The ELECTRICAL EXPERIMENTER Is for Sale at All Neumslands Lo the United States ELECTRICAL EXPERIMENTER

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REG. U.S. PAT. OFU AERIAL MONO-FLYER OF THE FUTURE SEE PAGE 228

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X46 °-_° to X100 °_° a Week Go after some real money. Qualify for one of the thousands of splendid positions open. All you need to start is a few months snappy, practical instruction from a competent engineer. Come to me -NOW. I'll give you my personal care to ensure rapid and efficient progress. My course is intensely practical. It is highly condensed, simplified, up -to -date and complete. I am so sure you will make a splendid success in this study, that I will Guarantee Under Bond to return to you every cent paid for tuition, if you are not entirely satisfied when you receive your Electrician's Certificate granted you as a graduate of my school. FREE Lessons and Outfit FREE Send me the Free Outfit Coupon at once. Do it now! For a limited period I am making a slashing cut in the cost of tuition, and giving each new student a grand outfit of Electrical Tools, Material and Instruments -in addition-Abso- lutely Free. I will also send you -free and fully prepaid -Proof Lessons to show you how easily you can be trained at home to enter this great profession, by means of my new, revised and original system of mail instruction.

Use this "Free Outfit" Coupon ACT PROMPTLY CHIEF ENG. COOKE, Dept. 28 Get the full benefit of this great offer. Send the 441 Cass St., CHICAGO, ILL. Coupon or a postal for free information without delay. Do it before my free offers and guarantee are withdrawn. SIR: Send at once -fully prepaid and entirely free -complete now- particulars of your great offer for this month. CHIEF ENGINEER COOKE Name Chicago Engineering Works Address DEPT. 28 441 Cass Street CHICAGO, ILL.

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www.americanradiohistory.com A August, 1918 ELECTRICAL EXPERIMENTER 217

BOT RADIO AND MORSE Your Government is calling for experienced wireless operators and telegraphers. Many schools have been opened where special instruction is given qualifying young men to accept such positions in the army and navy with advanced rank and increased pay. You Can Learn at Home in Your Spare Time Combination Wireless- Telegraphy OUTFIT will soon make you an accomplished operator. Teaches Light and Sound Signals, both Radio and Morse. Outfit consists of exceptionally fine Telegraph Key, Buzzer, 3 Binding' Posts, Lamp, Lamp Socket and Control Switch -all mounted on a highly finished base. Two outfits can be operated at considerable distance apart for sending and receiving practice. PRICE OF COMPLETE OUTFIT $2 WITH WIRING DIAGRAM, CHART AND FULL. INSTRUCTIONS T 50 Shipped to You Anywhere, All Charges Prepaid This Same Outfit Without Lamp $2.00 Or your dealer can secure it for you. Order to -day. Descriptive circular and catalog of celebrated Knapp Motors and Electrical Specialties from 10c up mailed free on request. KNAPP ELECTRIC & NOVELTY CO., 523 W. 51st St., New York City

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www.americanradiohistory.com 218...... ELECTRICAL...... EXPERIMENTER August, 1918 EXPERIMENTERS! ATTENTION!! "ELECTRO" LOUD -TALKER We present herewith two little instruments for which enamel wire for five ohms, standard with our Detectiphone. we have had a long and persistent demand. This instrument -works best on four dry cells, and par- This outfit has been gotten up solely for the Experi- ticular attention is called to the fact that in order to work, menter and for this reason we are selling it "Knocked the loud- talker requires a fairly heavy current and for that e Down." In other words, the instruments come all ready reason thick wires must be used for connecting the trans- for you to assemble, all the parts, screws, nuts, washers, mitter with the loud- talker. If this is not done, the voice etc., being furnished. Complete directions how to assemble will be weakened considerably. If no heavy wire is at accompany each set. With a pair of band, more batteries must be used pliers and a screw -driver, the outfit to compensate. can be readily put together in less USES: This instrument can be used to than twenty minutes. transmit phonograph music from one room to another; used as a Detectiphone; as a Radio The most important point is that Amplifier; as a telephone extension (by plac- spool comes ing the regular telephone receiver against the the telephone receiver sensitive transmitter with the loud- talker); already wound complete, and the for salesmen to talk "through" window Experimenter will, therefore, not (Loud -Talker outside in street, microphone transmitter for salesmen, need to wind his own spool. talking into same) ; for restaurants for talking to the chef, and a hundred other uses. Many young experi- The outfit when assembled com- menters are developing a lucrative business prises a highly sensitive CARBON selling this appliance to various merchants GRAIN MICROPHONE with carbon at a good profit. diaphragm of exactly the same type Outside of the two instrument parts, one is with our $15.00 Detecti- three -foot cord Is furnished with sensitive as used microphone as shown; instructions, etc., are phone. (See our Cat. No. 19.) furnished. No. AEK204 "Electro" Loud -$1 The receiver is a special low re- Talker Outfit Parts "Knocked sistance double pole type with the Down," complete 50 difference that no magnet is used No. CEK205 "Electro" Loud - for the reason that the Talker Outfit, same as above in the same except that it is already as- A function of this instrument is elec- sembled and tested at factory $V< tro- magnetic, the same as all loud - Set complete .50 talking phones. Shipping weight 2 lbs. The spool is wound with special Immediate Shipments _ S. O. S.!! A REAL ELECTRIC Learner's Telegraph Outfit for 25c Prepaid In the 15 years of its ex- amm If the telegraph does not STRONG istence our company has ELECTRO Come up to expectation never offered such a bar- MAGNET F - == willwl cheerfully r e f u n d gain as the present one. money. Boys order 6 to 25 Just think of it, a real of these instruments. Sell t` - like hot cakes to friends electric learner's telegraph outfit with which to learn for 30 to 40 cte. each. So the code or to telegraph to small can be slipped into INICKEL BINDING POSTS WOOD BASE J pocket. LEARN THE your friend six blocks e. away, for 25 cts.!! Impos- -as. CODE DURING SPARE sible -you say. Quite so. TIME. TELEGRAPH OP- We do sell them at cost, ERATORS ARE SCARCE. but we do it solely to get you acquainted with us and UNCLE SAM NEEDS THOUSANDS. place our wonderful catalog in your hands. And if Important. As this telegraph is sold at cost, we this telegraph pleases,leases, you will orderd othero er ngs reserve the right to decline your order (by refund- from us. This telegraph has a red -lacquered wooden ing the money) unless you order one of our free base, strongg electromagnet, nickel binding posts, Cyclopedia Catalogs at the same time. Should you generous telegraph knob and nickel clicker. Tele- already have our Cat. No. 19, it is necessary to cut graph measures 31h x 114 x 1W over all. Full direc-d' out the coupon, writing across it: I have Cat. No. 19. tions for learning the code, and a fine CODE CHART This is done for the guidance of our catalog checking go with the telegraph, all packed in neat box. Tele- department. Of course, if you have Cat. No. 19, you graph works easily on a single dry cell. Two instru- need NOT send for it again. 50 if wanted, to We are prepared to fill orders for 10,000 of these tele- ments may be ordered for cts. graphs this month. They are In stock NOW. Your order telegraph between two rooms or two houses. 12 25c will be filled within hours. 25c maaa a a S ma S si S mi- - - A ELECTRO IMPORTING COMPANY "THE LIVEST CATALOG IN AMERICA" 231 Fulton St.. New York City Our big, new electrical cyclopedia No. 19 is waiting for you. Positively the most corn- I plete Wireless and electrical catalog In print today. 200 Big Pages. 600 illustrations, 500 I enclose herewith 6 cents for postage In stamps or coin instruments and apparatus. etc. Big "Treatise on Wireless Telegraphy." 20 FREE cou- for which please send me your latest Cyclopedia Catalog Tans for our 160 -page FREE Wireless Course in 20 lessons. FREE Cyclopedia No. 19 No. 19 as described. measures %5y'. Weight iS lb. Beautiful stiff covers. THE LIVEST CATALOG IN AMERICA" NAME Now before you turn this page write your name and address on coupon at left. cut or tear out. enclose 6 cts. stamps to cover mail charges, and the Cyclopedia is yours by return mail. ADDRESS THE ELECTRO IMPORTING CO., 231 Fulton Street, New York City STATE "Everything for the Experimenter"

E. E. 3-1311 You benefit by mentioning www.americanradiohistory.comthe "Electrical... Experimenter" when writing to advertisers. Electrical Experimenter 233 FULTON STREET, NEW YORK Publisht by Experimenter Publishing Company, Inc. (H. Gernsback, President; S. Gernsback, Treasurer;) 233 Fulton Street. New York Vol. VI Whole No. 64 AUGUST, 1918 No. 4

AERIAL MONO -FLYER OF THE FUTURE Front Cover EXPERIMENTAL PHYSICS. LESSON 14. Front a painting by George Wall By John J. Furia, A. B. M \ 2(3 A GIGANTIC EXPOSITION AND AMUSEMENT PARK IN JOHN BOTTOMLEY, DIRECTOR, MARCONI CO., DIES 244 THE MAKING By George Holmes 221 NEW GLASS SLATE FOR TEACHING RADIO HOOK -UPS ELECTRIC WHIRLING DISK TO START AND STOP AERO- 245 PLANES 223 ANALYSIS OF IRREGULAR WAVE -SHAPED ALTERNATING ELECTRIC SIRENS WARN PARIS OF AIR RAIDS 224 CURVES. HARMONICS- -PART II By Prof. F. E. Austin 247 OW THREE NEW YORK SUBWAYS MEET AND PASS ONE THE DESIGN AND USE OF THE WAVE- METER. PART IV. I ER 226 By Morton W. Sterns 248 SEARCHLIGHTS -THE NIGHT EYES OF THE ARMY. IIOW TO MAKE A SIMPLE SPECTROSCOPE. By Frank C. Perkins 227 By Donald S. Binnington 250 AERIAL MONO -FLYER OF THE FUTURE...By H. Winfield Secor 228 CLOCKWORKS WITHOUT GEARS. By Thomas Reeda251 RECLAIMING THE U. BOATS' TOLL BY NOVEL SALVAGE EXPERIMENTAL MECHANICS. LESSON V. THREAD CUT- OPERATIONS 230 TING By Samuel D. Cohen 252 THE MAGNETIC STORM By H. Gernsback 232 ON THE CONSTRUCTION OF SMALL TRANSFORMERS. ELECTRICITY AND THE RANGE- FINDER IN WAR 234 By Prof. F. E. Austin 254 WOMEN TO LEARN X -RAY WORK 235 EXPERIMENTAL CHEMISTRY- TWENTYSEVENTH LESSON - HOW BIRDS TAKE THEIR OWN PICTURES ELECTRICALLY. WATER By Albert W. Wilsdon 256 By Dr. E. Bade 236 HOW -TO- MAKE -IT PRIZE CONTEST 257 THE ELECTRICAL WOMEN OF ENGLAND..By Albert H. Bridge 237 WRINKLES, RECIPES AND FORMULAS...... By S. Gernsback 258 POPULAR ASTRONOMY -THE GASEOUS NEBULA- SECOND DIGEST 259 PAPER By Isabel M. Lewis 238 LATEST PATENTS THE PHENOMENA OF ELECTRICAL CONDUCTION IN GASES. WITH THE AMATEUR'S "LABORATORY CONTEST" 260 PART IV By Rogers D. Rusk, M. A. 240 PHONEY PATENTS 261 AN ELECTRIC CHICK PICKER 241 THE ORACLE 262

%A 191 t4' "'I " t i1 a 5 g>p:,gR cnw v JUL29 15 WAR INVEHTTIOo HS PA rENT [CD OMER'S Iliad tells us how the Greeks, tho Nor are they likely to do so. The Germans thought beleaguering Troy for over ten years, were the submarine would bring a decision, their experts unable to take the city, nor could they staking almost their last card upon it. It has proven force the Trojans to surrender. Finally, a ghastly failure, otherwise how could a million Amer- Úlf b.., so the legend goes, the Greeks constructed ican soldiers have landed in France, with hardly a loss a huge wooden horse, which in its interior worth speaking about? They tried Chlorin gas in a rant concealed many Greek warriors. This surprise action on the Canadians, putting several thou- horse was rolled triumphantly into Troy by the Trojans, sands of them out of the fighting, but as a whole it but during the night the Greek men escaped from the had no effect upon the war. horse and threw open the portals of the city. The Greek Suppose we send ten thousand bombing aeroplanes hosts having returned now swarmed into the city and over Germany. They alone will not win the war. Ten O sacked Troy. This was over two thousand years ago. thousand or fifty thousand tanks alone will not win the Legends such as these, it seems, were just as popular war. A thousand land battleships or a thousand other then as they are now ; at any rate the longing in the fearful land cruisers alone will not win the war. Raining human breast for the spectacular during wartime seems death and destruction upon the civil population as a hard to eradicate. rule has only one result : It inflames the people to It is only natural that war weary people should be fond greater deeds, to greater sacrifices, to greater hate, to (71 of giving their imagination free reign and of hoping thglsw greater determination to win the war. France, England by some miracle a wonderful invention will suddenly and Italy are shining examples of this. appear which will end the war with one stroke. No, any one invention is not likely to win the war. Unfortunately, history, with hardly any exceptions, Some day, perhaps, some one will invent an Atomic Ray o us i teaches that but few wars were won by means of which is capable of pulverizing whole regiments at a any one war invention. Wars in recent times from stroke. Nothing of this sort is impossible. But it is not t Napoleon down to this day were not won by means very probable. Rather it is the wholehearted devotion of any particular invention. Napoleon did not surrender of the non-combatants to a great and just cause that will on account of a war weapon that was known only to win the war. The nation that can throw into the scales O his conquerors. Nor were the American Civil \Var, the greatest amount of war implements, the heaviest the Franco -Prussian War, or the Russo-Japanese War weight of metal, the greatest amount of fighters, coupled won or lost by a new war machine. with a prodigious use of ALL of the best war inventions If this is true of all other great wars, how much will win in the end -PROVIDING THAT EVERY truer is it of the present cataclysm. Unheard and un- MAN AND WOMAN BEHIND THE LINES CON- dreamt of inventions, that would have staggered human- STANTLY THINKS AND DREAMS OF \VAR AND ity twenty years ago, have been thrown into this inferno, VICTORY AND IS PREPARED TO PUT EVERY and to what good? The bombing aeroplane, the sub- LAST OUNCE OF STRENGTH AS WELL AS ALL marine, wireless, trinitrotoluol, poison gas, the war WORLDLY BELONGINGS INTO THE RIGH- tank, liquid fire, the 75 mile gun, are all first class war TEOUS CAUSE WITHOUT STINT OR RE- inventions, every one of which would have spelled vic- STRAINT. tory to Napoleon, had he possest the secret. And THE GREATEST WAR INVENTION IS THE wonderful as every one of these inventions is, none of FIERY UNDYING WILL TO WIN. il-F them alone have been able to bring about a decision. H. GERNSBACK.

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EXPERIMENTER on Subscription 233 tiens cannot be returned unless full postage has been Included. ALL accented contribu- Fulton Street, New York. There E12 numbers spec priceIs tions are paid for on publication. A special rate Is paid for novel experiments; good year In U. S. and possessions. Canada and foreign countries, $2.00 a year. U. S. coin as Photographs accompanying them are highly desirable. well as U. 8. stamps accepted (no foreign coins or stamps). Single copies. 15 cents each. ELECTRICAL EXPERIMENTER. Monthly. Entered as second -elsss matter at the A sample copy will be sent gratis on request. Checks and money orders should be drawn New York Post Office under Act of Congress of March 3, 1879. Title registered U. 8. to order of EXPERIMENTER PUBLISHING CO., INC. If you change your address Patent Office. Copyright. 1918. by E. P. Co.. Inc., New York. The Contents of mis notify us promptly, in order that copies are not miscarried or lost. A green wrapper In. magazine are Copyrighted and must not be reproduced without giving full credit to the dental expiration. No copies sent after expiration. publication. All communisation, and contributions to this journal should be addrest to: Editor. The ELECTRICAL EXPERIMENTER Is for sale at all neumslands lo the United States ELECTRICAL EXPERIMENTER. 233 Fulton Street. New York. Unaccepted contrihu- and Canada; also at Brentano's, 37 Avenue de l'opera. Parts.

www.americanradiohistory.com219 220 ELECTRICAL EXPERIMENTER August, 1918 LEARN BY DOING' The Only Way to Learn Electricity

The only way you can become an expert is trical Contracting, together with the skill to by doing the very work under competent in- install, operate and maintain all systems for structors, which you will be called upon to do producing, transmitting and using electricity. later on. In other words, learn by doing. That A school for Old and Young. Individual in- is the method of the New York Electrical struction. School. No previous knowledge of electricity, me- Five minutes of actual practice properly chanics or mathematics is necessary to take directed is worth more to a man than years this electrical course. You can begin the and years of book study. Indeed, Actual Prac- course now and by steady application'prepare tice is the only training of value, and gradu- yourself in a short time. You will be taught ates of New York Electrical School have by practical electrical experts with actual ap- proved themselves to be the only men that are paratus, under actual conditions. s,000 of our fully qualified to satisfy EVERY demand of students are today successful electricians. the Electrical Profession. Come in and read their enthusiastic letters. Let us explain this course to you in person. If At this "Learn by Doing" School a man you can't call, send now for 64 -page book - acquires the art of Electrical Drafting; the it's FREE to you. best business method and experience in Elec- SCHOOL OPEN ALL SUMMER. Unusual Facilities for Providing Room and Board at Low Rates

NEW YORK ELECTRICAL SCHOOL, 29 W. 17th St., New York, N. Y. SNOOL Please send FREE and without obligation to me your L4- page book. ECTR CA Name 2s w. ITTn ST Street NEW YORK EL NEW YORK, N. Y. City

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www.americanradiohistory.com Vol. VI. Whole No. 64 AUGUST, 1918 Number 4 A Gigantic Exposition and Amusement Park in the Making The New York International Exposition Which Is to Mark the 300th Anniversary of the Settlement of The Bronx By GEORGE HOLMES

OURS is indeed an age of wondrous With the gigantic Merchant Marine now industrial expositions ever seen east of the achievement. Altho we are in the in the making it will eclipse all others and Dfississippi. midst of the world's greatest war, our flag will flutter in the breeze of every It is to be a permanent enterprise on the it is not to be said that we are seaport in the world. general style of Shepherd's Bush and Earl's the least bit doubtful or discon- But to obtain all this foreign trade we Court in London. It is destined to be a certed with regard to the ultimate finish. must needs have some way of inducing the clearing house of industrial ideas, efforts

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Copyright, 1915, by N. P. CO. Night Scene at the New New York International Exposition, Where Science, the Arts and industry Will Hold Your Attention Every Year from May to November. The Beautifully illuminated Swimming Pool Here Shown Is the Largest in the World. It Has a Glass Bottom Thru Which Vail- colored Lights Glow While the Sixty -five Foot Water -falls Is a Dazzling, Shimmering Mound of Ever -changing Colors. Electric Pumps Constantly Change the Water in the Pool so as to Keep It Fresh and Pure, the Sea Water Being Past Thru Chlorid Purifying Tanks and Then Liberated over the "Falls," Which Aerate and Revitalize It.

Therefore, while we are doing all we can buyers to see our goods and products in and inventions and real accomplishments. to destroy autocracy and promote world- such a way that they will be imprest. With A central market place where the manu- wide democracy and freedom our "after - this ultimate point in view there is today facturers of America can show to the the -war" army is already busy preparing for being erected and soon to be thrown open buyers of foreign lands the triumph of the great industrial struggle that is to come. to the general public, one of the largest American industrial genius. 221 www.americanradiohistory.com 222 ELECTRICAL EXPERIMENTER August, 1918

It is to be a vast educational institution on to 500 carpenters, electricians, painters, constant motion by special gears and huge for the instruction of the people along sci- plasterers, laborers, supervisors and other electric motors, producing rolling foaming entific, hygienic and artistic lines. officials engaged in making New York's breakers that bid fair to rival any that And, withal, a huge recreation center and new Exposition a real, live-wire affair. his majesty, Father Neptune, ever splashed playground where 250,000 persons can be The grounds cover a total of 28/ acres Coney's bathers with. The pool proper will accommodated each day. fronting on the Bronx River at 177th Street, contain something like 2,500,000 gallons of The Exposition will be held each year a tract of land belonging to William Wal- water and gradually slopes down from the depth, at which point from May 30 to November 1. The ex- dorf Astor. To start with the site re- level to a four -foot will be placed the "life lines "; beyond this point the drop is fairly rapid until a ten - foot depth is reached, where there will be the usual dare -devil platforms, chutes and other swimmers' paraphernalia. Beneath this deep section on the floor of the pool there is set a series of spaces covered by a heavy glass frame, underneath which will be various colored electric light combinations. These lamps are controlled from shore and when lit up at night present a very beautiful spectacle, not to mention the series of flood and searchlights which will play on the scene. Perhaps the greatest spectacle of all will be the gigantic illuminated waterfall at the deep end of the pool. At this end there will be a very pretty back -ground of mountains, hills, Alpine houses, mountain streams, etc., and over these will trickle the water and spray, while in the center of this imposing array will be the sheer drop, Daylight View of "Bronx Exposition " -Gigantic Sea Water Swimming Pool Can Be Seen at Left of Photo, and 65 Foot Electrified Water -Falls at Extreme Left. like a plate of glass from the top of the mountain to the water sixty -five feet below of a dazzling waterfall, which, while a hibits this year will number about 250, rep- sembled a large swamp ; by gradual cutting wonderful novelty in itself, will also im- resenting eight countries and will be housed and filling some semblance of order was prove the purity of the water in the pool. in twenty-five magnificent buildings. There finally secured, but not until many feet of Then there will be a very pretty grotto in will also be Government exhibits from five solid rock had been blasted away to make back of this waterfall, where one may ob- departments and it is planned to add more room for the numerous gas, water, sewer serve the seething foam below and the each succeeding year. and electric pipes and conduits. For the great array of lights. This vast enterprise is backed and under water supply to the various buildings and Besides having the waterfall to purify the guidance of some of the most promi- fire hydrants, over a mile and a half of the water, provision is made so that it can nent men of the commercial world in the main pipes have been laid down, not to be kept going continuously, thereby adding United States. They believe that the mention eleven miles of small water pipes new and clean water all the time and drain- struggle for commercial supremacy will that branch out from the main supply pipe ing away the old water in proportion. naturally center in New York, hence this somewhat like the branches of a giant tree. Water is pumped about a mile to the location for the Exposition. There will also be a very large number of grounds from a point where there is an electrical The plans for the New York Interna- conduits and as our friend, the 11 -foot tide, this being right near Long tional Exposition are the most stupendous publicity manager, said with a mournful Island Sound. The intake pipe is five feet yet conceived from bcginning to cnd. Of note -"threc hundred thousand dollars have below low tide; by having it so arranged it been buried in these grounds where the is possible to avoid sucking in all the drift the twenty-five buildings some will be de- public 'will never voted to the display of scientific, artistic see them." scum and other foreign matter which ac- Biggest and best of all will be the amuse- cumulates on the surface. In addition to and industrial triumphs of the world, others ment to of the better class. features that will be the delight of this there are placed over the opening entertainments the kiddies and make the grown -ups feel The buildings be known as several metal screens of a very fine mesh. exhibit will like little tots again. First will be the Passing thru the pipe line the water will the Palace of American Achievements, greatest inland pool ever made with real Pan- Exhibits, Palace be pumped by the aid of large electric Palace of American salt water from the Atlantic Ocean! It pumps into a large reservoir capable of con- of Fine Arts, Palace of Manufactures and will be three hundred by three hundred Industries, taining several hundred thousand gallons of Liberal Arts, Palace of Varied and fifty feet and will have a sand beach water. This reservoir is "V" shaped and Horticultural and Agricultural Hall, Ma- three hundred feet long by fifty feet wide, and In situated at the back of the pool and the chinery Hall Automobile Salon. wherein one may acquire a beautiful coat waterfall. Here the water is allowed each of these will be displayed exhibits in to keeping with the name of the building. That these displays will be most interesting is evidenced by the fact that already the United States Government has announced its intention of participating with an exhibit by the Bureau of Mines of the Department of the Interior, and by exhibits from the Army and Navy Depart- ments. There also will be a department devoted to food conservation, dehydration and scientific cookery, which will be under the direction of Mrs. A. Louise Andrea, one of the best known cooking experts of the United States, who conducted a similar department at the San Francisco Exposi- tion in 1915. The entire Exposition, however, is not of the serious nature to be found in the Exhibit buildings. The management knows Before the "Bronx Exposition" Swimming Pool Was Filled With Millions of Gallons of that the people must be entertained as well Sea Water. 1 -Bath House; 2 -Motor Driven "Wave Producers "; 3- Framework for 65 as instructed, and to this end there are be- Foot Artificial Water -Falls and Rocks. ing erected a number of entertainment features that bid fair to rival anything ever of tan or make sand houses or some equally settle and then it is again pumped thru attempted before, either at an Exposition non - called - for feat which nevertheless six large lime chlorid filters and then thru or Amusement Park. serves to amuse. In addition to the beach the pipe line to the top of the "falls," With the opening date but a short dis- there will be a gigantic wave motion ma- where it is sent hurtling over the top into tance away the grounds represent a veri- chine operating mechanically by means of the foment below. All in all the pumping table bee -hive of activity, there being close big plungers. These plungers are kept in (Continued on page 267)

www.americanradiohistory.com August, 1918 ELECTRICAL EXPERIMENTER 223 Electric Whirling Disk to Start and Stop Aeroplanes

NOW that we have instituted a daily be picked up by machines starting to Wash- might be employed; the first working on the aerial mail service between New ington or Boston. He further stated that principle that the rotating disk be driven in York and Washington and also representatives from several aeroplane con- an opposite direction to that of the aero- between New York and Phila- cerns had measured the roof of the New plane, which will in this case tend to quick- dephia as well as Boston, the mat- York Post Office and reported that in their ly decelerate and come to a stop. The sec- ter of making sure that the mail -planes start estimation it was entirely feasible and prac- ond arrangement would be to use large off on their journey on time is a critical ticable for the mail- planes to start and electro -magnets as shown herewith, and in problem and moreover, the Post Office au- alight on the roof thereof. They proposed this case the revolving disk could be driven thorities at New York have bethought them- to build an aeroplane accelerating and de- in the same direction as that followed by selves that it is really going around the bush celerating machine for starting and stop- the alighting 'plane, and by applying the cur- to send the aerial mail sacks via train to a ping the aeroplanes in such a space, at a rent to the magnets gradually, and thus in- flying ground, located fifteen miles from the cost of something like $50,000. creasing their strength, the speed of the Post Office in the center of the city. It has The proposed scheme is illustrated here- alighting 'plane and its attached iron arma-

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MO/. I'o ROTATE. AEROPLANE ACCELERATOR.

Copyright, 1918, by E.P. Co. The Aerial Mall Has Arrived at Last. Every Day the Mail- planes Soar Thru the Air from New York to Washington, and Vice Versa, as Well as Between Boston and New York. At New York, Owing to the Many High Buildings, the 'Planes Cannot Leave the City Post -Office at Present. It Has Been Proposed to Erect a Gigantic Merry -go -round Accelerator Device, Such as Here Pictured, for the Purpose of Speeding Up the 'Planes at Starting and to Decelerate Them as They Land from the sky.

recently been suggested in the daily press by with, and as can be seen, it possesses many tore would be reduced by co- action with various writers that some scheme should be novel points. It resembles in general a the electro- magnets in such a way as to available whereby the mail- planes can fly carousel or merry-go- round, by which means simulate mechanical friction of gradually directly over the city and alight on the the aeroplanes are supposed to be spun increasing magnitude. Post Office building itself, and in this way around in starting until their propellers have It thus becomes evident that those in save several hours daily in delivering the attained sufficient speed and then be sudden - charge of the plant, and stationed in an aerial post, as well as gaining a consider- ly released, when they will be thrown off observation tower on the roof, may readily able amount of time in starting on their the disk tangentially by centrifugal force exert perfect control over the accelerator, journey. by means of a quick- acting release clutch or both as regards the speed of the electric It was stated by Superintendent of Mails, better still, by the utilization of powerful driving motor, the direction in which the E. M. Norris, in regard to these sugges- electro- magnets arranged around the elec- disk is rotated, the strength of the electro- tions, that it was entirely feasible for aero- tric motor -driven disk as proposed by Mr. magnets, the moment of breaking their plane mail to be dropt on the roof of the H. Gernsback in the June issue of the circuit, etc. A storage platform for extra New York Post Office, and provided floe ELECTRICAL EXPERIMENTER. or disabled 'planes is arranged at one side of high buildings of the metropolis would per- This remarkable apparatus is also sup- the accelerating machine, and this can be mit the aeroplanes to fly sufficiently low, that posed to prove efficacious in decelerating or supplied with electro- magnets for holding the mail could be easily dropt as sug- gradually stopping aeroplanes as they alight the 'planes securely as shown in the illus- gested, on the roof of the Post Office under from the air. tration. It is possible that the device may most conditions, but that it could not In this case there are two schemes which be soon tried out.

www.americanradiohistory.com 224 ELECTRICAL EXPERIMENTER August, 1918

Electric Sirens Warn Paris of_ Air Raids

S are not just yet accus- bother it here. The French do not use waves set up in the air by the siren must tomedtoured to aerial raid warnings, but stoves the way we do; they are acclimated have a clear way thru the air in all direc- those who live in cities near the to the chilling air which often blows over tions to carry any appreciable distance; Atlantic Coast are shortly to be in- this part of Europe and it greatly amuses they must not be impeded by any ob- itiated in all the arts and graces a Frenchman to see a Yankee shivering struction or else they will be greatly weak- of "crawling into a rat hole," when the like a leaf, and calling loudly for "heat i' ened, or even dissipated in a very short distance. These powerful sirens are practically all electrically operated and controlled and involve many unique features. Some of them operate on a blast of comprest air, which is caused to blow a large whistle or vibratory diafram whenever a magnet- ically controlled valve is opened. Others are designed upon the principle of the true siren as found in the physics laboratory, and based upon the fact that if we rapidly rotate a perforated disc in front of a stream of air, such as from a nozzle, then a shrill, whistling sound will be produced and the higher the speed of the disc the higher the pitch of the sound. The blast of air to be thus chopt up by a perforated disc or drum need not be supplied from a source of comprest air but may be that due to the high velocity of a revolving perforated drum, as is the case with the siren illustrated in Figs. 1 and 4. In this design of sound producer there are two similar drums or rings, each perforated with an equal number of periferal openings as shown. The outer drum is stationary, while the inner drum is rapidly revolved by an electric or other motor. The inner revolving drum is designed to give a fan effect and sucks in the air, in this way creating a strong air blast thru the Fig. 1. This Gigantic Electric Siren, Installed on the Tower of Notre Dame, is but One of the Twenty -six Fixt "Aerial Alarm" Sirens Installed All Over Paris to Warn the People. openings in the two drums as they are rapidly opened and closed. The faster the higher the pitch of the giant alarm sirens sound. In Paris and The chimney is a long beloved mark of drum rotates, the London the people are thoroly trained distinction and artistic display on Parisian note produced. Some of the large sirens in the procedure to run for cover when an houses and some large At require a motor of several horse-power, the are quite affairs. 10 to 15 aerial raid alarm sounds. Suitable under- last the war has found a practical use for revolving siren blade measuring ground caves and caverns are provided and them, for the chimneys, projecting up above feet in diameter. properly labeled, so that the inhabitants the roofs as they do, provide the necessary The powerful Blériot (French) electric can quickly find cover. In Paris there elevations on which to mount the siren siren of the vertical motor -operated type are now several underground theatres, as alarm equipment. The acoustic sound illustrated at Fig. 3, is interesting. Here well as a host of subterranean restaurants and cafes. Even blasé "little old New York" has awakened to the imminent danger of being attacked by U -boat hydro- planes at night, and the military and police authorities have had a number of powerful electric sirens installed, as well as numerous anti -aircraft guns. The gigantic electric siren shown in Fig. 1, is placed on the tower of Notre Dame in Paris and is one of the 26 fixt sirens that are being installed all over Paris to warn the people of air raids or the approach of the shells from the long range 76 -mile German gun. The sound from each of these sirens will carry a distance of 1,500 meters, or for nearly one mile. One of these sirens will be placed on each of the other prominent Paris monuments. The operating motor is observed near the electrician's hand. It requires quite a powerful electric motor to whirl the siren blades of these extra large warning signals. The illustration, Fig. 2, shows another installation of an "air raid" warning siren on a Parisian house -top. Note the three electric feed wires running over to the motor, which is located in the base of the siren. This particular siren is installed on the top of a chimney, as are many others in Paris, but this would hardly prove pleasant for the machinery, in America, as the Yankees make use of all their chimneys more or less regularly. In Paris, however, Photo by 'Underwood 8 Underwood the chimney -top is a safe location for any Fig. 4. First Electric Siren Installed In New York City In the Theater District for such device, for smoke and heat will not Warning Against Aerial Attacks. Many of These Will Be Used Thruout the City.

www.americanradiohistory.com August, 1918 ELECTRICAL EXPERIMENTER 225 the base 1 contains the electric motor which ture me, I realize it. A china nest-egg's drives a vertical spindle or shaft, to which demoralizing enough, but at least it's full are attached the necessary fan and siren ele- of air, and the hen is encouraged to put ments within the casings 5 and 6. The air something inside her product. But an ac- is drawn in thru opening 10. The siren tual vacuum-no; if she ever got wise that sound waves emerge from openings 6, at people paid money for that sort of contents the top. An electric "commande" or con- -good night! troller is fitted at the top of this siren, in But, because I'm floored is no sign that the cap 7. To this magnetic controller some other Bug won't come across with a there is connected a circuit linked up with wonderful use for defunct Mazdas -some- a source of power and a Morse key 9. It thing that will lift the mortgage from the is thus possible to actually telegraph with home, maybe, or provide Big Sister with a this siren, its shrill -piercing note having beau. Give him time. been heard at a distance of 2,500 meters or Meanwhile, let's give due credit to our about 154 miles when the actuating motor hard -working Ed. Give it to him now, and siren drums revolved at 5,000 revolu- while it's worth something -not wait till tions per minute. he's so obvious that the Sunday supple- The internal arrangement of this electric ments are writing him up. If you wait till telegraph siren is very ingenious. To shut then before you say "Him? Oh, yes, I off the sound rapidly, as in telegraphing, useter know him," you're liable to get back the inventor provides a third or intermedi- a sarcastic "Yes, you did! You knew all ate perforated drum having openings equal the celebrities, didn't you, from Steve in number and size to the usual fixt and Brodie to the Ahkond of Swat!" Wouldn't revolving members. This intermediate that be tough, when you really did know drum can be moved back and forth around him after all? its axis by means of the electromagnetic I'll say right now that I'm looking for controller 7. so as to more or less line up some Bug to develop an idea from "E. E." its openings with those in the fixt and ro- into one of the big inventions of the world. tary drums; the nearer the openings in the It might surprise the Ed., tho it wouldn't three drums align, the greater the volume me, if some day one of those conscientious of sound liberated from the apparatus. The insects should stroll into 233 Fulton Street with a bag full of bills, and remark, "Doc, driving motor 1 revolves at constant speed. Where the signals are to be broken up at the wi fe says your paper was what started relatively long periods, say every five min- my invention, and here's a million dollars utes, then it is only necessary to utilize a she held out of the last pay- envelope for plain type of motor -driven siren, when by you, with our compliments ! "* opening and closing the motor switch the Success to "E. E." and the next 100,000 soon! desired intermittent signals will be given. F g. 3. A French Electric Siren of the Thanks, awfully, Tom1 Figs. 4 and 5 show an American type of Du- B erlot Vertical Type. It Is Operated By a I compromise with the Motor In the Base and is Provided With a "insect" on 50% i.e., $490,000, (the $10,000 deduc- plex siren, driven by a two -horse electric Magnetic Controller at the Top, which Per- tion represents a cash discount of 2%) if he or it motor. At one of the southern flying fields mits of Rapidly Opening and Closing Its shows up at once!! And if the "insect" insists that in Texas, there is in use a powerful electric Raucous Throat, So That Telegraphic Sig- I take the other 50% -well, I'll not be harsh. I'll nals Can Be Transmitted When Desired. get out a fine supplement for the next issue, pre- siren that gives out the "fog" and other senting each reader with a $5.00 W. S. S.II For warnings to aviators, which can be heard you see, it's the readers who by their support make possible the "E. E. "1 -"Eo." five miles away. in a cloud of dust. in the wake of the Saturday Evening Post t I'll say that's "GARABED " A FAILURE, SAY ACCOUNTING FOR THOSE 100,000 going some! GOVERNMENT EXPERTS. READERS. We've got to account for it in some way, "Garabed," which was to revolutionize the By THOMAS REED same as any other weird phenomenon- world by the production of an unlimited IT was a big surprise, eh, Bugs, to learn make up our minds what it was punched free energy, is a failure. This was the re- that our Magazine had grown to 100,000 Maggié s accelerator so. And my guess is port of the board of five scientists ap- circulation? What do you think of our that it's our Editor's propensity for "start- pointed by congressional resolution, made Little Maggie hot -footing it down the road ing something." public by the Interior department July 1. I'll bet that fellow starts things The report says the principles of the in- in his sleep. He isn't satisfied with vention of Garabed T. K. Giragossian are digging up for us the newest ap- unsound. paratus and processes, and researches and theories, but he must have our laboratory- pictures, and "dope" how to make things with nothing to make 'em of, and burned -out lamp competitions-all sorts of stimulants to keep us awake and thinking. If one of his suggestions seems to go dead, no matter, he leaves it and starts something else. But do they ever go dead? I don't believe so. Now and then one of 'em may appear to bury itself in the soil of Bugdom, like the "dud" shells they talk about, and be lost ; but somewhere or other, I'll warrant there's an obscure but diligent Bug sitting on the lost idea, prying away at its nose -cap with a screw -driver, bent on making something out of it, and in a fair way to succeed if he lasts long enough. Different minds are open to different ideas, you see. For instance, mine's absolutely closed to this utilization of burned -out lamps. I might as well be a wooden man, for all the chance I stand in the contest. I rack my weary bean, and nothing comes out but an opaque Fool Idea, that stands in Photo ® by Underwood & Underwood the door and blocks the passage for anything sensible. Flg. 5. Another View of the New York Electric Fig. 2. Paris Has Many of These Electric Siren Shown In Fig. 4. It is Fitted With a Two What do you suppose it is ?-a nest- Sirens Installed on Chimney Tops and Other Horsepower Motor and Can Be Heard for Two Miles. egg! It's dead wrong-don't lec- Elevated Points to Warn of Aerial Attacks.

www.americanradiohistory.com 226 ELECTRICAL EXPERIMENTER August, 1918 How Three New York Subways Meet and Pass One Another

THOSE of us who do not use the meet at the corner of Broadway and 42nd the bird's -eye view clearly indicates, it pro- great subway systems of the larger Street, better known as "Times Square," ceeds to dip under the old subway line at cities such as New York are often and it is at this point, extending over an 42nd Street, but has no track connection prone to forget entirely some of the area from 42nd Street to 46th Street along with any other subway. The new B. R T. really wonderful engineering work 7th Avenue and also Broadway, that the Broadway line then extends northward to carried out in the bowels of Mother Earth. new Brooklyn Rapid- Transit subway has the south end of Central Park, or 59th The subway construction engineers of New been constructed, so as to run under the Street, and from this point it runs directly York City, and including Brooklyn in this present subway, which proceeds along 42nd east across the East River to Long Island consideration, have solved in recent years Street, and all this work was done without City. some of the most difficult subway construc- interfering with normal traffic. The entire The new 7th Avenue subway on Manhat- tion problems imaginable. This is so for re- arrangement of the "Times Square" sub- tan Island will extend from the Battery a number of reasons, among which are the way station and the interconnecting pas- uptown on 7th Avenue and will branch into present subway plans of this first city of sageways joining the new B. R. T. subway the existing subway system just above 42nd America, calling for a great number of in- (running along Broadway) with the old Street and Broadway as the illustration de- tersections and cross -overs on the different subway, which is to be operated simply as lineates. Express service will be main- lines, many of which take place under a "shuttle" between "Times Square" and the tained on this route thru the new station at

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NEW BROOKLYN. RAPID TRANSIT ' ' // .i' SUBWAY ON BROADWAY Copyright, 1915. by ]t. P. Co. New York City Has Undoubtedly Solved Some of the Most Complex Subway Problems In the World. Here's a Typical Case: -At the Corner of 42nd Street and Broadway Three Subways, All Heavy Arteries of Traffic, Meet and Pass on Their Way. The Old Subway Transports its Passengers by "Shuttle" train from "Grand Central" to "Times Square ". Here They Can Descend to the New B. R. T. Subway, Which Dives Under the Present Interboro Tracks as Shown, or They Can Take a "Seventh Avenue" Express Uptown or Down- town. Counting the Trolley Service, Three Track Levels Are in Use at Thls Veritable "Hub" of New York's Traffic. ground. Moreover, some of these under- "Grand Central" terminal, will be made "Times Square," and on uptown over the ground tubes must be built under existing more apparent by inspecting the street plan old subway tracks. subways, without in any way interfering of these subway changes given herewith. If you should happen to be downtown with the normal daily traffic. New York The previous or existing subway system near the Brooklyn Bridge, and wisht to use City has one of the most extensive subway* runs in the lower part of New York along the old subway system, you would take an systems in the world, comprising as it does Fourth Avenue to the "Grand Central' express to "Grand Central" terminal; from more than two hundred miles of under- terminal which is the terminus of the New that point you would take the "shuttle" ground railway. Some of these subway York Central Railway, the N. Y., N. H., train across 42nd Street to the "Times routes which honeycomb the soil of the and Hartford R. R., and other systems, Square" station from which point you have great metropolis have necessitated the bor- from which point it proceeds westward the choice of several directions. You can ing of tubes under the East river, at enor- along 42nd Street, to the "Times Square" go uptown either on the old subway system mous cost, and under difficulties which station situated at Broadway and 42nd via a 7th Avenue express, or you could by would seem to require almost superhuman Street, and from this point it runs along the same means proceed downtown. If you endeavor. Broadway uptown to 96th Street, etc. so desired, you might pass thru the under- The present illustration shows in a vivid The new B. R. T. subway crosses under the ground passageway downstairs to the B. R. manner one of the greatest subway en- East River from Brooklyn and enters New T. subway, running below you via Broad- gineering feats ever performed. Three York City proper near the Battery, from way, and by passing thru a turn -stile and great arteries of underground traffic now which point it runs up Broadway, and as (Continued on page 284)

www.americanradiohistory.com August, 1918 ELECTRICAL EXPERIMENTER 227 Searchlights -The fight Eyes of the Army By FRANK C. PERKINS

THE accompanying photograph shows a is effective up to a mile on a good clear U. S. Army electric searchlight, fitted with recent design of American portable auto night. a collapsible steel mast of considerable searchlight for military field use as It is declared that in order to get the height. These searchlights are intended demonstrated at the Marine Barracks, maximum value of the lamp, the observer for special work and can be removed from League Island Navy Yard, Phila- delphia Pa. It was also tested out before the Engineering De- partment at the Washington Bar- racks, and the Maryland State Mili' is made very interesting experi..ients with it in their maneuvers. It is stated that after the first test was made at League Island, a very thoro report was made by the officer in charge, which showed that on a dark night with sleet falling, each lamp gave good illumination at distances up to 1,500 yards. The military officials have taken particular interest in this auto searchlight because of the conditions in the European war and during the operations of the American Marine Corps at Vera Cruz and Culebra showed the need and the varied uses for Photo ® by Central News Photo Service such an equipment. Above:-Battery of Powerful Electric Searchlights to Be Used by Uncle Sam's Boys in Fighting Back the German It is pointed out that the fea- Hordes. tures to be incorporated in any At Left: -Close -up View of One of the U. S. Army Search- such portable light must include lights Mounted on a "Climbing Mast." It Can Be Rapidly reliability, ruggedness, ease of Elevated to a Considerable Height. carriage and construction of such nature that all of the set may be stands at some distance to one side, and the truck when desired. They are fitted quickly assembled and placed in operation. by means of a field telephone the officers with reels of flexible cables as will be seen, The electrical apparatus of the equipment control the operation of the light as found these reels maintaining continuous contact is mounted on a special body on an autocar necessary. Some of these field searchlights with the feed wires from the dynamo at all chassis. The body is designed so as to fur- are fitted with remote ¿control attachments times, by means of a brush and ring ar- nish protection for the power plant, and to so that the beam can be focust on the rangement. support the four reels of flexible cable, and target or object by simply pressing a series Electric searchlights are invaluable as a the spring mounted tracks on which the two of buttons a quarter of a mile away. protection against enemy air raids upon searchlight hand trucks rest. These springs The Italian army held a mountain pass, at towns or cities. Since many coast cities are are quite essential in eliminating road the base of which ran a turbulent stream. now in darkness at this time, these pictures shocks from the delicate mechanism of the The Austrians were in force on the oppo- are of added interest. lamps. site cliff. This is what the sons of Gari- One of the photos shows a climbing mast It is of interest to note that the power baldi did: they prepared a powerful battery fully elevated. This elevating attachment plant consists of a gasoline motor with 43g" of electric searchlights. near the top of the is used in case the lights are hidden behind x 434" cylinders, coupled direct to a 7- mountain, well camouflaged. At night they trees, walls or bushes for the purpose of kilowatt direct-current generator. This flashed a perfect blast of blinding white concealing them from the enemy observers. generator is designed to run at 1200 revo- light down on the Austrian lines, while in This photo was made at the Mobile Anti - lutions per minute, at which speed it gives the cover of abrupt darkness below their Aircraft Section of the Engineering Corps, 125 volts and delivers 56 amperes. The searchlight beams, the brave Italian en- Washington Barracks, Washington, D. C. motor is equipt with a fly -gall governor, gineers worked like demons and swung The third photo illustrates a battery of regulating the speed within very close limits. rope bridges across the stream, which was searchlights in operation at night locating The motor driving this generator is sup- of considerable width. aeroplanes that are sent up for the purpose plied with its own gasoline tank, and also One of the photos herewith shows a new of detect;n; enemy aircraft. an independent radiator kept cool by a high- speed fan. It may be stated that the two hand trucks which carry the searchlights and reels of flexible wire are constructed entirely of steel and aluminum, and have each two wire wheels equipt with 28" x 3" pneumatic tires. These trucks are light in weight and rigid in construction, and so designed that they have large road clearance beneath the light to enable them to be operated in very rough country. For supplying the necessary current each light carries 1350 feet of cable, divided into two lengths of 675 feet each, so that each lamp can be operated independently of the other at a distance of one -quarter mile from the generating plant. By means of specially designed attachment plugs and reel arrangement, the light can be operated at any distance within the limits of the cable from the power plant without unreeling all of the wire to get at the inner end. The inner ends are arranged to pass thru the heads of the drums, so that the attachment may be readily made. Each searchlight measures 14 inches in diameter and has an For Rapid Maneuvering of Troops at Night the U. S. Forces Will Have Available a Large arc of five thousand candle -power, and Supply of These Auto -truck Searchlights.

www.americanradiohistory.com 228 ELECTRICAL EXPERIMENTER August, 1918 Aerial Mono -Flyer of the Future By H. WINFIELD SECOR

THE high -speed electric train of the indicates that the gyroscope is failing, due direct or alternating current can be utilized. future will undoubtedly be radically to lack of current, etc., he immediately A third way of supplying electric current different in design from the railroad pushes the emergency button which re- to the mono -flyer is by the one -wire, high cars of the present day. For many leases a set of magnetic locks; these locks tension, high frequency system of Tesla. locations, especially in mountainous set the inner compartment free and as the In his works on high frequency currents Dr. regions the electrically operated mono -rail whole car of the mono -flyer slowly turns Tesla shows and describes a one -wire motor car, illustrated on our front cover as well over about the cable, as already explained, which he built and demonstrated success- as on this page, will prove of particular the passengers are kept on an "even keel" fully. This method of distributing electric value. To begin with this aerial mono - as it were. energy is ideally applicable to the present flyer is enabled to run along at speeds of The method of propelling the car, either railway. The steel cable upon which the 200 miles per hour or faster on a single along cableways over mountain passes as car travels could be charged by a sigh rail or cable, thanks to the wonderful stabil- frequency, izing qualities of the gyroscope, a small loud -speaking Signo/ lights unipolar cur- sized one being easily capable of maintain- radio receiver i rent and the ing a 100-foot car in an upright position on motors oper- a mono -rail or cable. Among other inter- ated on the esting technical features of this thoroly Tesla one- practical passenger carrier are the aero- wire method. plane propeller drive, unique method of Electric Also, to in- supplying electric current to the car motors, head /tghf tensify the safety- attachments to prevent the car from corona trans- dropping mission a light Electric cob/es b l e should the to controller feeder ca gyroscope Rodio ontenno could be run fail, and a along just number of 'rope /ter above the car, other interest- motors "y . the two cables ing depar- Radio antenna being oppo- tures, based ;.Rollers sitely charged on s o u n d with a high engineer- tension, high ing principles Gyroscope frequency which our and motor current. The technical ex- lYthtOMs corona leak - perts are quite `Sp'L 2 contort trolley a g e between familiar with, Aoxihóry Rovoble passenger compor/menf such highly but which storage Gut/erg 'alee/loop and wheel charged con- have not as Air propellers ductors is yet found Electro magnetic Magnetic enormous, and practical ap- brohes /oars- not easily application. preciated b y and - steel cable with The mono- Special ± Movable inner%' cc anyone w h o rail flyer is insulation between /be strands passenger comportment has never seen not as imprac- Gyroscope such a dis- tical as would Conmound +and- sleet charge. This at first ap- cable corona is like pear for such Semi- sectional Side View and Center of the "Aerial Mono -flyer of the Future," Which Can Run Along a a silent effluve a single - rail Single Steel Cable Stretching Across Deep Ravines and Canyons. It Is Propelled by Powerful Alr Pro- and will ' fill car carrying a pellers Driven by Electric Motors. The Motors, Lights and Signals Are Furnished with Current thru the air space a Special Duplex Cable a Double- contact Trolley Wheel. p a s s e n- and between t w o ger had been opposite- operated by Brennan, the English en- here shown, or over regular mono -rail land ly charged conductors separated 6 to 8 feet gineer, several years ago. His car, systems, is by high speed air propellers. apart, when charged by such potentials as fitted with a small stabilizing gyro- This idea may not seem feasible at first 150,000 volts.. A number of the long dis- scope, travelled along upright on a single but the practicability of the scheme is at- tance transmission lines of today utilize rail very successfully. If you wish to dem- tested by the gigantic Caproni triplanes, as voltages of this order, and the reader may onstrate this remarkable power of the gyro- well as large English bombing planes, some gasp when he thinks of what might hap- scope go to the nearest toy -shop and pur- of which have as many as four propellers pen if our mono -flyer was rolling along chase a 25 cent gyro. You will find that if and a carrying capacity of fifteen to twenty peacefully between two cables charged at you stretch a piece of string horizontally passengers. The mono -flyer propellers are 200,000 volts and a short- circuit should or at an angle that the upright gyro, spin- driven by electric motors controlled by the occur. Well he might hold his breath if ning at high speed, of course, will travel motorman at the front of the car. the current were of 60 cycles frequency, along the string upright. Another impor- The next proposition is how to supply for then there would be some fireworks. tant fact is that as the gyro's speed de- the car with current. There are three meth- Sixty cycle current kills. But this same creases it cants over gradually more and ods by which the car can be electrically 200,000 volt alternating current if oscillat- more, which action you can readily demon- operated. The first is to employ a gasoline - ing at half -a- million cycles per second strate for yourself ; moreover, this shows electric power plant; in this unit a petrol would: be harmless. Besides, the passengers that if the mono -flyer's gyroscope should fail motor drives a dynamo and the current de- in the steel car would be protected from at any time then the car would cant over livered by it is supplied to the propeller and any shock as the currents, in the event of easily, not rapidly, owing to the great mo- gyroscope motors thru regulating rheostats a short -circuit, would pass thru the steel mentum of the gyro wheel. Thus it is in the usual manner. The second scheme frame. the decelerating gyro and car slowly reach is the one illustrated herewith in which Two views of a Sperry ship -stabilizing a neutral or hanging position, which it will the positive and negative currents are gyroscope of the electric motor -driven type safely assume when provided with guard carried by a special duplex cable, so wound are illustrated herewith as of interest to rings and cable wheels as our illustrations as to provide alternate -1- and contact show. An ingenious arrangement of the surfaces - readers of this article. The sectional view continuously along its surface. A shows the driving motor mounted inside inner passenger compartment of the mono - specially contrived + and - contact trolley flyer has been worked out for such emer- wheel rolls on this double polarity cable, the casing of the 24 -inch diameter gyro gency conditions, and this involves the free gathering the positive and negative electric rotor. The motor is an A. C. squirrel suspension of this compartment on roller currents respectively. Owing to the pecu- cage induction motor. ' The gyro is fitted bearings as indicated in the end -wise sec- liar construction of this contact wheel, with with a motor -operated vacuum pump which tional view of the car. The inner cab is not its spiral shoes and the spiral arrangement keeps the gyro chamber exhausted of air, free to rotate on its axis normally, but as of the opposite conductors in the cable, the in this way eliminating considerable losses soon as the gage in front of the motorman circuit is completed effectively. Either due to the windage of the massive high

www.americanradiohistory.com August, 1918 ELECTRICAL EXPERIMENTER 229

Sectional View Thru Modern Electric Gyroscopic Stabilizer for Use Appearance of Electric Stabilizing Gyroscope of the Sperry Type, on Ship- board. "A" is the Heavy Steel Rotor Wheel Driven by the intended for installation on a Fast Submarine Chaser. A is the Electric Motor "C ". The Gyro Usually Weighs Less Than One Per- Small Electric Motor Driving 24 -Inch Diameter Rotor at 4,000 R.P.M. cent of the Vessel's Gross Weight. It Prevents the Ship Rolling On Heavy Seas. speed wheel. The precession of such gyro- Government is to be congratulated upon closed as much as possible and, during scopes is taken care of automatically by a obtaining the services of so distinguished non -rush hours, ask passengers to use the special motor gear as shown in the sectional and accomplished a scholar as a co- worker rear entrance entirely, thus keeping the view. Here A is the heavy steel rotor to aid in solving the many diversified prob- front doors closed and contributing to the wheel, revolved on a vertical shaft B, by lems now besetting it. Mr. Hammer, who comfort of passengers. When conductors means of the squirrel cage induction motor was for a number of years an early asso- find it necessary to confer with motormen C. A heavy roller bearing D, carries the ciate of Thomas A. Edison in the develop- they should be careful not to stand with thrust load while the radial bearings E ment and application of the electric light, head and shoulders thrust out thru the transmit the gyroscopic loads thru the case has traveled extensively in Europe, and is open front door, but should rather step F to the gudgeon G, secured to the ship's or therefore thoroly conversant with electrical onto the front platfrom and close the car's structure. Great gyros of this type inventions and developments both in Great door behind them. and measuring 20 to 25 feet have been suc- Britain and on the Continent. Major Motormen, for their part, should remem- cessfully installed on large battle -ships to Hammer may be addrest in care of the ber that every time a brake is applied a prevent their rolling in a heavy sea, and Inventions Section, War Plans Division, certain amount of energy is taken out of thus provide a steady platform from which General Staff, War College, Washington, the train, and that to restore it a further the big guns could be accurately fired. The D. C. He received his appointment on consumption of power is necessary. When wonderful stabilizing power possest by even June 4th, 1918. a motorman, running thru a congested dis- the smallest gyroscope can be gleaned from trict, or where cars are blocked, keeps the fact that in computing the size of gyro "nosing up" by throwing his power on and for stabilizing a certain ship, the engineers THE VALUE OF A KILOWATT AND off to the jerky accompaniment of the figure on the complete gyro equipment to HOW TO SAVE IT. brake, he might as well be shovelling coal weigh about one per tent of the ship's total By John J. Dempsey out of the Company's bins, or money out displacement. Thus for a 500 -ton craft of the Company's pockets into a ditch. the gyro equipment would weigh but 5 tons Vice -President Brooklyn Rapid Transit The Company could really better afford to while for a 10,000 -ton battle -ship it would Lines. pay such a man to stay at home and not be only 80 tons or eight- tenths of one per WHAT is a kilowatt? work at all. cent. In terms of economy-of power Proper and economical operation requires The idea as here exprest is susceptible of saving-which is in a double sense a motorman to use his brake as seldom as many improvements to be sure. For one a burning issue to every industry and the possible consistently with safety and to thing it is not conceivable that we have nation at large today, a kilowatt repre- coast as long and as frequently as pos- found the most efficient form of air pro- sents the consumption of three pounds of sible consistently with his schedule. pulsion mechanism at all. Possibly the coal. So far as the public is concerned, it is air propelled craft of the future will have In the much -discust matter of heat, for perhaps not unnatural for persons who have propellers shaped like huge augers and instance: The operation of trains with- no sense of the amount of coal necessary worm their way thru the air-who knows? out heat requires four kilowatts per car to operate a system like the Brooklyn mile. With three points of heat on, it Rapid Transit to think, because we have requires between five and one -half and six what seems a great quantity of coal in our WILLIAM J. HAMMER NOW A kilowatts per car mile. Thus the heating of bins that that is sufficient to operate almost MAJOR IN U. S. NATIONAL a car requires 30 per cent of the power re- indefinitely and furnish ample heat as well. ARMY. quired to operate it. But that is only because they view the situ- It is with extreme pleasure that we can Obviously, then, it is the duty of every ation from the standpoint of their own announce that Mr. William J. Hammer, conductor to keep in mind the amount of coal consumption. If they stopt to think Consulting Electrical Engineer of New energy wasted in the opening and closing that it takes one and a half tons of coal York City, and who has contributed nu- of doors. With due care in this regard to run one five -car train from Union Square merous interesting electrical articles to the alone, a proper temperature could be main- to Coney Island and back and that two ELECTRICAL EXPERIMENTER in the past sev- tained in the cars on from one -third to such round trips consume more coal than eral years, has been appointed as a major one -half less power. the average family uses in a year, they in the U. S. National Army, and is at pres- During the cold weather conductors on would, if fair- minded, be disposed to with- ent located at Washington, D. C. The U. S. surface cars should keep the rear doors hold judgment.

