and whether your door or padlocks are burglar- The entire street was in darkness. proof. Oven and test thousands of different I downward, shouting. locks. Racemmended by users in ten dif- Wonderful, new device, guides your hand; corrects Caan and whirled ferent nations. Most wonderful and only your writing in few days. Big improvement in three Through the window of a house, we saw the keys of their kind. Send $1 today. Novel hours. No failures. Complete outline FREE. key chain FREE with set. Write C. J. Ozment, Dept.44 St. Louis, Mo. stiffened body of a woman come floating. MASTER KEY CO., 78 West Water St., Milwaukee. Wig. 1286 Science and Invention for April, 1924 There was light enough for us to see her white face and arms-a woman unconscious, You Can Be A shocked into insensibility as we, later learned, by a bolt of animal electricity from her abductor. Her body floated from the window as General Manager though pushed from behind. In the darkness, green -swathed forms seized it-forms which were barely discernible as blurs in the dark water-seized it and began rapidly tow- ing it away. Caan and I were after them. Our cries were arousing the city. Voices-confused questions-came from within the houses. Figures appeared; the street behind us was Beat 'em all in a turmoil. The woman's body with its almost invisible with Auto -Wheel assailants was moving forward rapidly. You can beat 'em all, race or no race, if you are Lines of white as the highly aerated water "driving" an Auto -Wheel the speediest boys' coaster. Winning is dead -easy. Only another was stirred, radiated out V-shaped from its Auto -Wheel can give you any competition. rapid progress. It's the self-contained, friction -reducing - roller But Caan and I, unburdened, could swim bearings which make an Auto -Wheel Coaster go so easily that it seems to be running itself. But the faster. We overtook the invaders. There roller bearings are only one of the many superior was a struggle in the darkness. A bolt of features in the electricity went through me, but I recovered from it. Caan was shouting in hot anger as he struck at the green shapes that were at- utaMteel Wallace Rohrschneider tacking him. Write for catalog of all models of the Auto - The water all about us was lashed into Wheel and the Auto -Cart (for little brother or became General Manager of the Hustisford (Wisconsin) sister). If you send names and addresses of three Electric Light and Power Company at 28 years of age. He white. It caught and reflected the light from coaster wagon dealers in your town, telling which took his training and got his start at the School of Engi- a suddenly illumined window hand. neering of Milwaukee, und advanced rapidly to Ide present near at cell Auto -Wheel, we give you a year's subscrip- splendid position. I found myself gripping Og! tion FREE to the "Auto -Wheel Spokes -man," "You !" our magazine. Why Don't You Get Into But my voice seemed to inspire him to Auto -Wheel Coaster Co., Inc. frenzied effort. He jerked away from me- North Tonawanda, N. Y. This Big Pay Field? was gone into the shadows. The same kind of training that put Mr. Rohrsclmefder Caan was now shouting triumphantly. He into the ranks of the highly -paid Electrical Specialists will had dispersed his adversaries. The woman's qualify you for brilliant success in this fascinating field of unlimited opportunities. Come to America's Greatest In- white body-neglected-had sunk to the floor stitution of Electrical Education. Leann by actual practice of the street. We swam down her, chafed in our big laboratories with their magnificent equipment. to including motors, dynamos, switchboards, ignition and her arms and neck until at last she recovered SEND lighting systems, etc. Recognized experts give you personal instruction every step of the way. consciousness. The street was relighted. The houses were J NO emptying themselves of their frightened Earn Your Way Through inmates. A crowd gathered around us with This Great College confused startled questioning. MONEY But Og and all his cohorts had escaped. 5 DAYS FREE TRIAL You can earn money to help defray your expenses while you are learning. Our An hour later, when I returned home, Boy INVINCIBLE"Rebuilt GUARANTEED wonderful co-operative plan brings an STANDARD No.10 Self Electrical Career within the reach of every ambitious man. was lying in the hollow white shell which StaderNodel REIN I NCTON .W Our Free Employment Department secures positions for those students who wish to earn part or all of their expenses. In was his cradle, crying lustily. And Nona- addition, the Department will help you get a good position my Nona-was gone! A real bargain. All late Improvements -84 char- in the Electrical industry when your training is completed. acters, standard type, back spacer, etc. As near BIG BOOK FREE-Mail the coupon today for our big new Illustrated catalog. Check the course that interests you IV new in appearance and operation as modern most and we will send you special information. Read about the School that trains men for practical and quick success. methods and expert mechanics can produce. Many See how easy it is for you to get the training that will en- The hours that followed were a confused other standard makes. able you to step to a splendid position and a handsome in- horror and despair to me. Yet there seemed Time payments if desired. come. Mail the coupon right NOW. No frost or obligation. no one but myself and Caan vvho considered Shipments from nearest of our 29 stores. .Order this disaster more vital than those which had now or virile for circular. Resident salesmen ENGINEERING preceded it. At last we knew that the wanted. SSCHOILofof Milwaukee young women of Rax were being stolen- Founded 1905 f rom under our very eyes-from the heart American Writing Machine Co. of the city, in the silence of the Time of Established 1880 Dept. S -1-C424, 415 Marshall Street, Milwaukee, Wis. Sleep. We knew now also, that they were Pactoy. 458-R Centre) Ave., MAIL COUPON NOW being taken into the dread Water of Wild Newark, N. J. Things. Og's presence proved that. Og had gone to live with the fabled humans, SCHOOL OF ENGINEERING OF MILWAUKEE Dept. S.I.C424, 415 Marshall St., Milwaukee, Wis. half -savage, that legend said lived with the monsters of that strange dark region. And Please send me without any cost or obligation, full particu- THE, FINEST 25 lars of the electrical course I have checked and your big now Og had come back-and had been Free Book telling about your institution and how it will fit caught in the very act of an abduction. It CAL.AUTOMATIC me for a big position in the electrical field. Also tell me about your Earn -While -You -Learn plan. was all clear now. And all we had to do (Check courses interested in, and was to guard our women-to watch carefully !MADE be sure to give your education.) the entrance of Wild Things, S chool of Practical Electricity-6 months or 1 year course. to the Water Complete general course, covering entire electrical field. that nothing, human or savage, could come -Institute of Electrotechnics-12 to 30 months' course. Be sure to order Practical electrical training combined with thorough Acad- out of it to trespass on the Marinoid domain. thisnew,improved emic education. 1924 Paramount -College of Electrical Engineering -3 years' course. Reg- model of drop forg ular collegiate work granting B. S. Degree. 14 High School RESCUE PLANNED blue steel, just ont. units or diploma from our Institute of Electrotechnica re- New, positive safety de- for entrance. vice. quired Thus ran the sentiment of the city ; and A world beater for de- NONET -Commercial Electrical Engineering --1 year course. Thou- pendability and accuracy. sands of Trained Men wanted in this new profession. 14 the King, making a speech from the parapet 25 calibre. Shoots 7 shots. BACK High School units or diploma from our Institute of Electro - Regular $22.50 value, spe- IF NOT technics required for entrance. of his palace roof -top, assured us in flowing cially priced at $6.75. SATISFIED School of Automotive Electricity -3 to 6 months. Covers phrases that the danger now was past. No 20 SHOT, all systems of starting, lighting, ignition, and storage bat- of 32 CAL. teries for automobiles, tractors, air -craft, etc. Intensive marauders could come from the Water 20 shot, 32 cal. heavy service automatic, 10 shots $8 45. 'practical course. Wild Things now that we were on the alert with extra magazine, making 20 shots in all, -Armature Winding and Motor Generator Repair Course- special at $8.45. 3 to 6 months' course. Brief, but intensely practical, lead- to stop them. He, our Monarch, assured us Both guns shoot any standard automatic cartridge, ing to well -paying positions. PAY POSTMAN ON DELIVERY plus postage. -Electrical Home -Service Training with laboratory facili- of that. Our women in future, were secure. ties, for those who cannot come to Milwaukee. Had Nona been safe at my side, no doubt Paramount Trading Co., Dept. F I AM, 34W. 28th St, N.Y. I should have applauded these sentiments as WANTED! Name did most of the other onlookers. But Nona The Editor requires for his personal use in his library, the was not at my side. She was gone-into that following copies of the Street ELECTRICAL EXPERIMENTER horrible unknown region from whence none May, June, July, August, September, October, November King said Marinoid women and December, 1913, January and February, 1914. If you 'City State returned. The have these copies, kindly communicate with the Editor, now were safe! What was that to me, with stating the value you place upon them. Address. Mr. H. GERNSBACK my Nona gone? 53 Park Place Age - Education New York City Science and Invention for April, 1924 1287 There was talk of an expedition into the rld's Greatest Water of Wild Things. But none would /eW volunteer, save those comparatively few who already had lost wives or daughters. Caan stood by me. He would go. And I-there would have been no sleep or food for me FREE Written 2 -Year Guarantee Your Proof of Performance again had I tried to stay in Rax and yield SAVE 50 PERCENT up Nona to her fate. and get a "B" Battery and Hydrometer or a Nickeled Auto Spotlight Free There were no artificial weapons available Thousands of Science & Invention readers will slim hunting do just that thru this amazing World Battery in Rax save of one type-that offer. They will buy the famous 2 -year guaran- spear made of fish-bone-the spear with teed World Battery et the lowest price ever quoted and with it they will, get free a hydrometer which the King's attendant had struck me and a "B" Battery or a nickeled Auto Spotüte. down when first I was being brought to Rax. Compare These Prices 5 Per Cent Discount for Cools wills Order These spears were all the Prince and I had Automobile Prices Radio Prices Special 2 Volt Storage Bat- had for our hunting expeditions. s Volt, 11 Plate - $12.26 tery - $5.00 Ford, Chev., Mitchell, Hop., For W. D. 11 d W. D. 12 Other weapons? The Marinoids had had Grant, Elgin, Voile, Saxon. Tubes. Will run200 hours on one charge. Rechargeable. them in times gone by. But once-a life- Volt, 12 Plate - - $14.00 Specialci 4 Volt Storage Bat - Overland Buick Reo, Paige, $ time before-civil war had broken out be- B Aeon. flash, $tude., Dort. For ll. V. 199 Tubes. ame 12 features ea 2 Volt. tween two of the Marinoid cities ; and when Volt, 7 Plate - - $17.00 6 Volt, 60 Ampo. - $6.50 Marank.xwe, ll Dodge, Regal, 6 Volt, 80 Amp». - 10.00 it was over all weapons save the simple spear, F 1#rieçoe d Crow - 8 Volt, 100 Amps. - 12.60 Volt, 120 50 were abolished. There seemed no need of Give year and model of car 6 Amps.Am - 18800 no wild life SEND NO MONEY - weapons. There was practically You need not send a penny. Just clip this ad. and mall with in Marinoid waters. The monster that had Your name and address. The battery you specify will be shipped to you the day your order in received. When the battery amvee, once come to devour them was a fahle out inspect it-read our 2 -year guarantee before you pay one P0607 Convince yourself you are protected from every angle-that the of the distant past. And so they lived on in World Battery saves you 60 per cent. Get the B' Battery and hydrometer, or Auto Spotlit° FREE. Clip the ad. and send your of disarma- order today. a false security-that security WORLD BATTERY CO. ment which is so fatuous-making them- Dept. 1951 1219 So. Wabash Ave., Chicago, Ill. selves defenceless so that they would not be to fight ; and forgetting that their Nickeled tempted EARLE E. LIEDERMAN as he is today / to very defencelessness must prove an irresist- Your Choice Spotlight ible temptation for some enemy to attack them! Do You Need A Bust We organized our meager, pitiful little B" FREE rescue party. Led by Caan and me-with In the Nose Battery and Caan's wife to care for Boy while we were before you start to fight ? Do you need this kind of Hydrometer was no more than fifty of us in treatment to bring you to your senses? If you are gone-there that kind of a fellow, the chances are strong that you total. Then, quite without warning, Prince are going to get it. Atar signified his intention of joining us- commanding us in person. Be Ready Can you guess the joy it brought to my I don't recommend that you be a rowdy who goes AT LAST around looking for a fight. But I do believe you heart? Our Prince, disregarding even the should be alert and, when the time comes, be prepared Intermediate commands of his father, was coming with to beat the ether fellow to the punch. us! The Wise Man Atar-for so I called him now in the in- Radio Frequency Some men never pay any attention to the condition timacy which had come between us-was of their house till it begins to fall on their head. than myself. A slim, clear -featured Others watch for the first sign of a crack and imme- Transformers younger diately have it put in condition. How about the youth, with a boyish smile, but eyes which house you live in your body? Are you going to one to com- let it clog up and waste away until you suddenly had in them the look of born realize you have tuberculosis or some other dreadful. Now you can build a Super Heterodyne mand. And Caan-a man past the zenith of incurable disease? Get wise. Check up on yourself! receiver with the confidence that you will no longer limber Put your both' in shape and keep it so. have "the best there la." You can log his life, whose arms were with An apple is no good unless you eat it. Let it Ile, all stations and select them at will, with youth but with a body strong and and it will rot away. Let your muscles lie idle and clear, loud speaker volume and minimum sturdy nevertheless. With these two to help they will waste away, but use your muscles and you interference. - me I felt that I could conquer whatever have more muscle to use. va..vp'aoo Branston Special Transformers have been testa strange creatures we might encounter-and , designed for this work. Rigorous "The Muscle Builder" move them far superior to anything here- get my Nona back. That's what they rail me. I don't claim to cure _ tofore available. Our party was no more than together, disease. But I do absolutely guarantee to make a Our publication, "Super Heterodyne Con- we were making a strong, husky man out of you. If you wait until come struction." makes It possible for the ama- when Atar announced disease gets you, the doctor is the only one who can and efficient were fifty of us, practically save you-but come to me now and the doctor will teur to construct a complete mistake. There starve to death waiting for you to take sick. I'll put Super Heterodyne Receiver. unarmed. We were too large a party to go one inch of solid muscle on your arm in just 30 days At your dealer's or by our very and two inches on your cheat in the same length of Add Miles Prompt delivery. anywhere in secret; we would, time. But that's only a starter. I'll put an armor write for all Information. numbers be but provoking an attack. plate of muscle over your entire body and build up the walls in and around every vital organ. í'l1 shoot n quiver up your spine that will make you glow all CHAS. A. BRANSTON, INC. over. You will have a spring to your step and a Rash St., Buffalo, N. Y. THE PRINCE'S PLAN to your eye that will radiate life and vitality wherever 816 Main you go. And what I say doesn't just mean maybe. i In Canada. absolutely guarantee these things. Are y'ou with me? and Come, on then. Let's go. Chas. A. Branston, Ltd., Toronto. Ont. Atar's plan, in brief, was that he, Caan and Smiles myself, should slip quietly into the Water of Wild Things and see what conditions were Send for my 64 -page book there. Then, perhaps without ever having "MUSCULAR DEVELOPMENT" been seen or forcing an encounter, we could It is Free in greater return and plan an expedition It contains forty-three full page photographs of force-a force sufficiently great to insure myself and some of the many prize-winning pupils I have trained. Many of these are leaders in their success. business professions today. I have not only given was to :hem a body to be proud of, but made them better To me, whose one and only desire doctors, lawyers merchants, etc. Some of these came follow Nona and get her back, the Prince's to me as pitiful weaklings, imploring me to help them. Look them over now and you will marvel at their demands the words seemed rational indeed. What did I present physiques. All I ask is 10 cents to cover other Marinoid root of wrapping and mailing. For the sake of your care for the safety of those future happiness, send for your copy today-right now BRACH girls who had been stolen? -before you forget it. The Prince, nevertheless, was right from vac - 9 dio every angle, and so it was decided that we EARLE E. LIEDERMAN three should go alone. Dept. 204. 305 Broadway, New York City ARRESTER I shall never forget the scene as the parted from his mother on the roof- EARLE E. LIEDERMAN, Prince Broadway, New York City of the Palace. We were going to what Dept. 204, 305 to protect, top Dear Sir: I enclose herewith 10 cents, for which you made everyone considered almost certain death. are to send me without any obligation on my part whatever, a copy of your latest book, "Muscular not to meet a price We would go, and they would never see or Development." APPROVED by the NATIONAL hear from us again. BOARD of FIRE UNDERWRITERS But with these Marinoids there were no Name SOLD BY ALL DEALERS heroics. No shouting and applause as the Street L.S.BRACH MFG. CO. heroes went forth to battle. That is left for N EWARK, N. J. war City State you really civilized humans who wage (Please write or print plainly) after a more vainglorious fashion. 1288 Science and Invention for April, 1924 These Marinoids, crowding every corner of the cube of open water before the King's palace, hovered in silence as we prepared to leave. And the silence deepened as the Queen stood before her son, and he knelt at her feet. "Goodbye, Atar," she said; and her glance included Caan and me. "We will wait and hope-for you to come back." Her arm brushed his sleek head as he rose and turned away. We departed; and her brave, inscrutable smile followed us, as between those silent, solemn ranks of specta- GETS 'EM FROM tors we slowly swam along the streets and COASTS out of the city. TO COASTS Clearly and distinctly, too! For our users Cincinnati hears tell us that And presently, with tumultuously beating Frisen, Denver hears Schenectady, New York hears Havana! Scores of long distance records were hearts, we three with only our slender spears, made on these instruments last year so with the many new refinements Incorporated the result obtained now were approaching that dread black opening will be far better than ever. which marked the entrance to the Water of HIGHEST QUALITY AT LOWEST PRICE Wild Things. This has always been the MIRACO hey -note and the thousands of sets now in use are a fitting tribute to Thousands Can Draw V M1RACO'S excellent performance. Many new improvements, such as new sockets resting on chock -absorbing pads-a refinement found only in the most expensive We entered the opening, swimming in a sets-rheostats with multiple resistance windings, making group with Atar leading. It was already it possible to use either dry cell or storage battery tubes, and a new aluminum shield that prevents annoying body CARTOONS new territory for us. Our hunting expedi- capacity effects, are embodied. Cabinet is of soliti mahogany-workmanship tions had never taken us even as ; the fittest far as this -operation extremely simple yet Who we were always content remain in always dependable. Have NeverEvenTried to Marin- 2 tube outfit shown above $29.50 Cartoonists earn from $60 to far over oid waters. As we advanced, the rocky ceil- I tube outfit 18.50 $300 a week. Why tie yourself 4 tube outfit shown below 54.50 to work ing overhead was closing down on us, until Write for our that is drudgery when through a re- new bulletin today. markable new method you can easily soon there was no more than twice the DEALERS-JOBBERS learn at home in spare time to draw length of our bodies between it and the floor. Write for our proposition quickly. cartoons that SELL? AGENTS On both sides the dark water stretched out There's still some territory open-Write or wire. MANY are earning pitifully small salaries who could make wonderful salaries in car- as far as we could see into blackness also. tooning. Briggs, Fox, Fisher, Goldberg We were descending now at an angle of per- and other leading cartoonists earn snore than the haps forty-five degrees. President. Yet a few years ago many of our most successful cartoonists never dreamed they We had gone what you would call a mile could draw a good cartoon. possibly, when we came suddenly to a tangle The World's Easiest, Pleasantest of coral-a barrier that reached from floor and Best Paying Profession to ceiling. I call it coral. It might have Just watch a cartoonist work. A few little lines-a been a petrified vegetation. All all but im- Coople of simple curves --a splash of black here and there -and then you see a splendid cartoon before you. With penetrable thicket-white like the frosted THE MIDWEST RADIO COMPANY a few strokes of his pen, he has taken some little inci- underbrush of your Northern winter forests 809 Main Street. Cincinnati. Ohio. dent of his day's experience-some humorous or sad scene he has witnessed-and produced a wonderful cartoon. -it seemed to bar our further progress. New Easy Way to Learn Cartooning We stopped; consulted, and swam to the This fascinating ability to draw cartoons can now left and right. But the tangle extended in easily be yours-this ability which can mean so .much real pleasure and profit to you, Through a wonderful both directions to the edges of the mile -wide new method you receive right at home through die mall passageway. a complete training in Cartoon Making, and personal corrections on all of your work from one of America's "It is this," said Atar, "which keeps our most prominent cartoonists! own region of With his. help, you ran in an amazingly short time free monsters. They cannot leant to draw the cootie strips, humorous, political and easily pass a barrier like this." He was animated cartoons width are In such big demand. smiling at Caan and me. "To this, perhaps, Learn More About Cartooning we owe our safety." A Quick Way Send for FREE BOOK Caan was poking at the thicket, and we Never have cartoons been so popular. Millions of to Big Pay Work dollars were spent last year on cartoons of all kinds- found after a moment that we could with For just a few weeks-loan and every week newspapers increase the amount of car- difficulty force our way through it. me an hour a day of your toons used. Get full details on the amazing opportunities spare time. to in this fast growing field of Cartooning and full infor- The realization that Atar's words brought I will want mation on this remarkable home study method. Mail put you in the $100 a week coupon for FREE BOOKLET today. us was at once reassuring and alarming. If class, as an auto expert. WASHINGTON SCHOOL no creatures of the wild could pass this bar- Don't quit your job-stay OF CARTOONING home. Thousands of men are oom 264, 1I13 -15th St., N. W. Washington, D. C. rier, what then might lie on its other side? making big salaries. Others Caan, older and more poised than either i earning huge profits in their WASHINGTON SCHOOL OF CARTOONING. Atar or me, was wasting no time on such own business. You can do the Room 264, 1113 -15th St., N.W., Washington, D. C. J. R. eayston, Pres. same. I will show you how. Please send me without obligation your illustrated thoughts. FREE BOOKLET on Cartooning and details of Free "Come," he said. "Here we can get Offer. through." Learn at FREE Name (Write name The white underbrush must have extended Kit of Tools plainly-State Mr.. Mrs. or Miss) You get a set for several hundred feet back and downward. HOME! of One tools- Address Auto Repairing! Battery! worth $15.00 We forced our bodies through it, seeking FREE. We City State small orifices, bending aside the twigs, or Auto Electricity! Welding! show you Vulcanizing! how to make If under 16 years, please state age breaking them off for they were very brittle. My copyrighted "Job -Way" sys- quick money tem teaches you in an hour what with them. We were an hour or more getting through. ordinarily takes a month to learn. Hurry and A few small bottle -shaped fish with protrud- Interesting work. Intensely get details of practical. Makes you a ape. our offer I CAN ing, ball -like eyes on the sides of the head, cialist In every branch of auto- Anyone cal-RN! lurked here and there. They watched us motive work. No talent nr e erienco necessary. ' i. Feud tiny work Pays erTE a curiously - unafraid, almost resentful it A Business of Your Own Co plate instruction book TELLS ' y H, ABOUT: Ai habeta Colors, HOW Op W seemed, with their sidelong glances and their Big opportunities in the city and on the farm. TO MIX PAINTS, $how Cards. 15,000 000 autos to repair, 15,000,000 batteries to serv- Window Board and Wall Signa, SJ'40, hasteless movements to avoid us. But we ice 15,000,000 ignition Ready made lettere. Gilding, systems to keep going. r-. said S 65,óO0,000 tires to Bell and repair, 8,000,000 trucks to TRICKS OF THE TRADE lao paid them little heed, for such as they often overhaul. given 100 Alphabets d Designs. $ook - Employers need auto experts and pay $100 bound in flexible Ifus bstther, edges, dS wandered into Marinoid waters and were a week or more to get them. Aleo, endless oppor- 4>artn tunities to make big money in a business of your own. Pens Book and PeuSsent poutpatd easily killed with our spears. for >3.00. (C. O. D toc extra. 1 OgilviePub.Co.,S7ROseSt.,DeptiO9NewYOrk The tangle of white underbrush gave way for Free Book IIf`/7 at last into open Again II EARN MONEY/MMED)ATELy- water. we saw the Write and Free Lesson WE FURNISH EQUIPMENT TO START ceiling and floor close together-the same Learn how you can make 83,000 to $8,000 a year as an narrow slit sloping sharply downward. Automotive Expert. Read our "Money back guarantee." Send for free book. Read the Free Lesson. With the white underbrush gone, the water Find out about my practical "Job -Way, Method. No. Special low price and easy terms, too. Write today. CROSLEY RADIO seemed darker-so dark that we could hard- Book is free. No obligation. Just Bend a postal to complete ly see each other a few lengths away. It Chicago Automotive Institute JC equipment was warmer too-unpleasantly warm; and This standard $85.00 outfit includes GIVEN 536 S. Clark St., Dept. 1254 Chicago, DI. batteries, tubes, phones, EVERY- to our nostrils came the taint of that stench THING-ready to set up and TUNE IN. We want you to introduce our new perfume to ONLY 20 of now unmistakable. Insure your copy reaching you each your friends. Quality_and satisfaction C.JARAN- TEED. Write for FREE. details. ON SEARCH month. Subscribe to Science and Inven- THE BABBITT CO. 1022-C Arch St.. PHILA., PA. tion-$2.50 a year. Experimenter Pub- We had been swimming downward for lishing Co., 53 Park Place, N. Y. C Science and Invention for April, 1924 1289

