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44-1 Cass Street

Chicago, III.

9

May, 1918 xS^vO ELECTRICAL EXPERIMENTER 1

EXPERIMENTERS !

No. EX2002

<<r-pVHB BOY'S ELECTRIC TOYS" contains enough mate- 1 rial TO MAKE AND COMPLETE OVER TWENTY- -1- FIVE DIFFERENT ELECTRICAL APPARATUS with- out any other tools, except a screw-driver furtjished with the outfit. The box contains the following complete instruments and apparatus which are already assembled :

Student's chromic plunge battery, compass-galvanometer, solenoid, telephone receiver, electric lamp. Enough various parts, wire, etc., arc furnished to make the following apparatus:

Electromagnet, electric cannon, magnetic pictures, dancing spiral, electric hammer, galvanometer, voltmeter, hook for telephone receiver, condenser, sensitive microphone, short distance wireless telephone, test storage battery, shocking coil, complete telegraph set, electric riveting machine, electric buz- zer, dancing fishes, singing telephone, mysterious dancing man, electric jump- ing jack, magnetic geometric figures, rheostat, erratic pendulum, electric but- terfly, thermo electric motor, visual telegraph, etc., etc

This does not by any means exhaust the list, but a great many more ap- paratus can be built actually and effectually.

With the instruction book which we furnish, one hundred experiments that can be made with this outfit are listed, nearly all of these being illustrated with superb illustrations. No other materials, goods or supplies are neces- sary to perform any of the one hundred experiments or to make any of the 25 apparatus. Everything can be constructed and accomplished by means of this outfit, two hands, and a screw-driver.

The outfit contains 114 separate pieces of material and 24 pieces of finished articles ready to use at once.

Among the finished material the following parts are included: Chromic salts for battery, lamp socket, bottle of mercury, core wire (two different lengths), a bottle of iron filings, three spools of wire, carbons, a quantity of machine screws, flexible cord, two wood bases, glass plate, paraffine paper, binding posts, screw-driver, etc., etc. The instruction book is so clear that anyone can make the apparatus without trouble, and besides a section of the instruction book is taken up with the fundamentals of electricity to acquaint the layman with all important facts in electricity in a simple manner. We guarantee satisfaction.

The size over all of the outfit is 14 x 9 x 2%. Shipping weight, 8 lbs, CC nn

. No. EX2002 "The Boy's Electric Toys." outfit as described <|>J.UU

L IMMEDIATE SHIPMENTS

231 Fulton St. NEW YORK

ELECTRO IMPORTING CO.,

Student's Chromic Plunge Battery

This is :in ideal bat mental work where a not required. This b; lamp fur several hour run a small toy motor

cry for electrical experi- jery powerful current is Uery will hunt a 2 volt on one charge; it will surprisingly well ; it will

lectroplaung work; it is ideal lor testing work; it gives a fairly steady current, and as the zinc electrode can be pulled clear of the electrolyte, no materials are used when bat- tery stands Idle.

Best Amalgam Zinc only is used, as well as a highly porous carbon to ensure a steadier current. We furnish enough chromic salts for

arges. Full directions for operation and care of battery are included.

battery tests 2 volts and (i amperes when set up fresh. Not over 2 res should be drawn from battery continuously. By using six or eight ese batteries, a great many experiments can be performed. No solution run out of this battery if 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 Plunge Battery

IMMEDIATE SHIPMENTS

$0.50

The "Electro" Radiotone

HIGH FREQUENCY SILENT TEST BUZZER

This instrument gives a wonderful high pitched MUSICAL NOTE in the receivers, impossible to obtain with the ordinary test buzzer. The RADIOTONE is built along entirely new lines; it is NOT an ordinary buzzer, reconstructed in some manner. The RADIOTONE has a single fine steel reed vibrating at a remarkably high speed, adjusted to its most, efficient frequency at the factory. Hard silver con- tacts are used to make the instrument last practically forever.

Yes. the RADIOTONE is SILENT. In fact, it is so silent that you must place your ear on top of it to hear its beautiful musical note.

You will be astounded at the wonderfully clear. 500 cycle note, sounding sharply in your receivers. To learn the codes, there Is absolutely nothing like It. With the radiotone. a key and one dry cell and ANY telephone, a fine learner's set is had. Two or more such sets in series will afford no end of pleasure for intercommunication work. Shipping Weight I Ib.^

Radiotone as described each S| Mil

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is not a toy. but a practical, honestly built telegraph outfit, which not only sounds but works like the big commercial instru- ments. By studying the code for 30 days you can become a first-class telegraph operator. Such operators are in big de- mand now. Outfit consists of TWO complete telegraph instru- ments each measuring ?,y2 x 2% x 2V±. All metal parts are high- ly nickel plated, including key lever. Note hard rubber knob. Telegraph Code Chart, telegraph ilanks and connecting wire comes with set, hut 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 switches, no extras. Nothing to get out of order. Guaranteed to please you or money back. Price Complete as illustrated (TWO INSTRUMENTS)..

Shipping Weight, 2 lbs. IMMEDIATE SHIPMENTS

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The "Electro" Codophone (Patents Pending)

What this ftl SO

r e m arkable ^■^iF I«UV

instrument Is ~~ and does.

The "Elec- tro" Codo- phone is

positively the only instru- ment m a d e .that will imitate a 500 cycle note exactly as heard in a V7ireiess re- ceiver. T h e

loud-talking receiver equipped n the sound all over the room, eve

THAT'S NOT ALL. By less from the lowest, softest quality sound can be had in a few seconds.

FOR INTERCOMMUNICATION, ment. two Codophones when connec can be used for intercommunication belween two houses

One outfit alone replaces the old-fashioned learner's sisting of key and sounder.

The "Electro" Codophone is a handsome, well made instrument, fool proof, and built for hard work. Contacts are of hard silver y8 inch in diameter, that will outlast the instrument.

There is also a neat code chari and full directions enabling any intelli- gent young man or girl to learn the codes within 30 days, practising one- half hour a day.

Sizes: 6% x 3 x 2%". Shipping weight. 2 lb; The "Electro" Codophone as described, complete.

th a horn, talks so loud that you can hear

if there is a lot of other noise, ling or tightening the receiver cap, a tone

up to the loudest and highest screaming

Csing ted wi

dry cell

for each instru- 1 return ground, ne-half mile apart, telegraph set, con-

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I i nclose herewith 6 cents in stamps or coin for which please send me your latest Cyclopedia Cata- log No. 10 as described.

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2

ELECTRICAL EXPERIMENTER

May, 1918

AVIATION MECHANICS

Needed for New Positions

Thousands of splendid new positions now opening up everywhere in this amazing new field. New Airplane factories being built — automobile and other plants in all parts of the country being converted to turn out vast fleets of Airplanes for our armies in Europe. And only a few hundred ex- pert Airplane Mechanics available, although thousands are needed. And this is only the beginning. Already airplane mail routes are being planned for after the war and thousands upon thousands of flying machines will be wanted for express and passenger carrying service.

Not in a hundred years has any field of endeavor held out such wonderful chances to young men as are offered to you today in the Aviation Industry. Resolve now to change your poorly paid job for a big paying position with a brilliant future. Send the cou- pon today for Special limited offer in Practical Aeronautics and the Science of Aviation and prepare yourself in a few short months to double or treble your present salary.

We Teach You By Mail

IN YOUR SPARE TIME AT HOME

What Our Students Say: Mr. Stanfield Fries

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Mr. Z. Purdy Shreveport, La. It is hard to believe that lessons on such a subject could be gotten up in such an interesting manner.

Mr. Lloyd Royer Haigler, Neb. I can hardly thank you enough for the way you have personally taken up my enrollment.

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Earn $50 to $300 per week as

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Our new. scientific Course has the endorsement of airplane manu- facturers, aeronautical experts, aviators and leading aero clubs. Every Lesson, Lecture, Blue-Print and Bulletin is self-explanatory. * You can't fail to learn. No book study. No schooling required. M Lessons are written in non-technical, easy-to-understand language. » You'll not have the slightest difficulty in mastering them. The /

Course is absolutely authoritative and right down to the minute y Without any obligations in every respect. Covers the entire field of Practical Aeronau- ' on my part, you may send tics and Science of Aviation in a thorough practical manner. Under our expert direction, you i me full particulars of your

get just the kind of practical training you must have in order to succeed in this wonderful £ >•; > r sen ,il U > p

American School of Aviation

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Dept. 7445 Chicago, Illinois

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Tt ;<= nnr duty to help in every possible way to supply the urgent need for graduates of this great school We have facilities for teaching a few more students, and to secure them quickly we are makine a remarkable Special Offer which will be withdrawn without notice. Write today— or send the coupon— for full particulars. Don't risk delay. Do it now.

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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. 61

MAY, 1918

No. 1

TELEVISION AND THE TELEPHOT Front Cover

From a painting by Vincent Lynch ELECTRICITY AND CAMERA GIVE 3,000,000 SHELLS THIRD

DEGREE 5

LOCATING AND DESTROYING "SUBS" WITH ELECTRO- MAGNETS 6

YANKEE CODE NOT SO "BLOEDSINNIG" 7

NEW SPY AND SCIENTIFIC MOVIES By George Holmes 8

ELECTRICITY AND METAL COATED SEEDS BOOST CROPS... 9

THE ELECTRO-MAGNET IN THE OPERATING ROOM

By S. Gernsback 10

/TELEVISION AND THE TELEPHOT By H. Gernsback 12

ELECTRICALLY HEATED BEDS FOR THE WOUNDED 14

A NEW PHONOGRAPHIC LOUD-TALKER. . .By H. WinfTeld Secor 15

"VOL. VI— No. 1"

"SUB"- DETECTOR, THRILLER IN NEW WAR PLAY 18

SCIENTIFIC RESEARCH ESSENTIAL TO HUMAN PROGRESS

By Dr. Willis R. Whitney 19

MODERN AMERICAN ELECTRIC FURNACES

By Frank C. Perkins 20

ELECTRIC "SHERARDIZING" PREVENTS RUST 21

FIXATION OF NITROGEN BY ELECTRICITY

By Theodore Bodde

16

23

THE PHENOMENA OF ELECTRICAL CONDUCTION IN GASES

By Rogers D. Rusk, M.A. 25

RADIO DEPARTMENT 26

EXTERNAL GRID VACUUM VALVE CONSTRUCTION

By R. U. Clark— 3rd 28

THE HOW AND WHY OF RADIO APPARATUS

Lesson 8 — By H. Winfield Secor, Assoc. I. R. E. 30

DESIGN FOR A PANEL TRANSMITTING SET

By James R. Hopkins 31 THEORY OF TUNING, WAVE LENGTHS AND HARMONICS. .. .

By Prof. F. E. Austin 32

BUILDING AN ELECTRIC PIANO PLAYER By Charles Horton 34

EXPERIMENTAL MECHANICS Lesson 3— By Samuel Cohen 36

"SHOOTING" ELECTRICAL TROUBLES ON AUTOMOBILES....

By Thomas W. Benjamin 38

A TIGHT SQUEEZE FOR UNCLE GEORGE By Thomas Reed 39

HOW-TO-MAKE IT PRIZE CONTEST 40

WRINKLES, RECIPES AND FORMULAS .... Edited by S. Gernsback 41

EXPERIMENTAL CHEMISTRY

Lesson 24 — By Albert W. Wilsdon 42

WITH THE AMATEURS PRIZE CONTEST. 43

LATEST PATENTS 44

PHONEY PATENTS— CONTEST t. 45

"THE ORACLE" 46

LIBRARY

WINNING THE WAR

HIS war, more so than any other, is a machine war. A stereotyped phrase, but, nevertheless, a very true one. When we speak of a machine war, we usually have in mind artillery of all calibres, from machine guns upwards to 42 cm. guns, and larger.

We believe that we will not be contradicted when we state that vast bodies of infantry can not move forward nowadays without the support of protecting artillery from its rear. Logically, the conclusion follows that if we can annihilate the enemy's artillery, he must fall back. Even trench systems without artillery support from the rear can not be held for any length of time by the enemy. If our artillery is intact, but if the enemy is deprived of his, even tho his infantry should outnumber ours ten to one, he would have to retreat just the same. These, of course, are very obvious facts.

The British now engaged in the Western war theater realized this truth very early and set about to rectify it. The result was their present Tanks. These machines fulfill several purposes ; they are used to batter down the barbed wire entanglements protecting front line trenches ; secondly, they raise havoc among the enemy's men by flank fire once across his lines, but most im- portant of all the Tanks are supposed to annihilate the enemy's artillery either by putting the artillerists out of action by gun fire from the Tank or by climbing right over the enemy's guns, thus putting them hors de combat. For the first two purposes the Tanks are ideal ; for the latter they have signally failed. The reason is very simple. The Tank is an extremely slow- moving vehicle in the open field — five to eight miles an hour at the most is its speed. Even if camouflaged, a Tank makes a shining mark for the enemy gunners, who find little trouble in getting the range of the slowly crawl- ing tractor. One or two shells soon puts the most am- bitious Tank out of business.

Ever since the Tank made its first appearance we have pointed out in many of our articles that on account of its ridiculously slow speed the machine as now built could never be a factor in modern warfare.

In other words, the large and speedy machine obvi-

ously is the thing in this war. In former articles we have shown that it is perfectly feasible to run monster machines over land at speeds from twenty miles upward. We have shown how our obsolete battleships could be readily equipt with huge channel-iron wheels to ride over land; we have also shown how 45-foot big- wheeled steel monsters, steered by gyroscopic means, could be used to run over the enemy's artillery, grinding it into the ground. And such monster machines would be practically immune to enemy shell fire on account of their high speed. The construction of these machines being largely open iron-channel work, even a direct shell hit would not do much damage, beyond ripping out a few steel pieces.

Strange to say, monsters of this kind would claim little toll of life; if you see such a juggernaut of death heading your way, you simply sidestep it ! Such ma- chines are not designed to kill ; they are used solely to destroy the enemy's guns, or putting them out of action.

Now the point we wish to make is that men alone will not win the war for us. The big machine is the thing. One such monster replaces several thousand men. The nation that can build the largest buildings on earth, that has the greatest mechanical resources of the Allies, can easily build these comparatively simple machines. They are feasible from an engineering stand- point. Most important of all, such machines can be readily sent to France knocked down. Five hundred of them could be sent to France with the same amount of tonnage it takes to send over 25,000 of our boys. Five hundred big monsters might decide the war for us quickly ; 25,000 men are a mere trifle in this war — they do not begin to make an impression.

A few weeks ago, if we had proposed a gun that could shoot 74 miles we would have been laughed at scornfully. It would have been one of our "pipe dreams." The trouble with us Americans is that we don't "dream" enough, while the Germans outdream us.

And if we do not get the big machines over to France soon, the Germans will surely beat us to it. Let us wake up.

H. Gernsback.

The ELECTRICAL EXPERIMENTER la publisht on the 15th of each month at 233 Fulton Street, New York. There are 12 numbers per year. Subscription price is $1.50 a year In U. S. and possessions. Canada and foreign countries, $2.00 a year. U. S. coin as well as U. S. stamps accepted (no foreign coins or stamps). Single copies, 15 cents each. A sample copy will be sent gratis on request. Checks and money orders should be drawn to order of EXPEE1MENTEB PUBLISHING CO.. INC. If you change your address notify UB promptly. In order that copies are not miscarried or lost. A green wrapper Indicates expiration. No copies sent after expiration.

All communications and contributions to this Journal should be addrest to: Editor. ELECTRICAL EXPERIMENTER, 233 Fulton Street, New York. Unaccepted contribu-

tions cannot be returned unless full postage has been included. ALL accepted contribu- tions are paid for on publication. A special rate is paid for novel experiments; good photographs accompanying them are highly desirable.

ELECTRICAL* EXPERIMENTER. Monthly. Entered as second-class matter at the New York Post Office under Act of Congress of March 3. 1879. Title registered U. S. Patent Office. Copyright. 1918. by B. P. Co., Inc.. New York. The Contents of this magazine are copyrighted and must not be reproduced without giving full credit to the publication.

The ELECTRICAL EXPERIMENTER is for sale at all newsstands in the United States and Canada; also at Brentano's. 37 Avenue de l'Opera. Paris.

4

ELECTRICAL EXPERIMENTER

May, 1918

LEARN BY DOING'

The Only Way to Learn Electricity

The only way you can become an expert is by doing the very work under competent instructors, which you will be called upon to do later on. In other words, learn by doing. That is the method of the New York Electrical School.

Five minutes of actual practice properly directed is worth more to a man than years and years of book study. Indeed, Actual Practice is the only training of value, and graduates of New York Electrical School have proved themselves to be the only men that are fully qualified to satisfy EVERY demand of the Electrical Profession.

At this "Learn by Doing" School a man acquires the art of Electrical Drafting ; the best business method and

experience in Electrical Contracting, together with the skill to install, operate and maintain all systems for pro- ducing, transmitting and using electricity. A school for Old and Young. Individual instruction.

No previous knowledge of electricity, mechanics or mathematics is necessary to take this electrical course. You can begin the course now and by steady application prepare yourself in a short time. You will be taught by practical electrical experts with actual apparatus, under actual conditions. 5,000 of our students are today suc- cessful Electrical Practitioners. Come in and read their enthusiastic letters. Let us explain this course to you in person. Tf you can't call, send now for 64-page book — it's FREE to you. SCHOOL OPEN ALL SUMMER.

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H.GER.NSBACK - EDITQJfcj) H. W. S E C O R. - A//OCIATB EftETOR A,

Vol. VI. Whole No. 61

MAY, 1918

B " APR 17

rv

Number 1

Electricity and Camera Give 3,000,000 Shells Third Degree

HAVE you ever stopt to think just how the experts of the ordnance department of our own as well as foreign governments manage to check up the huge quantities of cannon shells shipt to the front? Possibly not, when the accompany- ing photos will give some idea of the ex- tremely fine electrical precision apparatus employed for the purpose, as well as the method used for safely firing faulty shells.

The photo at left illustrates the delicate electric chronograph, a highly sensitive and

electrically operated camera, the whole lot of 25,000 shells was immediately returned to the manufacturer.

The electric chronographs or split-second clocks used in timing the velocity of the shells when fired, are connected up to a net-work of electric wires placed at cer- tain predetermined intervals along the prov- ing range. Briefly explained the operation of the velocity test is as follows: As the bullet or shell leaves the muzzle of the gun it strikes one net-work of electric wires, severing one of the wires, which causes one

for exploding shells that have failed to go off when fired. The shells are recovered by "shell scouts" on the range and are fired off electrically by the officer in charge.

Photography played an important part in testing the 3,000,000 Russian shells at the Lakehurst proving grounds. It is said to be the first time that the electric camera was ever used in this country to determine the velocity of projectiles.

Right photo shows five of these re- markable instantaneous photos of shells in flight. These views show shells photo-

accurate electrical instrument used for re- cording the speed of shells in flight. This instrument showed the ordnance inspec- tors of the Russian Government that they were sending shrapnel shells thru the air at the rate of 1,950 feet per second !

These photos are all taken of a Russian test on American-made ammunition con- ducted at Lakehurst, N. J., where over 3,000,000 shells were tested. Each shell could not, of course, be tested so the in- spectors satisfied themselves with checking up sixty shells from every 25,000 pro- duced. If one shell when fired failed to register properly on the photo taken by the

of the electrically controlled split-second chronographs to be immediately actuated. The shell speeds on for say a thousand yards or so, depending upon the test and size of shell, when it strikes another net- work, severs a wire, opens the circuit of a second split-second chronograph and the deed is done. It is evident that by check- ing up the difference in time between the two (or more) chronographs and knowing the distance the shell traveled between both clock actuations, that the velocity of the shell in feet per second is at once deter- mined.