www.americanradiohistory.com 230 ELECTRICAL EXPERIMENTER August, 1918 Reclaiming the U- Boats' Toll by Novel Salvage Operations

HE toll of sunken ships occasioned loud- speaking telephone running to the en- tical position on the opposite side of the by the advent of unrestricted U- gineer's post on the barge carrying the hull. boat warfare and "spurlos versenkt" apparatus, and in this way he does not have When the sand -hog has reached the posi- T promises to be a large one by the to turn or move his position while inspect- tion just mentioned, that is a vertical posi- end of the war, in spite of all of the ing a wreck, or when issuing orders to the tion on the opposite side of the hull, with anti- submarine devices and protective engineer for raising or lowering the tele- the water jet nozzle pointing upward to- means that have been promulgated and scope cables. Current for the electric ward the surface, as indicated by means of put into active practise. As we approach lamps is derived from a small dynamo a special electrical position-indicator at- the close of four years of the World War driven by the steam engine of the hoisting tached to the pilot, then the time has ar- with twenty nations locked in a titanic derrick on the barge, or it can be supplied rived when a buoyant float attached to a struggle to see whether Democracy or by storage batteries. light line can be shot thru the hose pipe Autocracy shall prove to be the "survival The telescopic searchlight just described by comprest air. The float emerges from of the fittest," the toll of the German U- is for the purpose of inspecting salvaging the nozzle of the sand -hog and, due to its boats and mines has mounted up into the operations, or for locating sunken ships, buoyancy it shoots to the surface of the hundreds of thousands of tons of ship- et cetera, while the illustrations at Figs. water and is made fast to a second barge. ping. Certain it is, from the present as- "B" and "C" show two novel schemes de- The sand -hog now has its propelling mo- pects of the one thousand and one prob- vised for the actual work of salvaging a tor started up, but in a reverse direction, lems of reconstruction which will come to submerged wreck. so that it backs up along the path it has our hands in the great aftermath of the The salvaging apparatus illustrated in previously pursued in crawling around the World War that we shall be confronted Fig. "B" was invented by Mr. John D. hull. It is then hauled into the starting with the unmistakable and undoubted need Hilliard, of Glens Falls, New York. This position for a second trip under the hull, of a greatly increased tonnage of ships to idea involves one of the most ingenious the line attached to the float having been carry much needed supplies to the various applications of electro- magnetism that we secured at both ends. The successive countries now being devastated. There- have encountered for some time. We operations are now easily understood so fore, as we cannot build ships sufficiently have described from time to time in the far as the sand -hog is concerned, and it is fast to catch up with the gigantic shipping ELECTRICAL EXPERIMENTER the famous past around the hull as many times as is requirements which are sure to face us the "wireless pup" and the "sound- controlled required in order to place the proper num- day after peace is declared, we will have dog," but the present electromagnetic ani- ber of cables or chains around the ship. but one other ultimatum-that is, to devise mal devised by Mr. Hilliard can only be Cables or chains of increasing strength and some means of accurately locating and rais- known by one name - "sand -hog,' -for size may be progressively pulled around ing the hundreds of ships, both large and sand -hog it certainly is. The series of under the hull, starting with the thin float small, which have been sunk by the enemy operations to be carried out in Mr. Hillard's line, which is attached at first to a light submarines. ship salvage scheme is somewhat as fol- cable and then a heavier one, et cetera. There has been a veritable flood of lows : Mr. Hilliard also provides a novel scheme patents issued in the past few years on He first provides an electromagnetic, embodying the use of buoyant caissons or many apparently feasible as well as many self -propelled double -wheeled pilot or tanks for raising the wreck. His method impractical schemes for raising sunken "sand- hog," as we may call it. The de- of getting these caissons into position about ships. In the present instance we shall tailed view of this most ingenious mechan- the hull is very ingenious and may be easily examine the claims of three recent paten- ism is shown at the right of Fig. "B." In understood by reference to drawing, Fig. tees who aim to provide apparatus for brief, this almost human electromagnetic "B." The first operation is to float the locating and raising the victims of the pilot comprises a small double -wheeled caissons into the proper position on the greatest submarine warfare ever con- truck or carriage attached to one end of a surface of the water. The cables from ducted. flexible hose or tube, thru which elec- the opposite sides of the submerged hull The first patent concerns a powerful tric control wires, etc., may be carried. It are secured to other caissons, so that when telescopic electric searchlight for locating is also possible to project a comprest air the respective cables are pulled upward by and inspecting sunken vessels. The details or high pressure water blast thru this flexi- the derricks and engines on the salvage of this scheme are indicated in illustration ble tube and out thru a nozzle fitted on the barges, they will act oppositely so to speak, "A," and were evolved by the fertile brain front of the sand -hog. The wheels of this with the result that the caissons above one of Mr. William Zach Pulliam. This in- curious looking self -propelled pilot are side of the hull will be pulled downward vention relates to submarine telescopes to caused to revolve by means of a hydro- into position, while those above the oppo- aid in salvaging sunken vessels and the static (water pressure) or electric motor, site side of the wreck will be pulled down like, and as the patentee states in his speci- controlled from above. Powerful electro- into their respective positions. In order to fications, the primary object of his inven- magnetic coils encircle the steel axled cause the caissons to sink easily their valves tion is to "provide a new and improved wheels, magnetizing them powerfully. Thus are opened so that water can be admitted; construction of telescope as well as a novel we see that a very curious and novel con- when they have been pulled down into manner of mounting it upon the wrecking dition is provided, viz., -that as the electric position about the submerged hull, the barge. Another object of the invention is motor tends to rotate the wheels, either water is blown out by comprest air thru to provide a telescope of the character backward or forward as may be desired, a hose connecting them with powerful air illustrated and having an. improved form of these same steel wheels are strongly mag- compressors on the barges at the surface. the objective fitted with a ring of power- netized owing to the effect of the magnet When all of the caissons or tanks have ful, incandescent electric lamps in such a coils just described, and the sang-hog will been blown out, and provided they have manner that a more efficient use of the tele- therefore, if lowered into the water near been selected properly as to size and num- scope may be obtained." the side of a submerged iron hull, tend to ber, their total buoyancy will be sufficient As is evident from the illustration, the crawl along the surface of the hull with- to raise the submerged wreck. It is best, collapsible telescope may be swung either out slipping. however, to have their total buoyancy a up or down in a vertical plane, or from Armed with this semi -intelligent mechan- trifle less than that just required to raise right to left in a horizontal plane, by virtue ism, the salvage engineers proceed to lower the wreck and to supply the small extra of its ball- mounted pedestal. The device the magnetic pilot and its attached cable lifting power required from the barge der- is quite a large affair as may be imagined, from the working barge in such a direction ricks in order to have better control of the and the operator sits in a seat placed on a that the sand -hog will take hold of the entire operation; otherwise the hull will rise carriage secured to the base of the tele- steel side of the ship and start working its too quickly. After the hull has been raised scope; in this way he may keep his gaze way down toward the keel. As the illus- it can have any holes in its plates repaired centered thru the telescope and objective trations at Fig. "B" clearly indicate, the by divers and the water pumped out. The lens, the latter having an opening at the sand -hog manages to cling to the steel sur- salvaged ship can then be towed to the center to permit the operator seeing thru it. face of the ship's hull, and by.means of the nearest dry-dock and repaired. Electric feed wires pass down thru the in- comprest air or water jet blast, a path is The scheme for raising sunken vessels terior of the telescope to supply current for cleared for it continuously thru the mud illustrated at Fig. "C," is due to Mr. the powerful electric lamps placed in front or sand in which the hull may lie. It is Charles B. Dawson, of Seattle, Washington. of the parabolic reflector which is mounted evident that as the magnetic pilot pro- Mr. Dawson's ideas are in some ways quite just back of the objective lens. gresses it will blow a channel or trench for elaborate, but he has them well worked out, In order to operate this large exploring itself clear around and under the bottom and while in some cases it may be rather searchlight, the operator is equipt with a of the hull, until it is once more in a ver- (Continued on page 280)

www.americanradiohistory.com August, 1918 ELECTRICAL EXPERIMENTER 231 VARIOUS SCHEMES FOR RAISING SUNKEN SHIPS

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(TT.THYNewSparks had reading disturbances affected all telegraph and fore you had uttered five words. His clear Wthe New York Evening World: telephone lines extending between Chi- blue eyes, lying deep in their sockets, He contemplated his old meer- cago and the eastern cities. On tele- sparkled with life and intelligence and what schaum pipe meditatively while graph wires of the Postal Telegraph Sparks did not know about electricity was with his long and lanky index Co. without regular battery being ap- mighty little indeed. I believe there is no finger, stained by many acids, he carefully plied at terminal offices, grounded lines electrical book in existence that Sparks rubbed a long, thin and quivering nose. showed a potential of 425 volts posi- had not devoured ravenously in his spare This was always a sign of deep, concen- tive, varying to 225 volts negative; the hours, while having lunch or else while in trated thought of the nose's owner. It also, disturbance continuing between 12:15 bed, in the small hours of the morning. as a rule, induced the birth of a great idea. A. M. and 9:15 A. M. His thirst for electrical knowledge was un- Again, and very slowly he re -read the ar- At Newark, N. J., in the Broad bounded, and he soaked up every bit of in- ticle, which millions that same day had read Street office a Western Union opera- formation like a sponge. Yes, and he re-

. . . The President of the Glorious French Republic Shouts Dramatically: "Messieurs . le jour de Gloire est Arrivé . . . VIVE -LA- FRANCE!!" -and Throws in the Huge Switch With its Long Ebonite Handle. . . .

casually, without a quiver, let alone, a nose tor was severely shocked, trying to tained it, too. In short,the young prodigy quiver. The newspaper item was simple operate the key, while long sparks was a living electrical cyclopedia and highly enough: played about his instruments. valued by his associates. No wonder Tesla NEW YORK, Aug. 10, 1917. -An Sparks rose excitedly and began pacing in three short years had made him superin- electromagnetic storm of great violence the cement floor of the vast Tesla labora- tendent of the laboratory. swept over the eastern section of the tory, totally oblivious to the fact that he Of course, Sparks' first name was not United States last night. Due to a bril- was sucking a cold pipe. The more he really "Why." But someone had dubbed liant Aurora Borealis,-the Northern paced about, the more excited he became. him with this sobriquet because of his Lights, - telegraph and long distance Finally he flung himself into a chair and eternal "But why is this,"-"Why, why telephone, as well as cable communica- began feverishly to make sketches on big should we not do it this way"-"Why do tions were interrupted for hours. No white sheets of drawing paper. you try to do that ?" In short his first telegraphic traffic was possible between "Why" Sparks had been just an ordinary word always seemed to be "Why " -it had to New York and points West. It was "Bug," an experimenter, when he entered be, in his unending quest for knowledge. impossible to work any of the transat- Tesla's great research laboratory at the And his "Why" was always very emphatic, lantic cables between 12:15 A. M. and beginning of the great war in 1914. Tesla explosive -like, imperative, from which 9:15 A. M., every one of them having . liked the keen, red- haired tousled boy, who there was no escape. "gone dead." The Aurora Borealis always seemed to divine your thoughts be- Ah, yes, his first name. To tell the honest Copyright, 1918. by H. Gernsback. All rights reserved.

www.americanradiohistory.com August, 1918 ELECTRICAL EXPERIMENTER 233 truth I don't know it. Last year in the "Sie, Müller," this to an orderly. gling in mid -air, -where was German pres- spring when I went up to the laboratory, I "Zu Befehl, Herr Leutnant," replied the tige coming to with such methods. Plainly thought I would find out. So when I finally young orderly as he came on the run, click- the men did not like such liberties with located the young wonder, behind a bus ing his heels together, hand at his cap. their honor, but orders are orders. They bar, where he was drawing fat, blue sparks "Versammlung, sofort," barked the chief, grumbled audibly and cast not very en- by means of a screwdriver, I told him that as he hastened Müller off to summon post couraging looks at their chief. Even his I intended to write something about him haste every man of the aerial squadron for parting shout: "Vorwärts-fiir Gott and and his wonderful electrical knowledge. the usual conference before the attack. Vaterland," failed to bring the usual cheers. Would he begood enough to give me his In less than ten minutes the thirty flyers Promptly on the minute of 10 fifteen real first name? were standing drawn up at military atten- flyers of the "Circus" rose, like a flock of He was watching a big fuse critically, tion before their chief, forming a half cir- big white sea gulls, heading in "V" forma- and in an absent -minded manner exploded: cle about him. Von Unterrichter's instruction towards the American lines. Von Unter- "Why "? That finished my mission. So tions were simple enough. This was a re- richter was leading his herd in a big for all I know his real name is "Why" prisal raid ; von der Halberstadt's death Fokker. He was out for blood and he Sparks. must be avenged, fearfully avenged. No meant to have it. His face was set, his But we left Sparks with his drawings, in quarter was to be given. jaws clenched like a vise. Hate was writ- the laboratory. That was on a certain ten in large characters over every feature evening last falL of his Why didn't - To be exact it II these Dollar was about 11 111 II 1111111)1111IIIIIIIIiIIP1IIIIII11111111111111111 111111111111 IIIIIII II III MIEffig face.... 10 o'clock. At 10:05 Tesla accompanied eg jäger stay home and mind their own busi- by two high Army officials strolled into the IN THE SEPTEMBER "E.E." ness chasing their dollars? What right did laboratory where Sparks was still feverishly YOU WILL FIND: N they have in this fray, anyway. "Elendige engaged with sketches lying all about him. "New Aerial basso to Destroy Ene- Schweinebande," he spoke out loud, to bet- Tesla who was working out a certain ap- my Aeroplanes," by H. Gernsback. ter vent his overpowering hate. paratus for the Government had dropt in "Recent Electrical Ideas Applied to But where were the Yankee Flieger to- late to show Major General McQuire the N Submarines and Torpedoes." day? The Baron's "Circus" was up one result of six weeks' labors. The apparatus "Telephoning Directly To and From thousand meters and less than a mile away had been completed that day and the Gen- Moving Trains." from the American first line trenches, but eral, a military electrical expert, had come "A New Wave Motor That Uses M still no machine in sight, either American over specially from Washington to see the the Energy in Every Motion," by E. f or French. Strange. Quite an unheard of "thing" work. D. Stodder, an expert on Wave occurrence. Afraid? "Unsinn," he mut- But before Tesla had a chance to throw Motors =M tered to himself, they were not the sort to in the switch of the large rotary converter, "The Einthoven Galvanometer -Its M- be afraid. Von Unterrichter knew that. Sparks had leaped up, and was waving ex- Theory and Construction Details with For the first time he felt a vague sort of citedlyra large drawing in Tesla's face. He Photos of Instrument Actually Built," uneasiness creeping over him. He could gushed forth a torrent of sentences, and - by Samuel D. Cohen. not understand. There was not a Flieger for fully five minutes Tesla and the two "Coney Island's New 1918 War anywhere in sight. None on the ground Army officials were listening spell -bound to m Feature-`Over There' -Read How M. either, as he scanned the vast saucer below the young inventor. For a minute or two Electricity Works the Whole Show," him thru his Zeiss. Was it a new trick, the three men were speechless, looking awe- by George Holmes. was... struck at Sparks, who having delivered E `Artificial Diamonds and Rubies- Before he finished his train of thought, himself of his latest outburst, now became N How They Are Made in the Electric his engine stopt dead. Cursing volubly he normal again and lit up his still cold pipe. Furnace." made ready to "bank" his machine in order It was Tesla who first found his voice. "The Phenomena of Electrical Con - to volplane down behind his own lines. He "Wonderful, wonderful. Absolutely won - m duction in Gases V-Weighing an congratulated himself that his engine had der-ful, Sparks. In a month you will be not stopt later while over the enemy's N Ion," by Rogers D. Rusk, M.A. ffi the most talked of man on this planet. And " An Electrical Laboratory Switch - lines, but his pleasure was short -lived. his idea is sound." This to the General. M board -How to Build a Real One." For he suddenly became aware of the fact "Absolutely without a flaw. And so sim- by Harlan Danner. that there was a supreme quiet reigning all ple. Why, oh why! did I not think of it n "Glass-blowing Lessons-How to about him. Why did he not hear the loud before? Come, let me shake the hand of H- Heat and Bend, As Well As Build roar of the other fourteen engines, now America's youngest and greatest genius!" N Glass Chemical Apparatus-Part I," that his own engine was quiet? Looking Which he did. Mby Prof. Herbert E. Metcalf. around he perceived with horror that every There then followed an excited thirty - "Ohm's Law Applied to Alternating one of the fourteen machines of the "Cir- minute conversation with the two army N Current Circuits -A Clear Exposition cus" had simultaneously "gone dead," too, men and an endless long distance all of them now talk with M of All the Usual Problems," by Arno volplaning earthward. the War Department at Washington. Then g A. Kluge, Instructor in Radio, Uni- Sick with an unknown terror, von Un- there was a rush trip to Washington by versity of Nebraska. terrichter made a clumsy landing in the Tesla and Sparks, conferences at the War "New Direct Reading Radio Chart midst of his other flyers, all of them pale, Department, and finally a few days later Which Solves All Calculations in some shaking, some with a strange animal Sparks went to the White House and was Wave -length, expression in their eyes. What unknown, presented Inductance and Capac- to the President, who was highly rI ity," prepared by a Marconi Radio En- invisible hand had with one stroke disabled enthusiastic about the model which Sparks gineer. the fifteen engines, one thousand meters and Tesla demonstrated to the head of the above the ground? M "Popular Astronomy - Third Nation. Still later there were certain rush Paper," by Isabel M. Lewis. "Himmelkreuzdonnerwetter," shrieked orders from the War Department to the "How and von Uhterrichter jumping to the ground, General Why of Radio Appara- Electric and Westinghouse Com- tus-Part X," by H. Winfield Secor. near his airdrome. "I . . I . . cannot" panies for many big, queer machines, and here his voice broke. For the first these same machines 11111111111111111111un 41VI111gI11 u11"IIRIIIbIIlUt111111 were shortly I 111111E11111 IIIIIIIIIIIIII1Il1 NIIIIIIIUIh1111 10 time in his life the young Prussian was But here the Censor bids us an emphatic speechless. He then stamped his foot in a "Halt." One may not even now divulge "Dieses Amerikanische Gesindel!"-here frenzied fury, but finally gave vent to a certain military information. You appre- his voice rose to a shrill pitch, "must be full round of cursing, as only a Prussian ciate that. taught to respect us, as never before. The can curse. At last he collected his senses * * * * orders are to bomb every American base sufficiently to look for the cause of the hospital within Baron von Unterrichter's flying "Circus" the sector...." mysterious occurrence. It only took five war getting At this several of the men recoiled in- minutes to find it. His mechanician pointed ready to bomb a certain Amer- voluntarily, ican depot behind the lines. The Americans which did not escape the keen to the magneto. of late had shot eye of von Unterrichter, who now incensed "Kaput," he said laconically, if not gram- down entirely too many to blind fury, matically. of the Baron's flyers. Only yesterday von by this show of "softheart- der Halberstadt edness," as he put it, exhorted his men in "Auseinander nehmen," commanded the -a German ace himself - his harshest possible terms. chief. and one of von Unterrichter's closest "And as for friends had their flyers, you must not give quarter. It took the deft mechanician been downed, and killed right You but a minute inside of the German lines. must not be satisfied with disabling to take the magneto apart, and to So the Baron their machines. Kill them! with- was out for blood this sunny morning. As Schiesst die draw the armature. He gave it one look he put it: Lumpen zusammen! Pump nickel into and with a sickly smile uttered: "Verdammte them, if you see that they may land un- "Ausgebrannt, Yankee Schweinehunde,* we harmed" Herr Leutnant." Herr will show them who is master of the air -this in direct violation of all Leutnant took the armature into his own hereabouts," flying etiquette -a thing abhorred by any hands and inspected it critically. shaking his fist at the Ameri- decent flyer Sure can lines beyond. a;. a rule. It is bad enough to enough it was burnt out, if ever there was have your machine shot down, but "sitting a burnt out armature. Perhaps fused For translation of foreign terms see end on a disabled enemy's tail," story. of this and pouring would be a better term. The armature was machine gun fire into a helpless man, strug- (Continued on page 267)

www.americanradiohistory.com 234 ELECTRICAL EXPERIMENTER August, 1918

Electricity and the Range - Finder in War s many people are aware, the matter on your superstructure and gun deck, pos- left prism telescopes can be trained on the of determining accurately the range sibly disabling your own battery. distant object, and the refracted rays from between a certain gun or battery of Thus we see that the man at the range- the prisms are past thru a pair of objective A guns and the enemy target, is a finder has a very important mission to lenses in the manner illustrated. These very important factor in all military fulfill, when he straps the head 'phones and right and left rays pass along thru the center of the blackened range -finder tube and meet in the center where there is positioned two central reflectors. At this juncture it is well to note the two views shown in the circles at the bottom of Fig. A. These two views show the image of a distant target (a church) as it appears in the eye -piece of the range -finder, before the right and left prisms are adjusted to "coincidence" and 'after coincidence," the latter or right hand view being the one observed by the range -finding officer at the point where the instrument indicates on a specially calibrated dial the correct range in yards. As will be noted from Fig. A, the upper semi- circular image is the one reflected by the left hand prism. A dividing line separates the two images, and in the present case the instrument is adjusted until the tower of the church slides along toward the left until it is exactly in line with the remaining portion of the tower appearing in the lower image. So much for the physical action of the "one -man" range- finder. But this does not tell us yet just how the range is determined, excepting that we have learned that when the images coincide, that the instrument indicates the range in yards on a calibrated dial. Probably we will do best to go back a few years to the time of the Boer War in South Africa. At that time the English Army had considerable range -finding to do down among the Kapjes of "Oom Paul's" land. Briefly explained, the "two -man" range -finder then used works after the Photo by Central Nan Photo Service fashion illustrated in Fig. B. It must be Getting the Range. Jackles on an American Battleship Getting the Range by Means of the "Range- finder." The Man with the Telephone Apparatus Attached to His Head Controls the considered before going further, that every Bighting of the Gun and Telephones the Men In the Turret When the Object Is In Range. (Continued on page 278) and naval maneuvers. Not so many years transmitter on, and pro- ago when the range of artillery was quite ceeds to turn the lenses J insignificant compared to that of today, the and other paraphernalia parizoh,fol,Range fiinder Central ,. matter of range-finding as it is known, was fitted on the range- finding {'tube afRnawn en/h -' Rat,lec.ór abl"ec/iva '.. an unknown study. All that the officer in tube, for it is he who con- charge of a gun battery had to do in trols the sighting of the those days was to check up the first few big guns. It is he who it aCleet, re fye ! Ra del emeibg shots fired and by watching the effect and determines the range or 'Le? prism fides_ R, the point hit by the projectile thru his changes in range, etc. He dru pnlm. telescope, or in many cases simply with the telephones these figures to Image reflected . 0614Cias jeer) rn naked eye, the particular gun firing the a staff of engineers who by left p{hm. shots could be readily elevated or lowered are in constant touch with ìaG .i so as to change the trajectory of the pro- the "gun pointers" in the jectile. But in the past twenty-five years /malte reflected turrets below. A single by right prised the hit and miss principle of range -finding range-finder may be has been done away with, and a number of quickly disabled even in a Before CatceEice more or less accurate range- finding instru- long range engagement, ments developed, some of which are very and so every war -ship car- .., ingenious indeed, and extremely accurate ries at least two range- for comparatively long ranges. finders. The large super- The photograph herewith shows one of dreadnoughts carry as -B- p..-0¢/ed -C- Uncle Sam's latest types of accurate range - many as a dozen on board, finding instruments installed on board a some of them being situ- modern dreadnought. The Jackies are ated on top of the steel shown in the act of determining the range fire -control masts, while anroam angle measu of an object which has been selected as a others are located in less m \ ea q \ and inkrprefed b> target for the ship's giant guns, several of conspicuous locations. "i range finde.- which can be seen in the background pro- The diagramatic illus- truding from their turrets. The operator tration herewith will help peering so intently into the eye-piece of the to explain how the mod- \ range- finder, and who is wearing a pair of ern range -finder does its l /Norm base Mal sensitive telephone receivers as well as a work. Referring to Fig. x'- : ? reguiiednilhzmm ¡ Sa. 7';', rove finder transmitter strapt to his person, is one of the A, we have a sectional ° r ia most important men in the crew of any view of the present day fighting ship whether large or small, for if "one-man" range - finder. trigkOabwntr he makes an error in reading the dials of This comprises two prisms the range -finder, then the enemy may escape known as the right and being hit. As becomes evident, time is the left prisms, which are The One mon Ronge finder essence of every naval engagement, for in made adjustable by means a few minutes time the enemy if not dis- of thumb screws protrud- f- abled by your own guns will in all proba- ing from the Details of Range -finder and How the Range Is Automatically casing of the Calculated When the Base and One Angle of a Right angled bility plant the major part of a broadside apparatus. The right and Triangle Are Known.

www.americanradiohistory.com August, 1918 ELECTRICAL EXPERIMENTER 235

WOMEN TO LEARN X -RAY WORK. trained men which of necessity cripples to ties of the women folk in the radio service, IT seems that with the war's progress, quite a large extent the wheels of industry. including the training of drafted men. Now and its constant inroads upon our male Women have been excluded from the regu- a new branch of scientific study is about to population, it behooves itself upon the lar service of both the Army and Navy be placed at their service and one that will women -folk who are left at home to in with a few exceptions, such as Yeoman, etc., yield a substantial remuneration for the some way fill these vacancies, so that the speed of war preparations may be kept up to the highest standard. Also it is to be noted that a steady drain is being made from the ranks of technically

MOBILE X -RAY NOW USED AT FRONT -LINE TRENCHES. The Committee on Public Information, Division on Woman's War Work, issues the following: The X -ray is now carried to the front- line trench for the benefit of wounded soldiers, so that no time may be lost in ascer- taining the condition of wounds. The Army Medical Department has developed a mobile X -ray outfit, carried on a standard Army ambulance slightly modified. This outfit includes an X -ray table, a dark room, also a complete set of apparatus for the localization of foreign bodies. Fully as expert work can be done with this mobile outfit as in any base hospital X -ray department. Its use in the field makes it possible for the surgeon at the front to send a complete report of a soldier's condition when a man is transferred to a hospital back of the lines. ELECTRIC MACHINE MAKES FIFTY YARDS OF BAND- AGES A MINUTE. The machine being operated by this nurse is expected to revolutionize the making of gauze bandages. It is the invention of J. A. Butler, of Boston, and has been installed in How Young Women Are Being Taught X -ray Technique at a New York College. They Are the New England Surgical Dressings Com- Put Thru a Rigid and Thoro Course Which Fits Them for Service with Uncle Sam's Fighting mittee workroom. Legions Whenever They Are Called. According to reports the machine is work - ing very satisfactorily. It produces two but it is undoubtedly a fact that their ser- time and expense of the course, while at sizes of folded bandages, one four inches vices would be much in demand in civilian the same time aiding the country in its and the other three inches wide. They are walks of life were they properly trained to fight for Democracy. folded four or eight times as desired. The fill the constantly growing vacancies. The course is a special term from June machine is capable of turning out 50 yards Foremost in the ranks of institutions 3rd to August 10th in X -ray work. So far of bandages in a minute depending on the who have started in the work of training there have been several hundred requests skill of the operator, which is a great deal women for war work may be mentioned for admission to the course but the school faster than the usual method of hand manu- the Hunter College of New York City. We will only be able to handle a limited number facture. have published from time to time the activi- of classes. There will be ten students to a class and in making up these classes preference will be shown to those who have been nurses or are acquainted with medical practise. This was only decided upon after due consideration, and it was shown that those already having some training would be all the quicker able to fill the many vacancies at present. The installation of the apparatus will be taken care of by a large New York X-ray apparatus concern and the cost will be near the three thousand mark. It will be of the best and capable of a very wide range of work. i. The course itself will be under the super - vision of Dr. Raymond Bartlett Earle. Dr. Elsie Fox, Roentgenologist in charge, City Hospital, will be the X -ray instructor, and an advisory board of prominent doctors and surgeons will complete the list. There will be an afternoon course and also one in the evening consisting of the following subjects: X-ray, including the action, care and operation of the machine, anatomy, French conversation and physics lectures, after which will come the hospital observation in which the students will act as assis- tants in the taking of actual X -ray photos. The course will be very thoro, making it necessary for one undertaking it to apply oneself conscientiously to the serious work in hand and none but those attaining a mark of eighty per cent or more will receive a certificate. It is not to be doubted that all taking it up will have the ambition Photo ® by Underwood & Underwood to make good in order that the government This Remarkable Electric Bandage Maker Turns Out Fifty Yards of Bandage a Minute. I Produces Two Sizes of Folded Bandages, One Four Inches and the Other Three Inches Wide. may call upon them when necessary.

www.americanradiohistory.com 236 ELECTRICAL EXPERIMENTER August, 1918 How Birds Take Their Own Pictures Electrically By Dr. E. BADE

T is difficult to take good animal pic- like arm. The "V" shaped piece of metal into the circuit. This button is placed at tures in the open for the simple reason fits loosely between the wooden support a little distance from the camera but still that the camera sees differently than and slides with its heavier end in the within sight of it. When the operator sees dip human eye. The various colors of groove. When the twig is pushed down- a bird advancing towards the contact box nature do not sensitize the film in pro- ward the lighter end of the metal touches he presses the button and the picture of portion to their light values, and since the the flattened wire. This closes the circuit. the animal will be taken, provided that the film is color blind, it interprets little more The camera is placed upon a small table birds jumps upon the twig. When he sees than light and dark. or an especially contrived tripod upon which that other birds are in the vicinity which he

Note the Natural Position Assumed by This Bird In Taking His Own Photo.

Only One of Many Accurate Bird Photos Taken with Dr. Bade's Outfit The difficulties of approaching the animal the electro- magnets are fastened. The does not desire to photograph, the push one desires to photograph can be sur- camera used in this case was a Graflex, hav- button is released. Should the bird hop mounted with the following electrical de- ing a push button which releases the shut- on the twig, the circuit will not be closed, vice. This contrivance consists of three ter. A large angle iron was taken, a knob and no picture will be taken, since the cir- dry cells, an electric bell, a small electro- placed at one end, and a weight at the other. cuit at the push button remains open. But magnet, and a contact or switch box. The The knob was adjusted so as to come into press the button and the picture of the bird contact box consists of a strong wooden contact with the push button, while the is instantly taken. base upon which is screwed a support for weight at the other end of the iron was in- Of course, this device must be placed a movable scale -like contrivance. A strong creased until a slight pressure released the where from previous observation birds have wire rod, or a long nail is used for a pivot. shutter. The magnets were then placed been frequently seen. These places are One arm of the scale extends about four upon a projecting support so that they came usually found near or at bird -houses or inches. At the extremity of this arm a within an eighth of an inch of the angle bird- baths. The birds can also be attracted light twig is fastened. Just behind the iron. to certain places by food. This is placed pivot the other arms slopes gently down- The camera is now focust upon a twig out a few days before the camera is used ward and ends in a box -like receptacle into or any other suitable object fastened to the so that the birds will become accustomed to which stones, pieces of iron, or lead are arm. The instant a bird hops upon the twig this contrivance. placed, so that this end little more than the circuit is closed and the magnet is en- counterbalances the other arm. The - first ergized, instantly drawing the angle iron BIG TURBINE FOR NEW YORK. arm, to which the twig was fastened, also downward. This releases the shutter and The United Electric Light and Power carries the contacts which only closes the the photo of the bird is secured. Company of New York City has recently circuit when a bird is sitting on the branch. It will be found advantageous to intro- placed an order with a large Pittsburgh As can be seen from the accompanying duce an electric bell into the circuit as it electric manufacturing company for a 22,000 drawing, the wires carrying the current are instantly rings when a picture has been kilowatt turbo -generator set. The gigantic here interrupted and flattened. One end of taken, thus enabling the operator to reload generator will be rated at 25,900 kva. at the wire is rounded into a shallow groove, the camera at once. 85 per' cent power factor, 8,000 volts, 3- while the other is flat. Just above the two It will be found that certain birds fre- phase, 62% cycles. It will be direct -con- flattened wires is a "V" shaped piece of quent certain places more than others. nected to a steam turbine. The order copper, supported by a piece of wood which Now, in order to secure a variety of birds, includes a 40,000 sq. ft. surface condenser in turn is fastened to the movable scale- an electric push button is also introduced and the usual auxiliaries.

www.americanradiohistory.com August. 1918 ELECTRICAL EXPERIMENTER 237 The Electrical Women of England By ALBERT II. BRIDGE (London Correspondent ELECTRICAL EXPERT MENTER.) QUITE early in the war it became of electric lamps in which substitutes for is but an illustration of the deftness, skill, obvious to the British Ministry o f platinum formed a special feature. But ability and willingness that women are Munitions that if fighting men where in the old days ten women were en- demonstrating every day in a host of other were to be released from industry gaged in electrical manufacturing activity, departments of industry directly or indirect- without reducing the output of there are now thousands of them and the ly connected with munitions production. war requirements, women must take their number of operations, or classes of service The position up to date is: there are places. rendered by them, have increased corres- 950,000 women engaged on munitions prod- Those of us who have been more or less pondingly. ucts! Mr. Ben H. Morgan, who was for closely and sympathetically observing the By courtesy of the Ministry of Munitions two years Dilution officer under the British course of such matters all along, know the writer is able to illustrate some typical Ministry of Munitions gives us to under- something of the difficulties that have lifted examples of what English women are do- stand that they are turning out nearly one - their ugly forms and spread themselves ing in electrical works. Before the war we third of the total output! across the path of progress; we also know regarded with distinct amusement a novel with what tact, adaptability and determina- departure in American electrical practise tion each new critical situation has had to when we read in the electrical press that at be negotiated. Prejudices from employers some small out of the way station in the NAVAL AVIATION WIDE OPEN and prejudices from workmen, had to be States a woman part -proprietor ran the FOR YOUR TRADE. broken down a bit at a time, and all the plant. We even looked upon it as a f reak- "Here's a chance tv enroll in the United while headway had to be made with the perhaps you Americans did so too -but States Naval Reserve Force and work at suitable training of educated and other such is not the case today. We now have your own trade. women. Only the most imperative demand women working in some of the largest The naval aviation section needs a great of absolute necessity made the change pos- power stations in the United Kingdom. Ex- number of men immediately. Good ratings sible so that it may be said that under the perience with them on the whole is not and good pay are possible for qualified men. influences of compulsion we have been able unsatisfactory, yet I believe I should feel Here is the list of ratings and the neces- to secure practical experience of inestim- pretty safe if I had to predict what would sary trades. able engineering value which we might not happen in this particular connection after Machinists' Mates -General machinists, have had in decades of normal operations. the war. automobile mechanics and assemblers, tool- Gradually our women were brought un- One of the accompanying photographs makers, diemakers and similar mechanical der training for special operations, and shows a woman engaged in electricity trades. work to which women had never previous- works service -in charge of a switchboard ly put their hand was soon proved to be for 500 kilowatts. I recently inspected the Quartermasters- Cutters and cloth fitters, well within the compass of their strength most complete and educative official collec- upholsterers, canvas workers, painters, tent and their adaptability. In practise such re- tion of specimens of electrical work the riggers. sults have been obtained as should demolish product of woman skill and labor-and I Carpenter's Mates -Woodworkers of all absolutely all prejudices so far as individual saw photographs of women engaged in kinds. or ultimate efficiency is concerned. Just charge of a 1,000 horsepower steam engine, Blacksmiths -Toolsmiths, forge men, fur- now, when still more men of military age another attending a 300 kilowatt direct nace men, etc.

How the Women of England Are "Doing Their Bit" by Building and Operating Electrical Machinery. Left-Winding A. C. Induction Motors; Center -One of the Many Central and Sub -station Switch -board Operators; Right-Assembling Small Motor Commutators. are leaving the bench for the camp and the coupled engine set, others building small Shipfitters -and all kinds of sheet metal trench, experience and necessity are work - commutators, operating presses for arma- workers. ing hand in hand to that end. ture work, assembling ironclad switchgear, Coppersmiths It was of course, no new thing for wo- erecting switchboards, driving 40 ton cranes, - men and girls to be engaged upon many driving electric trucks, conducting electric Applicants must be American citizens small electrical manufacturing operations. making from 18 to 35 years of age. Draft regis- welding operations, electric con- trants will be accepted upon presentation of Years before the war the writer had wit - tact mines, making parts for internal com- nest their efficient employment in electric bustion engines, sparking plug parts, mag, a letter from their local boards. wire and cable factories, in armature wind- netos, lampholders, lighting switchboards Men of the foregoing trades will be sent ing work, electric lamp manufacturing and for mechanical transport work, etc.,-in- to school for special training. testing, in conduit and switch work, and in deed a mere catalog of the different occu- Applicants may enroll at 51 Chambers the making of numerous small accessories. pations in which they are engaged, tho it Street, New York, or at any Naval Re- In one case in London a factory was run would prove their multitudinous and multi- cruiting Station in the United States. for a time in which crippled girls, ex- farious nature, would be monotonous. Yet There you are. Now sign up and help clusively, were engaged in the manufacture what is happening in the electrical world the Navy Airboats get the U- boats."

www.americanradiohistory.com 238 ELECTRICAL EXPERIMENTER August, 1918 Popular Astronomy THE GASEOUS NEBULAE-SECOND PAPER By ISABEL M. LEWIS Of the U. S. Naval Observatory THERE exists in the heavens, at a tory nebulae, and the mysterious spiral ing to the first law of spectrum analysis conservative estimate, from half a nebulae. Members of the first two groups such a spectrum is characteristic of incan- million to a million nebulae that are are strictly gaseous in their nature, but descent gases shining only by their own visible in the greatest telescopes. A the last group, which includes by far the light under low pressure. What these very few of these, notably the Great greater number of all the nebulae, has gases are can be determined from the posi- Nebula in Orion, the Great Spiral Nebula characteristics that seem to point to an en- tions of the lines in the spectrum, since in Andromeda and a particularly bright tirely different origin. to each chemical element belongs always the same line or set of lines in the spectrum. It has been found that all gaseous nebulae are composed of hydrogen and helium gas and an unknown gas found only in gaseous nebulae and named for that reason nebulium. This peculiar gas is characterized by a bright line in the green part of the spectrum that gives a greenish tinge to the gaseous nebulae. They are for this reason sometimes referred to as the green nebulae to distinguish them from the white or spiral nebulae. It is believed that the presence of nebulium may be due to some form of electrical excitations existing in extremely rare gases. The irregular nebulae are, there is every reason to believe, the primordial stuff from which the stars are made. They fill a tremendous volume of space but possess very low density and small total mass. This is evident from the fact that they are certainly as distant as the stars, with which they are frequently associated and yet they cover an apparent space in the heavens that would be filled normally by hundreds, or in some cases thousands of stars. When we consider that the average diameter of a star is about a million miles and that within a sphere whose radius is, according to Newcomb, 412,500 times the radius of the earth's orbit (the radius of the earth's orbit being 93,000,000 miles) there exists but one visible star, on the average, we begin to realize how enormous must be the volume of space filled by the vast irregular nebulae. Were they not of small mass and low density, their gravitational force would be so great that they would draw to them all the neighboring stars. Estimates of the densities of the gaseous nebulae are usually placed between one

An Irregular Nebula In Cygnus (N. G. C., 6960). Photographed by G. W. Ritchey with the two -foot reflector of the Verkes Observatory.) This Nebula Appears In One of the Denser Portions of the Milky Way. Note That It Extends Across Regions Occupied by Many Stars, a Proof of Its Tremendous Size. nebula in the Southern Hemisphere can be In fact, it may turn out that the spiral faintly distinguisht without telescopic aid. nebulae are not nebulae at all. This most So extremely faint are the great majority, puzzling group which has been the subject however, that it requires all the light -gath- of an unusual amount of investigation and ering power of the most powerful tele- discussion in the past few years will be scopes, aided by photographic exposures of .treated of separately in another article. several hours' duration, to bring out the We will consider here only the true gase- details of their varied and intricate struc- ous nebulae -the planetary and irregular ture. nebulae. Altho the nebulae are most diversified in Gaseous nebulae can be distinguisht by A Typical Planetary Nebula -Note Strong their general appearance, they may all be the nature of their light which gives, when Central Star -like Condensation. (Photo- classified into three groups: the vast irregu- examined with the spectroscope, what is graphed with the Crossley Reflector of the lar nebulae, the comparatively rare plane- known as a bright -line spectrum. Accord- Lick Observatory.)

www.americanradiohistory.com August, 1918 ELECTRICAL EXPERIMENTER 2 39 hundred thousandth and one millionth of stationary in space. This brings us to the trophe, and that they have an unusual the density of the earth's atmosphere. It most marked point of difference between origin. Recent observations show that has been found very difficult to explain how the irregular and the planetary nebulae, some of them are in rapid rotation. The the luminosity of the gaseous nebulae is that of their motion thru space. The temptation to connect these in some way maintained under the conditions of ex- irregular nebulae are the most slowly mov- with the temporary stars or Novae (new tremely low temperature and pressure that ing of all celestial objects, being practically stars) that apparently owe their origin to must prevail everywhere, except in the at rest or simply drifting thru space, while some celestial encounter is very great, es- more central portions of the nebulae. It the planetary nebulae are to be classified pecially since the Novae are observed at is believed that the light of the gaseous among the most rapidly moving objects in a later stage to be surrounded by a nebu- nebulae must be due partly to some form of electrical excitation. It is not understood, moreover, how the nebulae can show the complex structure that characterizes them under the force of gravitation alone. Some other forces such as electrical repulsion or radiation or light pressure must be at work as well. Irregular and planetary nebulae bear a strong resemblance to each other in some respects, yet differ radically in others. Both types show a marked preference for the plane of the Milky Way, the fundamental plane of the sidereal universe. They are found most frequently where the star clouds are densest, and they are as often as not associated with stars that are classified as young stars. They are never connected with stars of an advanced type. The stars enmeshed in the gaseous nebulae are the helium stars, or as they are frequently called the Orion stars, because they occur in such great numbers in the Great Orion Nebula and its extensions. They are characterized by their extremely low density and intense blue light. Great star groups such as the Pleiades and the chief stars of the constellation Orion are sometimes enwrapt in one vast irregular nebula which often condenses locally around conspicuous stars of the group. At the very center of the Great Orion Nebula is a multiple star of six components that is beyond a doubt physically connected with the Great Nebula. All the conspicuous stars of the Pleiades are surrounded by a faint nebulous haze which appears to shine partly by reflected light from these stars and partly by its own luminosity. Portions of these great irregular nebulae are non -luminous; dark streaks and lanes are frequently observed in the bright gaseous nebulae singularly devoid of stars as if dark absorbing matter shut off the light from stars lying beyond. Observations of the Great Orion Nebula have shown a whirling motion of its parts, tho as a whole this vast nebula is almost

The Great Nebula In Orlon (Photographed by G. W. Ritchey with the Two -foot Reflector of the Yerkes Observatory). This Is Generally Considered to Be the Finest of all Nebulae as Well as One of the Most Magnificent Objects in the Heavens. The Dis- tance of the Great Nebula Is Uncertain, Tho It Cannot Be Less Than Several Hundred Light Years. According to Recent Investigations by Prof. W. H. Pickering, the Nebula Is 6,250 Light Years Distant and Its Diameter, Including All the Ramifications That Envelope the Entire Constellation, Is 1,700 Light Years. Upon This Assumption the More Central Portion Photographed Above, Showing the Multiple Star Theta Physically Connected with the Nebula, Has an Extent of Nearly One Hundred Light Years or More Than Six Million Times the Distance from the Earth to the Sun. The Entire Nebula Forms One Seething, Tumultuous Mass of Incandescent Gases Whose Density Has Been Estimated as Low as One -millionth of the Density of the Earth's Atmosphere.

the heavens, their speed averaging much lous haze bearing a strong resemblance higher than that of the stars. The plane- in composition and general appearance to taries are also extremely ;mall as com- the planetary nebulae. pared to the irregular nebulae, receiving The spectrum of the planetaries is, on their name from their resemblance to faint the other hand, very similar to a certain planetary disks. They are usually asso- rare class of stars known as Wolf -Rayet ciated with a single star or show a star- stars. These stars, the Novae and the like condensation at the center. There are, planetary nebulae are all closely confined The Ring Nebula In the Constellation Lyra few these ob- to the plane the Milky Way and (Photographed by G. W. Ritchey with the moreover, comparatively of of some Five-foot Reflector of the Mount Wilson Solar jects, not more than one hundred and fifty relationship between the three classes of Observatory). One of the Finest of the An- being catalogued up to the present time. objects may be traced as a result of further nular Nebulae, a Variety of the Irregular seem indicate observations. Type of Gaseous Nebulae. Note the Central The latest observations to Star, Which Is Physically Connected with the that these small nebulae have arisen as a We may now briefly summarize the. Nebula. result of some celestial collision or catas- (Continued on page 280)

www.americanradiohistory.com 240 ELECTRICAL EXPERIMENTER August, 1918 The Phenomena of Electrical Conduction in Gases PART IV -WHY IONS DISAPPEAR

By ROGERS D. RUSK, M. A.