what seemed an interminable time when abruptly the floor beneath us dropped away FAHNESTOCK'S into a perpendicular cliff. Simultaneously the ceiling had heightened-disappeared into LATEST RADIO HELP the watery shadows. We found ourselves poised with a vast void of ink before us. It might have been illimitable for all we could see of its boundaries. And empty! There was nothing but blackness-but it was that pregnant blackness that seems, not empty but merely to conceal. "We must go down," said Atar. I could hear that he was trying to keep his voice steady. "They would live-down on the sea -bottom." We descended along the side of the perpendicular cliff. A thousand feet? Three thousand? I cannot say. The water grew steadily warmer until its heat began seriously No. 31 to oppress us. The thought came to me sud- THE denly that we were well into the bowels of my meteor ; its internal fires, now very close Antenna Connector perhaps, were heating the water. My meteor! How remote the outside world-the outer Price 10c surface-the Heavens-Saturn-the stars and the vast, unfathomable distances of the Snap larger connector over Stellar Universe-seemed to me now ! I Antenna Wire; insert Lead-in had been born out there somewhere. It was You Wire into smaller clip and a per- the first time in ages that such a memory Want to Earn fect connection is the result. had crossed my mind. Big Money! At Your Dealers "Look I" cried Caan softly. And you will not be satisfied unless We huddled together against that black you earn steady promotion. But are cliff -face. Below us in the void, a glowing you prepared for the job ahead of Fahnestock Elec. Co. point of light was moving. It seemed miles you? Do you measure up to the LONG ISLAND CITY away; but it was no more than twenty or standard that insures success? For thirty feet, for as it approached we saw it a more responsible position a fairly NEW YORK was a long, sinuous thing with an illuminated good education is necessary. To write head-a head that glowed phosphorescent, a sensible business letter, to prepare luridly green. estimates, to figure cost and to com- We held our breaths. The thing went past pute interest, you must have a certain us-quietly, without seeming to notice us. amount of preparation. All this you It was a ribbon-like thing thirty feet long, must be able to do before you will two feet high, and no more than a few inches earn promotion. TONE TESTED thick. A pallid white ribbon of puffy slime, Many business f rayed and tattered at its edges, it undulated houses hire no men Radio Headsets whose general knowledge is not equal to a gruesomely. from end to end. In a moment high school course. Why? Because big it was gone, into that void of ink from business refuses to burden itself with men who are barred from promotion by the lack whence it had come. of elementary education. Again we descended. Other creatures passed us-headless things of black with il- Can You Qualify for luminated parasites clinging to them; great fishes, star -shaped, with a brilliant green a Better Position? head in the center and each point of the star We have a plan whereby you can. We as long as our bodies ; fishes, or were they can give you a complete but simpli- yOU can afford to have several at this animals ? that were all head, it seemed. fied high school course in two years, price. Our guarantee protects you. We took heart, for none seemed to notice giving you all the essentials that form Equal to any headset on the market in perfect reception of broadcasting. Send us. But there was a balloon of white jelly. the foundation of practical business. $3.00 by registered mail or money -order. It floated past us quite close. It was larger It will prepare you to hold your own We will ship C. O. D., if you prefer. than any one of us. It seemed harmless where competition is keen and exact- Prompt shipment-we pay postage. Ask it. suddenly for our and Atar swam beside Then ing. Do not doubt your ability, but Free Catalog of Radio Parts the thing expanded, lost all its form and like make up your mind to it and you will soon mist, have the requirements that will bring you EDSON RADIO SALES CO. a cloud of white enveloped him. He success and big money. YOU CAN DO IT. 4 Elmwood, Providence, R. I. screamed and we rushed to his rescue. In an instant we were all three plunged Let us show you how to get on the road to success. It will not cost you a single 1 into a confused, frantic horror for which I working hour. It costs you nothing but can find no words. Like thick white glue a stamp. life's Secrets! that was sticky, yet slimy, this almost im- American School Amazing newbook,"Saf.0 1 ponderable stuff fought with us! Fought, I just out, tells ou the things You want to know straight from the shoulder. Gves ad it was using an intelligence against Dept. H.426 DrexelAve.&58thSt.,Chicago vice to newly married. Explains anetomy of say-for re roducti ke organs, impotence, lawn of Sex: us! We floundered, flailing the water with Lll'e, mistakes to avoid, diseases, preen cy etc. Contains 9 startling Maurine: 1-9etenee frantic arms and legs. A noisome stench Eugenics, 2-Love. 8-Marriage, American s-FarmsZLife 6-SexosfSelenee,Science, 7- from the gluey stuff sickened us; the feel of School Hygieee anddYDisorbere, 8 -Heel th and Dept. H-426 Drexel Ave, and 58th St., Chicago Hygiene. of Life. in e11, 104 chn- flesh ters, 77 illu.trations, 612 page, Examine it made our crawl and the gorge rise Sena me tull information on the subject checked at our risk. Mailed in a plain wrapper. in our throats. It was uncannily flimsy stuff. and how you will help me win success. We could tear it into shreds, fling it away; ,...,Architect ,,,..Lawyer Send No Money .....Building Contractor .....Machine Shop Practice Write for yourcopy today.{ Don't send s but always it came back, to weld itself to- cent. Pay 91.98. pine .....Automobile Engineer .....Photoplay Writer on arrival. Money refunded If eatlsfacfúry, gether. There was an intelligence in it! ....Automobile Repairman ....Mechanical Engineer FRANKLIN ASSOCIATION .....Civil Engineer Dept. 53-34 81 E. Madison St., Chicago. Ill. Not a centralized power of thought, like a .....Shop Superintendent .....Structura l Engineer ....Employment Manager brain, but an instinct for battle that must .....Business Manager ...-Steam Engineer Straightens Shoulders have been inherent in every smallest fibre of .....Cert. Public Accountant ....Foremanship -Increases Pep it. Accountant and Auditor .....Sanitary Engineer THE NATURAL BODY BRACE-Corrects .....Bookkeeper ....Surveyor (& Mapping) stooping shoulders, straightens the beck, gives We escaped at last. How, I do not ...-DraftsmanandDes er ...-Telephone Engineer the lungs chance for normal expansion, induces know. Perhaps the thing wearied of us...... Electrical Engineer .....Telegraph Engineer proper breathing. Bringe restful relief, comfort...... Electric Light & Power .....High School Graduate energy, and pep. For men and women. And as we struggled away exhausted, with .....General Education ..._Fire Insurance Expert its horrible gluey particles which we had .....Vocational Guidance .....Wireless Radio Costs nothing to try it .....Business Law -,-Undecided Write for 30 day° free trial offer and free book. breathed in choking our lungs-we saw it NATURAL BODY BRACE CO. floating off, ragged but still balloon -like, its Name Howard C. Rasb.Rt286 Hash Bldg., Salina, Kama original shape almost unimpaired. Address.. GOTT. H NEEDED SEARCH CONTINUES linen, women,Y. gir7, willing to accept 1 Government Positions, 5117-1250, stationary, ator near home, or traveling, Write, Mr. Ozment,883, We reached at last the bottom of the void. 8$. Louis. Mo. immediately. It was not level, but tumbled as though some 1290 Science and Invention for April, 1924

