eElectrica Experimenter www.americanradiohistory.com -: -. 7RAD INSULATORS 1,000 TO 1,000,000 VOLTS Employed by U. S. NAVY and all the Commercial Wireless REG. U.S. PAT. OFF. & FOREIGN COUNTRIES- Telegraph Companies INSULATION LOUIS STEINBERGER'S PATENTS 4 '0 -1-nvvt-wwd 47,02 isos rilittfiri$44 4 44. 4517 // íi,. % %rL uvi ir ® 'Tv Tvf,%.oi.: 655.i a2ti_ ,r's77 %/%/,r/,i/.',irvi 17:: ,4 411\k'' s, wa4 77.. n /i\S2 \VN 71:ní SOLE MANUFACTURERS .:;., T= ,/ 66 -76 Front St. BROOKLYN, N. Y. 60-72 Washington St. AMERICA HERE IT IS Are You Losing the Weak Signals ? AI:F the receivers y..11 n'e merely high-wound telephone receivers - whirh bring in ordinary. sig- nals clearly enough, but miss The ALBANY altogether the weak, long - di - tance ones' Combination DETECTOR Or are they real wireless Polished hard rubber base, I, ceivers - sensitive enough to bring in ct en the ex- inch hex. brass standards, one tremely weak signals? pivoted. Five holes in large cup. you have actually Until 5/8 inch diameter. tried Brandt, Receivers you Small cup ,xill never know how many Noval cat whisker attachment signals you may now be fail- ! Saprai \víth each instrument receive of in- ing to because PRICES ,fticient receivers. To-day-write for our new CATALOG E, containing im- Lacquered brass $2.00 They are designed, made portant information about Polished nickel 2.50 and used solely as wireless radio as well as receivers. full lb. receivers. They have Sensi- intormation about our sev- Postage extra -weight t tiveness which is surprising eral type. of Head Sets -Tone which is ab'olutely Enclose '!e. stamp. We are still selling our niforn - Lightness tvhich permits their use for hours C. BRANDES for without causing fatigue. Com- No. 102 Condenser $2.50 parison with any other make Wireless Receiver Specialists Iostage extra. Weight 2 lbs. will prove these points of su- Room 874 Order yours to -day, as this periority to you. 32 Union Square, New York, N.Y. offer will not last long. Send for our circular 3 -G. Brandes Wireless Head Sets MAGUIRE & SHOTTON 814 LANCASTER ST. ALBANY. N. Y. You benefit by ,rent inn ingwww.americanradiohistory.com "The Electrical Experimenter" when writ,, g to advertisers. November, 1915 THE ELECTRICAL EXPERIMENTER DUCK'S No. 9-325-PAGE Electrical and Wireless Catalog Ready on October 20th 40 more pages of wire- less instruments at more attractive prices than ever. Also many new items in electrical supplies at substantial reductions in price. What This Big Catalog Contains 160 pp. Wireless Apparatus for Commercial and Ex- perimental use. 10 pp. Raw Material, 5 pp. Transformers, 8 pp. Storage Batteries 15 pp. Telegraph Insts., 421, Iotors and Dyna- mos, 10 pp. Miniature Lamps, 8 pp. Flashlights, 5 pp. Massage Vibrators, 10 pp. Miniature Rail- ways, 5 pp. Lighting Plants, 10 pp. Ammeters and Volt- meters, 25 pp. Electrical and Me- chanical Books, 12 pp. Telephone Equip- ment, 10 pp. Auto Accessories, 13 pp. Victrolas, on our Easy Payment Purchase Plan (No Down Pay- ment), 30 pp. General Electrical Supplies. TIIIS UNRIVALED CATALOG MAILED TO ANYONE UPON RECEIPT OF 8 CTS. IN STAMPS or coin, which may be deducted on f_rst dollar purchase. Great cost of catalog and low prices prohibit distribution otherwise. 230 eet THE WILLIAM B. DUCK CO., TOLEDO, OHIO www.americanradiohistory.com 306 THE ELECTRICAL EXPERIMENTER November, 1915 ifCLOPEDIACYCLOPEDICYCLOPEDIA CYCLOPEDIA CYCLOPEDIA CYCLOPDIA V CYCLOPEDIA APPLIED APPLIED APPLIED APPLIED APPLIED APPLIED APPLIED CTRICITY RIQTY CTRICITY !CTRlCITY aECTRICf I Y ELECTRICITY UnmaTY vohwt vOL.1T VOL.III VOL.IT v4.Y VOL.y! ELEM. World's Greatest Electrical Librar? SENT FREE FOR EXAMINATION Send the coupon today -now -for your free -for -examination set of the world's greatest elec- trical library. The new 1915 edition. just off the press, is recognized by big men in the electrical field as the most practical work of its kind ever published. Covers completely the generation and use of electricity for power, light, transportation and communication, including the construction and operation of dynamos and motors, central station engineering and telephone work. as well as wireless telegraphy and telephony and land and submarine telegraphy. Particularly helpful in its exhaustive treatment of electrical "troubles" and their remedies, Electrical Engineers earn from $150 to $250 a month. AMER Earn $150 to $250 a month The work is pleasant -the hours short. These great books will fit you, in your spare time. to enter this fascinating, well -paid work. No previous experience necessary. Cyclopedia of Applied Electricity New 1915 edition contains 3,500 pages, 7xto inches; 3,000 illustrations, ful 1 page plates. diagrams, etc.; hundreds of valuable tables and formulas; care - fu lly cross- indexed for quick, easy reference. The books are substantially bound What These Books Cover in half red morocco, gold stamped. and are printed in large, clear type on special Elements of Electricity -Electrical Measurements Underwriter's qu ality paper. Electrical Requirements - The- ory, Calculation, Design a n d Upon receipt of the coupon below the complete seven Construction of Direct Current 50e a week volumes, not a sample volume, will be sent, express Generators and Motors -Types of Generators and Motors -Man- prepaid, for seven days' free examination; returnable at our expense if they fail agement of Electrical Machinery -Electric Lighting - Alternating to meet with your expectations. If you keep them, pay $2 seven days after Current Machinery -Power Trans- receipt and then $2 a month -50c. a week -until you have paid the special intro- mission- Electric RaiIways- Self= Propelled R a í I w a y Cars- ductory price of $19.80, saving $15.20, as the regular price of this new and Trackless Trolleys -Power Sta- tions- Switchboards and Switch - enlarged edition is $35.00. As this offer is for immediate acceptance only, fill ing-Storage Batteries - Applied in and mail the coupon to -day. 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They stand ready to solve your perplexing problems, $2 within seven days and $2 a month until $19.80 has been to offer suggestions, to point out the things you should paid, when $35 books and $12 consulting membership will be avoid. Absolutely no limit to their assistance -ask as mine. Otherwise will notify you and hold books subject many questions as you wish for a whole year. This service to your order. Title not to pass until fully paid. alone will be worth more to you than the entire cost of Elec. Expel-, 11 -15. the books. NAME Don't wait. This means $15.20 saved if you act now. ADDRESS Remember, you take no chances whatever -it costs nothing to inspect and you are nothing out if you do not care to As I have liad no previous dealings with you, I refer buy. This offer may mean your success, so mail the coupon you to to -day-now -before you turn the page. American Technical Society, Chicago, U. S. A. Yon benefit by mentioning "The Electrical Experimenter" when writing to advertisers. www.americanradiohistory.com The EIlectrncaIl Experimenter Published by Experimenter Publishing Company, Inc. (II. Gernsback, President; S. Gernsback, Treasurer; M. Hymes, Secretary), 238 Fulton St., New York Vol. III Whole No. 31 CONTENTS FOR NOVEMBER, 1915 No. 7 FRONT COVER -"THE RADIUM DESTROYER" ILLUMINATED STEAM CURTAIN GIVES WONDERFUL EF- From a Painting by Thomas II, Wrenn FECT AT NIGHT 332 THE ELECTRO. MAGNETIC GUN ANI) ITS POSSIBILITIES 309 ELECTRICITY AND THE TWENTIETH CENTURY DENTIST 332 BARON MUNCHHAUSEN'S NEW SCIENTIFIC ADVENTURES "TIIE CONSTRUCTOR" DEPARTMENT 333 By Hugo Gernsback 312 HOW TO BUILD A DICTAPIIONE DESK SET 333 WARFARE OF THE FUTURE 315 CONSTRUCTION OF AN INDUCTIVE TUNER WHEN THE LIGHTS WENT OUT ON THE "BELLA" 316 By Milton B. Sleeper (Conclusion) 334 -335 WHAT THE HOUSEWIFE SHOULD KNOW ABOUT ELEC- "RADIO" DEPARTMENT . 337 TRICITY 317 THE AMATEUR RADIO STATION \VI -IICII AIDED UNCLE SOMETHING ABOUT SELENIUM 318 -320 SAM By Charles E. Apgar 337 -338 WIRELESS TELEPHONY NOW FROM WASHINGTON TO A POCKET WIRELESS SET 338 HONOLULU 321 A MACHINE THAT CAPTURES AND HOLDS WIRELESS PHOTOGRAPHING SOUND WAVES ELECTRICALLY.........322 -323 TALK 339 DANIELS NAMES NAVAL BOARD 323 HOW WIRELESS WAVES TRAVEL AROUND THE EARTH'S SOME NEW X -RAY APPARATUS . 324 CURVATURE 340 READING ELECTRIC METERS WITH A CAMERA 326 HOW TO BUILD A WAVE METER By Samuel Cohen 341 MISHAPS ATTEND USE OF WIRELESS ON AEROPLANES... 326 "HOW-TO-MAKE-IT" DEPARTMENT 344 MASSIVE ELECTRIC GENERATOR HOLDS AUTOMOBILE 327 "WRINKLES, RECIPES AND FORMULAS" MIND -READING DOG IS A PUZZLE TO SCIENTISTS 327 Edited by S. Gernsback 347 HIGH FREQUENCY CURRENTS AND APPARATUS "WITII THE AMATEURS" 348 -349 By H.