THE behavior of the electrically tion of the above two coefficients, has been have reached a steady state and the number charged particles of a gas is at times done quite recently by the world's leading of ions will be a maximum. almost magical in nature. Unseen Scientists define the rate of recombination forces may suddenly produce them do and other unseen forces may as sud- mathematically as and put it equal to denly make them disappear. The scientist - O SO O dt who wants to know whether or not a gas an' where a is called the coefficient of re- will conduct electricity must first know combination and "n" is the number of ions whether there are any ions present in the O O O of either sign present. It can be seen that gas. If he wants to know just how much a is merely a constant which expresses the electricity will pass thru the gas he must (0) neutral molecules relation between the rate of recombination also know how many ions have been pro- and the number of ions present. As the duced and how many have disappeared. It amount of current which will pass thru a is a well -known fact that if an ionized gas O O gas depends upon the number of ions pres- is allowed to stand for some time it will 0 ent in the gas and the number of ions de- in some way lose its ions and its power to o pends upon the rate of recombination, then conduct electricity. This seemingly mys- 0 0 the current depends on the rate of recom- terious phenomena, however, can be very bination. easily explained by two words -diffusion (h) charged ions One of the earliest determinations of the and recombination. coefficient of recombination was made by Diffusion is the scattering of ions and E. Rutherford in 1897, by the use of a their migration to a conductor where they O O "P.!! metal tube similar to the one shown in lose their charge and recombination is the Fig. 2, by blowing a current of ionized air reuniting of the ions of a molecule again. O ..o thru it and measuring the conductivity at The numerical figures which represent the OJ different distances along the source. For rates at which these processes continue are instance if the current from electrode C to called respectively the coefficient of dif- (C) ions recombining E, is one -half what it is from A to E, then fusion and the coefficient of recombination. f/g.1 half of the ions have disappeared and the In obtain these coefficients or time taken for order to Showing Arrangement of Neutral Molecules, them to disappear was the rates of disappearance of the ions it is Charged Ions and Ions Recombining. time for the gas to travel from A to C necessary in some way or other to count down the tube. The only measurement it the ions or determine their relative num- is necessary to take are the currents thru bers at different times. An ion, however,- physicists, including J. S. Townsend and the gas at A and C, and the rate of flow is far too small to be visible even in the J. J. Thomson of England. of the gas from A to C. The rate of re- Recombination is a very natural conse- combination has been found to vary with quence of ionization and as its name im- the different methods of producing ions, plies, means the recombination of positive and negative ions just after they have been formed. For instance when a neutral molecule experiences the force of some ionizing agency it is torn asunder and forms two equal and oppositely charged ions ; now these oppositely charged particles attract each other according to the laws of electric attraction, and if they are not suddenly driven far apart by some force, this attraction will cause them to reunite and thus form neutrally charged molecules again. This can be shown diagramatically as in Fig. 1, where each stage of the action is ' . /nsu/olor shown. In any ionized gas then, where there are equal numbers of positives and negatives, recombination will finally remove Fig. 2 2001", the conductivity of the gas. If there are unequal numbers of positives and negatives, the rate of recombination will depend upon The Way In Which Ions Diffuse to the Sides the relative numbers of each. If the ions of a Containing Vessel. Form of Tube Used for Measuring the Dis- removed field as fast as appearance of Ions by Recombination, with are from the they the Aid of a Quadrant Electrometer. are formed, that is by a saturation current, showing that the kinds of ions that are pro- recombination will not take place. If, how- duced, vary with the nature of the gas, ever. there is no electric field acting to re- highest powered microscope. Moreover it and with the temperature and pressure. move the ions, the number will increase Under certain conditions is too small to ever be visible to the human until they are so dose together that they the disappear- eye. That may seem like a rash statement ance of ions by diffusion is even greater in this day and age of scientific miracles, than by recombination, hence it must be and yet it must be remembered that the fleclroscope taken into very careful consideration. Dif- human eye is only sensitive to certain wave fusion is the thinning out or migration of lengths of light. Now the ion would either ions which may be due to the following reflect only a single pulse of light which J causes: If there is a greater density of 1IL ions in one part a would give it neither size nor shape, or it E of certain volume of gas would reflect waves of light many, many -1 than in another part, the ions will spread out times too short to affect the human eye. fig. 4 n toward the less dense part. If ions of one As long then as the human eye retains its sign only have been generated in a gas, any adjacent particles similar present limitations, the ion will remain in- Method Used In Determining How Fast Ions being of charge visible. Notwithstanding the fact that we Disappear By Diffusion By Means of An will repel each other and all of the ions will cannot see these we can prove Electroscope, Which Measures the Amount of tend to spread as far away from each other particles Charge In the Gas Passing Thru their presence by means of the electroscope the Tube. as possible. This is true of like ions when or electrometer, and we can obtain a meas- both positives and negatives are present. ure of the tots number present by measur- recombine as fast as they are formed or, Then when ions by any means approach ing the total effect on the instrument. Much in other words, the rates of recombination the wall of the containing vessel or any work of this kind, including the determina- and ionization are equal; then the gas will (Continued on page 279)

www.americanradiohistory.com August, 1918 ELECTRICAL EXPERIMENTER 241

FARMERS LEARN ELECTRICITY. HUNS HAVE DEVICE TO HELP ELECTRIC CHICK PICKER. The University of California is teaching U-BOAT CREWS TO SURFACE A machine invented by O. G. Rieske, of farmers to use electricity. In the near fu- AFTER WRECK. Buffalo, picks an ordinary fowl naked in ture the indications are that the efficiency Dutch newspapers describe a new method less than five minutes. Moreover, no of electricity on the farm will be generally by which crews of U -boats escape from feathers are scattered. A small electric recognized and adapted. PHOTOGRAPHING AUTO PARTS WITH MERCURY VAPOR LAMPS. A complete and accurate catalog of parts is one of the necessities for every automobile manufacturer. Every detail must be illustrated, either separately or assembled with others into one of the parts of the car. A unique method of taking the photographs necessary for these catalogs has been worked out by a prominent automobile manufacturer. Use is made of an elevated platform under which can be placed a large flat wooden table. On this are arranged various items, each with its appropriate title and number, printed on a card, laid beside or below it. The boundary of the photograph is marked by black wooden strips. Thru a hole in the platform the photographer focusses his camera upon the display below. Light is furnished by four mercury-vapor tubes, hung underneath and near the edges of the platform. Due to the highly actinic quality of the mercury -vapor light, the exposure is much shorter than with other illuminants DE AIL OF FEA ER Pl having the same apparent brilliancy. This arrangement possesses numerous ad- PERFORATED ROL R vantages, among which are that it enables the various parts to be associated with descriptive text, or explanations of the workings of complex apparatus. Much greater speed can be made in getting out RUBBER ROLLER instructions, since only one photograph need Anyone Can Plck Fowl at a Great Rate With This New Electric Feather Picker. It be taken of the entire group. Photograph- Picks an Ordinary Fowl in Less Than Flve Minutes, Without Scalding. ing from above is also very much quicker than from in front, because the parts can heir boats to the surface after they have motor turns a suction fan, and also a be much more easily arranged on the hori- been destroyed or wrecked. Statistics pre- roller contained within the instrument it- zontal platforms and removed or rear- pared by the German Admirality show that, self, the power being transmitted by means ranged for the next picture, than where it despite popular belief, a submarine runs of flexible cable. The roller is hollow and is necessary to tack up the parts on a ver- less danger in its operations than does the its outer surface is pierced by a number of tical background. -Courtesy 11"illys -Over- cruiser or other ship of war, and that de- slits which permit the incoming blast pro- land Co. spite the terrific strain, there has been a duced by the fan to pass freely thru it. very small loss of life among The top of the instrument is hooded and the crews. attached to this hood in a little rubber When the U -boat is wrecked roller which rests firmly against the sur- or disabled and lies on the bot- face of the large drum -like wheel. The tom of the sea a little compart- feathers of the fowl, sucked up against ment on top is opened and a the two rollers, are plucked by having to buoy which has been filled with squeeze between the rollers, after which air is released and at once rises they are blown to a tank. A thumb con- to the top, carrying attached to tact permits the hood to be moved around it a steel cable. Equipt with on its axis, and thus the relative positions "swimming vests," also inflated of the two rollers are adjusted according with air, the men climb to the to the needs of each case. The smallest surface by means of the cable. wild fowl or the biggest turkey may be During this climb to the sur- plucked with equal ease. A fowl can read- face each man wears over his ily be picked in the dry state, but ordinarily mouth and nose a small appa- it is scalded. ratus containing ,pure air, so that he is enabled to breathe oxygen. This apparatus at the EMISSIVE PROPERTIES OF same time purifies the carbonic acid, and keeps the air pure for TUNGSTEN. several hours. The buoy on The emissive properties of tungsten have the surface also is equipt with been investigated by two methods. One an electrical apparatus so that investigation consisted in the determination electric waves can be sent thru of the selective reflection of plane, highly the water calling for assistance. polished mirrors of tungsten in the visable The buoys are large enough to and in the infra -red spectrum. A depres- accommodate nearly all the sion was found at 0.8 in the reflectivity men of the crew. curve, which is the cause of a marked selec- When danger threatens the tive emission band found in incandescent alarm is at once sounded and tungsten. this new life saving apparatus The second investigation was on the se- is at once prepared for use, so lective emission of straight and helical fila- that the men can leave a U -boat ments of tungsten. in which it was shown within a few minutes. It is that the increased brightness within the said that this apparatus will helix is due almost entirely to multiple re- make the operation of the flection. The most important deduction is U -boats as safe as can be de- that the radiation from within the helix Photographing Automobile Parts With Mercury Vapor vised for their crews. Thus it is not sufficiently close to that of a uni- Lamps and Camera Set Vertically Above the Objects, Thus seems the Germans do find formly heated inclosure to be used in the Saving Much Time In Arranging the Display. time to invent safety devices. calibration of pyrometers.

www.americanradiohistory.com 242 ELECTRICAL EXPERIMENTER August, 1918

A NEW TELEGRAPHIC SIGNAL The motor is of the compensated series, NEW BATTERY SWITCH FITTED LAMP FOR MOTOR -BOATS. interpoled type, which will operate on WITH SPRING BINDING POSTS. In the accompanying illustration a tele- either direct or alternating current, so that A one point and two point wooden bat- graphic signal lamp is shown which is now a different machine is not required every tery switch which is equipt with the spring time you move. binding posts are now on the market. The The wick feed system of lubrication is handle of this switch is made in one piece used. and all the metal parts of it, including the NEW SELF -CONTAINED MICRO- binding posts, are fastened to the wooden PHONE BUTTON. handle by means of eyelets. This, it is If standard transmitters cost only a trifle, and were not much bigger than a thimble, every repair man could carry a few in his pocket. Then when a subscriber's instrument refused to talk for reasons unknown to the subscriber, and the repair man's ten mile trip disclosed a faulty transmitter, he could take a new one out of his pocket, screw it into place, and be on his way. A Chicago inventor, J. Skinderviken, has so nearly approximated this desirable condition that he leaves little to be desired in the way of transmitter repairs. He has One Point Battery Switch Provided With been allowed a patent on a self -contained Spring Binding Posts. transmitter button which meets practically all the conditions of our first problem. Externally the button is merely a cone- pointed out by the maker, eliminates all screws and does away with the loosening of any parts. The switch can be quickly wired on account of the convenient construction of the spring clip binding posts which are employed, without the use of any tools.

New Water -Proof Signal Lamp A NEW MILKING MACHINE. for Small Vessels. Easily Op- erated With Telegraph Key. This new electric milking machine profits by all the mistakes made by others, it is claimed. The new milking machine has no being offered by a Boston concern. Thi rubber milk tubes. It is suspended under the lamp as illustrated, consists of a 7 cow and can't be kicked off; nor can -inch by the 10 -inch brass anchor light with ' Fresnal' teat cups drop off and suck up dirt. It lens. For use with it in signaling, a special can milk a three- or two -teated cow as ly constructed Morse key is provided with easily as a four -teated one and can milk heavy platinum points, the base of which each teat independently. It has an ex- encloses a condenser connected across points clusive type- three -sided inflation that posi- of the key to prevent arcing and to shorten tively insures a three -sided collapse from the lag between make and break. An at- tip of teat to udder. It does not milk four tachment plug and cord is provided so that teats at once, but two at a time, alternately. the signal can be connected to any voltage The milk from each teat passes thru an electric circuit. It is very substantial and unbreakable, transparent, straight celluloid will stand ally weather. tube that is easily cleaned. You can see the milk flow, and as each quarter is milked A PORTABLE ELECTRIC AIR you can stop the action on it. These small COMPRESSOR. unbreakable tubes take the place of the long rubber hose, an essential part of most Here is a novel and efficient electric air milkers, and insure getting milk always as compressor that is really portable. It is clean and pure as it is in the cow's udder. built as a compact unit, with electric mo- It also has a float valve that absolutely pre- tor, high pressure compressor and trans- vents the milk being drawn back to the mission all enclosed in one frame. All one vacuum tank if the pail becomes full. has to do is plug in the nearest lamp And it can be operated by an electric mo- socket, either direct or alternating current, tor and in conjunction with any lighting connect the hose to your tire and turn on plant. the switch. The teat cups are radically new in de- The particular features in the construc- sign and exert a compound action; first it tion of this portable compressor are that Assembly and Exploded View of Remarkable sucks milk from the teat by vacuum and it is an New Transmitter Button. It "Talks" in Any built as integral unit, self -contained Position and Requires no Rear Bridge Sup- then shuts it off completely by atmospheric port. release, exactly duplicating the natural hand method. -Photo courtesy Western Electric shaped bit of brass with a threaded stem, Co. a nut and a lock -nut to fit the hole in the standard transmitter diafram. It has at least one paramount advantage over the regular transmitter. It talks equally well in all positions -vertical, horizontal, inverted, or at any angle. The method of repair used with this unique microphone button is to remove with a small screw -driver the metal bridge common to all standard transmitters. This bridge the repair man puts in his pocket, to be referred later to the scrap heap. The button then is screwed directly to the transmitter diafram, without any support but its own screw For Autoists -A Portable Elec- stem. The whole affair can be executed tric Air Compressor. in little more than a minute. This universal position feature makes the Skinderviken button very 'n a metal housing; its efficiency is increased useful also in repairing hand- micro- by means of forced air draft ventilation, phones, which are commonly sub- operated automatically, keeping the motor jected to the most severe distortions and cylinders cool at all times. There is no of position. The same is true to a Note How Surcingle Holds Pall of This New Electric water to freeze or to evaporate. lesser extent of the desk stand. Milker Firmly in Place.

www.americanradiohistory.com August, I 9 I 8 ELECTRICAL EXPERIMENTER 243 Experimental Physics By JOHN J. FURIA, A. B., M. A., (Columbia University)

Lesson 14- Current Electricity ing the terminals carries an electric cur- of electricity to pass thru it. Hence no Nelectrical charge in motion is called rent. (This was Oersted's experiment). electricity is lost and the pressure remains an electric current. EXPERIMENT That the terminals of the cell are electric- "full up" and is all measured. 80. -When a Leyden jar is dis- ally charged before they are connected, can EXPERIMENT 83 -Allow the current from be shown use of several cells to pass (a) ten feet A charged, we get a momentary cur- by of the electroscope thru of rent. If this momentary current is Lesson 13. On testing for the sign of the allowed to pass thru a coil of insulated charge we find the copper + and the zinc -. See Fig. 73. EXPERIMENT 82 -Allow the current from a voltaic cell to pass thru a vertical wire (see Fig. 74) and sift small iron filings around the wire. We find that the magnetic field consists of concentric circles lying in a horizontal plane. On exploring with a small compass we get results as in Fig. 74. On reversing the current the compass reverses. The direction of the magnetic field (the direction in which the N pole of a compass points) is related to the direction of the current by the right hand rule which is stated as follows: "Grasp the wire in which current is flowing by the right hand so that the thumb points in the direction in which the current is flowing; then the magnetic lines encircle the wire in The Voltaic Cell -It Produces an Electric the same direction as do the fingers of the Current by the Chemical Action of Dilute hand." instead of passing the current A Practical Experiment Showing How the Sulfuric Acid on Zinc and Copper. If Current in a Conductor Sets Up Magnetic thru a single vertical wire we allow it to Whirls in Iron Filings; Also, Reversing the Current Reverses the Direction of the Whirls copper wire which surrounds a knitting As a Compass Needle Demonstrates. needle, we find that the needle has become magnetized. (See Lesson 11 for test of number 30 copper wire, (b) 20 feet of magnetism.) It is to note important that number 30 copper wire, (c) 20 feet of num- electricity in motion produces a magnetic ber 20 copper wire and (d) 20 feet of num- effect, much since so of the value of elec- her 30 German silver wire respectively, and tricity depends upon this effect. (This ef- at the same time thru the fect galvanometer of was discovered by Prof. Flans Chris- Fig. 75. We find less passes tian that current Oersted of the University of Copen- thru the smaller diameter copper wire than hagen 1819. in His experiment, known as thru the other. Also less current passes Oersted's Experiment, marked the begin- thru the German silver than the cop- ning modern thru of electricity. per; again, less current passes thru the 20 EXPERIMENT 81 a -Only small amount of feet of copper wire than thru the 10 feet. electricity passes thru the wire in experi- Hence we say that German silver offers ment because 80 the current lasts for so more resistance to the passage of elec- small a a fraction of second. Galvani in tricity than does copper. Also the longer 1786 discovered a chemical method for pro- the wire the more the resistance, and finally ducing a continuous current and Volta in the smaller the diameter of the wire the 1800 invented the voltaic cell (sometimes greater the resistance. called galvanic cell). He a placed strip of Comparing the wire to a pipe is zinc water it and a strip of copper in dilute sulfuric obvious that the smaller the diameter of acid (see figure Various Actions of Magnetic Fields. The Gal- 73). If the terminals of the wire or pipe the less the electricity or this cell are connected to the coil surround- vanometer Works Upon the Principle Tha A Magnetic Needle (b) in a Coll, or a Current - water passing thru and hence the more the ing the needle knitting for several seconds, Carrying Coil in a Magnetic Field (c) will resistance. (The unit of resistance is called we find the needle more Tend to Move. strongly magne- the Ohio and is equal to the resistance of tized than in experiment 80. Hold the wire pass thru bent as 75 9.35 feet of number 30 copper wire). connecting the terminals of the cell over a a wire in Fig. (a) we have a stronger (Continued on page 279) compass needle; the compass needle will still magnetic field and if be strongly deflected, i.e., the wire connect- we use a coil as in Fig. 75 (b) the strength is increased still more, since each turn adds to it. Using more current also adds to the strength of the field. A compass needle placed in the center of the coil 75 (b) will be deflected and the greater the current the greater the deflection. All instruments for measuring current consist essentially either of a compass needle at the center of a fixt coil as in Fig. 75 (b) or of a moving coil suspended between the poles of a fixt magnet as in Fig. 75 (c). The passing of the current thru the coil produces a deflection as in Fig. 75 (b) of the needle and in Fig. 75 (c) of the coil. Such an instrument is known as a gal-. vanometer. When calibrated to give the strength of current directly it is called an ammeter. The ammeter has low resistance so as to oppose the passage of electricity thru it practically not at all. Because of the practically nil obstruction, all the current passes thru it and therefore we get a A fig. 77 true measure of it. The voltmeter or instrument measuring How Battery Cells Are Joined in Series (A) Various Problems in Ohm's Law. Simple for electrical pressure, is to for High Voltage and in Parallel (B) for Resistance At A; B- Resistances In Serles, similar the ammeter but has a high re- High Current. For High External Resistance C- Resistances in Parallel. sistance. This allows only a small amount Use a High E.M.F. and Vice Versa.

www.americanradiohistory.com 244 ELECTRICAL EXPERIMENTER August, 1918

Notice to All Radio Readers . As most of our radio readers ore undoubtedly aware, the U. S. Government has decided that all Amateur Wireless Sta- tions, whether licensed or unlicensed, or equipt for receiving or transmitting, shall be closed. This is a very important consideration, especially to those who are readers of the ELECTRICAL EXPERIMENTER, for the reason that we desire to continue to publish valuable articles on the wireless art from time to time, and which may treat on both transmitting and receiving apparatus. In the first place, there are a great many students among our readers who will demand and expect a continuation of the usual class of Radio subjects, which we have published in the past four years, and secondly, there will be hundreds and even thousands of new radio pupils in the various naval and civilian schools thruout the country who will he benefited by up -to -date wireless articles treating on both the transmitting as well as receiving equipment. Remember that you anut not connect up radio apparatus to any form of antenna. -The Editors.

John Bottomley, Director, Marconi Co., Dies

CO M M E R C I A L wireless lost a Harlem Library, now incorporated with the of engineering and in charge of the electri- pioneer from its ranks when John Public Library, vice -president of the Har- cal laboratory. During 1914 and 1915 he was Bottomley, third vice- president, sec- lem Dispensary and trustee of the Empire in charge of the army radio construction retary and treasurer of the Marconi City Savings Bank. work in the Philippine Islands, and from Wireless Telegraph Company of He was born in Belfast, Ireland, in 1848, October, 1916, to October, 1917, he was on America, died in the Post Graduate Hos- where he received his early education. later duty at the Fort Leavenworth Army Signal pital, New York, on Sunday, June 16th. entering Queen's College. At the age of School, acting as its director from October, Mr. Bottomley was in his seventy -first year. twenty-two he was placed in charge of a 1916, to May, 1917. large exporting house, where he remained He was promoted to captain of the Signal for ten years, coming to America in 1880. Corps in September, 1916, and to major in Here he studied law and was admitted to August, 1917. Since October, 1917, he has the Bar, being engaged in this profession up been on duty in the office of the chief signal to the time when wireless claimed him. officer of the army. Major Mauborgne has Mr. Bottomley was a nephew of Lord had ten years of experimental work in Kelvin, the noted electrician, and a grand- radio -telegraphy and is the author of "Prac- son of James Thomson. A brother, James tical Uses of the Wave Meter in Wireless T. Bottomley, is a scientist in Scotland. He Telegraphy, 1914," and articles on radio is survived by his wife, two sons and two research in the technical press of both daughters. America and Europe. He is also a member of the Institute of Radio Engineers, and a BRITISH GIRLS STUDY RADIO. member of the advisory board of the invention section, War Plans Division, Gen- English girls are taking up wireless eral Staff, U. S. A. telegraphy in earnest. The Marconi company has started a special school for training women in wireless telegraphy at its North Wales Station. The course deals with slip reading, punching, record reading and the general duties of a wireless station. The girls will be drafted to land stations when efficient and will go on night duty in rotation. It is not proposed to extend the use of r women to ships for the present, but if this is to be altered it probably will apply only to coastwise shipping. The Late John Bottomley, Third Vice- Presi- dent. Secretary and Treasurer of the Mar- MAJOR J. O. MAUBORGNE, SIGNAL coni Wireless Telegraph Company of Amer- ica. He Introduced the Marconi System to CORPS, U. S. A. the American Business World. Wireless men everywhere will remember the useful and timely hand-book on the Twenty years of ceaseless activity in the Wavemeter, written by former Lieutenant radio field are credited to the deceased, for J. O. Mauborgne, U. S. A., now Major it was in 1898 that he first met Marconi and Mauborgne, and who has been in charge of took up the responsible task of introducing the electrical engineering section of the wireless telegraphy to the American world Signal Corps since March, 1918. He was of commerce. In-1902, he became the active born in 1881 in New York City. He was head of the American Marconi Company. graduated in 1901 from the College of St. At the time of his death he was vice- presi- Francis Xavier and recommended to the dent and a director of the associated Mar- War Department as standing highest in the coni Telegraph -Cable Companies, treasurer military department upon graduation. Two of the Pan- American Wireless Telegraph years later he was commissioned second and Telephone Company, treasurer and di- lieutenant in the regular army, and he was rector of the Wireless Press and treasurer promoted to first lieutenant in April, 1909. Major J. O. Mauborgne, in Charge of the of the Marconi Institute. Mr. Bottomley He was graduated in 1910 from the Army Electrical Engineering Section of the Signal Corps, Is One of the Best Known Radio Ex- had been president of the New York Elec- Signal School at Fort Leavenworth, Kan., perts in This Country. Wireless Men Every. trical Society and was an active member of and for the next three years was instructor where Find His Timely and Eminently Use- the Engineers Club, vice -president of the there in radio telegraphy and other branches ful Book on the Wavemeter Invaluable.

www.americanradiohistory.com August, 1918 ELECTRICAL EXPERIMENTER 245

MEMORIZING THE CODE. BOYS' WIRELESS SEIZED; NAVY Amateur Radio Men, that you are being I read with interest "A Short -cut to Code GETS TWO RECRUITS. watched closely all the time by those (* Learning" in the January number by Zzz -szx) ! - * * ?: sszzxz- sz-splutter ! whom you least suspect. Therefore strive Thomas Reed. I will try to describe a "German spies," gasped a neighbor as he to hold your head high; if you are am- method used by the Swiss Boy Scouts that heard the hissing noise and watched the bitious and can't hold your radio aspira- has proved very successful, and, in fact, sparks flashing from the home of Mrs. Pat- tions any longer, then go and enlist at so successful that it is the only way they know the code. Each letter of the code is represented by a word that begins with the same letter, so as to simplify recognition. Also each "dot" or "dash" of the code is represented by a r.,.y i KW Sr. syllable (of the word). And, last, every r.w..r+ JA..nryr D.mr.v . p... ._.. syllable containing the vowel "o" means a .. . ._._ I Ii dash in the code. /r....-. . A few examples will make the process clear. Take for instance -B = - ... = Bonaparte. Bonaparte contains four syllables; the first syllable contains the vowel "o" which means that the letter in the code begins with a dash; the other syllables do not contain "o" and therefore are dots. Thus: 111 G = Gondole = - - . 4i%' A = Arnold = . - H = Hilarité = . . . . F = Farandole = . . - . S = Sardine = . . M = Moto = - - E =Eh! = . I will not give the equivalents for all the alphabet, as all these words are unfortu- ':Në.i Ç::...... o a .-. nately in French and would be of no use, but it would be easy with enough time to make one up in English. However, I do not think learning the code by these methods are efficient, as they only help to make the code more easy to the and later he will have mem- How to Teach Hookups to Radio Men? That Was the Problem. A Canadian Instructor beginner to Finally Evolved This Ground Glass Slate, Under Which the Various Apparatus Are Placed. orize it, the usual way. The Student Must Draw the Circuit Lines in with a Pencil. II. SIMPLIFYING RECEIVING I think that simplifying receiving would rick O'Shaugnessy, at New Canaan, Conn. once. Your Uncle Sam needs you!!! be of some help to the beginners and the Again came the hiss and the spark. The method I will now describe is very useful. neighbor jumped to the telephone and the NEW "GLASS SLATE" FOR TEACH- This method is also used in Switzerland by next day Federal raiders swooped down on ING HOOK -UPS. the Boy Scouts. (I do not know if it is used the O'Shaugnessy cottage. Mrs. O'Shaug- Patents have recently been applied for in elsewhere.) And I think not only helping nessy sobbed a plea that her only boys, Wil- various countries on a drawing slate in- beginners in wireless, but it would be of liam, twenty, and Thomas Francis, eigh- vented by a Canadian Wireless Instructor service for heliograph receivers. teen, be forgiven this time. But the raiders to meet the difficulty of teaching students This method requires a chart containing frowned. It was against the law for ama- to memorize and understand the connec- the alphabet and numerals (see illustra- teurs to fool with wireless apparatus in tions of various pieces of apparatus as re- tion). The letters are divided into two war time. "Shucks," laughed Tommie, "we quired by Government examiners. groups -those beginning by a "dot" and were just studying so we could get in the The wireless student who has learned to those beginning by a "dash.' navy wireless branch." draw the connections of apparatus arranged Also a straight line ( ) represents The Federal officials learned the state- always according to a particular plan, in- a "dash" and a dotted line a "dot" (. .). ment was true, but had to confiscate the ma- variably encounters trouble when presented Thus when a letter begins with a "dot" look chine. They suggested in leaving that the with a diagram representing the same pieces at group I and if with a dash at group II. boys could get practical wireless experience of apparatus placed in entirely different Take for instance letter A ( -) without interference by joining the navy. positions with respect to each other, and it (1) Look at group I. (2) As the next "That's what we will do," agreed the boys. is only then that he realizes he has wasted symbol is a "dash," follow the straight line And they did. Mrs. O'Shaugnessy pre- considerable time in merely accustoming and we come to A. sented herself to Chief Yeowoman Mrs. himself to repeatedly drawing the same con- Now take the letter Z ( .. ). George Wheelock at the Naval Recruiting necting lines in the same order, without (1) Look at group II. (2) Follow the headquarters. She had Tom in tow. She grasping their meaning. straight line. (3) Follow the dotted line. explained she had tried to keep the boy at The present invention, a direct product (4) Follow the dotted line. Thus to find home, but had to yield. of necessity, takes the form of a framed the letter we pass thru T, M, G, and Z. Tom was found to be 100 per cent physi- sheet of ground glass, beneath which repre- sentations of the various parts comprising a wireless or other electrical equipment, printed in heavy black lines upon blocks of Beaver Board, are arranged, and upon the Group J Group." ground upper surface of which the proper connections are to be drawn in pencil with ;Vo/ used i» the aid of a ruler or set square. The Amer/co blocks are tightly clamped between the glossy under side of the glass and a wooden back to which the frame is hinged, so that the slate may be past round among several students, each of whom will draw in the connections and afterwards erase the pencil lines with water, or preferably a few do/ `/ No /after drops of gasoline applied with a sponge or -dash ,ordilob,/e No letter groï/abled piece of rag. When required, the blocks fx - To.fihd 1 we /Am tiro 'E,r+.R.[. may be re- arranged or replaced with rep- resentations of parts comprising some other standard equipment. The blocks are very Simplified Code Chart for Quickly Memorizing the Mysterious Dots and Dashes, as Described inexpensive and can be supplied in sets by Mr. Bauman. To Find " Z," for Instance: Look at Group II, Pass Thru T, M, G, and Z; Thus "Z" Is Dash, Dash, Dot, Dot. making up complete wireless installations. Essential details of standard receivers This, I think, is the easiest method to cally fit and easily past the wireless tests. of all types, automatic starting devices, decipher a code and by looking at the dia- We regret to hear of these indiscreet motor generators, etc., can also be printed gram it is readily understood. Hoping this ventures of American "Radio- bugs," for on the blocks enabling students to under- will interest some amateurs. they should set a perfect example in stand the relation of each part to the other. Contributed by their respective localities of just what a Blocks representing Chemistry Apparatus HAROLD A. BAUMAN. "good" American citizen is! Remember, can also be supplied. www.americanradiohistory.com 246 ELECTRICAL EXPERIMENTER August, 1918 AN IMPROVED CONDENSER HOW TO USE SHORT INTER- VICTROLA NOW TEACHES SCALE. RUPTER RODS. WIRELESS. The drawing shows a special graduated Procure a miniature coupling from an One of the largest talking machine com- scale which, when substituted for the con- Erector building outfit, take an alloy rod panies has just announced a special course denser scale, will show the exact position of that has become too short for ordinary of instruction in wireless telegraphy by means of disc records and accompanying books of instruction. In announcing the course the company says in part: "The United States Army and Navy are in need of thousands of skilled wireless 'Pointer operators, and a complete course of study may be carried on by means of these records, in camp and at home, at a very small fraction of the expense that is ordinarily involved. "The course consists of six ten -inch double -faced records with book of instructions." A SOMEWHAT DIFFERENT ROTARY SWITCH. Many amateurs are building receiving sets with a receiving transformer using rotary switches for regulating the number of turns of wire in use. These switch knobs and as- io semblies are quite expensive when bought, but can be easily and cheaply constructed at Tops on secondary Taps. 00 secondory, home without machine tools of any kind. The material needed will be a piece of one - vuriubik -cond. fourth inch rubber or fiber sheet, a brass knob , battery bolt with the nuts, a binding post as shown in the dotted line in the drawing, 4 and some spring brass for the lever of the switch. Determine the size of knob you By Making a Special Scale for the Variable Condenser of a Radio Receiving Set, It wish, lay out the circle of the proper diame- Becomes a Simple Matter to instantly Set the Condenser to Correspond With a Certain ter on the fiber or rubber, and then cut out Tap for a Given Call. the disk. A heavy gasket cutter will help do this if the knob is made of fiber. If the condenser for each number of taps of use, put this thru the hole in the cover, hard rubber is used, it can be cut out by the secondary. As you will notice by the take off the tube from the interrupter, and chipping off pieces with pliers till a rough drawing, as the turns of the secondary are place the coupling in the tube with a piece disk is secured. Then this is filed down till increased the condenser is brought nearer of straight copper wire A in one end, and perfectly round. zero, and in the case of NAA the more taps alloy rod C in the other. Replace tube and Drill a hole in the center and in this place are taken off the greater the condenser a long battery binding post, whose flat end capacity used. This, of course, is naturally has been filed smooth and polished. Fasten necessary, but the idea of the arrangement it with a nut that has been rounded, to is to show when for instance four taps match the round handle. Then cut a piece are used the condenser scale will be at an of spring brass to the desired shape, mak- indicated point. By this method, after noting it narrow at the outer end. Punch a ing on the scale where different stations hole at the wide end and fasten it on the come in, it will be an easy matter to tune bolt in the knob by means of another nut. in these same stations again when desired. Next drill a hole in the board or panel I have been using this method to great on which the switch is to be mounted. This advantage, especially when time is the prime hole should be large enough to admit the factor, that is when one wishes to listen binding post shown in the sketch, but not so for two or even three stations at once, by large that it will let the collar or wide part merely changing the secondary taps and slip thru. A binding post of this kind can a lot of unnecessary time formerly lost by be found in practically every experimenter's moving the condenser to the exact point shop. It is threaded at both ends to fit a and having to hunt for each one is saved. battery bolt. Push the small end of this Contributed by T. T. J., U.S.N.R.F. binding post in this hole, then from the rear insert a binding post on which a washer and a nut have been placed. Draw up the bind- UNIVERSITY OF PITTSBURGH ing post into the hole by means of the nut By Means of a Small Wire Connector It Be- at the back. Then screw the knob screw GIVES RADIO ENGINEER- comes Possible to Use Up Short Bits of into the hole in the Electrolytic Interrupter Rods In the Manner binding post at the front ING COURSE. Illustrated. far enough so that it will not have any play A course in Radio Engineering for tech- and so that the blade makes good electrical nical graduates is being given at the Uni- contact with the switch points. If a little the interrupter is ready for use. This is a judgment is used in designing the layout of versity of Pittsburgh which comprises a very economical way of using these alloy term lasting eight weeks. This course will the switch and contacts, it will look better rods as they can be used to the last inch. than many high priced switches, and will be be open only to graduates in electrical or Contributed by JOHN ROGERS. mechanical engineering who are recorded in just as serviceable. Class I of the National Army Draft. Men Contributed by FRANK SAHLMANN. enrolling in it will be placed by the Gov- '9111MIIIiMü IT11111111111101llllll10111131I1I0I 1111III11111111!IMI ernment in Class V until completion of RADIO WRITERS - ATTENTION I i I the course, when they will be inducted into Can you write radio articles dealing the Signal Corps and sent to an army school with the practical problems of wireless for further training. The need operating? We can use some good for men papers on such subjects as "the tuning familiar with the technique of radio-com- of radio transmitters "; "the use of the munication is great, and the chances for wave meter, including its application obtaining a commission ultimately are good. to measuring the frequency, wave length and decrement "; "operation of There will be no charge for tuition, but commercial transmitting and receiving students must provide their own living and sets "; "the operation of army trunk travel expenses. E sets "; "improved ways of receiving undamped wave signals," also new As the number of men is limited, appli- Ideas and short -cuts for learning the cation should be made at once to Prof. H: t--= codes, We pay well for all articles I= M accepted. Help yourself, your maga- j= E. Dyche, Department of Electrical Engi- tine and your A New Wrinkle In Building Rotary Switches. neering, University of Pittsburgh, Pitts- country. The Switch Points Comprise Short Pieces of Brass Rod Forced Into Holes of Slightly burgh, Pa. fMIMM ECEIIM0RMMMMIMMMEMIUIlIl1IIIIMIIMVi Smaller Diameter Than the Rod.

www.americanradiohistory.com August. 1918 ELECTRICAL EXPERIMENTER 247 Analysis of Irregular Wave Shaped Alternating Curves Harmonics -Part II

By Prof. F. E. AUSTIN * . Instructor of Electrical Engineering, Thayer School of Civil Engineering, Dartmouth College CCORDING to the discovery of sum of the sine curve heights extending other indicating device, or which combine Fourier, any periodic or regularly re- above the datum line. If the sum of the to form the current waves which may be curring wave of any shape whatever, downward or negative heights exceeds the recorded by employing the oscillograph, a is in reality the resultant obtained sum of the upward or positive heights, then few of the simpler laws governing the by adding together a number, (usu- the point of the resultant curve is located forming of wave shapes will be considered. ally a large number, sometimes an infinite below the datum line. It may happen that If a curve having any irregular shape, the sum of two negative heights may have to be subtracted from a single positive height. Any irregular but periodic curve of current or pressure, meaning one that repeats the same irregular shape during each succeeding interval of time, may be exactly reproduced on paper by the proper selection of sine curves. Fig. 2 shows an alternating curve made up of four simple I`I//A\ LAM,I/SALA /A sine curves. The building up of such Yig \te AVOW \11y `I irregular periodic resultant curves is called synthesis. Of course it is not possible to build up curves of any particular shape J until it is definitely known exactly how many sine curves are necessary; their frequency, their amplitudes, and their start- The Heavy Line Represents the "Resultant' ing points relative to each other. The de- Curve Made up of Four Simple Sine Curves termination of the number, frequency, am- he Latter Are Known as the Harmonic Com One Practical Method of Exploring the Pre- ponants and Each Has a Definite Frequency plitudes, and position of the component dominating Harmonics Constituting a Resul and Wave Length. sine curves making up any resultant curve tant Wave Current Is by Means of the Fre quency Meter. Each Reed Responds to a is called analysis; which is a somewhat Definite Frequency. number) of sine waves, one of which has complex operation; depending upon cer- the same frequency or same periodic time tain known mathematical relation and which exactly repeats itself during each as the original or resultant curve. physical laws. regularly recurring interval, has its, two Any alternating current or pressure of It may be well to consider for a moment half -waves exactly similar, (one -half being any shape whatsoever according to entirely above the horizontal datum Fourier's theory, is made up of the , r and the other half being entirely be- sum of a definite number of simple qF r ' I . i e s' W 4' low the same horizontal datum) both sine ,1_ waves of current or pressure, li 991Ì ,i ' 4 dikt as regards their shape and their posi- ii4 l law having various amplitudes 3 and differ- p d tion, then the curve is made up of ent wave lengths or frequencies. u_ 4 , .ü ; sine wave components whose fre- Many surprising results may be quencies or periodic times are odd obtained by simply arranging sine multiples of the original or the re- curves on cross section paper, and :I,. sultant curve. -t , adding algebraically their heights at a j-9- This important feature, which may '4 o-lw various points and drawing a curve M --I, % always be ascertained by inspection, thru the points so located. This may =^.s1+.. renders it possible to eliminate from be illustrated by Fig. 1, in which three any system of wave shape analysis, sine curves are arranged as indicated, Fig. 1, Showing How the Three Sine Wave Components, all component sine waves whose fre- and their altitudes added together Whe n Added Together, Produce a Certain Form of "Re- quencies sulta nt" Curve. The "Resultant" Varies in Shape as the are even multiples of the algebraically forming the resultant Harmonics or Components Composing It Vary; resultant curve. curve, drawn in heavy lines. It may This feature is illustrated by Figs. be noted that if at any chosen position two why an alternating current or an alternating 3 and 4. Fig. 3 shows an alternating current or more sine curve heights are positive, pressure does not have a perfectly simple wave, or periodic curve in wide line, which that is extend above the horizontal datum form. The alternating pressure obtained is the curve resulting from the sum of the line, then the sum of the sine curve heights from a generator depends at each instant (Continued on page 281) extending downward below the horizontal of time upon the speed of the moving in- datum line must be subtracted from the ductor and upon the strength of the mag- Copyright by the author. netic field thru which the inductor is moving. If for example the motion of the inductor should be perfectly uniform, but the field should be variable, then the induced pressure would vary accordingly; on the other hand should the magnetic field be perfectly uniform, but the motion of the inductor be variable then the resulting induced pressure would be irregular to con- form. Again both of the variable conditions might act simultaneously, either in unison to increase the induced pressure or in opposition to reduce it. There may also be other causes of pressure and current distortion resulting from apparatus connected into the generator circuit; such as condensers, motors, telephones, and coils of all kinds. As it is often desirable and necessary to obtain the number and maximum values of the component sine waves or harmonics, which combine together to form alternating pressure Fig. 5 Shows the Component Waves of Fig. S Fig. 4 Shows the Change in waves, whose shapes may be ob- the "Resultant' in Still Further Displaced -Note the "Resultant. ' Curve Produced by the Harmonic Compon tained practice by the point by point Fig. 6-Effect of Simply Changing the Maxi- ents of Fig. 3 Being Slightly Displaced. method, employing a telephone receiver or mum Vague of Only One of the Components.

www.americanradiohistory.com 248 ELECTRICAL EXPERIMENTER August, 1918 The Design and Use of the Wave -Meter PART IV By MORTON W. STERNS

calibrating a decremeter a source of However, the hot -wire type is the most point is the point at which the hot -wire undamped oscillations is used and the generally used because of its lower in- instrument gives the maximum deflection usual formulae for decrement are em- ternal resistance, which is a very important or the point at which the loudest signal is INployed which make use of the decre- consideration in the design of the decre- heard in the head telephones, if a crystal ments of the coupled circuits & + 3.; meter. detector and telephones are used. By not- however in this case the decrement of the A very popular type of instrument on the ing this resonance point in degrees and re- market at present is made by an American concern, and is called a hot -wire wattmeter. Its scale is divided into one hundred divi- tYovemetert sions according to the square of the current flowing thru it. Its resistance is 6 ohms and it requires 80 milli- amperes for full scale deflection (.0384 watt). In case only a direct reading milli -ammeter is available, if we make P = %Pm- if P. is equal to 100, then I' must be equal 1

to 70.7 or 1 90' 180` 2 Crab/ bee Fi ,1 In part I of this series the author has fi.5 meosurcmea listed the Characteristic Decrement Curve of a Dec - various measurements that can remeter Coil Showing How the Meter Decre Where Many Measurements Are to Be Made ment Varies With the Capacity. It Is Well to Have An Oscillating Audlon Circuit Hooked Up As Indicated to Act As An Exciter for the Circuits Under Measure- source is zero (undamped waves), and the ment. measurements calculated are the meter dec- Detector rements. ferring to the wave -length curves furnished This meter decrement varies with the with the meter, the emitted wave -length can be readily found. capacity and is kept below .05 if possible. lqr11 A characteristic decrement curve of a dec- Figure 2 illustrates the method used in measuring wave -lengths and is remeter coil is shown in the accompanying Phones transmitted figure 1. familiar to all. Wave meter coils generally overlap 20% Figure 3 shows the wave -meter excited in wave length, the idea being to allow a Mot wire Instrument by a buzzer and coupled to the antenna thru check of certain waves on two coils: this a single turn. 2 also shows if the calibration of the meter EE If the receiver is tuned to the incoming has changed or not. signal and the coupling between the wave - In the new Marconi type No. 28 wave Method of Using Wave -Meter in Determin meter and the single turn in the antenna meter there is a correcting wave -meter con- ing Transmitted Wave- Lengths, Utilizing lead made small, the buzzer signal will be Either a Hot Wire Meter or Detector and sisting of fixt inductances and capacities 'Phones. superimposed on the incoming signals and which may be excited by means of a buzzer, will be weak enough so as not to interfere and picked up on the main wavemeter. with the reception of messages. By this means it can be seen if the calibra- be made with a wave -meter and as can be The point on the wave -meter that gives tion has changed; and if so it can be cor- readily seen it includes practically all the the loudest signal in the receivers is then rected by adding or subtracting capacity the wave -length at which the incoming on a correcting condenser, which is per- message is being received. manently connected around the main con- An alternative method is to couple the denser. It is, of course, understood that Buzzer° wave-meter closely to the antenna circuit the main wave -meter was calibrated with and when a signal is tuned in on the re- this correcting condenser half in, thus al- s ceiver, the wave -meter is varied until the lowing an addition or subtraction of capac- signal dies out or becomes very weak, the ity to correct the calibration. The correct- minimum point being the wave -length of ing condenser had a capacity of one -tenth the received signal. of that of the main condenser. The reason the signal becomes weakened Now a word in regard to the hot -wire is due to the fact that the wave -meter ab- meter used in the decremeter of to -day. Novemefer sorbs most of the received energy at the As a rule a hot -wire type instrument is resonance point, due to its close coupling. used, on account of the high frequency A. C. that is to be measured, but a D.C. I!. Measurement of Decrement. milli -voltmeter shunted across a thermo- 3 In Part III of this series, the method of couple would also be satisfactory. Several measuring decrement with the Kolster dec- meters of the latter type with self- contained remeter was fully described. thereto- couples are on the market at Coupling the Wave -Meter Inductively to the present. Receiving Antenna in Order to Measure Wave -Length of Received Signal.

Navemefer important measurements used in Radio En- gineering to -day. We will now take up the sm various measurements in order. fig. 6

Known MEASUREMENT OF TRANSMITTED OR -f mpocity RECEIVED WAVE- LENGTHS od to be 45' 50' 55° The wave -length of a transmitter can be Condenser degrees ;n-osured measured by bringing the inductance coil I EE in proximity to the antenna lead of the transmitter and varying the condenser over In Making Measurements With the Oscil- lating Audion a Mean Value of the Con- Measuring the Inductance of a Coll With the scale with the various coils in circuit denser Readings is Chosen, Varying Be- the Wave - Meter. to give the required range. The resonance tween A and B.

www.americanradiohistory.com August, 1918 ELECTRICAL EXPERIMENTER 249

The usual method of measurement with If only a few measurements are to be The circuit L is brought near the Audion the ordinary decremeter or wave -meter may made, the simplest method is to connect the coil and the condensers C and C. varied ; bear repetition, as it is one of the most standard inductance in parallel with the resonance should be obtained at 50 °, but difficult and at the same time most useful condenser of known value and use a uni- due to the energy withdrawn, oscillations measurements in Radio Engineering. lateral connection for the detector and cease at 45° when increasing capacity and The coil of the decremeter is brought into 'phones. The unilateral connection is used at 55° when decreasing capacity in each so as to make the readings more accurate case, causing the characteristic "kiss," and and to eliminate the high resistance of the neither point being the true resonance detector and 'phones around the condenser. point. If now the coupling between the two Fig. 4 explains the method: The wave - circuits is diminished, A and C will ap- meter duly excited by a buzzer is brought proach B as a limit and soon the adjust- into inductive relation with the coil un- ment will be so sharp that the two points der measurement. As the condenser in the A and C will be less than one degree apart wave -meter is varied the sound of the buz- on the small condenser, and the mean of zer will be heard at a sharply defined reso- the two readings will determine B quite nance point in the telephones. Then noting accurately. It is to be noticed that the the wave -length shown on the wave -meter values of inductance and capacity in the and knowing the capacity in circuit B we Audion circuit need not be known. IV. Making Resonance Curves One Method of Exciting a Wave -Meter With substitute in X =59.6 L C, and find L a Buzzer. The Current for the Buzzer Passes a' The whole procedure of plotting a reso- Around Thru the Inductance Coll. directly by the formula, L - nance curve was explained in Part II, and 3550 C should be referred to by the reader, as this inductive relation with the circuit under X If many measurements are to be made, is a rather important measurement to be measurement and the condenser is varied made. until the resonance point is found as shown it is best to have a permanent set -up in by the maximum deflection on the indicat- place around the laboratory, so that one V. Making Various Antenna Measurements ing instrument. The coupling between the can go right to the corner and make measurements in a few minutes. The author To measure the effective capacity of the decremeter and the circuit under measure- antenna find the natural period of the an- ment is then increased until large deflec- has a circuit like the one described in constant use and has saved much time thereby. tenna by exciting it with an induction coil tions of the indicating instrument are ob- connected across a spark gap, one side of tained, care being taken that the meter is It is a very compact arrangement and has a range of 50- 30,000 meters. which is grounded and the other side of not burned out at the resonance point. which is connected to the antenna. A coil Now if we are using a direct reading Coil A is a long bank -wound coil tapt at consisting of a turn or two of wire of negli- the various points to give continuous wave- gible inductance is milli- ammeter of thermo -couple type, length connected in series with the maximum current at the resonance ranges with the two condensers C the antenna in order to allow the wave - point is noted and also the capacity of the and C,, see Fig. 5. The points B and C are meter to be coupled to the antenna. condenser. Then the capacity is decreased made as clips to clip on the coil for the When the induction coil is energized a until the current reads 70.7% of its former various ranges, the point B always being spark will jump the gap and the antenna value and the capacity again noted. We about half -way between A and C. will oscillate at its natural period, which we m. f. then have sufficient data to substitute in C is a .005 condenser connected in will designate as X,. A known capacity, C,, Bjerkness formula and calculate the decre- is then inserted in the ground lead and the ment. From this value of decrement sub- wave -length X,, obviously smaller than X,, is tract the instrument decrement at the reso- measured. nance point and the decrement of the X,' emitted oscillation is directly obtained. Then C = C, The reason the current was decreased to X,' 70.7% of maximum value is as follows: where C = the effective capacity of the In order to make the current radical, antenna in microfarads. Care must be sÍ+ P taken that C. is chosen of such a value that I X. does not vary more than 20% from X,, Arrangement for Measuring the Mutual In- as the effective capacity of the antenna ductance Between Two Coils, Such as the varies somewhat with the wave -length. equal to unity, P must equal %L'. If we Windings of a Variometer wlth'the Ald of a Knowing the natural period of the an- 1 Wave- Meter. tenna and its effective capacity, then its in- consider L'= 1, then P= % and I = -= parallel with a smaller condenser having ductance can be simply calculated. Another V2 about .0005 m. f. method would be to place a known induct- .707. Therefore, I must equal 70.7% of L. The circuit L under measurement and ance in series with the antenna and meas- Of course, if a current squared meter is uring the wave -length X,, then knowing the used we take any reading at resonance and containing a known capacity is brought into inductive relation with the coil of the natural period of the antenna X,, we find decrease to % reading on scale, then I'= the inductance of the antenna from: because readings are proportional to oscillating Audion circuit and the condenser the square of the current I'. C varied until resonance is obtained. Reso- nance can be determined by hearing a L= sharply defined point that gives a "kissing" III. Measurement of Inductance and sound in the 'phones of the Audion circuit. Capacity The distance between the coils is varied L = Inductance of antenna in cms. until the "kissing" sound in the 'phones is L,= Inductance of standard in cms. Capacity and inductance can be quite moving the fine adjustment con- easily measured by means a wave heard on VI. An Exciter Emitting Waves of of -meter, denser C, one degree in either direction. Predetermined Length because knowing either the inductance or Then allowing the Audion circuit to re- the capacity in the circuit, the other can main adjusted, the wave -meter is brought Figure 7 shows how a buzzer is connected be found by substituting in the fundamental at the "kissing" to excite a wave -meter. By setting the equation: near and the point which sound is heard is noted. We then know X =59.6 LC the wave -length and the capacity and sub- L is found. where X = wave -length measured by wave - stituting in the usual formula, meter. This method is very rapid and accurate L = inductance in cms. and results can be checked very easily to a C = Capacity in microfarads. small fraction of a degree. The accuracy of the method is apparent as no attachment Thus it is shown that in order to measure of any sort is needed to be connected to inductances a standard of capacity is needed the wave -meter. and vice versa. I will describe the measure- The principle under which the method ment of inductance but the reader will operates is that when a resonant circuit is readily see that the same procedure is fol- brought near the "osculating" (pardon the Hook -Up of Radio Instruments for Measuring lowed in measuring capacity. the Natural Period or Wave- Length of a Coll. pun) Audion, energy is withdrawn from the The Coll Under Test is Connected Unilaterally The question now arises as to how to circuit at a faster rate than the B- battery to the Detector and 'Phones. make the measurements simply and quickly can supply it, and the bulb stops oscillating, rather than to explain the theory. I will which gives the kissing sound in the 'phones. condenser at any value any predetermined therefore explain a simple method I have The accompanying diagrams shows the wave can be emitted. The theory is that used and which will save many hours of only point to be looked out for in this pro- the inductive kick due to the breaking of time. cedure. (Continued on page 284)

www.americanradiohistory.com 250 ELECTRICAL EXPERIMENTER August, 1918

How to Make a Simple Spectroscope By DONALD S. BINNINGTON

IT is a well -known fact that when white Fig. 3, which shows the completed prism. thru; then carefully cut with a knife blade light of any description (whether from Now procure about 1% to 2 ounces car- till the slit is just thru. The length of this a gas, oil or electric source) is past in a bon disulfid from a drug store or chemical slit must be one -third the diameter of the narrow band thru a prism, it is broken supply house, and fill the prism with it, us- lens used. This slit is shown in Fig. 5. up into its component colors. On this ing if necessary a small glass funnel made This completes the parts. All that now re- fact is based the principle of the Spectra- by drawing and widening out a piece of mains to be done is to assemble the instrument. This is done as follows: The lens is placed in one end of the larger tube and the "slit" disc in the smaller tube. Leas Poste -boofd tubes. The assembled apparatus is shown in Fig. 6. The prism is glued on to a piece of pasteboard, which is in turn glued on to the base -board, the base measuring 9" long by 4" wide and g" thick. The collimating tube, as the pasteboard tubes are called, is fastened on with strips of tin. A groove is cut around the prism base to take a small pasteboard box, Fig. 7, which must be care- fg. 7 fully blackened inside. is use, and (E The apparatus now ready for an ordinary telescope or a lens placed The Finished Spectroscope, Which May Be Constructed at a Cost Not Exceeding One against the spy hole will magnify the spec- Dollar. Every Student of Science Should Familiarize Himself with the Workings of in This Instrument. trum if a gas or electric light is placed front of the slit, when a band of colors will now a colorless scope, an instrument that is considerably glass tubing, Fig 4. Plug up the hole with be seen in the spy hole. If flame is placed in front of the hole (as an used in both Chemical Analysis and various a small cork afterward. If experimental work. An instrument of the Next, procure from an optician's reading alcohol lamp) no spectrum will be seen. kind here described can be made now a little salt (sodium chlorid) for about one dollar and will is introduced into the flame on a prove a welcome addition to any wire, a yellow band will be seen experimental laboratory. in the spectrum. If a potash salt The main requirement is a is used, a violet band. If a lime (calcium) salt, a whole collec- prism, and the best and most lm efficient form is made as fol- tion of reds and yellows and lows: Procure, or cut a piece greens, is seen. Many further Source of in of glass tubing of 1 inch bore light experiments will be found on or and 1TA inches long. Break any text -book Chemistry this with a glass cutter or the Physics. wards of a key, till it has the Co///ma/or Note: Great care must be shape shown in Fig. 1. Those taken to keep the carbon disulfid who do not want to make the away from flames, as it is ex- prism can purchase one at small Arrangement of spectroscope tremely inflammable. cost from any optical shop. Then [Editorial Note: A sequel fig. 6.4 EE grind the edges smooth by rub- article describing experiments Plan View of Spectroscope, Showing Position of Flame Under Test, with the spectroscope will ap- bing on a piece of emery cloth Eye and Telescope, Prism, and Collimator moistened with turpentine in or Focussing Tube. pear in an early issue.] which a little camphor has been dissolved. glass, a lens having about Finally grind on very fine emery paper 12 inches or less focus. until the edges are smooth and at an angle This will cost about 35 to of 60 degrees (Fig. 2). Then drill a small 50 cents. Proceed to make hole in the upper side of the prism, or if a tube by rolling up sev- the tube used is thin chemical glass tub- eral thicknesses of brown ing, the hole may be made by heating (be- paper into a tube about the fore grinding) the side of the tube with a diameter of the lens and small blowpipe flame with the ends corked about 10 inches long. Make up. The heated air in the tube having no a similar paper tube to l other room for expansion will blow out a just fit into this about 6 f small projection, which can be filed and inches long. These two smoothed off. When this method is not tubes must be blackened available, the hole can be made by drilling inside. The black pigment with the broken point of a round file. When is made as follows: this has been done it should appear as in Moisten a little lampblack Fig. 2. with a very little kerosene Now cut or procure two pieces of flat and rub on to the inside Spy hole. glass about 1% x 15/2". These must be of the tubes. This must cemented on to the ends of the glass tube. not dry shiny. figs The cement for this purpose is made by The last item on the list dissolving some glue in hot is water and add- the slit. This is made 'Bross disc ing a little glycerin. Care must be taken by taking a circular piece f/g 4 fig. 6 EE not to smear the glue over the glass. If of brass or copper, mark- these directions have been followed ing a Details of Home -Made Spectroscope, Showing How the Prism care- line exactly across Can Be Made from a Piece of Glass Tube and Two Sheets of fully it will have the appearance shown in the center; filing till half Glass.

www.americanradiohistory.com August, 1918 ELECTRICAL EXPERIMENTER 251

A FREAK SELF -CHARGING ELECTROSCOPE. With this piece of apparatus you can Clockworks Without Gears puzzle those of your friends who think By THOMAS REED they know something about electricity. The constructional details are illustrated herewith. A brass tube of any desirable SOMETHING tells me that many "Bugs" The front and back plates of the frame- length and a glass tube that will make a would have liked to make an electric work E as well as the posts F may be made snug Yet inside the brass tube is required. clock as described in my articles last of wood. The glass tube is to hold the dry pile summer, but 'were discouraged by the dif- that charges the gold leaves. This is made ficulty of the wheelwork. I don't blame by taking several sheets of bond paper and them. Geared movements are hard to make, f coating one side of each sheet with a thin there's no disguising the fact. coat of bronze paint and the other side with But I'll tell you now how to make a oxid of manganese. Now lay the sheets movement without any gears at all -with- on top of each other after they have dried, out even the use of a lathe, if you haven't E side a S.^o,ar all the same side up, so that a bronze one, tho lathe would make a prettier IV/74"/ and an oxide of manganese side will always looking job. Second hand

be together. The trick consists in substituting for the A Take a leather punch that has the same gears, plain wooden flanged pulleys, with , inside diameter as the glass tube and with very small rubber bands for belts. a hammer proceed to cut disks out of the Of course this construction couldn't pos- several thicknesses of paper. As fast as sibly be used in a mechanical clock, for in I Hour bond they come thru the top of the punch they those clocks the driving power is applied Kij. w oi' / into A should be carefully pushed the glass in a relatively large mass, by spring or _ tube. Continue this until the tube is full, weight. No belt could hold that stored coating more sheets if necessary. power, and retail it out without slipping or j ¡ jMfflu/;nnd Now take the brass tube, solder a brass undue tightness. ball on one end of it, insert a wad of But in the electric clock, the power is

tinfoil in the glass tube and push it up into applied at the other end of the train, in II the brass tube. In this way contact is very small quantities, but constantly. So A the pile and the brass II N made between dry the only power or strain ever present in 1141 tube. the wheelwork is such as one dry -cell can The brass tube is now inserted into a produce, spread over eight months; and if cork and its end fitted with a small stir- you'll calculate that for any given moment Mr N¡2 rup to hold the gold foil. The open end (in terms of flea-power) you'll see that a r 'of the tube may be plugged with fiber if thread -like rubber band, tight enough only I desired. to keep it straight, will easily transmit that The trick electroscope is now complete; power. allow it to stand awhile and the leaves Now, then. Your first job is to find, Ir will begin to spread, indicating a charged either in your sister's workbox or a notion state. Touching the ball with the finger store, some of those smooth glass beads, Ever See a Gear -less Clock? Here's One You will allow this charge to escape, but the the size shot nearly Can Make with Rubber Bands for Belts. The of and as spherical in Pulley Ratios Are as Follows: G. 1/4 in. H, dry pile will again charge it. The elec- shape that are (or were) used in fancy In. to /tto tricity is formed by the dry pile in the work. Ratio 1 to 6; L, 14e In. to M, i n., Ratio i to 4; same manner as in the Volta pile. The N, %4 In. to P, a/4 In., Ratio 1 to 3. bronze paint and the oxid of manganese form the electrodes of the cells and the The outfit above described may seem un- slight amount of moisture present in the substantial, but I'll guarantee it to outlast paper is the electrolyte. the lifetime of any one of you. The rubber These cells have a very long life and bands, of course, would have to be re- the one described will continue to charge newed every three or four years, but every- the electroscope for several years before it thing else would easily withstand such wear finally gives out. as it would get. A is the brass tube; B, brass ball; D, glass tube; I, paraffined cork; F, tinfoil; CHEMICAL "SPONTANEOUS G, gold leaves. COMBUSTION." Try this instrument on some wise guy Purchase from your nearest drug store who always likes to show his superior ) a small quantity of perchlorat of potash knowledge of things electrical. (potassium chlorat). Then powder a Contributed by THOS. W. BENSON. Detail of Gear -less Clock as Described by lump of sugar in a mortar; after which the Mr. Reed. A -Glass beads; B- Wooden Pul- two are mixed to the following proportions leys; C- Cardboard Flanges and D -Arbor (one part of loaf sugar to two parts of of Knitting- Needle Stock. potassium chlorat). Caution : -Do not mix in the mortar, but Having found your beads, find some either on a paper or in a dish. knitting needles that will just go thru the When ready for the combustion, place a holes, fitting well, but not tight enough to small quantity in a tin or old dish and add bind. These will give you your "arbors" one drop of sulfuric acid (HI SO.). or axles (D, in the figures) and the beads Contributed by A are to form the shoulders, to keep the W. DOUGLAS GELDERT. arbor running in the proper plane. The beads are attached to the arbors by CELLULOID CEMENT. sealing wax, hard pitch, or rosin. Hold the Herewith is a formula for celluloid or bead in the proper position, and after ap- film cement. plying the wax or rosin, heat it by hold- Formula : 4 oz. collodion ing a hot nail near, till it bubbles and runs, ' 3 oz. ether and adheres firmly to both the bead and 1 oz. denatured alcohol arbor; don't rely on simply dropping the 1 oz. camphor. wax on to cold surfaces. Mix thoroly, then add 2 feet of moving The pulleys B can be jig -sawed out of picture film that has had the emulsion re- thin wood, such as cigar box material, and moved. the faces smoothed carefully. The diame- Contributed by GEO. W. LUCE. ters, of course, are very important; but a little eccentricity or wobbling, due to not GLASS -BLOWING LESSONS. drilling the hole quite accurately, won't In the September number there will ap- matter, as that will be taken care of by the pear the first paper of a series by Prof. Want to Have Some Fun with That Smar rubber band. The flanges C are separate Herbert Metcalf on the art of glass -blow- Electric Friend? Try Him On This Self discs, cut out of cardboard and glued to ing. These lessons will explain every step Charging Electroscope and Hear Him Rave with clear illustrations, so that you can About Electrons, the Quantum Theory, ad the pulley. The pulleys are fastened to the infinitum. arbors in the same way as the beads. learn the subject easily.

www.americanradiohistory.com 252 ELECTRICAL EXPERIMENTER August, 1918 Experimental Mechanics By SAMUEL D. COHEN

LESSON V.