cataclysm of nature had tossed it about. Banks of black ooze, a hundred feet high, Magnified were honeycombed with holes ; valleys were beside them-valleys bristling with stalactites 225 Diameters of black and white coral which stood up like This is what the tip pointed spears to impale the unwary tres- of a fly's leg is like when seen thru the passer. And there were miniature volcanic - looking peaks-cone-shaped. From one of Wonderful New them a stream of water almost hot, was issuing. Ultralens Frequently now, we saw lights ; and all of them were the naturally lighted heads and bodies of swimming creatures. They moved about lazily, confidently, ignoring us ; and we MICROSCOPE knew that when they were hungry they At last the high powered microscope is within the reach of all de would feed, either upon others smaller of who wish to study, observe and their kind-or upon us. experiment with the vast world of minute objects that are invis- Over this tumbled, broken sea-bottom- ible to the naked eye. A remark- for where occasionally a giant crab or something able discovery enables us to man- Complete ufacture the Ultralens Microscope Outfit. of the kind would scuttle from a shadow (magnifies 225 diameters) for one- prepaid "I'm making real into one of the deeper shadowed holes-we eighth the usual. cost. swam at an altitude of about fifty feet. We moneyy now" carried no. light ; and our bodies were EASY TO USE! shrouded in green -black cloaks. We still held Any amateur can immediately start using "sEB that coupon? his Ultralens to examine the edge of a razor, Remember the day our ! you urged me to send it to Scran- spears-poor, useless, futile things Yet, the mesh of a cotton shirt, the bacteria in ton? It was the best thing I ever did. as Atar said, they might not be useless dirty water. No technical training required "Mr. Carter called me in to -day. Said against humans. And it was the humans, yet hundreds of scientists he'd been watching my work for some with their greater intelligence, that we now and teachers are using this time-ever since he learned I was study- instrument today. It is at ing with the International Correspon- feared most. Conditions of life here in the once interesting, instruc- dence Schools. Water of Wild Things, now became plain tive, and scientific. Gives "Then he asked me if I thought I could to us. These wild creatures were for the enormous magnification and take over Bill Stevens' job. I told him perfect definition. I was sure that I could-that I had had most part inoffensive up to the point of satis- Compact that goal in view ever since I started my fying their own need of food. They fed The Ultralens Microscope I. C. S. course. upon each other and thus reduced their num- comes packed in a beautiful "I start to -morrow, Mary, at an in- ber. The humans, in open battle with them, Bakelite case with full increase of $60 a month. It's wonderful tructions that anyone who how spare -time study helps a man to were doubtless helpless. But the humans can read can understand. get ahead." had the intelligence to hide-to escape. And Lenses of 125 x and 325 x VCR thirty-two years, been the creatures not bother objectives can be furnished the L C. S. has helping of the wild did un- at $1.50 each. A' men to win promotion to earn more money, to get duly to pursue them. ahead in business and in life. ORDER TODAY You, too, can have the position you want in the Does this seem illogical to you? I assure Order direct from this advertisement and work you like best. Yes, you can. you, it is not. The conditions we found, get your Ultralens Microscope now. Fully All we ask is the chance to prove it. Without cost, here in the Water of, Wild Things, in the guaranteed. If, however, you desire more without obligation, just mark and mail this coupon. information before purchasing we will glad- bowels of that meteor flying amid the Rings ly send free descriptive catalog. INTERNATIONAL CORRESPONDENCE SCHOOLS of Saturn, were almost identical with those Box 6230-C, Scranton, Penna. SCIENTIFIC APPARATUS Without cost or obligation on my Dart, please tell me which prevailed in the early periods of your CORP. bow I can qualify for the position or in the subject before Dept. 203 MILTON, PA. X: own Earth's history. There is not, and which I have marked an never has been, a creature as predatory, BUSINESS TRAINMIG COURSES wild Business Management D Salesmanship as ferocious as Man himself. Your lion and Industrial Management Advertising cowards Personnel Organization Better Letters tiger are unless spurred by fright MASTER7 Tramc Management ['Show Card Lettering or hunger. The wild animals of your Earth LiBusiness Law D Stenography and Typing iTijzz, \saZT Banking and Banking Law Business English would have been glad to live at peace with JLE ri.Zrme 101 Accountancy (Including C.P.A.) Civil Service Mankind. It has been Man himself who Here is D Nicholson Cost Accounting Railway Mail Clerk one difference between the Burgess School Bookkeeping Common School Subleete consistently has been the aggressor. and other correspondence schools-I am so confident Subjects that you can master electricity at home by means of °Private Secretaryp High School "See there!" cried Caan softly. "Is that the famous Burgess Electrical Course, that I accept Spanish D French Illustrating your enrollment with distinct understanding that you TECHNICAL AND INDUSTRIAL COURSES perhaps a place where humans live?" pal me only for what you get and you can stop at Electrical Engineering Architect any time you feel you are not getting all you pay Ll Electric Lighting Blue Print Reading Below us, in the distance ahead, were a for. NO OTHER SCHOOL DOES THIS. YOU Mechanical Engineer Contractor and Builder number of tiny pin -points of light. And CAN'T LOSE. Mechanical Draftsman Architectural Draftsman ENDORSED BY EXPERTS Practiceflee Concrete Builder even as Caan spoke, a human figure passed Electrical Engineers not only endorse but siso take MachtneRailroadPositionsShop Position s Structural Engineer my course. This is the best recommendation possible. OGas Engine Operating NChemistry Pharmacy near us-a figure swimming swiftly down- Write for My Catalog. Clvll Engineer Automobile Work ward with a fugitive, frightened speed. It A STRAIGHT -FROM -THE -SHOULDER TALK on Surveying and Mapping Airplane Engines your future in the Electrical Industry-. No mystery. Metallurgy O Mining Agriculture and Poultry seemed to hold a sort of lantern in one of No bunk. Just an honest statement of how I have Steam Engineering Radio Mathematics its hands outstretched-a small, shrouded helped thousands to better jobs. Let me help you too. All you need is determination and the ability Name light to guide it through the darkness. It to read and write. Street n-a+.aa did not see us, and in a moment it had passed ASK ABOUT SPECIAL OFFER ON NEW Address RADIO COURSE downward into the shadows. But the moving BURGESS ELECTRICAL SCHOOL City State point of its light remained visible. Yorke Burgess, Superintendent, Dept. 9, 745 E. 92nd Street, Chicago, Ill, 201 Occupation "Come!" urged Caan softly. "That will Canadian Branch, C. Crawford Ave., Toronto. Persons residing in Canada should send this coupon to the show us the way. Hurry !" International Correspondence Schools Canadian, Limited. Montreal, Canada We swam downward, following the point ELECTRICAL HANDBOOK of light. We have prepared a pocket note book for practical men. Con- tains drawings and diaa,u,n, of electrical machines and connections: over ZOO formulas. with problems worked out Build It Better-Quicker-Easier VI "THE BURGESS BLUE BOOK" roman. drawn.. for Motor Sea n... C.n- Tran,tormer.. Reee.nna Sa,her.a Liehu ne C,rruna Cautatt.aak tn. With a e.Iler,elude El., cal Matha .. Una.. Re. e. War. Gaup, Rule.. Ohm. L.w, Unknown Remo .n.... Dynamo Trouble. A,i, Al,.rn.eng Curr.,,' C.leuk. The light ahead of us winked like a will- none. Bodine Impedance, JUNIOR Frequency. Seeds. Power F . Formulae fqr Lm. Trsneform.' Rie m SI 00 ea.lo.,d on my y o'-the-wisp as back e e BENCH SAW intervening branches of coral, AGENTS WANTED: the edge of a mud -bank, or perhaps the body THE BURGESS COMPANY, Consulting yElertrieal Engineers Does your rippin 745 East 92nd St. Radio Apparatus and Supplies Chicago, Ill; mitering, grooving, of some living creature, momentarily blotted rabbeting tenoning it out. sanding, grinding, and We were close to the bottom now. many other operations Along here it was a rolling, but fairly even with surprising ease and accuracy. Top 10"x13". Saws 1Ye" stock. Dadoes %"x%", Machine bank of ooze, with grotesque squat plants DON'T WEAR built entirely of metal.. Driven by t/a or 1 /3 hp. motor. growing in it. Portable. Attaches to any light socket. Extremely accurate. Descriptive circular tells many things of The light could not have been more than A TRUSS interest to workers in wood and soft metals a few hundred feet in advance of us ; in its BE COMFORTABLE W. & J. Boice, Norwood .4 Toledo, Ohio glow we could sometimes see the outlines of 1730 Ave., Wear the Brooke Appliance, the modern the human figure carrying it. We dici not scientific Invention which gives rupture dare speak aloud now ; we swam with that sufferers immediate relief. It has no obnoxious springs or pads. Automatic speed and silence which only one who lives Air Cushions bind and draw together in the water can attain. the broken parte. No salves or plasters. print or PROFIT Mr. C. E. Brooks Durable. Cheap. Sent on trial to prove . Printers' ages so high you can make big Presently its north. Beware of imitations. Look for trade -mark bear- money in spare timo. Presses$12 to$295. Pay the light dipped downward and ing portrait and signature of C. E. Brooks which appears on for themselves in short time. Write for de- vanished. We saw that this figure we were every Appliance. None other genuine. Full information and taiis and catalog presses, type, paper, cards booklet sent free Conn. in plain, sealed envelope. etc THE PRESS 00. X-47 Meriden.. following had entered a black cave-mouth- BROOKS APPLIANCE CO., 172 State St., Marshall, Mich. Science and Invention for April, 1924 1291