The steel pit at center, shown here, is

graphed in flight at different ranges in versts Russian measurement (one verst is 3,500 feet). Note the tiny dot lights at the bottom, right, left and center of each picture, also the cross-lines in the center photo, which are sometimes used to check the grouping of the shells while in flight as well as the area covered by bursting shrapnel. Shells to pass inspection have to show on the plate within the space marked by the right and left lights. The electrically controlled camera proved more trustworthy than the stop-watch. These twenty shells past the test. Similar instruments are in use by the U. S. Government experts.

5

6

ELECTRICAL EXPERIMENTER

May, 1918

Locating and Destroying "Subs" with Electro-Magnets

THERE'S one thing certain about this war anyway, and that is that there will be no falling off in the business of the patent office. Not if the Yankee inventors can help it, at any rate. For one thing they will be able to keep the patent examiners busy on anti- submarine devices for several years to come, apparently. We thought that the magnet schemes for combating the U-boat menace were about exhausted — we said "thought," but here's a new one. And it employs elec- tro-magnets— oodles of them if necessary. The inventor of this newest magnetic "Sub"

thru the danger zone, so that a large area may be covered in a predetermined time. A substantial base is secured rigidly upon the aft deck of the vessel as shown in the illus- tration herewith. This base preferably ex- tends beyond the line of the hull, as it is upon this base that most of the working parts of the device are mounted.

Pivoted at the rear end of the base is a rearwardly projecting, vertically swinging boom which is by preferance extensible and retractable, set screws or clamps being pro- vided for holding it in adjusted position. The rear end of the boom is forked as

at any suitable point on the ship, a genera- tor being provided for charging the battery to the required extent. The generator may either be driven from the internal mechan- ism of the ship, or from an individual motor or engine.

The two cables attached to the electro- ■ magnet are wound upon a drum suitably mounted upon the deck base, the anchored ends of the duplex electric feed cable, being past thru the hollow shaft of the drum and secured to a pair of contact rings which are insulated from the shaft, that is the two wires which comprise the feed cable, are

	SW/NG/NG BOOM ' '

FLOAT

^ DUPLEX EL ECTR/C CABLE

CONTACT W/MES

BRUSHES H TO MAGNET STEEL CABLE JKl

DUPLEX ELECTRIC CABLE ON REVOL VABLE DRUM PLACED ON DECK

As a General Rule the "Magnet" Schemes Proposed for Combating Submarines Are Worthless. This One Possesses at Least Some Sem- blance to a Practical Idea. An Inventor Recently Patented the "Magnetic Bomb" Scheme Illustrated. The Vessel Using the Device Trawls the Powerful Electro-Magnet Astern; When Its Cable Pulls Taut the Crew Knows They Have Landed a Submerged "Sub." Extra Electric or Magnetic Depth Bombs Are Lowered Into the Water, the Ship Moves Away a Suitable Distance, and the Rest Can Be Imagined.

destroyer is Mr. John A. Gault of Lan- caster, Wisconsin, and the modus operandi of his arrangement is as follows :

The invention has for its object to pro- vide efficient means whereby submarines may be located and destroyed, the invention consisting briefly of an electro-magnet, towed by means of a cable, beneath and in rear of a vessel, for locating submerged objects such as submarine vessels and mines, and means for lowering a bomb to destroy the submerged object when it is once entrapt by the magnet. The ship using this apparatus is preferably of the screw- driven type and driven as fast as practicable

shown, and a suitably shaped float is mounted pivotally in this fork, the float having formed there thru a guideway thru which a suitable steel cable and an electric wire cable pass slidably and at intervals are secured together by suitable clips, these clips being preferably disposed at prede- termined points so that they may be pro- vided with indicating members whereby the depth at which the magnet is located, may be readily determined, the magnet being car- ried by the lower end of the steel cable and supplied with electric current from the duplex electric cable. This current is sup- plied to the cable from a storage battery

secured to the brush rings. Suitable brushes contact with the rings, and current con- ducting wires lead from these brushes to the battery. It will thus be obvious that no matter how much the cables are wound or unwound, the current supply of the magnet will always be constant.

Any preferred means could be employed for raising and lowering the boom, but for illustrative purposes there is shown a spe- cial cable secured at its outer end to the free end of said boom, and wound at its other end on a winding drum mounted on the base.

(Continued on page 66)

May, 1918

ELECTRICAL EXPERIMENTER

7

Yankee Code Not So "Bloedsinnig"

WITH the American Expeditionary Army, France. — "I'll be in Oregon at 3. At 4 o'clock I'll be fixing up that ration question with Hinden- burg in London. And if you want me after that I'll be over in Tallahassee. Just ask for the Kaiser."

Not a quotation from the ravings of a mad man — nor "balmy in the 'ead," as our British friends are wont to call the chap who is a bit "loco" in his "attic."

The foregoing conversation is just one end of a typical 'phone talk on the front where everything is "code."

The young divisional supply officer was about to leave on a round of the fighting

This "code" is a safeguard against enemy "listening-in" sets. By means of induction — stringing wires parallel to our trenches, tho 50 yards away in "No Man's Land" — the wily Germans often pick up the Yankee talk over the wires. It therefore becomes plain that if a Boche listening post picked up that message the observer scanned his maps of the sector in vain for "London" and "Tallahassee." And "Hindenburg" — there's only one Hindenburg and he isn't visiting London these days to consult on rationing problems. Every loyal Boche knows that. The "bloedsinnige" (idiotic) Yankees must be mad.

It is an interesting fact that where tele-

distance circuits when they happened to be parallel one' another for any appreciable distance. Inductive effects were manifested between the telephone cables leading from New York City to Saratoga, N. Y., and Providence, R. I., due to the proximity of these two circuits in New York City.

The insert detail here shown gives the simple arrangement necessary for listening in by induction to conversations in a cer- tain telephone line. The listening post of the enemy may moreover be equipt with powerful amplifiers to intensify whatever messages are intercepted. Ordinarily it is only necessary to connect up a telephone receiver to the single "paralleling" wire.

Every Now and Then the Press War Reports Contain the Statement That the Enemy Has Been Caught "Listening In" to Telephone Con- versations, or Also That Enemy Telephone Lines Have Been "Listened In" On. Here's the Way It Can Be Done — Purely By Electrostatic Induction, Without Any Metallic Connections Between the Two Circuits. It is a Well Known Phenomenon to all Telephone Men.

points on the front. He was giving one of his subordinates instructions over the phone on how to reach him in case of need during the remainder of the afternoon.

"Oregon" is an artillery post a few kilo- meters from headquarters — not the Western State where the apples come from. Hinden- burg is a battalion commander whose right name may be Smith, and London is a dug- out in the support line "up front." After that he was going to a brigade headquar- ters. On the 'phone he answers to the name of "The Kaiser."

It's simple if you have the key, but a crazy confusion of far flung places and ir- reconcilable names if you don't know what they're talking about.

graph and telephone circuits or multiple telephone circuits only lie near each other for any appreciable distance then such cir- cuits are subject to electro-static inductive effects, which produces what is technically called "cross-talk." Telephone circuits are transposed to obviate this difficulty in prac- tise.

In one instance it was found (see Sewall's "Wireless Telegraphy") that where a wire was run along parallel to a telephone cir- cuit for 300 feet and at a distance of 30 feet on the average, the "talk" could be heard in a telephone receiver connected in the separate "listening circuit." In the early days of telegraphy great trouble was often experienced by "cross-talk" between long

This is usually a simple matter, as the trenches frequently run nearly parallel for considerable distances. The listening wire should, of course, be insulated and part of it might be camouflaged or hidden in the dirt of "No Man's Land," so as to reduce the distance between the two circuits, and thus increasing the inductive effect. In some instances the telephone lines have been but a few feet apart.

An early American radio-worker, one Amos E. Dolbear, invented and patented an inductive telephone and telegraph sys- tem and actually made it "talk" one-half mile. His patent was issued in 1886, but owing to the limitations of such a system (Continued on page 66)

8

ELECTRICAL EXPERIMENTER

May, 1918

New Spy and Scientific Movies

THERE seems to be no dearth of in- teresting photoplays, especially among those that depend on science to at- tract theater patrons. One film-play in particular is very much in the limelight at present, being the expose of numerous plots against the United States even before we were drawn into this great world conflict.

Written by that celebrated authority, Wm. J. Flynn, late retired chief of the U. S. Secret Service, the drama under the title of

"The Eagle's Eye" leads one thru a series of episodes which show the despicable methods and plots originated to wreak ven- geance and hamper as much as possible the work of beating the "Hun" !

Two of the photos show a specially built wireless-controlled torpedo which the Im- perial German Government made in this country for the destruction of the flagship of the Atlantic Fleet as it was leaving New York Harbor after the review of 1915. Also there may be seen a compact' land radio set tuned with the apparatus on the torpedo, so that perfect control may be had.

By GEORGE HOLMES

Another photo shows an exciting scene in the sixth episode of "A Daughter of Uncle Sam." Jessie Emerson (Miss Jane Vance) has just been captured by a band of German spies and taken to their head- quarters in an abandoned cave on the New England coast, where they propose to force her to reveal the secret of a marvelous war invention perfected by a lieutenant in the United States Army. Jessie pretends to faint and while her guard rushes for aid she makes her way to the wireless instru-

ment in the cave and sends out a call for help. The ruse is detected and she is over- powered, but not before the operator who has taken her place at the Government sta- tion has picked up the brief message. The unfinished call for help is turned over to the army authorities, and soldiers are or- dered to scour the community in search of the possible hiding place of the gang.

The last photo is a laboratory scene from "The Light Within," a recent Petrova photo-play feature. Mme. Petrova, the famous Polish star, plays the part of I aurel. a doctor's daughter, who, in order

to get money to complete her father's scientific researches, marries a wealthy man she doesn't love. A son is born to the couple only to become a barrier between them. The husband leaves for a long sea trip, is reported lost, but turns up at home just in time to see Laurel promise herself to Richard Leslie, a young doctor she had loved before her marriage. The death of their son embitters Durand, the husband, and he plans a revenge as fiendish as it is novel.

He pretends a deep interest in the young doctor and thru various pretexts throws the pair together on every conceivable oc- casion. Laurel finally discovers a serum for the cure of the deadly anthrax germ thru the medium of the mascarine turtle. She possesses but one small specimen of the turtle, the only other one being the property of the city Zoo. Supremely con- fident of the serum, she decides to demon- strate the efficacy of her cure for anthrax by inoculating herself with the deadly poison. Young Leslie begs her to use him {Continued on page 66.)

War Plots, Science, Mystery — All Are Dished Up in Profusion in the Newest "Movie" Dramas. Fig. 1 — A German Spy Radio Station In the Mountains, from "A Daughter of Uncle Sam." 2 — The Chemical Laboratory in Olga Petrova's "The Light Within." Figs. 3 and 4 — A New Radio-Controlled Torpedo Built by German Spies in America, from "The Eagle's Eye."

May, 1918

ELECTRICAL EXPERIMENTER

9

Electricity and Metal Coated Seeds Boost Crops

ELECTRICITY at high potentials has been used heretofore in an effort to stimulate the germination and growth of plant life, particularly those of a food-bearing nature. Several English experimental farms have been trying out such schemes with more or less success, but apparently the method used whereby several hundred thousand volts of high frequency current is caused to "leak off" an elevated wire net-work to the plants themselves, left considerable room for improvement.

This improvement seems to have been made by a Chicago, 111., genius, Mr. Robert D. McCreery, who has provided a truly

r

. EUCTROpE

I Currents Pass Thru g^pleta^artlcje^n^arth

novel scheme whereby the high potential, high frequency currents do not have to tra- verse several million ohms of "air resist- ance" before reaching the plants, but are enabled to pass thru the earth directly to the roots of the growing plants or to the seeds undergoing the process of germina- tion. An increase of 30 per cent and more was attained in the crop production as proved by actual "growing" tests.

"Electricity," declares Mr. McCreery, "unquestionably stimulates seed germina- tion and subsequent plant growth. Electri- city in the soil causes larger crops and healthier plant life. With the end in view of stimulating food crops in England at a time when the submarine menace was the gravest, the Government devised the plan of stringing wires across the fields and causing them constantly to disseminate an electric current.

"Undoubtedly more electricity is lost in the air than is brought into contact with roots of the growing crops. The new sys- tem aims to eliminate this waste. By em- ploying it the electricity is diffused directly into the ground, where it is brought into contact with the metallic element covering the seeds. High frequency electricity al- ways seeks out the points of lowest re- sistance. These are my metal coated seeds.

"Electrodes are set at the opposite ends of the field or garden plot and electrically charged. They serve to spray electricity thru the ground devoted to the growing of the crop to be so treated. In order that the juice may reach its proper objective the

seeds or shoots are surrounded with a metallic element. With ordinary seeds this can be done in large quantities and in a very few minutes. Indeed, the process is so simple that a farmer's lad operating it can coat enough seed corn in ten minutes for planting twenty acres of corn.

"The control of the electricity is brought about by metallically coating the seed with a finely divided non-deteriorating metal be- fore planting, thus creating lines of low re- sistance, since high frequency waves are automatically drawn to anything metallic. (See detail drawings in illustration here- with.)

"After the germination of the seed — which is both hastened and assured by the electrical treatment — this metallic element continues to inhere in the roots of the plant and absorb more current, thus establishing a continuity of the system."

The idea of metallically coating the seed does not debar its use for such garden pro- ducts as are grown from sprouts or from portions of the parent plant, as is the case with potatoes, celery, etc. McCreery de- clares that the electrical treatment will be wonderfully effective in growing garden truck.

"Where the ejectric system is used," he explains, "it is necessary that the individual plants have the metallic element previously alluded to. But this need not be a part of the seed itself. In fact, for certain plants it is just as well that the ground immediate- ly around them be impregnated with the metallic property. (See illustrations.)

"In the growing of asparagus or celery it is only necessary that the hills contain some of the mineral. In any event, the metallic coating does not exclude the ab- sorption of moisture or in any way inter- fere with normal growth processes save in the direction of hastening and strengthen- ing them."

Only a bed of minerals beneath the garden would defeat the projected action of the electric current, says McCreery. A bed of iron ore lying within a few feet of the surface would undoubtedly deflect the elec- tricity. This contingency, however, is a negligible one, save in a few regions where the soil is strongly impregnated with min- erals.

The efficiency of the treatment, it seems, is better known in relation to its results than in the actual details of its workings. (Continued on page 66)

Copyright by E. P. Co.

so

ELECTRICAL EXPERIMENTER

May, 1918

The Electro-Magnet in the Operating Room

By S. GERNSBACK

IN a modern war hospital, the electro- magnet is playing a big role nowadays. It is practically impossible to thoroly clean wounds of shrapnel splinters without the use of this practical apparatus, as in

tion of the needle, the surgeons at the be- ginning of the operation could not find the object and finally called for an electro-mag- net.

After applying the current, the magnet

The Electro- Magnet Has Proven Its Ef- ficacy in Many Surgeons' Cases. In This Instance It Found and Removed a Pho- noqraph Needle in a Boy's Knee.

v.-

many cases these particles are included by the dozens in the human body and it would be a great loss of time to the surgeon as well as pain to the patient, if each fragment had to be located and extracted separately.

When the wounded soldier is brought to a base hospital, all the big iron fragments are easily located, and are removed by hand and forceps. After this first operation a thoro research for small splinters is made, with the aid of a strong electro-magnet.

But that the electro-magnet should be in every hospital, ready to be used at any moment, is shown by the accompanying il- lustrations.

Some time ago a young boy was brought to a hospital in New York City on account of a swelling of the knee and excruciating pains in the same.

An X-ray examination showed that the patient had a phonograph needle imbedded deeply in his knee.

The needle must have worked itself into the patient's knee, a boy three years of age, while creeping on the floor. It was decided to remove the needle by an operation.

Altho there was a front and side view X-ray taken, to ascertain the exact loca-

was brought in the incision made by the surgeons in the patient's knee and the phono- graph needle was extracted at once and clung to the pole piece of the magnet.

DENTISTS TEST NERVES NOW BY ELECTRICITY.

It frequently happens that the nerve of a tooth dies, even when the tooth is apparently sound, without giving any ex- ternal indication. This almost universally results in an ab- cess in the bone structure at the end of the root of the tooth, which abscess may not give any local pain or external indication of its presence and may exist unknown for years. During this time the pus con- tinuously formed in the abscess is absorbed into the system and may cause various ailments, such as rheumatism, heart dis- ease, kidney disease, etc., all really due to the pus carried

by this dead tooth nerve but often attribut- able to other causes. The dentist may have examined the tooth many times dur- ing this period and found nothing wrong, because of the absence of any external signs.

It is the object of the invention here illustrated to provide an electric nerve-test- ing instrument, by which the dentist may determine absolutely whether or not the nerve of a tooth is vital. It was invented and patented by Mr. Arthur R. Darling, of Indianapolis, Ind. The instrument is pro- vided with a probe of conducting material of suitable form to engage the tooth, and this probe has associated with it an induc- tion coil with a variable-reluctance mag- netic circuit, interconnecting the primary and secondary coils. When the dentist presses on the center rod as shown, the induction coil core is pushed in and the reluctance reduced, thereby increasing the voltage of the secondary winding of the induction coil. The secondary of this in- duction coil has one terminal connected to the probe and the other provided with any suitable connection whereby the secondary circuit thru the tooth may be completed, as thru the dentist's hand, which is placed in contact with the patient's face or neck. Preferably the make and break device for this induction coil is separate from the in- strument, to avoid vibration in the instru- ment.

In testing the teeth the dentist grasps the instrument in the manner shown, push- ing down slowly on the center core plunger which raises the secondary voltage, and hence the strength of current applied to the tooth and nerve. If the nerve is dead, the dentist can push the central core rod entirely into the spool and the patient will feel nothing in the tooth being tested. If the nerve is vital, the patient feels the current in the tooth before the rod has been pushed in very far. A whole set of teeth may be tested in a few minutes.

COST OF ELECTRIC PIG IRON.

Based on experiments at Trolhattan, 4 tons of pig iron should be produced per kilowatt-year in a plant using only one fur- nace, measuring the energy at the furnace, says The Electrician. Figured on the amount of energy purchased, the output should be about 3.32 tons per kilowatt-year. Better results may be expected from a plant of two, or three or four furnaces. With a plant of four furnaces, it is assumed that an efficiency of 92 per cent can be at- tained, and with two or three furnaces be- tween 83 and 92 per cent respectively.

A New Electric "Nerve Tester" for Dentists Recently Patented. The Current Thru the Nerve Can Be In- creased as Desired. Dead Nerves Give no Response.

May, 1918

ELECTRICAL EXPERIMENTER

1 I

ENGLISH USE MICROPHONE TO FIND U-BOATS.

Two of the methods by which the British are effectively fighting the German sub- marine are by the use of new microphone detectors and explosive bombs of enormous power, according to a writer in the Tid- ningen, an authority on technical informa- tion.

English experts have so improved the use of the microphone on anti-submarine vessels, says the writer, that they are able to steer accurately and automatically down on the submarine, while formerly they were unable to locate a vessel beneath the sur- face. The microphones are placed below the water close to the keel of the vessel, and answer the same purpose as the micro- phone of a telephone. By listening to the beat of the submarine's propeller they can determine the exact location of the enemy and attack him before he has the slightest idea of what is happening.