THREAD CUTTING inches diameter. In other words, we must tool is fed to the work. When the tool is HAVING become thoroly familiar carefully consider the diameter of the stock withdrawn after the cut has been taken, it with the changing of the spindle, being threaded. is wound in again before taking the next lead, and intermediate gears on In actual practise, however, it is not neces- cut, so that the chalk mark is in exactly the the lathe, the student will be in- sary to make a separate tool for each same position as before. This shows the structed in the present article re- pitch of thread when cutting "V" threads position of the tool during the previous garding the subject of thread cutting, by of reasonably small pitch and diameter, the clearance angle given to the cutting edges of the tool usually being sufficient to allow for variations in the rake of the thread. It is very essential to see that the tool is Tao/ ground to the correct shape. One way is to grind it to fit between the threads of an ordinary plug -tap, but a special screw cutting gage is provided for such purposes, and it is advised that this should be in the ama- Thread. teur's tool kit. Fig. 3 shows how it is used gage and how it helps in properly setting the tool with respect to the work. Illustration Tnreaógoge in Fig. 4, shows how to set the inside Threading thread- cutting tool with respect to the work lao/ - with the use of the center or thread gage. fiq .3 It will be noticed that a flat steel plate "P" fig. 4 e is laid across the end of the work W' Setting and Testing the Thread Tool for to form a true surface for the end of the How an Internal Thread Cutting Tool Is Set Cutting External Threads, by Means of a gage to rest against. and Checked Up with a Center or Thread Thread or Center Gage. Gage. The Gage Is Squared Up Against a Having carefully considered the pre- Steel Plate Set on the True End of the Work. liminaries of this topic, we shall go into the taking up the successive operations neces- actual cutting of threads on the object. The sary to cut a sharp, accurate thread. cut, so that the operator can now readily work being mounted between the centers han- The first and very important considera- and firmly secured to the face plate by judge how much further to turn the tion in the cutting of a thread is to see that means of the dog, the tool properly ground dle around to advance the tool sufficiently the object is properly secured to the live and fastened to the tool post of the slide for the next cut. This done the old chalk spindle and to see that the article is revolv- mark is wiped out, and a fresh one substi- ing .truly on its axis. In lesson III the tuted, the marking being repeated as each writer has given full particulars how to successive cut is taken. find the true center and how to secure the Some lathes are provided with a small work to the spindle by means of a dog. graduated disk on the handle of the cross This means of support is very accurate and feed, a fixt pointer being attached to the suitable for all kinds of work. lathe carriage. In this case, of course, the Let us suppose the work has been secured expedients already described are unneces- in the lathe. The next thing is to provide sary. the proper cutting tool and to see that its The second or most important precaution cutting edge or face is properly ground. necessary to be observed by the novice is If we are to consider the cutting of an ex- that the tool shall follow in the same path ternal thread, we will use the outside thread - at each successive cut. There will be no cutting tool, Fig. 1; if an inside thread is trouble on this point when cutting any desired, the tool in Fig. 2 is used. It will be thread which is an exact multiple of the noticed that the tools used in thread cut- thread on the lead screw. However, if the ting are similar to the ordinary turning tool, lead screw has four threads per inch, and with the exception that their points are the screw to be cut has twelve threads per ground to 60° "V" shape, the angle of the inch, the work will always be in the right "V" corresponding exactly with the cor- position for the tool to follow in the thread rect angle for the screw to be cut. There when the carriage starting lever is engaged is one important difference, however, be- with the lead screw. It will also be true tween the shape of a turning tool, i.e., that if the screw to be cut has 8, 16, 20 or any the tool point is sloped or canted at an number of threads per inch which is divisi- angle. This is necessary in the screw cut- ble by four. This is true because the ting tool to prevent it from rubbing against Fig. 5.- Successive "Cuts" Necessary to Ma- change wheel on the spindle and the chine a Good Thread In the Lathe, Either the sides of the thread, owing to the slope External or Internal. change wheel on the lead screw are in ex- or rake of the latter. The rake of a thread actly the same proportion to each other as depends on the pitch of the screw and the the threads on the lead screw and the screw diameter of the work on which it is cut; rest, and the proper screw cutting change being cut. thus a screw of one -eighth pitch cut on a wheels in place, the lathe is then started and However, to cut a thread of twelve per bolt of one inch diameter, will have a a first preliminary cut taken along the work. inch, as in the case previously Mentioned, a greater rake or slope than that of a thread The tool is then withdrawn, the carriage wheel with forty teeth would be placed on of the same pitch cut on a bolt of two starting lever (see Lesson II) disengaged the spindle and a wheel with one hundred from the lead screw, the carriage is brought back to the starting point, and the tool is now set in a trifle deeper than before, the clasp being dropt into gear with the lead screw again and a second cut is taken. This series of operations is repeated until the thread is cut to a sufficient depth. A screw -cutting tool, by reason of its shape, is weak at the point and is therefore easily broken. Consequently, the depth of cut should not be greater than the tool can regulated The External Thread Tool Is Stronger Than easily stand, and this should be The Thread Cutting Tool, In This Case for the Internal Threading Tool. It Should Have in a systematic manner. A simple way is Internal Threads, Should Be Ground to Have a Good Clearance and Be Accurately Ground to mark with a piece of chalk the position Plenty of Clearance and Tested with a Thread to the Correct Angle. Self -hardening Steel or Center Gage. Is Often Used for Such Tools. of the cross -slide handle with which the

www.americanradiohistory.com August, 1918 ELECTRICAL EXPERIMENTER 253 and twenty teeth on the lead screw. The verse spindle the second cut is then pro- It requires only a little preparation and spindle would therefore make three com- ceeded with. This procedure is followed a slight knowledge of chemistry to pre- plete revolutions for each revolution of the until the thread is cut to the proper depth. pare some of this compound. lead screw, and the commencement of the The onlyobjection to this scheme is that Mercuric nitrat Hg (NO.). and ammo- screw thread on the work would accord- it wastes considerable time by running the nium sulphocyanat (or cyanid) are used in ingly be brought to exactly the same posi- tool post and carriage back each time. its preparation. In case these are not at tion in relation to the tool each time the The above scheme of set- starting carriage lever became engaged with ting the carriage with re- the lead screw. spect to the lead screw and Suppose a ten thread per inch screw is not disengaging therefrom desired to be cut instead of a twelve; then during the complete cutting the wheels required would be forty on the of the thread has been spindle and one hundred on the lead screw. found to give excellent re- The spindle will now make only two and sults. It is, however, ad- one -half revolutions, and the work will vised that the novice should therefore be half a revolution behind its become thoroly familiar proper position, thus causing the point of with the first as it will give the tool to come on top of the thread in- considerable practise in stead of in the groove between the threads, handling the lathe. if the carriage starting lever is engaged In cutting internal or in- with the lead screw. If the lead screw were side threads the same meth- allowed to make another complete revolu- ods are followed as when tion before engaging with the starting car- cutting an outside thread riage lever, the work will then make an- with the exception that an other two and one -half revolutions which inside cutting tool is utilized will bring it into the right position again and set as shown in Fig. 4. for starting the tool in the proper groove. It should be remembered, The work is therefore only in the correct however, when cutting in- Lathe Set up t o Cut External Threads on a Cylindrical Rod. position for starting a cut once during ternal threads that the di- The Stock to B e Threaded Is Fastened In the Chuck and Is every two revolutions of the lead screw, ameter of the hole should Driven by it. similar to other threads which are not exact be equal to the diameter at multiples of the threads of the lead screw. the bottom of the screw thread which is to hand the mercuric salt may be prepared by It will be found that to bring the tool to fit into it; thus the hole intended for an inch adding 75 c.c. of 1.2 sp. gr. nitrate acid the right position, the starting carriage bolt, having eight threads per inch on it, to 25 c.c. metallic mercury and slowly lever must only be engaged at intermediate would be bored out to just under seven - warming till all the metal is dissolved. The positions of the change wheel. eighths inch in diameter. excess acid should then be boiled off and the In order to prevent any mistakes arising, A very good illustration showing the concentrated mercury salt diluted to form the usual plan is to stop the lathe before the various cuts and the number necessary to about a liter of solution. tool commences its first cut along the work, make a good thread is given in Fig. 5. The ammonia salt is prepared by adding chalking a tooth on the spindle wheel and potassium cyanid to ammonium polysul- leading screw wheel, placing phid, and heating slowly to dryness. (A a tooth on the $$.$$.11111110111111111111,1.1111.111111,lll ,,.,.,..11.1111111 .,..,,.,.,,,,,11,,,1,,,1,11,111,,,1111111, another chalk mark on the headstock oppo- /MINI water bath should be used if possible; if site the former, and a chalk mark on the AUTHORS!!! not the container holding the solution lathe bed opposite the latter, the starting should be partly immersed in a larger con- cariage lever being then engaged with the All matter intended for publica- tainer holding water so as to form a double lead screw and another cut taken. The tion -not only by us, but by any boiler.) 25 c.c. of the KCNS (ammonium carriage is run back to the starting point other magazine or newspaper as sulphocyanid) should be dissolved in 500 c.c. after each cut and as soon as both chalk well -should be written on one side of water. Add 10 drops iron chlorid (Fe come opposite to the Cl.) to the Hg (NO.).. This will marks on the wheels ink. If it be used stationary marks again, at the same in- of the paper only and in as an indicator. Slowly add the KCNS stant, the starting carriage lever may be isn't, somebody else must copy part solution stirring constantly. A red color engaged with the lead screw and another of it off on another sheet before it of Fe CNS (iron sulphocyanid) will mo- cut taken. is given to the printer. mentarily appear but vanishes as soon as The writer has found from actual experi- the solution is stirred. A curdy white pre - ence that the above troubles relative to the «,,..,,,,, 1,,.,,,,1,,,,,,,,,,,,,,,,,1,,,,.1,,,,1,.1,ll ,.,,,,l 1,,,1 ,,,,,,,,,,, 1,,.,,,,,.,.,,.,,,,,,,, 1,,,,,1,1 1,,,,,,,,,,1 cipitat will form. When a point is reached advancement of the tool at each starting where the red color refuses to disappear cut can be remedied as follows: The first It will be found at first that the amateur the reaction is complete and no more of cut is started and ended at the proper place; will spoil a great deal of work before he the ammonium salt need be added. then the lathe is stopt at that point obtains a perfect thread on his work, and The precipitat should be filtered, washed Then withdraw the tool from the work, he is advised to continue to practise cutting and then about 1.5 g. dextrine disolved in and turn the spindle and work in the oppo- threads of all different pitches on old stock 10 c.c. of water should be added after re- site direction thus bringing the carriage until he thoroly masters the art. Old round moving the precipitat from the filter paper. and tool to the starting point without dis- stock should be used for practise work. The two are then thoroly mixed and then engaging the carriage from the lead screw. (To be Continued) dried for 48 hours. By starting the lathe in the proper cutting When dry, the cake may be cut into little point and setting the point of the tool with PHARAOH'S "SERPENT'S EGGS pellets of about inch cubed. A match ap- proper reference to depth and by noting the TRICK. plied to this will produce the snakes. position of the graduation on the trans- Caution :-The fumes given off when ONE of the most amus- burning are poisonous mercury gases and ing tricks in fire- care should be taken not to inhale them. works is the serpent's Contributed by ALBERT H. BEILER egg trick, where a little pellet when lighted, turns into a horrible snake, many, AMATEUR ELECTRICIANS! many times the size of the ATTENTION!! pellet. How awe -inspiring Did you read the prize contest it is to the youngsters! article entitled "Utilizing Burnt -out Most people have no idea Lamp Bulbs," which appeared in what in the world causes the the April number of this journal? snake to appear. The ex- If not, procure a copy to -day. Here planation is simple. Mercury is your chance to make some sulphocyanid burns with a money. Prizes are offered for the voluminous ash. The little best ideas -"What to do with burnt - pellet is nothing more than out lamp bulbs," and prizes will be some mercury sulphocyanid. awarded as follows: First prize, The heat causes the ash to $3.00; second prize, $2.00, and move off so quickly from third prize, one year's subscription the burning pellet that it to the ELECTRICAL EXPERI- writhes and distorts itself MENTER. Get busy, boys, and into the shape minia- nternal Thread -cutting Tool Set up on Lathe Carriage for of a watch for the September issue. Threading Inside of Telephone Receiver Cap. ture snake.

www.americanradiohistory.com 254 ELECTRICAL EXPERIMENTER August, 1918 On the Construction of Small Transformers By Prof. F. E. AUSTIN

AS many questions are continually aris- If, on the other hand, the single turns were For electro- welding only low pressures ing in the mind of the amateur and made of a band or flat ribbon of thick cop- are required, but large currents are neces- experimenter regarding the windings per, then short -circuiting the ends of such sary in order to supply the necessary heat on transformers to meet certain conditions, a turn would cause a very considerable cur- at the junctions of the two pieces of metal a few fundamental principles may be ex- rent, because of the very low resistance of to be welded. A transformer for welding plained that will enable those who so desire the band and a very considerable amount of purposes will therefore have its secondary to either construct transformers to meet electrical energy will be supplied by the made of very large copper bands, and con- certain requirements or to remodel trans- primary. sisting of but few turns. If the same num- formers already constructed to meet new In other words, it makes no difference ber or turns are wound on each limb or coil, conditions of service. what the cross -section of the wire is so far then the two may be connected together in Suppose a transformer has been con- as the induced pressure is concerned, but parallel, in order that the current may be structed similar to the one shown in illus- does make a difference so far as the current doubled. tration, having a core one square inch in is concerned. So far as the load on the In connecting the two coils together, it cross section, 6% inches long on the limbs, transformer is concerned, one turn of very will be necessary to duly regard the polarity containing the coils and 25(,. inches on the large wire will produce as great a load as of the terminals, as at every instant the shorter limbs. This core is made up of soft a large number of turns of fine wire. terminals have relatively positive and nega- iron plates, of, say, ordinary black stove It was said that the per turn pressure on tive relation with each other. If two coils pipe iron, or even of ordinary "roofing the primary is very nearly the same as the happen to be connected so that two positive tin," which is thin iron or soft steel coated per turn pressure on the secondary. Were and two negative terminals are together, the over with tin. The strips to build up the the efficiency of the transformer 100 %, resulting pressure will be zero, provided the iron core are therefore 1 inch wide, and meaning that just as much electrical power pressures of the coils are the same. the longer strips 6% inches long, and the could be obtained from it as was supplied to If the secondary winding of a trans- shorter ones 3% inches long. it, then the per turn pressure of both pri- former such as in the figure consists of two sections, each having two layers of 50 turns each of No. 14 B. & S. gage copper wire, the terminal pressure of each layer will be about 5 volts at a load of about 300 watts, ur a trifle less than one -half horse -power. If copper strip about IA inch in width is wound on or over the secondary of No. 14 forming 2 coils of five turns each, a welding transformer will be formed, allowing, II desired, the two windings to be connected together in parallel to produce twice the current but only one -half the pressure effect As described the transformer is a st, f- down transformer, stepping the applied primary pressure of 110 volts down to 5, 10, 15, 20, or 1 or 2 volts as desired by attach- ing to the proper terminals. If instead of being wound with No. 14 wire, the secondary were wound with say 1040 turns of No. 28 B. & S. gage copper magnet wire, the transformer would become a step -up transformer, stepping the pressure up from 110 volts to about 200 volts. Were a transformer capable of operating at 100% efficiency, then the pressure times the current in the secondary would be exactly equal to the pressure times the current in the primary. Then if the secondary pressure were twice the primary pressure, EE the secondary current would be one -half the primary current. This at once shows why a step -up transformer requires a smaller Typical Design of Efficient Closed -Core Transformer Treated On In the Present Article. size of wire in secondary than in the This Design is Adaptable to Either Step -Up Step Requirements. the Or -Down primary. In a step -down transformer the is much If this transformer is designed for con- mary and secondary would be exactly the secondary made of larger wire nection with a 110 volt service main, the same. If the efficiency of a transformer is than the primary. primary coils should be wound with a total 50 %, then the per turn ressure of the sec- of 520 turns of No. 25 B. & S. gage copper ondary is about one -halfthe per turn pres- magnet wire, double cotton covered. This sure of the primary. Of course the effi- PROPERTIES OF ELECTROLYTI- of course means 260 turns on each spool ciency of 50% occurs when the transformer CALLY DEPOSITED COPPER. or coil. If there are 520 turns total and the is in operation, delivering electrical power. applied pressure is 110 volts, the volts per At no -load output, or at open-circuited sec- A preliminary report has been publisht turn of the primary will be ondary, the per turn pressure of the pri- of the studies of copper electrodeposition 110 mary and secondary are the same in a well - in electrotyping baths by the U. S. Bureau = 021 volt. designed transformer. When, however, the of Standards. These studies have resulted 520 load is applied to a transformer, there is in establishing tentative specifications for Considering the matter from another stand- an internal pressure drop exprest by the the deposition of such copper, concerning point, about five turns represent one volt. resistance of the windings multiplied by the the composition of bath, current density, If now one turn of a secondary winding current in the windings. If the resistance etc. is wound on the spool or form over the of the windings does not vary in value but In connection with this work there has primary winding, one turn of this secondary the current does, then the internal pressure been publisht (Transactions of American will have between its terminals a pressure drop will vary. As the current increases Institute of Metals, 1916) an article, giving of very nearly 0.21 volts. If this one turn due to increased load the internal drop in- a description of the microscopic structure were of No. 25 copper, its resistance would creases, and therefore the terminal pressure of electro- deposited copper. The occurrence be so great that even were the ends of the decreases. and effect of twinned copper crystals or single turn brought into contact with each The applied pressure is kept constant and grains as deposited are discust. The con- other the current resulting would not be the demanded increase in energy is sup- clusion is reached that the grain size of great, and therefore no very noticeable load plied by the governing devices at the cen- such deposits does not alone determine the would be supplied by the primary. tral station furnishing power. physical properties.

www.americanradiohistory.com August, I 9 I 8 ELECTRICAL EXPERIMENTER 255

give some other alarm until switch "D" is opened. Handy Tape Holder and Cutter While a separate battery is shown in the bell circuit, a connection could be made The diagram herewith shows a handy tion would cause it to drop to one side to the gravity battery to ring the bell. friction Tape Holder and Cutter for arma- and close the contact. Another poor Contributed by open ture winders. Without such a device one feature in my estimation :-When the ROBERT M. WEAVER. is forever hunting for the tape, besides try- circuit line is closed, it will not unbalance ing to cut it with one hand. the relay, but only allow a larger amount A NOVEL ELECTROSTATIC /07/fe EXCITER. The little machine here illustrated is very convenient for exciting influence (static) machines and for a variety of purposes when a stream of very small sparks of either + or - electricity is required. It consists of a 3 -inch length of ebonite (hard rubber) tube, A, 1% inches in diameter, closed at the ends with corks, so that it can be fixed to an axle, B, of stout brass wire, passing thru holes in the center of two small pieces of varnished wood, C -C, 2% %/ 1;. / `I inches long. The ends of the axle are \\ afterward bent into handles, as shown. Two thick strips of ebonite, D D, 4% inches long, ti are screwed to the wooden end pieces. A hole is made in the center of each to take a at/ 3 -inch length of brass tube, which must 01101100i Mammon( make a tight fit. One of these has a collecting comb, E, soldered to one end and a large brass ball, F, screwed to the other. The second tube has a similar ball, G, fixt to one end, and a fur "rubber" H, at the opposite end. The rubber is 2% inches long and Y4-inch wide. It is curved, as shown at J, the degree of curvature being the same as that of the ebonite tube, and consists of a A Tape Holder and Cutter Useful In Every Shop and Laboratory. Which Can Be Made in a piece of any suitable fur (the writer has Few Minutes' Time by the Experimenter. The Clamp Is Best Purchased at Your Hardware used moleskin, though cat -skin is best) fixt Dealers. to a curved strip of brass with glue. The metal backing is, of course, previously sol- As all of us know, there is much lay- of current to flow thru the relay coils, dered to the brass tube. ing down and picking up of armature due to the fact that the 20 ohm resistance It will be understood that the rubber must winders' tools, and you are obliged to look is cut out of this circuit. press very lightly against the revolving all over your tray each time for the tool ebonite tube, while the teeth of the collect- you want. Now this device can be clamped ing comb must clear the tube by about %- to the tray just where it will be the most inch. The operation of the machine is very handy and will always be found in the simple. Upon turning either handle the same place when wanted. You can pull off ebonite tube is caused to revolve against the as much tape as you want, and then by fur -rubber. Both become electrified in con- pulling it sharply across the knife it will sequence, the fur positively and the ebonite cut the tape. One side of the arms that negatively. The capacity of the machine is, hold the knife should be longer than the of course, very limited, and only very small other and the knife set so that the tape charges accumulate on the metal conductors. will be cut on the bias. The knife, as you In order to obtain a constant stream of observe will do away with the handling of sparks, therefore, one of the conductors your shears. must be grasped in the hand to conduct As I find this a great aid to my work, away its charge as fast as it is collected. I pass it on to others. Hold F, and positive sparks are obtained Contributed by CHARLES A. SMITH. from G; hold G, and negative sparks may be taken from F, as long as the handle is Improved Circuit for Burglar Alarm, Using turned. BURGLAR ALARM Simple Yet Very Effective Arrangement of This is the reason for making a IMPROVED Relays. handle at both ends. CIRCUIT. Contributed by H. J. GRAY In,.your March, 1917, number of ELECTRI- I submit a diagram for your consider- CAL EXPERIMENTER, on page 821 is described ation which I think will work better and a "balanced burglar alarm system," con- be more reliable. As far as the contacts tributed by Mr. T. W. Benson, which I do are concerned, Mr. Benson's would work not think will work very good. The con- very satisfactory. In the closed circuit tacts shown in his Figs. 1 and 2, and the three gravity cells would be used. battery Fig. 6, I think are all very good. The two relays are connected in series. The balanced relay, Fig. 3, however, will Any style of relay having resistance of not operate exactly as described: If a about 35 ohms would work. The armature "polarized" ringer coil is used and the tap- of relay "A" is adjusted so that it will per arm bent so that it will drop to one stand normally open, but will close when side, and is connected as shown in his Fig. the open circuit contacts are closed, or if 4, the tapper will drop to one side accord- the line should be short circuited. Re- ing to the direction the current from the lay "B" has a back contact, and is ad- battery is flowing in, and stay there. I justed so that the armature is normally do not believe any adjustment can be made pulled up. When a dosed circuit contact to permanently balance this relay as shown. is opened or any change in the resistance If the permanent magnet would be removed of the line is made, relay "B" will open. from the ringer, the pull of the one coil Relay "C" (according to my diagram) would be equal to the pull of the other is so wired that when the contact on either coil, but as the tapper arm is slightly bent, relay "A" or "B" is closed, the contact on when the battery circuit is closed the tapper relay "C" will close and remain so, re- will fall in the direction it is bent, and gardless of whether the contacts of relays A Small Electrostatic Exciter Such as Here Illustrated Is Very Convenient for Exciting remain there. Even if it would be pos- "A" and "B" resume their normal posi- Large Static Machines and for Conducting sible to balance this relay, any slight vibrations. This will cause the bell to ring, or Simple Experiments With.

www.americanradiohistory.com 256 ELECTRICAL EXPERIMENTER August, 1918 Experimental Chemistry By ALBERT W. WILSDON

Twenty -Seventh Lesson

WATER: History jet of hydrogen in air, and hold over the and solids when they pass from one state flame of a cool bell -jar, which will im- of aggregation into another. With ice or WITH the observation of Caven- or liberation was the mediately become coated with a film of water this heat consumption dish in 1781, that water amounts to 79 calories. That is, in order to product of the combustion of moisture. When a mixture of the two a fuse 1 kilo of ice, a quantity of heat will be hydrogen, the ancient belief in its gases is brought in contact with flame, a violent explosion results. If, however, required which is capable of raising 79 elementary nature was broken moment kilos of water thru one degree centigrade. in 1873, confirmed the ex- they are brought together at the down. Lavoisier, as to prevent experiment of Cavendish, and he decomposed of their combination, so Water is the greatest solvent known. plosion, the mixture will burn with a very Substances dissolved in it raise its boiling intense heat. The oxyhydrogen blowpipe point and lower its freezing point. this may be ac- C/osing end with thumb is the apparatus by which complisht. Reference is hereby made to Experimental Chemistry, Fifth Lesson, Oc- Unfiltered water tober, 1916, issue of this journal, for a more complete description of the blowpipe with illustrations. Graduated on Composition. Sono' one side Analytically, the composition of water 6rOrel may be demonstrated thru the electrolysis of water (acidulated with a small quantity of sulfuric acid) which when carried out by means of an eudiometer, yields two vol- filtered wo /en free from derrnS umes of hydrogen, which collects in the arm f/y /25 containing the negative electrode, and one tUfig. /24 volume of oxygen in the other containing How Water Is Filtered by Means of Filter the positive electrode. Beds Constructed In the Manner Illustrated. Eure's "Eudiometer," a Graduated Glass Synthetically the composition of water The Unfiltered Water Enters at the Top and Tube, Used In the Analysis of Water by Trickles Down thru the Sand and Gravel Electrolysis. may be proven either by volume or weight. Layers, Which Purify It. Volumetrically, by introducing exactly 1 water into its elements and conclusively volume of oxygen and 2 volumes of hydro- Evaporation takes place at all tempera - demonstrated that it was composed of one gen over a column of mercury contained in tures, even from ice. Evaporation increases part, by weight, of hydrogen, and eight an eudiometer tube (see Fig. 124). After in rapidity with the temperature and di- parts, by weight, of oxygen. The volu- exploding this mixture by means of an minishes with the increase of pressure and metric composition was proven by Gay - electric spark, all the gas will have dis- tension of the aqueous vapor of the atmos- Lussac in 1805 to consist of two volumes appeared and the tube will be filled with phere above. of hydrogen and one volume of oxygen. mercury, excepting a very small quantity It has the highest specific heat of liquids. Occurrence. of water which has been formed. Should Aside from its abundant natural occur- the two gases introduced be in proportions Chemical. rence, as we are accustomed to see it, water other than the above, any excess of one Water begins to dissociate at 1000 deg, is very widely distributed in such a manner or the other will remain after the ex- but is completely broken up at 2500 to 3000 as to evade casual observation. In other plosion. Gravimetrically, the quantita- deg. Thus it is one of the most permanent words it is in places where we would be tive synthesis of water is carried out by of compounds. Below the latter points it least likely to look. It is present in green conducting pure dry hydrogen over a will extinguish flame, but above them it plants to the extent of from 70 to 90 per weighed quantity of heated copper oxid, feeds the flame. cent; in fruits 80 to 95 per cent; in the the resulting water being collected and It decomposes electrolytes into plug and animal body from 75 to 80 per cent; while weighed. The weight of the copper oxid minus ions. the is noted. loss K, the soil averaged from 5 to 20 per cent of after reduction also The It reacts with certain metals -Na, Li- moisture. in weight sustained by the copper oxid rep- to form alkalies. Thus Sodium and Potas- Preparation. resents the oxygen consumed, and this sub- sium, as we have seen from experiments The simplest and most convenient method tracted from the water formed is the hy- already conducted, decompose water at of forming this compound from its ele- drogen. For example: 6.57 grams of cop- ordinary temperature with the liberation of ments, i. e., hydrogen and oxygen, and prov- per oxid lost 1.31 grams of oxygen, which Hydrogen. K, + 2H, O = 2KOH + IL. ing the product to be water, is to burn a in turn yielded 1.475 grams of water. The With metallic oxides it often forms bases. hydrogen consumed would be equivalent to (Continued on page 273) C 1.475 - 1.31, equals 0.165 gram. Then the ratio of hydrogen to oxygen would be 0.165 to 1.31, or 1 to 7.94, which represents the A Irl ar.efe .,rf;eed combining weights of these two gases. Sporn e/eC/rodes w.er Since the vapor density of water is 8.94, its sea/ed/no/ass /the T:ec: molecular weight must be 17.88 (2 X 8.94.), 2 parts n ^ad ;te ed wo/er and of this by weight, or two atoms, pressfire are hydrogen, and 15.88 parts by weight, or one atom, of oxygen. C 6r '' far'-;;ered Tube mn/ainizsj z ro/urnes natter Properties: Physical. of hydrogen on d! Warnee of oxygen over mercury Water consists in three states, i. e., solid, (ice), liquid, and gaseous (steam) within -Steam Jochet 100 degrees (C). It freezes at 0 deg. C. and boils at 100 Rubber tube to deg. C. at 760 mm. pressure. Under 10 at- /oIrmercuryto mospheres it boils at about 180 deg. Di- Yearn Pinch cock: a/ minished pressure lowers the boiling point. ealershere expand The specific gravity of water at its greatest density has been selected as 1.000; at 0 fig /26 deg. it is 0.99987, thus ice (0.9173) floats in fig. /27 0 water. The Pasteur Water Filter. The Germ -laden When water crystallizes, heat is set free, Water Enters at the Bottom and Is Forced Simple Experimental Apparatus to Be Made Thru a Porous Clay Tube "B," from Which while, on the other hand, when ice is fused, by the Experimenter for the Synthesis of the Purified Water Emerges Thru Pipe "C." heat is absorbed; this is true of all fluids Water.

www.americanradiohistory.com August, 1918 ELECTRICAL EXPERIMENTER 257

This department will award the following monthly prizes: First Prize, $3.00; Second Prize, $2.00; Third Prize, $1.00. The purpose of this department is to stimulate experimenters towards 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 $3.00 is awarded; for the second best Idea a $2.00 prize, and for the third best prize of $1.00. The article need not be very elaborate, and rough sketches are sufficient We will make the mechanical drawings. Use only one side of sheet. Blake sketches on separate sheets.

FIRST PRIZE, $3.00 SECOND PRIZE, $2.00 THIRD PRIZE, $1.00

A MILK BOTTLE ALARM. A CIRCUIT- BREAKER FOR BAT- A USEFUL HAND DRILL A is a piece of brass cut as shown in TERY CURRENTS. ATTACHMENT. Fig. 1, with a piece of tape or fiber (for in- This circuit -breaker, of which a sketch is Its principal function is to hold the hand sulation) as shown. B is a piece of spring here given, has proven to be very efficient. drill straight, thus making it easier to do brass cut as shown and both ends of A and The base and uprights may be made of box- . accurate work. Dimensions are left to be B are separated by a piece of hard rubber wood. The binding posts may be obtained from an old battery; the magnet can easily be made or obtained from a discarded door- bell. The dimensions may be altered but I have found the ones given very convenient. In making parts "a" and "b" care must be taken to allow for the bends at "d" and "F." The height at "d" depends on the size of the magnet; the same with the length of "a." Point "y" must fall below "x" when "z" touches the core of the magnet. Contributed by CARL KOESTER.

When the Mllkman Takes Your Milk Bottle from This Switch, it Closes an Electric Alarm Bell Circuit. To Drill Holes Accurately With a Hand Dr!! is Always a Difficult Job. This Vise Attach- with tape wound around them, or else ment Makes a "Drill Press" Out of Any clamped together by fiber blocks. Place a Hand Drill. on bottle the brass arm B, and as soon as calculated by anybody picks up the bottle, it causes a the builder to fit his particular drill. The main 1 connection between A and B and the bell standard "A" inch by rings. 3/16 inch band iron, is formed by drilling Contributed by several holes in one end and then bent at EDWIN WOLBER. an angle to fit the flat anvil on an ordinary vise. A slot may be cut in it by drilling A SIMPLE PITH -BALL "ELECTRO- several holes in a row, chopt out with a SCOPE." cold chisel, and finished with files. The upper part of standard "B," is also made of A simple but electroscope is efficient 1 inch by made 3/16 inch band, then it is bolted as follows: A bottle made of good, loosely to "A," with washers and nuts on clear glass and of the shape shown is neces- opposite side. A clamp made of lighter sary. A thin copper wire is bent in the material is bolted shape indicated after to the top to receive hand being mounted in a drill. To operate it is only necessary to tight- fitting cork. The copper wire is apply pressure to top of drill. mounted in a poured sulfur bushing in A Miniature Circuit- breaker Such as This Contributed by LEO the center of the cork. A piece May Save the Life of Your Batteries Many HAASE. small of Times. silk thread is tied or pasted to each pith -ball rent is allowed to flow long enough the and the other end is tied to the hook in the water becomes heated. wire. When finished of the bottle. Be sure the pith -balls hang the pith -balls should exactly even in Contributed by GEO. B. GATES. hang two or three inches from the bottom the bottle. Contributed by MANSELL SARGENT. A pretty experiment, but our contributor has taken a wrong conclusion. The tumblers TESLA CURRENT PASSES THRU with water, the inside wire, as well as the GLASS. outside loop forms a small Leyden jar (a When amateur wireless stations were closed by the government, upon the entrance of the United States into the war. many operators constructed Tesla coils and resonators for use with their transformers. I am submitting a description of an experiment which requires practically no preparation, and which has a startling effect. The fact that electricity at high voltages cannot be confined by ordinary electrical insulation is well illustrated. The action is as follows: When current flows Apparently the Tesla High Frequency Cur- thru the Tesla coil sparks leap from ent Passes A and A, to Thru the Glass of the Leyden the surface of the water. A . Jars, Causing a Discharge at the Gap G. steady stream of sparks also flows between D and D, at the gap G. A Handy Testing Instrument for the Ama- The electricity evi- condenser). Hence the easy flow of the eur Electrician Is the Pith -ball Electroscope dently flows from A to A,, thru the glasses current. However, Tesla currents easily Here illustrated. without puncturing the glasses. If the cur- pass thru glass.- EDIroit.

www.americanradiohistory.com 258 ELECTRICAL EXPERIMENTER August, 1918

EGITED BY S. GERNSBACK

DRILLS MADE FROM NEEDLES. taking an ordinary wood screw and filing "THE SYNTHETIC PRODUCTION Having occasion to use many small drills, down each side of the head, as shown in the OF RUBIES." and not wishing to incur the expense of illustration. During the last few years, practically all continually repairing old ones, I used the It will readily be seen that while it can of the beautiful minerals of the corundum following trick: be screwed into the wood, it cannot be un- family have been produced synthetically in I procured several sewing needles of the screwed. same diameter as the drill I needed. After Contributed by G. COLEMAN. breaking off the eye, I ground the needle slightly flat on both sides of the large end. I then shaped the flattened end according A CHEMICAL SIPHON. These do to the sketch. drills will good This will be especially useful to electro- work and will not break so easily. off from by R. DANKS. chemists for siphoning liquids Contributed gravity batteries, etc. It is easily made by REMOVING STAINS OF ALL heating a glass tube till soft and drawing KINDS. it out until of quite small diameter at the bend; it is bent as shown in sketch (aided Solution No. 1. 20% solution of acetic by using a fish tail burner). acid or tartaric acid. Its principle of operation is the "ram" Solution No. 2. Five grams of bleaching action. Immersing it, keeping one finger powder (CaCIO). Boil in 100 cc of water closed over one end, and lower it horizon- until a pink color appears. Filter and add tally into the shallow liquid. Remove finger 50 cc of cold water. and liquid will rush into tube, its velocity To remove ink, coffee, tea, fruit, and dye being sufficient to carry it up the narrow stains, wet the spot thoroly with No. 1. portion marked N, and over the bend. Absorb the superfluous liquid with a blotter Contributed by K CLARK. and apply No. 2. Rinse and repeat if necessary. For removing common stains, treat as shown in the following table: STAIN REMOVED BY Acids Cold water, Nos. I & 2. Grass and fruit Cold water, alcohol, Nos. Do You Know That Rubies Are More Val 1 and 2. uable Than Diamonds? With This Furnace Grease Gasoline, carbon tetrach- You Can Make 'Em By the Pound. Don't lorid, chloroform, ether, Forget to Send Us a Few Poundal. carbon bisulfid, ammonia, soap-suds, warm fullers the laboratory. These artificial gems are earth (cover with a blotter and apply a warm identical in beauty, hardness, and chemical Slurp y Bend a P ece of Glass and Prestol composition those obtained from the iron.) That Much Desired to Dyes, coal tar or of Siphon Is Ready. Simple) mines. The accompanying diagram shows a vegetable origin Nos. 1 and 2, ammonia. furnace commonly used in producing the Mildew Nos. 1 and 2, sunlight. Inks Nos. 1 and 2. gems. Inks, indelible (sil- A HOME -MADE CARBON The operations are as follows: ver) Potassium cyanid, 10 %. CRUCIBLE. A trace of chrome alum is added to a Use great caution - intensely POISONOUS, It is often that the experimenter desires solution of common alum, the chrome alum Sodium hyposulfite 20% to melt a being the coloring constituent. solution. small quantity of metal and mould it into a certain shape, or he might Then ammonia is added and a gelatinous Iodin Methyl alcohol, potassium precipitat of hydrates of iodic' Sol. 10 %. want to mix a special amalgam. But he is the alum and Iron Rust Warm oxalic or citric acid, stopt by the lack of some suitable container chrome is formed. 10 %. If in silk, let it This precipitat is filtered off, evaporated alone. or crucible; and he does not want to buy Paint, varnish Turpentine, benzine, car- to dryness and calcined in a furnace at a bon tetrachlorid. Use no temperature of 1000° F. into an ultimate turpentine on silk. //////////N//////y//U/ mixture of alumina and chromic oxid. The Tar, wagon grease Soap and oil, turpentine. proportion in which these two chemicals Contributed by JOHN D. COLEMAN. occur in the ruby are: Alumina 98% A WOOD SCREW WHICH CANNOT Chromic Oxid 2% BE UNSCREWED. The mixture is then ground into a powder Many times the experimenter has need of and placed in the hopper "A." "B" is an a wood screw which can be screwed into a electrical tapper which shakes the powder thru the sieve "C" into the tube "D." Thru this tube the oxygen is also supplied. Hy- drogen is supplied thru the tube "E." The two gases are ignited at "F." "G" is a Make Your Own Crucibles and Build an Elec made a highly trio Furnace to Make Diamonds. -S'easyl platform of refractory substance against which the flame strikes and on which the ruby is formed in a pear - one. Herewith are given the directions for shaped mass. The rate of flow of the pow- making a crucible that will stand a very der and the temperature of the oxy- hydro- high temperature. gen flame must be regulated very carefully. From a round battery carbon cut a piece When a bead of sufficient size has formed 15/2" long. From the top drill a 5" hole the heat is gradually lowered so that the 1% "deep. Round off the bottom and the gem may be free from great stresses. result will be a good carbon crucible. The When it has cooled, it is broken off the contributor has melted iron in a Now Don't Get All Mother's Needles. Re- crucible base and sent to the cutter who finishes the member She Has to Darn Your Stockingsl- of the above design. By using a dry gem. And You Can't Unscrew This Wood -Screwl plaster of Paris mould the metal may be It is important that the ingredients used cast into the desired shape. in producing the minerals be of the purest piece of wood, but cannot be taken out. A Contributed by obtainable. screw of this kind can easily be made by WILLIAM F. WINTER, JR. Contributed by W. A. SCHILDKNECHT.

www.americanradiohistory.com August, 1918 ELECTRICAL EXPERIMENTER 259

Wave- Motor. operator when ready to send, simply small firearms such as pistols and Electrical Torpedo Net. (No. 1,263,888; issued to Leander pushes the switch trip to the left or revolvers, for the purpose of light- (No. 1,264,926; issued to Albert W. Hammond.) against the pin on the knob, and ing the target in the dark. Hedina.) Adapted to amateur requirements proceeds to transmit. As soon as By means of two switch buttons A net which may be used in sec- in developing electric light, etc. The the knob isi released, the switch tions, or which can be utilized sep- paddle member, which is pivoted so closes automatically. arately by being arranged on a boom swung outwardly from a ship or in Talking Motion Pictures. groups, so as to form a continuous (No. 1,260,337; issued to Richard curtain about the ship. This net is M. Craig.) provided with a series of oppositely He utilizes a film containing the charged and specially insulated elec- motion pictures, and on this same trical conductorst arranged in such film he also records the speech rec- a manner that if a metal torpedo ord in such a manner that the sound shell hits the net, it will cause a record is formed of a substance current to flow thru the torpedo which does not affect the transmis- from the oppositely charged con- sion of ordinary white light but ductors, and by virtue of the resist- which will affect the passage of rays ance offered by the passage of this beyond the visible rays of the spec- current thru the shell of the tor- 3_.-ti trum. Also, the sound record on the pedo, will thereby cause heat to be film is made capable of transmitting generated, and this heat in turn to ordinary white light, but is im- cause an explosion of the torpedo's as to be swung back and forth by pervious to the transmission of infra- gun-cotton charge. the wave action, is supported in an red rays. The patent covers details at the rear of the battery case, either adjustable frame, which rises and amp can be lighted. One lamp lens falls with the tide, thus keeping the gives angle light for the use wave paddle at the proper height to ves a flashlightwhite g general illumina- work effectively at all times. The tion, and the other lens a small angle to-and-fro motions of the paddle beam sharply focust for use in cause a mechanical connected pump lighting a target. to force water into a tank in the manner apparent. The supply of Sound -Reproducing Diafram. water, which may be under pressure (No. 1,264,219; issued to John A. in the tank on shore may he utlizerl Steurer.) for operating a water turbine or the Diafram made, for instance, of like, the turbine being connected to blotting paper. This is saturated a dynamo, etc. with a thin solution of a phenolic condensation product, such as Bake- Electric Horn for Autos. lite or condensite, which is then (No. 1,264,841; issued to Henry A. whereby the film moves intermit- dried. A circular central portion of Neuwiller.) tently past the image projecting the diafram so formed is then treated A. C. Induction Water-Heater. A unique electric wind born for lens, but moves steadily thru a with a greater amount of the solu- (No. 1,261,470; issued to Charles A. autos and other vehicles which has second translating chamber ini which tion of such condensation product, Backstrom.) a particular application to a sound - the invisible or infra -red rays are and this part of the diafram is then An induction type of electric producing instrument, wherein the projected thru the film and caused water heater intended for use on al- air currents are generated by means to fall upon a suitable electric in- ternating current circuits. This de- of a motor-driven fan. When the strument (bolometer or tasimeter) ' sign of heater has for one of its ob- whereby the fluctuations of the in- jects a higher operating efficiency, visible rays will cause the reproduc- whereby a loss in the return mag- tion of sound vibrations in an as- netic circuit is utilized for heating sociated electrical circuit, containing the water. As shown, there is loud -talking telephones. provided a U- shaped iron core on which the magnetizing coils are (No. 1,263,204; issued to Elmer E. wound. At the upper end of the Radio Receiving Circuit. core a hollow cap plate is held in Butcher.) Intended to operate with aerial or other collecting circuits which are out of resonance with the received permitted to dry, with the result oscillations, contrary to the usual that the central part of the diafram motor circuit is closed, it quick y practise, their purpose being merely will absorb a much larger quantity accelerates the fan which draws 'n to intercept them and transmit them of the solution, and secondly be air thru screened openings at the much more dense. The diafram is rear of the fan chamber. In emerg- baked to make it hard and elastic, ing thru the horn member the cur- and it has a uniform thickness, rent encounters a series of tuned while possessing much different musical reeds, which may be three characteristics from an ordinary dia- or more in number. In this way the fram of uniform density. reeds are vibrated by the air currents passing by them. Heavy Current Microphone. (No. 1,263,140; issued to Lonnie Telegraph Key Circuit-Closer. Burnett Stone.) (No. 1,264,465; issued to James L. A novel design of heavy current White.) or high duty telephone transmitter, On the top of the key knob is a employing a plurality of micro - small lever which is normally held phonic units. These multiple mi- in such a position that the lower end crophonic units, which comprise a of this lever permits the switch to the detector, which may be of the series of tubular chambers or shells knife to close the circuit in the well- crystal or vacuum valve type. As in which carbon granules are place, the diagram shows the detector is connected unilaterally. The variable are connected in multiple with a condenser, 4, is not absolutely ne- suitable induction coil having a cessary; 6 is a variable inductance, three -part primary winding. and 7 a variable condenser. Coil 6 is preferably of considerable length, with a large inductance and a relatively low distributed capacity, and acts as a linear oscillator, thus producing a point of maximum potential to which the detector is connected. Condenser 7 fias a relatively small position by means of machine screws capacity, while the inductance, 6, or bolts, this cap plate being made is principally used to tune in the of iron or steel. The hollow pas- received oscillations. sages thru the upright coil cores register at their upper ends with the Flash -Lamp for Firearms. passageway thru the cap, so that (No. 1,262,270; issued to Paul when water is admitted at the bot- Schmidt and Carl Dobslaw.) tom of the heater, it will pass thru This patent covers a design for the hollow cores and be discharged known manner. A spiral spring an electric flash -lamp adapted to be at the upper end. When connected causes the switch knife to be nor- detachably secured to the barrels of to alternating current, the reduced mally held in the switch jaw mounted core cross -section causes considerable under the lower key contact. The COPIES OF ANY OF THE ABOVE PATENTS SUPPLIED AT 10c EACH heat to be developed.

www.americanradiohistory.com 260 ELECTRICAL EXPERIMENTER August, 1918

Our Amateur Laboratory Contest is open to all readers, whether subscribers or not. The photos are judged for best arrangement and efficiency of the apparatus. To increase the interest of this department we make it a rule not to publish photos of apparatus unaccompanied by that of the owner. Dark photos preferred to light toned ones. We pay $3.00 prize each month for the best photo. Address the Editor, "With the Amateurs' Dept.

t "Amateur Electrical Laboratory" Contest t In this issue we publish some Interesting facts with excellent photos, describing One Amateur Electrician's experimental laboratory. Now "Bugs " -we want to publish a snappy one like it each month. Here's our proposition: Why not write up your "Electrical Lab.," In not more than 500 words. Dress It up with several good, clear photgraphs. If we think It good enough we will publish the article In display style and pay you well for It. The prize awarded to such articles will range from $3.00 to $10.00. And 'Bugs" - don't forget to make your article Interesting. Don't write -"I have a voltmeter, an ammeter, a switchboard," etc., ad infinitum. For the love of Pete put some punch in iti Tell us what you do with your instruments and apparatus. You don't mean to tell us that every Experimenter does exactly the same thing. "We know different -but from the general run of such articles which we have received in the past, one would naturally think every "Lab." made in the same mould. Remember-send a photo of YOURSELF along. Typewritten articles preferred. THIS MONTH'S $3.00 PRIZE WINNER -ELMER HUTCHINSON MOST fellows do not realize the fun in having an experimental laboratory. I am in partnership with Wilbert Hartle, who lives near by. I firmly believe in partnership of two boys as one may have one thing while the other will have something else of value. Our laboratory measures about fifteen feet by fifteen feet. We have just enough room altho as we are purchasing and making apparatus constantly we are soon going to be somewhat crowded. On one side are a chemical laboratory and a desk (Fig. 1). We use the desk for correspondence, studying and drawing. In the drawers we keep magazines and catalogs. We have about three years straight of the ELECTRICAL EXPERIMENTER. Fig. I shows the arrangement of chemicals. We have a compound of almost every metal and salt and can therefore make any chemicals we need. We learned analysis by having one of us mixing up something for the other to analyze. On one side is a work bench extending almost to both ends of the shop. We have a full equipment of tools for wood work, wood and metal turning, forging, foundry work, drawing and pipe fitting. The box on the lower right hand side of bench (Fig. 4) is a cabinet for holding nails, screws, tacks, bolts, and small "junk." We made the switchboard and have used it very successfully. An electric motor runs the shafting and machinery. We installed all the shafts and countershafts ourselves and connected up the screw-cutting lathe as shown in Fig. 3. We have found this lathe very handy for turning small paru of apparatus. The small lathe (Fig. 4) is not in use at present, but as soon as we get enough time, money and room we will set it up. The grinding wheel and dynamo are connected to the same line shaft. The drill press is not run by the motor because it is used for work that is too heavy for the motor. The pictures do not show much of the electrical apparatus among which are motors, an electric furnace, dynamo, step -up and step -down transformers, condensers, batteries, meters, etc. We have a complete "dismantled" wireless outfit. We have many books, such as a complete set of "Hawkins Electric Guides," besides chemical, physical, drawing, astronomy and mechanical books. and many I. C. S. hand-hnnks. We learn more from our laboratory than we do from any school or books.-Elmer Hutchinson. Yee

Views of Excellent Electrloal Laboratory. Owned and Operated by Elmer Hutchinson and Wilbert Hartle. I -The Chemical "Lab." Corns Where Hundreds of Metals emit Salts Are Carefully Stored le Glass Stoppered Bottles. 2 -A Part of the Laboratory Tool Equipment and a Caner of the Switchboard. 3- "Our Lathe" -a Vary Essen- tial Luxury In Every Well -Ap- pointed Experimental Electrical Laboratory. 4-This Corner Contains the "Lab." Desk. Book and Magazine Collection: Also a Drill Press and the Electric Motor Driving the Line Shaft"-Get That -Fellow Bugs-LINE SHAFT!! This Is a Regular "Lab. " -What?

www.americanradiohistory.com August, 1918 ELECTRICAL EXPERIMENTER 261 Phoney Patents Under this heading are puhlisht electrical or mechanical Ideas which you haven't a smell of a Patent yet. After they have allowed the Pat- our clever Inventors, for reasons heat known to themselves, have as yet ent, you must pay another $20.00 as a final fee. flat's $40.001 WE not patented. We furthermore cali attention to our celebrated Phoney PAY YOU $3.00 and grant you a Phoney Patent In the bargain, so you Patent Office for the relief of all suffering daffy inventors in this country save $43.00II When sending in your Phoney Pa ppllcatlon, as well as for the entire universe. be sure that it Is as daffy as a lovesick hat. The daffier the better. We are revolutionizing the Patent husiness and OFFER YOU THREE Simple sketches and short descriptions will help our staff of Phoney DOLLARS ($3.00) FOR THE BEST PATENT, If you take your Phoney Patent Examiners to issue a Phoney Patent on your Invention in Patent to Washington, they charge you $20.00 for the Initial fee and then jiffy.