an opening which ran diagonally down into a slimy bank of mud. And we saw, too, DEAFNESS OVERCOME that the points of steady light which had first attracted our attention were the reflected glow of illumination from somewhere be- IN EIGHT DAYS neath the sea floor. Silently we slipped into the cave -mouth. The moving light was down there ; then The terrible affliction of deafness and the nerve abruptly it disappeared. racking misery of head -noises need be suffered no "Wait!" whispered Caan. "Go slower !" longer since the announcement of a remarkable new We advanced, cautiously-and came again treatment. Now it is possible for some of the most to a hedge of coral which impeded our pas- obstinate cases of deafness to be relieved quickly sage. But this barrier we saw at once was by the application of a prescription formerly known artificial. It was the crude dorway- as Rattle -Snake Oil. This treatment, now dis- created by human intelligence and industry- tributed under the name of K-17, is meeting with which barred the creatures of the wild from wide success all over the country. entering. We threaded our way through it. J. B. Sisson, an Alabama resident, says, "Started Any one of those sea -monsters could llave your treatment October 1st. On the 9th I could battered it down had he known his strength. hear speaking across the room distinctly. Head - But such a knowledge is given only to Man. noises and pains in neck have stopped. I can Beyond the barrier the dim glow of a hear wind blowing for first time in seven years." diffused green light became visible. We K-17 is easily used at house and seems to work edged cautiously forward, turned a corner, almost like magic in its rapidity, on people of all came suddenly to a ledge, and stopped- ages. Cases of over 22 years' standing have been breathless, with wildly beating hearts. cured in a week's time. We were looking down from near the ceil- So confident are- we that K-17 will cure you, ing of a cave. The water filling it was that we offer to send a large $2 treatment for only lighted with a pale green radiance, that lent $1 on 10 days' free trial. If the results are not a ghastly, wavering unreality to the scene. satisfactory, it costs you nothing. The cave might have been several hundred Send no money-just your name and address feet in width-nearly circular-and shallow, a hundred to the Greene Laboratories, 71 Greene Bldg., feet perhaps from floor to ceiling. Kansas City, Kansas, The opposite wall to us was plainly visible. and the treatment will be It mailed at once. Use it according to the simple was gouged out with niches in ranks and Famous Course in directions. If at the end of 10 days your hearing tiers-shallow ledges like the houses of your is not relieved, your head noises gone entirely, ancient, most primitive "Cliff -dwellers." We just send it back and your money will be refunded could see little family groups squatting on without question. This offer is fully guaranteed, many of them-humans, not unlike the BOXING so write today and give this wonderful compound Marinoids in form-men, and women, and Jiu-Jitsu & Wrestling a children. trial.-Adv. This great boxing course-six big books mutate log 281 But it was none of this that caused our pages and 250 photographic illustrations-teaches you in Your own home the secrets of ring science, and the Was hearts to leap so wildly. The floor of this and guards of the world's greatest boxers-Jack Dempsey, \\111//f//////i community house was at the moment crowded Benny Leonard, Mike Donovan. Bob Fitzsimmons, Kid McCoy. All for $1.67! And you can have it on 10 -day with human figures. The figure we had trial. Send no money. followed in was By this wonderful short-cut method Marshall Stillman ION swimming downward to join teaches you how to hit, guard, duck, clinch, feint, judging IBM them. On a raised platform-a shelf of distance and time scientifically. He cuts the time of a learning in half. In addition, he gives you three snappy ooze at the side and bottom of the cave- rounds of Shadow Boxing, combining the cleverest blows used in the ring-great exercise for developing wind, Which Aerial- several old men were sitting. They were not speed and confidence. Marinoids-but they seemed to differ prin- nu -Mau and Wrestling is also included-how to dis- Wire or Ribbon? 'kw- arm an opponent, hew to throw him if he grabs you from cipally in the eyes, which were much larger behind, how to break a strangle hold, the Gotch Toe Hold, /111111W\\\\\\1 and more vacant, and in the pallid, ghastly the Stecher Scissors Hold, the Head -lock, etc. History of Boxers: With the course you get a history whiteness of the puffy flesh of their bodies. of famous boxers right up to the minute, with such fam- OUR Aerial is a part of your ous fights as the Dempsey-Firpo, Firpo-Willard, Demp- Receiver! lion 't blame your set for On the same platform, stood Og! He was sey -Gibbons fights, illustrated with ringside views. unsatisfactory results.. Nine gazing down at the throng of people before Send no money: Simply fill in and mall the coupon. times out of 10 the fault is In the Aerial. Try When you have the course in your hands, deposit $1.67 the sensational new TRANSCONTINENTAL "Rib- him-haranguing them. His voice reached (plus the actual postage) with the postman. Then use bon" Aerial-adopted by Radio Engineers, broad- the course 10 days-try it out thoroughly. If for any casting laboratories, and thousands of enthusiastic us-not Marinoid words, but enough like reason, you are not entirely satisfied, return the course, radio fans. It's guaranteed to give clearer tone, them-a corruption-to make them intel- and get your money back at once. Mail the coupon now bigger volume, greater distance, sensitiveness and to Marshall Stillman Association, Dept. 1424-D, 50 East selectivity or money refunded. ligible to us. 42nd Street, New York. 500% better results with the All this we saw at a brief glance. And the crowning thing: On the platform also, sensational J between Og and the white old men, my Nona 10 -DAY TRIAL was sitting with her arms bound at her Marshall Stillman Association. TRANSCONTINEII'A!11 Dept. 1424-D. 50 East 42nd St., New York, sides! My Nona, beautiful as always, pink You may send rite on approval the Marshall Stillman Course. When the course Is handed to me, I will de- skin, blue eyes and golden hair-so vivid posit $1.67 (plus the actual postage) with the postman, lj,. amid that pallid, ghastly throng! And she with the understanding that if, after ten days, I wish to FOR SD COPPEj return the course I may do so and my deposit will be FOOT R was unharmed-with spirit unbroken-I instantly refunded. If I keep the course, there IS C o 1f - AERIAL could see that by the flash of her eyes, her to be nothing further to pay. PLETE weather proofed! gaze it Name 75 ft., $2.25 to resist c . Based o scientific scornful, unwavering as she leveled 100 ft., $3.00 principle that broad surface incres re - Address ft.,$4,50 cepuvuy sod amplifies the tone. Equally at the puffy white faces staring up at her. 150 tiafactory with tune crystal sets. Canadian and foreign orders must be accompanied by Comlete, r'Twist it I " is FORREST, the famoua My Nona! cash ($1.67 U. S. funds) subject to money back guar- readyfor use radio expert.. S twists per 60 feet catches antee if not entirely satisfactory. snapsolderedoksto directions." VII Order from odi if your dealer will not faapn tO plplY fastenul on to witho Yon pro pay DEALERS and Are you, my reader, wearied of me? Per- er,awit .no.o AGENTS! Write insulBtoI& with order, or CD. f r attractive haps you are, and I am a proud old man who plus postage. Now sold propoeillonstodayl is good radioato es, all over the U. S. Big sal ca, good will force his words upon no one. You Charge Your Battery pecounrwecpint ACORN RADIO MFG. CO., the country so pt perhaps can anticipate what further adven- For A Dept 207 laos S. Racine Ave., Chicago Nickel tures befell me ill this dark and curious The Gold Seal Homcharger is culmi- charges Radio and Auto Bat- world. And what, after all, their teries at home overnight for a nation to you! To me they are glorious nickel. Your dealer has it. memories the deeds of my youth-and Write for FREE booklet and A PE FELT NOSE of list of broadcasting stations. shaped at home while you age lives upon its memories, as you know. The Automatic Electrical sleep. Rapid, painless trey' ces Co. and safe. The ANITA is To you, these memories of mine, mean- 116 W. 3d St.. Cincinnati. O. the ORIGINAL and only what? A chance to laugh-to ridicule? comfortable NOSE AD- JUSTER absolutely guar- I am too sensitive perhaps. Mayhap I do anteed and highly rec- some of you, indeed, ommended by physicians. you an injustice. That WinnerooldMetial Fels. 1923. Write ask me earnestly to tell you of my past, is Factory to Rider for FREE booklet. The ANITA CO.. I you for it. I will tell Saves $10 to $25 on the Ranger Bi- 9E FORE AFTER Dept. 473, Anita Bldg., Newark,N.J. gratifying, and thank cycle you select from 44 Styles, colors you more if you really wish it-tell you as and sizes. Delivered free on approval express prepaid for 30 Days' Free Trial. elllenlllllllllllllllll Illlanlllllllllllellal111lllllllllllllllllllllllllllllllll1111lllllllllllllll,llallllllelllllnlll.. best I may, the plain and simple truth of my deemed. Possession and $S Monthtfnee at once 1. our nders I copy you each queer and clouded life. Or, if you prefer, Monte ly Deymmppian- Bieyclea and up. Insure your reaching ie, equipment half ea - month. Subscribe to Science and Inven- I will have done-lock it in my heart and relampuel prices.Write for marvelous new alone. prieea,wopdertul a0davtrial offer and terms. tion-$2.50 a year. Experimenter Pub- live it over for myself CYCLE CO'IPAKY is you to say. Write fur lishing Co., 53 Park Place, N. Y. C. It for 11EPTA I97CHlCAO tree catalog alllellanlllaaaW W Wulallaeeelllnlneelllnlelmnnnneennnnnllneenlenlnelllllneleeellllllllar END PART IV. 1292 Science and Invention for April, 1924

Ielk .,,' .,,,,. .. Opportunity Ad -lets yOU will find many remarkable opportunities and real bargains in these columns. It will pay you to read and investigate the offer- ings made every month by reliable firms, dealers and amateurs from all over the country. No matter what you may be seeking, whether supplies, automobile accessories, the opportunity to make money, or anything else, you will find listed here the best and most attractive specials of the month. Advertisements in this section twelve cents a word for each insertion. Name and address must be included at the above rate. Cash should accompany all classified advertisements unless placed by an accredited advertising agency. No advertisement for less than 10 words accepted. Ten per cent. discount for 6 issues, 20 per cent, discount for 12 issues. Objectionable or misleading advertisements not accepted. Advertisements for the June issue must reach us not later than April 15th. The Circulation of Science and Invention is over 177,000 and climbing every month EXPERIMENTER PUBLISHING CO., INC., 53 Park Place, New York City. N. Y.