The detection instruments used with the microphones are very complex. One of them shows the distance of the submarine on a graduated scale, the indicator respond- ing electrically to the sound from the sub- marine's propellers. The variations of dis- tance are shown with marvelous accuracy. Another device shows whether the enemy is on the port or starboard side. The' electro- magnetic needle moves to the side on which the sound is loudest and the ship is guided accordingly.

When the proper spot is reached bombs are dropt in the same manner as from airplanes. Their under-water force is so great that they can destroy a submarine ISO feet from the point of explosion.

Zip! Goes the Motor and Plaster Cast is Off

ELECTRICITY AS A TRENCH DIGGER.

It is reported that the French are making extensive use of electricity at the front in the operation of all kinds of excavating machines. Working in ordinary earth, four men with two wheelbarrows and a machine driven by an electric motor can shift from twenty-five to thirty-five tons a day. In a month a shelter with sleeping accommoda- tion for 500 men can be dug by a single company.

The doctors and nurses are right on the job in the present stirring times, when it comes to having electrical de- vices and refinements. If you think the soldiers and sailors have a mortgage on the "juice" operated inventions with which to push the "Hun" back across the border — well, guess again.

Ever see the "Doc" cut a plaster-of-Paris cast loose from a wounded patient? Yes, it was an awkward job at best. But now the electric cast cut- ter severs the encasement in one clip. It is provided with a special saw over a plate which slips under the cast as shown.

The Medical Corps is doing everything in human power to comfort our injured boys at the front thru the instrumen- tality of new surgical instru- ments.

When it is required to repair a part of a broken skull the new motor-driven drilling de- vice here illustrated will bore a hole with accurate precision, so it will not affect the tissues in the head. Such operations are often necessary at the front line and base hospitals, as, for instance, when a soldier has received a heavy blow on the head. This often results in a clot of blood forming which presses on the brain, depriving the victim of a part of his faculties at least. In such cases the surgeons must tre- phine the skull; i. e., cut out a triangular piece of the skull in order to remove the blood clot. Afterwards a silver plate is placed over the opening.

laying a regular network of interconnected lines, so that in the event of several being

Ever See a Electric Dri

A New Electric Appliance for Our Army Surg Rapid Plaster Cast Cutter. A Motor- Driven the Trick.

TELEPHONE CONNECTIONS ON THE EASTERN FRONT.

An interesting development in methods of electrical com- munication between head- quarters and the men in the trenches — namely, the use of wireless to a degree unex- pected previous to the war is commented upon in the French journal L'Industries Electrique. It was formerly assumed that wireless meth- ods of communication would be unsuitable in such circum- stances, owing to the ease with which messages can be intercepted by the enemy. The tendency has therefore been to rely mainly on tele- phone connection, notwith- standing the ease with which this connection may be rup- tured by bombardment. The destructive effect of modern artillery has made the ordi- nary method of laying wires along the surface of the ground or attaching them to trees of limited utility. Even buried wires are apt to be destroyed at an inconvenient moment by explosive shells, and therefore the depth at which such wires are buried has become continuously greater and the methods of protection more elaborate.

The Germans have sought to get over this difficulty by

Patient's Head "Trephined"? Here's a New II for Repairing All Kinds of Skull Fractures and Similar Head Troubles.

damaged there is still a path for the current. Even this precaution, however, may fail in a modern bombardment, and the Germans now appear to be relying to a much greater extent on wireless communication. The article in question quotes particulars which are said to apply to the latest German prac- tise, according to which it would appear that the antenna are mounted 4 meters above the surface, are about 100 meters long and emit waves of 300 to 600 meters. On the Eastern front about 110 wireless detach- ments are said to be employed.

eons Is This Blade Does

HIGH FREQUENCY CURRENTS HELP BRAIN TROUBLE.

The case of a model young woman who suffered from a mental aberration is de- scribed by Dr. S. St. John Wright in the American Journal of Electrotherapeutics. Some months ago she underwent a mental change, becoming morose, listless, apathetic and strange. On October 4th she declared life not worth living and would kill herself. She struck her devoted mother on the face, and acted riotously. During a lull in the excitement, they came to me, says the doc- tor. A severe proctatitis was found and treated by glass vacuum electrodes and the high frequency current and resorcin swab. Another slight riot occurred in the after- noon of the same day but none since. After five treatments her muddy countenance rap- idly cleared. She is now herself : active, cheerful and delighted, and delighting her mother and step-father. She has resumed her music, correspondence, and domestic activities. All evidence of tenderness and pain had vanished after the second treat- ment. This case well illustrates the fact that mental aberrations may be due to local focal causes, and that its removal or correc- tion at an early date restores mental equilibrium, and cheats the asylum.

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ELECTRICAL EXPERIMENTER

»

May, 1918

No. 1.

Television and the Telephot

By H. GERNSBACK

THERE are certain inventions which, altho not as yet existent, we may take for granted will be invented some day without any doubt what- soever. While the layman may not believe in the science of prediction, still there are quite a few things in physics that can be prophesied ahead of time quite safely. There are many inventions which have been predicted in the past and which are quite certain to be realized in the not too distant future. That they have not already appeared is by no means the fault of science, speaking generally, but simply because certain minor phases in the vari- ous endeavors have not as yet advanced sufficiently to make such inventions pos- sible. A point in case:

Jules Verne, almost fifty years ago, pre- dicted the submarine down to the last bolt. His prediction, of course, was laughed at and called impossible. At that time it was impossible, for the simple reason that the technique had not advanced sufficiently to make such a boat possible. Furthermore, Jules Verne had quite a clear conception how the ultimate submarine would be con- structed, and he so described it in his marvelous book, "20,000 Leagues Under the Sea." Of course, in those days the internal combustion engine had as yet not been in- vented, which was one of the chief draw- backs and which is the reason that at that time the submarine was not feasible. Neither had the storage battery been in- vented, and Jule Verne's idea of propelling a sub-sea boat by means of primary batteries alone, while feasible on paper, was not practical.

Another case in point is that of the planet Neptune, which had never been dreamt of until Le Verrier, the famous French mathe- matician, in 1846, by mathe- matical deductions, not only predicted that there must be another planet beyond Uranus, but he also pre- dicted— on paper — just where in the heavens the planet might be found. His prediction proved correct, and the planet Neptune was indeed found almost exactly in the region where Le Ver- rier had deducted that it must gravitate. This was one of the most astounding scientific predictions ever made, but this instance, of course, was founded upon the exact science of mathe- matics.

Another case in point is that we know to-day that our list of elements is not quite complete. There are several gaps as yet of cer- tain elements which have never been seen by man. Not only do we know that there must exist such ele- ments, but we also know the physical properties of them, should they be dis- covered some day, which no doubt they will. When we therefore make the assertion that certain inventions are coming, we make it on a safe, scientific ground, because such discoveries surely will be made without doubt.

The subject of the present article "Tele- vision, or Seeing at a Distance," is one of these inventions. Numerous inventors have busied themselves trying to invent an apparatus or machine whereby it would be possible for one person to see another while talking on the telephone, but so far noth- ing practical has resulted. The future in- strument on which the name "Telephot" (from the Greek tele-is.r, photos-light) has been settled, is supposedly an apparatus attachable to our present telephone system, so that when we speak to our distant friend, we may see his likeness not only as an immovable picture, but we will see his image exactly as we see our own image when looking into a mirror. In other words, the apparatus must faithfully fol- low every movement of our distant friend whether he is only five blocks away or one thousand miles. That such an inven- tion is urgently required is needless to say. Everybody would wish to have such an in- strument, and it is safe to say that such a device would revolutionize our present mode of living, just as much as the tele- phone revolutionized our former standard of living.

Most inventors who had been working in the past on this problem, failed to bear in mind a very important consideration.

If the Telephot is ever to be a success, it must of course be possible to attach it to the present-day telephone lines. That means that the instrument must of neces- sity work in conjunction with the telephone

What the Future Telephot Will Look Like in Order to be Practical. Light R Throws Light on Speaker's Face and is Reflected Into Lens L. Instead of a Mouthpiece, the Holes H of the Sensitive Transmitter Inside of Frame F Pick Up the Speech. The Picture of the Distant Person Appears on

Screen S.

without necessitating any more wires than there are used now. As everyone knows, the subscriber's telephone is connected with two wires to the central station. Each telephone instrument therefore requires two wires, or otherwise one metallic wire.

and the ground for a return "wire," which is the same thing as two wires. Over these two wires to-day, we do not only speak, but "Central" also rings your bell. In the case of a "pay-station" telephone, quite a few more functions are accomplished over these two same wires. It is also possible to-day to telegraph and telephone simul- taneously over two wires neither one or the other being affected. Why then should it not be possible to also send translated light impulses over these two wires at the same time that the voice impulses are trans- lated over them?

In most of the schemes offered by in- ventors heretofore, a plurality of wires was necessary ; in some cases several thou- sand pairs of wires. No matter how well such an instrument might work, this alone would doom it to certain failure. Another point is that the future Telephot must not be a cumbersome machine requiring motors and all kinds of other cumbersome ma- chinery, difficult to operate by the layman.

The future instrument must work the same as the telephone. In other words, all the subscriber has to do is to lift the re- ceiver off the hook, and he will immediate- ly see his friend just as if he were talking to him in the same room. All these re- quirements may seem hard on the inventor, but they are absolutely necessary as a sim- ple reflection will show.

The writer also ventures to say that no Telephot will ever amount to anything that necessitates the use of selenium. As is well known in nearly all past suggested television schemes, the selenium cell in one form or another was used. The underlying idea of these schemes is that light rays of the object striking the selenium cell varies the resistance of the same, and these various im- pulses are then sent over the line to be translated into a picture by various means and manners at the receiv- ing end. The trouble with the selenium cell is that it is not sensitive enough, and on account of its inertia does not work fast enough. Also in most of the pro- posed television schemes, a multitude of selenium cells is required, which again means a plurality of wires, thereby dooming the scheme at once. There must be something else besides se- lenium that can translate light impulses into electric impulses. Indeed, such a scheme is already existent, nature having worked it out millions of years ago. And while it is not electrical, it illustrates what we are driv- ing at.

The animal eye is the most marvelous television apparatus ever invented. Moreover, it is non-elec- trical. If we look at an object, the latter is thrown into our eye, which is nothing but a marvelously efficient camera, but instead of a photo- graphic plate, the impulses are thrown up on the Retina which records the object, not only in black and white as does the

May, 1918

ELECTRICAL EXPERIMENTER

13

photographic plate, but the picture is rec- orded in its natural colors on the retina. From here numerous fine nerve strings interlocked in the retina connect with the optical nerve, which nerve in turn con- nects with the occipital lobes of the brain, translating the various light impulses, {stimuli) with their component colors into a "picture," which is then "seen" in our mind. We say "seen" advisedly, because of course the picture is not actually seen in the mind, but the impulses which the

vibrations so faithfully that it is possible to recognize a friend's voice readily over the telephone as is done every day ; this is quite an amazing fact, if one stops to think of it. For in order to recognize a friend's voice, it is not only necessary to transmit the various sounds, but also all the overtones as well as the timber of the voice. Fifty years ago it would have been considered scientifically impossible if the proposition had been advanced that all this could be accomplisht by means of a

will be necessary to provide a lamp R at the top of the Telephot, which lamp throws its rays on the speaker's face; from here the light rays are thrown onto the lens, thence to be transmitted to the distant sta- tion. It naturally goes without saying that the ideal Telephot should transmit the picture in its natural colors, altho this may perhaps be asking a little too much of our inventors at first. Nevertheless, we think it will be accomplisht in time; the human eye does it, don't forget this.

The Dussaud Telephot Uses Two Perforated Discs B Revolving Synchronously. The Holes are Arranged Helically; thus Every Point of the Picture is Covered During One Revolution of the Disc. Selenium Cell C Transmits Impulses to Receiver T, which Vibrates Plate E. The Latter Only Passes Parallel Rays of Light. With this Machine It Is — Theoretically— Possible to Transmit Objects In Motion, Electrically.

retina has picked up are translated into another form, which we experience in turn as the sensation of seeing.*

As has been shown experimentally, the picture is retained on the retina for about one-tenth of a second. This is called the persistence of the image. It is this pheno- menon which is made use of in moving pictures, each successive picture staying on the screen for a tenth of a second be- fore the next one is flashed on. The fact that the pictures follow each other so rap- idly, gives tha impression on the retina that the objects are moving on the screen, which of course they do not.

Now, as we have shown that pictures can actually be transmitted at a distancef without the means of selenium cells, it is up to our inventors to devise something to do away with these cells entirely. It is safe to say that when the successful Tele- phot finally appears, it will be found to be a very simple apparatus, probably not much more complicated than the present- day telephone receiver.

When one considers how many different functions the diafram in a telephone re- ceiver performs, it seems that it should be a simple matter to translate light im- pulses into electrical impulses. Just stop and consider that a single telephone dia- fram can pick up several hundred pure notes as well as several thousand distinct kinds of noises, which in turn are trans- lated into electrical impulses. These im- pulses are then sent over the line only to be re-translated faithfully into the same notes and noises at the other end of the line, using nothing but a single diafram on another telephone receiver. Before the telephone was invented, it was thought that for each note, a diafram or vibrating reed was necessary. Strange to relate however, a single diafram records the human voice

* Light entering the eye, influences the light- sensitive "rods and cones" of the retina, in some manner as yet not understood. The changes are supposed to be photochemical in their nature.

t The picture is actually transmitted at a dis- tance. If the optical nerve is cut — the "wire" connecting the picture with the brain — we cannot "see" the picture, i. e., we will be blind.

single circular disc of iron 2^ inches in diameter and 1/64 of an inch thick. Never- theless, the telephone to-day bears witness that it is eminently possible.

So the question logically arises that if all this can be done, why cannot light im- pulses be translated into electrical impulses at one end, and be re-translated at the other into light impulses?

Bearing these various things in mind, we have tried to picture the Telephot as we imagine it will appear when finally in- vented. Our front cover as well as the illustration herewith shows the writer's idea. The future Telephot will be an in- strument attachable to our present tele- phone. The face of the distant speaker will probably be recorded on some sort of a fluorescent screen or plates, as we have here depicted. In order to show the picture to advantage, the frame F must be more or less deep, otherwise the sun or other light at the receiving end would interfere with the "received" picture. In other words, the picture would set back an inch or more as shown in our illustration.

The holes H belong to a highly sensitive transmitter (microphone), as it will be im- practical for reasons which will be apparent to use the present day mouthpiece. All that the person at the other end need do is simply to talk in a medium low-pitched voice. The sound vibrations will be picked up by the sensitive transmitter, and will be heard sufficiently clear in the telephone re- ceiver at the other station. In turn, the speaker's picture will be transmitted to his friend by means of the lens L, mounted in front of the Telephot. This lens is nothing but a photographic camera arrangement, and in the back of this "camera" P, the face or picture will be thrown just as a picture is formed on our eye's retina. Here the optical impulses are translated into electrical impulses which are now sent over the line along with the voice impulses.

In order that the distant person may see the speaker's face, it is of course neces- sary that the latter's face be illuminated. For it goes without saying that if the speaker was in the dark, his friend could not possibly see him on the other side be- cause no light impulses would be thrown on the "sending" lens. For this reason it

Quite a good many Telephots have been imagined and described as well as patented in the past. None of these, however, have ever appeared — most of them only exist- ing on paper. One of the first of these was invented by the Frenchman, d'Ardres, in 1877. There was another one invented by Sawyer in 1880, Next we have the Bid- well machine of 1881 ; the one of Weiller in 1889; as well as those of Szcepanich and that of Dussaud of 1898. None of these, however, were of practical value. We may also mention the comparatively modern Telephots of Rothschild of 1907; Belin apparatus of 1907; Kruh of 1910; Hoglund of 1912; A. C. and L. S. Ander- son of 1912; Stifle of 1915; the Rosing ap- paratus of 1915, and the Sinding-Larsen instrument of 1916. The more important ones among this host of Telephots will be described in this article.

One of the earliest Telephots imagined by the Frenchman, Dussaud in 1898, is illus- trated herewith.

This ingenious apparatus at the sending end has a camera A, at the rear of which is a metal disc B perforated with certain holes. The disc is driven by clockwork contained in the case E. The ingenious part of this arrangement is that the disc B is perforated in a curious manner, the holes being disposed in the form of a helix or involute spiral. In other words, when the disc rotates the perforations cut off suc- cessive points of the picture formed in the camera A. Thus at each fraction of a sec- ond, a ray of light is allowed to fall on the selenium cell C, and when the disc has made one full rotation, every point of the picture will have been uncovered, as will be clear by a little reflection. It is apparent that the selenium cell C will receive var- ious impulses due to the fact that more or less light reaches the cell. These impulses in turn are past thru a battery and a small transformer (induction coil) D, which is grounded at one end; the other wire goes to the receiving station. At the latter point, we receive more or less intense elec- trical impulses, and these impulses operate a very sensitive telephone receiver T, on which is hung an opaque plate E, having very fine transparent lines engraved on its face.

(Continued on page 51)

14

ELECTRICAL EXPERIMENTER

May, 1918

Electrically Heated Beds for the Wounded

ONCE it was thought that a patient was receiving the finest kind of treatment if he was surrounded by hot-water bottles, i. e., providing he required that kind of treat- ment. Now the English hospital experts have devised an electrically heated mat- tress for treating such cases as pneu- monia and shell shock. The hot water bot- tle provides an uneven heat at best — and for the proper treatment of such cases as these, the heating effect must be uniform and should be capable of fine regulation.

A successful solution has now been reached by Mr. H. J. Gauvain at the Treloar Cripples' Hospital, Alton, England, where two wards are now supplied with electric

The wires are connected with a switchboard on the wall at the head of a bed which contains a variable resistance, so that the current can be graduated to any required extent. It is so arranged that when the current is full on the temperature of the bed is raised 25° to 30° F. above that which would obtain apart from the heating, and this has been found in practise to meet the needs of the small cripples, many of whom are fastened on splints which do not allow of the close contact of the bedclothes. A fuse prevents the passage of any current exceeding this amount.

Several of the usual difficulties have thus been met : the temperature of the mattress can not rise to any dangerous degree, the

and infirmaries would save much time and relieve the nursing staff of a tiresome routine. Electrically heated beds have al- ready been found of advantage in the treat- ment of shell shock at field-hospitals, and for military purposes it will be seen that the current required may be instantly sup- plied from a portable dynamo driven by a motor-lorry or car, as shown in the accom- panying illustration.

GERMANS BUILDING ALUMINUM TRANSFORMERS.

Scarcity of copper has led to the con- struction of transformers with aluminum windings, says a German writer, and he contends that it is possible even in normal

NEW ELECTRICALLY HEATED MATTRESS

Copyngni by JB. P. Co.

A Recent English Invention for Treating Various Ailments, Such as Shell Shock, Pneumonia, Etc., Consists of an Electrically Heated Mat- tress Which Can Be Regulated as Desired. Where No Electric Currentls Available It Can Be Produced by Hooking Up a Dynamo to a Motor Lorry. The Mattress Is Water-Proof and Can Thus Be Sterilized in the Usual Way.

mattresses which have proved both safe and convenient in practise even when a child is the occupant of the bed.