SHOCK ABSORBERS OR STARTER

Prize Winner: JACKASSOMOBI LE. Now that the price of gasoline has soared so high that only aeroplanes can follow its skyward rise, my new Jackassomobile will come as a boon to all gas -weary autoists. Jackass runs on endless tread in mad endeavor to eat his oats. Endless belt drives dynamo charging storage batteries. The latter, run the 60 H.P. high -speed motor which propels auto. Surplus Juice feeds electric headlights, also the Jackass electric spark accelerator, to urge on the Jackass, should he become a speed slacker. Inventor, Julius Lantz, Maywood, Ill.

.. ,......

AUTO -TROLLEY. In order to conserve our I running coal supply propose to equip all trolleycars thruout the land with spring bellows along the -board as well as under every seat. Passengers boarding car then pump air into comprest air tank. When sitting down passengers also do likewise, and furthermore more air will be pumped Into tank pneumatic every time they are bounced up and down. Comprest air not only works brakes but runs the car and the surplus power runs a dynamo which pumps Juice thru trolley wire Into power house. Hence power house needs no coal at all. Inventor, E. Paul Gangewere, Chattanooga, Tenn.

www.americanradiohistory.com 262 ELECTRICAL EXPERIMENTER August, 1918

The "Oracle" is for the sole benefit of all electrical experimenters. Questions will be answered here for the benefit of all, but only matter of sufficient interest will be, publlaht. Rules under which questions will be answered: 1. Only three questions can be submitted to be answered. 2. Only one side of sheet to be written on; matter must be typewritten or else written In ink, no penciled matter considered. 3. Sketches, diagrams, etc., must be on separate sheets. Questions addrest to this department cannot be answered by mail free of charge. 4. If a quick 'answer is desired by mail, a nominal charge of 25 cents is made for each question. If the questions entail considerable research work or Intricate calculations a special rate will be charged. Correspondents will be informed as to the fee before such questions are answered.

ELECTRIC FAN PROBLEM. AERIAL TORPEDO. Your idea of releasing several of the (940) Arthur A. Everts Cu., Dallas, aerial torpedos so as to have them strike Tex., inquire: (942) Mr. A. Fiocco, Allentown, Pa., the in writes that: water the path of an on- coming U- Q 1. We have a large electric fan about boat torpedo is nothing new, as this scheme eight feet above the entrance to our store, Q. 1. He has been working upon an was proposed already last year by Mr. H. directly at the door, which gives small re- aerial torpedo and wishes our advice on its Gernsback. In an article in this journal sults. This is a large four -blade fan. We practicability. was described a new form of motor -torpedo, realize that many customers are kept out A. 1. Relative to your Aerial Torpedo, a number of which were to be carried along quite possibly this may find a practical appli- on each merchant vessel. cation in future military and naval opera- A number of inventors have worked on tions, but at the present time, or at least to the scheme of aerial torpedoes to be con- put it in another way, we would say that trolled by wireless or other automatic and the efforts made by various inventors along self -contained mechanisms, but up to this this line, up to the present, have not been time these ideas have not proven particular- very promising. ly successful, so far as we are aware. It might pay you, however, to work along the lines of a radio controlled aerial tor- §1l9GIï161tlA1I 117tC19111101101 11111} 1MMIN ^t9W!ISINi'MIIMI1PP ISIOfIIC pedo, or one that could be accurately controlled ODD PHOTOS WANTED AT by some other means. $1.00 EACH ! ! ! 110 VOLT D. C. BATTERY Now is the time to make your CHARGING. Files May Be Kept from Entering Store Kodak pay itself in a real praeti- (943) W. H. Jackson, Doors by Properly Placing Electric Fans as for New York, N. Y., Shown at "A' or "B," to Create a Constant - cal way. We are after interesting asks: Draft In the Doorway. photographs of out -of-the- ordinary Q. 1. What size resistance to use in electrical, radio and scientific sub - charging small storage batteries from 110 of our store thru the necessity of opening jects and are willing to pay $1.00 cash volt D. C. service. a screen door, which we must use in con- for every one we can use. Please A. 1. The amount of wire for a resist- junction with the present fan. Would one bear in mind that for half-tone re- ance to be used directly in the 110 volt D. of unusual power do the work? production in a magazine, a photo- C. line for charging storage batteries is as A 1. There is only one other way that graph should be particularly sharp follows: you can combat the fly nuisance, and that is and clear. Of course, if a subject Use 250 feet of No. 18 German silver by mounting several fans as shown in our a happens to interest us particularly resistance wire, connected as shown. diagram "A." In this manner, the fans well, we can have the photo retouched. will always blow towards the entrance and For the general run of subjects, how- if you can arrange the fans in such a way = ever, it does not pay to go to such that all the space is covered by them; in I expense. Therefore, please take pains other words that no part of the entrance to properly focus and expose your is without a certain amount of draft due to pictures. It often happens that a the fans, then in that case we are quite really mediocre subject well photo- certain no flies will enter. graphed wins approval over an ex- If the door is quite large it has been cellent subject poorly photographed. found that by putting a fan directly above 3 And don't send us plate or film "nega- the entrance as shown in sketch "B," that fives"; send unmounted or mounted this will prevent flies from entering the 3 "prints," preferably a light and dark shop. However, the fan in this instance one. would have to be quite powerful, say a 16" As to what to photograph: Well, fan. 3 that's hard for us to say. We leave that up to you, and every reader now MAGNETIZING STEEL BAR. z has the opportunity to become a re- Storage Batteries Can Be Successfully porter of the latest things in the realm Charged by Tapping off at the Proper Points (941) J. C. Miller, Caney, Kan., writes Along a Resistance Coll, Connected to a the Oracle: 3 of Electricity, Radio and Science. Direct- Current Circuit In this Manner. Q 1. That he has trouble in magnetizing 3 But, please remember -it's the "odd, a steel bar. novel or practical stunts" that we are interested in. Every photo submitted DOES A DYNAMO "PRODUCE" A. 1. From your description we con- ELECTRICITY. ceive that the trouble with your electro- should be accompanied by a brief de- magnet is that it is not powerful enough to scription of 100 to 150 words. Give (944) Richard Bohannon, Boonville, produce the results you desire. We ad- 3 the "facts" -don't worry about the Ind., asks: vise using a stronger magnetizing electro- t style. We'll attend to that. Enclose Q. 1. Does a dynamo produce electricity magnet, and offer the following pointer in stamps if photos are to be returned from the air? regard to magnetizing steel permanently. w and place a piece of cardboard in the A. 1. As to the original source of energy When the steel bar is placed over the a envelope with them to prevent muti- as developed in the dynamo, this is a poles of the electromagnet, you should cation. Look around your town and rather mooted question even among the gently tap the steel. This is done so as 3 see what you can find that's interest - best engineers of today. It is generally to shake up the molecules of the steel, and ing. considered that the dynamo does not pro- to cause them to set themselves all in the Address photos to- Editor "Odd duce electrical energy in the usual sense of same direction. If you will adhere to the Photos," ELECTRICAL EXPERIMENTER, the word, as the first law of physics states above, we are sure you will meet with suc- 233 Fulton Street, New York City. that energy cannot be produced- neither

cess. aIfMIIIAIQIIIlßgM9pIIpIMOYINPpp@MlEIMIIMIIIDIIMgMIMYiI1MfIlIOMIMMi (Continued on page 264)

www.americanradiohistory.com August, 1918 ELECTRICAL EXPERIMENTER 263

"You Get The Job" "We've been watching you, young man. We know you're made of the stuff that wins. The man that cares enough about his future to study an I. C. S. course in his spare time is the kind we want in this company's responsible positions. You're getting your promotion on what you know, and I wish we had more like you." The boss can't take chances. When he has a responsible job to fill, he_picks a man trained to hold it. He's watching you right now, hoping you'll be ready when your opportunity comes. The thing for you to do is to start today and train yourself to do some one thing better than others. You can do it in spare time through the International Corre- spondence Schools. No matter where you live, if you can be reached by the mails, the I. C. S. will come to you. No matter how humble or important your present position. I. C. S. training will help you go higher. No matter what your chosen work may be, some of the 280 practical I. C. S. home -study courses will suit your needs. Some Facts about the I. C. S. Choose Your Career the World's Largest School Do you like Electrical Work? Mechanical Engineering? Many of the The first student was enrolled in the Inter- foremost Electrical and Mechanical Engineers in this Country were I. C. S. national Correspondence Schools on October trained. Civil Engineering? _ ,t _ - 16, 1891. Thousands of Engineers n OUT cac _ - - - Today the records of the Schools show an were - - - - - enrolment of over two million. enabled to pass their examina -1 INTERNATIONALCORRESPONDENCErE SCHOOLS This is over six times greater than the total tion by the I. C. S. Civil En- I BOX 5389 SCRANTON. PA. obligating me. ho y I can quality for the post- of Harvard in the 278 years since I Explain, without enrolment gineering Course. Ship Draft- before I mark X. its organization. ! on, or In the subject, 'high mg? Bridge Engiveering? ELECTRICAL ENGINEER CHEMICAL ENGINEER It is over ten times greater than the total Electrician SALESMANSHIP of Yale since its doors swung open Architecture? C h e m i s- I Electric Wiring ADVERTISING MAN enrolment Window Trimmer in 1701. try? Hundreds of thousands I Eiectfc Lightin Electric Car Running Show Card Writer It is over five times the total enrolment of men have climbed into big Heavy Electric Traction Outdoor Sign Painter of all colleges, universities and technical jobs in the technical profes- Electrical Draftsman RAILROADER schools in the United States combined. Electric Machine Designer ILLUSTRATOR sions through I. C. S. help. I Telegraph Expert DESIGNER Stand the members of this army equidistant Practical Telephony BOOKKEEPER and their call passed from lip to lip would Accounting? Commercial MECHANICAL ENGINEER Stenographer and Typist Draftsman Cert. Public Accountant story of the I. C. S. ringing around Law? All over America, 1 Mechanical send the Machine Shop Practice Traffic Management the world. Chief Clerks, Private Secre- Gas Engineer Commercial Law 300 to 500 students each month report ad- I d alL ENGINEER GOOD ENGLISH taries, Accountants, gook- Surveying and Mapping Common School Subject. vancement or salary increases as a result of SERVICE keepers, Office Managers are I MINE FOREMAN Oa ENGINEER CIVIL the I. C. S. training. Reports of 1,000 typical STATIONARY ENGINEER Railway Mail Clerk students show that at the time of enrolment reaping the rewards of train- ARCHITECT Textile Overseer or Supt. their average wage was $53.90 per month. ing gained through I. C. S. Architectural Draftsman AORICCLTLRE At the time they most recently reported ad- PLUMBING AND IIEATING Navigator Spaalah spare -time study in these I Sheet Metal Worker Poulin liaising French vancement their average wage was $182.48 ATTOMOBILES Italian per month, an increase in earning power of subjects. Ship Draftsman $128.58 per month through I. C. S. Training. The first step these men took was to mark and mail Name Occupation What Others Have Done You Can Do this coupon. Make your start I Employer the same way -and make it Street right now. and No

, City State 17778 C You benefit by mentioning the "Electrical experimenter" when writing to advertisers. www.americanradiohistory.com 264 ELECTRICAL EXPERIMENTER August, 1918 THE ORACLE. (Continued front page 262) BOOK REM EWi # can it be destroyed. According to the latest Mesco Telegraph theories advanced by scientists, a dynamo simply acts as a converter or transformer, if we might so call it, in that it sets in Practice Set activity latent electrical forces which are always existent in the dynamo before the NAVAL ELECTRICIANS TEXT -BOOK, by Cap- For Learning Telegraph Codes armature is ever rotated. tain W. H. G. Bullard, U. S. Navy. Cloth In other words, the field magnet of the Bound. 1530 pages, 560 illustrations, price dynamo produces a magnet field which, as $10.00 net. Two volumes. Published by we now know is one form of electricity. U. S. Naval Institute, Annapolis, Md. with its numerous wires When the armature This set of two volumes forms really a corn - or inductors is rotated in this magnetic plete library for either those in the service or field, a conversion takes place, so that elec- civilian students, the extent of the work treated to develop and flow being very wide, and including both theory and tric currents are caused practise. The books are ably edited, and well along the armature inductors to the col- illustrated, with clear line cuts, diagrams and lecting commutator mounted on the arma- photographs where necessary. the current Volume one covers the theoretical study of ture shaft and from which electricity, including radio -telegraphy, and treats passes out into the external circuit thru On such important topics as direct current, ma- suitable brushes, etc. chines, instruments, devices and apparatus, alter- The Practice Set comprises a regular tele- way, that the nating currents and circuits, storage and primary graph key, without circuit breaker, a special It might be said in a broad batteries, the theory of the generation of electro- high pitch buzzer, one cell Red Seal Dry static machine derives its electrical energy motive-force, dynamo construction, based on ex- Battery, and four feet of green silk covered the air, but it is not correct periments with dynamo electric machines, incan- cord. or charge from flexible a derives its apparent descent lamps, arc lamps, faults of generators and The key and buzzer are mounted on a to say that dynamo motors, telephones, principles of radio -telegraphy, highly finished wood base, and three nickel energy from the air. et cetera. plated binding posts are to connected that The second volume treats in a very thoro and the set may be used for five different purposes. easily understood manner, on the practical aspects List No. Price of the subject in hand and together with volume 342 Telegraph Practice Set, with Bat- EFFICIENCY OF DYNAMO. one forms a very valuable work of reference, tery and Cord $2.70 Bazino, North Benning- which should be in the library of every elec- Weighs 4 lbs. packed. (945) Chas. A. trician and engineer. Volume two deals with the Price does not include postage. ton, Vt., writes the Oracle: practical discussion of the parts of generators and con- ar Mms< article on the motors, including various wiring diagrams of Goadiodk s PradiseSeiim[eoingthe Q. 1. In Mr. Cohen's various and Gtttlnedal Tina[ and Wilde Codes I nections, showing the types of speed con- MESCO testing of small motors and dynamos, trollers and starting resistances used on board fail to see how he obtains an efficiency of U. S. war -ships, and the reviewer does not hesi- I figured it as 4.02%. tate to mention that the "land lubber" will have 40.2 %; his eyes open when he starts to peruse these ex- A. 1. - Relative to Mr. Samuel Cohen's cellent books, for they abound with a great wealth article on the "Testing of Small Electric of valuable diagrams and hook -ups of motors and and Dynamos" in a recent number controllers, together with various simple, yet not Motors ordinarily very well understood, signaling appa- of the ELECTRICAL EXPERIMENTER, we would ratus, et cetera. advise that the efficiency in the example Some of the sections included in volume two on is 40.2% as he states, and not practical work, are: Service generators, service there cited motors, motor starting and controlling devices, 4.02% as your figures show. This is so for application of motors, motive power for generators by 373 This outfit Is the only reliable Instrument which will the reason that 150 watts divided switchboards and distribution panels, wires and enable students to become proficient operators in the watts equal .402, and this value must be wiring, electrical interior communications care of D. S. Naval Service, because it la equipped with a electne plant and accessories, et cetera, These vol- buzzer and miniature lamp enabling the user to multiplied by 100 in order to give the re- umes cover all of the latest electrical apparatus master both the visual and audible signals quickly. we therefore have List No. 52- Practice Set with Red Seal Bat- sult in per cent, and found on board naval ships, including the Sperry tery and Cord... $3.60 gyroscopic compass, and to those interested in this 40.2 %r. particular subject, these books are alone worth Weighs 4 lbs. packed. Price does not include postage. their price. Send for the New Edition of ELECTROLYTIC DECOMPOSITION OF WATER PIPES. ELECTRIC TRACTION, by A. T. Dover. 667 pages. Cloth bound, 518 illustrations, Our Catalog W28 W. W. Brinckerhoff, Mt. Vernon, it is pocket size. contains 248 pages, with over 1.000 (946) 5 folding plates, size 6 x 9 inches. Pub- illustrations, and describes In plain, clear language N. Y., writes: lishers, the Macmillan Co., New York, all about Bells. Push Buttons. Batteries. Telephone and Telegraph Material, Electric Toys. Burglar and Q. 1. Can electricity destroy water pipes 1917. Price $5.50. Fire Alarm Contrivances. Electric Call Bells. Electric in the ground due to leakage currents, etc.? A great stride in the advancement of a subject Alarm Clocks, Medical Batteries, Motor Boat Horns. the decomposition of that is of distinct moment at the present time has Electrically Heated Apparatus, Battery Connectors, A. 1. Regarding by the in this work on Switches. Battery Gauges, Wireless Telegraph in- to the effect been accomplisht author struments. ignition Supplies, etc. underground water pipes due Electrification of Railroads. Where such large of a considerable leakage of electric cur- demands are being made upon railroad facilities Send for the Catalog Now railroad tracks as you men- to ship supplies troops, etc., the present steam rent from the locomotives can bearly cope with the situation. tion, this is a frequent occurrence in cities Many noted engineers have maintained that, were Manhattan Electrical or other locations where there is liable to be all the roads electrified and coal conserved in this appreciable leakage of the electric cur- way, and all available water power used the work Supply Co., Inc. any accomplisht of the roads would be two -fold, besides NEW YORK: CHICAGO: ST. LOUIS: rent. a great saving of fuel which would prevent to a 17 Park Place 114 B. Wells St. 1108 Pins St. We would recommend that you look up great extent a recurrence of Dr. Garfield's famous San Francisco Office: 604 Mission St. matter in any book treating on modern "heatless" days. this Space does not permit to say all that is of electric railway practise at your local library value between the covers, but the following list in which you will find the present practise of chapters will enable the reader to realize the 110 V. Generators outlined for obviating or overcoming this importance of this volume. be Introduction -The Mechanics of Train Move- ONLY $5.00! difficulty. In general, there should not ment, Continuous Current Traction Motors, Single Holtzer -Cabot hand gen- such an excess leakage of electric current Phase Traction Motors, Polyphase Traction Motors, erators, while they last, from railroad tracks or trolley rails, that it The Testing of Traction Motors, The Control of $5.00. Order today. honey- Continuous -Current Tramway Motors, The Con- will cause water or other pipes to be trol of Continuous Current Railway Motors, the 110 -v. A. C. or D. C. In Motors, $8.50; D. C. Bat- combed and decomposed, often resulting Control of Single-Phase Railway Motors, The Con- tery- Charging Dynamos a dangerous condition or a burst water trol of Three Phase Railway Motors, The Contro) (or Motors) 24 -watt, 12 -v. main, but these cases happen right along. of Continuous -Current and Alternating Current 2 -amp.. $10.00; 75 -watt Motors for Regenerative Braking - Auxiliary Elec- (or 1/6 H. P. Motor) It is generally due to a high resistance joint trical Equipment for Tramcars, Auxiliary Electri- 30 -v. 21/2-amp., a series of high resistance joints in the cal Equipment for Electric Locomotives and Motor $15.00; or for Electric Tramways, 200 -watt (or 1 H. P. Motor) 20 -v. 10 -amp., $33.00; which may be caused by the fact that Coaches, Rolling Stock Water Motor rails, Electric Locomotives, Train Resistance, Track Con- 77 -watt 7 -v. 11 -amp. (like cut), $25.00; bonded at the joints and Dynamo complete 25 -v. 31 -amp., $16.00. they are not properly struction, Conductor Rails, Overhead Construction Order from this ad. Catalog FREE. between the rails. It has also been found on Railways and Tramways, Feeding and Distribu- Electric Co.,Dept-1S, Gas Bldg.,Cbicago the rails were of such high tion Systems for Tramways and Railways. Sub- Watson to occur where station Converting Machinery, Switchgear, etc. electrical resistance that they could not The book is profusely illustrated showing foreign carry properly the returned current to the and American applications, various types of loco- on Approval power house. It is often the case that to motives, switchboards, motor construction, etc., Shipped also complete diagrams for motor control, etc. Sev- r leamculazs o pmeut5 and my 4F. overcome this trouble, electrical cables are a w ttd dri,.s d demonstrate the fruti eral large are included showing constructional catatlog. Mente °rtunitr plates Fwa.Pass..34.7 H. P. ¡ `32x3;2 Crea W payUpe fui t eo [ run along parallel with the rails and con- details and wiring of standard electric locomotives. More cannot he said as the work must be seen Agensset nected to them at frequent intervals, and r. Shvmmtsiak and read to fully realize its great worth and it are prompt. Hoch in this way they safely and properly con- men, however remotely interested in harnessing cars guaranteed money hack. duct the returned current to the dynamos must needs find a ready demand from all electrical Adds reed . 115-In Wheelbase at the central station. electricity to the railroad problem. Data. agnHlon- Elect. Sta. & Loa. PPre r. D ept. Ble 16 (Continued on page 265) ROSS ROTOR COMPANY, Beab Temple, CLIeego, lmasls (Continued on page 265) You benefit by mentioning the "Electrical Experimenter" when uniting to advertisers. www.americanradiohistory.com 265 August. 1918 ELECTRICAL EXPERIMENTER

THE ORACLE. (Continued from page 264) The editor of this department recollects GET AHEAD THROUGH a case like this which happened in an East- when a large ern city several years ago, SYou 30 -inch water main, which was situated ELECTRICITY Tell BHow about 12 to 15 feet from the trolley rails, Let Terrell Croft, formerly of the had by electrolysis or leakage currents from Westinghouse Company, tell you the rails, become practically honeycombed where the current left the pipe line to re- I the secrets of success in electricity turn to the rails, and before the condition Learn electricity as you would in actual practice. Learn it of the pipe line was discovered, the pipe just like the highest paid electrical experts learned it. Do not burst one night, flooding the street and waste your time and money on amateurish or experimental books. surrounding cellars with several thousand You are out to win in electrical work, and want the facts about gallons of water before it was shut off. work as it is done, all plainly stated and clearly illustrated. The street had to be excavated all along You can understand how much easier it is to study and master the pipe line for about one block, and a this sort of books than the kind which are filled with technical new pipe installed. The city authorities terms, higher mathematics, and amateurish treatments. charged the trolley company with improp- erly maintaining their trolley rail system, Croft's NewLibrary of Practical Electricity and the traction company had to overhaul (Recently issued.) their entire trackage thruout the city. The Complete course, resistance of the rail joints when bonded 8 flexibly - bound is tested by means of a specially sensitive v o I s. - pocket millivolmeter periodically, in all well main- size-3000 pages tained traction and electrified railroad sys- - 2100 illustra- tems. tions. month if you're BOOK REVIEW. pleased. (Continued from opposite page) Zper DYKES AUTO AND GAS ENGINE EN- Never before in CYCLOPEDIA. Seventh Edition, 1918. the history of elec- Cloth bound, 916 pages ; size 10 x 7 inches. tricity has there Price $3.50. Publisht by A. L. Duke, St. been such a de- Louis, Mo. mand f o r trained Prohahly no better recommenr'ation of this hook electrical workers. can he given than that the Royal Flying Corps of England have sanctioned the hook and propose Whether young or using it for instructional purposes. old you cannot Each and every subject has heen carefully re. make a mistake by vised and brought up to date. For instance, under Carhuretion, the reader begins with the simplest taking up electrical form of the carburetor; after he becomes familiar work. It is a field in with the fundamental principles, he then learns the which you will always purpose and meaning of metering -pins, air -valves, have steady employment, dash -pots, and finally, the very latest Pitot or "plain- tube" principle, which is now becoming very and one in which the the reader or stu- popular. In just this manner, G£d. chances of advancement dent progresses from the first principle of an LIBRARY CBRAR1f LIBRARY LIBRARY s parts of a twelve cyl- are ever present. It is a engine to the complicated PF3DB litcnce kicnce fhACflfht field in which salaries inder engine. Esur The ignition suhject is made very simple and ZWff afC117QiT iLtiIWf11Y are unlimited. clear, as is also the subject of electric starting and generating systems by means of special drawings and photographs. c The repair subject deserves special mention. ó o. This Entire Every part of a car or engine is thoroly treated. One has hut to refer to the index to find out how

connecting rods, grind Nowt -. Library Sent to "take up" hearings, fltttAtpl Crtrtss Wu,tptG Wnisrs a. valves, test compression, and just what to do to Finnan Must STATIONS give an engine more power. Every detail is illus M..n iicgrmo- kW:8 is so that he 6tMaa oroi Free for trated and the explanation simple Ca74-r aórt áor has but to follow directions. m There are many new additions to the seventh edition, such subjects as Trucks, Tractors, Motor- Inspection cycles, Airplanes and Airplane Engines, are thor oly covered. NOT A Under the suhject of Trucks, not only the con- CORRESPONDENCE1COURSE struction,struetion care a d operation of a truck are ex- This is not a correspondence course. Each problem in electrical work m' made plain h wordso and figures.roes. plained, phut how to dis- assemble and repair a You consult the books themselves, and get your answer complete, instead of waiting y the mail s to truck engine is also explained. deliver the solution of your problems. These books are a complete unit, and supply you with a The Tractor suhject deals with different drive completed electrical education. When you master them you are ready to step into actual work methods, as "chain' and "rail- track" treads, trans. at a good salary. They answer the often -asked question, "Can I get all the information I need mission system, tractor engines, ignition, carhure- about electricity in one set of books'" tion, Holley kerosene vaporizer, air washers, etc. The Ford, "Twin-City," Caterpillar and Cleveland are used as examples. We Pay Transportation Charges Motorcycle subject treats on just those points We pay the charges on the books to you, and the return charges if you are not one wants to know about; how a twin "V" engine pleased. You are the judge. No arguments are offered to make you keep the fires, name of all parts, how the valves are open books. No agents are employed to bother you. ated and timed, how the magneto and electric Fill out the coupon now and let us prove to you that Croft's New Library McGraw -Hill system is operated, etc. The Indian and Harley- of Practical Electricity supplies you with the secrets of success in Davidson Motorcycles are fully explained and electricity. ,( Book Co., Inc" illustrated. U 239 W. 39th 'St.. Airplane engines are fully illustrated. Some of NEW YORK. the subjects are: types of airplanes, name of parta, Vol t- Practical Mathematics, 358 subject control memhers and instruments, showing their Contents: headings. Vols. a and 3- Practical Elec- Gentlemen: tricity, r too subject headings. Vol. Electrical location and purpose; how the airplane is made to y- Please ascend Machinery, typo subject headings. Vol. 5- Central send me the Library of and descend, how the landing is made, P r a c t i c a l Electricity (shipping principle of flight, glossary of aeronautical words Stations, Soo subject headings. Vol. 6- Wiring for Light and Power, t7ob subject headings. Vol. 7 charges prepaid) for to days' free ex- and terms. Then we find Airplane Engine con- amination. If satisfactory, I will $a struction, types of engines, how they differ from -Wiring of Finished Buildings, moo subject send automobile engines, cooling, lubrication, headings. Vol. 8- Practical Electrical Illumi- in ten days and 82 per month until $16 has carbure- nation, rood subject headings. been paid. If not wanted I will write you for tion ignition, valve timing, adjustments, etc. eturn shipping instructions. There is a dictionary of motoring terms, also an English -French dictionary of motoring words Name. and terms. Ford Supplement revised and im- McGraw -Hill proved. Packard Supplement in two colors, deal- Book Co., Horn Address ing with the 1918 model. Inc., City and State Inserts: -There are four large two-color inserts, No. 3 illustrates the Dixie Magneto with many 239 W. 39th St., Name of Employer large illustrations, showing all parts, their names His Address and purpose. Also the Dixie Motorcycle Magneto New York. and now it fires a twin -cylinder engine. The Indian Your Position Ex Aug. t8 and Harley-Davidson motorcycle engines are illus- You benefit by mentioning the "Electrical Experimenter" when writing to advertisers.

www.americanradiohistory.com 266 ELECTRICAL EXPERIMENTER August, 1918

trated with sectional views with all parts lettered; No. 4 is a large two -color illustration of a four - cylinder engine, especially adapted for class room use.

SOLDERING KINKS. Illustrated, 70 pages; paper covers ; size 6 x 9 inches. Publisht by The M. W. Dunton Co., Providence, R. I. Third Edition, 1917. Price 25 cents. An extremely interesting manual for the practical man containing a complete discourse on the art of soldering in all its branches. It tells the how, when and where: everything from the care of the iron to the proper fire, cleansing of joints, flux, etc. A large number of handy "kinks" are illustrated and described, some from practical experience of those who have actually accomplisht stunts as noted and others from experiments, etc. Some of the more difficult work is illustrated so that there may be no slip -up when doing the actual work. As an all around hand -book for the amateur electrical man, this work is sure to find a host of interested readers be they practical men or just plain, everyday Experimenters.

Group of Students in Corner of Dynamo Testing Laboratory -Practical Training RADIODYNAMICS, by B. F. Miessner. Cloth bound, 211 pages; 112 illustrations; size, 5/ x 8% inches. Publisht by D. Making Electrical Men Van Nostrand Co., New York. Price, $2.00. RADUATES of SCHOOL OF ENGINEERING G OF MILWAUKEE SUCCEED because they are The author, who is well known among the radio prepared in accordance with the requirements of fraternity, has brought forth a book of high - the great electrical world. They possess the necessary To Order sounding title at least, and one which should prove knowledge and practical ability to perform the functions of interest to those working along the lines of of the Electrician, the Electrical Engineer or Experts in radio-controlled apparatus. the various Electrical Trades. They are capable 0/ occupying the big positions electricity affords. They Its chapters cover every point from the first obtain the recognition that begets success and the high saltines ability commands. effort in this direction to the more successful latter -day attempts of John Hays Hammond, Jr. If You Enroll Here You Are Sure To Succeed It has been written in such a manner as to be equally interesting to the layman and scientific This school, from its fourteen years' experience and educational and industrial analysis, knows the require- reader, without sacrificing the technical matter ments for the young man entering the great field of electricity. As a result its faculty, text books, lec- valuable to the trained engineer. tures, laboratory and work -shop experiments and practice are selected to develop students to become the The following few section heads give a very practical electrical men of the requiren ability -which insures greatest success. This school is the connect- good outline of what has been covered in this ing link between the ambitious young man and the high salaried, electrical positions offered. Students volume: Historical and Practical Applications of are instructed, trained and developed here in the way the electrical industries want them - Electrical Men Wireless Telegraphy, Electro-Static Telegraphy, are blade to Order litre. Therefore, select this school and be sure of success. Come where you know Electro -Magnetic Wave System, Sound Waves you will obtain the education you need, to succeed. Save time and money-and avoid mistake. Obtain (with some very interesting data on Prof. R. A. all the advantages of a required electrical education and training -all the advantages this school affords. Fessenden's submarine signalling apparatus) infra. Decide to enroll here now -clip and mail the coupon at the left and secure new interestingly illustrated Red and Ultra- Violet Waves. Hertzian Waves, prospectus. The Advent of Wireless-Controlled Torpedoes,

with a discussion of Dr. Nikola Tesla s Tel - SCHOOL OF ENGINEERING OF MILWAUKEE automaton -the first radio -dynamic boat; also Rob. BUILDING ert's wirelessly directed airship. Various types of TWO BUILDINGS- INSURANCE BUILDING -STROH INDUSTRIAL selectors, relays, coherers and detectors are ex- MILWAUKEE, WIS. plained, with interesting notes on the application of the Audion as a relay and indicating instru- A THIS COUPON -AND MAIL NOW ment. complete chapter is devoted to the won- CLIP Your Other derful work accomplisht by Hammond in this field, 55.373 Broadway, Milwaukee, Wis. which all inventors and radio men will find deeply SCHOOL OF ENGINEERING interesting. OF MILWAUKEE Advantages Here Taken all in all, it's a highly interesting work, Without obligating nie in any way, please send me even tho it does not cover the details and systems your new prospectus, complete particulars regarding your and the following courses: WB ATET} R your past education. you can that one might infer from its ambitious title. It Institution, enroll here with your success assured. would seem that much of matter presented (CHECK COURSES INTERESTED IN) All branches of electricity taught in a the ....Electrical Engineering Courte, 3 yrs. Practical, thorough way. Twenty-four prac- especially that describing proposed detectors and' ....War Time Electrical Engineering Course. 2 yes. tical instructors. Ten departments. All mod- might have been substituted by a little more ....Complete Electrician Course -D. C. & A. C., I yr. em Instruments, tools, appliances, apparatus practical explanation of such radio control systems SPECIAL SHORT COURSES and machines. as have been found workable, at least to a reason- ....Electric Trouble and Linemen. You can 'ttam While You Learn" if you able extent. In other words, there is too much ....Electric Motormen. like. You will be given a splendid position mooted theory and not enough practise given. ....Electric Motor Repairmen. when you graduate. ....Electric Wiremen. R.S. and E.E. degrees given In three years. . ..Telephone Trouble and Repairmen. All the advantages other schools offer ....Draftsman. many advantages other school. are without.- PRACTICAL ELECTRIC ILLUMINA- NAME TION, by Terrell Croft. First edition, Mail That Coupon NOW! 225 pages; fully illustrated ; cloth bound; ADDRESS size, 534 x 8/ inches. McGraw -Hilt Book Co., New York, publishers, 1917. Price, $2.00. The author must be credited for the great field he has covered in this work. Every phase of illumination has been covered carefully, with much attention to detail. It should prove of distinct value to illumination engineers in general and much matter contained will also be useful to electrical engineers, contractors, students and electricians. The first section is devoted to explanations and Learn-Wireless Zèlegrapliy illustrations of the fundamental ideas of Light Radiation, The Velocity and Vibrations of Light, 40,000 wireless operators urgently needed for Army, Navy and etc. which are all intelligently shown and de- Aviation Service. Excellent opportunities to win promotion to scribed. commissioned and non -commissioned grades with advanced pay. A The practical applications of light cover the chance to serve your country in a "preferred" position. Work main text of the work, including data on correct I ., :_ll. trains you for position as Commercial Operator after the war j di S reflectors for various needs. All types of lamps with pay up to $200.00 a month. are described and illustrated -Incandescent, Arc, Nernst, Mercury -Vapor Tube, etcetera -showing Complete Course by Mail in 10 WEEKS the adaption of these various forms to industrial, Prepare now to enlist with better rank and pay. Start studying vQ residential, street and window lighting. at once in spare time at home. No previous training or knowl- The rinciples of Illumination Design are covered a, edge of electricity needed; a few weeks home -study of our in a clear and interesting manner, as well as the course will qualify you. Complete practice apparatus sent with design and installation of Interior and Exterior t Brat lessons. We help you enter any branch of Radio service you select. Illumination with examples and illustrations cover- Write at ing almost every conceivable application in use once for full particulars. Don't delay -a postal will do. today. A work which is very thoro, technically correct, National Radio Institute, Dept. 48, Washington, D. C. and complete. It will appeal to all those interested in the subject of correct illumination. Voss benefit by mentioning the "Electrical Experimenter" when writing to advertisers.

www.americanradiohistory.com August, 1918 ELECTRICAL EXPERIMENTER 267

A GIGANTIC EXPOSITION AND the grounds and rising to a height of 65 AMUSEMENT PARK IN THE feet, all a- glitter both day and night with MAKING. 10,000 cut glass jewels from the San Fran- cisco Exposition. In back of each jewel (Continued from page 222) will be a miniature lamp and when the switch is turned on in the evening, a plant and filters have a daily combined ca- splendor of radiance will shine forth sec- pacity for handling nigh onto 3,000,000 gal- ond to none. The Exposition period each lons. year will extend from May 30 to No- A ride which will attract thousands will vember 1. be the greatest scenic railway ever constructed, and a spectacular novelty will be "Creation of the World." SURVIVES 11,000 -VOLT ELECTRIC An exhibit known as "No Man's Land" SHOCK. will consist of practical working trenches îf under the command of wounded allied sol- Horace R. Williams, manager of the diers, and the construction will be super- Stevens County Power and Light Company Instruction by vised by a regular officer of the United of Colville, Wash., received a current of correspondence is the States army, the construction work being 11,000 volts at the power plant at Meyers andbestway done by soldiers who have lived amid these Falls and emerged with only three burns cheapest crude surroundings at the battlefront of in addition to the shock. for the poor man Europe. While insulating the Kettle Falls wires "No Man's Land" will occupy a space at the power house he came in contact with approximately three hundred by one hun- an exposed part of the wires. Both hands 1 dred and fifty. received the shock of the current, which escaped toward a bunch of keys in his pocket Another amusement feature will doubt- Edison is Right ! ! ! and burned his leg, emerging from the body You admit the International Correspond- less attract a great deal of interest, which at the point where the keys made a contact will be a model Congo farm, upon which ence Schools are a good thing. You'd take with adjacent metal. His hands were right now "except " all of the workmen are monkeys, apes, severely burned. a course "if"- - baboons, chimpanzees, etc., which have been "If" what? If you weren't so "over- educated to work with miniature tractor A physician drest the burns a few hours worked," with such "long hours," or had plows, hoes, spades and other garden im- later and the victim then went to his office. more strength and energy? plements, and which was inspired by the Few persons have survived such an experi- Wasn't it Edison who stayed up half the Government's plea for more farm labor to ence. His rubber -soled shoes, it is said, night educating himself in spite of every help round out the country's crops. saved him from the full force of the current. handicap you could ever have? All big men who have made their mark in Still another feature will be the large the world had the ambition -the determina- convention hall for the benefit of visiting tion-to improve their spare time, to train organizations which may wish to hold busi- themselves for big work. You, too, can pos- ness or social sessions to the exclusion of DR. CALDWELL DIES FROM sess power, money and happiness if you'll the general populace. X -RAY BURNS. only make the effort. Last, but not least, amongst all these Here sallweask: Merely mail thiscoupon. Dr. Eugene Wilson Caldwell, a noted Put it up to us without paying or promising. wonders, we find the largest carrousel in X -ray expert and the inventor of many de- the world, where big and small can ride Let us send you the details of others' suc- vices which have developed this science, cess through the I. C. S. and then decide. to their hearts' delight on the galloping died in Roosevelt Hospital in New York horses, donkeys, pigs, mules and all the City recently as the result of burns he suf- Taan OUT Hxng rest of the menagerie. ------fered many years ago while making experi- INTERNATIONAL CORRESPONDENCE SCHOOLS Everything will be of the best and it is ments with the X -ray. Dr. Caldwell was BOX SCRANTON, PA.- 5390, estimated that on the day the gates open, a Major in the Medical Reserve Corps, and Capialn, without obllgsting me. how I can qualify for the an expenditure of three million dollars under the direction of Surgeon General poslttot . Or in the subject, before which i mark X. will be represented. Gorgas recently perfected a device for stere- ELECTRICAL ENGINEER CnER10AL ENGINEER Electrician SALESMANSHIP oscopic fluoroscopy adapted to war surgery. Electric Wiring ADVERTISING MAN The electrical effects are to be some- Electric righting Window Trimmer having been designed by From the commencement of his Dr. Electric Car Running Show Card Writer thing stupendous, career Heavy ElectricTraction Outdoor Sign Painter engineers of the General Electric Company Caldwell devoted much of his time to elec- Electrical Draftsman RAILROADER Elenlrie Machine Designer ILLUS TRATOR in conjunction with the chief electrical en- tricity, and, aside from regular medical Telegraph Expert DESIGNER gineer of the grounds, Mr. Frank C. Still- work, had long been interested in the physi- Practical Telephony BOOKKEEPER MECHANICAL ENGINEER Stenographer and Typht man. Pretty and subdued effects will be cal problems of the X-ray. He engaged in Mechanical Draftsman Cert. Pub. Accountant main a new type of lamp is experimental in Ship Draftsman Traffic Management the features and work telephoning to light- Machine Practice Commercial Law to be used to outline the buildings at night ships under the United States Lighthouse Ma glShhop (GOOD ENGLISH CIVIL ENGINEER Common Sebaol Sableet. that will not have a glaring light but will Establishment in 1894 and 1895, and from Surveying and Mapping CIVIL SERVICE serve to diffuse it. The crowning achieve- 1895 to 1897 he was an assistant in the engi- MINE FORER'N Olt ENOgl Railway Mail Clerk STATIONARY ENGINEER 'restlle Overseer or Supt. ment of the art will be in the stately neering department of the New York Tele- ARCHITECT AGRICULTURE "Tower of Jewels," erected in the center phone Arehlteetnral Draftsman Navigator Soanbh of Company. HEATING l'onitryliablag Trends Sheet Metal Worker Automobile, Italian

Name Present Occupation Street THE MAGNETIC STORM and No. City State (Continued from page 2.33) MEN WOMEN beyond repair, a child could see that. He no means be a coincidence. flung it away and went over to the next "Verfluchte Amerikaner", he said, "prob- GOVERNMENT REQUIRES nearest flyer. But the mechanic had al- ably a new Teufelmaschine of Edison!" ready located the trouble -in the magneto. But what would the Kommando say to RADIO OPERATORS Burnt out, too! this? Instantly he stiffened as he jumped Special concentrated courses by experienced teachers Von Unterrichter unutterably sick at into a waiting automobile, attached to the for both men and women heart, aimlessly wandered about the other airdrome. machines. In each case the result was the "Zum Kommando, schnell", he ordered the MACHINE GUNS same: Every magneto armature of the driver as he sank back into his seat. He it will mean eomething to you to prepare yourself fifteen flyers was burnt out, the wires must report this queer business to head- for Service. We have completely equipped school for setting up" instructtoa, (Brasted by experts In fused together, all insulation gone! quarters at once. The driver cranked the this line. Write for booklet. "Aber so 'was", muttered on Unter- engine, then cranked it some more. Pfut You can begin at any time. richter, looking about him helplessly. It pfut ... pfut ... spluttered the engine took fully five minutes before it filtered asthmatic -like, but it did not start. He Y. M. C. A. Radio School thru his thick Prussian skull that this dis- tried again. Same result. 145 E. 86th Street New York, N. Y. aster that overtook his "circus" could by (Continued on page 268) BEST RADIO SCHOOL IN NEW YORK

You benefit by mentioning the "Electrical Experimenter" when writing to advertisers. www.americanradiohistory.com 268 ELECTRICAL EXPERIMENTER August, 1918

"Donnerwetter nochmal", stormed the "Supremacy Baron vexed over the delay, "was ist denn jetzt los, why in thunder don't you start, Learn Aviation Mechanics in the air ?" Train yourself for the Aviation Service by availing yourself of the Preparatory you miserable dog But the engine would Ground Course in Aviation Mechanics, affording preparation prior to entering the Key to not start. The perplexed chauffeur climbed Government Ground School, covering aero-dynainics, aero- engines, rigging and into the seat of the old style car, which Lewis gunnery. Previous experience unnecessary. Victory!" still had its faithful spark coils, so neces- a'go- sary to tile ignition system. But the spark COMPIETE COURSE e i n n g course, eV6 WE ARE AVIATION taken in six weeks (three hours daily) or THE PIONEER SCHOOL coil refused to work, altho the storage bat- three weeks (six hours daily) tery was fully charged and all the connec- L'tf ,eX tions were right. Cautiously he pulled out Special Aero- Engine Course (weeks) $35 one of the spark coil units from its box. One look told the story. Wireless Course (thr; e) $25 Mum " Ausgebrannt, Herr Leutnant," he said weakly, for he had seen the burnt out mag- Write for our Illustrated Booklet "B " -"A Message Telephone Bryant era neto armatures a few minutes before. to You on Aviation" 110 -114 WEST 42d STREET, NEW YORK Von Unterrichter, with eyes almost popping out of his head, was struck absolutely speechless for half a minute. "Heiliger Strohsack", he muttered awe- struck, remembering his young sister's favorite expression, whenever something out of the ordinary happened to her. He finally collected himself sufficiently and jumped out of the car. "Zuni Telefon", he muttered to himself. He must report this uncanny occurrence at once to the Kommando. Not a second was to be lost. He at last understood that something momentous had happened. He made the airdrome on the run and tho it was only 200 yards away he surprised himself at the speed he made. Puffing volubly he arrived at the telephone. He gave the handle several quick turns, *grasped the receiver and simultaneously bellowed into the mouth- piece in front of him : "Hallo, hallo" ... but he went no further. The receiver flew from his ear, for there had been a loud clattering, rattling, ear- splitting noise in the instrument that almost burst his eardrum. He made a foolish grimace, as he held his ear with his hand. Cautiously he approached the receiver to within a few inches of his other ear and listened. All was quiet, not a sound. Me- chanically he unscrewed the receiver cap and looked at the two bobbins. They were charred and black. The telephone was dead. . . The instrument slipt from his hand and dangling by its red and purple cord went crashing against the wall of the airdrome, while von Unterrichter limply sank into a chair. Once more he got up and walked out. The ability to use any one of five differ- He must get into touch with his General at ent length carriages on one typewriter is all costs. This was becoming too serious. only one of several exclusive features of the Ah . . . he had it, the field telegraph. Fox Typewriter. There was one at the other end of the building. This particular feature enables an operator with one He went there as fast as his legs machine to do varied types of work. -correspondence, could carry him. He opened the door of of ordinary the little office but one look sufficed. The billing, the making of reports, any out the young man in work. The carriages can be changed in a moment, charge of the telegraph sat the operator doing it without the slightest trouble. dejected in a corner, a dumb expression in his ekes. Long purple sparks were playing Another remarkable feature of the FOX. -its ex- about the instruments on the table. A tremely effortless operation, -is a revelation to --- child could have seen that it was impossible new users. to either send or receive a telegram under Fox Typewriters are used in larger numbers such conditions. . . . Ah! an inspira- by Railroad telegraphers than any other type- tion.... writing machine. In no other class of work t "Dnijtiikopf", he muttered to himself, do typewriters receive harder use, and the -, -'p "Why didn't I think of it before. Die ability of the Fox to stand up year in and Funkenstation! Surely the wireless must year out under such trying conditions work! Ha, ha, there are no wires there at has put it in first place with these dis- least to burn out !" criminating users. The radio station was over a kilometer The Fox dealer in your locality will .1 *LA ' away. He knew it well, for he had flown be glad to place a machine on trial in over it a great many times. To get there your office. Should it happen that quick, that was the question. The Korn - there is no dealer in your immediate vicinity, write us direct and ice will make mando was at least eight kilometers to the easy for you to test out the Fox in your own office. rear, and he knew he could not make that distance on foot very quickly. Ah, yes, there was a horse somewhere around. The WRITER COMPA1N, All German telephones are magneto operated. pfI?S, MlCtìlG.AN To call Central you must turn the handle of the ringing magneto.