Agents Wanted Agents Wanted (continued) Business Opportunities Agents-Best If you're in selling make money and you want to You can have a business -profession of your own and seller; Jem Rubber Repair for tires and to earn big income in service fees. A new system of tubes; supersedes vulcanization at a saving of over 800 make the greatest amount of it, and you want to do it in a home per cent; put it on cold. clean, legitimate, dignified business that is foot correction; readily learned by anyone at in a It vulcanizes itself In two permanent, few weeks. Easy terms for training, openings every- minutes and . where every sale means a satisfied customer and a repeat is guaranteed to last She life of the tire or where with all the trade you can attend to. No capital tube; sells to every auto owner and accessory dealer. For order as well as an immediate profit, get in touch with us particulars how at once. We've got the proposition for you and we're pre- required or goods to buy, no agency or soliciting. Ad- to make big money and free sample, address Laboratory, 18 Back Bas, Boston, Mass. dress Amazon Rubber Co., Dept. 601, Philadelphia, Pa. pared to prove it to you with Facts. This is addressed Stephenson particularly to you men who are tired of selling catch -penny Stop Plodding! Be Successful. Operate a Tire Re- Big money and fast sales. Every owner buys gold novelty and luxury Slake big profits in any locality. We teach initials for his auto. Ycu charge $1.50; make $1.35. jimcracks, articles, as well as you new pair Shop. Ten men who are just starting anti want to get started right. you and furnish complete equipments $100 up. Book of orderá daily easy. Write for particulars and free It will cost you nothing to investigate. Anti Opportunity free. Haywood's 1312 South Oakley Ave- samples. American Monogram Co., Dept. 71, East remember, Orange. N. J. we're prepared to show you Facts. Write at once. Your nue, Chicago. name and address on a card will do. Address Dept. 861, Dollars yearly in your backyard. No mushroom dope. Make $25 to $50 week representing Clown' Famous Goodwear Chicago, Inc., 894 \Vest Adams, Chicago. Particulars free. Metz, 313 East 89th, New York. Philadelphia Hosiery, direct from mill-for men, women, Wonderful Invention eliminates all needles for Phono- writing Jokes, Epigrams and children. Every pair guaranteed. Prices that win. Free New, different, lasts for years. Earn$50 to $150 Weekly book "How to Start" tells the story. George Clews Com- graphs. Preserves records. Humorous Stories for Publication. We teach you how. Desk 27, 12,000,000 prospects. $15 to $30 daily, easy. Carry days American Institute of Humor. Office E, 414 Park Bldg., pany, Philadelphia, Pa. supply in Everplay, Desk 7D, McClurg Bldg., pocket. Cleveland, . We want Salesmen and Agents, either whole or side Chicago. Ohio line, to sell our low priced radio books to the trade. Ex- If you have adaptability to selling specialties, exclusive Wide -Awake Man to Take Charge of our local trade; $6 is on the Hush -A -Phone. This device cellent proposition for live wires. The E. I. Company, $8 a day steady; no experience territory available Publishers. 233 Fulton Street, New York City. to required; pay starts at is generally recognized by the largest concerns in the once; write today. American Products Co., 1829 American country, as superior to a phohe booth for voice privacy, Write and learn how to start profitable business with- Bldg., Cincinnati, O. office quiet, and telephoning in noisy places. Over a thou- out capital or experience. Silvering mirrors, refinishing headlights Auto Owners! Get your tires Free! Be our Factory sand banks have adopted it. It is without competition. auto tableware, plating. Outfit furnished. In- .Agent! Big spare time money-maker! Sample tires fur- Energetic men can make a life occupation of selling the ternationaL Laboratories, Dept. 25, 309 Fifth Ave., New in section. Office appliance, and York. nished. No capital or experience needed Write today. Hush -A -Phone their Armour Tire & Rubber Co., Dee& 282, Dayton, Ohio, telephone men particularly adapted. Write for proposi- Earn big money fast applying gold initials to autos. tion. Hush -A -Phone Corp., Room 1311, 19 Madison Every owner buys-$1.35 profit on $1.50 sale-particu- A Business of your Own. Make Sparkling Glass Name Avenue, New York City. and Number Plates, Medallions, Checkerboards, Signs. lars and samples free. Write quick. Lithogram Co., 120 Money -Making Plans Free! Wolverine Bureau, Dl. Dept. 19, East Orange, N. J. Big illustrated Book Free. E. Painter, 518, Wooster, O. .nnsnnusnnmm11sssmnsss,musnuuuunum, s, n, unun snmm 11,,,,,,,,,,,,1,s s,,,mnsnum, Muskegon, Michigan Only one sale a day means $200 per month. Five sales, Free Book-How to be Successful in Real Estate. Mae- $1,000 per month. Marvelous new adding machine. Re- Made donald Realty, San Diego, Calif. tails $15. Work equals $350 machine. Adds, subtracts, American Toys Cooperative Raise Capital for your business or patent by syndicating multiplies, divides automatically. Speedy, accurate, dur- Manufacturers on large scale, also homeworkers, wanted able, handsome. Five-year Offices, stores, fac- among investment bankers. Details free. Guardian Co., guarantee. to manufacture Metal Toys and Novelties, Barking Dogs, Bldg., New York. tories, garages, buy one to dozen. A fortune for live Wag -Tail Pups, Wild Animals, Automobiles, Indians, Fnfekerhnrker agents. Write quick for protected territory and free Cowboys, Baseball Players, Cannons, Toy Soldiers, Crow- Get Out of the Rut-$100 sufficient learn privilege tract - trial offers Lightning Calculator Co., Dept. W., Grand ing Roosters, Statues of Liberty, Miniature castings of Rapids, Mich. Capitol, Bathing Girl Souvenirs and others. Unlimited $60-$200 a week. Genuine Gold Letters for store possibilities. Guaranteed casting forms furnished manu- Chemistry windows. Easily applied. Free samples. Liberal offer facturers from $5.00 up, with complete outfit. No ex- to general agents. Metallic Letter Co., 441 B, North perience or machinery necessary. Hundreds made com- Learn Chemistry at Home. Dr. T. O'Conor Sloane, Clark, Chicago. plete per hour. We buy goods all year and pay high noted educator and scientific authority, will teach you. prices for finished goods. Cash on Delivery. Contract Our home study correspondence course fits you to take a Agents-Big returns, fast office seller; particulars and orders with manufacturers. ad on page of this samples free. One Dip Pen Co., 12 Daily Record Bldg.. placed Enormous business .on chemist. See Baltimore, waiting to be taken care of in 1929. Catalog and in- Chemicalas Institute ofNewu York, 66 W. 6 Broadway. Md. formation free. Correspondence invited only if you mean New York City. Rummage Sales make daily. We start you. business. Metal Cast Co., I ! issue.3 $50.00 Products it Boston Rd.. Price list Sr, Representatives wanted everywhere. Wholesale Distribu- New York. Established since 1912. Experimental Chemicals and Apparatus. ters, Dept. 32, 609 Division Street, Chicago. George Ott, 1218 Chestnut St., Reading, Pa. Chemicals C. P. standard prices and brands. Sunset Earn $ 10 daily silvering mirrors, plating and refinishing metalware, chandeliers, bedsteads, headlights. Outfits Automobiles Laboratory, Ellensburg, Wash. furnished. N. Deeie Laboratories, 1133 Broadway, New Experimenters! Three issues "Popular Chemistry"-25c. York. Build It Yourself-A Real Automobile that any handy Wright Laboratory, Dept. A, Caldwell. New Jersey. man or boy can build. A low -slung, speedy cycle car. Agents-Our soap and toilet article plan is a wonder; Power supplied by famous 21 H.P. Shaw Motor. Send Experimenters-We carry a complete supply of chemicals get our free sample case offer. Ho -Ro -Co., 2719 Dodder, stamp today for Descriptive Circulars or send 25e for and glassware for your chemical laboratory Catalogue 5c. St. Louis. Complete Book of Easy -To -Follow Plans. Shaw Mfg. Co., National Scientific Supply Co., 241 Pa. Ave., N.W., Wash- We start you without a dollar. Slaps, Extracts, Per- Dept. S.I.-1, Galesburg, Kansas. ington, D. C. m fumes, Toilet Goods. Experience unnecessary. Carnation u m m u s m n u u n,,,,,,,,,um,mmmssmsms,msss,,m, u,,mm u m i i i,uu, mmirusnuuunmusum I. C. S. Quantitative and Qualitative Analysis Labora- Co., Dept. 232, St. Louis. tory, chemicals and apparatus, for sale, cheap. Henry Agents-Make $10 to $20 daily selling the famous Battle Photos and War Relics Linde, 64 Garden St., RCoboken, N. J. duplicated, improved, cheapened. Nery-Ease Foot Comforts. Big demand. Over 100 per For Dens: Relics Collected from Europe's Battlefields. Products formulated, cent profit. Write today. Manhattan Products Co., Firearms, medals, helmets, etc. Ethical. Formulas: alcohol substitute, $.50; Waterless Hot 2520E Ave., New York. Illustrated catalogue and Water sBottle. $25.00í 2sf. sHarding, sL. B. Chicago. Bailey sample War photographs 25c. Lieut. Welch, 2117 s1029,, Men's Shirts. Easy to sell. Big demand everywhere. Regent Place, Brooklyn, N. Y. Make $15.00 daily. Undersell stores. Complete line. sssnssss,nss,,,,,,s,s,,,,,, ss,,,,,,,,s,,,,,,,,,,,,,,,,,,s s, s,ss,,,,,,,,,sss,,ms,s,,sm,ss,,,,,,, Courses Exclusive patterns. Free samples. Chicago Shirt Manu- facturers, 241 W. VanBuren, Factory 212. Chicago. Used correspondence courses bought and sold. Bargain Books catalogue 1,000 courses free. Students' Exchange, Dept. Use ou. kandseme Catalog; get orders from every home West 42d St.. New York. for Dr. Blair's famous home products. Liberal pay. Dr. Free-Upon request will send you my literature illus- 4, 47 Blair Laboratories, Dept. 535, Lynchburg, Va. trating the following books. Astrology, Character, Clair- Used correspondence courses of all schools sold, rented voyance, Concentration, Healing. Hypnotism, Magnetism, and exchanged. New 1924 catalogue free. (Courses Make $120 Weekly in Spare Time-Sell what the pub- Mediumship, Personal Magnetism, Personality, Physiog- bought). Lee Mountain, Pisgah, Alabama. lic wants-long distance radio receiving sets. Two sales nomy, Salesmanship, Seership, Success, Sex, Will, Yogi s ss,sssmssssms,smsmns '"" ,sssssssss''""'"sss,mss smssuss m weekly pays $120 profits. No big investment, no can- Philosophy, Gazing Crystals, etc. A. W. Martens, E. E. vassing. Sharpe of Colorado made $955 in one month. 6, Burlington, Iowa. Duplicating Devices Representatives wanted at once. This plan is sweeping Time, Labor and Money. the country-write today giving name of your county. "Lights, Colors, Tones and Nature's Finer Forces. "Modern Duplicators save Ozarks. 825 Washington Blvd., Chicago. including Vibrations; Odic -Auras; Electro-Magnetons; Gets Business. Reproduces Typewritten or penned letters, Cold -lights; Radio; Coming Inventions, 270 pages. Sat- Drawings, Lessons, Music, Menus, Bids, Notices, Speci- Sell Like Blazes! New, Instant Stain Remover. Fine isfaction Guaranteed; $2.00; Circulars Free. Stevens Re- fications, Maps or anything in one or more colors. Prints Premium every sale. Big profita. Outfit free. Write search Laboratories, 242 Powell Street, San Francisco, two per minute. Special Sale On. 30 Days' Free Trial. quiet. Christy, 35 Union, Newark, New York. Calif. $2.25 up. Booklet Free. B. J. Durkin -Reeves Co.. New Auto Accessory. Costs 6c. Retails $1.50. "Free Perpetual Motion, by Percy Verance. A history of the unnummumPittsburgh.,mPal,u,n,,,,,,,,,,n,,,,u,n,mnnsm,s mumuusussusm,mmus, ilmut Sample." Box 494 P, Hartford, Connecticut. efforts to discover same from earliest days to the present, $10 daily silvering mirrors, plating and refinishing together with a scientific discussion regarding the possi- For Advertisers bility its ultimate achievement. Profusely illustrated. lamps, reflectors, autos, beds, chandeliers by new method. of 24 words -355 Rural Weeklies $14.20. Ad -Meyer. Outfits furnished. Write Gunmetal Co., Ave. D, Decatur, 357 pages. Price postpaid, $2.00. The Enlightenment Ha IIL Specialty Co., 305 Fourth St., Edwardsville, Ill. 411,2mgIói tegiSsirl skeS ei ,ms,msss sole snmmssssums New Wonderful Seller. Over 100 per cent profit on every Diseases and Their Innate Healer. Book 50 cents. sale of Harper's Ten -Use Set. Needed in every home. Arthur Stevens, Wauseon, O. For Inventors Washes and dries windows, sweeps, scrubs, .mope, eta Hypnotism Astounds, Controls. Wants gratified. 25 Your Chemical problem solved and working process fur- Greatest year 'round seller. Write Harper Brush Works, easy Lessons $2.75. "Mindreading" (Any distance) nished for Five Dollars. Write me. W. Stedman Rich- 152 -2nd St., Fairfield, Iowa. Wonderful. Genuine. Guaranteed $2.75. "Book of ards, Consulting Chemist, Box 2402, Boston, Mass. Agents Coining Money Applying Monograms on automo- Wonders, Mysteries and Disclosures" $20.00 worth for Commercialize your Idea according to my Cooperative biles; you charge $1.50, profit $1.40; $15 daily easy; ex- $2.00. All three $5.00. Catalog free. Science Insti- Plan before patenting. Booklet Free. Ralph Burch, perience unnecessary; free samples. Worcester Monogram tute, &V119 -Belmont, Chicago. Patent Lawyer, Janitor Building, Washington, D. C. Co., Worcester, Mass. Sleep Qulekly Produced. Self or others. Infallible. working drawings for inventions, Priceless. Guaranteed Live 10c. Inventors-I prepare Agents: %bare to buy 12,000 articles Wholesale. $1.10. "How to Right" design machinery, solve technical problems. Patent draw- "Way to Win" 10e. Prof. Deprado, SV357 Oak, ings. H. Mech. Engineer, 150 Nassau St., Actually worth $50. Enclose stamp. Wholesale Supply Chicago. Wettstein, In., Valdosta, Ga. Net York. Psychology, Occultism, Hygiology, Stamps for lists. Patent Engineer Delemos, 296 Broadway, New York. Formulas, Processes, Trade-Secrets-Different, depend- Phipps, 1014 Belmont, Chicago. Patents, all countries, reasonable rates, terms, get book - able, Catalog free. D. Thinly Co., Washing- profitable. Oscar 2 Volumes by 1 t "How Do I Sell My Patent?" ton. D. C. Wilde-His life and Confessions, Frank Harris, $5.00. Free catalog of 2nd -hand book bar- We Develop your ideas into commercial shape for pre- Attention-Agents! Big Money -Making ¡proposition., gains. Nedwick's, 346 Clark St., North, Chicago, HL sentation to purchasers, making working models, drawings, Mozart Felt Rug, guaranteed made of entirely new felt. Hypnotism-Mind Reading, You "Can" Learn, complete experiments or tests. Courtesy, efficiency, secrecy and Rapid seller. 100% Profit. Sample prepaid $1.75. Write methods used, 25 "easy" Lessons, fully guaranteed $1.00 ample equipment; 30 years' experience. Ducorron-Rich today for full particulars. Maisley-Payne Mfg. Co., 20 S. Money Back? Yes! Henry S. Collins Co 32 Liberty Engineering Co., 504 Pacific Mutual Bldg., Lou Angeles. Sudbury St., Boston, Mass. Street, Hastings, Brooklyn, N. T. Cal. Science and Invention for April, 1924 1293