The mattress does not differ in appear- ance from any other except that a flexible wire enters it at the head end thru a terminal which is flush with the surface, and therefore not exposed to injury. The resistance wire is insulated by glass beads in flexible metallic tubing incorporated in the substance of the mattress. The mattress is differentially heated and the heating ele- ment is so disposed that the maximum warmth is generated at the foot-end, less in the middle, and none at all at the head end. This distribution of heat is maintained in whatever position the mattress is turned, either from head to foot or side to side.

tubing is so flexible that the mattress can be shaken or rolled up, and the resistance wire is water-proof in the spiral metallic tubing, so that no short-circuiting results, even if the mattress is wetted. The mat- tress may be sterilized in the ordinary way. The system is equally applicable whether the bed be in or out of doors. The saving of time at the Cripples' Hospital amounts to an aggregate of three hours a day in each ward where the electric mattress has re- placed the filling or hot-water bottles, while inasmuch as the current required for maxi- mum heating is only half an ampere at 110 volts, the total expenditure of energy for 200 or more beds would be by no means prohibitive. It is believed that the general adoption of a similar appliance in hospitals

times to build air-cooled transformers cheaper and lighter if aluminum be em- ployed instead of copper. The ratio of the prices of insulated aluminum and copper wire is taken as 1.4:1.0. In the most eco- nomical design of transformer with copper windings it is necessary to leave consider- able spaces betwen the coils in order to obtain adequate cooling. When aluminum windings are used this space can be con- veniently reduced without prejudice to the temperature rise. Owing to the relatively greater proportion of the cross-section of the coils which is occupied by metal, the dif- ference between internal and external tem- peratures is less with aluminum windings than with copper. The difficulty of making joints in the winding is rather serious.

May, 1918

ELECTRICAL EXPERIMENTER

15

A New Phonographic "Loud Talker" for Public Places

By H. WINFIELD SECOR

POSSIBLY many readers have seen, or rather heard, loud-talking tele- phones in operation as the latter's sphere of usefulness is being ex- tended daily. They are being used very successfully for announcing trains in railroad terminals and have been used for several years now in announcing plays from the fronts of theaters in the larger cities, such as New York, and they have also found considerable adoption in railroad train despatching, as well as in a number of other fields.

The writer, while recently riding on a subway train, thought of the idea of com-

of cylinder type phonograph records mounted somewhat after the manner shown in the drawing, so that each respective record could be put into operation in re- sponse to each push button as becomes evident.

It will probably make the matter clearer to follow thru one stage of operation on such a loud-talker, provided with automatic speaking attachment in the form of a phonograph. Let us consider that this device was to be used on such trains as those operated thru the well-known Hudson River tunnels connecting New York City with New Jersey. The trains running be-

reason, and that is that these trains arc- gradually being supplied with women guards, and it was noticed by continual every-day traveling on them, and especially when the trains were crowded, that many of the women guards spoke in such a low voice that their announcements of the next station could not be heard beyond a few feet. With this arrangement, which is not only practical, but extremely feasible, the lady guard would simply push the properly labeled button on her key-board, the key- boards to be placed on the frame of the car door at which the guards are stationed, when the following operations would auto-

ttay or T Trains'

For Department Stores i

Copyright by E. P. Co.

Why not Make a Real Practical and Useful Application of the Phonograph by Combining it with the "Loud-Talking" Telephone as Illus- trated in the Accompanying Views? It Would Save Much Confusion and Misunderstanding in All Public Places, Such as In Subways,

Theaters and Stores.

bining these successful and practical loud- talking telephones with a phonograph at- tachment, which arrangement would seem to fill a great many requirements in public places, such as in subway and elevated trains, on steamships, in department stores, for store window sales, in theaters, et cetera.

A diagramatic layout, embodying the principal features of the phonographic loud-talker as here proposed and as it might be applied specifically for the purposes enumerated below, is shown herewith. Briefly considered, the phonograph attach- ment would consist of the proper number

tween the Hudson Terminal or Cortlandt Street, New York, make but four stops, and these are shown in the diagram, being respectively Cortlandt Street, Pennsylvania Railroad (Exchange Place), Erie Railroad and Hoboken. Each phonograph record would be made up with the proper number of repetition sentences for each respective . stop, as, for instance, the Cortlandt Street record might contain the record, "NEXT STOP CORTLANDT STREET — NEW YORK— ALL OUT," and this might be repeated several times with a brief interval between each sentence. This idea was conceived for one particular

matically take place : A small pilot light alongside of the push button deprest would light, showing that the apparatus was func- tioning properly ; a magnetic switch would close and remain closed, as the diagram shows, by virtue of a spring actuated trip ; this switch would close two distinct cir- cuits, one thru the proper magnetic clutch on the common motor drive shaft, thus putting into operation the "Cortlandt Street" record and its corresponding repro- ducer and attached microphone, while the second circuit, closed by the automatic mag- netic switch, would pass thru the micro- (Contlnucd on page 51)

16 May, 1918

"Vol. 6, No. 1"

By "ELECTRICAL EXPERIMENTER"— Herself

MY parens allwais say that nice peepel dont talc about themselvs and I gess their rite. But today Im 6 years old, so I kno you will excoos me for onct. i kno of coarse thet littel girls shoud be seen an not herd, but then i am such a lusti littel thing and so big for my age that i cant help being herd all over the United States an mutch mutch ferther then that, i am now herd every mons all over the sivilized

woarld from New seeland to Norwai, from india to shili, from Transvahl to Tchina and from Kanada to Djapahn. they all kno my vois and wellkom me evry mons. Thats pretti good for a six year old isnt it now? ! ? Besids i cant help being loud at Times for my parens put me in sech a loud new dres evry mons thet i think thei

sekretly doant mind it a bid if i am herd so much and thet so meny peepel talk about me every mons, an if it wasnt for my modesti I would tell you thet all the best girls and even old respektabel ladis all over the countri talk about me evry mons. For instans the literari Diges, the New York Woarld, the New York Tribuhn, the New York sun, the bostn transkribt, the phila- delfie inkwirer, the Chicago Tribuhn, the New York American, the Sinsinatti En-

kwirer, the Clevelant Plane deeler, the saint-luis Post despatch, an lotsanlots of other nice littel girls all over the countri print nise storis about me evry singel mons. an do you know that i am the Biggest elec- tricl young girl in the entier woarld now? Bigger then eny other 3 electricl girls kombined! i go now to over one-Hundred-

sou-sand peepel every mons ! 100,000 good an stantch f rends ! And no make belief frends either, no sirri, my frends pai for me to kom to ther Houses — evry one of them, honest. An moni toalks dosnt it now? Do you wondr thet i am prout an a bid stuk up?

Of coarse i wasnt allwais so big. Wen i was first borned I wend onli to 3000 peepls' Houses evry mons but then my parens got a new addishun to the fambly one day and his naim was advertisn Manger. An he lookt at me an took me in his hands and put up his nos and sneerd. An then he sais, sais he, feeling my puis, why the poor thing has no sirculashun, how can i ged ads for it? ! Thet maid me feel awfull sik but my parens padded me on the hed and sed,

0 thats eesy we will fiks thet soon.

So thei went an put nise brite dresses on me each mons, en then thei got the best peepel in the countri to fill me up with nise storis and artikls and rite-ups and then thei hiret the best artisds in town to paint an draw fine pikturs for me evry mons. An soon peepel was watchn for me all egsited evry mons to kom to their Houses. An wen i doant get their on time thei sent awfull kiks to my parens an sai I just got to kome or theil make it hot for em, thei like me thet mutch ! An if thet isnt apre- shiashun i honesly doant now what is, isnt it now?

An beleif me it keeps me bisi, evry mons

1 go to over 16,000 nouses thru the mails an 87,000 peepel tak me hoame from noos stands all over the countri, in Kanada in england an even in far away war torned Parees. An my noos stand Dyers kik aw- fulli too if i doant get there on time. An thei ball out the poor noos stands men as if it was their foalt when I run into train blokads and haf to wait weeks somtimes before the cars move on on akount of the war. I wisht to goodnes this war was over with, so I can get to my frends in time. I jest hate to be late an my parens the poor deers do their best to chais me out on time, even ahed of time but it doant help eny. An its getten woarser all the time. An it aint the woarst part that my frends kik. My parens kik much woarser. Their never satisfid with me. Thei allwais kik an fuss about me. I am never good enuf for em an thei allwais find more foalt.

My old man sais thet if it werent for the war I would be mutch biger an fatter then i am now. He sits up nites, sundais an holidais an skemes how to make me better looken an how to kram moar stuff into me. Sometims i think i bursd im so full of good stuff, but he doant think so. no sirri. las mons he spent over 400 dallers on me for artisds woark aloan, jest for the pik- tshers en then he had 3 kat fids when he sawr the bils. But he swaload hard an said, well i gess itl pai in the end. jest you wate till the war is over an i'll show em how to dress you up. youll be so fat and plum thet itl take your frends a week to lissen to all youll hav to tell em.

Well i gess the old man nows best but i wisht he wouldnt find so mutch foalt with me. we cant all be perf ekd, can we ! ? !

An lissen heres a good joak on him jest to show you thet he isnt perfekd ether, i hoap when se sees this he wont find so mutch foalt with me eny more.

Well in my februry dress on page 675 he went an printed a piktsher of a buldoag sigar liter, an then he went an rote a lot of doape an ses reel airi like, sip, gos the butten and pressdo your sigar is lited. jest

WOWWORIH BLDG.

E E MAGAZINES

EIFFEL TOWER

With This Issue the ELECTRICAL EXPERIMENTER Is Six Years Old. For Some Months Past the Circulation of the Magazine Has Been Over 100,000 Copies Monthly, Which Is MORE Than the COMBINED Circulation of the Next THREE Largest Elec- trical Periodicals. Not Bad for a Six-Year-Old I How High Would 100,000 Copies of the EXPERIMENTER Stack Up if all Were Placed on Top of Each Other? The Above Picture Tells the Story. Each Copy Is </s Inch Thick and 100,000 x '/8" Equals 1,041 Feet! Laid End to End the Magazines Would Reach 19 Miles, a Distance from New York to

Paterson, N. J.

May, 1918

ELECTRICAL EXPERIMENTER

U. S. Patrol Escapes Hun's Electrified Wires

like thet. An what do you think, the poor old fish never saw thet liter at all. The manufakterers jest sent him the piktsher an he wroate his own doape, thinking how smart he was an jest gessing all about it.

An pretti soon 100 and hundreds smoak- ing peepel began to rite him about thet dandy bulldoag sigar liter and wanted to now who made it so thei could bui one for their dens and their smoaking rooms an for their klub. jest look at the piktsher, isnt it a kiute littel sigar liter, o yes.

So dad went an sent all thoas 100 an hundreds of leters to thet Chicagoa Bull- doag sigar liter manufakterer bekaus he thot that maibe thei would give him a big ad for me. Yes like shuger thei did.

An what do you think thei went an rote dad? Thei thenkt him for all thoase nise leters but wanted to now if dad was batti in his skilite and what he ment by colling their poor dear good old bulldoag a sigar liter when poor fido was a ladis kurling iren heater, an not a sigar liter at all?!? My wasnt dad soar when he found out the bull hed maid of thet bulldoag?! the aire arount him was bloo for ours an ours an he triet to blame it on everi one in the plais. Poor old dad how could he hav gessed thet fido is hallo insides of him an thet their is a heating ellement inside the insides to heat mas or sis kurling iren in? ? ! But you cant beat dad. for you now what he went and did. youd never gess. well hes got the nerv to rite thoase Bulldoag peepel that with a littel change thei could kon- verd the kurling iren heater into a sigar liter eni way an sell em to all thoase peepel an thet thei should be thenkful to him for having gave them sech a good idee all for nothing? ! ! Can you bead it ! ? ? !

But i reeli shouldnt mak fun of dad for he gave me a lot of brant new hats for my 6t birthdai. He calls em headings an he spent a buntch of moni on em and I like em. Doant you think their reel peechi ! ? ! i do. The one he cals Orakel i think is the nisest an he said over 1000 years ago their

We Were Never so Humiliated In All Our Lives. Here We Went and Told You in Our February Issue that this most Honorable Dog was an Electric Cigar Lighter — but Alas and Alack it Ain't! But what is It? We are Ashamed to Tell You In Black Face Type. It's Too Glaring, so Please Read the Accom- panying Story, livd a ladi in a desert in a O-asis an her naim was miss Orakel an she told all the peeple what thei didn't now about an she was awfulli wise. An therefor now when my friends wan to now something or other i will tell them all about it thru my orakel thats pretty good for a six year old isnt it now ! ? ? !

Now thet Ive tole you all the latesd gos- sib i want to ask you a favor, a favor for me and one thet will help you lotsanlots 2.

Dad sais thet my frends doant read my ads enaf, and thet thei dont rite often enaf to my advertisrs. An he sais thet if thei only would and keep it up he could add 32 texd pages to me within 6 mo:is. Gosh i'd never beleif it but the advertisn mangr sais its so,' so it must be so after all.

You see dad spents all his moni on my texd dresses and blows in moare on them then he gets bak outo my ad pages, so at the end of the mons he ows hisself moni. An yesterdai the printr bios in with a new kontrakt an wants 20 persent moare to get me out evry mons. good nite, i thot dad would ether drop thru the floar into the seller or sale thru the seiling but he jest {Continued on page 50)

An American patrol, having past the first line of German entanglements and ap- proached the second line on a recent raid, was suddenly cut off by a current of elec- tricity sent along the wire line.

Instead of attempting an immediate re- turn to their trenches, which would have

meant certain death from electrocution or machine gun fire, the Americans clung close to the earth, and, later, when the electricity was cut off, returned in safety to their positions.

It was a thrilling experience for the patrol. The men set out from the American position in the hope of encountering the enemy at a point in the German trenches. They had succeeded in getting thru the first line and had crawled on until the second line was reached. When they were just about to start under the second line there was a bluish glow and, turning around, they saw long, livid sparks playing thru the barbed wire of the first line. The enemy had turned on a powerful electric current.

The patrollers quickly flattened out on the

ground, thinking they had been discovered and expecting to hear momentarily machine gun bullets singing overhead. Nothing of the kind happened, however. Apparently the Germans merely turned on the current by chance, hoping that if any Americans were within the entanglements they would

be killed on the wire or while trying to get out. The patrol returned safely to the American lines when the electricity was turned off. Usually a high tension alter- nating current is used to charge barbed wire entanglements ; a potential of several thousand volts is necessary.

An electric forge which requires but one man in its operation has been invented in England for use in munitions factories. Heretofore a forge has always required one man to hammer the iron and another to hold it on the anvil. Under the new system electricity does the hammering and the op- erator merely holds the iron and regulates the electric hammer.

A NEW DISCOVERY.

According to the New York Sunday World "Comic Section," Whenever You Want to Blow Up a House, Throw a Monkey Wrench Into a Dynamo! Simple, Isn't It? Hawkshaw, How- ever, Fails to Enlighten Us Just How the Dynamo Blows Up the House. Too Bad.

An American Night Patrol in France Recently Had a Narrow Escape From Electro- cution, When the Teutons Turned on Several Thousand Volts of Electricity thru Their Barbed Wire Entanglements in "No Man's Land."

18

ELECTRICAL EXPERIMENTER

May, 1918

"Sub"-Detector, Thriller In New

War

Play

DID you ever hiss the villain!! "Ask dad" he knows ! In the palmy days of the drama "pop" used to line up in the gallery and watch the villian steal the heroine, only to be foiled by the noble

by German spies who are in the guise of Belgian refugees. Then begins a series of dramatic incidents, thrills, heart-throbs and all thrown in, which lead to the capture and end of the plotters with U. S. Destroyers

It is interesting to note what novel ap- plications and innovations have been adapted to stage and screen during the past few years.

The accompanying photo is a scene from the play wherein Major Fielding and Colonel Sharrow are testing the practicabil- ity of the submarine detector. An electric cable has been laid to the water-front and a sensitive microphone placed in the water. The machine is supposed to show the pres- ence of a submarine and also its position from the microphone. The machine on its test indicates that a submarine is present which causes them great surprise. Later this proves true and the submarine 'is blown up.

The cast is noteworthy, and should be commended on the spirit shown thruout the play. So if by any chance "Seven Days Leave" should play your town or near your town — even if you have to walk twenty miles — by all means don't fail to see it ! ! — George Holmes.

RUSSIAN INVENTS ELECTRIC MA- CHINE TO BEHEAD 500 AT ONCE.

Shades of King Henry the VIII, what are we coming to. Modern science has come to the aid of the Bolsheviki, in case they decide to imitate the French revolution and intro- duce the guillotine, in the person of a Rus- sian engineer named Blubin. He has sub- mitted a new type of that instrument to the council of people's commissaries, and which is said to work by electricity; it will behead 500 victims with one stroke ! Next ! !

Electricity, Microphones, Spark Coils, True Military Atmosphere — All Abound in "Seven Days Leave," the Latest New York Dramatic Success. The Electric "Submarine Detector" Is Here Shown in Full Activity — Every Time a Submarine Is Located Its Exact Position Is Indicated by the Calibrated Magnetic Needle.

hero who always dropt in at the right moment ! Then too, we had the wily ad- venturess who always tried to lure our hero away from his woozy-woozy. Do you remember those days ! I'll guarantee not many of you do.

In these more advanced times it's the "movie" villain who holds our attention, and he usually wears a wrist watch ! ! Even then he can't hear you when you try and give him the razz ! ! Such being the sad and distressing circumstances, energetic pro- ducers have awakened to the crying need and presented the American public with a regular old-time drama, imported from England where it has played for more than a year.

Set to American ideas with none of the thrills left out, with a real American hero and heroine, villains, spies, adventuresses, henchmen and all the rest of the "fire- works" handed to you under the title of Seven Days Leave and you have a real, live, heart-throbbing, patriotic war play, that is bound to wake up that slumbering spark and send you looking for the nearest recruiting station.

The story surrounds itself with the ex- pected arrival of Major Fielding at Colonel Sharrow's house, Hampton Sandy, England. He has with him a special device which he has been working on, that will detect the presence of submarines. Incidently he is in love with Lady Mary Heather, a neigh- bor of the Sharrows.

He arrives with a model of his wonderful machine and also the working plans of the same. While there, the plans are stolen

in action and the final sinking of the sub- marine— with the lovers united again.

AVIATORS USE ELECTRICALLY HEATED CLOTHES.

The accompanying photo shows two mem- bers of the British Royal Flying Corps donning their electrically heated gloves and foot insoles, preparatory to starting on a cold night trip over the German lines. The current for heating the gloves being ob- tained from the storage battery or dynamo of the 'plane. In the aviation service of some of the allied forces electric heating for all the clothing has already been quite extensively adopted. The aviator will thus be enabled to attain higher altitudes with- out inconvenience from the extreme cold of the upper air currents.

Two Members of the British Royal Flying Electrically Heated Gloves and Foot Insoles,

Germa

Photo © by Underwood and I oderwood

Corps Are Here Seen In the Act of Donning Preparatory to Making a Night Trip Over the n Lines.

May, 1918

ELECTRICAL EXPERIMENTER

19

Research and Its Importance to Human Progress

By Dr. Willis R. Whitney

Research Engineer, General Electric Company

THE object of this paper is to empha- size the importance of material research and to lay stress on its necessity to any people who are ever to become a leading nation or a world power. I have called it material research because I wanted to exclude im- material research. I class under this head pure thought as distinct from thought mixed with matter. It is worth while making this distinction because it is not always recognized. It is very natural for us to feel we can think new things into being. Chemistry has advanced only in proportion to the handling of chemical substances by someone. When the study of our science was largely mental specula- tion, and the products and reagents largely immaterial, like fire and phlogiston, we ad- vanced but slowly. Ages of immaterial re- search for the philosopher's stone led only to disappointment. Successful results in modern times came from following Nature,

Scientific research, or research in the natural sciences and in the industries, might be defined as the pioneer work of the de- veloped country. In this light it is easy to see that our turn has come. Not long ago our pioneer work was of another kind. It was opening up the undeveloped land. It was actively and well done. But the work must change, because our require- ments have altered.