You benefit by mentioning the "Electrical Experimenter" when writing to advertisers.

www.americanradiohistory.com August, 1918 ELECTRICAL EXPERIMENTER 269 cavalry horse was located soon, and as the young airman walked hurriedly about, trou- bled as he was, he could not help noticing the listless attitude of every man he past. Men were whispering in a hushed manner, alarm was plainly written in their faces - the fear of the unknown. ' Von Unterrichter jumped on to his horse and galloped in the direction of the field radio station. It did not take him long to reach it, and long before he dismounted he could see the bright blue spark of the send - ing station. Gott sei Lob ", he uttered to himself as he jumped to the ground, "at least that's working." Note here the curious mechanism of the Prussian mind. A Prussian officer, the YOU VOLE imagin- most arrogant, distasteful creature ELEMENTS DYNAMOS able, is always the great brave hero when uiu,utlERS PRINCIPLES he knows that he is fighting with all the J91APn1ENTS CNLCULAfON METER DESIGN advantages on his side. As Heinrich Heine, `fUSI'dna'R MILS the poet, -himself a German -hater, -puts it : "The Germans have no self- respect. They are the only men in the world who, as private soldiers, will stand still while an officer kicks them or bespatters them with mud. They receive the mud with smiles and stand expectantly, cap in hand." -German sort of "honor" ANaa1CAa RICAN ANaA1CAN It is the Prussian nCaNmAL "CLINICAL "CNNiCAL "CIaeCAL that makes a Zabern affair possible, where Sann SAM" SOMATA SHAWN,/ a foul- mouthed young officer, with his sword, beats a helpless, crippled Alsatian cobbler insensible. A coward at heart, always ready to blaspheme his maker, when things go right, the Prussian quickly turns to his SEND NO MONEY German Gott, as soon as things go against him. USE THESE ELECTRICAL BOOKS SEVEN DAYS Heine, himself a German, and he ought AT OUR EXPENSE to know,-will tell you so. By merely filling in and mailing the coupon below 'you can get this complete set of the Now it so happened that von Unterrichter Cyclopedia of Applied Electricity on trial. Pay only small shipping charges when they had been an expert wireless man before the arrive. Use these books for seven full days before you make up your mind whether or war, and while he did not know a great not you want them. If you keep them, you may pay the special advertising price in easy deal about electricity, he well knew how to instalments of $2.00 a month. If you don't want them, you may send them back at our send and receive messages. expense and you won't be out a penny. He ran to the wagon which carried the mobile radio field apparatus and peremp- A MASSIVE ELECTRICAL LIBRARY -NOT HANDBOOKS torily ordered the operator in charge away. These seven splendid volumes contain all the knowledge you need in order to earn big money "Aber Herr Leutnant", expostulated the in the electrical field. They are not thin handbooks, but thick, encyclopedia -size volumes, rudely interrupted man, "I tell you " thus ... handsomely hound in half morocco leather, gold stamped. Each one measures 7 by 10 "Maul halten", thundered von Unter- inches, and is 2 inches thick. richter, with, which he sat down, clamping the operator's receivers on his own head. This big size permits the use of large and comprehensive illustrations, plates, diagrams, He prest the key impulsively, and noted etc. Over 3,000 cuts are contained in the Cyclopedia's 3,500 pages. with grim satisfaction that the loud blue The completeness of the Cyclopedia will be a revelation to you. spark crashed merrily in the not very up- Everything electrical is explained in plain, simple English Read These Subjects - Elements of EleMrldb- to -date spark gap. every technical point is made clear. Each volume is carefully Electricai Measurements -Underwriters' Re uire- As he sent out the call mechanically, he cross -indexed for instant reference. menta- Theory. Calcula- wondered vaguely what the matter could tion. Design and Con- For this sum insignificant eV-notion of Generators be with the government,. because it did not -an and Motors - Dynamo- even supply a modern, up -to Lösch-. 50c a Week one this wealth of electrical Electrical Machinery -date - Lighting Machinery funkenstrecke quenched spark gap for information is yours. But you don't have to send us a penny - Power Tranemitsion - - - until you have used the books for seven days. Then, if you EleoMc Ratlwaya-Power field use. Things must be pretty bad when Stations - Switchboards the government must economize even a few decide to keep them, send only $2.00 a month-50c a week. and Switching - Storage until the special advertising price $19.80 has Batteries--Applied Elec- beggarly pounds of brass, so necessary for of been paid. tro- Chemletry - Electric The regular price of these pay -raising books is $35.00. Elenmrs- ilectrio Weld- a noiseless spark gap. ing and Heating -Wire But he could not give that matter further and Wireless Telegraphy. attention for he had thrown the aerial Consulting Service Free switch from "sending" to "receiving." A year's Consulting Membership in the American Technical M .. M. t=I - Mr - - OR OM Society-regular pricerice 12.00 included He had strained his ears for a reply $ -will be with all or- American Technical Society from the operator from the Kommando, dens for a limited time. The advice of an entire corps of I Dept. E -744C. Chicago, U.S.A. but, as the switch was thrown, instead of electrical experts is yours to help you in your progress- Pléasesendmethe cyclopedia for a whole year FREE! Applied a reply there was a loud, constant roar in t dof Eltloncityfoorrlsevvenn the receivers, so loud that it was painful. No I net shipping charges. If I de- Off came the headgear, while von Unter- Send Money-Just the Coupon cide to buy, I will send you $2.00 richter once more sank into a chair. See these books for yourself before you buy. Remem- t sreavteen a y$s2 d t hme ncuntil the odf .an a obnatlha, He was a pitiful spectacle to look at, the ber, you don't risk a penny or assume a single ob- E19.80 has been paid. Then you fate of a 20th Century man flung back a ligation. The books will be sent to any one within will send me a receipt showing that the boundaries of the United States or Canada, the set of books and the $12.00 con- hundred years. His eyes roamed idly about * suiting membership they may be our expense are mine and fully till the distant railroad embankment struck and returned at if they t paid for. If I think that I can get along his eye. No train was moving. Everything fail to please. But you must act now ! This s without the books, I will return them generous offer cannot be continued indefinitely. t after seven days, at your expense. was at a standstill -how could a train move t without a telegraph? How could a train be Send the coupon now. t Name dispatched -there would be a thousand col- AMERICAN TECHNICAL lisions. He turned to radio SOCIETY ; the operator, E-744 C Address who as yet had not grasped the situation in Dept. CHICAGO, U.S.A. its entirety. / Reference You benefit by mentioning the "Electrical Experimenter' when writing to advertisers.

www.americanradiohistory.com 270 ELECTRICAL EXPERIMENTER August, 1918 "Nordlicht, nicht wahr, Herr Leutnant'" electric oscillator was so terrific that its no the phe- effect was felt 13 miles away. Altho there 80 to 100 30 Words he began, thinking doubt that Words a Minute- nomenon was an ordinary form of Aurora were no wires between your laboratory a Minute Hard Borealis, -the northern lights, -in other and the Colorado Electric Light & Power Blindfolded I Work l words, a magnetic storm, that would be Co., five miles distant, your "Wireless" over soon. Energy burnt out several armatures of the large dynamo generators, simply by long rDummes Rindsvieh" . , . snapt the Herr Leutnant, who knew better by this time. distance induction from your high frequency oscillator. You subsequently raised A Indeed he was to know still more at once, for while he was speaking there came to such havoc with the Lighting Company's his ear a low dull roar, a sound he had dynamos that you had to modify your ex- The New Way The Old Way periments, altho you were over five miles Speed of 30 to 40 heard once before, way back in 1914 when Speed of 80 to 100 the Germans had retreated very much in a away from the Lighting Company.* words a minute guar- words a minute. Fre- then, in 1898, twenty years ago, quent errors. Hard work. hurry beyond the Marne. "Now if anteed. Absolute accuracy. sal- Amazing use in typewrit- Keep stenographers' you could do that, why, WHY cannot we aries down to $8, $10 and Panic seized him. Yes the sound was un- ing. Hu increased salaries $15 a week. Anyone can go a step further in 1918, when we have at from $8, $10 and $15 a uickly change from the mistakable. The German army once more our command vastly more powerful gen- week to $25. $35 and Burn 8ld Way to the New Wq was in full retreat -no it was a rout -a Me a week. in le Easy Lessons. erators and better machinery. If you can panic -stricken rabble that made its way burn out dynamo armatures 13 miles dis- back. tant with a paltry 300 kilowatts, why can- Like lightning the news had spread among not we burn out every armature within a Typewrite the men at the front that uncanny things radius of 500 miles or more. were afoot, that all communications had "The primary coil of your oscillator in The New Way been annihilated with one stroke, that no 1898 was Si feet in diameter. WHY cannot Employers pay for the amount and quality of FINISHED orders could be sent or received except by we build a primary `coil' from the English WORK you turn out. Double or treble your typewriting efficiency and your salary will increase ht proportion. prehistoric couriers, that the Grosses Kom- Channel down to Switzerland, paralleling The NEW WAY L a revolutionary new method of saving mando was cut off from the army, and that the entire Western This is not such work and time and eliminating errors in typewriting. 80 to front' 100 words a minute GUARANTEED. Already thousands of in short the German army as far as com- a foolish, nor such a big undertaking as stenographers have so vastly INCREASED THEIR VALUE munication was concerned, had suddenly through the New Way. that their salaries have been in- you might think My calculations show creased to $25, $35 and even $40 a week. found itself a century back. that if we were to string highly insulated LEARN IT AT HOME; 10 EASY LESSONS For what had happened to von copper wires one -quarter inch thick on tele- Yes --only 10 easy lessons and this wonderful speed and Unter- accuracy In typewriting are YOURS. No interference with richter that morning, had happened on a graph poles behind the front, the problem you[ present work. Learn at home largely away from the would become a simple one. Ordinary tele- machine. Not like the old "touch" system. Hundreds of large scale not only to every one along the "touch" typewriters have doubled and trehled their speed front, but all over Germany as well! Every graph poles can be used, and each pole is to through the New Way. Based on GYMNASTIC Finger Training -an entirely new idea. Entire course on trial; nu train, every trolley car, every electric motor carry twenty wires. Beginning three feet met to you unless it brings the desired results. Write above the ground, each wire is spaced two postal today for full particulars. Read why the small cost or dynamo, every telephone, every tele- of the Course will quickly come back to you many times graph had been put out of commission. feet distant from the next one. These over. Address wires run continuous from the sea to 'The Tulioaa School, 3548 College Hill, Springfield, Ohio With one stroke Germany had been flung back into the days of Napoleon. Every Switzerland. Moreover, every ten miles or modern industry, every means ARE of traffic- YOU A MENTAL except horse -drawn vehicles -were at a The above occurrences as well as the cited standstill. experiments and effects of the Tesla currents are AND PHYSICAL WRECK? For days the German retire- actual facts checked by Mr. Tesla himself, who ment went on, till on the fifteenth day, the saw the proof of this story.- Editor. no you wake up each morning feel- ing that you've got to drag yourself entire German army had retired behind the through another day? Aching In every natural defenses of the Rhine, the victorious part of your body; no appetite, no energy; your brain full of cobwebs. Allies, pressing the fleeing hordes back ir- your nerves all on edge; tired out be- resistibly. fore you even begin your work? It means that SOMETHING'S WRONG that your heart. lungs. liver. And it must have been a bitter pill for stomach isn't working right; your food the German high command to swallow when isn't assimilating, nourishing you as it should; your circulation is out of they saw that the Allied fliers were con- gear; your blood Isn't building up your stantly flying behind own lines and wasted tissues it means that you ore their gradually going to pteoa. that as the Allies advanced, their automo- LET ME GIVE YOU VIM, VIGOR, VITALITY biles and their trains seemed to run as well with healerie he world-NATURE. I have tudied as ever behind their own lines. But no her eeerets: have learne the Tows which batring back health, strength, energy,a vital German succeeded in flying an aeroplane form. to weak, emaciated, memic carer or in running an automobile. That mys- 1 HAVE HELPED THOUSANDS terious force obviously was trained only your the of your Indiscretions. forget it. ok ahead of against the Huns, but was harmless behind back. Learn ou , can strengthennevery one of your vital the Allied lines. Nor did the Germans find organs. Learn how it will isayeerbene.anti, sh. rid of disagreeable. h art- out to this date what caused their undoing. PD e I V. c t D p y h art m moaclea, ability in brain, P. MT Punrh rant year Peace having not been declared as yet, I The pthousa d The man nun So -hap d Hf,T itwu=1an ilï a. R for thousand. more. book. Promotion and Conserva- 'cannot, of course, divulge the full details tion of Health, Strength and Mental Enema," tulle all about it. Sent FREE on receipt [ three 2e stamps cover mailing ex- of the scheme of just how the Germans tremes. Write ford today. were finally flung across the Rhine. That, LIONEL STRONGFORT of course, is a military secret. Physical and Health Specialist But I am permitted to give an outline of 596 Park Bldg. Newark, N. J. just what happened on that memorable a,.411.,. aiViZaral4 morning, when the German "Kultur" was flung back into the dark ages where it be- Who w ill write the longs. a

SONG-H ITHEWAR i But first we must go back to Tesla's laboratory once more, back to that evening With this country entering its second year in the "World War" it is doubtful it the song which will be when "Why" Sparks first overwhelmed known as the "Hit of the War." has as yet made its Tesla and his companions his appearance. While it Is true that such war Songs as with idea. "Over There" and "Liberty Bell" have made some im- This is in part what Sparks said: pression, have Our Boys adopted another 'It's A Long \Vay To Tipperary." which has been the great favorite "Mr. Tesla! In 1898 while you were with the English Tommies" Inasmuch as several making your now THIS BOOK COST $28,000 Commanders of our training cantonments have requested historic high-frequency boys in the service to write such a song, it appears to experiments in Colorado with your 300 - Over 1200 Authors Contributed be still wanting. Have you an idea which you think might be used as kilowatt generator, you obtained sparks 100 Contains a goldmine of electrical and scientific the subject for a Patriotic or War Song? If so, you feet in length. The noise of these sparks information. No such value has ever been offered may secure sonic valuable information and assistance by like before for so low a price. A marvelous cyclopedia of writing for a Free Copy of our new booklet entitled was a roaring Niagara, and these spark electricity. A reference book of authentic informa- "SONG WRITERS' MANUAL ANO GUIDE." We discharges were the largest and most won- tion not found in any other book to print. revise song -poems. compose and arrange music. secure Volume contains twelve of the "Eleetrloal Ex. sale. derful produced by numbers copyright and facilitate free publication or outright man down to this very perlmenter" magazine -May, 1917 to April, 1918, Inele- Poems submitted xamined FREE. day. The Primary coil of your oscillator sine. There are 928 pages, 2,110 complete artloles 1908 KNICKERBOCKER STUDIOS. 75 Gaiety Bldg., N. Y. C. Illustrations, 369 questions and anymore. Size, 12'/ high; measured 51 feet in diameter, while you 9" wide; Imo" thick. used 1100 amperes. The voltage probably Add BOOK ON AVIATION was over 20 million. Now, then in your $2aóo Postage Learn of the great opportunities in this new book, High Frequency Currents, among for 8lbs $1.000.000.000 industry. Thousands of men needed. Learn bymail -free book tell. how. W rite at once. other things you state that the current which NATIONAL AIRO INSTIMIE, Dept lea Nedes Bldg., Chime N. you produced by means of this mammoth [XP[RIM[NTfR PUB. CO., Inc., ns `alts üroflVial, You benefit by mentioning the "Electrical Experimenter" when writing to advertisers. www.americanradiohistory.com 271 August, I 9 I 8 ELECTRICAL EXPERIMENTER so we place a huge 3,000 kilowatt generating plant with its necessary spark gaps, ake All This Your 'Own Office - condensers, etc. The feed wires from these Come True Yd'ur Own Hoúr's generating plants then run into the thick wires, strung along the telegraph poles, forming the gigantic Tesla Primary Coil. Of course, you realize that in a scheme of this kind it is not necessary to run the telegraph poles actually parallel with every curve of the actual front. That would be a waste of material. But we will build our line along a huge flat curve which will sometimes come to within one -half mile of the front, and sometimes it will be as much as fifteen miles behind it. The total length of the line I estimate to be about 400 miles. That gives us 40 generating plants or a total power of 120,000 kilowatts/. A similar line is built along the Italian front, which is roughly one hundred miles long at present. That gives us another 30,000 kilowatts, bringing the total up to 150,000! Now then, the important part is to project the resultant force from this huge Tesla primary coil in one direction only, namely that facing our erstwhile friends, the Huns. Doctor of Chiropractic This I find can be readily accomplished by Advanced Science of Spinal Adjustment screening the wires on the telegraph poles at the side facing our way as well as by Here is your opportunity to prepare yourself to enter the profession of using certain impedance coils. The screen Chiropractic -the modern science of relieving ills and ailments through spinal is nothing else but ordinary thin wire net- adjustment. No matter where you live or what you are now doing, you can ting fastened on a support wire between enter this uncrowded profession -a profession of good incomes. Some of our the telegraph poles. This screen will then graduates report they are making $3,000 to $5,000 and more a year. We teach act as a sort of electric reflector. So." . you by mail or in class. Sparks demonstrated by means of one of his sketches. 22 Complete Charts "Everything completed we turn on the high -frequency current into our line from the sea to little Switzerland. Immediately E E in Drugless Healing we shoot billions of volts over Germany As an extra inducement to quickly secure new students we will give you, and Austria, penetrating every corner of absolutely) free, our 72 -page book and 8 Anatomical Charts, beautifully litho- the Central empires. Every closed coil of graphed in lifelike colors, that regularly sell for $15, wire thruout Germany and Austria, be it a also complete set of colored Nerve, Pain Area, Con- Our Lessons Teach You dynamo armature, or a telephone receiver cussion and otherCharts that regularly sell for $16.50. howto makeSpinal Adjust- coil, will be burnt out, due to the terrific Don't miss this liberal offer. Get these free charts ments for speedy relief of by all Headache Neuralgia electromotive force set up inductively to means. See how you may qualify as a Doctor Indigestion Neuritis our primary current. In other words every of Chiropractic and what splendid opportunities this Lumbago Catarrh profession offers you for gaining an independence. Epilepsy Fevers piece of electrical apparatus or machinery has Pleurisy Jaundice will become the secondary of our Tesla Never before the demand been so great for Doctors Constipation Dyspepsia coil, no matter where located. Moreover of Chiropractic. To meet this demand we must have Rheumatism Paralysis the current is to be turned on in the day more students immediately. Write today. Asthma Etc.. Etc. time only. It is switched off during the night. The night is made use of to advance Learn At Home To Be a the telegraph poles over the recaptured land,-new ones can be used with their huge primary coil wires, for I anticipate CHIROPRACTOR that the enemy must fall back. Turning off No special talent or advanced education necessary. If you have the power does not work to our disadvan- common school education, the way is open to you. This institu- tage, tion trains you either by mail or in class. Learn in your own CouponToday for it is unreasonable to suppose that home in your spare moments to be a Doctor of Chiropractic. It the Teutons will be able to wind and install offers you a profession of dignity and prestige. Let us prove new coils and armatures to replace all the how YOU can make a good income. Makes no difference where you live or what you do now, you should be able to FREE CHARTS millions that were burnt out during the qualify rapidly for this great work. AMERICAN UNIVERSITY, day. Such a thing is impossible. Besides, Manierre Bldg.. Dept. 271 Chicago once Gentlemen:- Without coat or obligatioa, send we get the Germans moving, it ought Mail Free Coupon at Once new to No obligation to you whatever. Put your name and ad- me by mail, your illustrated. 72 -page book be a simple matter to follow up our address on the free coupon or letter or postcard and get the ' and your Free Charts Oder. vantage, story of Chiropractic. You will he amazed, faacioated by for you must not forget that we the facts gathered together in our free hook. Be sore to will destroy ALL their electrical communi- write at once if you want the free charts. Mail the Name cations with one stroke. No aeroplane, no free coupon or a postal today. right NOW! AMERICAN UNIVERSITY Address automobile, will move thruout the e Central Mannierre Bldg. Dept. 271 Chi..ago States. In other words, we will create a , City titanic artificial Magnetic Storm such as the world has never seen. But its effect will be vastly greater and more disastrous than any tr THERE'S /TONEY /N /T " natural magnetic storm that ever visited this earth. Nor can the Germans safeguard -ÑOME- LEARN TELEGRAPHYE themselves against this electric storm any MORSE AND WIRELESS==_- more than our telegraph companies can when a real magnetic storm sweeps over the earth. Also, every German telegraph TEACH YOURS _,F or telegraph line in occupied France and la half the usual time. at trifling cost. with the Belgium will be our ally! These insulated wonderful Automatic Transmitter. THE OMNIOOAPH, metallic lines actually help us to "guide" Sends unlimited Morse or Continental messages. at our energy into the very heart of the any speed, just as an expert operator would. enemy's countries. The more lines, the Adopted by U. S. Gov't. 4 styles. Catalogue ires. better for us, because all lines act as feed wires for our high frequency electrical OMNICRAPH MFC. CO. torrents...." 39L Cortlandt St. New York

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www.americanradiohistory.com 272 ELECTRICAL EXPERIMENTER August, 1918

A few kilometers north of Nancy, in the Department of Meurthe et Moselle, there is a little town by the name of Nomeny. It is a progressive, thrifty little French town of chief importance principally for the reason that here for four years during the great war the French army has been nearer to the German frontier than at any other point, with the exception of that small portion of Alsace actually in the hands of the French. MELODIOUS Nomeny in the military sense is in the Toul Sector, which sector early in 1918 was REPRODUCER taken over by the Americans. If you hap- -the greatest improvement ever pened to go up in a captive balloon near made for reproducing music and Nomeny you the human voice. It is a big step could see the spires of the in advance of any other repro- Cathedral of Metz, the great German fort- ducing device. It eliminates all ress, but 16 kilometers away, always pre- that harsh, metallic scratch and suming that the air was clear and you had twang and reproduces the tones, a good glass. vocal or instrumental, in their On a recent warm summer morning there true beauty and individual value. were queer doings at a certain point in the The following letter, (one of hundreds) written by an enthusiastic user, outskirts of Nomeny. All of a sudden this expresses the opinion of thousands who have heard this wonderful device. point seemed to have become the center of interest of the entire French, British and Dear Mr. Ellis: I would be unappreciative indeed, if I did not give you some expression of my great American armies. Since dawn the military delight in listening to your Melodious Reproducer. autos of numerous high Allied officers had I have never heard the vocal numbers reproduced more beautifully. I never heard been arriving while the gray -blue uniforms Caruso reproduced as perfectly as with your Reproducer. It was, indeed, a delight to listen to the trios of the violin, harp and 'cello, as the melody of the French officers were forever mixing of each Instrument could easily be detected and the blending was perfect. In Melba's rendi- with the business -like khaki of the British tion of "Lo Here the Gentle Lark," the flute tones were beautifully realistic. and Americans. In reproducing some of the soprano arias, I observed that In the upper register your Reproducer "picked up" every tone with ease and smoothness, whereas with several makes of The visitors first gave their attention to talking machines I notice some of these tones are lost. Then, too, It was particularly pleasing the camouflaged, odd -looking telegraph to listen to the phonograph without being conscious of any scratch whatsoever, even in the poles which looked like huge harps, with pianissimo passages. Sincerely yours, the difference that the many wires were Name and address furnished upon application. running horizontally, the telegraph line stretching from one end of the horizon to Fits Any Machine the other. A few hundred yards back of The Ellis Melodious Reproducer plays perfectly all diets record selections and 1. adapted for all makes of phonographs and talking machines using disc records. this line there was an old brewery from Steel, fibre or any type of needles work perfectly. As the weight 1. less than four ounce.. records wear Indefinitely. which ran twenty thick wires, conecting Every reproducer Is fully guaranteed for b years. Write for circular No. 9. the brewery with the telegraph poles. To'. this brewery the high officers next strolled. J. H. ELLIS An inspection here revealed a ponderous Post Office Box No. 882 Milwaukee, Wis. 3,000 kilowatt generator purring almost si- lently. On its shining brass plate was the legend : "Made in U. S. A." There was also a huge wheel with large queer, round ÿß.i . laY .W.W.YYiY.W.WW.W.YY... fif:. Y.V.V. zinc pieces. Attached to the axis of this wheel was a big electric motor, but it was not running now. There were also dozens of huge glass jars on wooden racks lined CHARGE YOUR OWN: against the wall. Ponderous copper cables connected the jars with the huge wheel. .u, F =F BATTERY r One of the French officers, who previous ,, ,,,,uuuw,,,,,,,,,,;,,,,;, to the war had been an enthusiastic Wire- BOOSTER . less Amateur, was much interested in the x.37\7,1,96,----,4,0,,A FULL WAVE A. C. RECTIFIER huge wheel and the large glass bottles. } "Aha ", said he, turning to his questioning t. : -. __._ _.._._. % Be Your Own Service Station . American confrère, "l' éclateur rotatif et \\\ \\t\\\ a\ For Public or Private Use:a les bouteilles de Leyde." Tbls little machine is selling There ' like hot cakes end makes every was little satisfaction in this, but \. 1 \VAA ?. .rn purchaser smile his own Dwhy just then a red -haired, tousled young man -- - ' `\ \° Q ness eeeaeltu and wonder why \ \ he hadn't bought one before, who seemed to be much at home in the \ You simply attach it to the brewery, \,\ came over and adjusted something cents \\ cost foor current your battery is on the huge wheel. full of "pep. Buy now. : "What '\ We fumleh complete portable . do you call all of these do- charging Rheostat with ammeter funnies?"'our young officer asked of him, end current mr for lento, s- on D. C. circuits,circuits. pointing at the mysterious objects. MAGNETIC RECTIFIER PAT'D APR. 18,.1918 Complete, and up { "Rotary spark gap and Leyden jars," was $24 F. C. B. Cleveland .. the laconic reply. The officer nodded. Just Ask your dealer or fors : The France Manufacturing Co., Cleveland, O. t wife then there was a big commotion. The door flew open and a French rY.'.YSttitiYA WANYY1L.JLti M.W W.V.W.W.V. rY Y: ai Y officer standing at ' attention shouted impressively: "Le Président de la République!" You Need This Tool Instantly every man stood erect at at- Useful tention, hand at the cap. A few seconds The "RED DEVIL" Chain Drill will drill engine cylinders, sheet later and President Poincaré walked in steel, steel beams, wagon tires, safes, boilers, pipes, flanges, etc. It slowly, at his side General Pétain. It was can be used as a clamp. Works with a bit- brace, hand -drill, breast - then five minutes to 10. drill or even a wrench. President Poincaré was introduced to the red -haired, tousled young man whom The "RED DEVIL" Chain Drill he addrest as Monsieur Sparks. Monsieur has an automatic feed, adjustable to any pressure. It is practically a portable drill - Sparks speaking a much dilapidated press. Friction minimized by hardened tool -steel ball bearings and ball races. Thread French, managed, however, to explain to is machine-cut from the solid rod, not cast. Has 3 -ft. polished steel chain, extra lengths if required. Nickel-plated Universal Chuck holds round or square shank drills and bits his excellence all of the important ma- 3/16" to 3g ". Alligator jaws of forged tool-steel. chinery, thanks to a sleepless night with a If not at dealer's, send his name and $3.45. and we'll see you are supplied. French dictionary. Ask your dealer to show you other "RED DEVIL" Tools; Pliers, Monsieur Poincaré was much imprest Hack -Saws and Blades, Class -Cutters, Electrical Tools, etc. and visibly moved, when a French officer SMITH & HEMENWAY CO., Inc., 107 Coit St., Irvington, N. J. had gone over Sparks' ground, and re -explained the finer details. You benefit by mentioning the "Electrical E.rperimenter" when writing to advertisers.

www.americanradiohistory.com August, 1918 ELECTRICAL EXPERIMENTER 273

The President now takes his stand on an "Why, oh WHY, do they call you elevated platform near a huge switch which éclateur!" he says., "Spark Gap is good has an ebonite handle about a foot long. enough for me !" "Oh, boy I I But you He then addresses the distinguished assem- aren't doing a thing to those Germins!" bly with a short speech, all the while watch- THE END ing a dapper young French officer standing in hand. near him, chronometer Translation of German and French Somewhere a clock begins striking the Terms Used in This Story. hour of ten. The President still speaks but finishes a few seconds later. The dis- GERMAN tinguished assemblage applauds and cheers only to be stopt by the dapper Verdammte Yankee Schweinehunde: Damned Yan- vociferously, kee Pig -Dogs! young officer who slowly raises his right Sie, Müller: You Muller) hand, his eyes glued to the chronometer. Zu Befehl, Herr Leutnant: At your orders, Lieu. silence prevails, only interrupted tenant! Immediate Versammlung, sofort: Assembly, at once! by the soft purring of the huge generator. Dieses Amerikanische Gesindel: This American The dapper young officer suddenly sings rabble! Schiesst die Lumpen zusammen: Shoot the raga- Out: muffins together! "Monsieur le Président! A- ten -tion! Vorwärts fur Gott und Vaterland: Onward, for ALLEZ!!" God and Fatherland! Big Money m Electricity Dollarjäger: Dollar Chasers. The President of the glorious French Re- Elendige Schweinebande: Miserable hand of pigs. The electrical industries offer wonderful public then shouts dramatically: "Mes- Unsinn: Nonsense. Flieger: Flyer (aeroplane). opport. pities to boys with a liking for Elec- sieurs . le jour de gloire est arrivé . . , Himmelkreuzdonnerwetter: A popular German tricity. - The salaries paid to trained men are VIVE-LA- FRANCE!!" -and throws in cuss word. Literally it means "sky- cross- large, promotion comes rapidly and, best of the huge switch with its long ebonite han- thunder." English equivalent is "A thousand thunders." Ill, the work is fascinating. dle. Kaput: German slang, equivalent to our slang The discovery and development of new Instantly the ponderous rotary spark gap "busted." Sines (such as wireless telegraphy and tele- Auseinander nehmen: Take it apart! begins to revolve with a dizzying speed, Ausgebrannt: Burnt -out. phony>, from time to time, promise attractive while blinding blue -white sparks crash all Aber so 'was: Such a thing (of all things). and paying fields to those who wish to along the inside circumference with a noise Verfluchte Amerikaner: Cursed Americans. specialize. The will to do and Special Train- a off all once. Teufelmaschine: piabolic machine. success to you. like hundred cannons set at Zum Kommando, schnell: Quick, to Headquarters! ing will bring The large brewery hall intensifies the ear- Donnerwetter nochmal: By all thunders! The International Correspondence Schoole splitting racket so much that every one is Was ist denn jetzt tos! What's up now? can help you to become an expert in electrical Heiliger Strohsack: Holy hag -of- straw; equivalent compelled to close his ears with his hands. to "Holy Gee." work, no matter what branch you like best. Quickly stepping outside the party arrives Dummkopf: Blockhead. Thousands of young men have already won just in time to see fifteen Boche airplanes Die Funkenstation: The Radio Station. success through I. C. S help. You can do volplaning down and disappearing behind Gott sei Lob: God he thanked. try, Everything is Aber Herr Leutnant: But, Lieutenant! as well as anybody, ifyou the German lines. A French aerial officer Maul halten: Shut up. made so clear that you can learn in your who had observed the German aeroplanes, Löschfunkenstrecke: Quenched Spark Gap. spare time, regardless of where you live or Nordlicht, nicht wahr!: Northern lights, is it drops his glass, steps over to the President, not? what your work No books to buy. salutes smartly and says impressively: Dummes Rindsvieh: Stupid piece of cattle. There's big money in Electricity. Get "Le `cirque' du Baron d'Unterrichter! Grosses Kommando: General Headquarters. after it by marking and mailing the Coupon Its sont hors de combat!" today. Finding out von: you nothing. FRENCH Hors de combat is correct. Von Unter- TRAM OUT NCNB e.-, -sew L'éclateur rotatif et les bouteilles de Ro- -- --, richter was not to fly again for many a Leyde: tary spark gap and Leyden jars. INTERNATIONAL CORRESPONDENCE SCHOOLS week. Le President de la République: The President of We look around to tell the glad news to the Republic. BOX 5391, SCRANTON, PA. Monsieur le President! Attention! Allez! Mr. Explain, without obligating me, how I can qualify for the General Pétain, but the latter has disap- President! Ready! Gol position, or In the subject, before which I mark X. peared into a low brick building where he Messieurs, le jour de gloire est arrivé, vive la ELECTRICAL ENGINEER CHEMICAL ENGINEER now sits surrounded by his staff, poring France!: Gentlemen, the day of glory has Electrician SALESMANSHIP arrived, Electric Wiring ADVERTISING MAN over military maps ornamented with many long live France! Electric Lighting Window Trimmer (This is from the second verse of the "Marseil- Electric Car Running Show Card Writer vari- colored pencil marks, as well as little laise") Heavy EiectricTraction Outdoor Sign Painter brightly -colored pin flags. Telephone and Le "cirque" du Baron d'Unterrichterl Ils sont Electrical Draftsman RAILROADER hors de combat!: Baron Eleetrie Rankine heslgeer ILLUSTRATOR telegraph instruments are all about the von Unterrichter's cir- Telegraph Expert DESIGNER cus! They are out of the fighting! Practical Telephony BOOKKEEPER room. Monsieur le Président, toute P armée Allemande MECHANICAL ENGINEER Stenographer and Typist est en retraite: Mr. President, the entire Ger- Mechanical Draftsman Cert. Pub. Accountant Again the President shakes hands with man army is in retreat. Ship Draftsman Traffic Management Monsieur Sparks, congratulating him on Practise Comme rciai Law Gas ngineer GOOD ENGLISH his achievement. Luncheon is then served CIVIL ENGINEER Common Schad Subjects in former Surveying and Mapping CIVIL SERVICE the office of the brewery, gayly MINE PURER'S OR ENO'R Raiiway Mail Clerk bedecked with the Allied flags along the EXPERIMENTAL CHEMISTRY. STATIONARY ENGINEER Textile Orereeer or Sept ARCHITECT AGRICULTURE walls. But even here, far from the titanic (Continued from page 256) Areblteetural Drallmso Navigator Spanish rotary spark gap, its crashing sparks are PLUMBING AND HEATING PoultryRahiug French Metal Worker AntemobUev Italian audible. Looking thru the window we see Thus the most striking examples are cer- Sheet a wonderful sight. Altho it is broad day- tain electro- positive oxides, as Potassium Oxid (1(20) and Calcium Name light, the entire queer telegraph line is en- oxid (CaO). Present tirely enveloped in a huge violet spray of Occupation - K,O -I- Ha0 = 2KOH electric sparks. It is as if "heat- lightning" CaO 11,0 = Ca(OH)a Street were playing continuously about the whole and No line. No one may venture within fifty feet With the oxides of certain electro -nega- City state of the line. It would mean instant death tive it combines energetically to form acids. by this man -made lightning. SO, -- H2O = H,SO, Luncheon is soon over and more speeches PeOe -I- 31-150 = 2H,P0i are made. Suddenly the door flings open and General Pétain steps in. One look these reactions being strongly exothermic. at Under certain conditions the halogens Health -Strength-Beauty his remarkable features, and all talk vigor. stops (Cl, Br, F) will decompose water Yon can have bodily as if by magic. He crosses the room to- with the success - attaining energy - attractive, liberation of oxygen, which in turn acts as healthful beauty) Ail yours at Draetleelly wards the President, salutes and says in a no cost -the greet benefits of the famous an oxidizer, while the hydrogen forms a VIOLET BAY TREATMENTS- heretofore only pro- calm voice, tho his eyes betray his deep curable at big expense from Physicians and Beauty emotion: haloid acid. Specialists. TREAT YOURSELF at home with "Monsieur le Président, toute l'armée 2CI -{- 2H2O = 4HC1 -F O, RENULIFE VIOLET RAY Hi BeFrequency Allemande en 1, -I- H,SO, -i- H,0 = 2HI H5SO. Transforms electricity into the most powerful, effec- est retraite!!" tive. purifying Health and Beauty giving agency And so it known to science, yet gentle. soothing, perfectly Bats was. The greatest and final Natural Waters. These include all such -no shock nor pain. Eradicates disease from blood. retreat of the Kaiser's "invincible" hordes waters as occur naturally upon the surface flesh. bone and nerves; tones and restores. GET FREE BOOK telling the whole marvelous story of was in full swing towards the Rhine. of the earth which are more or less im- the Violet Ray-Its wonderful successes - Its many use,- specified by physicians More congratulations are to be offered to pure from the presence of dissolved gases for rheumatism, neuritis, headache. Sparks. A medal, . and numerous inorganic substances. These catarrh, wrinkles. blemishes. tilling bait Heavens, where is and 100 other bodily ailments and beauty that young man? But Sparks has slipt waters may be clast as rain, spring, mineral defects. chronic and acute. Get this valuable book by return mail. over to his machines and is standing in and sea waters. RENULIFE ELECTRIC CO. front of the noisy is 537 Marquette Bldg., DETROIT "thunder and lightning" Rain water the purest form of natural WANTED! Representatives to demonstrate to physi- wheel eyeing it enthusiastically. water, but it frequently contains such gases \ Mars and individuals. You benefit by mentioning the "Electrical Experimenter" when writing to advertisers. www.americanradiohistory.com 2 74 ELECTRICAL EXPERIMENTER August, 1918

as carbon dioxid, ammonia, sulfurous oxid a short time the water is turned on to an- and nitric acid in the vicinities of cities, other, and the first dries in the sunlight, and also contains small 'quantities of foreign destroying the germs. matter which are present in the atmosphere Even after thus filtering, the water is and which are carried down by the rain hardly pure enough for drinking. It may drops. be treated in one of three ways. (1) Boil- Spring water is usually found to hold ing the water for some time destroys or- salts in solution. The water supply of ganic life, both animal and vegetable, in- cities is usually taken from lakes or rivers cluding microbes, thus rendering it harm- which are supplied from smaller streams less to drink. This removes nothing except

and springs. These waters contain chiefly volatile gases. (2) . It may be filtered by the carbonates and sulfates of calcium and forcing it thru a Pasteur or similar filter magnesium, with smaller amounts of the made of porous clay (see Fig. 126). This alkalies, iron, silica, and organic matter, process does not take out any dissolved which may be either living or dead. salts, but these are comparatively harmless. Hard and Soft waters. For domestic It does remove any suspended matter, in- or manufacturing the chief factor which de- cluding germs, and leaves the water looking termines the value of the water is its hard- pure and colorless. This is the usual pro- Boys! ness. This hardness is due to the presence cess for purifying drinking water. (3) There's No End of Fun of calcium and magnesium salts, which Distilled water is. the purest. Distillation to Be Had With form insoluble precipitates with soap, which leaves behind any dissolved salts, but it results in the lather failing to cleanse until does not remove gases or even liquids whose CHEMCR AFT these salts have been completely precipi- boiling point is as low as that of water THE BOY'S CHEMISTRY OUTFIT tated. When employed for feeding boilers (i. e, 212 F. -100 C.) ; for example, if alco- hard waters form a more or less coherent hol were mixed with water, it would dis- You can work dozens of wonderful experiments in chemistry and Chemical Magic. You can deposit, commonly called boiler scale, which till before the bulk of the water, but would mystify and entertain your friends by the causes clogging and frequent burning out of not be separated, as it boils. 22 degrees hour, and all the time you are gaining a knowl- the tubes. This is chiefly composed of car - lower than water. A Liebig condenser is edge of chemistry that will be of greatest value to you all your life. bonat and sulfate of calcium with some iron usually employed in the laboratory for dis- Just think of being able to make wonderful oxid and silica. tilling water. changes such as you have seen magicians per- Hard water is of two kinds, temporary form -and you can manufacture useful things hardness and permanent llßrdness. Tem- too -inks that you can write with-aoap- CHEMICAL TESTS OF WATER flreworks -and lots of others. porary hardness is caused by the presence of the bicarbonates of calcium and mag- Experiment No. 139. CHEMCRAFT IS MADE IN THREE SIZES nesium, which may be removed by boiling, Free Ammonia. No. I sella for $1.25 West of the Mississippi and Canada, $1.50 whereby the free carbonic acid, which has Nessler's Test. To determine such mi- No. 2 sells for $2.50 held the insoluble carbonates in solution, nute quantities as 0.0025 we make use of West of the Mississippi and Canada. $3.00 passes off and the precipitation ensues. Nessler's Solution, an alkalin solution of No. 3 sells for $5.00 Thus in West of the Mississippi and Canada, $$.00 mercuric iodid, potassium iodid. When Write for further information and name of dealer Ca(HCO,), -F Heat = CaCO, + H10 + CO. a few drops of it are added to a dilute so- who sells Chemcraft. This temporary hardness may also be lution of ammonia or of an ammonium salt, THE PORTER CHEMICAL CO. removed by the addition of alkali carbonates it forms a deep red precipitat, which, even or hydroxides, thus: in very small amounts, imparts a yellow Dept. B, Hagerstown, Md. Ca(HCO3), -- Ca(OH), = 2CaCOa + 2H2O or brownish tinge to water. Thus Ca(HCO,), + Na,CO, = CaCO, + 2NaHCO, 2H5I, -F NHa = NHg1I + 3HI Permanent Hardness. Permanent hard This precipitat, which may be considered waters contain the sulfates or chlorides of as ammonium iodid, with two mercury magnesium and calcium, or both. Thus we atoms in place of four atoms of hydrogen, may account for the more or less hardness is exceedingly heavy, one molecule of it of water after boiling. These may be re- weighing 541, as against 17 for one mole- moved throu the addition of soluble car- cule of ammonia. bonates, as, for instance Sodium Carbon- When using this test for quantitative WIRELESS ate or Ammonium Carbonate, whereby the work the ammonia in a given amount of The Government and Merchant calcium or magnesium precipitat as car- the water, 500 c.c. or so, is concentrated by bonates. The soluble alkali sulfat which distillation with a little alkali. Its quantity Marine need thousands of remains in solution exerts a deleterious ac- is determined by comparing the color that trained operators. Our special tion when the water is used for boilers. a volume of the distillate gives with a CaSO. -F Na,CO, = CaCO5 + Na,SO. little Nessler's solution, with the color pro- SUMMER COURSE Water is said to have one degree of hard- duced by the reagent in the same volume ness when it contains one part of of Intensive instruction calcium of a very dilute standard ammonium chlo- Starting carbonat or its equivalent in one hundred rid solution. This test when used carefully, July 1st, prepares men quickly thousand. The degree of hardness is de- will determine accurately the presence of for the Naval Reserve, Avia- termined by agitating the sample of the one part of ammonia in one hundred mil- water with a standard solution of soap until lion parts of water. tion, Signal Corps and Merchant a permanent lather is produced. Marine. Purification of Waters. Water Supply is Experiment No. 140. Day and Evening one of the most difficult questions confront- Nitrites. classes. ing Mankind, especially in large cities. After the nitrogenous matter has been Send for latest Prospectus. Ancient Rome brought her water in great sufficiently decomposed to liberate ammo- aqueducts, some of which still remain, from nia, another series of microbes, the so- The Eastern Radio Institute is en- the Apennine Mountains, forty or fifty miles called nitrifying ferments, begin to oxidize dorsed by the U. S. Government away. Lake Michigan is the source of this ammonia, first into nitrites and finally & Marconi Co. Chicago's supply. Boston has constructed into nitrates. a series of artificial lakes in the center of The test, however, is not as delicate as Eastern Radio Institute Massachusetts. These lakes are fed by Nessler's reaction; and, as the nitrites are 899B Boylston St. Boston, Mass. water from surrounding streams. Waters probably a transition stage in the oxida- from such sources cannot be pure. They tion of nitrogenous matter, it is rather rare contain (1) dissolved salts; (2) suspended to get a good test for them in perfectly matter; (3) Microörganisms which are pure water. For this reason, probably the usually harmless, but which may be and significance of their presence has frequently sometimes are the germs of disease. Epi- been somewhat exaggerated. demics of typhoid and scarlet fevers have The reaction is based upon the formation often resulted from drinking such water. of a scarlet coloring matter, one of the Most large city water supplies are now puri- "Azo" dye stuffs, by the action of nitrous RADIO and MORSE fied of germs by running the water over acid upon two aromatic organic bodies. The thoroughly taught at filter beds made of gravel, laid to the depth test is interesting as between a counterpart of several feet (refer to Fig. 125). After of the well known Ehrlick's reaction and Y. M. C. A. flowing thru the filter beds the germs are where the nitrous and sulfanilic acids are TELEGRAPH SCHOOL found to be mostly removed and the water mixed together and the compound corre- Merry Ave., near Broadway, BROOKLYN is collected in reservoirs, whence it runs sponding to the naphthylamin salt is fur- in pipes to consumers. After using one bed nished by the urine. You benefit by mentioning the "Electrical Experimenter" when writing to advertiser,.

www.americanradiohistory.com August, 1918 ELECTRICAL EXPERIMENTER 275

Fill two large test tubes respectively with Croton and with well water. To each add LEARN TELEGRAPHY QUICKER -EASIER a few drops of the saturated solutions of MORSE OR WIRELESS CODE sulfanilic acid, and of naphthylamin hydro - chlorat. A pink or red coloration appearing DJUSTABLE BUZZER PRACTICE SET. shows the presence of nitrites. NO TOOLS -A TO(/CAI OF YOUR F //YCRP ADJUSTS /T. Notice the Croton water does not turn 9 WCKLY GIVES YOU SPEED pink until it has stood for some time, and learn has absorbed some nitrites from the air. This practice set with its adjustable BUZZER enables you to AS SHOWN telegraphy, Morse or Wireless Code, in shorter time than ever before WITHOUT thought possible. A touch of your finger to a thumb screw gives any Experiment No. 141. BATTERY pitch desired to the BUZZER. Especially designed to give very clear Nitrates sound of exceptionally high pitch even on ONE DRY CELL. ,129° The adjustment of the Buzzer to any pitch is made without We can test for these substances in two r--, the aid of any tools -simply by the thumb screw. The great- by reducing ammonia est improvement In practice sets ever made-superior to any ways, either them to base. and using Nessler's solution, or else by di- on the market. Beautifully made ; mounted on substantial rectly producing a colored compound. PRICE $3.50 WITH BATTERY and WIRE Complete Ready for Use (a) Reduction Method. The best reduc- IMMEDIATE DELIVERY Send for Illustrated Folder ing agent is nascent hydrogen, which can be evolved in the water to be tested, by THE TEWNO CO., 41 Park Row, New York City dissolving aluminum in an alkali (as So- dium or Potassium hydroxid). Ale + 2KOH + 211e0 = K,A1s0. + 3Ha or else by the action of the water upon two different metals, such as zinc and copper. High Frequency Bargains When these two, in close contact, are immersed in water, a true galvanic couple is In taking our inventory we found over 200 Violet-Ray machines formed, and the positive zinc is oxidized, of all makes. We selected 100 of the best machines, which we thor- and hydrogen is set free from the negative oughly overhauled in our factory making them better than new. Many copper. This hydrogen slowly converts the nitrates first into nitrites and finally of these machines cost over $40.00. into ammonia, according to the following We have placed all these instruments in two groups and are dis- equations: posing of them for the ridiculously low price of $9.75 and $12.50. NaNO8 + He - NaNO, + ILO NaNO. +3Ha = NHe + NaOH + H2O How to secure one of these This ammonia can be accurately determined by Nessler's Test, and the quantity of machines nitrates calculated accordingly. Send only 50 cents to pay express charges (b) Phenol -Sulfonic Acid Test. We can and we shall send you one of these instruments estimate the quantity of nitrates directly by by express for your examination. This amount noticing the depth of color which they pro- will be deducted from total cost of machine. duce in a solution of phenol in strong sul- You need not accept if not satisfactory. furic acid. The reactions being: Send et once for we shall send the best ma- CoHeOH + HeSO. = C.H2OH.SO,H + HSO chines out first and the quicker you send in and then in the presence of traces of nitric your order, the better machine you will get. acid or nitrates We shall also send our beautiful booklet C.H,.OH. SOaH NO,= C,H,.OH. NOe "Violetta" describing the many uses for the +H +HeSO. high- frequency current. Write us before pur- The color is intensified by the addition of -Ray Machine. an excess of alkali. chasing any kind of Violet (a) Reduction Method Experiments. 11-17 2ADESPLAIN Clean the zinc in a wide -mouth bottle by BLEADON - DUN CO , Dept SS T. adding some water and a little dilute hydrochloric acid, permitting it to effervesce for a minute or two, and then rinse out thoroly. After this, cover with water, add three or four drops of copper sulfate, and let stand for a few minutes until the zinc is fairly RADIUM and covered with a black deposit of metallic RADIUM CARNOTITÉ copper. Then rinse it out well, and fill the Radioactive Salts. containing one micro- Radioactive (Radium Mineral.) The American gram pure Radium. Very powerfull Bril- Pitchblende found in Colorado. from which bottle with Croton water. liant white luminescence in the dark) Substances Radium Is extracted. 10 Milligram of this most carefully pre- Test the reducing action of this "zinc - pared Radioactive Salts. sealed in glase for A generous piece, enough to conduct copper couple" on nitrates by adding two tube (protected by a metal container), experiments. such lie affecting photo - with which every Radium experiment can Experimenters graphic plates thru opaeue material (sim- or three crystals of sodium nitrat to the be conducted. are furnished. ilar to x -Ray pictures). drat made by water in the bottle, shaking it till they dis- Price of one tube of Radium Salts as Sir W. Crookes and Mme. Curie. ie fur- described, sent prepaid $1.00. nished in neat, wooden box. solve, and then letting it stand quietly until The contenta of this tube can be mixed Price of one specimen of Carnotite as with special sulphides to form real Radium the end of the hour. Notice the slow but point. described above. sent prepaid $0.25. continuous evolution of hydrogen, and be- Small bottle of Special Sulphide with Sensitive, prepared Photographic film liquid adhesive, prepaid $0.50. (X-Ray work Rho) to be used for above fore leaving, test the solution- for nitrites Send for one of these preparador,. to- experiments furnished for $0.10 each and for free ammonia, as previously de- day. extra. scribed. CARNOTITE (b) Phenol -Sulfonic Acid Test Experi- SIDNEY SPECIALTY CO., 233 Fulton St., New York City ment. Add one or two drops of sodium carbonat to 50 cc. of the well -water, and evaporate the mixture to dryness in an evaporating dish. This can be done at first TYPEWRITER SENSATION over the flame, but must be finished over the 00 A Month Buys water -bath. Cover the residue with a solution of phenol -sulfonic acid, made by dis- 1e4s1$3 a Visible Writing L. C. Smith Me. Perfect machines only of standard sis. with keyboard of efandard universal arrangement- solving, carefully, in a test tube, a few drops ` has Backspacer -Tabulator -two color ribbon -Ball Bearing oonetruotion -every operating of phenol with twenty times its bulk of convenience. Five Days' Free Trial. Fully guaranteed. Catalog and special price It free. common sulfuric acid. Then add about 10 H. A. SMITH, 738 -231 North Wells Street, CHICAGO. ILLINOIS cc. of Croton water and an excess of potas- For Vol. 1, 2, 3, 4, 5 sium hydroxid. If nitrates are present in the well -water, the mixture will have a INDEX ELECTRICAL EXPERIMENTER 15c yellow or even an orange Color. SCIENCE & INVENTION EXPERIMENTER PUBL. CO. (To be continued.) to Book Dept. 231 Fulton St.. N. Y. You benefit by mentioning the "Electrical Experimenter" when writing to advertisers.