For Inventors (continued) Miscellaneous For Sale:-Patent on Switch for Street Railways. Motor- man throws switch while car is Ire motion. Chas. Strayer, 53% of Inventors lose their commercial rights through Get posted---Good prices paid for butterflies, insects. 127 Leslie St., Johnstown, Pa.

faulty applications and non -protective patents. Investigate See Sinclair display advertisement page 1262. unvw 11 m inm i m innunu n111mullmnll1111111111111111unuu umnmuuwullnuul,lm 111111,1w 11111,1nn before you apply for patent. See "Bulletin 7"-free. Patents Developing ideas and manufacturing our specialty. Ab- American Corporation, Barrister Building, Wash- solute years' Personal ington, D. C. satisfaction, 33 experience. write us. The Eagle Way & Stop Signal Co., 2016 Elm Et., Cincinnati, Inventors: We develop your invention to practical use; Ohio, Dept. A. Exchange Cheery Letters with new friends. Write make necessary drawings, models; expert engineering coun- Betty Lee Inc., 4254 Broadway, New York City. Stamp or Razor Blades Resharpened. Roseto Hanery, Boseto, appreciated. sel; before after Patent: also help market your invention. Pa. Investigate. (No attorneys or brokers.) Castoo-Guay Cheapest, best work. Engineers, Washington, D. C. Make and Sell delicious Confectionery. Pop Corn Exchange jolly letters with new friends. Lots fun! Balls, Crystalized or Calves. Formula $1.00. Charles Send stamp. Eva Moore, Box 908, Jacksonville, Fla, A. Lutz, York, Pa. Formulas , Hindu Psychology, Yogi, Personal Magnetism. Tite Se- Lonely Hearts, join our Club, be happy, correephnd- cret Sciences, Books and Courses. Large illustrated Pri- ence everywhere, many wealthy, descriptions, photos free; Moneymaking Books, Plans, Formulas. Catalogue Free. either Ideal Book Shop, 5501-E, North Robey, Chicago. vate Catalogue, with "How Realize Any Desire," 25e. sex, most successful method, 23 years' experience. Adams, 116 South Standard Corr. Club, Grayslake, Ill. ,,,,,, l 1.111 Michigan. Chicago. How? How Much? What? Where? Why? When? Who? For the Photographer Have you a question of any kind which needs answering? Correspondence Club-Many wealthy members every- Some of us can where. Fascinating particulars, 2e. Smith, Box 1167Y, Have you a Camera? probably answer ft no matter what it is. Write for free sample of our big Send us Denver, Colo. magazine, showing how to snake better pictures One Dollar. You will get your Dollar back or a and earn satisfactory answer promptly. Technical Associates, Dept. money. American Photography, 118 Camera House, Bos- D, Lonesome Make New Friends. Write Dolly Gray Club, ton, 17, Mass. P.O. Box 1478, Boston, Mass. Box 186K, Denver, Colo. Stamp appreciated. e1111,111111111o11uu111111111m111111,11111m11,1111.m1111111m11mmn111111,111m111111111111111111111111111111111111111111111 Draftsmen, Machinists-Shop and Office %Inks-Loose- Leaf. Sample Sheets 25c (Refunded). George Bollman, Leading Club, largest, most reliable for lonely people. Games and Entertainment 446 Elizabeth Street, Hazelwood, Pittsburgh, Pa. Established 19 years. Many wealthy members. Quick results. Mrs. Wrubel, Box 26, Oakland, Calif. Tricks, Puzzles, Jokes, Magical Apparatus, Plays. mnnnnnunu1111.111111111111111111111111111111111,1111,1111,11,11,1111111111111111II111111111111111111111111,11,11111111..111 Stage Supplies. Mind -Reading Acta and Sensational Old reliable, most successful matrimonial Flub in the Escapes. Sensi 10c for 160 -page illustrated 1922 profes- Motorcycles-Bicycles west. 1821 West Fairview, Spokane, Wash. sional catalogue. Oaks Magical Co., Dept. 549, Oshkosh, \Vis. Don't buy a Bicycle Motor Attachment until you get 50 Funny Parodies on Latest Songs, Yes, We Have No 111m11m11mmm11111111111111n1n11,11111111w1111uu1111mun1111111111,1111.111.111111111111u11m1111111111111113111111111111111m11 our catalogue and prices. Shaw Mfg. Co., Dept. 8, Galesburg, Kansas. Bananas To -day, Barney Goodie, The Girl Men Forget, etc., Health 25c. S. Collins Co., 197 Fulton Sheet, Brooklyn, N. T. mmmnnnnn11uunn1111.mlm11unuuuuu111111mmuam.11unumuuuunumuu1111mnuourni o Free to Men-Information of a scientific nature that has brought physical vigor and happiness to thousands. Novelties Phonographic Supplies No charge; no obligation. Enclose stamp for reply. C. I. Wood & Co., Colorado Springs, Colorado. Magic Goods, earns, books, novelties, tricks. Catalog free. Clifford Fenner, 2401 .Jefferson, Louisville, Ky. Build Your Phonograph. Quality pitonoparts. Famous Free-Stop using tobacco. . We will give free informa Serenado Motors. Also original Perfection Motors. Elec- lion how to conquer habit easily and permanently. Results Magic At Home-The rising cards -50c. Magic X-ray, tric Motors, tonearms, reproducers, amplifiers, ease mate- guaranteed. Anti -Tobacco League, Box M, Omaha, Neb. 50e. Look Behind, See around corners, 50e. All three rial, accessories. Free blueprints and building instruc-

i 1111111111,1 1 11 Coast nunummi mn11unu m 1nm n11nnu11nunuuu m nn 1111,,,,111111111111 mn11m11111mnnnn,1un1, for $1.00. Novelty Co., 3737 East Fifth St., Los tions. Big saving. Wonderful results. Prompt delivery. Angeles, Calif. Catalogue mailed for ten cents. Hoosier Mfg. & Supply Help Wanted ,umu11111111111n1111111111m111111111mnm11111111111111111111111m111111111111111111111111111111111111111111.111111111111111111111 Company, 321 Baldwin Block, Indianapolis, Indiana. We want Salesmen and Agents, either whole or side line to sell our low priced radio books to the trade. Ex- Patent Attorneys cellent proposition for live wires. The E. I. Company, Photoplays, Stories, Etc. Publishers, 273 Fulton Street, New York City. Patents. Send for free booklet. Highest references. Best results. Promptness assured. Send model or draw- Big money writing photoplays, stories, poems, song. Detectives Earn Big Money. Travel. Excellent oppor- ing for examination and opinion. Watson E. Coleman, Great Send for free copy America's greatest magazine for writ- tunity. demand everywhere. Experience unneces- Patent Attorney, 644 G Street, Washington, D. C. ers. Tells you how to write and sell. Writer's Digest, sary. Particulars free. Write, American Detective Sys- 637 tem, Inventors write me about patents. My fees payable Butler Bldg., Cincinnati. Ohio. 1971 Btne,iwpy, N. Y. monthly. Booklet free. Frank Fuller, Washington, Get posted-Good prices paid for butterflies, insects. D. C. $ $ $ For Ideas. Photoplay Plots Accepted. any form; See Sinclair display advertisement page 1262. revised, criticised, copyrighted, marketed. Advice free. Herbert Jenner, Patent Attorney and Mechanical Expert, Universal Scenario Corporation, 223 Security. Bldg., Railway Postal Clerks-Start $133 month. Railroad pass; 624 F Street, Washington, D. C. I report if patent ob- Santa Monica & Western, Hollywood, California. expenses paid; questions free. Columbus Institute, H-4, tainable and exact cost. Send for circular. Columbus, nnmm11mm11n11111mm1mnnun111111111m11m1111m11111111111m,,1,111,,,,,,,,,11n1l1111mn11mm11n1111mn,11111 Ohio. Lacey PatentSense. "The book the inventor keeps." Be a Detective; Excellent opportunity; good pay; travel. Free. See page 1266. Radio Write C. T. Ludwig, 1417 Westover Bldg., Kansas City, H. F. Lowenstein, Mo. Registered Patent Attorney, Radio Expert, 825 McLaehlen Building, Washington, D. C. Attention! 50 Vacuum Tube Hook -Ups. The greatest All men, women, boys, girls, 17 to 65, willing to accept "Inventors' of Vacuum Tube Circuits ever brought Government positions, $117-$250, or stationary, Guide" free on request; gives valuable in- collection under two traveling formation and advice for all who have original ideas or covers at such insignificant cost. These diagrams will be write Mr. Ozmert, 293 St. Louis, Mo., immediately. improvements. Frank Ledermann, Registered Attorney found in the great "Reece" catalogue which contains raw Silvering Mirrors, French plate. Easily learned, Im- and Engineer. 15-E Park Row, New York. materials and parts in a greater profusion than any other mense profita. Wear Excelsior in flans free. Mirror Works, "Inventor's Advisor," the valuable Patentbook with 139 catalogue. 15e stamps or coin will bring the. catalogue Springs, Mo. mechanical movements and sent free upon to you. Radio Specialty Company, 100 Park Place, New illustrations, York Earn $25 Weekly, spare time, writing for newspapers, request. AI. I. Labiner, Patent Attorney. 3 Park Row, City. magazines. Experience unnecessary; details free. Press New Yorke. Syndicate, 5665 St. Louis, Mo. Boys, don't overlook this! The ''Rasco" Baby Detec- Patents Procured; Trade Marks Registered-A com- tor. Greatest detector ever brought out with molded base. Men-Age 18-40, wanting Ry. Station office positions. prehensive, experienced, prompt service for the protec- month. Fully adjustable. See former advertisements in this pub- $115-$250 Free transportation, experience un- tion and development of your ideas. Preliminary advice lication or our catalogue. Detector Galena Crystal necessary. Baker, 78 St. with Write Supt., Wainwright, Louis. gladly furnished without charge. Booklet of information complete, 50e; the same. Detector with Radiocfte Crystal, Employment in South America. Classified Lists of Em- and form for disclosing idea free on request. Richard 75e, prepaid. Send for yours tray. Radio Specialty ployers $1. South America Information Bureau, Portland, B. Owen, 130 Owen Bldg., Washington, D. C. or 2278-T Co., 100 Park Place, New York City. Oregon. Woolworth Bldg., New York. Detectives Needed Everywhere, Work home or travel. Ex- Patents Procured. Send sketch or model today for ex- Radio Generators--500 Volt 100 Watt $28.50 each. perience unnecessary. Write, George Wagner, former amination, prompt report and advice. No charge for pre- Battery. Chargers $12.50-High Speed Motors, Motor - Government Detective, 1968 Broadway, N. Y. liminary advice. Write for free Booklet and blank form Generato Sets all sizes. Motor Specialties Co., Crofton, on which to disclose your idea. Highest references. Pa. Firemen, Brakemen, Baggagemen, Sleeping ear, train Promptness assured. Clarence A. O'Brien, Registered porters (colored). $140-$200. Experience unnecessary. Patent Lawyer, 921 Security Bank Building, directly 097 Railway Bureau, East St. Louis, Ill. Motors-G. E. 5/4 HP. $15.00-t,4 11T. $32.50-1 across the street from Patent Office, Washington, D. C. HP. $62.50. Generators 8 volt 10' amp $ 15. 32 volt Men, Women, Girls-18 up-Wanted for U. S. Govern- Monroe Miller, Ouray Bldg., Washington, D. C. Patent 500 watt $30. Other sizes. Low prices. Motor Special- ment Life Jobs. $1140 to $3000 year. Quick raise. Paid Attorney; Mechanical, Electrical Expert. Free Blue Book ties Co., Crofton, Pa. vacation. Pleasant, interesting work. Steady-no layoffs. gives candid advice. Write Immediately (today sure) for free list of positions The How and Why of Radio Apparatus, by H. W. obtainable. Franklin Institute, Dept. H24, Rochester, N. Y. Inventors-Send for form "Evidence of Conception" Secor, to be witnessed. Form, fee E. E. This newest book on radio matters fulfills a dis- o1u1111n1111111111111111111111111111111111um,n11n111111,1111111111111 1 1 1111111111m1111111 1 111 1 1111111m111 111, 1 1, 1 1 1 1 1 1 1 1 1 11111 signed and schedule, information free. Lancaster and Allwine, 242 Ouray tinct gap in wireless literature in that, while the treat- Bldg., Washington, D. C. ment is made as understandable and as free from mathe- Improved Made Toys matics as possible, it at the same time incorporates a Millions spent annually for ideas! Hundreds now wealth of technique and instruction for the Radio Amateur Wanted Manufacturers and Houseworkers to manufac- wanted! Patent yours and profit! Write today for Radio Designing Ex- Toys Wonderful opportunity. free books-tell how to protect yourself, how to invent, -the Operator-the Installation ansi ture Metal and Novelties. well as Birds, Animals, Wag ideas wanted, how we help you sell, etc, American Indus- pert-as teachers and students of the subject In Millions needed. In Whistling Wild A very broad field has been covered by the author, Tail Pups, Crowing Roosters, Automobiles, Baseball Play- tries, Inc., 212 Kresge Bldg., Washington, D. C. general. Indians, Toy Soldiers, Barking at the same time giving a great deal of information not ers, Statues of Liberty, The Patentome is free. A liberal education 1n patents. found in other teat books. If you are engaged in any Dogs; and 50 others. No experience or tools necessary. Anderson & Son, attorneys, estb. F. St., cost. 1865-637 branch of the Radio or allied arts at all you will surely Guaranteed casting forms with complete outfit, at N. W., Washington, D. C. need thin latest contribution to radio literature, which is From $3.50 up. We buy goods all year. Cash on de- or- Edward C. Sasnett, 531 McGill Building, Washington, destined to be found on every radio man's book shelf before livery. Higher price for finished goods. Contract long. A at the following list of chapters gives but ders placed. Send for catalog and information free. D. C., formerly a Principal Examiner in the United glan.;e Co., 342 East 145 Et., States Patent Office. a very scant Idea of the extensive and useful radio knowl- The Improved Metal Casting edge provided in its text. The Induction Coil; The Alter- New York. Patents-Let me assist you in obtaining your valid nating Current Transformer; Radio Transmitting Conden- nlwnuunannnnuuuuuuuunnumnnnnumwuvnul.nnnuuuniiinnnnuunuuuuuuu.m1111uuniuun Patent rights. Personal service. Promptness assured. sers; The Spark Gaps; Radio -Transmitting Inductances; George Van Den Berg, Barrister Bldg., Washington, D. C. Radio Receiving Tuners; Radio Receiving Condensers; De- Insects Wanted Get your own patents. Application blanks, complete tectors; Telephone Receivers; Radio Amplifiers; Construc- Get posted-Good prices paid for butterflies, insects. instructions $1. Cutting Bros., Campbell, Calif. tion of a Direct Reading Wavemeter and Decremeter; An- Measurement of See Sinclair display advertisement page 1262. M. P. Laughlin, Patents. Engineer -Attorney, 48 East tenna Construction; The Calculation and