Two of the Research Laboratories Maintained by the Gen- eral Electric Com p a n y , and Dr. Wil- lis R. Whit- ney, Research Engineer of theCompany, Who Here Tells Us the I m p o rtance of Research to Human Progress.

more, or a rate below three a century. There has been so much industrial advance made within the past twenty to thirty years that fourteen new metals have been brought into commercial use within this period. This is almost as many in our quarter cen- tury as in the total preceding age of the world. Conditions are similar in all the applied sciences. The accumulated knowl- edge in any field is already very consider- able, and to get into the firing line of useful work one must go up past the baggage train of knowledge and experience.

I want you to realize that in America we are going ahead in the future at a rate dependent entirely upon our preparation. Laboratories are a relatively modern thing. In most of the sciences they are a develop- ment within the lives of men now living. I want you to see that we must be fore- most in systematic, organized research or we shall be distanced by other countries which already well recognize the value of

learning by asking and experimenting, rea- soning just enough from one stage of ac- quired knowledge to ask the next question of materials.

Man seems to be the supreme, mentally elastic organism. He develops by trying novelties and by taking new paths. No one knows to what extent he may develop, but everyone knows that thru acquisition of knowledge, or, let me say, production of it, he may transcend any physical limits. This will not come about by continuous repeti- tion of what we have already learned. Monkeys and parrots do as much. It will come thru the continual and active appreci- ation of new knowledge.

In the advance of civilization it is new knowledge which paves the way, and the pavement is eternal. While the physical structures of man are decaying, the facts he has learned are ever doing new service. Antitoxic devices will be increasing when locomotives are forgotten. Magnetic in- duction will work after the pyramids have blown away. We ought to see that every- thing distinguishing our lives from those of Indians has come from studying some- thing new.

I do not want you to look at research as an old, established utility. I want you to see it as I do : a powerful factor proved by the advance of the industrial welfare of the foremost countries, and a world- experiment of less than a century's trial, but something still unappreciated in Amer- ica. It is true that the earliest man and many of the lower animals accomplished ends by research, but I refer now to re- search in the natural sciences and to the research which in our day is necessary to our desired activities. These sciences are already very highly developed, and ad- vanced education is demanded by them. For example, if I wish to cure physical ills, I cannot expect to do it by reciting ancient incantations, nor by using roots and herbs, as was once customary. I must first fa- miliarize myself with an accumulation of previous experience. I must study anatomy, physiology, chemistry, bacteriology, etc. This is a relatively recent world-condition. Copper, iron and five other metals were known and used at the time of Christ. In the first 1,800 or 1,900 years of our era there were added to the list of metals in technical use (pure or alloyed) about eight

nezv knowledge.

When so much of our material welfare, the condition and extent of our manufac- tures, the quality of our agricultural ef- forts, and the health of our people, depend upon the rate of our acquirement of new knowledge, there ought to be much greater effort made along the lines of research than is at present the case. We call knowledge power, but we need to see that new knowl- edge is the second power of power.

I am in favor of anything which helps train the American student in the path of sanguine research. It can be done by re- search men themselves, but probably not by others. It is not the knowledge which the student preparing for research needs, so much as the spirit of the investigator. His thoughts should not be fettered by laws, but helped by them to fly. This can be done best by those who are optimistic al- most to the extinction of reason.

All service is based on knowledge, and knowledge is an ever augmenting thing which almost anyone may increase. If the stock is eternally useful, as it is, how great must be the value of the indestructi- (Continued on page 48.)

20

ELECTRICAL EXPERIMENTER

May, 1918

Modern American Electric Furnaces

By Frank C. Perkins

THE accompanying illustration shows the design and construction of a powerful industrial electric furnace developed at Chicago. The photo- graph shows a 5 ton, 3 phase electric furnace with two electrodes mounted in

Into the Yawning Mouth of This Gigantic Electric Steel Fur- nace May Be Loaded Five Tons of Steel Scrap — the Electric Current Is Turned On, Powerful Electric Arcs Sizzle, and Presto! — Out Pours a Stream of the Finest Grade Steel Ever Produced by Man.

a tilting roof which may be opened and closed for operation.

In the electric furnace the quality of steel produced is such that it cannot be excelled by any other process, and ordi- narily cannot be equalled. The electric furnace is virtually a crucible, with the heat of electric arcs on the inside — thus making it possible to melt and refine steel without the objectionable features of the blast. It leaves the metal freer from oxygen, nitrogen and other gases or slag inclusions.

As to the cost of the produce it is com- petitive with, or lower than, open hearth, converter, or crucible processes. This is in general due to the fact that steel foun- dries using electric furnaces make up their entire charge from old scrap, which in any market is enough lower than the combined scrap and pig used for the charge in other processes to offset the quarter of a cent per pound which electricity averages for conversion.

As the material is put directly into the furnace and its constituents are not oxi- dized unless oxidizing materials are put in for that purpose, the process is simple and the steel maker has the simple problem of having fewer elements to deal with and it is equally advantageous for steel or iron, and will prove as profitable for the small foundry as for the big steel plant. The rapidity of the process as compared with the open hearth practises, saves molding floor space and effects numerous economic

in the form of labor and other expense.

It is maintained that electric steel has greater density and is free from the blow- holes that entail so much machining loss when discovered too late, while its ten- sile strength is 10,000 lbs. per square inch greater than open hearth steel.

Electric steel has an elastic limit from 5 per cent to 15 per cent greater, and its working yield-point is 20 per cent to 50 per cent greater. This is large- ly due to the freedom of electric steel from oxygen, nitrogen, and slag impuri- t i e s which flame-heating processes leave in their produce because of the limitations of all fuel- melting processes, and which the electric furnace refines out of electric steel.

The fusing material in the electric furnace is at a higher temperature than the crucible, the heat is ap- plied inside the crucible while in fuel-melting fur- naces the heat is applied outside the crucible. Chem- ical composition of con- secutive heats can be held more closely to a standard than with any other proc- ess. This is the most no- ticeable when handling easily oxidizable metals, like vanadium, chromium, silicon and manganese. Alloy addi- tions may be n ade in the furnace itself rather than in the ladle, which increases the factors of thoro assimilation, diffusion and homogeneity.

When the five ton, three phase furnace has its roof tilted back it is in the charge position. This furnace is equipt with two top electrodes and one bottom connection to the bath. After the charge has been dropt into the furnace, the roof if pulled forward by a motor and sealed with a dry fire clay gasket. The spout is closed and the furnace is practically sealed, resulting in the most rapid de- oxidation of the steel. The electrodes are motor operated and an automatic regulator controls the motor operated electrodes.

TO THE U. S. SIGNAL CORPS.

You could get along wthout the infan-tree, If such a thing should really have to be; You could let up on "typewritin'," Quit most other styles o' fightin', And keep a battle goin' 'cross the sea; But I'll make an affidavy at my dear old

mother's knee There wouldn't be no battles in the trenches

'crost the sea ; Oh, there wouldn't be no chanst for them

to carry on the war, Without the kind assistance o' the U. S. Signal Corps. Charley Gordon, with a ukelele, sang this at Camp Upton recently. . . . The point may be adduced in vers libre; the signal corps is, after all, the nerve system of modern warfare. Take from the artil- leryman the news of what his shells and shrapnel are accomplishing out beyond in the unseen and his big guns are as good as silenced. Take from the infantryman means of quickly receiving and passing along orders — and he's a cooked goose.

ELECTRICITY TO DO ALL CHORES EVENTUALLY.

Thomas A. Edison has said : "The time is not far distant when practically all of the work now done by woman in her home- keeping, so painstakingly and laboriously, will be done better, more simply, without labor, by machine."

A noted scientist recently said : "When- ever you see a man, woman or child doing any form of manual labor, remember, that labor can either be reduced or entirely eliminated by the use of electricity; and that in nearly every case the comfort of the operator can be increased."

HOW NATIONALITY WAS CHANGED.

A fellow crazy with the heat propounded this. Two Ameri- cans fell out of an airship ; what nationality were they when they came down? We let the poor nut rave, and present- ly he gave us the answer. One came down a Russian, he said; the other landed on the tele- graph wires and came down a Pole.

American Type 5 Ton Single Phase Single Electrode Electric f urn ace with roof open

Sectional View of Five Ton Electric Arc Furnace With Motor-Operated Roof Tilted Back Ready for Charging. Even the Electrodes are Motor-Fed.

May, 1918

i JSRAftY

ELECTRICAL EXPERIMENTER

LICRARY i_. (M ■■■ i

Electii^oSJierar dizing " Pr eveitfts(icRust

21

TO assur£ protection against rust a sherardizing process is now standard practise for many electrical and me- chanical products where rust prevention is a vital necessity.

Marked improvements in methods of sherardizing have taken place since this practise was first adopted and have resulted in a uniform product with highly efficient protection to the devices so treated.

The process of sherardizing consists of baking the parts to be treated, with zinc dust of the correct chemical analysis, at a predetermined constant temperature, for a period of time depending upon the thick- ness of the protective coating desired. The zinc is deposited both into and onto the surface to be protected and by entering the pores of the metal becomes a part of the device itself. There is, therefore, no tendency to crack or scale off even when subjected to distortion or changes of tem- perature.

A feature of sherardizing is that when applied to threaded surfaces these are pro- tected as thoroly as the other parts and yet can be turned into place with absolute freedom. Neither does it weaken malle- able iron castings, since the temperature employed during the treating process is comparatively low.

As a result of the adoption of these meth- ods one of the largest electric companies has developed its own electric ovens for the process and its own testing plant, where pieces of the finished product are subjected to a test of 168 hours in a spray of salt water projected thru an atomizer by an air jet. This is a condition far more severe than would be encountered in service. Ex- perience proves that the ability to stand this test for a week forecasts indefinite re- sistance to atmospheric conditons.

The inordinate strength, the durability and the uniformity of the Electrically sher- ardized coating on steels is not generally understood. To explain these facts a microphotograph is shown in the smaller cut.

A piece of polished steel was electrically sherardized, cleaved to show the connec- tion between coating and steel then magni- fied and photographed. Note the even thick- ness of this coating, particularly at the corner. Electric sherardizing made this possible.

The black line between the coating and

the s±eel is the juncture of the two sub- stances. Small as it is shown, this junc- ture has. been magnified 150 times. The final weatherproof coating, if desired, can

The war has demonstrated two things : first, that warfare cannot be carried on without the necessary raw materials — that is, chem- ical, physical and metallurgical supplies :

Where the New Electrically Sherardized Articles Are Treated. This Coating Is Applicable to Threaded Objects As Well As Plain Ones, and Does Not Change the Character of the Mate- rial Treated. Due to the Low Temperature Used.

be given a polish equal to nickel plating.

The sherardizing equipment consists of an electrically heated revolving oven mounted on trunnions which are supported in pillow blocks. The oven is rotated by an electric motor geared to the driving shaft. Metallic resistance elements are placed on each side of the oven and cur- rent is applied to them thru collector rings. The best formulae for sherardizing can be carried out properly only in an electric oven where temperature, motion and atmospheric conditions can be perfectly regulated. — Photos G. E. Co.

Microphotograph of Electrically Sherardized Steel, Which Is Rust Resisting. The Black Line Indicates the Minute Joint Thickness Between the Metal and Coating — It Having Been Magnified 150 Times.

SCIENCE IN MODERN WARFARE.

The Great War has been called a "grand physical phenomenon" and a "battle of the sciences." To the layman this does not mean very much, but it is nevertheless a fact. It could just as well be called a "chemist's war" or an "engineer's war" or a "surgeon's war," so much have the vari- ous sciences contributed toward carrying on the war, says L. L. Edgar, in Edison Life. Most of us do not think of the part science has played in this great struggle. All we see and read of is the terrible fighting and wastage of human lives. It is very interest- ing to go into the subject deeper and see what has made possible all this fighting, and just where science and its application has to do with modern trench warfare.

Every known science has played an im- portant role, including chemistry, physics, hygiene, mathematics, engineering, geogra- phy, geology, metallurgy, geodesy, bacteri- ology, meteorology, astronomy, and many more of the physical and natural sciences.

and secondly, it cannot do without the or- ganization of the different scientific ele- ments in connection with the military estab- lishments.

Today one cannot tell whether the next officer he meets was a soldier before the war or a professor of science in some col- lege. Productive brains receive more care and protection now than any other part of the population.

Let us take some of the more important sciences and see what connection they have in waging war. The astronomer has be- come an important factor in preparing ar- tillery tables and maps and in perfecting instruments. The statistician is very valu- able in planning an offensive, as is also the meteorologist. When trenches are dug, the geologist is consulted, as he can tell the best places for shelter, and the probability of striking underground waters. The leader of the war in France, in the person of the minister of war, is a mathematician, and his personal staff are of the same profession.

The science of acoustics, about which, up to the beginning of the war, very little was known, has blossomed out into that of the greatest importance. The French have in use several systems of determining by acoustics the position of enemy batteries. It is possible by these systems to tell to within a few yards the position of a gun fifteen miles away, to determine its caliber, to tell the difference between the discharge, the flight thru the air, and the bursting. The spot from which a shell was fired has been found before the shell landed and ex- ploded. A battery of French thirteen-inch cannon, mounted on a railway truck, fired four shots at an invisible target over fifteen ( Continued on page 50 )

22

ELECTRICAL EXPERIMENTER

May, 1918

Electricity Makes the Hens Lay, by Heck!

Can electricity make hens lay more eggs? Yes, say the experts. While in New Lon- don. Conn., recently Professor Kirkpatrick and R. E. Jones, of the Connecticut Agri-

"Yes, sah," one said, ''an' a friend of mine who knows all about it says dis heah man Edison has done gone and invented a mag- netised bullet dat can't miss a German, kase

They Do Say That by Turning on the Elec Morning, That Chickens Lay Much Better.

Successfully Experime

cultural college, visited the poultry farm of Morton F. Plant, where electricity is being used successfully in increasing egg production. The success of this plan is owing to the fact that the hens eat more feed and a better balanced ration. Mr. Hoover's secretary please copy !

In describing the working of the experi- ment, Mr. R. E. Jones said there are 6.000 liens on the farm. 1,200 of which are in the experiment. These are divided into groups of 400 birds each. In the first the birds have electric lights and are fed from auto- matic hoppers, while the lights are on. The second group do not have lights, but are fed from hoppers, while the third are with- out lights and- fed by hand. The lights are controlled automatically by special electric clocks which it is only necessary to wind twice a week. The automatic hoppers used in the first pen are used only during the lighted hours. At 4:45 a. m. a two-candle- power light is turned on over the roosts, and at 5 o'clock three forty-candle-power lights are lighted in each house. These remain nil until daylight and are turned on again at dusk until 9 p. m., when they are replaced by the small lights until 9:15 o'clock.

The greatest increase in production is round in the case of the old hens, it is claimed.

trie Lights a While at Night and Also in the In One Instance 1.200 Chickens Have Been nted with in This Way.

ef dere's one in a hundred yards de bullet is drawn right smack against his steel hel- met. Yes, sah, an' he's done invented an- other one with a return attachment. When- ever dat bullet don't hit nothin' it comes right straight back to de American lines." "Dat's what I call invent- in'," exclaimed the other. "But, say, how about dem comin' back bullets? What do dey do to keep 'em from hittin' ouah men?"

"Well, mah frien' didn't tell me about it. but ef Mr. Edison made 'em you can bet youah life he's got 'em trained. You don't 'spose he'd let 'em kill any Amer- icans, do you? No, sah. He's got 'em fixt so's dey jes' ease back down aroun' BUTTONS de gunner's feet an' say : 'Dey's all dead in dat trench, boss. Send me to a live place where Ps got a chanct to do somethin'." — New York Herald.

MARCONI COMING OVER.

It is reported that William Marconi will replace Count Macchi di Cellere, Italian Ambassador at Washington. Count Cellere, it is understood, is returning to Rome and will likely be sent to Petrograd, where Italy- is now represented by a charge d'affaires.

Senator Marconi, according to these re- ports, will go to the United States as Italian high commissioner with the rank of Ambassador.

ELECTRIC "BONES" FOR THE MINSTREL.

Remember the last ministrel show you saw, when the "end men" rattled their "bones" so delightfully? Sure you do! Well the end men of the next minstrel performance you witness may spring a novel surprise on you, for a New York inventor, Mr. Samuel Sussman, has patented a new- kind of electric, fire-spitting "bones," which giVe promise of being a real novelty in the hands of a good minstrel.

The purpose of this invention is to pro- duce a dramatic lighting effect in addition to the rhythmic sounds produced by the per- former with the bones and synchronous with the movement of the same.

In the accompanying drawings are illus- trated the general arrangement of the in- vention. Two electric wires connect with two elongated parts made of bone or ebony or some such hard substance. Thru the- center of these, are holes drilled part of the way thru for the insertion of wires. At or near to one end of each of the bones and at one side of each, are attached metal spark electrodes. To each of these metal parts is attached one end of a wire.

A suitable portable box is provided in which are resistance coils and a connecting wire, which wire may be used for connec- tion with the electrical supply. There is also provided a bent frame or collar, com- posed of metal, which may be covered with rubber or other insulator, to be worn under the coat of the performer and at each end of this collar wires are attached connecting the same with the bones. This collar is also connected by wire with the transformer or resistance coils of the metal case .

In operation the bones are placed, in the usual manner between the fingers, and, the current of the electricity having been ap- plied, the movement of the operator in shak- ing the bones connects the metal parts, producing, by their contact flashing electric sparks. Needless to say the effect is best produced on a darkened stage.

ELECTRIC WIRES

is

EDISON-TRAINED BULLETS.

Two negroes were walking along the avenue discussing the wonderful inventions brought about by the war.

O r v i 1 1 e W right credited with having in- vented a new type of air- plane stabilizer. This stab- ilizer, operated electrically, uses a pendulum which swings in water.

MEWL

BOX CONTAINING

TRANSFORMER AND

RESISTANCE COIL S

Here's the Minstrel Up-to-Date. He uses Electric "Bones" Which Emit Flashes of Fire at Every Click.

May, 1918

ELECTRICAL EXPERIMENTER

23

Fixation of Nitrogen by Electricity

By Theodore Bodde, Research Engineer, General Electric Company

ONE often hears nowadays the ex- pression "fixation of nitrogen." All governments have been busy lately on this nitrogen problem, and it is evident that it tmist be one of great importance, especially just now in relation to the world war.

Several Foreign Countries, Including Ger- many, Employ the Birkeland - Eyde Electric Arc System for the Fixation of Nitrogen from the Air.

It seems appropriate therefore to explain to the public the reasons for and the mean- ing of the expression "fixation of nitrogen." First, just what is nitrogen? Nitrogen is a gas present in large quantities in the at- mosphere in which we live. In tact, four- fifths of the air which we breathe consists of the gas nitrogen, and only one-fifth part of it is the precious gas oxygen for which our lungs crave, and without which no life would be possible. This nitrogen of the air can also become precious and useful if we make out of it the powerful explosives used not only for breaking up rocks and mountains, but also for fighting the enemy in war time. Then, too, the innumerable plants in our fields and gardens could not live without nitrogen in their food. Our fertilizers are therefore made principally from that element.

Tho nitrogen is so abundant around us, when in the air it is like a bird in the bush. We can not catch it, for it is ex- tremely difficult to combine it with other elements into useful material. In fact, it is so recalcitrant to any chemical combination, that only very high temperatures or special

			f
M			N
s K	8 »! IS Fig. 3 EE.