www.americanradiohistory.com 276 ELECTRICAL EXPERIMENTER August, 1918

Submarines, torpedoes, flying machines, machine guns, immense howitzers, the British "tanks,' and an untold number of other products of American brains, are dominant factors in the Great War. We are just starting, our -YOUR-ingenuity must lead to Victory. Uncle Sam -the whole civilized World -is seeking ideas that will aid in the fight. Can't you help with even ONE of thousands of simple things that will win recognition -perhaps fortune for you? The need is for inventions of peace, too. Never before was there such a demand for new ideas of all kinds -never before have so many manufacturers, and other patent buyers, written me for good things protected by OWEN PATENTS. There is, to -day, a market for thousands of ideas including YOURS. Write for my free booklet and see -read for yourself- the hundreds of requests recently received. You incur no obligation by writing me. My advice costs nothing and I make no charge for an opinion as to patentability of your idea. If my opinion is favorable I will back it up by a Guarantee Contract which protects you fully. If you want to sell your invention, I will help you, and will advertise it, free of charge, in "INVENTION AND MANUFACTURING." // A simple request will bring to you at once, my four free books:-"SUC- Edited by CESSFUL PATENTS" a 72 page guide telling how to proceed, gives references, etc.; "STEPPING STONES" tells the truth about prizes for In this Department inventions, gives hundreds of hints of inventions wanted, etc.; PATENT we publish such matter as BUYERS" publishes over 400 requests of manufacturers and others who is of Interest to inventors and partleularly to want OWEN PATENTS, together with ideas they want; "PATENT PRO. those who are In doubt as to certain Patent MOTION," tells you how to sell, why some inventors fail, discusses the Phases, Regular Inquiries addl./sat to "Patent value of your idea, etc. Advice" cannot be answered by mall free of Write for these books to -day. I will send you a signed agreement that charge. Such inquiries are publlsht here for the will protect you before you disclose your invention. benefit of all readers. If the idea is thought to be of importance, we make It a rule not to divulge details, in order to protect the inventor as far it is to do so. RICHARD B - OWL1NPaLeni Lamber s possible Should advice be desired by mall a nominal 164 Omen$po-WashinOton-DC 2276$ Woolmorth B1dQNenL York charge of $1.00 is made for each question. Sketches and descriptions must be clear and apllelt Only one side of sheet should be written en. Invent Something Idea on a Pipe. (244) William E. YOUR IDEAS MAY BRING WEALTH IF PATENTED King Monessen, Pa., Now is the time to patent a meritorious invention. We are con- has hit upon an idea to receiving manufacturers investors make a smoking pipe stantly letters from and in- from a single piece of terested in new inventions protected by patents secured through. BB wood by splitting the en- E. M. TALBERT and which can be turned into money through proper handling. tire pipe longitudinally. Labor shortage has increased the demand for inventions In all lines. It would be held to- New Inventions Help Win the War. gether while smoking by Uncle Sam Wants to means of a metal cap. Write lie today for free and our Evidence of ConCon- - Our advice is asked on this idea. copy of our 104 page ceptlon a n d Disclosure A. A clever idea, but 't has no advantages what- book, 'Bow to Obtain PATENTS Certificate which may soever. As a matter of fact, it is not ractical Patent and What to Invent." At the prove of value and assistance to you. to our mind. By splitting a pipe, particularly the same time send us a sketch, model or Our Credit System will enable you to stem, it would certainly leak and would also photograph with written description file your application and proceed create a false draft. While desirable from a of your invention for our Free Opin- without delay. Patents secured by us hygienic standpoint, it certainly would not work ion and Evidence of Conception Cer- are advertised at our expense to Popu- out in practise. tificate- If your invention 1s proper lar Mechanics Magazine. To protect Our correspondent furthermore submits a sam- subject matter for a patent we will yourself write for our free book and pie made of one piece of tin for tying packages. send you our Certificate to that effect submit your invention to us today. He wishes to krtaw if this device is new and if a patent could be bad on same. TALBERT & TALBERT, 4287 Talbert Building, Wash., D. C. A. This idea strikes us as quite feasible, being Patent Lawyers- Successors to Talbert & Parker that it can be turned out at a few dollars per thousand, which is the all important necessity of such package tying devices. The United States Post Office as well as large mercantile houses require cheap devices of this kind continuously, and I[' PATENTSTS it seems to us that device shown by 16' COPYRIGHTS }f the our cor- HANDY BINDER respondent lends itself readily for such a purpose. for the Electrical Experimenter We think a can be readily obtained. U. S:PATENTS patent

h i,rPl l!1iu°;1li!'{i!i PAY Electrically Operated Shell, MAKE IDEAS 245) Elbert B. White, New London, Ohio, sub. Hundreds of inventions are sold mite an idea to us of an electrically operated shell, help you sell yours the illustration showing the modus operandi. This yearly. We will is a shell supposed to be shot off by an ordinary without cost. gun, it will not explode until it actually strikes inventions to the salt water, which being conductive completes Before sending your the circuit between the outside of the shell and anyone send for our "Blank Form the insulated portion shown at E. A is the wind. of Disclosure" that will Protect ing of a magnet wire to induce a small spark. application is filed B is a rubber tube or other non -conductor to insu- you until your late it in one place from the shell. C is a small in the Patent Office. battery. D is a wire from the small induction Our book "Making Ideas Pay" gives full coil grounded with the shell. E is a wire from information relative to securing Patent Pro- the battery thru a tube so as to go thru the shell tection. Manufacturers are writing us con- and stick out of the latter a short way but does tinuously for new inventions. not touch the shell as otherwise it would short the Blank Form of Disclos- circuit. F is a contacting arrangement to set Send for Book and off the explosive charge. From this it will be ure today. Prompt service. Best results. seen that nothing occurs until the shell actually A. M. BUCK & CO. Patent Attorneys 205 Second National Bank Bldg Washington, D.C. Holds and preserves is issues, each of which L can be inserted or removed at will, without tools. Will keep your magazines perfectly for all time or just preserve them like new till you bind them "EXPERIMENTS" $1.56 permanently. Made of heavy material, By P. Edelman extra strongly reinforced at the back Stands out amongst books Ilke this mag- { O azine does m the periodicals. The one strikes he salt water, which being conductive and covered with handsome green clot suitably lettered in gold C book you want on Science Wonders-Elec- closes a circuit, thus exploding the shell. tricity, Wirers. Chemistry, Mechanics, A. This is a clever idea, and we have never Add Postage for 21b,. Laboratory Stunts. 256 pp. Illustrated. Gold stamped cloth. Guaranteed. $1.50, seen anything quite like it, but we think there is Experimenter Pub. fo., Inc. 233 Fulton St, N. Y. P. EDELMAN, Pub. just one thing wrong with it, and that is that it 1802 Hague Ave., St. Paul, al Inn. will explode too quickly. There should be some You benefit by mentioning the "Electrical Experimenter" when uniting to advertisers. www.americanradiohistory.com August, 1918 ELECTRICAL EXPERIMENTER 277 BUZZER OPERATION TAUGHT IN 600 SCHOOLS. The demand for specialists in the Army is increasing daily. Mechanics and tech- nicians of all kinds, including radio and buzzer operators, are needed by the Signal Corps. In nearly every large city the Federal Board of Vocational Training, thru local school authorities, has establisht schools of Radio-communication where men of draft i "FREE .D1 Ji'.' age who have not been called may receive -\ BOOK - BULLETINS & ADVICE a preliminary course in the operation of radio and buzzer instruments. There are about 600 of these schools where instruction is given, usually in the afternoons and evenings. It takes about 200 hours for a student of average ability to obtain a speed 255 OURAY BLD'G, WASHINGTON, D. C. of 20 words a minute, sending and receiving. Further information regarding schools Don't Lose Your Rights may be secured from local school authori- We publish forms called "Evidence of Con- ties. Electrical engineers and men with ception" by which you can establish your rights before sending the invention to anyone. It is your H. GERNSBACK good fundamental training in engineering best protection. We issue up- to-date bulletins of or physics are particularly in demand for improvements wanted: aid inventors to promote their rights; render reliable opinions free of charge sort of retarding arrangement contained within Signal Corps work. Men of satisfactory and the shell so that the explosion can be timed after qualifications are given three months' secure valuable patents and trade -marks on the shell has sunk a certain predetermined train- reasonable terms. Personal service assured by our to ing in special schools, and have every op- Service Guarantee Contract. References: depth. We believe in this form the shell will 2nd National Bank, Washington, prove practical, and we think a patent could be portunity to take examinations leading to The John P obtained. promotion. Roth Packing Co., Cincinnati. SIMPLY MAIL COUPON LANCASTER a £LLw'1NE, 255 Ouray Bldg., wublegtoe, D.C. Letter Opener. DE FOREST WIRELESS Send me free book "Inventions- Patenting and (246) Henry Gruen, New York City, states: SUIT. Promoting," Bulletins of Improvements Wanted "Altho there are quite a number of letter open- The trial of the patent infringement suit and blank form "Evidence of Conception." ing devices, most of which are operated by elec. brought by the Marconi Wireless Tele- graph Company against the DeForest Radio Name Telephone and Telegraph Company, which Address .. was to have commenced on June 12th in the New York Federal District Court, was, at the request of the Navy Department, sus- for Auto Tires, Doubla ileave, prevent blow - M] to end puncture,. Easiyl applied to any tire. pended by Judge Mayer for the duration .JThoueande sold. Detail, free. Agent, wantad. of the war. Amer.Accessorles Co.,Dept.a3Aincinnatl

tricity or by hand I have invented a letter opener for office and pocket use which works on the principle of the finger nail nipper, having, instead of a blade, a small circular disc cutter, which cuts away a fine shred of paper, while the device is " l a LADE-14ARKSand COPYRIGHTR IGHT being past along the edge of an envelop. The illustration shows the device clearly. This device is not confined to envelops only, but may be Largest Patent Firm used for straightening out sharp edges of sheets t- of paper having a torn edge. Please advise if in the World this device is of any value, if a and patent can Before sending your invention to any attorney or be obtained." manufacturer or disclosing your invention. write A. A very good idea, and we believe it can be for our free blank form I'ROOF OF CONCEPTION readily patented. Firms opening many letters, or in order to protect your invention and secure your even small quantities, would, we believe, welcome rights. This should be signed and witnessed and returned to us. together with a model or sketch and de- a device of this kind. scription of your invention, and we will give a FREE OPINION as to the patentability of the invention. If we report the Invention patentable we will furnish a Certificate Sound Amplifier. Of Patentability. SPECIAL This Certificate of Patentability. together with our blank form (247) Albert DeWolf, Chicago, Ill., has sub- Proof of Conception will protect the inventor and serve as proof mitted an idea of what he calls sound amplifier. OFFER of the Invention until the case can be Bled In the U. S. Patent Victor J. Evans. He makes use of certain acoustic lens to magnify ¡pee. the sound and to concentrate it upon a micro- INVENTORS is as- phone in a certain manner. OBTAINING ASSISTANCE'FOR -Our certificate of great A. This is a very good idea, and we have never sistance to inventors who require financial aid to obtain patents seen it in use. Of course, acoustic lenses are not new, but in connection with a hyper -sensitive OUR FIVE BOOKS MAILED FREE microphone it should prove of great value. We (See Coupon Below) think this device can be patented. to any address. Send for these books-the finest publications ever issued for free distribution. HOW TO OBTAIN A PATENT WHAT TO INVENT Wind Power. Our illustrated eighty -page Guide Book is a Book , Contains a valuable list of Inventions wanted and of reference for inventors and contains 100 mechan- suggestions concerning profitable fields of inventions: (248) Geo. Sparkman, Detroit, Mich., writes as leal movements. illustrated and described. Tells how also inl rrnation regarding prizes offered for Wren- follows: "I was very much interested in the arti. to invent for profit. thins amounting to ONE MILLION DOLLARS. cle 'Electrical Power From Wind' in your March LIST OF PATENT BUYERS number, I have seen the plans of various devices, Contains requests from manufacturers. mail order houses and promoters for patents secured by us and suggestions as to New Ideas they wish to purchase. We place our clients In touch with capital free of ,barge. Wo have recently received over 300 requests from manufacturers. MILLIONS IN TRADE -MARKS Shows the value of Trade -Marks and information regarding unfair competition We advertise Our Clients' Inventions Free in a list of Sunday news - napers. in manufacturers' journals and in World's Progress. Sample Copy Free. We save you time and money in securing patenta Alter the Datent is granted we assist you to sell your patent. WANTED NEW IDEAS n ose a ase a -a ea \ é FREE COUPON!e-a...... VICTOR J. EVANS & CO, PATENT ATTORNEYS but they all appear weak in one point. When the New York Offices: Pittsburg OTCes: Philadelphia Ofllews energy supplied by the wind is too great, there is 1001 to 1007 Woolworth Bldg. 514 Empire Bldg. 1429 Chestnut St. some arrangement by which this excess enc:gy is Main Offices: 779 Ninth Street, N.W., Washington, D. C. allowed to slide by. It is not used, but is a total loss. I am enclosing a sketch of mine which Name Address You benefit by mentioning the "Electrical Experimenter" when writing to advertisers.

www.americanradiohistory.com 2 78 ELECTRICAL EXPERIMENTER August, 1918

remedies this fault. From this it will be seen ing one or more superficial electrons, the that the main driven shaft is connected to a dif- ferential and the energy is transmitted thru a atoms become charged and attract one an- regulator to the motor. When the energy devel- other to form molecules. At close quar- oped by the mill is greater than needed, the ex- ters there is a stray field which draws the Can You cess energy is used to wind up a weight. The molecules together and at remoter distances think of a simple, wind is not a constant source of energy, and even practical when there is a moderately stiff breeze I have the excess of. attraction between dissimilar idea that will fill one of the many often noticed the wheel will stop for a few charges over the repulsion between similar requests we have on file for new seconds. When this occurs, the weight descends (Sutherland's inventions? and a ratchet prevents the shaft reversing the charges causes gravitation It may mean a fortune energy from passing thru the differ- hypothesis). for you. the weight Thousands of things are need- ential and keeps the generator up to normal speed." It is conceivable that this hypothesis, if ed right now. Your brains can help. A. The illustration shows this invention and true, may indicate new electrical methods of Send today for our great new we think it is a very clever idea, altho we do not book- have any means to tell how it will work out in treating materials so as to greatly enhance "Inventions and Trade -Marks actual practice. We believe that a patent can or reduce their strength. he obtained on this device; as far as is known to Their Protection and Exploitation' us, nothing like this exists. and learn more about mak- ELECTRICITY AND THE RANGE ing money from Umbrella. FINDER IN WAR. ideas than (249) A. G. Atchison, Santa Barbara, Cal.,Cal. en- (Continued from page 234) closes sketch of an umbrella with a small you ever window which our correspondent claims is very range -finder no matter what type, operates knew before. It tells desirable when walking against a strong wind. on the principle that a fixed or known base many things that are Read A small window which could be made of celluloid line of a triangle must be utilized. So we Invention and or isinglass is so placed on the lower side of the find that with the "two -man" range -finder, wanted, too. Manufacturing umbrella thru which the pedestrian is able to see A postal will do- The beet thing the approaching person. Our advice is asked, if used for a considerable number of years, lt is free printed for the man this idea is patentable. that the procedure was as follows: The who likes to "dab- A. This is not a new idea, a patent of this fixt known base line was formed of We Help ble" with mechan- kind having been issued years ago, and similar and Our ics. electricity, an imaginary cord stretched between the chemistry, aero- umbrellas are actually being manufactured and Clients nautics. 10c a ooDY sold. two range observers "A" and "B." Suppose from your news that observer "A" equipt with an angle - without charge to dealer. Bend ue 25o Lamp. dollars out for 3 numbers. measuring instrument sights a certain ob- get the Better still, a Si (250) Harris Neil, Laurium, Mich., has thought ject, let us say a factory, of which the range of their ideas bill for years out a containing two filaments, one for -hay- erlptlm 12 bulb "B," now ing facilities none - bright light, the other for dim light, having the is desired. The second observer, possess. Advice free. Don't delay screw section extended to permit a switch to he advances to the point where, when sighting others - operated. Our correspondent claims that there thru his right- angling instrument, he sees get the book at once. are several dimming devices on the market, but thinks that they are too expensive, while he be- both the building in question which forms AMERICAN INDUS/RIES. Inc. lieves his device can be manufactured cheaper. the "object," and also the sighting vane 15 Patent Dept., WASHINGTON, D. C. A. In the sketch and illustration submitted to on observer "A's" instrument At this us we fail to see that our correspondent's device would work any heiter than the ones on the moment "B" shouts, "On!" and observer market now. Furthermore, we doubt very much "A" proceeds to adjust his range- finding if it can he manufactured at all due to technical (angle measuring) instrument until he also "The Book difficulties. makes the reflection of "B's" sighting vane coincide with the object seen in the instru- the Inventor NEW RESEARCHES ON THE ment, and the range is then read off the ELECTRIC BASIS OF MATTER. range -finder dial in yards. This arrange- KEEPS" The science of electricity has now ex- ment is a simple one, but is difficult to apply tended its range into almost all other in modern military maneuvers and battle Worth more than branches of knowledge. The largest and all other patent conditions for the reason that a very long perhaps ultimately the most important, is base line of about fifty yards length is re- books combine& that of the strength and elasticity of ma- FREE. quired. As every student of trigonometry terials. According to the researches of and geometry will perceive, the mathematical Write Dr. Herbert Chatley, of London University, solution of the problem is quite simple, for who has contributed a series of papers to it is based upon the elementary law of LACEY & LACEY the Physical Society of London (England), trigonometry that with a right -angle tri- 131 Springer Bldg. the whole basis of molecular force is elec- I angle having a known base, then the alti- Washington. D. C. trical. Established 1869 tude can be determined when the angular It is now fully accepted by physical chem- value of the opposite angle is known. ists that chemical affinity is due to the ele- The same principle holds good for the mentary charges on the atoms. Many "one -man" range -finder shown schematical- believe in Stark's hypothesis that each val- ly at Fig. C. In this case the range -finder ence bond is formed by a free electron so tube is mounted on a tripod of suitable PATENTS QuVer that a multivalent atom is like a multipolar design so it around on magnet. that can be swung New fflciency in patent service! Report on Dr. Chatley has shown that the a vertical axis as required. This instru- your Invention In two days or lesa. No longer molecular force of cohesion between heavy than 10 days to prepare your case for filing. ment is calibrated to solve the same un- molecules is ten - Get the benefit of my sew pereoonl- service to the thirtieth (a million known quantity, viz. ; the range, by plan. Send sketch of model for prompt search and report million- million -million -million) times great- Hy new 90 -page Patent book FREE! It's "different" determining the angle at the lower comer Send a postal today. er than gravitation and about one hundredth George P. Kimmel. 30 -H Oriental Bldg., Washington. D.C. of the right -angle triangle as shown. To the electrostatic force between a positive take the range with this simplified instru- atom and an electron. He considers that ment the operator proceeds to focus the the fields of the atoms and electrons do not right and left hand prism telescopes of the PATENTS lie wholly within those bodies and that instrument on the object; he then rotates THAT PROTECT AND "AY there is a stray field in the adjacent ether the range index which causes the right hand Books and Advice Free which has the effect of making the groups prism telescope to be inclined inward and I} you want to sell your patent. take It out throuUgqh my (molecules) attract each other with forces he carefully adjusts this part of the appar- goes. HIGHEST REFERENCES. BEST RESULTS. of one or more per cent of those of the atus until the two images in the central WATSON E. COLEMAN, Patent Lawyer electrostatic linkage. These fields are not eye -piece accurately coincide, when the 624 F. Street, N. W. Washington, D. C. uniform but are complexly polarized, so range in yards of the building or other EVERY INVENTOR causing crystallization when the molecules object can be read off the calibrated index should have this book. 'PATENTS AND are free to settle in the positions of maxi- drum. PATENT POSSIBILITIES. h Is sneak mum stability. Within about one and one full of ideas and practical advise, telling The photograph herewith showing Amer- whet to Invent and where to nil. Write tenth molecular diameters at ordinary tem- ican Jackies using a large range -finder on for your copy today. IT 19 FREI. peratures, these forces predominate I have requests for patents upon wand over a battle -ship, illustrates one of the more tnven :ica et all ms.um Can you help eus- the repulsion due to the kinetic energy of recent and extremely high -power p lvit demand? range- le prompt end emcieent oscillation of the molecules, but at greater finders for use with long range guns which (14 rears. experience).erperience). gver, le . i expedient m ptored to secure patents at teeet pooa ibis coat. distances they rapidly diminish until at can fire a shell twenty to thirty miles. H.S. HILL.804 Mrlaebleo Blde, Wsshietlse. D.C. about ten molecular diameters the effect is However, some of these "one -man" range- THE MIDGET SLIDE RULE simply that of gravitation. finders such as used in the Army by will add. subtract, multiply. dl- and vide: solve problems Involving even He thus provides a working hypothesis the Marines, measures about one yard in and uneven roots and powers. Also for the basing of the whole of physical length can gives the logarithms of numbers and be readily carried by the and the Sines and Cosines. Tan- science on electrical forces and motion. observer or by his assistant. This small gents and Cotangents of all angles. There is first the electron primary Its operation is very simple:Cuiek- or ether portable range -finder weighs but five and mathematical whirl, which constitutes the elementary one -half pounds and the operator equipt Durably md f Adapt- ed for shop and omoe use. Fits negative unit of electricity. Grouped about with this truly remarkable and extremely the diameter. the mysterious positive nucleus the elec- simple instrument is enabled to rapidly and riice witch Instructions 1.00 Your money back If rep ere cot satisfied. trons form stable structures with immense accurately determine the ranges of targets Giese Slide Rule Co.. Niles, Mich. kinetic energy, the atoms. Losing or gain- up to twenty-thousand yards distance. You benefit by mentioning the "Electrical Experimenter" when writhe(' to advertiser,. www.americanradiohistory.com August, 1918 ELECTRICAL EXPERIMENTER 279 EXPERIMENTAL PHYSICS. changed into lead peroxid, thus giving us (Continued from page 243) two plates of different substance (lead and Don't Let Constipation Burn You Up lead peroxid) which will now form a cell No wonder you feel the heat, if you are constipated all In 1826, Simon Ohm, after whom the the Ume. IV. the condition of your body more than and give electricity. As the cell gives cur- the temperature; the feverish results produced by the unit of resistance is named, discovered that rent the lead peroxid plate gradually slow poison that is being instilled Into your system. No the flowing a equals the man or woman can be comfortable or healthy while current thru circuit changes to lead again. Thus, charging a this poison Is getting In its deadly work. It shows to electrical pressure divided by the resistance. your face. That sallow, muddy. storage battery is simply changing one of dirty color is lust Impurities work- This can be stated briefly C = V/R where its plates so as to give us two dissimilar ing out through the akin that should C is the current in amperes, V is the press- bave been eliminated by the bowels. plates; discharging is causing the dissimilar It', In YOU breath. Did you ever ure in volts and R is the resistance in ohms. plates to become similar again. breeath`of lbe lhaabituall asttererfrom EXPERIMENT 84- Resistances are meas- constipation t Awful. Of course you ured by the ammeter -voltmeter method or A word in regard to the connection of are tired all the time. dls y. bead - cells and we will close this lesson. Cells scbes, spots Boat before the eyes. by the Wheatstone bridge. The former backaches. Indigestion. rbeumatlsm, connected as in Fig. 77 (a) are said to be can't eat, can't sleep. feel like a method follows: Connect the unknown re- human wreck. sistance a -b, ammeter A, voltmeter V and connected in series. The current is given by the formula C ne /R. + nrl where n GET RID OF THE CAUSE battery cell as in Fig. 76 (a). (The am- = There are hundreds of nostrums on meter is said to be connected in series or is the number of cells, e is the voltage of the market that give relief, but every each, R. is the resistance of the external one of them make the condition directly in the circuit while the voltmeter is worse and fasten the deadly fangs circuit and r, is the internal resistance of of disease more deeply Into your shunted or placed in parallel with the resist- vitals, All cathartics, pills, teas, ance.) Reading the deflections of the am- each cell. When all the, positive plates are drugs and dope overstimulate. caus- connected together and all the negative to- ing reaction which further weaken meter and voltmeter and substituting in the the muscles of the bowel.. Piles, formula representing Ohm's law C = V/R gether, the cells are said to be in parallel appendicitis and bowel troubles are Fig. in case due to constipation and the dope or R = V /C, we obtain the resistance in (see 77 (b)). The current this taken for Its relief. There is lust ohms of a -b. If we have several resistances rl one way rid On, is given by the formula C e /R. REMOVETHE CconatlM Rs, R,, R, etc., and connect them in series = + - STRONGFORTISM WILL SAVE TOE n (see Fig. 76b) we find the joint resistance Strongfortism Is Nature', way. Na- a -b of Rt, R,, R, to equal R. R. where the symbols have the same meaning ture Is the only Healing Force -F + R; in known. Give Nature a chance. No that is, the resistance of several wires (or as the series formula. When R. is large drugs or dope in Nature nor In the most current is gotten by connecting in Strongfortlem. No rigorous. Iron- other forms of resistance) equals the sum clad, muscle-tieing program of tedi- series ; when R. is small, by connecting in aTRONTha °ha exercises; Just Aature', secrets of the individual resistances. If we meas- Perfect Man as I learned them for myself and ure the joint resistance in parallel (see parallel. have taught them to thousands of despondent sufferers. -F I bave put lie Ore and spirit of youth, the Blew of Fig. 76c) we find that 1 /R2 + 1/122 (To be continued) new horn enthusiasm into the hearts of thousands who 1/R 1/r where r is their total resist- bad well nigh given up hope. I have made them young = In masterful strength. vigorous, vibrant, powerful. ance. YOU MUST READ MY BOOK "Promotion and Conservation of Health. Strength and EXPERIMENT 85 -If the plates of a vol- Mental Ener.Energy."gy Sent FREE for three 2c stamp, to cover cost THE PHENOMENA OF ELEC- of peeking and aillnR it will tell you all about the gulch e, taic cell giving current are watched care- simple Strengfort way to develop the INNER MUSCLES' which control the Lee Farces. Write new -today. it will mark a new fully it will be found that bubbles form on TRICAL CONDUCTION era in your exlstanee. the copper and that the zinc is gradually LIONEL STRONGFORT, Physical and Muth Specialist eaten up. This is always found to be the IN GASES. 604 Park Building, Newark, N. J. case, i.e., one plate is eaten up (called the (Continued from page 240) negative plate) and something is deposited conducting surface, they will be attracted on the other (called the positive plate). in By convention we say that the current to it by induction, and eventually coming flows externally from the uneaten to the contact with it they will give up their eaten plate and hence internally from the charges and disappear as ions or rather become ordinary uncharged particles. This eaten to the uneaten plate. Even when the is noticeable in cell is not zinc disappearance especially giving current (unless pure an is pass- is used) we find bubbles forming on the small vessels or when ionized gas zinc; the cause being that small electrical ing thru small tubes, and is there often circuits are set up between the zinc and the more appreciable than that by recombination. Fig. 3, shows the diffusion of ions to the impurities. This action is called local ac- walls of a containing vessel. An easy HEADACHE tion and is obviously a waste, since the zinc means of determining the rates of diffu- is eaten the cell is not any while giving sion is shown in Fig. 4, and is due to J. S. current. Local action is eliminated by Townsend. The ionized air or gas is drawn TABLETS either using pure zinc or by amalgamation thru the tube in the direction of the arrow 27 Years the Enemy of Pain -coating the impure zinc with mercury at a steady rate and after it has past thru )vhich dissolves the zinc and keeps back the a tube T of definite length, the number of For headaches, impurities thus presenting to the solution ions or the amount of the charge in the only pure zinc. gas is measured by the electroscope by catch- Neuralgias, EXPERIMENT 86 -Watch the galvano- ing the charge on the electrode E. Next meter thru which current from a simple different length tubes are tried in place of La Grippe Colds voltaic cell is passing. The galvanometer T and the differences in the charges found deflections gradually fall until practically at E is due to different amounts of diffu- Women's fiches ana Ills, no current flows. The copper plate is now sion in the tubes. heavily covered with gas bubbles. Shake Thus it is that our ability to handle elec- Rheumatic..? SciaticPains the copper plate and you will notice that the tricity and make it do the things we want AL fYo ra 'db rgßi,r fvr 1/f Ta 6/eis galvanometer now reads high again. This it to do depends entirelÿ on the sum total weakening of the current of a simple cell' of our knowledge of what it will do and by the formation of deposit on the positive just how it does it. Nearly every modern . plate is known as polarization. The cur- scientific discovery is merely the develop- 10 is - 25 rent diminished as the cell polarises be- - ment of a principle whose real meaning and cause the surface of the positive plate is secret power lay hidden until someone put gradually covered, thereby preventing the enough study on the matter to see the prac- SP e No!r o g /r. ( yr solution .rd A Í/re Genuine from acting on it properly. The tical connection. J. J. Thomson has calcu- The Antikamnta Chemical Co ,St. Louis modern commercial cells, such as the dry lated the entire quantity of electricity in cell and the wet cell, etc., have chemicals any ionized gas by simply using two quan added to their make -up which combine with titles, the coefficient of diffusion and the this formation on the positive plate, thus mobility of an ion (to be explained below). WAR CONDITIONS DEMAND neutralizing it and preventing polarization. These measurements have led to others of men with training. When using Having trained over such cells continuously they the charge on each ion, etc., and so it is ELECTRICAL 2000 young men. The polarize because the chemicals not with its well-equipped shops and do get evident how closely these quantities are Silos El.etrIoal School, eondowa.d the chance to act. However on allowing laboratories, is peculiarly qualified to give a tied up with the important facts of elec- _urge In Electrical with them to stay idle they recover as rapidly trical theory. Mathe- as the chemicals get at the formation on All ions may have at least two kinds of ENGINEERING matics, the positive Steam and Gas Engines, Mechanical Draw- plate. The storage cell does motion, the characteristic motion of agita- ing, Shop Work, and Theoretical and Prac- not store up electricity as is commonly tion of the ions, due tictl Electricity. Students construct dyna- to their collision with mos, Install wiring and test electrical ma- supposed. It stores up chemical energy. gas molecules, and a rectilinear motion in diploma. Two plates of the same metal (lead) in the presence of an electric field. The former dilute sulfuric acid solution will not form a is equivalent to the average motion of the INyONwE galvanic For practical young men with limited time. 25th year opens cell, but if we first pass electricity surrounding gas molecules when there is Sept. 25th. Catalogue on request. thru, one lead plate will be chemically no superposed electric or magnetic field, and iso TACOMA AVENUE, WASHINGTON, D. O. You benefit by mentioning the "Electrical Experimenter" when writi, g to advertisers.

www.americanradiohistory.com 280 ELECTRICAL EXPERIMENTER August, 1918

when the ions are not close enough together cess of the average velocity of the stars, to mutually influence each other. The dis- a fact very difficult to explain, while the VIORA Y tance then that any ion travels before it hits irregular nebulae appear to be more nearly another particle of the gas is called the at rest than any other class of celestial Portable mean free path. When an ion is acted upon, objects. The planetaries are compara- Therapeutic however, by an electric field the velocity tively few in number. The irregular LAMP with which it is either attracted to or re- nebulae are quite numerous and diversified pelled from an electrode depends directly on in appearance. Tho the origin of the plane- For Home and the strength of the field. In order to com- taries appears to be due to exceptional con- Professional Use pare the velocities of ions we must com- ditions that are out of the ordinary run of Unequalled for the treatment of skin dis- pare them in equal fields so we use the term star life such as possibly chance encounters eases, rheumatic and muscular ailments. mobility. The mobility of an ion is defined of stars with nebulous tracts of matter, hot water bag and gives Takes the place of the as the velocity of that ion in a field of unit the great irregular nebulae appear to be more penetrating and satisfactory results. Highly recommended by the Medical Profes- potential gradient or a field of one volt fall the primordial stuff from which the stars sion. per centimeter. Such a field of unit poten- are fashioned, possibly many at a time from Reflector specially designed to diffuse the tial gradient would exist between two elec= a common nebula in the form of slowly rays thereby covering a large area without a focused heat. trodes charged to 10 volts if they were 10 moving groups possessing the same gen- TWO SIZES centimeters apart. eral drift. As the stars advance in age and in nebulous appendages The determination of the mobilities of gather their 7 inch, $5 inch, $6 under the force of gravitation, they appear -8 ions is only a special case in the determina- For sale at all leading surgical supply stores to quicken their pace but retain their com- tion of velocities discust in a previous paper, and dealers. Be sure to specify the VIORAY. munity of motion. The tendency to move but it gives us a very convenient way of Manufactured by in groups and loose clusters is characteris- comparing ions in different gases and dif- tic of stars well advanced in development ferent kinds of ions to see how they behave VIORAY MFG. CO. as well as new stars and may possibly be 915 Whitlock Ave. Bronx, N. Y. in motion. due to a common origin in one vast irregu- Portable High- Frequency and /I-Ray Apparatus. Early experiments showed that generally lar gaseous nebula. negatives travelled faster than positives, i.e., (To be continued) had greater mobility and that both travelled somewhat slower than ordinary molecules, SEND PICTURES so much so in fact that it was thought the RECLAIMING THE U- BOATS' TOLL ions must be larger, heavier bodies than BY NOVEL SALVAGE molecules, consisting perhaps of from 2 to APPARATUS. 20 molecules in a and cluster, that the page 230) erELECTRICITY negatives are always smaller. Afore recent (Continued from work however has shown that in some gases difficult to apply his method of raising a This latest sensation In elec- negatives submerged wreck, trical advancement-marvel of travel slower, while at lower tem- there would undoubtedly today, necessity of tomorrow, peratures neither travel as fast as would be a considerable field of application for this affords wonderful entertain- be expected, hence they may not be clusters method of performing the operation suc- ment. Affords instruction in after all, but the slowness of their motion cessfully. To start with, Mr. Dawson is the coming science. You can send pictures of your friends may be due to some resistance offered to an economist of the first water, as we shall by electricity over telegraph the charge on the ion. This is one of the presently see, for he has had the fore- wires or by wireless. Picture most interesting points in Modern Physics, thought to perceive that not every salvage in this advertsement was sent and received by this system. for it would mean that the weight of an ion company will care to spend a large fortune Electrical experts and scien- depended upon its charge of electricity, and in purchasing the necessary engines and tiste have declared the Leigh - recent discoveries support this view which other powerful hoisting apparatus with man Electrical Picture Trans- mission System is the marvel will be discust in the following paper. which to raise 'the sunken boat; therefore, of the age. See article December issue. However this may be, it is important to he intends making use of the tides, which Write today for descriptive folder note that recombination and diffusion tell as we know exert a tremendous power L. I. IRISHMAN COMPANY Dept.T. Ogden. Utah us what the conductivity of a gas will be. when properly applied. It also gives us an idea of the size and Mr. Dawson's scheme of raising sunken charge of the ion. boats provides primarily for a large wreck- Re RAZOR ILI mikes ing barge as shown in Fig. "C," and this SHAVING A PLEASURE (To be continued.) carries a powerful engine or motor -driven suction pump. When this scheme is used a reasonable distance from shore, all of the POPULAR ASTRONOMY. power required may easily be supplied by (Continued front page 239) electric cables from the shore, the cables points of resemblance and difference of being supported, at regular intervals if The first Electrical Rayon these two groups of gaseous nebulae. necessary, by means of floats or buoys. The They resemble each other in the nature pump on the barge is connected with a WITH this new Electrical Wonder you get the large suction pipe passing downward to pleasant effect of a massage and a shave at of their light which gives the typical bright the the same time. This razor is on the market line spectrum of incandescent gases at low bow of the wreck . Adjacent to the base of and we are shipping all points in the United States temperature and under low pressure. Their the suction pipe there is placed a large ro- and South America. be tary plow or sand churner, which can be This device can be used without electricity like the luminosity may also due partly to re- ordinary safety razors, but it supposed to be used flected light from stars with which they rotated back and forth by means of a steel with alternating current. The blade moves 7zoo times are associated and partly to some form of cable passing around a grooved pulley at- per minute and actually cuts the hair without pulling. tached to it, and cable being attached Price fto.00. electrical excitation as well as to light of this incandescence. elements to two motor -boats on the surface, one of Vibrating The gaseous that Electric Razor Co., Omaha, Neb. enter into the composition of both groups the boats drifting astern, while the other are hydrogen, helium and the unknown gas drives ahead, and vice versa. In this way nebulium already mentioned. These gases the toothed sand plow is rotated back and "Electrical Worker's Friend" are, moreover, present in both types in an forth rapidly, loosening the sand under the extremely rarefied state and the mass and bow of the sunken vessel and allowing the is sand be up the suction pipe. An electrical book of 66 motor drawings with density of all the gaseous nebulae very to drawn complete instructions for rewinding and recon- small in proportion to the great volume of In order to observe the progress of these necting. space they fill tho the irregular nebulae operations the inventor provides a submerg- PRICE, ONLY $3.50 are tremendously more extensive than the ing tank as shown, and in which an inspec- Write for full particulars planetaries. Both types show the presence tor may be stationed. Where the depth is J. SMITH & SON of dark as well as luminous matter and considerable the tank is supplied with the 1845 Ley Street, N. S. Pittsburgh, Pa. both types are associated only with young necessary air apparatus, as well as tele- stars. The two groups are also alike in phone and electric light. Other conven- showing a decided preference for the fun- iences are provided for also. In cold THE damental plane of the sidereal universe and weather or at great depths where severe VAUDEVILLEDVILLt STAGE in occurring most frequently among the dampness and sweating may occur on the I tell you howl Fascinating profession for densest star clouds. steel walls of the tank, electric heaters either sex. Big salaries. Experience unnecessary. Splendid engagements always As to their most marked points of dif- serve to keep the interior dry and corn- waiting. Opportunity for travel. These ference the planetary nebulae possess a fortable. trical agents and authorities endorse my small, rather sharply defined disk -like ap- As the sand is drawn up thru the suction methods. Thirty years' experience as manager and performer. Illustrated pearance with a strong, star -like condensa- pipe by the pump on the barge, it is mixed book "All About Vaudeville" sent FREE, tion at the center. They are also moving with a considerable quantity of water, and Frederic La Delle, Sta. 246Jackson, MA. thru space with a velocity greatly in ex- may be discharged thru a pipe running to You benefit by mentioning the "Electrical Experimenter" when writing to advertisers.

www.americanradiohistory.com August, I 9 I 8 ELECTRICAL EXPERIMENTER 281

shore, or, if this is not feasible, it may be discharged from a pipe of sufficient length WANT A GOV'T JOB? to allow the sand to escape into the water at War thousands vacancies a considerable distance from the scene of causes B OYS ....Railway Mall Clark ....Customs Podtlaee the salvage operations. $1100 to $2000 $800 to $1500 Build -.Patellar..Patelllar Clark ....Panama Canal Clerk and After the sand has been sucked away C Ier Fly 61400 $1200 to $1800 from under the prow of the wreck, a steel ....Pintailla$ er ....Stenographer $1000 to $1400 $1200 to $1600 Your Own cable is worked under the stern of the boat ....Rural Mall Carrier ....Clerk at Washington by the two motor -boats aforementioned, $600 to $1200 51100 to $1500 :TrainingPlane each motor -boat being fastened to one end Name of the cable and a see -saw action being Address Train yourself In Aviation. maintained until the hawser is worked part Sign your name and address and send us Be an Amateur Aviator with an this coupon immediately. We Aeroplane of your own. Learn way under the hull. For the purpose of will imme- how Aeroplanes are built; learn diately send you (1) a full description of the position the Prmdplee of oonetructton, raising the wreck, the inventor provides checked, (2) a list of many U. S. Gov't Jobs now operation and control. With a number of scows or pontoons, arranged open and directions telling how to get free coaching IDEAL Accurate Seale Draw- for Burs and Building and Flying respectively in pairs, each pair being joined the positions checked. Do It today. Instruction, you can build a by a specially designed and powerful girder. Franklin Institute, Dept. S102, Rochester, N. Y. perfect Model Aeroplane, 3 ft. else, that will nee from the These girders are mounted in roller joints ground by 1ta own rower and or bearings on the pontoons so as to make fly like big one. Send now AMERICAN MADE TOYS WANTED for the Plana for the one you each lifting unit flexible and not liable to want to build. Men wanted to make Toy Soldiers, Drawings ,and Instructions for damage by rough water. Powerful winches Army, Navy and other toys. Homework - Curtiss Mita Tractor are supplied on each pontoon for taking up ere on email scale. Manufacturers on Nieuport Monoplane 5 large wale. Greatest chance for Indus- Taube Monoplane C and holding firmly the cable ends as they trious people for Independent business. Curtiss Hydroplane 2 Enormous demand and future in Ameri- Boat are taken in. The steel cables are drawn Wrightttis Biplane Each ($ can Made Toys. War stopped all impor- cllpeoll Racer ler$1.75) under the wreck by successive operations of tation. Another Industry taken from Germans. Export for 1917 about $3.000,- Send for Our Aeroplane Catalog the motor -boats exerting a see -saw action 000. Toy industry growing rapidly. Some on them as they are placed successively un- People started small, own factories now. Tells about Model Aeroplanes, Racing Aeroplanes, We buy these goods till Christman, for three years. paying Flying Toys, and paru and supplies to build them der the hull. axed prices. Experience or tools not necessary. Hundred with. 48 pages. Send 5 cents for it today. and more made complete per hour. Casting form outfit IDEAL AEROPLANE & SUPPLY COMPANY After the ,various cables have been suc- M$2.75 up. Booklet and Information free. TOY SOLDIER 76.82 West Broadway New York city cessfully engaged under the vessel, the ends ANUFACTURING CO., 32 Union Square, New York. of the cables are delivered to the respective pontoons and applied to the various winches, and here the inventor's genius comes LEARN DRAFTSMANSHIP Send for free Test lesion and valuable information a Month in. He makes the tides raise the vessel in on Draftsmanship. Learn how you 250 The master- the following manner: LESSON can master it at home at hiatus time. piece of watch Easy terms. Unusual opportunities manufacture- adjust- As soon as there is a rise and fall of now due to make Draftsmen earn $25 ed to the eecond, positions, tem- water surface due to tides, the pontoon FREE to a week. Write today. perature and inochroeiem, En- Poo cased at factory into your choice cables need only be drawn taut by the CHICAGO TECHNICAL COLLEGE of theexpaisite new watch cases. winches at low tide, so that when the water $45 Chicago 'Tech" Bldg. Chicago rises, the buoyancy of the pontoons alone 21 Jewel will exercise the necessary vessel -lifting force. When the vessel is thus supported eorA by a series of pontoons, then at high tide Aewund aw Burlington TEL TAPS The great Burlington Watch sent on simple request. the vessel and its attached pontoons may Pay at rate of 82.50 a month. You get the watch at be towed by a powerful tug or tugs into for telephone testing and experimentation. the.same price even the wholesale jeweler must pay. Write Today for Free Watch Book shallow water. If the vessel has not been Price $10- Complete, Prepaid See handsome color illustrations of all the newest raised sufficiently so far, then by towing designs in watches that you have to choose from. it into shallow water at low tide and taking ARTURO COMPANY Your name and address on a postcard ie enough. 32 Broadway New York City Get this offer while it lasts. Write today. up the slack of the cables on the pontoon sil'. os be Co. Dept C 744 19th & Marshall Dbd winches, then at high tide the vessel will morn. again be raised, and so on. MECHANICALLY RIGHT-A REAL LATHE OIL SEALING A Regular lathe, not toy PISTON RINGS ANALYSIS OF IRREGULAR WAVE SHAPED ALTERNATING Gives no Other : results CURVES. PI6TONRIN6 ring an. Every eet ens. guaranteed. 7 years' success. Poynter sires 500. If your jobber can't supply you (Continued from page 247) order direct, P. Poet is quick. Write for tree booklet 04. Swing 4 leeches. 11 inches between oau- AUTOMOBILE ACCESSORIES CO., Baltimore. Md. ten. 17 inches total length. Not weight two simple sine waves, shown in light lines, D Ibes. Shipping weight 18 lb. has Runs on Kerosene The bed of this lathe is machined. as indicated. One of the sine curves Alcohol or Gas Anywhere Workmarthip is ant class throughout. the same frequency as the resultant curve, A most remarkable invention. No Lathe coma equipped with wood tarn - electricity, wires or springs. 1918 Im- lea chuck. Lathe oars be fitted with 8 while the other sine curve has three times proved patented inch face plate and drill (hock as special equipment Ord. Models. Runs 8 hours ono this frequency. for a cent on kerosene, Quiet -Con- today. Prloe $4.50 cash with order. venient. Brings genuine comfort and SYPHER MFG. CO., DEPT. C, TOLEDO, OHIO The relative positions of the two com- satisfaction. Ideal for the sick. proved success. 4th season. Increase ponent sine curves should be noted. Positive your efficiency. Every home and office uild and negative lobes always start out from should have one. The Wonder Fan. Your Own PHONOGRAPH Two Models. Three Sizes. It's Easy With Our Hain the zero starting point in the same direc- BE WELL. KEEP COOL few hones dollars work SAVE tion, and always pass the horizontal datum Lake Breeze Maw ,559 W. Monroe SI., Chicago many dollarsa and gives cut a machine exactly oh \ \a OVER line in the same direction. If the negative BIG PROFITS FOR mlt your ideals YOU Lariat, tone arms case oral ': HALF lobe B could be turned about the horizontal IN BATTERY CHARGING Lariat, blue prints any full datum line as an axis until it comes into Owners of BE 500 watt battery charger. a. s any rec. are clearing $40 to $60 a month extra Youc can make fine pro- the same plane with the positive lobe A, as profit fit building phonographs indicated by the dotted lines and designated So can you. $15 Puts Thirhione ur friends. Maker In Your G Balance Write by C, the complete similarity and symmetry in 9 monthly payments of $20 Mantas wonted each. Write for full particulars terser ready bellt Cho...leoes of A and C may be made apparent. re send $15 with this ad for trial order. Under absolute money -back CUORALEON CO. Fig. 4 shows the same two component guarantee, you run no risk. in position, 708 ?longer Bldg., Elided. sine curves, displaced somewhat HOBART BROS. CO, Bon 8 -E Obi. M. horizontally, and added together, and form- Troy, ing a resultant curve having a very dif- CHEMISTS ferent shape from that shown in Fig. 3. Reagent Bottles (O. S.) each S .40 Evaporating Dishes (2 or.) each .26 DUCK'S However, the symmetry of the positive and Florenee Flasks (8 r.) each .36 BIG 300 pp. negative lobes A and C is to be noted. Sates, Professional 10.80 ELECTRICAL If you need apparatus. send stamp at once for list "B." and WIRELESS CATALOG Fig. 5 shows the same two component We eoUclt your PATRONAGE. We have the QUALITY. We guarantee the SERVICE. 1heiY-,7 'i. L'arjt fo. Mailed upon receipt of 8c in stamp sine curves displaced still more in position, EXPERIMENTAL RESEARCH or coin which may be deducted on L A6HEMICRLEAND first dollar purchase. Catalog con- with a still different shaped resultant. S tains 160 pages of wireless is 183 West 10th Street, New Yeti Monts and 140 pages of electrical It evident then that many different supplies. No bigger or better values shaped curves may result from the alge- Leearn Watchwork, Jewefywork are obtainable lsewhere. We have braical addition of only two sine curves, and complete stock of everything listed -A fine trade commanding a good sal - in this catalog. Wireless orders by simply displacing the two sine curves, G avin be ary, and your services I promptly filled. are always In without in any manner changing their demand. Address HOROLOGICAL Department, THE WILLIAM B. OUCK CO. Bradley Institute, Peoria, Ill., for our latest 230.232 Superior St. Toledo, Ohlo maxima values. Many different shapes catalog You beads by wse,etionisp the "Electrical Es'erimewtey" whew writing to odvertirers. www.americanradiohistory.com 282 ELECTRICAL EXPERIMENTER August, 1918

would moreover result if the positions of phase positions be indicated, altho the rela- Rider Agents Wanted the two sine curves were not changed while tive amplitude of vibration of the reeds and exhibit their maxima values were changed. Fig. 6 might in a measure indicate the compara- Eew ry regar' °ride Motorbike "com - pletely equipped with electric light shows the effect of simply changing the tive amplitudes of the indicated harmonics. and horn, carrier, stand, tool tank maximum value of only one of the com- In general the fundamental principles coaster- brake,e° mud guards and anti -skid tires.Cholee of 44 other ponent sine curves. The resultant curve mentioned in the foregoing disçussion apply styles, colors and sizes in the famous "Ranger" line of bicycles. in this case should be compared with Fig. 3. in both music and in wireless transmission. DELIVERED FREE on approval The horizontal displacement of the com- If Figs. 3 and 5 represent two musical and 30 DAYS TRIAL. Send for big tree catalog and particulars of our ponent curves is the same in both these notes, each having the same pitch, that is Faclordiresi -m -Rider marvelous the same wave length or frequency, the offers and terms. figures. Horns, Wheels, Another important feature to be noted two notes will have very different quality. TIRESLaSun ilea, and parts for The note A on a piano may be readily dis- all bicycles -at' half usual prices. in comparing the resultant curves in Figs. SEND NO MONEY hut tell us tinguished from the A of a violin. The exactly what you need. Do not bas until you 3, 4, 5 and 6 is that in passing from O toX get our prices, terms and the big FREE catalog. one would arrive at the crest of the re- two notes may have the same frequency CYCLE or pitch, but are made up of a different CHICAGO sultant curves, before arriving at the lower, MEAD humps. This is perhaps best noted in Figs. arrangement of sine waves. Likewise two wireless stations might send out waves hav- PER HOUR 5 and 6, the feature of similarity or sym- 35 MILES metry may be clearly emphasized by im- ing the same wave length or frequency, yet Built by boy from Junior parts fur - one might readily be distinguished from Is alahed by us. Any boy can build this agining the lobe C slid along the horizontal car. Parts very cheap. Bend 26 datum line OX until its base coincides with the other because of the difference in. Record cents for blue prints and price list quality. Of This of parts showing how to build this the base of lobe A. Both lobes will then speedy little car. coincide in every respect. The component sine curves making up Car resultant alternating or wireless waves are A very different condition is shown in commonly alluded to as harmonics. The - Fig. 7. The resultant curve is here ob- following table shows at a glance the fre- tained by adding two sine curves, one of quencies and the wave lengths of which has two times the frequency of the the indicated. (upper) odd and even harmonics, from 1 STPHER MFG. CO. other, and different amplitude as to 15 inclusive. It may be noted in this figure that if the tTOLEDOáÓÑIÓ f negative B lobe is turned into position C 9 and then slid along until its base coincides R with the base of the A lobe, the two lobes D do not coincide in any respect. The same E is true of the curve in Fig. 8, which shows R the curve resulting from adding together two sine curves, one of which has Cash with order buys this four N times the frequency of the other. 3 BENCH LATHE O awns a in. s In. C. to C. eblppina Wt.la le. Curves resulting from the addition of PMer Austin 910 W. First E E. Muncie Ind. w sine curves whose frequencies are even multiples of the resultant curves are not SMALL ENGINES symmetrical. Perfected Gasoline Maglnes- If then any alternating pressure or cur- %, 1 and 1% h. y. -for raval and Shop use. Price $19.6, rent curve obtained by experiment, is sym- and up. Also WASHING MACHINES metrical as regards its positive and nega- We ship on trial. Send fer tive lobes, it is made up of sine -curve com- Booklet and Special Offer. CO. ponents whose frequencies are odd mul- X09h1 -11t BPSt RcieEan. tiples of the fundamental frequency. STARTER for FORD CARS Nearly all pressure and current waves found in practise, produced by electromagnetic induction, are symmetrical curves, Learn In SHORTHAND Simplified 6 Evenings ,. Learn Easily at Home and the statement is sometimes made that Prdetieel K. I. Shorthand; quickly such curves or waves consist of the funda- learned. You attain speed easily. mental and its harmonics. Great saving in time and expense. odd i)emonstrating the Peculiar Shape of the Guarantee and so days' triai given. One practical method of determining a Resultant" Curve Obtained by Adding To- Home study. Many endorsements. gether Two Sine Curves, One of Which Has Used in Government service, in cor- number of the harmonic curves or com- porations, schools, professional and Four Times the Frequency of the Other. business offices, private ase tc. ponent sine waves composing any given Br hure and specimen lesson FREE. resultant wave or curve, is by use of a ...Talk as fast as you Ilk?: KING INSTITUTE, ED-300. f denotes the frequency of the resultant curve, frequency meter. One form of frequency in cycles per second. E. I. sbrtkaed." Station F, New York, N. Y. meter, the vibrating reed form, is illus- h. denotes the wave length of the resultant curve. trated by Fig. 9. In this instrument a SAVE 25% to 60% UPPER HARMONICS en need number of small elastic or springy metallic GRAFLEX - KODAKS strips or reeds, 1, 2, 3, 4, etc., are carefully Camerae and Leaser et every deecelptioa. Squat to new. Save money. Writs now for calibrated by filing or scraping them and Frequency Wave length Free Bargain Book and Catalog all rigidly fastened to the same metal base, Odd Even of of listing hundreds of money - saving bargain* in Harmonics Harmonics Harmonic Harmonic Nightly used and new camerae end supplies. All B having attached to it an iron tongue T sold bt i fied1Ooke°.Yu take no rchances that extends over the poles of an electro- with us.r th Ms bes 1 Áa1 16W saw. bossIn photogrenbica magnet, M. If an alternating current is al- 2 /2ñ CENTRAL CAMERA CO., Dept. 118, 121 Ss. Wabash Are., CYtap lowed to pass around the electromagnet the 3 =1/31, 4 =1/41, iron tongue and metal base will vibrate with 5 =1 /5x Convert Your Bicycle Into a Motor -Cycle the saine frequency as that of the alter- 6 7 We complete nating current. The articular reed that =i sell you the motor 8 =Sf =1/81, or furnish you with the finished has the saine natural frequency as that of 9 parts from which you can build the alternating current, will vibrate with 10 =1 =1 /10Ìt the motor yourself with few tools. considerable amplitude; thus indicating, if 11 =1 /111, We send you the printed instruc- 12 = 1/121, tions with owe prints of the drawings for 8.25 er the reeds are each marked, the frequency 13 full particulars for 3 -cent stamp. of the alternating current. Reed No. 7 is 14 =14f =1 /14X STEFFEY MFG. CO., 5025 Brown St., Phila., Pa. shown vibrating in the figure. If the fre- 15 =15f = 1/151, $40 quency meter described has a large num- MOTORCYCLES ber of reeds arranged to cover a large The tab e gives the harmonics up to the and BICYCLES at cut prices. Singles and twine $25 to $100. range of vibration frequencies, a reed hav- 15th for higher frequent' components only; New Motorcycle Tires O. ing a Automobile Tires $3. Best natural period of three times the for lower frequency components the stu- $ fundamental will respond if the third har- dent may construct a table himself, similar MotocyclBeels . Ca ur. handBieyclee M. Tandems $15. Ñw Breleet Fae r 1Mew. monic is present in the resultant wave. to that here given, excepting that each suc- Deninger, The Price Cotter. Rochester, New York The fifth, seventh, ninth, etc., harmonics cessive harmonic has a lower frequency, might also be indicated by a properly de- but a higher wave length. Thus the 4th TYPEWRITERS signed frequency meter, provided they lower harmonic has a frequency of %p and ALL MAKES. SAVE $25 TO $50 on rebuilt by the well -Clown "Young Process." were present in the resultant curve. While a wave length of 41t, etc. .Those who are Sold for low cash -installment or rented. a number of the harmonics might be in- interested in this important subject should Rental applies on purchase price. Write for full details and guarantee. Free trial. dicated by the meter, their amplitudes could read the first article, which appeared in the Young Typewriter Co., Dept. 654, Chicago not be measured, nor could their relative May, 1918, issue. You benefit by mentioning the "Electrical Experimenter" when writing to advertisers.

www.americanradiohistory.com August, I 9 I 8 ELECTRICAL EXPERIMENTER 283 How I Improved My Memory In One Evening The Amazing Experience of Victor Jones