1 1 1 1 1 1 11 1 1 1 111 1 1 1 1111111 1 1 111111111 1 1 1111111111111111 1 1 1111 1111111111,1 1 1111111 111111111111111 u u n n Inductances; Appendix very useful tables, cov- 1 1 containing mm n m 111111111111,1111111111111 41st Street, New York. ering all subjects treated in this very unusual book. This Instruction newest of Radio Works, cloth bound to Veil= de Luxe, Gold Stamped and Hand Sewed, has 160 pages. Size Learn Chemistry at Home. Dr. T. O'Conor Sloane, Patents of boo!:, 6x9 inches. The How and Why of Radio Appara- noted educator and scientific authority, will teach you. tus. Postpaid, $1.75. Experimenter Publishing Co., Book Our home study correspondence course fits you to take a I nventioisa Commercialized. Patented or unpatented. Dept., 53 Park Place, New York City. position as chemist. See our ad on page 1263 of this Write Adam Fisher Mfg. Co., 205, St. Louis, Mo, issue. Chemical Institute of New York, 66 W. Broadway, City. Canadian and foreign patents secured. Fine references. Attention! -50. Vacuum tube hook-ups. The greatest col- New York Reasonable ratos. Prompt, personal service. The Ramsay lection of vacuum tube circuits ever brought under two Correspondence Courses sold complete; one-third usual Co.. 273 Bank St., Ottawa, Canada. covers at such insignificant cost. These diagrams will be prices because slightly used; easy terms; money back found in the great "Rasco" catalog, which contains raw guarantee. All schools and subjects. Write for special M. P. Laughlin, Patents. Engineer -Attorney, 48 East materials and parts in a greater profusion than any other Free Catalog. Courses bought for cash. Economy Edu- 41st Street, New York catalog. 15e in stampa, or coin, will bring the catalog cator Service, 11202, West 49th St., New York. Unpatented ideas can be sold. I tell you how and help to you. Radio Specialty Co., 96-98 Park Place, N. Y. How to Make Rubber Stamps. 10e. Leo Lamberson, you make the sale. Particulars free. Write W. T. Greene, LaPorte, Ind. 808 Jenifer Building, Washington, D. C. Boys! Don't Overlook This. The "Rasco" Baby Detec- tor. Greatest detector ever brought out with molded base. Inventors! Write for new plan telling how and where Fully adjustable. See former advertisements to this pub- to sell commercially acceptable Inventions-whether Patented lication, or our catalog. Detector with Galena Crystal, Machinery and Tools or Unpatented. Results assured. W. J. Greene, 809 Jeni- complete, 50e, the same detector with Radiocite Crystal. fer Bldg., Washington, C. Block Machines and Molds. Cata- D. 75c prepaid. Send for yours today. Radio Specialty Com- Concrete Building pany, 96-98 Park Place, New York City. logue free. Concrete Machine Co., 305 South Third St., St. Louis, Mo. am111111m. uluumuuuuuunnuuuu11uun,1mnmm11uuuuu11mnmu11,1nnnnnuuuuuunnnnnnnlmnm 1111111m11u111111111111111111111111111,1111111111111,1nm111111111m111111 m11m1111u11n111111111111111111111111111 Patents for Sale Manufacturing Brush's Pad. No. 1,224,581 for $16,000.00. C. B. Relics Twyford, 817 Bailey St., Zanesville, Ohio. To o^der. Metal articles, simple, or complicated machin- Indian lore, exploration, discovery, get them all In e,y Sic lets tools, patterns Experiment I ng. T'arma Patent appl!cat ion blanks free. Patents for sale. lrehaesilogieel Reses.e.,. Six wonderful, illustrated num- Engineering Works, Brooklyn Station, Cleveland. O. Patent News -29, Washington, D. C. bers, 25e. Maas Publishers, Schenectady, N. Y. 1294 Science and Invention for April, 1924 Song Poems Wanted

Write the words for a song. We compose music. Our Chief of Staff wrote many big song -hits. Submit your FREE $soo°° song -poem to us at once. New York Melody Corp 412H Romax Bldg., New York. Poems wanted-Sell your song -verses for cash. Submit Mse. at once or write New Era Music Co., 145, St. Louis, Electrical Mo. Stammering >. , `1 Laboratories St-Stu-t-t-tering and Stammering cured at home. In- structive booklet free. d'alter McDonnell, 105 Potomac Rank Bldg., Washington, D. C.

Stamps and Coins Per Da - Stamps -50 varieties, Brazil, Peru. Cuba, etc., 10e. 50 different U. S., 25e, 1,000 hinges, 10c, 1,000 mixed, 40e, list free. C. Stegman, 5955 Cote Brilliante, St. Louis, MiasourL California Gold, quarter size, 27e; half -dollar size. 53e. Columbian nickel and catalogue, 10e. Norman and upward Shultz, Box 146. Colorado Spring, Colo. Stamps 100 All Different 3 cents. S. I. Quaker Stamp Is one I reason for the rapidly 'ompany, Toledo, O. growing popularity French Colonies Free --Pretty picture set, Native Chiefs, of the 'riges, 2e postage. Empire Stamp Company, 354 Lippin- Hotel Martinique. cott, Toronto, Canada. Another is 10111110111 m u 11111111111101111111111111111111100111111111111111111111111 the consistent m, 0 0 l 1001010100000000011000010011110 economy of the entire estab- Stamps for Collectors lishment. Here you may enjoy Approvals for more advanced senior collectors. Discounts a Club Breakfast at 45c., to 80% cat. Reference, International, 2117 Regent Pl., con- Brooklyn, N. Y. sisting of Fruit or Cereal, Bacon and Egg, and Rolls and Coffee Typewriters 111111'1"""' -Special Luncheon and Din- 9 ners of superior quality Laboratories All standard -makes. $IO up. Fully guaranteed. are also Free trial. Write for complete illustrated lists. Northwestern served at the most moderate Exchange, 320 Goethe St., Chicago. possible prices. Sent to Your Home Typewriters, All Makes.-Save one-half. Thoroughly re- No location can tailt in our factory by the famous "Young Process." Fully be possibly guaranteed. Free trial. We handle all standard makes. more convenient than that of Real actual -size, expensive units of electrical Cash or sold on easy terms. Write for Catalog. Young the Martinique. apparatus are mailed to you without extra Typewriter Co., Dept. 5054, Chicago, Ill. One block charge while learning. The illustration shows from the Pennsylvania Station one of the 9 new home -laboratory outfits. As Wanted (via enclosed subway) Nine fast as you have completed the work of one blocks from Grand Central- laboratory, another is sent, until yot' have mas- Detectives Earn Big Money. Work home or traveL - tered the entire field. You, therefore, advance Experience unnecessary. l'art.ieulars free. American one block from the greatest step by step, from simple electrical experiments Detective System, 1974 Broadway, N. Y. and best Shops of the City- to complicated, intricate, important practical half a dozen blocks from the work. Salesmen Wanted Opera and the leading Theatres Learn Electricity this New "Salesmen Wanted." Amazing Invention-almost hu- -and directly connected with man. The Little Draft -Man --a wonderful labor-saver, the Subway Quick Way automatically opens furnace or boiler while owner sleeps. to any part of the I'ays for itself In fuel saved. Simple, efficient, can be City you wish to reach. You can get the finest electrical training at Installed by anyone in five minutes. 100 per cent profit. home in your spare time. You need not leave Thousands being sold. $25 daily easily made. Act your job, your friends, your home. This won- quick. Address: Little Draft -Dian Co., Dept. C, Grand etsT without derful new home -laboratory training course in Rapids, Michigan. Practical Electricity brings this great, big tech- $700.00 Month for Salesmen-Am rounding out 1924 nical school to your very door-into your very sale;, force. Proposition is right. No competition. Vir- room. It develops ability, step by step, and gin territory to assign. My men averaged $5,000.00 to Hotel leads you to every reward the great field of $8,000.00 for past year. Buffalo representative averaged ee $700.00 month. I offer unusual opportunity to salesmen electricity can offer. who qualify. Write at once. Address C. R. Copped:, Salemnanager, National Advertising Service, Inc., P. 0. Just Like Going to School Box 60, LaGrange, Ind artinitfue Our large faculty of experts offer you a short A Salesman wanted in erm5 town or city within 25 miles of a broadcasting station to sell Radiogem, the l/1ffiliated with cut that combines theory and practice, eliminat- complete radio receiving ,,lfiiel .ÁZ`illpin The is so set that retails for $2.50. With ing all the non -essentials. plan Radiogem there is nothing else to buy-the outfit in- simple-so logical-so carefully arranged, and cludes the Radiogem receiving apparatus, 1,000 -ohm Broadway-32 also so interesting, that in a surprisingly short phone, and aerial outfit. The cheapest radio outfit on Ito 33Sts time you will have made yourself a master of the market-yet as practical as the most expensive. Big money to the right men. Send $1.35 for sample outfit. NEW YORK technical electricity, The Radiogem Corp., 66E West Broadway, N. Y. City. Al E.Singleton. cif/tanager. Earn Big Pay Sell coal In carload lots. Side or main line. Experience unnecessary. Earn Week's Pay in an Hour. Washington Billions of dollars are invested in this great Coal Company, 704 Coal Exchange Building, Armour Sta- industry. Trained experts are in demand and tion, Chicago. handsome salaries are paid. You can easily Specialty Salesmen! New Ford Money Maker. Riretin master the work through our personal coaching Fil -O -Meter tills gas tank without lifting cushion. Gauge and "home -laboratory" plan so that you can shows gasoline measurement. Sells on sight, $5.00 retail, FRONTIER SPECIA lilg profits. step immediately into the industrial field.. WE Write today for details. Sample sent on 10 FAMOUSNG ASSIST ALL OUR GRADUATES TO POSI- Day Money -Back Trial. Weight two pounds. A. J. TIONS WITH THE LEADING ELEC- Eiraten Company, 119 Kirstin Bldg., Escanaba, Michigan, SWI TRICAL FIRMS IN THE UNITED ír1 STATES. Short Stories, Manuscripts Wanted NEW 1924 model, blue steel, Earn $25 Weekly Spare Time writing for newspapers, Apparatus magazines. 6 -shot famous Frontier Free-Electrical Experience unnecessary; detalla free. Presa Special, swing-out hand -ejector Syndicate, 566 St. Louis, DIo, In addition to the free use of our 9 large revolver with 5 -inch barrel. Im- experimental boards we will give you Stories, Poems, Descriptive ported from Spain, the equal of electrical Articles. Plays, etc., are any $35 model, and specially priced materials and apparatus needed for experi- wanted for publication. Submit Diss. or write all Bureau. Literary for limited time to add new customers. mental work with the 9 outfits, absolutely free 165 Hannibal, Mo. LOW PRICE SPECIAL in32,32-',O, and ship it with the first laboratory shipment. mum ,,,01011111111,111011111111.11,1,11111111,11111111111111111111110111111111111011111011111111111111111,111111111111111111 or 38 cal., "nr No.356 $12.25, No materials to be purchased by you. We EXTRA SPECIAL our No. 260A latest 1924 needed. Wireless model of blue steel. Each revolver has passed strict furnish everything Government test. 32 -cal, -6 -shot . $14.95 The How and Why of Radio Apparatus, by H. W. Secor, 32-20 or 38 cal. -6 -shot $15.45 E. E. This newest EXTENSION DIVISION book on radio matters fulfills a distinct gap in wireless literature in that, while the treat- 20 -SHOT "PANTHER ment is made as understandable and as free from mathematics as possible, it at the same time incorporates a RAPID FIRE AUTOMATIC ENGINEERING wealth of technique and instruction for the Radio Amateur IMITED quantity of brand new, 32 cal. 5CHLOF -the Radio Operator-the Installation and Designing Ex- L"Panthers." 10 shots with extra maga-aaP$845 of Miiwaukete pert-au well as teachers and students of the subject in nine making 20 rapid fire shots. Special at general. A very broad field has been covered by the author, Above guns all shoot any standard American cartridge, 415 Marshall Street Milwaukee, Wis. at the same time giving a great deal of information not PAY POSTMAN ON DELIVERY plus postage. found in other text books. If you are engaged in any Money back promptly if not satisfied. branch of the Radio or allied arts at all you will surely CONSUMERS CO., Dept-CIAG 1265 Broadway, N.Y. Extension -Division, need this latest contribution to radio literature, which is destined to be found on every radio man's book shelf before School of Engineering, long. A glance at the following list of chapters gives but Dept. S.1. -H.424, 415 Marshall St., Milwaukee, Wis. a very scant idea of the extensive and useful radio knowl- Short -Cut to the Electrical Pro- edge provided in its text. The Induction Coil; The Alter- Please send me "The nating Current Transformer; fession" (just off the press) and full details of your Radio Transmitting Conden- "new wonderful laboratory method" of home -study in sers; The Spark Gaps; Radio -Transmitting Inductances; Practical Electricity. This request obligates me in no Radio Receiving Tuners; Radio Receiving Condensers; De- tectors; Telephone Receivers; Radio Amplifiers; Construc- tion of a Direct Reading Wavemeter and Decremeter; An- tenna Construction; The Calculation and Measurement of !!.cis, Mink, Muskrats and Name Inductances; Appendix containing very useful tables, cov- other animals fn large ering all subjects treated in this very unusual book. This Catch Fish, bers SURE-with our new newest of Radio Works, cloth bound in Vellum de Luxe. folding, galvanized Steel Wire Traps. They catch Address Gold Stamped and Hand Sewed, has 160 pages. Size of them like a fly trap catches flies. Write for our FREE TRAP book, 6x9 inches. The How and Why of Radio Appara- offer, bargain catalog of Fishermen's Supplies and booklet tus. Postpaid, $1.75. Experimenter Publishing Co., Book on best lure known for catching all kinds of fish. Agts.wtd, State Dept., 53 Park Place, New York City. Town WALTON SUPPLY CO., Dept. 43 , SG Louis, Mo. Science and Invention for April, 1924 1295