The Shonherr Electric Process of Fixation of Nitrogen Employs an Arc Twenty Feet Long.

chemical conditions are able to overcome its independence and "fix" it to other elements. Once, however, that this nitrogen has been "lixt" or combined with another element it can be made easily into a liquid or solid substance, in which shape it can then be handled and transported and done with whatever we please. This is what we call "the fixation of nitrogen."

That June " E.E." m

B As we mentioned in the April is- g

B sue we are always pleased to hear g

H from our readers. The best eon- B

g structive letters making praetieal g

S suggestions for improving the "E. E." §§

g will be publisht in the " EDITOR' S H

g MAIL BAG." Write in now and B

g then, readers, and tell us what your g

B ideas are regarding the articles pub- =

g lisht in "your" journal — for your's it §g

U surely is. We don't publish it to suit H

■ OURSELVES— but to please YOU! g

g Therefore let us hear from YOU g

g once in a while. If you don't like an g

B article, say so. On the other hand. B

S you do YOURSELF and the Pub- §j

= Ushers an injustice by not telling g

g them which particular articles you g

g find interesting and instructive. Oh! B

B yes! we almost forgot — here's the g

B "advance 'dope" on that "June" num- g

g "A 100- Mile Electro - Magnetic m g Gun that Can Annihilate Cities." gj U "The Electrical Testing of Coal," 3 = by the U. S. Government. g B "A New Electric Recording Com- g = pass — It Solves Many Navigation Bj Problems." by Prof. Eugene Staege- g B man. g = "New Talking Motion Pictures." B B /'.V George Holmes. g g "The Dynatron — A Remarkable g = Xczv Vacuum Tube for Radio-Tcleg- g |§ raphy." g B "Television and the Telephot" — B = Part II — by H. Gernsback. g "How to Build an Electrically j Played Piano" — Part II — by Charles ' Horton. B g "Wave-Meters — Their Uses and B g Construction" — Part III — by Morton g g / / '. Sterns. Radio Engineer. B = "Experimental Mechanics" — Part B B I J' — />_v Samuel Cohen. B "Experimental Electric Furnaces." g = "Experimental Physics" — Lesson g m 13 — by John J. Furia. 'A. B., M. A. jj B "Burnt-out Lamp Contest." HI "The How and Why of Radio Ap- §j g paratus" — Lesson 9 — by H. Winfield g

This nitrogen which was at first so in- dependent has now become perfectly sub- dued and ready to combine with any cells of organic substances into powerful ex- plosives like dynamite or into useful fertil- izers.

One of the elements with which it can be forced to combine from its original in- dependent state and only under the coercion of an intense heat is the other element con- tained in the air, "oxven." Tims as ;;ir is a mixture of nitrogen and oxygen, we have only to subject it to an intense beat

and the chemical combination of these ele- ments takes place. The result is a gas which we call "nitric oxid." We can say that the intense beat causes the nitrogen to burn up into the oxygen and that the product of tliis burning process is the gas

Water:

The Electric Arc Used in the Fixation of Atmospheric Nitrogen by the Birkeland- Eyde Process Is Formed Between Water- Cooled Electrodes.

named "nitric oxid." This gas can be burnt still further, forming then a higher oxid of nitrogen and if then past thru water, it forms the well-known liquid "nitric acid," from which most of the other derivations of nitrogen are created.

This burning of nitrogen requires a tem- perature of about 3,(XX) degrees Centigrade, and the electric arc has been found almost the only practical means for obtaining this high temperature. 1 f air is made to pass thru an electric arc. the nitrogen combines with the oxygen and forms nitric oxid gas; but while cooling off, this nitric oxid gas dissociates again into its elements nitrogen and oxygen, and nothing is gained in the end. The reason for this is that this nitric oxid gas, tho stable at very high tempera- tures, becomes very unstable at the medium temperatures thru w hich it has to pass while cooling off. At the temperature of about 2,000 degrees Centigrade it dissociates read- ily into its elements. At a lower tempera- ture than 1,5(10 degrees Centigrade it be- comes, however, stable again.

Therefore if one wants to preserve the formed nitric oxid gas. it is of great ad- vantage and in fact absolutely necessary to cool it off very rapidly so that it remains during as short a time as possible in the un- stable state. Once that it is cooled off. (Continued on page 56)

This Shows a Section of the Pauling Nitro- gen Fixation Arc Chamber. The Arc Rises Between the Horns, Due to an Air Blast, Breaks, and Starts All Over Again in Rapid Succession.

24

ELECTRICAL EXPERIMENTER

May, 1918

NEW AUTO HEAD-LIGHT.

In this new auto lamp here illustrated, the manufacturers have designed an exception- ally powerful projector of compact dimen- sions, that is capable of projecting not only a projected main beam but also a non-glare general diffused illumination.

being slightly beyond the focal point of the main reflector. It also acts as a source of illumination in conjunction with the spheri- cal reflector. The result is a highly efficient projected beam augmented by non-glare diffused illumination.

The inventors have also found that the critical angle reflection for metal reflectors takes place at 52^2 degrees. That is when- ever a reflector is made to em- brace a light source beyond 105 degrees the resultant increase of light flux is a positive detri- ment to visibility at a distance.

A Clever Auto Headlight Which Throws a Powerful Con- centrated Center Beam of Light 500 Feet; the Outer Rays Are Non-Glaring.

As we analyze lamp devices, say its in- ventors, we find that as it appears to the eye there are two sources of glare, one the filament itself and the other the reflector surface. The inventors argue that coloring the light does not enhance the visibility with reduced glare when applied to a unit source. Neither do they believe in the possibility of prismatical deflection nor that a parabola can have an optically correct relation to a multitude of small prest lenses with a con- glomeration of axial alignments and focuses. Therefore the possibilities in glare reduction and still possessing light pro- jection are to minimize the glare due to direct visibility of the light source and to form a main reflector of least aberation and well concealed from the direct visibility.

In this new lamp an attempt has been made to carry out this idea with precision. The light source itself is embraced to the angle of 105 degrees with a spherical curve corrected for aberation and beyond the aperture of the main reflector we have an annulus or spherical curve whose geometri- cal focus is at an offset as shown in the illustration and therefore the light coming from the filament onto this annulus is not returned on itself but at a distance coin- ciding with that angle that the frontal screen intercepts. This frontal screen is translucent and light coming from the fila- ment will partly illuminate the same and light coming from the annulus impinges on

Arrangement of Translucent Frontal Screen and Parabolic Reflector to Realize a Strong Central Beam of Light, with Diffused Outer Rays.

the outer surface of the screen ; the screen then becomes highly illuminous and is then a source of diffused illumination as well as

WHEN "UNCLE SAM" TAPS THE WIN- DOW—YOU LOOK!

This window attraction de- vice is operated by an electric motor and it can be attached to any electric socket, therefore there is no necessity of disturb- ing your window display when starting or stopping the figure. Its life-like motion of rapping on the window, turning the head and pointing the finger toward the goods displayed, makes it one of the most attractive advertising novelties vet devised.

Rap! Rap! Rap! Goes Uncle Sam's Electric Fist Against the Show Window, and Next Thing You Know You are Buying a New Hat or Suit — or Perhaps a Bottle of Near-Beer.

"Uncle Sam's" clothing may be removed and either a "Santa Claus," "Policeman," or other suit substituted. The heads are interchangeable. It is thus possible to have three distinct characters making an entirely new attraction with each change. The figure stands 27 inches high.

ROME AND WASHINGTON EX- CHANGE WIRELESS "TALK."

Direct radio communication between an Italian Government station and the Arling- ton station of the United States Navy has been established and is being used daily for communications passing between the two governments and between their diplomatic representatives and foreign offices.

The daily statements of the Italian War Office will be received by radio from Rome and issued here for publication in the United States.

NEW ELECTRIC SHAVELIGHT FOR SOLDIERS.

It throws a flood of light — not in the eyes, not into the mirror or around the room, but on the face, right where you need it.

For the Boys in the Trenches or in Camp, There Is This New Electric Shavelight. It Carries Its Own Battery and the Lamp May Be Used Separately When Desired.

The soldier's days are busy. He must shave, usually at night. And it's not to be expected that his quarters — often an old barn, farm house, etc. — will be equipt with "all the modern conveniences." He will, therefore, find this new military style elec- tric light shaving outfit very serviceable.

The outfit consists of a high-grade safety razor, with six crucible steel blades ; the electric light attachment that attaches to razor handle; stropper; battery that will supply light for one-hundred shaves ; high quality aluminum trench mirror — all com- plete in a compact khaki case. The light attachment can be used on fountain pen or pencil for writing where light is dim or wanting — also for reading.

An electric apparatus has been devised for giving warning of impending air raids. It is claimed to be especially applicable to factories and public buildings. An electric resonator is placed on the roof, and on the sound of a given pitch being produced, the resonator causes a bell to ring in the build- ing until it is stopt. It is said that large areas can be simultaneously and instan- taneously warned.

A TOY CIRCUIT-BREAKER.

The accompanying illustration shows a toy circuit-breaker for protecting all types of toy transformers against injury from short-circuits. It opens the circuit automa- tically, and can be closed by push-button only when the cause of trouble is removed. It is low in cost and will be found of in- terest and service to the junior engineers

The Youngsters Who Operate Minia- ture Electric Trains and Motors Will Like This Little "Circuit- Breaker."

and electricians who operate miniature elec- tric railroads, motors and other various small electrical devices requiring some form of protective apparatus.

May, 1918

ELECTRICAL EXPERIMENTER

25

The Phenomena of Electrical Conduction in Gases

Part II. How Fast Ions Travel

By ROGERS D. RUSK, M. A.

IONS may sometimes travel at almost infinitely high speeds. The velocity of these little electrically charged parti- cles depend largely upon existing con- ditions, but may sometimes be as high as the velocity of light itself. This indi- cates that there is enormous energy back

Graphic Curve Showing How the Current of Electricity in a Gas Reaches a Maximum or "Saturation Value" at a Certain Potential.

of these particles, and if we experiment a little we may find this energy doing strange things.

For instance Franck and Hertz, two modern physicists, have recently discovered that when a gas is ionized, light may be produced when the ions become charged, Franck and Hertz worked mostly with mercury vapor, and when they raised the potential thru the vapor to 4.9 volts per centimeter, between the electrodes, they found the vapor gave off a certain amount of ultra-violet light. When they increased the potential to 12 volts they discovered that just at that point a great deal more light was given off. The first voltage evidently marks the point at which ionization begins and ions receive a single charge. The sec- ond voltage evidently is the potential re- quired to give the ions multiple charges, and in each case charging an ion causes the emission of light. This is quite in keeping with the electro-magnetic theory of light, and the modern belief in the electric theory of matter, for when the electric charge jumps to the ion the electro-magnetic dis- turbance in the ether is started. This kind of light may be called cold light, as an in- crease in the potential from 4.8 volts to 4.9 volts makes little change in the tempera- ture of the vapor, for at the former point no light is given off, while at the latter it is.

If some substance other than mercury could be found, giving a greater emission of light, the whole lighting industry might be revolutionized and instead of using in- candescent lamps, which waste the most of their energy in the form of heat, we might have lamps operating on low potentials and giving off little or no heat at all. The near- est approach to such a light today is the Moore vacuum tube light which works however at a very high potential.

The great variety of speeds which an ion may have depends a great deal on the fact that we may have the following four gen- eral classes of bodies in an ionized gas.

(1) single electrons.

(2) charged molecules.

(3) charged clusters of molecules.

(4) neutral or uncharged molecules. The latter may become charged at any

time by ionization thru the agency of heat, X-rays, radium, ultra-violet light, or col-

lision with each other. The existence of such ions may be proved by demonstrating the conductivity of the gas, and they may be removed from the gas by straining the gas thru a glass tube fitted with a plug of glass wool, or by bubbling it thru water. It will then be found to be unionised and nonconducting.

Straining the ions out makes it seem as if the ions must all be larger than the gas molecules which get thru, but this is not necessarily the case as it is most likely their electric charges which make them stick to the glass wool or remain in the water.

It may be well to notice, before going any farther, a very great difference between conduction of electricity in gases and con- duction in solids or liquids. The amount of current which may pass thru a conducting liquid or metal varies with the resistance E

as per Ohm's law, C = — . However this R

This Curve Shows How the Current in a Gas Behaves When the Potential Is Further In- creased Past the "Saturation Point."

is only partially true with respect to gases. The higher the voltage, the more the cur- rent falls below the value it should have by Ohm's law, until such a point is reached that an increase in the potential does not

Canal or Cathode or

pos. rays ~ Cathode neg. rays \

JL + Anode- — x

Pos. + Neg. roys

Fig- *

An Interesting Vacuum Tube Which Sepa- rates the Positive and Negative Ions in a Gas When Connected to a Source of Electric Current as Shown.

increase the current at all. At this point the current is called the saturation current. because all of the ions are being carried out of the field, as fast as they are formed. Hence this is a maximum value for the current. Its meaning can best be under- stood from the curve, Fig. 1, represent- ing the variation of the current with an increase in potential. The current as will be seen rises rapidly at first, but soon begins to slow down and at last reaches a steady value at A where the slope has become zero. The current then in a gas depends upon the total number of ions being formed in the gas. However, a very interesting phenom-

ena is noticed if the potential is raised a great deal higher still than its value for saturation. At a certain point the curve will begin to rise again showing that con- trary to expectations the current, after hav- ing seemingly reached a maximum, is now increasing again. The complete curve will now appear as in Fig. 2, where the second increase is found to occur from B-X on. This is due to the fact that when the po- tential is raised to a much higher value, the existing ions are swept across the field so fast that they encounter neutral mole- cules in their flight, and ionize them by collision, thus producing fresh ions, and thereby increasing the number of carriers for the current.

In measuring the velocity of the different kinds of ions the first necessary step is to separate the negatives from the positives. As the first measurements were made on ions in vacuum tubes, this can be easily accomplisht by such a tube as shown in Fig. 3. The rays between the cathode C and anode A, are a mixture of both positive and negative ions traveling in opposite di- rections. However, if each electrode is per- forated with a small hole near the center it will be found that some of the positive ions formed at the anode will travel thru the perforation in the cathode into the space be- yond it; while the same thing is true of the negative ions formed at the cathode, some of them will be projected thru the opening in the anode into the space beyond. So far, it has been found that the positives travel with a comparatively slow speed while the negatives may even travel as fast as 186,000 miles per second.

There is a certain class of modern scien- tists who believe this velocity is the highest possible velocity that anything may ever have. Those who believe this are the up- holders of the theory of Relativity. They hold that such realities as time and space cannot exist independently of each other, but are connected by a very close relation- ship (hence the name Relativity) . They say by this relation everything else in the uni- verse is conditioned, and that no velocity can exceed the velocity of light, which is the swiftest form of energy known travel- ing in the lightest medium, the ether. As this theory has met with a great deal of criticism it is probable that the question will remain open for some time as to whether a higher velocity is possible or not. How- ever, it is interesting to note that the veloc- ities of the ions do approach this value seemingly as a limit. Also this may tend to show that the fastest ions after all are nothing more material than light itself, altho we call them unit charges of elec- tricity.

(Continued on page 57)

Thomson's Famous Vacuum Tube for Meas- uring Velocities of Ions in a Gas.

26

ELECTRICAL EXPERIMENTER

May, 1918

Capt. E. H. Armstrong "Over There"

ALL American radio men are ac- quainted with Edwin H. Arm- strong, the young genius who ^ devised and patented the now well-known "Armstrong Circuit" for Audions, by which it became possible to make a single bulb regenerate or develop

Captain Edwin H. Armstrong. U. S. Signal Corps, With the American Overseas Forces in France. He is the Inventor of the Now Weil-Known and Widely Adopted "Armstrong Circuits" for Audion Receivers.

radio-frequency oscillations, so that un- damped, as well as damped, waves could be received and amplified.

We are pleased to reproduce a photo- graph of Mr. Edwin H. Armstrong, the well-known American wireless expert, who was awarded the medal of the Institute of Radio Engineers for his discoveries in the radio art. Such an award constitutes in itself a recognition of genuine service in the cause of radio science. Mr. Armstrong was born in the Lhiited States on Decem- ber 18. 1890, and after passing, with credit, thru the usual school curriculum graduated at Columbia University, from which he ob- tained his degree in 1913. Since that date he has concentrated his efforts on the ad- vancement of radio-telegraphic science, working in conjunction with Professor Pu- pin, the President of the Institute of Radio Engineers, in his important research work at the Columbia University laboratories. Mr. Armstrong is himself one of the Di- rectors of the Institute of Radio Engineers, besides occupying the post of President of the Radio Club of America.

Like so man)- other of his fellow citi- zens, he has answered the call of his coun- try to aid her in the role she has under- taken in the present struggle, and recently received his appointment as Captain in the

U. S. Signal Corps. This young scientist of twenty-eight has already won high dis- tinction by his work in wireless telegraph}'. Perhaps the invention most widely con- nected with his name is that of the 'Arm- strong Circuits," which have done so much to improve the sensitiveness to reception of wireless apparatus through the instru- mentality of the three-electrode valve. Mr. Armstrong has thrown much energy and zeal into the work of the Institute and has made many valuable contributions both to its discussions and its Journal.

Captain Armstrong is now in France with the American Expeditionary Forces. His skill in the radio art will prove of supreme value to the American army.

ment and squad of Radio operators — three to six of whom are supplied to each war vessel.

RADIO SAILORS GET INTO TRIM FOR SEA DUTY.

The accompanying photo is an unusual interior view of the new Austin Hall oper- ating rooms at the Harvard Radio School. Time and especially war will change all things. This room was formerly in more peaceful times, a part of the Law Library study at Harvard. Here the radio opera- tors which are to man Uncle Sam's rapidly- growing battle fleet are taught the science of wireless by experts, many of whom were well-known radio workers in civilian life prior to the declaration of war against the Central Powers. Now one hears the con- stant buz-buz of the radio-telegraphic dots and dashes all day long. The men are not kept at code practice all day long — but as fast as one class finishes its period, another takes its place. Thousands of future naval Radio operators are being taught how to handle wireless apparatus and how to send and receive the mysterious dot and dash messages at this school. Today a battle- ship, or any vessel of the line, would be practically "blind'' without its Radio equip-

UNIVERSITY OF ILLINOIS OFFERS WAR COURSES.

A war course in Radiotelegraphy is be- ing offered by the electrical engineering department of the University of Illinois to junior and senior students of this depart- ment as an elective. An oath of secrecy and appearance before a notary public by those entering the course, vowing that they will in no way divulge any facts learned in the course to any persons other than Government officials, is required. Ap- paratus for receiving messages (the re- ceiving sets alone being furnished), with confidential information and instructions for their use has been loaned the University by the LTnited States Signal Corps, Prof. Ellery B. Paine, head of the department of electrical engineering, is the instructor in the course.

The department of geology is also offer- ing an interesting course, dealing with the iron and coal factors in the warring nations of Europe, lines of communication and other topics concerning the geography and geology of the 'war theater. The Univer- sity has pledged itself to instruct 5,000 sol- diers, either engineers or regular soldiers, for skilled war service in the departments of mechanical and electrical engineering, including laboratory and shop practice. Announcement has also been made that the ground school of the work in military aeronautics will be doubled in size, pro- viding accommodations for 1,200 students.

Speaking about the capacity of con- densers, are you aware of the fact that the entire capacity of the earth is only .707 microfarads ?

'Code" Class of Uncle Sam's Naval Fighters at Austin Hall, Harvard Radio School, Where Thousands of Students Are Being Trained.