"Of course I place you! Mr. Ad- of whom I have met but once, whose names I tell you it is a wonderful thing, after I can call instantly on meeting them." groping around in the dark for so many dison Sims of Seattle. years "That is all right for you, Mr. Roth," to be able to switch the big search- I light on your mind and see instantly "If I remember correctly -and I interrupted, "you have given years to everything you want to remember. do remember correctly-Mr. Bur- it. But how about me ?" This Roth Course will do wonders in roughs, the lumberman, introduced "Mr. Jones," he replied, "I can teach your office. me to you at the luncheon of the you the secret of a good memory in one Seattle Rotary Club three years ago evening. This is not a guess, because I Since we took it up you never hear any- have done it with thousands of pupils. In one in our office say "I guess" or "I in May. This is a pleasure indeed! the first of seven simple lessons which I think it was about so much" or "I forget I haven't laid eyes on you since that have prepared for home study, I show you that right now" or "I can't remember" or day. How is the grain business? the basic principle of my whole system and "I must look up his name." Now they are did work you will find it -not hard work as you right there with the answer -like a shot. And how that amalgamation fear like playing a fasci- out ?" might -but just Have you ever heard of " Multigraph" nating game. I will prove it to you." Smith? Real name H. Q. Smith, Division The assurance of this speaker -in He didn't have to prove it His Course Manager of the Multigraph Sales Company, did: I got it the very next day from his Ltd., in Montreal. Here is just a bit from the crowded corridor of the Hotel a letter of his that I saw last week: McAlpin -compelled me to turn and publishers, the Independent Corporation. When I tackled the first lesson, I sup- "Here is the whole thing in a nutshell: look at him, though I must say it is pose I was the most surprised man in forty - Mr. Roth has a most remarkable Memory not my usual habit to "listen in" eight states to find that I had learned -in Course. It is simple, and easy as falling even in a hotel lobby. about one hour -how to remember a list of oft a log. Yet with one hour a day of prac- one hundred words so that I could call them tice, anyone -I don't care who he is-can off forward and back without. a single mis- improve his Memory 100% in a week and "He is David M. Roth, the most 1,000% in six months?' famous memory expert in the United take. That first lesson stuck. And so did My advice to you is don't wait another States," said my friend Kennedy, an- minute. Send to Independent swering my question before I could the other six. Corporation Read this letter from C. Louis Allen, who for Mr. Roth's amazing course and see what get it out. "He will show you a lot at 32 years is president of a million dollar a wonderful memory you have got. Your more wonderful things than that, corporation, the Pyrene Manufacturing dividends in increased earning power will before the evening is over." Company of New York, makers of the fa- be enormous. mous fire extinguisher: VICTOR JONES And he did. "Now that the Roth Memory Course is finished, I want to tell you how much I Send No Money As we went into the banquet room the have enjoyed the study of this most fas- So confident is the Independent Corpora- toastmaster was introducing a long line of cinating subject. Usually these courses in- I got in Hue tion, the publishers of the Roth Memory the guests to Mr. Roth. and volve a great deal of drudgery, but this has Course, when it camee my turn, Mr. Roth asked, that once you have an opportunity been nothing but pure pleasure all the way to see in your own home how easy it is to "What are your initials, Mr. Jones, and through. I have derived much benefit from double. yes. your business connection and telephone instructions and feel triple your memory power in a taking the course of few short hours, that they are willing to number ?" Why he asked this, I learned that I shall continue to strengthen my mem- send later, when he picked out from the crowd ory. That is the best part of it. I shall the course on free examination. the 60 men he had met two hours before be glad of an opportunity to recommend Don't send any money. Merely mail the and called each by name without a mis- your work to my friends." coupon or write a letter and the complete take. What is more, he named each man's Mr. Allen didn't put it a bit too strong. course will be sent, all charges prepaid, at business and telephone number, for good once. If you are not entirely satisfied send measure. The Roth Course is priceless! I can it back any time within five days after you absolutely count on my memory now. I receive it and you will owe nothing. I won't tell you all the other amazing can call the name of most any man I have things this man did except to tell how met before -and I am getting better all On the other hand, if you are as pleased he called back, without a minute's hesita- the time. I can remember any figures I as are the thousands of other men and tion, long lists of numbers, bank clear- wish to remember. Telephone numbers women who have used the course send only ings, prices, lot numbers, parcel post rates come to mind instantly, once I have filed $5 in full payment. You take no risk and and anything else the guests gave him in them by Mr. Roth's easy method. Street you have everything to gain, so mail the rapid order. addresses are just as easy. coupon now before this remarkable offer is withdrawn. The old fear of forgetting (you know what that is) has vanished. I used to be FREE EXAMINATION COUPON When I met Mr. Roth again -which you "scared stiff" on my feet-because I wasn't may be sure I did the first chance I got- sure. I couldn't remember what I wanted he rather bowled me over by saying, in to say. his quiet, modest way: beienaent lforporntion Now I am sure of myself, and confident. Division Business Education, 119 West 40th St, New York "There is nothing miraculous about my and "easy as an old shoe" when I get ou of remembering anything I want to remem- my feet at the club, or at a banquet. or in Publisher, of The Independent (sad harper', Weeilr) ber, it be names, faces, figures, in social Please send me the Roth Memory Course of whether a business meeting, or any gath- seven lessons. I will either remall the course facts or something I have read in a mag- ering. to within five days after its receipt or send azine. you Perhaps the most enjoyable part of it all you $6. "You can do this just as easily as I do. is that I have become a good conversation- Anyone with an average mind can learn alist -and I used to be as silent as a quickly to do exactly the same things sphinx when I got into a crowd of people Name which seem so miraculous when I do who knew things. them. Now I can call up like a flash of light- Address "My own memory," continued Mr. Roth, ning most any fact I want right at the in- "was originally very faulty. Yes it was - stant I need it most. I used to think a a really poor memory. On meeting a "hair trigger" memory belonged only to the man I would lose his name in thirty sec- prodigy and genius. Now I see that every onds, while now there are probably 10,000 man of us has that kind of a memory if he men and women in the United States, many only knows how to make it work right. E. E. 88'

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www.americanradiohistory.com 284 ELECTRICAL EXPERIMENTER August, 1918

HOW THREE NEW YORK SUB- along 42nd Street between "Times Square" L. = inductance with the two coils aiding WAYS MEET AND PASS and the "Grand Central" terminal, will un- L. = inductance with coils opposing ONE ANOTHER. doubtedly take care of the heavy cross - L, and L. = self inductances of two coils (Continued from page 226) traffic between the two systems. All values in cms. paying a new fare, you could then proceed Reverting once more to the old subway Now measuring the mutual inductance to Long Island City, or to any intermediate system, which extends northward in the for various positions of the coils with stop. As aforementioned, this route extends lower part of Manhattan along 4th Avenue, respect to one another, as for instance, the downtown along Broadway to Brooklyn, this will be operated as previously and will angle of displacement between the two coils via the Battery, and also has a by-pass be extended by the Interboro Rapid Transit of the variometer or the distance one coil route to Brooklyn via Canal Street. There Company so as to proceed from the "Grand is inside another, in the case of the loose are thus three distinct track levels at Central' terminal northward along Lexing- coupler, we can plot a curve of mutual in- "Times Square," if we include the surface ton Avenue, cross under the Harlem River ductance against coil position. it car or trolley system, while three distinct at 120th Street and from this point will VIII. Measurement of the Coefficient of and important arteries of traffic congre- branch out underground along Mott Ave- Coupling gate at this point as becomes evident. nue, via subway to 157th Street, from which The new 7th Avenue subway tracks point it will operate as an elevated line The measurement of coupling is a very which are four in number, two for local along Jerome Avenue to Woodlawn Road. important measurement in Radio Engineer- trains and two for express trains, join the After crossing under the Harlem River, ing, for upon it depends the sharpness of old subway rails near 45th Street. The this subway route will have a second branch syntony of transmitters and receivers. present four-track subway tunnels running extending eastward to 147th Street and Coupling is usually exprest in per cent, all Southern Boulevard and from here it will over 20% being considered tight coupling run via subway along Southern Boulevard and all below 20% being considered loose Automatic Repeating Rifle and eventually change to an elevated line coupling. at Bancroft street. From here it will oper- In order to measure coupling, the follow- z -Fires _-_i- - ate as an "elevated" along Westchester ing procedure is followed: The circuit is 20 Shots in $ - Avenue to the Eastern Boulevard. The connected as in Fig. 8, and the mutual in- o ductance (M) measured. Then the self - One Loading Wiz_ new Interboro subway plans call for the extension of the present "Bronx Park" inductance of the coils is measured as ex- This is a regular size division, via elevated road, northward to plained under III, and from this data the autdmatic revolver. 241st Street. coupling is found by substituting in the Shoots B. B. shots ob- Only formula: tamable anywhere, M same as other rifles and GA THE DESIGN AND USE OF THE K = X 100 guns. Repeats 20 times 2 V V WAVE- METER. one Hand- with loading. posted = NIL. L. somely finished in gun (Continued from page 249) No caps or load necessary. as it works where K = per cent coupling metal. the current thru the buzzer coils, charges up M = mutual inductance in cms. with a spring and shoots with rapidity and ac- the condenser C of the wavemeter, which with 20 B. B. shot, then L. and L. = self- inductance of two curacy. Simply load in turn discharges thru the inductance L, press the trigger. Nothing to explode - abso- coils in cms. lutely harmless and safe. Remember, it is not producing radio frequency oscillations in A curve can be plotted in this case also, a mere toy, but the same size and shape as a the circuit CL. These in turn are broken showing the per cent coupling against the REGULAR AUTOMATIC. Sent complete with a round of up into a group frequency depending on position of the coils. shot for ONLY 250 postpaid. the pitch of the buzzer. Another oscillating JOHNSON SMITH I CO.. Baal NO 54 W. L.t. St.. Clang. circuit brought into inductive relation with IX. Measurement of the Distributed Ca- NEW BOOK ON the wave -meter will pick up energy as ex- pacity and Natural Period of plained in several places thruout this article. Inductance Coils ROPE SPLICING VII. Measurement of Mutual Inductance Any coil has a certain amount of distrib- Useful Knots; Hitches, Splices, etc. uted capacity between turns, and this quan- Now Dllleroni KnotsAre Made and WhatThey Are Used For Figure 8 shows the method used in meas- tity combined with its self-inductance causes INDISPENSABLE -ro, EVERY MECHANIC AND RIGGER uring the mutual inductance between two the coil to respond to some wave -length PRICE A most practical handbook' giv- coils such as the two coils of a variometer which is known as its natural period. A log complete and simple direc- or loose coupler. 20C Ld for making all the most receiving set having a coil therein that has tion A known capacity C, is connected in shunt a natural period within the range of the ' useful knots, hitches, rig- with the two inductances Li and L. which ..-"f L100ging, lustres, etc. Over receiver is very inefficient, because at some , l00 illustrations. All are connected in series with each other. - ' u k` wave-length the coil is going to oscillate at C about were rope A double -pole, double -throw switch is con- ttaehmen its own natural period, and weaken the re- inn, block tackles,tackles. nected in circuit as shown so as to reverse ceived signals considerably by absorbing ,,a etc. 87 Mrealc Knots the current in coil L,. When the switch is Y m illustrated. Of value to energy in order to keep itself in a state of ee Pe. riggers. campers. thrown to the side A, current flows thru oscillation. The same holds true to a lesser boatmen: Pelee 20 .ostpaid. the two inductances in the same direction, JOHNSON SMITH I CO, De*t. 575, SI W. Lea. SI, Cl,.... degree with the transmiting helix, and for thus causing the fluxes to be in the same this reason helices usually have only enough direction or aid. In this position the two "The Baby" Ñ m.narlesan Revolver turns to give the required inductance, while me ond Most DNecar. Weapon. Hlowarew M. 4% coils are said to be aiding. receiver w.... Long. Takeo Popular .22 Calibre Cartridge* $ inductances are split up into sec- When the switch is thrown to side O, tions by means of end -turn switches or rrainy current passes thru the coils in opposite °.tOn,O °ia....0êpiswas "dead -end" breaks. ° 7:. rm+.a.r directions, causing their fluxes to oppose ñ:<'é.'.1,°°'ml..""41:41,,f7 .. \Iii The accompanying figure 9, delineates the Sum°«`:. -i,Do each other. In this position the coils are method of measuring the natural period of said to be opposing. If now a wave -meter .mod n'A n. ed a coil. The wave -meter is excited by a lo melon is brought near to the coils the wave -length I... A greet restore . way buzzer and inductively coupled to the coil of the circuit can be measured in each posi- .e under measurement which has a unilateral ß°ú..d rl.te°r°.: of Ì1 th..l.d.N3r+a IÓro ° di.: -taliT. tion the switch. Then knowing the value orb. e..m v.meeauol.m I1 °.é.mel .7°Lt. u,.1.b:leutr.Rell connection of the telephones and detector. in of the capacity and the wave-length it re- :r r* °ñ°e.t emiei °1.. á é.:é buraiof Cy1Me:. 7.1.17 lt As the condenser of the wave -meter is ml

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seEXPERIMENTERS! Student's Chromic Plunge Battery 999 This to an ideal battery for electrical experimental work where a very powerful current Is not required. This battery will light a 2 volt lamp for several hours on one charge; it will rim a small toy motor surprisingly well: it will do small electroplating work: it is Ideal for testing work; it gives fairly steady current, and as the zinc electrode can be pulled clear of the electrolyte. no materials are used when bat- efi tery stands idle lies[ Amalgam Zinc only is used, as well as a highly porous carbon to ensure a steadier 'current We furnish enough chromic salts for 4 harms. Full directions for operation and care of battery are Included. battery tests 2 volts and 6 amperes when set up fresh. Not over 2 amperes should be drawn from battery continuously. By using six or eight of these batteries, e great many experiments can be performed. No solution can run out of this battery 1f upset by accident. This makes it an Ideal portable battery. Size over all is 5 "x2 ". Shipping Weight 1 lb. No. 999. Student's Chromic IMMEDIATEE SHIPMENTSI 7 The "Electro" Radiotone HIGH FREQUENCY SILENT TEST BUZZER This instrument gives a Wonderful high pitched MUSICAL NOTE 1n the receivers. impossible to obtain with the ordinary test buzzer. The. RADIOTONE 1s built along entirely new lines; It is NOT an ordinary buzzer, reconstructed in some I`r.nn[Faus. , manner. The RADIOTONE has a single line steel reed vibrating at a remarkably high speed, adjusted to its most efficient ul frequency at the factory. Bard silver contacts are used to make the instrument last Practically forever. EI Yes. the RADIOTONH is SILENT. In fact, it Is so silent that you must en ( { 1 iJ II place your on ear top of it to bear its '+íiY JI beautiful musical note. .v You will be astounded at the wonderfully clear. 500 I 11 Atuewn.m. ñme u cycle note. sounding _ _'i iavaaaemr __-. . sharply in your receivers. To learn the codes. there Is absolutely nothing Ilke It. With the radlotone, a key and one dry cell and ANY telephone. a hy line learner's set is had. Two or more such sets in series will afford no end of pleasure for intercommunication work. Shipping Weight I lb... Badlotone as described each J ,{. IMMEDIATE SHIPMENTS mi The "Electro" Telegraph is not s toy. but a practical, honestly built telegraph outfit, which not only sounds but works like the big commercial Instru- ments. By studying the Bode for 30 days you can become a first -class telegraph operator. Such operators are in big demand now. Outfit consists of TWO complete telegraph instruments each measuring 336 x 21/2 x 21/4. All metal parts are highly nickel plated. including key lever. Note bard rubber knob. Telegraph Code Chart. telegraph blanks and connecting wire comes with set but no batteries. Outfit works on 2 dry cells (one cell for each Instrument). The Electro" is the ONLY Outfit that works both ways, each station can call; no awltebes, no extras. Nothing to get out of order. Guaranteed to please you or money back. Price Completo as Illustrated (TWO INSTRUMENTS).. .25 Shipping Weight, 2 ¡be. YY]7's'tds IMMEDIATE SHIPMENTS The "Electro" Codophone (Patents Pending) What this r e m arkabla $1.50 : Instrument Is and does. No. EX2002 The "Elec. BOY'S TOYS" - tro" Cod o- to rHE ELECTRIC contains enough mate phone is rial TO MAKE AND COMPLETE OVER TWENTY - positively the 1 only instru- FIVE DIFFERENT ELECTRICAL APPARATUS with- ment made out any other tools. except a screw -driver furnished with the outfit. The box that will contains the following complete instruments and apparatus which are already Imitate 5500 cycle note assembled: as Student's chromic plunge battery, compass-galvanometer, solenoid. telephone heard tlin ..., 1999 receiver, electric lamp. Enough various parts, wire, etc., are furnished to Wireless re- make the following apparatus: ceiver. The Electromagnet, electric cannon,' magnetic pictures, dancing spiral, electric loud -talking receiver equipped with a born, talks so loud that you can hear hammer, galvanometer, voltmeter, hook for telephone receiver. condenser, the sound all over the room, even if tbere Is a lot of other noise. THAT'S NOT ALL. By lessening or tightening the receiver cap, a tone sensitive microphone, short distance wireless telephone, test storage battery, from the lowest, softest quality, up to the loudest and highest screaming shocking coil, complete telegraph set, electric riveting machine, electric buz- sound can be had In a few seconds. zer, dancing fishes, singing telephone, mysterious dancing man, electric jump- FOR INTERCOMMUNICATION. Using two dry cells for each Instru- ing Jack, magnetic geometric figures, rheostat, erratic pendulum, electric but- ment, two Codophones when connected with one wire and return ground. terfly, thermo electric motor, visual telegraph, etc., etc. can be used for Intercommunication between two houses one -half mile apart. One outfit alone replaces the Old -fashioned learner's telegraph set, con- This does not by any means exhaust the list, but a great many more ap- sisting of key and sounder. paratus can be built actually and effectually. The Electro" Codophone Is a handsome, well made instrument, fool With the instruction book which we furnish, one hundred experiments that proof. and built for hard work. Contacts are of hard silver r/i inch in can be made with this outfit are listed, nearly all of these being illustrated diameter, that will outlast the instrument There s also a neat codo chart and full directions enabling any intern- with superb illustrations. No other materials, goods or supplies are neces- gent young man or girl to learn the codes within 30 days. practising one- nary to perform any of the one hundred experiments or to make any of the half hour a day. 25 apparatus. Everything can be constructed and accomplished by means of Sisca: x 3 x 2%". Shipping weight, 2 lbs. this outfit, two hands, and a screw-driver, The "Electro" Codophone as described, complete $1.50 The outfit contains 114 separate pieces of material and 24 pieces of finished articles ready to use at once. Our big, new electrical cyclopedia . 19 is waiting for you. Positively Among the finished material the following parts are included: Chromic salts the most complete Wireless and electrical catalog In print today. 228 Big for battery, lamp socket, bottle of mercury, core wire (two different lengths), Pages. 600 Illustrations. 500 instruments and apparatus etc. BIgR "Treatise a bottle of Iron filings, three spools of wire, carbons, a quantity of machine on Wireless Telegraphy." 20 PREE coupons for our 1610 -page FREE Wire- less Course in 20 lessons. FREE Cyclopedia No. 10 measures 7x51/2", screws, flexible cord, two wood bases, glass plate, paraffin paper, binding Weight rh posts, screw-driver, etc., etc. The instruction book is so clear that anyone can lb. Beautiful stiff covers. make the apparatus of without trouble, and besides a section the instruction 111 Imoa 11 -(nail imbook is taken up with the fundamentals of electricity to acquaint the layman - - - with all important facts in electricity in a simple manner. ELECTRO IMPORTING COMPANY We guarantee satisfaction. 231 Fulton St, New York CRY The size over all of the outfit Is 14 x 9 x 23g. Shipping weight, 8 lbs. $5.00 herewith cents In for Ne. EX2002 "The Boy's Electric Toys." outfit as described which pleasee t latest Cyclopedia Cats- IMMEDIATE SHIPMENTS log No. 19 as described. 231 Fulton St. NAME ELECTRO IMPORTING CO of NEW YORK ADDRESS

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You benefit by mentioning the "Electrical Experimenter" when writing to advertisers. www.americanradiohistory.com 286 ELECTRICAL EXPERIMENTER August, 1918

r .11 Laboratory Chemistry By Richard B. Moore, Instructor in Chemistry, University of Missouri. Contains 195 pages, innumerable illustrations and experiments. Printed on highly finished book paper. Handsome stiff cloth cover. FREE with a year's subscription. lj .REL Add fnr t lb. Experimental B Electricity Course S. GERDISBAC This masterpiece contains 160 .LESCAIZ pages, 400 illustrations. Size of book 5 "x9 ". Printed on 8í11.W. extra thin paper, so book can be slipped into pocket. Hand- some stiff cloth cover. FREE with a year's subscription. A.td 3c for postage

Wireless Course The most comprehensive Wire less Course ever printed. Contains 160 pages, 350 illustrations. Size of book 61/2"x9". Very fine flexible linen cover. FREE with a year's subscription. Add 5c for postage Read This Remarkable Offer It may be withdrawn at any time, due to the tremendous cost of paper, which IS JUST DOUBLE WHAT IT WAS ONE YEAR .AGO. We only have a limited supply of these fine books on hand; after they are gone we cannot reprint the books until conditions become normal again. THIS MAY BE TWO YEARS OR MORE. Now is your chance. The publishers of this journal have earned an enviable reputation of giving more than 100 cents' worth for each dollar spent with them. Profit by this liberal opportunity NOW; it may never be made again. HERE'S THE OFFER R-l8 Subscribe to the ELECTRICAL EXPERIMENTER for one year, at the Gentlemen: \ regular subscription price of $1.50 per year (Canada, foreign Ind Please enteer. N. Y. C. $2.00) and we will send you FREE any one of the above books. St b n If you subscribe for two years, TWO BOOKS WILL BE GIVEN FREE. too the rt ELEC- All THREE will be sent FREE with a three -year subscription. TRICAL EXPERI- 9íA \ BOOKS MEN E'ER for the If you are a subscriber at present, take advantage of this wonderful term of year Q opportunity anyway. If you do, we will extend your present subscrip- for which I enclose here- tion from its expiration date. with E You will also send me at once This Offer Limited. Act Now. FREE your book 223 EXPERIMENTER PUBLISHING CO.,

Name Address

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www.americanradiohistory.com August, 1918 ELECTRICAL EXPERIMENTER 287

Opportunity Ad -lets will.find many remarkable opportunities and real bargains in these columns. It will pay you to read and investigate the offerings made YOUevery month by reliable firms and dealers all over the country. No matter what you may be seeking, whether supplies, automobile acces- .ories, the opportunity to make money, or anything else, you will find listed here, the hest and most attractive specials of the month. Advertisements in this section six cents a word for each insertion. No advertisement for less than 60e accepted. Name and address must be included at the above rate. Cash should accompany all classified advertisements unless placed by an accredited advertising agency. Ten per cent, discount for 6 issues, 20 per cent discount for 12 issues from above rate. Objectionable or misleading advertisements not accepted. Advertisements for the September issue should reach us not later than July 22. OVER 100,000 CIRCULATION GUARANTEED, A. B. C. AUDIT EXPERIMENTER PUBLISHING CO., INC., 233 Fulton Street, New York, N. Y.

INlIIIIIIIIIIIIIIIE111IIllll lIIIIIIIIIIWIIIliltIIIIMIIm1IIIIIIIlIIl'JI))'hull)IIImumIIIIIIIIIIIOIMa m! IIIIIIIIIIIIIIIIIII IIIIIIIIII IIUWWIIIIIImIIIIIIWIIII II IIWIIIIIIIIIUU Illlllllll IIWIIIIII!III&fIIII11111I11 IIII mllllc mllllllllNlnI1111III1WIIlIIIUMIIII11uI118uWIIIIIIIWIIIlIlumuulWlll IIII WII VIII IIHWIIII IIJI IJIIi mmt Automobile Accessories Business Opportunities Auctions

Fords Can Burn Half Coal Oil, or cheapest Make Die -Castings. Sketch, Sample, Booklet Auctioneers make from $io to $55 a day. Free gasoline, using our 1918 carburetor; 34 miles and Proposition sac. R. Byrd, Box 227, Erie, Pa. catalog. Missouri Auction School, Kansas City. per gallon guaranteed. Easy starting. Great $30 a Week -Easy money home evenings. Free Blluml111811 1161 IImfII111111mllml llll lml! Illmn111111IIWIIIIIIIIIIIIuffiIn;IIIImIte IIIIIIIIIIWmlllanll power increase. Attach it yourself. Big profit booklet explains. Send stamp. Alec Scott, For Advertisers selling for us. Thirty days trial. Money back Cohoes, N. Y. guarantee. Styles to fit any automobile. Air - Free "Quick- Action Advertising-How it is Build- Friction Carburetor Company, xpo Madison How to become a successful inventor. particulars. Engineers, 2548 Armitage, Chicago. ing Business for the Progressive Advertisers of Street, Dayton, Ohio. America"; A little story of RESULTS, told by Special Luminous Paint, 15c; Silver - EmIImIIIIIIIffinuenuffi anlllm immlmmlllllmll 111llmll llllaIlllulmumllmlmmmmni Offer- the advertisers themselves-not the publisher. Plating Powder, i c; Liquid Courtplaster, ssc; You will be interested in reading this little Aeronautics Soap Bubble Liquid, x5c; Straw Hat Bleach, s5c; booklet which Paste, Resilvering we have prepared for prospective Collapsible Tube Tooth Is; advertisers, a copy of which be gladly Aerial Age, America's leading illustrated Mirror Liquid, 15c Polish for Tan Shoes, r c- will weekly, presents the latest developments in Make Oil mailed to you upon request. It tells you how Dressing for Tan Shoes, isc; Paint to to talk business with i,o00,000 intelligent, aeronautics throughout the world. Up to the Cloth, 15c. Full Directions how to make and use. inter- minute technical Information concerning aero- ested and responsive Americans every month Full set of so recipes only soc. Remarkable men - engines, aeroplanes, accessories and patents. Sidney Specialty who know what they want and who have bargain. Stamps accepted. the money to buy it. Write for particulars and Complete model, news and instruction. Trial Co., 233 Fulton Street, New York City. subscription six months, twenty -six issues, one rates -today. Douglas Wakefield Coutlee, 225 28o Madi- "Quick -Action Advertising -How it is Build- West 3011 St., New York. dollar. Sample copy toc. Aerial Age, ing Business for Advertisers of son Ave., New York City, N. Y. the Progressive RIm!mlllmmlmntllnnuminlllmulminmmuumnlnlmnllInintionuuimmiunni mnlIlmnnu America: A little story of RESULTS, told by MEN -Learn Aviation Mechanics & Aeroplane the advertisers themselves -not the publisher. Cameras Construction. Shop and Field experience. Gov- You will be interested in reading this little Sale- Cameras. makes, ernment needs you. Write today. Moler Aviation booklet which we have prepared for prospective All all sizes; new and School, ioy S. Wells Street, Chicago, Ill. second hand. Jacob Feigenbaum, io5 St., advertisers, a copy of which will be gladly New York City. i® IIIIWW8111111WIImnmlmm l®mlmllWmml158111 nml ffirs nllmmlmnmmmlmul0 mailed to you upon request. It tells you how Agents Wonted to talk business with I,oco,000 intelligent, inter- mail IIINIIIIImII llllll®WIWWIIumminrumplum ituunmoo mmnnmunllnmlun®mut ested and responsive Americans every month - Chemicals men who know what they want and who have Insyde Tyres, inner armor for automobile tires, Perform all the Chemical Experiments this double mileage and prevent punctures and blow- the money to buy it. Write for particulars and in rates today. Douglas Wakefield Coutlee, 225 magazine with our wonderful chemical outfits. outs. Quickly applied. Cost little. Demand We handle complete tremendous. Profits unlimited. Details free. West 3oth Street, New York. lines of apparatus, chemi- advertisement here cals, and minerals. All sizes and prices. Par- American Automobile Accessories Co., Dept. 54, Mr. Business -Man -Your ticulars free. Liscien Institute Cincinnati, O. will be read by over too,000 live prospects. The Mathews Ave., Ad- lets" of the Electrical Ex Knoxville, Pittsburgh, Pa. Profit of $27.50 can be made on our $2.5o Pre- Opportunity perimenter bring quick and positive results. Prepaid 80 Different Chemicals $4- Mercury, mier Transfer Outfit' applying letters and flag Sodium, Iodide, Magnesium, emblems to automobiles, windows, trunks, bags, For proof of what they have done for others ad- Aluminum, Uranyl- dress Classified Department, 233 Fulton Street, Chloride, Silver Nitrate, Mercuric -Oxide, Zinc etc: Demand unlimited. A positive money New York. Dust, Iodoform, Manganese Dioxide, Calcium maker. Auto Mono ram Supply Co., 83 Niagara Sulphide, Hydrochloric, Oxalic and Acetic Acids, 1 1 nlm8801 Bldg.; N. J. 01 11IINI1WWIIIIII61811hf11 11 6 1111m 101011 ®171111 1786881615M4li Ncwark, together with 65 others. All are contained in Prise Contest- Selling Liscien apparatus, Books glass bottles. Generous quantities of each. We minerals, chemicals, during vacation. Particulars To Get Better Pictures: Read the Amateur do this to advertise the purest chemicals manu- for stamp. Appel, Mathews Ave., Knoxville, Photographer's Weekly; illustrated; weekly factured. Full list sent free upon request. Sent Pittsburgh, Pa. prize competitions; print criticisms; many prepaid to any address in the world, $4 complete. Automobile lettering yields big profits. New unique features; $1.5o per year; three months' C. O. D. terms accepted. The Swimmer Chemical method. Easy, leasant, fascinating spare time trial subscription 25c. Abel Publishing Com- Co., 1849 Park Place, Brooklyn, N. Y. employment. Miller Sales Company, Dept. X, pany, 401 Caxton Bldg., Cleveland, Ohio. EXPERIMENTERS! Send 25c for new list of Lexington, Kentucky. Read "A Man's Secret," 25c. Paul Duff, 413 chemical experiments -BLUEPRINTED -circular Exclusive county rights. Sell Tankii; modern Mozart, Chicago. of other new things in chemistry. Royal Pub- lishing Co., Box 1054, St. N. B., Canada. auto fuel; profitable; guaranteed. Tankii Co., What Every Draughtsman Should Know. Very John, Cleveland, Ohio. useful booklet. Price only ten cents. Wack Experimenters! Mystifying, Instructive! Out- IIMnllunlllnulnnlmllmlmmminu! ImluIIlllmu1111WIIIIIlIII11mrwIIIWIIB :II IIIIIIWIIIIWIIIIII of luJ Booklet Co., 5943 Patten St., Philadelphia, Pa. fit Chemicals for fifteen cents, coin. Car- Electrical Supplies and Appliances roll Whitney. 714 Vinton St., E. Waterloo. Iowa. Learn the scientific way of playing cards. nllllmnnmm tWIIIWIIIIUWIIWM81611611WIIIWIIMIIIDIIIi Write for free pyarticulars. Detroit Book Co.. WIIWII IWIIWWWIIWIIIIIIWII IWi Lamps That Stop Pain Quicker than Narcotics Box 5o, Detroit. Mich. Help iVanted Improve -Heal Ulcers, Circulation. to day The trial offer and free booklet. Dept. 3, Magic Pain A Binder for Electrical Experimenter will Wanted Immediately -U. S. Government wants preserve your copies for time. Price, soc. Relieving Lamp Co., 546 Garfield Ave., Chicago. all thousands, men -women, 18 or over for war Postage on 3 lbs. is extra. Send for one today. Electrical Tattooing Machines $3, $5 and $7.00. positions. Easy clerical work.. $loo month. Experimenter Publishing Co., 233 Fulton Street, List positions open free. Catalogue free. Prof. Jack Temke, 517 Central New York City. Write immediately. Ave., Cincinnati, Ohio. Franklin Institute, Dept. S26, Rochester, N. Y. Fire Sale of Slightly Damaged Books. Due to Men Wanted to make Toy Soldiers and other Vacuum Research is attracting the live ex- fire in our stock rooms, a great many of our perimenter. Tubes, pumps, etc., made to order. Toys. See our advertisement on page 28r. books were water stained, but not otherwise Toy Soldier Mfg. Co.. 32 Union Square, N. Y. Pump in Tune Experimenter $r.5o. E. Kurth, damaged. Rather than dispose of them to deal 16 South West, Princeton, N. J. ers we prefer to give our readers the benefit. 4mlmm llmlllll!IIIIIIWIIrmIm110111 mIWIIlnnnImllmlllllmlllluulWIIWllnmumnlumllnn IsiIshl "Hot -point Domestic Electric Irons $4.50 Pre- Look at this list! Our celebrated Wireless Letter Specialists paid. Dealers price $5 to $5.50. Your last oppor- Course, i6o pages, 40o illustrations; Experimental tunity at $4.5o. Over 3,000,000 in use! With Electricity Course, 16o pages, 35o illustrations; Letten that Land Orders written for $q.00. Cord and Plug, Hot -Point," cool handle, at- How to Make Wireless Sending Instruments. Forceful and convincing literature of every de- tached stand, thumb rest, and hinged cord These three books for $i.00 prepaid. Regular scription at attractive rates. Criterion Service, protector. Absolutely guaranteed. Order now! selling price of these three books is $z$o. We Dept. 12, West New York, New Jersey. Ask for illustrated folder. Baer Electric Com- guarantee you will be satisfied. Experimenter 018mmulIm1ImIWmImummulllm in lmnurimtoImunlingu Bllmmlmllnnmmmlmllnm pany, Van Wert, Ohio. Publishing Co., Inc., 233 Fulton St., New York Models and Model Supplies Batteries and Flashlights-Best made. Copy City. of Morse code and catalog free. Colonial Com- Old E. E. Back Numbers: We have some valu- Producers of Results: Inventions developed pany, Woodhaven, N. Y. able old E. E. back numbers on hand Models, Experimental Work, anything special as follows: in metal to order, novelties, spinning castings A Bargain, ew Robbins & Meyers Motors. 1915 -Jan., March, April, June, July, Aug., Sept., Oct., Nov., Dec., each 35c. 1916 in any material, electrical devices, patterns of One tenth I -l.P., no volts, 8,000 R.P.M. Uni- price -n., Feb.. March, May, June, August, Sept., (Oct., Nov.. all kinds, plating, general manufacturing, de- versal. Not a toy, $goo each. Doubleday - stamp- Hill Dec., price each 3k. 1917 -Jan., Feb., March, signing, special tools, punches and dies. Electric Company, Pittsburgh, Pa. Apr., May, ings. Send drawing or sample. Expert infor- June, July, each 35c; Aug., Sept., Engineering Company, Amateurs, Attention! ! ! Oct., Nov., Dec., each mc. 1918 -Jan., Feb., Mar.. mation free. John's We have on hand a small quantity of slightly Apr., each toe; May, June, each rsc. Dept. E, Cleveland, Ohio. damaged July, We pure Bakelite bases. Bases are new, can fill orders at once upon receipt of your re- ffIIIWIIIWIIIIImumllllum111EI lumlmMU®ullluulumnIIImhutmnti lnnnnmmlllimllunl except slightly imperfect at one side, edgewise. mittance, and if you have not these numbers Motion Pictures Size 55.5,44x4 inch thick. Each soc. already now is your chance to get them, as Size 4y43'4x544x inch thick. Each 30c. they probably will be snapped up very quickly. Motion Picture Machines bought and sold; Send sufficient amount for postage. Electro Experimenter Publishing Co., 233 Fulton St., bargain lists free. National Equipment Com- Importing Co., zit Fulton St., N. Y. C. New York City. pany, Duluth, Minnesota. You benefit by mentioning the "Electrical Experimenter" when writing to advertisers.

www.americanradiohistory.com 288 ELECTRICAL EXPERIMENTER August, 1918

al1NlhluJIIlI11IIIuilWINIlliffi ImlImIIIImnhNU0n10uunfnlmmuumwinIUUmWWlluuun llillllilWWII1;IIIliIILJW lillllllllllllllllllllllllll ìill IIIIIIIIIIIIWIIIIIII IIIIIIIII IIIWIIIIIII IIIIIIiWIL'711IWIWll itUWUmIWUWUUnuuWllIIWIIIIIUlWUWEI UIWIWI81llW1W!WWIIWIIIIIIWIWilli lj Patent Attorneys Scenery for Hire Motorcycles Your Idea Wanted, Patent Your Invention. Collapsible Scenery for all Plays. Amelia Motorcycles From $25 Up -New and second- I'll help you market it. Send for 4 free books, Grain, Philadelphia, Pennsylvania. hand. Easy terms, large list to choose from, all list of patent buyers, hundreds of ideas wanted, makes. Send 4c wim1 munumi WlsintWmIIInWIIInuritirmr ImIIWIIIIIIIIInnumWIIIIumunImm numIIIW stamps for Bulletin "A." Peer- etc. Advice free. Patent advertised free. less Motorcycle Co., Watertown, Mass. Richard B. Owen, Patent Lawyer, 130 Owen Stamps and Coins EMINImlmWIIIIIIIIIIIIIIIIIIIIIIImiliiininil011NIIIIIIIIII10111WIIIluiIIOII8111uullhjl01111 Washington, D. C., or 2278 -T Woolworth un Bldg.,dg, New Yo Stamps --61 all different, free. Postage $c. News Correspondents Mention paper. Quaker Stamp Co., Toledo, Ohio. Patents on Easy Payments. Send model or Earn $25 Weekly, spare time, writing for sketch for Free Search and Certified Registra- 500 Finely Mixed United States or Foreign newspapers, magazines. Experience unneces- Stamps, 12c. Philatelic tion of Your Invention for Your Protection. Star, Madison, N. Y. sary; details free. Press Syndicate, 566 St. Free Book Tells What to Invent and How to Stamps -ta different from warring nations, Louis, Mo. Obtain a Patent on Easy Payments. C. C. roc. io different foreign coins, zsc; 3o Sweden llmlmlm IIIWIIIgIIIIIIWIIIIIIIIllmmlllm101mmIIINIWmIIIIl0111IIIIIlIIN01111110I0111nIImsnW ®ml Hines & Co., 593 Loan & Trust Bldg., Washing- Stamps, roc. Lists free. Toledo Stamp Co., ton. D. C. Toledo, Ohio. Watches California Gold Quarter Size, 27c; Half- dollar Expert Watch Repairing. Reducen Prices. Millions Spent Annually for Ideas! Hundreds References. now wanted! Patent yours and profit! Write size, 53c Dollar size, $1.io; Large cent, i82o, Leo Hirsh, Elkhart, Ind. today for free books -tell how to protect your- and catalogue roc. Norman Shultz, Kings City, IW umummimIIWIIWIImIIIIIIImIMiainWIIW1IWIWIIIWIIUIII1111111111WIIIenInnilumm self, how to invent, ideas wanted, how we help Mo. Miscellaneous you sell, etc. 212 Patent Dept., American In- imnmulmmmllu i f ommlm!mmltWWrnl mlmmnWMllumllmmulllnuiWIIWIIWmJII dustries, Inc., Washington, D. C. Telegraphy Japanese Aeroperfume; Produce most de- lightful fragrance. Latest sensation, asc; other York desirous Prominent New business men Telegraphy-Both MORSE AND WIRELESS; Japanese Novelties; List Free. D. Wooyeno, financing meritorious inventions protected by 217 W. zzsth Street, New York. me. Send me your ideas. Honest advice and STATION AGENCY taught quickly. THE MENDOUS DEMAND-greater than supply. For Sale Goodell 7 -in. x as in. Lathe, Compound 'Truth About Patents" free. J. Reaney Kelly, Slide Rest and 912 -D Woodward Bldg., Washington, D. C. PERMANENT POSITLONS SECURED -BIG Countershaft. Uninjured. SALARIES. IDEAL WORKING CONDITIONS. Price $30. Address The Stanley Company, 7g natiumunilnlml ullimmlluniumir ImIIItimiIIIIIIIIIIIIIIIIIIIIIIIWWIIIIIIIIIIUIfllllllllmmm GREAT OPPORTUNITIES FOR ADVANCE- Milk St., Boston, Mass. Phonographs MENT. WOMEN OPERATORS also needed. Tdbacco or Snuff Habit Cured or no pay. All expenses low -can earn living while attend- $1m if cured. Remedy sent on trial. Superba ing. Oldest and largest school- established 44 Co., SA, Baltimore, Md. Build Your Own Phonographs and manufacture years. Endorsed by Railway, Western Union Pyorrhea E. them for profit. Drawing instructions, Parts, and Marconi officials. Now offering special three -H. Kelty, D. D. S., M. D., pyor- Price List, Blue Print, etc., complete, sent free Radio rhea specialist for Is years, has developed a months' course for young men subject to successful home treatment upon request. Write today. Associated Phono- draft, enabling them to enter Signal Corps for pyorrhea. Puri- graph Co., Dept. E -z, Cincinnati. PREFERRED SERVICE." Large illustrated- fying, healing, preventative. Full month's treat- catalogue free. Correspondence ment and booklet $z. Circular free. Dr, H. E. Build Your Phonograph. "Perfection" high courses also. Kelty. Glenwood and Woodland Aves., Leonia, Write today. ENROLL IMMEDIATELY. N. J. quality spring and electric Motors, Tone Arms, DODGE'S INSTITUTE, Lone St., Valparaiso, Reproducers. Wonderful results, big saving. Indiana. We Have a limited number of beautiful art Handsome new catalog free. Indiana Phono- pictures on hand of Nikola Tesla and Dr. Lee graph Supply, Indianapolis, Ind. IIIImlll UmwinglllllllmmmlmIpmmmlmlmmmnnnlmmmmnnmmlmmlmmllmnimlmnmi Tricks, and De Forest. These make a handsome decoration lmlmusionammulmlmmminmllmon1811111nIIIImIIWIIWim mIIIIIIIIIIUIUImunmumo Puzzles Garnes for any laboratory or workshop and should be prominently displayed. Price for both, prepaid, Song Poems Wanted 1000 Stage Tricks with sop illustrations. Cata- loc. Experimenter Pub. Co., 233 Fulton St., log IOC. Small Catalog FREE. Hornmann Magic New York City. Co., Sta. 6, 67o Eighth Ave., New Write the Words for a Song. We write music York. "Opportunity Ad- Lets" bring quick results. and guarantee publisher's acceptance. Submit Tricks, Puzzles, Jokes, Toys, Games, Novelties, Over loo,000 circulation, net. Other firms are poems on war, love or any subject. Chester Doll and Cane Racks, Plays, Wigs, Stage Sup- making money -so can you. For proof address Music Co., 538 S. Dearborn St., Suite 265, Chi- plies, Escapes and .Illusions. Large 1917 catalog Classified Department Electrical Experimenter, cago. free. Oaks Magical Co., Dept. so, Oshkosh, Wis. 233 Fulton St., New ]fork City.

Scientific Exchange Columns undoubtedly have something you'd like to buy, sell or exchange. In your attic, or workshop, or some far corner of your closet, you un- YOUdoubtedly have dozens of long -forgotten articles useless to you now, but very useful to someone else. Live readers with something to "swap" or sell have found that the surest and quickest way to make the desired trade is thru an. ad in these columns. And remember that the U. S. Postal Laws protect you. No one can "do" or cheat you. Of 3,495 "ads" published in these columns during the past five years, only twelve complaints were reported to us, and each one was adjusted to the full satisfaction of the complainant. Deal- ers' advertising accepted in Opportunity Ad -let columns only. The rates are: Five cents per wort (name and address to be counted). Remittance must accompany alt orders. No advertisement for less than 50c accepted. We reserve the right to refuse any advertisement which we consider misleading or objectionable. Advertisements for the Sept issue should reach us not later than July 22. OVER 100,000 CIRCULATION GUARANTEED, A. B. C. AUDIT

For Sale -is dial Omnigraph, other things. Transactions of the Amer. Inst. of Electr. Typewriter-L. C. Smith, No. 2, for $25. Prac- A. Hersee, Burlington, Ontario. Eng. from 1916 and 1917 wanted for Stein - tically new. Clarence Osborn, g7 Watkins Ave., Sell or Exchange- Electrical apparatus for metz's Books or cash. Danubian, 2751 St. Vin- Middletown, N. Y. Hawkins Guides. Write. Robert Mueller, So. cent Ave., St. Louis, Mo. For Sale-Chemical laboratory consisting of 36 St. Paul, Minn. For Sale -H'lo Bugs; Am. Goin -a Join the chemicals and 28 pieces apparatus. Want good Bargain -Two $25 Stewart Speedometers used Colors. Who wants my station CHEAP. If its Omnigraph. Harry Ridings, Clarence, Mo. two seasons $10 each, and $as bicycle used very Wireless or Telegraph apparatus you want Wanted-Miniature electric locomotives, cars, little $io. Merrill Love, Emerald, Wis. say so quick, I have it. Answer all letters. and tracks. Locomotive any condition, any Sell separate. G. R. Smathers, 403 N. Brevard St., For Sale -5,36 Messano. Want $zo. Eugene make. Malone, 1539 Bryan Ave., S. W., Canton, Campbell, 12th St., Newcastle, Ind. Charlotte, N. C. Ohio. For Sale-rio V. Iron and stove; parts of tele- Enimmummoummoomminimmounimuninera Storage Batteries-6-4o each, $$y; large X -Ray phone- magneto, ringer, etc.; two private tele- tube, $6; $8 Audion panel, $3; No. 55 Murdock's phones with wire; 26 oz. Enameled and 6'A oz. 151 Lake Ave., $3.50 telephone ringer, Soc. Wanted, good sensi- of S. C. C. Copper wire No. 36; 36 ft. Tennis net; Lancaster, N. Y. tive relay. Frank A. Gillespie, Garden City, stamp album; needles for a wood burning set. Gentlemen: Kan sas. Articles sacrificed. Act quickly. Alon Shew. I wish to tell you that my ad, in the First Money Orders take these: 3 H.P. Motor- man, Tionesta, Pa. E. E. was a great success, and es- cycle engine, $1 4 volt t2o ampere storage For Sale -Large Radio Cabinet, 6o mile send- ceeded all expectations. I had replies battery, $to. Yt H.P. no v. i800 r.p.m. motor. ing, boo mile receiving, marbel panel operated. before I had received a copy of the George Conlin, 851 Columbus Ave., New York issue myself. This goes to show that City. Great sacrifice, $to. Value $r5o. (Trade.) L. A. for Hamilton, 378 Fairmont Ave., Oakland, Cal. every issue isi looked with great Bargains -Boy's Books, Meccano 3, Baseman's interest, and the wide field your paper A 24 -in Speedmore Bicycle in good condition Mitt. Description for stamp. W. Ware, Hamp- covers. I certainly will recommend H. except one tire. A real bargain at $16. Would to ton, N. swap. Reesor, it the amateurs that have something Delbert Lacenter, Ky. to trade or sell. For Sale -54 H. P. no or tao volt A. C. motor, For Sale-517.5o navy type coupler, never used, Yours respectfully, $15. 3 H. P. steam engine, $15. Lawrence De Sta. i K.W. E. I. Co. condenser, $3. Edw. C. W HADFO D. Palma, 542 Lobinger Ave., Braddock, Pa. Schurch. Deer Lodge, Montana. Bx Wanted -Astronomical Telescope and copies Wanted -Some new type Monotone Quenched Modern Electrics. Sell V. P. Kodak, $4.ro. Ed- gaps. Must be in first -class condition. Please For Sale -Light weight Pope motorcycle, $5o win Puls, Hoskins, Nebr. state your price. A. B. Farrow, Box 1548, Miami, Ariz. or what have you to exchange? De Boise For Sale or Exchange-Delco Motor-Generator Brewer, 6.o Prairie Ave., Beloit, Wis. self starter and ignition system; six no V. D. C. WANTED -High Power sending apparatus. CHEAP-$1.25 Wireless including goo M re- Motors; numerous electrical apparatus. Ex- Audion receiving apparatus. Full particulars in ceiving and K. W. sending. Also $50 miscel- change for bench lathe, screw cutting .preferred, first letter. Forrest Campbell, 317 Clifton Ave., laneous. What have you? Beckett Howorth, or what have you? Neal Brown, 242 East rink

Newark, N. J. West Point, Miss. St., New - York. You benefit by mentioning the "Electrical Experimenter" when writing to advertisers.

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10 Volumes HAWKINS AWlü9S Ettci8lf IEUN 3500 Flexible CqIDE:-- GUIDE Pages Covers 4700 `N1.-" Pictures Handy MODERN EIICrA1CITY ; - MARAÇN(ME WIRING A.C. MACIrtTISM LTEfi AIIK1 WIRING . TELELRAfR ARUCAIIOI Pocket - ` DYÑANOS' OISTRIBUOD INDUCTION POWER WIREEESS $1P"Volume ; SYSTLMS: CURRENTS trnA7PtNlf MOTORS STATIONS IIEpMICÌi?' . f1ElL5 Size ¡AStRÚME ' StORAGE, TEUPNOAL REF DYNynos ' ; ALTERNATORS ¡-FENCE $1. Per aRMNNR65 ULÑTING TESTING y. tBATI[RIES. WORK. C INDEX, Volumes wIM01X5 _ Month

Just what you need to know to succeed in ELECTRICITY every mechanic should know EVERY electrician, every engineer, READ THIS PARTIAL LIST OF CONTENTS about these wonderfully helpful instructive books, which give in Contains 348 pages, 388 Illustration& Electrical engi- No. 1 signs and symbols- static and current electricity plain words a complete working knowledge of electrical -primary cells-conductors and insulators -resistance and neering in all its phases. conductivity- magnetism- Induction coils- dynamo principles -classes of dynamos- armatures -windings- commutation- You run into some new electrical problem almost every day. The brushes. etc. Contains 348 pages, 394 Illustrations. Motor information you need to help you in your every day work is in No. 2 principles- armature reaction -motor starting - calculations -brake horsepower-selection and installation of dynamo and motors -galvanometers- standard cells -- current measurement - resistance measurement - voltmeters - watt- meters-watt boue metersperation of dynamos -operation motors, etc. Contains 300 pages. 423 illustrations. Distribution No. 3 systems -wires and wire calculations- Inside, outside and underground wiring -sign flashers -lightning pro- HAWKINS tection- rectifiers storage -- battery system, etc. 4 Contains 270 pages. 379 Illustrations. Alternating ELECTRICAL GUIDES No. current principles- alternating current diagram. -the power factor-alternator principle.- alternator con- These books place electricity at your finger ends. They cover every imaginable struction-windings. etc. subject, principle, theory, problem, trouble, and way of doing things electrically. 5 Contains 320 pages, 614 Illustrations. A. C. Motors Every subject is indexed so that you can turn right to it. They are a study course No -synchronous andinduction motor pHOclples-A. C. and a reference guide in one, written in plain every day language -no wasted words commutator motors- induction motors, transformers; losse.. what you need to know full of -'he- minute knowledge. construction. connections, tests-converters-rectifiers. etc. -only -chock upto electrical Contains 298 pages. The guides are a complete course in electrical engineering. They will help in NO. 6 472 illustrations. Alternating you current systems -switching devices-circuit break - every detail of the day's electrical work. You can't ask an electrical question that era-relays -lightning protector apparatus- regulating devices Hawkins Guides can't answer. -synchronous condensers- Indicating devices -meters-power factor Indicators -wave form measurement -switch boards, etc, Contains 316 pages, 379 illustrations. Alternating NO. 7 current. wiring power stations-turbine.; manage- Pocket -Size Flexible Covers ment, selection, location, erection, testing, running care and repair-telephones, The books are small enough to slip Into your coat etc. pocket-handsomely hound in flexible black r ers. No. 8 Contains 332 pages. 436 Illustrations. Telegraph What Electrical Men Say You can carry each volume with you untile you bave - simultaneousne us telegraphy and telephony rele.s --el ectric bells-electric - Helped Him Make Good mastered its contents. 3,500 pages of actual information lichons-PM1nmmetry . etc. and 4.700 illustrations. -,Once you see these books and NO. 9 Cic 322 pages, 627 Illustrations. ght-- "It Is only right for me to recom- put them into actual us _ u will never again want to be [ar railways-electric[pirwaos- electric locomotives-earapes -rev ngbt- mend highly the Hawkins Guides. for without them. Try It at our expanse. cyrev s& ngine mobraunnf they have blen of the greatest assist- starter engines.ignition-automobile te.f- ance to me in plaoing me in my pres- rertere and lighting systems, elrrtricelectric vehicles, etc. ent position as Superintendent of Con - Contains 513 pages, 599 illustrations. truction Department of one of Ohio's NO. 10 Elevators-cranes -pumps -air com- largest Electrical Companies. I would SEND NO MONEY pressors- electric heating - electric welding like to see every man have set of soldering and brazing- Industrial electro- THEO. Hawkins Guides." It will cost you nothing to receive these books -to look lysis- eeectro plating -electro- therapeutic AUDEL & Co. Geo. Knecht, Columbus. Ohio. them over-ask them all the questions you can think of -S -rays, etc. 72 Fifth Avenue -use them in your work-study them -ruck up some In- Also a complete 126 -page ready In the Naval Electrical Dept. formation that will increase your earning ability. We # New York, N. Y. will ship you the entire set of 10 volumes entirely FREE. reference index of the complete "The Hawkins Guides are great help This is a sign of our confidence in the guides. }lure library. This index has been [lease submit use for to me In the Naval Electrical Depart- does not object to examination It w k I n a ment, which very gold being tested. Keep them for planned to render easily ac- a they cover thorough- seven vs and if you do not decide that you can't get cessible , Electrical Guides (p r I e ly." C. J. Cornell. all the vast infor- along without them, return them to us and Ave us motion in $t each). Ship at once. pro - tl. S. Receiving Ship, Brooklyn, N. Y. nothing. contained the the 10 numbers. If eat- 10 electrical guides. raid. Superintendent When you decide to keep them you only have to Day I agree to send you $1.00 down and remit the balance of $3.00 on the easy There are over 13; withinthin seven days and to further 'I am now superintendent of the Payment of $1.00 a month till paid for. 500 cross refer- mail you El each month until paid. Dunnville Hydro - Electric Systems. Use this coupon to get the hooks. It will pay you coces. You find d , Itawklne Guide. were great help many times over. to me in bolding down a responsible what you want signature position." to know in- W. E. stantly. Swartz, Dunnville, Ontario. THEO. AUDEL & CO. Occupation Wireless Operators "I have worked wireless for ten 72 Fifth Ave. New York, N. Y. Business AdCress years -but I wish I had these books years ago. as they have saved me a great deal of trouble." 11. Marshall Residence Steamer M & 13 No, 2. 41, Walkervllle, or;, SEND NO MONEY- USE THE COUPON- Reference E. Aug. Yon benefit by mentioning the "Electrical Experimenter" when writing to advertisers.

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