,,,,,,,,,,e,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,11,1,,,,11111,,,,,,,,e1,,,,,,,,,,,,,,, The Electrical Maga- //I/III!/t/ umemtïmllttllt111111i(rttNilllllll/Ifffe zine for Everybody a1 ForSaleAt All NewsStands . Q)er 3.c,S I00 25e. the Copy ate- 1eCxtl: ons $2.50 a Year Canada and Foreign a a Year $3.00 ELECTRIC MUSIC. HOW TO MAKE THE STACCATONE See Page 248 Now Greatly Enlarged One-third More Text and Reading Matter than Heretofore

This Magazine is Edited by H. GERNSBACK Also Editor nl Radio News anti Science & Invention 11f/////////l1flNUfffltllltlllilll111llftlglfRl41U1111,1)31t\UUUl\\\.A\l\\\\\\l\\\.\

,,,,,,,,,,,,11,,11,,,,,,,,,,,,1,,,,,,,,,,1,,,,,1,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,i Practical PRIZES Everda This magazine offers a number of prizes, as follows: Our $50.00 Prize Contest for Junior Electrics Everbodv and Electrical Experimen- for Electricians ters includes as its elements simplicity, as great a degree of novelty as possible. kind ever con- and practicability. p\CTICAL ELECTRICS is probably the most novel magazine of its Also a new prize contest giving four ceived. It is personally edited by H. Gernsback, editor of SCIENCE & INVENTION prizes amounting to $37.50 for the best and RADIO NEWS. Mr. Gernsback, who founded the old `Modern Electrics as well account of an odd electrical experience. tke "Electrical Experimenter," knows thoroughly what his readers want and have wanted $3,00 for the best article on Elec- eclipses the Tricks, the new department. for many years. PRACTICAL ELECTRICS, the 100% electrical magazine, $3.00 for the best "short-circuit," the best that was in "Modern Electrics" and "Electrical Experimenter." semi -humorous department. not keep abreast with In addition to this, the magazine pays Electricity covers such a tremendous field that the man who does high prices for all electrical experiments, it does himself a great injustice. PRACTICAL ELECTRICS covers that field from every electrical articles, etc. See current issue angle. It is written in plain every -day language that all can understand. It portrays the for full details. entire electrical development of the month faithfully in non -technical language. It caters to everyone interested in electricity, be he a layman, an experimenter, an electrician or an M111.11,1111111111111111111111111111111111111111111Z1111111111111101111111.11.11111111111111111111111111111111 engineer-each will find in this magazine a department for himself and plenty more. The April issue now on the news-stands contains 64 pages, over 100 different articles and over 150 illustrations, with an artistic cover in three colors. Professor T. O'Conor Sloane, Ph.D., is associate editor of the magazine. INTERESTING ARTICLES TO APPEAR The issue contains articles by some of the greatest electrical writers, workers and IN APRIL ISSUE OF "PRAC- students. The magazine will prove a revelation to any one interested in electricity. TICAL ELECTRICS" Every issue besides its many other features contains the following departments: Odd Telephones By Clyde J. Fitch Things "Elec-Tricks" Analogies and Others "New Electric" By T. O'Conor Sloane, Ph.D. "Experimental Electrics" "Motor Electrics" Detection of Icebergs Austrian Rival of Franklin "Electrical Digest" "Short Circuits" Infra Red Light Telephony "Junior Electrician" "How and Why" (Questions and Answers.) By Jacques Boyer (Paris =_ Correspondent) Make all checks payable to: Electrics Cn." Building a Thermogalvanometer "Practical Electric Oil Feed for House Furnace By George E. McVicker Farm Windmill Electric Plant Hot -Wire Ammeter S.hl.,t-21 Lighter uu,,,,,,u,,,,,,,,,,,,,,,,,,,,,.F Send for SPECIAL OFFER Gentlemen: Although your regular price is $2.50 per year, PRACTICAL ELECTRICS FREE you will accept my subscription at $2.00 per year (Canada and foreign, $2.50). I enclose COMPANY the money herewith and I have written my Sample COPY name and address in margin below. 53 Park Place, New York Name Address 1296 Science and Invention for flpril, 1924

Results from the Adaptation of the "Power Within" to the Stress of Environment

T IS a question of relativity. Disease is the result of supernor- mal stress or of subnormal resistance. When the nerve, over which the "power within" sends its adaptative impulses to the cells, is impinged by a subluxated vertebra, the "power within" cannot adapt the organism to the stress of environment and we become sick. To regain health it is necessary to turn on the power of adaptation-resistance. To turn on the power, the impingement must be removed from the nerve, in order that it may again function normally. To remove the impingement the misaligned vertebra must be adjusted, and this adjustment of the vertebra is the work of the chiro- practor. By giving Chiropractic a fair trial millions have recovered their health.

Write for information regarding Chiro- practors or Schools to the UNIVERSAL CHIROPRACTORS' ASSOCIATION DEFINITION rrrhe practice of Chiropractic fI consists of the palpation and adjustment, with the hands, Davenport, Iowa, of the movable segmenta of the spinal column to normal position for the purpose of releas- U.S.A. ing the prisoned impulse.

A11 Rights Reserved NORMAN L. SCHNEE CURTIS GREEN A. K. MARABLE Los Angeles, Cal. Des Moines. la. Jacksonville, F a. I started working "Before I enrolled with "I was a railroad clerk. as a Topographic Drafts- the Columbia School of I worked at the course all man with the Iowa Divi- Drafting I did not know my spare time. I was sion of the Bell Tele- very much about drafting drafting in the department phone Ca. making City surprised myself to of a house -planning cor- Street and Country road keno how easily and how poration 8 months before maps. That was when I quickly I had worked up I graduated. 1 was with had completed only the to designing machinery. the present company at first eleven lessons. but Only a few months' study $35.02 per week. when they helped me in secur- with your school has won my wages were raised ing the position. The me this position." (Mr. to $40. I are a Chief Draftsman got me Marable makes about $200 "BOOSTER." a $10 raise." monthly.) 'I made a map for a mining firm tivhích took me hree days to draw and I received $275" MR. BRAUND was earning $2 per day as a skilled laborer. The future was dismal. Then the BOOK - LESS drafting course caught his eye. He saw in it the Ghost of a Chance. He enrolled. The instructor watched his work very closely and advised him to take Topographic Drafting. A few months later Mr. Braund was earning $200 to $250 monthly. Today he sits in his own private office. He is a successful business man. Mr. Braund was a good Topographic LETTER "Feeling deeply grate- Draftsman months before he got his ful for your alvlce to me to take up the Diploma. Nearly all Columbia-trained at u d y of Topographic Drafting. I want to let men earn big money before finishing. you know by writing how much I appreciate Thousands of Draftsmen are needed. this advice and to tell you of the success I have had. When start- Big corporations building projects in ing your course I wa, working for $2 per das far-off U. S. possessions, or Surveying as a skilled laborer tt the government. Nov expeditions into the uncharted wilder- I am malting around 0200 to $250 a monts nesses use our trained men. They ask .-I think that the future In my line of for them. We supply many. U. S. irk is very goal. ...I a friend who is a 'lug Engineer that Government Draftsmen get $2,500 to . eil as a Draftsman -w yours ago and to $4,000 per year. $12 per day and an 'CINC $75 A DAY. interesting life in big business is what we train you for. None of our graduates ever see a book while being trained. Each one starts right out at practical drafting. You are prepared the EASIEST, SHORTEST and BEST WAY. -there are no confusing text books -you start right in drafting -you need no previous education -only common arithmetic is necessary MEN I HAVE MADE No. 1-11e earned a bare living. There is always an opening somewhere at good The U. S. Government needs men constantly. His chance of advancement was not even hopeful. I gave him personal pay for you just as soon as you have advanced Often you get a chance to earn big money and attention. Within a few months I far enough. After 3 to 4 months of training also travel luxuriously. trained him to make big money. To- day he is a DOLLAR -MAKING hundreds of our men get positions. SUCCESS. He Is .John .J. Braun,. Roy C. Claflin, President Write to Me About Yourself. Columbia School of ['rafting 14TH AT T. ST., N .. WASHING A LIST OF SUCCESSES COLUMBIA SCHOOL OF DRAFTING, THOMAS H. ENGLISH, Wilkinsburg, Pa., Dept. D-24, Washington, D. C. went to work at $135 per month for West- Without obligation Please v991 Die ,'our interesting rats],. inghouse Co, on graduating. Now nearer the opportunities In Drafting, s Free ropy of your studnu iap- $200 mark. TIIE COMII'ASS, and an enrollment blank. JOSEF L. FREI, Chicago, Ill., after 22 les- Name sons got position as Draftsman with West- Address ern Electric Co. GEO. W. HICKMAN, Jr., Mohnton, Pa., got City Instruments and full pro- a salary of $152 his first month as drafts- Stete fessional drafting outfits are man for factory. supplied as part of the course. John Lutherway, W. Va. A. G. Hughes, Kentucky. "I learned more about pho- E. D. Blaut, Ohio. C. M. Cole, Washington. "I went out two days last tography from your first "On Christmas I made a "I have been able to buy my week on home portrait work twenty lessons than from the family portrait and handled house and lot from the sale and made $97.00. I very 5 years I tried to train my- the job so professionally that of pictures alone. I sold the often sell an enlargement for self from photographic I was paid more than the pictures of a recent flood for $10.00." books." price of your entire course." $100.00." THESE MEN MAKE BIG MONEY TAKING PICTURES Like hundreds of others, you can train at home and establish a business of your own which will make you independent.

TREMENDOUS, big paying opportunities are open for Train With a Leading Photographer every man who knows Modern Photography. Magazine and newspaper publishers buy thousands of photographs a year. As Director of the International Studios, Inc., I know Thousands of manufacturers use pictures in taking orders for just the kind of training you need to be successful in this their products. Every home wants portraits. Photography is line of business. I show you how to do the actual work a business running into millions of dollars annually. Yet there yourself.. Anyone can learn to take good pictures. Then is an actual scarcity of trained men. it is only a step to modern professional work. If you want to get big prices, you must know how to take pictures that Easy to Earn $3,000 to $10,000 a Year sell. I want to show you letters from hundreds of men who are becoming independent through this fascinating profession. Do I Guarantee to Satisfy You you know that right now there are over 35,000 I am absolutely positive that I can train you splendid locations waiting for ambitious men to QUALIFY to make big money. Therefore I guarantee under for jobs like these- start their own business? Hundreds of big paying Studio Director bond to return every cent of your tuition if you are also open. During spare time alone I Newspaper not thoroughly satisfied with my training. positions are Photographer while taking this course you can make $75.00 a Aerial Photographer Commercial week. Others are doing it. It makes no difference Photographer Professional View Camera: whether you live in the country, small town or city. Studio Manager Portrait FREE Now Photographer Motion Picture I give every student a splendid big size Profes- No Experience Necessary Operator Architectural sional View Camera, absolutely free. With it you Many of my most succssful students will tell you Photographer do modern professional work right from the start that it makes no difference if you never took a Expert Retoucher Landscape -also charge modern prices. picture in your life before. My simple, easy, prac- Photographer tical training will enable you to have a successful business in a few months. You need only a common school Mail Coupon for Unusual Offer education to succeed. For a short time I am making a most unusual proposition ...... f...i..IM,..` to ambitious men who like to take pictures. This offer will I1, % SEND be withdrawn without notice. So mail coupon today. I % yO also send you on how to make big money Lr 4r XS . will full information t THIS in modern photography including a complete description of 9 P °6 " g 92r a . av i the free camera. ss ary ° ß?, r 51NOW 1t4Peç` e 0 "Os: s cb lC H. R. VANT, Director, aari " ¡ .ree S4ac r+rPs` C O °Opbr s9 International Studios, Inc. °t°4,. Dept. 7454 phJ, 3601 Michigan Avenue, Chicago, U. S. A.