May, 1918

ELECTRICAL EXPERIMENTER

27

RADIO TAUGHT IN NEW YORK TRADE SCHOOL.

There is a great demand for radio men in the Signal Corps and to meet this need classes have been formed in many parts of the country. One of the most interesting in New York City is that held at the Stuy- vesant Evening Trade School. Only men who will be called in the second draft and who have been examined and placed in Class 1 A are eligible.

As these men are still earning their bread and butter, they can only do this work in the evening. Despite of this fact the re- sults are exremely good. The men arc heartily in earnest and eager to gain the required proficiency of sending and recciv- nig 20 words per minute. This is the stand- ard speed set by the Signal Corps. Thru the patriotic devotion of the instructors it has been found possible to have these even- ing classes free.

The equipment used in teaching the radio classes is of the best and very latest type. The head-bands are of the new single bar type widely used in the government sets and weigh less than any other style so far designed. The tone buzzer used is a new design giving the true 500 cycle spark pitch, so that the students are trained under as near working conditions as possible. This is more important than it might seem at first, for if the student is accustomed to hearing the signals on a low pitch tone he is very liable to be confused when he first hears a "real" wireless signal coming in on a high pitch note.

In an interview with Mr. T. H. Knox, principal of the school, as well as Jacob Weiss, Head Instructor, we were informed that the instruction is entirely free, all apparatus being furnished. All the drafted 'Class 1-A men are eligible, and all those that are subject to call. The school can still accommodate a few more men.

We see no reason why wireless amateurs should feel discouraged on account of the ■closing of their radio stations. To us, we see a' chance for the amateur to fix up his set to perfection, study up his theory, and when the war ends be ready to do efficient work.

Wireless communication was first estab- lished between Tapan and the United States, July 27, 1915.

NEWS OF BUENOS AIRES- NEW YORK RADIO. By Leon Girerd.

IMV1 pleased to inform the readers of the Electrical Experimenter of the progress of wireless telegraphy in this country.

In the first place, we have the ar- rival of the American engineer, Mr. Charles Edbridge, who comes to direct the work of installing an ultra-power- ful radio-telegraph station for direct communication between Buenos Aires and North America, the concession having been granted to a North Ameri- can company a year ago. This plant will be installed in San Isidro (near Buenos Aires), and the plans have already been approved by the govern- ment. Recently, however, some modi- fications have been suggested. The original plan called for the antenna to lie sustained by three towers 300 meters high (about 1,000 feet), but in the modification two have been supprest. The transmission system will be such as is used in nearly all of the large stations — Poulsen 500 kw., length of wave 24,000 meters. Altho there is no station in the city, it will have direct communication with the offices which will be established in the central boro. The price of this station is calculated to be $750,000 (American currency).

ft is also worth mentioning the at- tempts that have been made to com- municate with Nauen (45 km., from Berlin). The interested parties se- cured a three months' authorization to erect a station which they placed on "La Florida" farm in the Plomer sta- tion. The characteristics of this sta- tion were as follows : the most modern type of receiving apparatus was used, including a Lieben valve; the copper wire antenna was sustained by 16 posts, 32 meters (105 feet) in height, and a wave length of 3,000 meters; the ground consti- tuted a network of iron wires, 800 meters (about 2,600. ft.) long, interred in the form of a fan at a depth of 1 meter ; the antennae has the same reach toward the east as that of Nauen; taking into account the distance between Nauen and Buenos Aires, which is in a direct line, 13,000 kilometers, there are various difficulties.

Notwithstanding these difficulties, the

WOMAN OPERATOR IN THE U. S. COAST GUARD.

Yes, the women are bound to get t<> the front in this war. Mere we have Mrs.

M rs. Md.. ator

Photo © by Press Illustrating Service

A Busy Radio Class at the Stuyvesant Evening Trade School, New York City, Where Draft Registrants in Class A1 Are Eligible for Free Instruction.

Myrtle Hazard, Hailing from Baltimore, a Hale and Hearty Radio and Morse Oper- Now in Uncle Sam's Coast Guard Service.

Myrtle Hazard, who is from Baltimore and the only woman electrician in the United States Coast Guard. She is one of the few women radio operators in the government service. She learned the job in four months' study at a class in the Baltimore Y. M. C. A. and past the difficult govern- ment examination easily. She is both a Radio and a Morse operator. — Photo Harris and Ewing.

constructors have been able to get into direct contact with Nauen, but owing to the great atmospheric discharges (static), have not been able to decipher the messages; these discharges are due partly to the form of the antennae, which, because of their length and height, cut thru various atmos- pheric strata, producing violent discharges which disturb the reception.

Nauen has a power in the antennae of 200 kw. and a wave length of 12,600 meters. (Before rupture with the United States, it was supposed to be 300 kw. ).

At the end of the three months, the con- structors asked the government for an ex- tension of time of one month, stating that they had not been able to communicate owing to the fact that they did not know the exact time when Nauen transmitted with entire power. We note that this is not true. After several days delay, the Secre- tary of the Navy appointed an engineer to investigate and determine as to the prob- ability of their having received messages from Nauen. The report was unfavorable, and he ordered the dismantling of the station.

It is probable that they were able to re- ceive perfectly, since in 1914 the "Cape Tra- falgar" could communicate with Nauen from S. de Bahia, Brazil. At that time the (Continued on page 53)

28

ELECTRICAL EXPERIMENTER

May, 1918

External Grid Vacuum Valve Construction

A Unique and Simple Means of Making Experimental Amplifiers

By R. U. CLARK, 3rd

SINCE the introduction of the first real practical hot filament detector into the radio field, it has been the one great ambition of every wireless amateur to construct experimental vacuum valve detectors for personal use. Sad to relate but very few workers in the

in with the line of work being undertaken at the time of enlightenment, the incident will be forgotten or prove of little use. The author- — and probably many others — ■ had often thought of using the "High-low" type of electric light bulb for constructing valve detectors, but had always given the

A Home - made Experi- mental "Audion" at Last! It Is Easily Made With- out Any Glass - Blowing or Other Refined Tech- nique on the Part of the Amateur and Is Con- "tructed from a Standard Two Filament "High- Low" Auto Head Lamp One Filament Is Used as the "Plate," an External "Grid" Being Employed.

past have had the means necessary to per- form much research work in this branch of the art, owing chiefly to the expensive apparatus required for the actual construc- tion of the bulbs.

It is regrettable that the above should be the case — especially in view of the fact that the particular instrument under con- sideration may still be considered in the embryonic state, and quite capable of being vastly improved.

The present high cost of all good de- tectors of the valve-amplifier type pre- cludes the possibility of their being used, in furtherance of new ideas, except by those with money to spare, and in most cases places them beyond the reach of many earnest workers.

After a considerable expenditure of time and money, the writer has evolved a very simple and inexpensive method of making experimental vacuum valve detectors, of the external grid type, which will be explained at length in this article. It is the hope of the author that the idea involved, which has been thoroly proven, will be of great interest to a large class of readers. Cer- tainly no one field offers more opportunities of interest to experimenters than the one in mind.

Considerable incentive and encourage- ment may perhaps be found by others in the fact that, altho the direct outcome of no little work, the actual discovery of the double filament bulb, that plays the all- important part in making our experimental detectors, was the result of chance. During a few minutes' respite, spent in looking thru a motor magazine, the writer became aware that the solution of the problem of making valves was staring him in the face in the guise of an auto head-light bulb with tzvo filaments.

It often happens that such discoveries are the result of chance, but the fact re- mains that unless the particular finding fits

idea up as impractical. It remained for the urge of real necessity to demand that every possible means be given a thoro trial.'

As may have been already surmised, the real workable valves which are illustrated in the views accompanying this exposition, are not only of the external grid type, but also have two filaments, and thus giving double life to the instrument. It will be at once apparent that, since the bulbs con- tain two separate filaments and circuits within them, that one is to be heated by the low voltage battery, and the other is intended to constitute the plate, and when used as such its two wire leads will be short-circuited. When one filament has burned out in use it will be reconnected to form the plate, while the other filament, formerly acting as a plate, will furnish the heat necessary to throw out the stream of desirable electrons, on which the whole ac- tion of the device depends.

In the first illustration there is shown a view of the "High-low" auto head-light bulb which does the trick. This lamp should be purchased in accordance with the following specifications, and if not obtainable at any of the big auto supply houses in the read- er's home town, they can be had from the makers or others as listed elsewhere in this issue.* The bulb which the author, after many tests, has found best suited to the peculiar requirements of the valve detector is rated as follows:

Maker's

Number Volts CP.

T 14 6-8 4 &12, also 12 & 18 CP. semi- tubular in shape,

with double-contact bayonet base. Usual retail price 80c, with 35% off on lots of 5, making the price 55c each.

Unless these lamps are specially ordered

*Send stamped self-addrest envelope to the editor and names of concerns supplying these lamps will be sent gratis.

from the makers, and specified in this case "without bases," it will be necessary to carefully remove the brass ferrules and sealing compound, which together form the lamp base, after first cutting the connecting wires away at the contacts to which they are soldered. This work is best done with a small file and a pair of nail scissors, or pincers, and much caution should be ob- served to prevent accidental breakage.

It will be taken for granted that the experimenter intends to prepare more than one bulb for the initial try-out. Altho there may be a slight difference noticeable in the behavior of different lamps of the same make, the variation will be found in most cases to be very slight. The first bulb tried out, however, might be defective ; hence the advisability of using more than one lamp in testing out the idea involved.

A word at this point in regard to the operation of the valves under consideration may save much trouble later, on in the game. A good deal has been said against the hot filament detector which is mani- festly undeserved. It has been repeatedly stated that, unless exhausted of air to a very exact degree, devices of this nature will prove worthless as detectors. Quite naturally, this is true to a certain extent, but it is often possible to obtain almost equally good results from valves which may vary in this particular, provided the ope- rator is willing to work to find the opti- mum point of filament luminescence and high voltage adjustment, as required for the utmost sensitiveness under varying con- ditions of vacuum within the bulb at hand.

Another point worth mentioning is that of the strange and oftentimes erratic action of this class of detectors after they have seen considerable use, which calls for the same solution as above stated. The fact is that probably no one thoroly understands these bulbs as yet.

Before fitting up the lamps as detectors, the wires which lead to the inside should be tested for a possible short-circuit which must, of course, be avoided, except as ex- plained elseVhere. In order to gain a clear conception of the new bulb circuits, which are to be obtained by rearranging the fila- ment leads, the reader is asked to refer to the diagrams in Fig. 2. In this drawing the view A represents the original connections as made by the manufacturers. At the point 1 in this view the wires should be discon- nected. At B and C, same figure, the cor-

Diagram Showing How Two Filaments in the "High-Low" Auto Head Lamp Bulb are Con- nected to Give Two Different Forms of "Plate" Element.

rect wiring plan for using the upper and lower filaments respectively, at incan- descence, is shown.

{Continued on page 58)

May, 1918

ELECTRICAL EXPERIMENTER

29

INDEXING RADIO CALL BOOK.

Very little explanation is required. The illustration shows a method of ''tab" index- ing the "Oflicial List of Radio Stations of the United States" (or any other similar

A high duty Leyden Jar. — This shows how I made a transmitting condenser (or Leyden Jar) by clamping a jacket of sheet tin around the outside of a gallon bottle. The bottle is filled with salt water and a brass chain let down in it. The capacity is variable thru using a greater or lesser amount of water. Very good for a make-shift, as it took only about an hour to rig up four of them. Some light- gage tin, some 1^-inch stove bolts and some yi-'mch by ^4-inch pieces of wood, spring binding posts and chain and bottles constitute the necessary material, and they are easily obtainable.

Contributed by W. ROSS McKNIGHT.

This Professional Looking Leyden Jar Condenser, Suitable for Radio Transmit- ters, Is Made From a Good Grade Glass Jar Filled With Salt Water, and Having for Its Outer Electrode a Piece of Tin or Copper Firmly Clamped Around It.

book of reference) to make consultation quick and easy. These index "tabs" can be brought in any first class stationery store for 10c a box.

MINERALS FROM BROADWAY, NEW YORK.

"What you can't get in New York, you cannot get the world over," is one of the proverbs of New York. While many curi- ous things are found along Broadway, it will probably come as a surprise to many, that Broadway is one of the most curious mineral centers in the world. Very few people realize that on Manhattan Island over 118 varieties of minerals have been found — not only minerals, but real gems.

For instance, on Broadway and 157th Street, there have been found aquamarines weighing l*/2 karats. From this locality also come brown tourmaline, golden beryl and rock crystal, which can be cut into gem stones. Of particular interest to the elec- trical man is the fact that on Broadway and 176th Street there are found, besides beautiful green tourmaline gems, magnet- ite and iron ore, chalcopyrite, malachite and pyrrhotite, also a source of nickel in a crystal form, which is considered quite rare in any locality.

Many other rare minerals in addition to the few listed are zincite, used in the manu- facture of the perikon detector ; also the lead mineral roeblingite. Other minerals of interest found along Broadway are agate, amazon-stone, amber, amethyst, chrysoberyl, hre opal, garnet, peristerite, prehnite, rock crystal, rose quartz, smoky quartz, precious serpentine, tourmaline and willemite. The commercial minerals include silver, lead, zinc, copper, iron, feldspar, molybdenite — which is used in the molybdenite detector — grafite, asbes- tos, mica and beryl. The radio-active minerals autunite, torbernite and urani- nite are also noted. Also a very good grade of iron pyrite called commonly "fool's gold" has been found in fair quantities in the upper parts of Broad- way. Iron pyrite, as is well known, is an excellent mineral for detecting radio signals.

FREAK OF RADIO.

A peculiar phenomena which has never been explained well is that which takes place at several points along the Atlantic Coast. There are times when a vessel is in radio communication with another and the signals gradually die out and then increase to their normal sound. A similar effect has been noted by amateurs, who, when sending in one direction can cover much greater distances.

Zeppelins can attain a height of 18,- 000 feet, or about 3j4 miles. They easily remain in radio communication with their home stations.

To Index Your Radio Call Book or Catalog, Go to Your Stationer and Ask for a Box of "Thumb Index Tabs," Here's the Result.

MICROPHONE "HOWLER" FOR CODE PRACTISE."

Herewith a photo and wiring dia- gram of three handy pieces of "BUG" laboratory apparatus showing what can be done with odds and ends of a wire- less experimenter's assortment of in- struments which are now idle. It consists of a telegraph key made

on the prinicple of a VTBROPLEX, and it works, too, having tried it out on long telegraph lines of the A. T. & T. and Cen- tral Union Telegraph Co. A handy box for holding flash light batteries, so that connection may be made from each pair of cells, spring clips can be seen at the end of the box, for each pair of batteries, both ends have these spring clip connectors.

This Genius Has Built His Own "Hy-Tone" Microphone Howler for Practising the Code. By Varying the Distance Between the Microphone and Receiver the Note Produced Can be Changed as Desired.

The box now has a capacity for 24 cells but only 12 have been placed in it. This gives me a range of voltage from 3 to 30 at the present time.

Best of all is the contents of the small box, a telephone transmitter, telephone re- ceiver placed rigidly in an extension tele- phone bell box, and made into a "howler" in imitation of the Sayville, L. I., station wireless tone. It gives a remarkably clear, shrill tone of a frequency of 500 to 800 cycles, depending on the distance the re- ceiver is mounted from the transmitter, the transmitter being solidly mounted in grooves cut in the edge of the box and the receiver mounted on a screw, similar to the method used in adjusting the magnets of a telegraph relay.

Several "wireless bugs" have listened to the tone of this "howler" and pronounced it an excellent reproduction of the Sayville tone. A home-made induction coil made on one bobbin of a buzzer, and wound with a resistance ratio of 1 ohm to 50 ohms, is connected in series with the battery and transmitter-receiver and the receiver con- nections are taken from the secondary winding of the coil as shown in diagram. When telephone receivers are being used, the box is packed with cotton and a lid put on it so the sound of the "howler" will only be heard in the 'phones.

The ratio of the resistance of the wind- ings of this induction coil is not according to Hoyle. I found that I only had that much wire to put on it, but a pair of re- ceivers on the secondary winding gives the proper amount of tone to the receivers to make it sound as if its name-sake were

To frame

I. Coil

To corf on buff on

-Jllllllli

Key

Simple Form of Circuit Used With the "Microphone Howler." The Inherent In- stability of All Microphones Gives Rise to a Musical Note of 500 Cycle Pitch, Due to the Reaction Between the Microphone and Receiver.

really coming in. The "bug" key can be made from odds and ends which most every amateur has in his work shop and it surely beats sending with the old stvle key. Contributed by CECIL A. RICH.

30

ELECTRICAL EXPERIMENTER

May, 1918

The How and Why of Radio Apparatus

By H. WINFIELD SECOR, Assoc. I. R. E.

NO. 8— DETECTORS.

From time to time we will describe one particular instrument used in either the radio transmitting or receiving set, explain- ing just how it works, and why. We have received so many requests from new read- ers asking for such explanations that we have decided to publish this matter in serial form. In the course of several issues all of the principal transmitting and receiving apparatus will have been covered. The subject for the eighth paper is DE- TECTORS.

vacuum valve or Audion detector proves feasible. For trench and field work the mineral detector is pre-eminently ' the type to use ; it is at once rugged, simple in operation, always reliable, easily repaired, and last but not least, it requires no battery. An Audion detector is, on the other hand, liable to breakage, disarrangement of the electrodes, requires frequent adjustment, and must always have a fresh battery to light the filament, besides a 40 to 60 volt dry-cell battery for the wing circuit.

The minerals most in use as rectifiers of

Miners/ Det non-bat type

H Res. Tel.

— , EC. .oojmf *Jii

-1-

t \c

Moving ironioire band Steel magnets

iso Obm — 7 — t Phones

Mineral del

tt.Res. Tel

Potentiometer

-2-

Fleming Valve , Rheostats.

Tel Pec.

-s-

D C mil- amm

\ / tickler ■> ' coils *

is -so wits iMf* " W|

Mineral det

The Principal Types of Radio Detectors Are Here Illustrated and Described. The Detector Is One of the Most Important Apparatus Used in Receiving and Translating Wireless Messages and Should Be Very Carefully Studied.

In all modern radio receptors, especially in those sets used by the army and navy, the detector is one of the most important parts of the whole equipment. It has been developed and refined until at the present time it is quite a respectable instrument so far as its efficiency is concerned. The detectors now in use classify broadly into three groups, viz: mineral rectifiers (with- out battery) ; mineral rectifiers (with bat- tery), and vacuum valves. Each class of wave interceptor and translator seems to fulfill certain requirements best. Where the vacuum valve would prove too sensitive and delicate, as in mule pack sets, etc., the mineral type detector proves best. Where the radio set is subject to fair treatment the

the high frequency oscillation groups are the following : Steel point-carborundum, gold or steel point-silicon, gold or steel point-iron pyrites, metal or grafite point- galena, zincite-chalcopyrite, silicon-arsenic, silicon-antimony, and "cerusite." There are a host of others, of course, but these are the principal ones being used on army and navy sets to-day. Some of the minerals are best known under their trade names — as "Perikon," "Pyron," "Radiocite," etc.

As aforementioned, radio investigators have devised many different forms of de- tectors, most of which rectify the high fre- quency antenna currents, i. e., change them from alternating to direct or uni-directional impulses by some kind of valve action, thus

rendering them capable of operating the telephones at an audible frequency. This rectification process is shown graphically in Fig. 1 at A, B and C. Curve A shows sev- eral damped wave trains such as received on a radio antenna ; curve B delineates these wave trains rectified by the detector so that the current is allowed to pass only in one direction, while the graph C denotes the form of current pulse passing thru the telephones, where the rectified current is smoothed out by the inductance of the tele- phone receiver windings. Thus it is seen that what the operator hears in his head 'phones is not the high frequency aerial oscillations, but a rectified pulsatory current having a (group) frequency corresponding- to the frequency of the current charging the condensers at the transmitting station. If it employs a 500 cycle alternator, then the operator at the receiving station hears a 500-cycle note in his head 'phones, etc.

As to the hook-ups used with the mineral detector, let us glance at Fig. 1. This shows how a non-battery mineral, such as galena, iron pyrites or silicon, is connected up in a simple tuned circuit comprising aerial, tun- ing coil T C, and ground. A high resistance pair of 'phones is invariably used in such systems, connected either across the de- tector or the fixt condenser as the dotted lines indicate. Fig. 2 illustrates how the battery-using mineral is commonly hooked up with a potentiometer having several thousand ohms. A better form of circuit and now used in the Signal Corps outfits is shown at Fig. 3-A. Here the current passes around thru the secondary of the loose coupler. Three volts (2 dry cells) i? usually the potential applied across the ter- minals of the potentiometer. The potenti- ometer slider (or switch) is adjusted until the maximum strength of signal is heard in the 'phones. Also the direction of the current thru the mineral is important and it is well to provide a pole-changing switch in the battery circuit so that the current can be reversed thru the detector. The mineral is usually connected to the nega- tive battery line.

The Perikon Detector was developed by Dr. G. W. Pickard. This detector consists of two crystals — copper pyrites (Cu Fe Ss) and zincite (zinc oxid ZnO), held in firm contact against each other in the manner shown. The copper pyrite crystal is mounted in a cup mounted on a spring-actuated rod provided with a suitable knob, by which it can be swung in any direction. Zincite crystals are mounted in a large cup con- taining several pockets, the mounting of both of the minerals being effected with a low fusing solder, Wood's metal or Hugo- nium alloy. The action of the Perikon detector is supposed to be based on the rectifying principle previously described; that is, it will pass current in one direction but not in the other, and thus the incoming- radio frequency oscillating (alternating) currents in the aerial are rectified and caused to give a sound in the high resist- ance 'phones connected to the detector. This detector is invariably used with a bat- tery of about two cells and the potential applied regulated by a potentiometer. When using a battery the polarity of the current must be such that the positive wire is con- nected to the copper pyrite crystal.

Diagram Fig. 3 shows the simplified con- nections for a "Radioson" (sealed-point) electrolytic detector, the 'phones serving as

(Continued on page 64)

May, 1918

ELECTRICAL EXPERIMENTER

31

Design for a Panel Transmitting Set

Did you ever consider that compactness and efficiency in wireless means success? Many amateur wireless operators place their transmitting apparatus a good distance apart so that each instrument may show off to its best advantage, and by doing so they little consider the unnecessary length of the connecting leads, which offer great re- sistance and very often a lack of resonance in the circuit, thus producing unsatisfactory results.

For the benefit of those who are looking for success I shall endeavor to describe a Rotary Gap, panel type, transmitting set, which is not only very efficient but offers a good appearance. A set of this type makes possible very short connecting leads, which are absolutely necessary in an effi- cient short wave radio transmitter.

The arrangement of the apparatus should be clearly seen by the accompanying draw- ings. Compartment A contains the trans- former embedded in sealing compound, B is the adjustable condenser, consisting of twelve 8x10 inch glass plates, coated with tinfoil 6x8 inches; these are connected in sections of two plates each and controlled by switches C, mounted on the panel. Com- partment 1) contains a rotary gap of the

Jena/

B/acA f/ire

W \- «"— I I-

Ground

ftg.2

By James R. Hopkins

ring type; the ring and rotary arm should be made of Bakelite. E is a protective device to carry off kick-backs and may be of the carbon rod or of the condenser type, as the builder prefers.

Side and Rear Views of Panel Type Trans- mitter, Showing Arrangement of Oscillation Transformer, Rotary Spark Gap, Etc.

How the Front of Panel Type Radio Transmitter Looks. Rotary Gap at Top; Condenser Switches at Center; Kick-back Preventer at Bottom.

The oscillation transformer F is of the pancake type. A resistance coil G is placed in series with the rotary gap motor to vary its speed, and the light H may be connected in series with the transformer for short dis- tance work.

I am not able to give any fixt dimensions, as transformers, motors, etc., vary consid- erably in size; with the Yi K.W. set I am using, the cabinet is 12 inches long, 6 inches wide, and 18 inches high, built of Y2 inch birch, with the exception of the panel, which is of black fiber J'\ inch thick, this being

firmly screwed to the case to prevent warp- ing.

The hook-up is given in Fig. 1 and the general scheme of arrangement is shown in the side and back views in Fig. 2, while the front view (photo) shows the panel on which all control switches are neatly mounted.

If the general idea of construction is car- ried out, I am sure the builder will be greatly pleased with the results. I used this set with great success for over a year prior to the war.

A UNIVERSAL SOLDER.

A very novel scheme for making a solder that beats the ordinary solder is as follows : Mix with a good brand of soldering paste as much granulated bar or wire solder that possibly can be mixed (which is done for the sake of economy) and a solder of excel- lent qualities will be made. It is useful to the electrician in that wires "up in the ceil- ing" can be soldered by applying this mix- ture, and it is then only necessary to apply the heat of a match. Many other ways for its use will suggest themselves to the every- day practical man. In fact, it will save lots of solder from being wasted by drop- ping to the floor, as is the case when ap- plied by the old method.

Contributed by E. DUSKIS.

Imepro/ec/or

Complete Wiring Diagram for Panel Radio Transmitter. Note Pilot Lamp in Primary Circuit. Gap Motor Has Speed Controlling Rheostat.

TO STOP LIGHTS FLICKERING.

Many radio amateurs who are annoyed, and are annoying others, by drawing too much current from their supply line, might be interested in a way to remedy this. The diagram illustrates this without much de- scription ; a few words will not be amiss however.

!	!
To f rans.	i 6,66
r	3- 120 traff

cordon /amp

J CMo/tis

Balancing Radio or High Frequency Trans- former, With Lamps to Prevent Flickering of Lights on Regular Lighting Circuits.

This idea is not recommended for powers exceeding one half kilowatt as the cost of operation is higher. The writer uses this with entire satisfaction on a transformer of 360 waits input; to balance this current

consumption, a lamp bank consisting of three 120 watt carbon lamps is used. In the case where a transformer of higher or lower rating is used, the lamp-bank or any other resistance must be made exactly ac- cording. It is important to use nothing but silver contacts on back end of key lever, of the same size as those used on trans- former circuit; it is well also to have as little vertical play as possible.

Contributed by L. H. REINER.

DETECTING 'PHONES WOUND WITH GERMAN SILVER WIRE.

The use of high resistance 'phones for use in wireless telegraphy has led many un- scrupulous manufacturers to wind their 'phones with German-silver wire, getting the necessary resistance without the effi- ciency of the copper wire wound 'phones. This cannot be detected by measuring the resistance and since in many cases a few layers of copper wire are wound on over the German-silver, it is rather difficult to detect these inferior instruments.

However, we can take advantage of the fact that the coefficient of resistance of copper is much greater than that of Ger- man-silver. It is only necessary to connect a galvanometer in series with the 'phones and a few cells of dry battery. On closing

the circuit note carefully the reading; allow the current to flow for several minutes and if the galvanometer needle gradually drops back you may be sure the windings are of copper wire; but if the needle stays at the same point or nearly so for several minutes, the windings are of German-silver.

Contributed by T. W. BENTAMIK.

A CORD TIP TERMINAL.

ffq.l

f/ff.3

fry. 2

°/oce for cord

It's Always a Mean Job to Properly Connect Cord Tips to Apparatus. Here's a Good Way of Doing It.

Take a piece of springy metal, one inch long and 1/4 of an inch wide. Put a small nail in the middle and bend the strip of metal as shown, and bore a hole in each end to fit a screw. It will be the saving of much time and patience.

Contributed by L. SIMMONDS.

32 ELECTRICAL EXPERIMENTER May, 1918

Theory of Tuning, Wave Lengths and Harmonics

By Prof. F. E. AUSTIN

Instructor of Electrical Engineering, Thayer School of Civil Engineering, Dartmouth College

SO-CALLED resonance is of very great importance in the operation of wireless apparatus, and every op- erator should have a good working knowledge of the theory of reso- nance and of its practical application. Even the experimenter will work to much greater

employed in the given equation it may be noted first that the numerator E denotes the applied alternating-pressure, having a frequency denoted by / (/ means the num- ber of complete cycles per second). R de- notes the resistance of the coil, exprest in ohms, C the capacity of the condenser in

CONDFNSER

Fig. 1. — The Fundamental Theory of Wireless May be Better Understood by Study- ing This Elementary Alternating Current Circuit, Comprising an Inductive Re- sistance and Capacity Connected in Series.

advantage, with a knowledge of the funda- mental law and its careful application, in making and operating tuning coils and similar devices.

When a coil, consisting of a number of turns of insulated wire is connected in series with a condenser, and an alternating pressure applied to the terminals of the arrangement, as indicated diagramatically in figure 1, the alternating current in the arrangement indicated by an ammeter con- nected as shown may be exprest by : E

I =

farads, while L denotes the so-called co- efficient of inductance of the coil, exprest in henrys. L depends upon the square of the number of turns of wire of which the

amount of energy. The symbol t denotes the value of 3. 1416.

It is instructive to note that if the con- denser be removed from the circuit and a direct-pressure be applied to the terminals of the coil, the direct current may be ex- E

prest by I = — ; that is, according to Ohm's R

law.

Now, by looking at the first equation it is evident that the last equation may be obtained from the first when the numerical

1

value of 2irf L is made equal to .

2irfC

When such numerical relationship obtains in any case, then resonance is said to exist.

The value of tt is, of course, a constant at all times and the value of / is definitely fixt for any given circuit. It is, therefore, apparent that with a given fixt value for

1

2"7Tf Lj a similar numerical value for

277"/ C

may be found by varying the value of C. The value of C for any condenser depends upon the number of sheets of dielectric used in making the condenser, upon the kind of materia] the dielectric consists of, upon the size of the dielectric sheets, and upon a numerical constant which is depend- ent upon the kind of units employed in ex- pressing size or area, and thickness.

I\ • I 2irf L —

27T/C

If a direct current pressure, having the same numerical value as the alternating pressure be applied to the same arrange- ment, the ammeter will show no indication at all ; the condenser, having a very high resistance, really prevents any direct cur- rent from passing. Of course, a direct current does exist while the condenser is being charged, but this is so small the or- dinary ammeter will seldom indicate this minute momentary current. With an ap- plied alternating pressure, however, the result is very different ; since the con- denser is very rapidly charged and dis- charged, the ammeter indicates the pres- ence of the current continuously.

Considering now the different symbols

INDUCTIVE

RESISTANCE

K

CON DENSER

Fig. 2. — This Alternating Current Circuit Should Be Carefully Studied by All Radio Students, as It Contains Similar Elements to Radio Circuits, i. e., a Variable In- ductive Resistance and a Capacity or Condenser.

coil the

* This article especially prepared for the "Elec- trical Experimenter."

rig 6

Diagram Representing the Generation of the "Sine Curve" — the Form of the Average Alternating Current Wave.

is composed ; that is, of two coils of same general shape, the one having twice as many turns as the other will have four times the inductance.

Also a coil having an iron core will have very much greater inductance than the same or a similar coil with- out the core. When, as in wire- less work, it is desired to employ very high fre- quencies, coils, having no iron cores are used, since they may be magnetized and demagnetized very quickly and without absorb- ing an excessive

The capacity of ordinary condensers made up of sheets of dielectric and metal plates, may be exprest by :

C = .000,000,000.224

An

k farads.

In the equation A denotes the area of each dielectric sheet in square inches, n the number of sheets used, k the so-called specific inductive capacity of the dielectric, and t the thickness of each dielectric sheet in thousandths of an inch; that is, in mils.

The coefficient of inductance of a coil having an iron core may be approximately exprest by :

Air n2 A b X 10"

henrys.

May, 1918

ELECTRICAL EXPERIMENTER

33

in which 7r has its usual value, n denotes the number of turns of wire wound on the coil, A denotes the area of the hole thru the center of the coil, exprest in square centimeters, and b denotes the length of the coil (not of the wire), exprest in centi- meters.

Returning to the consideration of the initial equation, and restating the condition

for resonance as when 277/ L = it is

27T/C

evident that the equation may be changed to ;

1 '

2irf C = .

27T/ L

The reason for the latter arrangement of the equation is because it is much easier to construct a coil to produce a variable inductance than it is to construct a con- denser to give a variable capacity.

Considering the last equation, it is evi- dent that if 277/ C has any given numerical value, with a definite value of frequency (value of /) then some value may be given L, so that the numerical value of

1

shall be equal to the numerical value

27T/L

of 2tt/ C.

l/OWf?_

ffg. 3

lomf cond

Fig 5

} fndi/cfive res \ y r=-. *

omfcond.

Fig 4

Diagrams Showing Effect of Resonance on E. M. F.'s in Different Parts of A. C. Cir- cuit; Also Simple Radio Circuits Used for Comparative Study.

the ammeter indication decreases, and if depends upon the numerical value in volts the contact be moved toward the right of the applied pressure, and upon the re- from this position, the ammeter indication sistance in ohms of the coil or part of the

Every True Alternating Current, of Any Shape Whatever, Is Made Up of a Certain Number of Simple Sine Curves Added Together. The Heavy Line Represents the "Resultant" Wave Form, Produced by the Addition of the Three Sine Waves Indicated in Light Lines. These Component Curves are Called the "Harmonics."

also decreases.

To make the matter clearer and more concrete, it will be well to assign definite and practical numerical values to the var- ious symbols in the last equation. Let us suppose the frequency / of the applied al- ternating pressure is 60 cycles per second ; then 277/ is equal to very nearly 377, Suppose further that the capacity C of the

1

fixt condenser is 10 microfarads or

100,000

(.00001 farad). One million microfarads are equal to one farad. According to this assumption 277/ C becomes equal to 377 X 1 1

. Next suppose that = .00377.

100,000 277/ C

1

Then, since 277/ — 377, L =

377 X .00377

= 0.703 henry.

If, therefore, a condenser having a capac- 1

itv of - - farad is connected in series 100,000

with a coil having an inductance of 0.703 henry, then resonance obtains in the cir- cuit for a frequency of 60 cycles, and the current in the circuit is a maximum. The numerical value of the maximum current

coil that is connected in the circuit.

Suppose the pressure is 110 volts and the ohmic resistance of the wire on the coil is 10 ohms, then under the conditions of resonance mentioned, the current will be 110 + 10 == 11 amperes.

A very striking and important phenome- non should be noted at this point, namely, the numerical value of the drop in pres- sure between the terminals of the coil and also between the terminals of the con- denser. The drop in pressure between the terminals of a condenser when resonance

/ 1

obtains in a circuit is exprest by I •

\ 277f C

which in the case under discussion is equal 1

to- 11 X = -915 volts (approxi-

.00377

mately). The pressure drop between the terminals of the coil may be stated by ;

I \R2 + (277/ L)2 which is numerically

equal to 11 \lfj7+ very nearly. This

(377) 2 = 2915 volts; condition of affairs seems a bit uncanny. It does not look ex- actly logical that the pressure between the:

(Continued on page 59)

If a condenser having a definite fixt vah"? of capacity C be connected, as shown in figure 2, in series with a coil so arranged as to allow a different number of turns of winding to be introduced into the circuit as desired, then the physical apparatus will fulfill all of the variable conditions possible, with a fixt frequency /.

Looking at the proposition from a slight- ly different standpoint, suppose the con- denser in figure 2, has an unchangeable value of capacity and suppose the contact point P is so arranged as to include in the circuit more and more turns of the coil as the contact moves toward the right. With any definite value of the frequency of the applied pressure, some position of the contact P will be found such that the indication of the ammeter will be a maxi-

mum. If the contact be moved toward the Graphic Illustration of "Resultant" A. C. Curve Made Up of Three Simple Sine Curves, or the left from the position giving a maximum, 1st, 3rd, and 5th "Harmonics."

>

34

ELECTRICAL EXPERIMENTER

May, 1918

Building an Electric Piano Player

By CHARLES HORTON, Consulting Engineer

CONTRARY to the general opinion among amateur mechanics the au- tomatic piano, aside from the in- strument proper, is a comparatively simple thing. There have been developed commercially two general types

tracker bar and magnets take the place of the bellows while a motor drive is provided to turn the record roll.

At first glance the construction of an electric action would appear to be some- what beyond the ability of the Amateur,

Fig. 1. Front View of Standard Piano Fitted with Electric Player, Including Music Roll Translator. Standard Player Piano Rolls Are Used. Current 110 Volts or Battery.

oi player actions, the electric and the pneu- matic. The operation of the latter is as follows: — There is provided a pair of bel- lows arranged to be worked by the feet of the player which supply the air to run the motor for moving the record and for strik- ing the notes. These bellows do not, as would naturally be supposed, compress air to operate the mechanism but rarefy it; in other words, the device operates by suc- tion. The use of suction instead of com- pression is had because of the advantage that since with suction the air is drawn in thru the holes in the record, there is a strong pressure on the record causing it to adhere closely to the tracker bar and thus preventing the striking of accidental notes. Thus it is seen that the foot bellows draws air from the reservoir provided, and this suction causes the driving mech- anism to turn the record feeding roll. Whenever a hole in the record comes over the tracker bar, air is permitted to pass in thru the corresponding tube and this air relieves the suction in one of the key-strik- ing bellows, allowing it to spring open and strike the proper note.

So much for the pneumatic type of ac- tion. The electrical mechanism is similar to the action of the pneumatic except that contacts take the place of the holes in the

but a detailed examination of the apparatus herein described will show that there is nothing at all difficult in the work ; but owing to the large number of similar parts the work requires a good supply of patience and persistence. However, the result is well worth the effort, particularly when it is understood that the costs of a commer- cial attachment runs into the hundreds of dollars.

The arrangement here described is simi- lar to the commercial electric mechanism but is very much simplified. The record is driven by a small hand-crank (or may be driven by a small electric motor) by means of which, also, the tempo is con- trolled while the ordinary pedals of the piano are used in the regular manner. The loudness may, if desired, be controlled by a simple rheostat and when one has had some practise in the manipulation of the apparatus, one can get very nearly perfect expression from this simple instrument.

The apparatus takes the form of an ob- long cabinet which is adjusted just above the keys of the piano and is held in posi- tion by its own weight. The record read- ing mechanism (translator) is mounted 'on top of the same as is clearly shown in Fig. 1. There is provided one magnet for each key of the piano and one corresponding con- tact on the tracker bar.

The apparatus plays the standard paper music rolls which range in price from ten cents to several dollars and permits the reproduction of all the standard music at a very low cost.

The construction of the simplified ap- paratus will now be explained in detail. Referring to Fig. 2 in connection with the following description the arrangement of

Top View of Group of Twelve Electro- Magnets for Playing Keys of One Octave on Piano.

May, 1918

ELECTRICAL EXPERIMENTER

35

parts may be made clear. This view is a transverse section of the box containing the striker magnets. A represents one of the white piano keys, B one of the black keys and C the supporting board for the magnets. All the striking magnets are mounted on this board which is screwed to the two side strips 4, in order to prevent it bending under the weight. A detach- able top S is screwed to these two side pieces, which arrangement allows easy in- spection of the striking mechanism. Ref- erence to Fig. 3, in connection with Fig. 2, will serve to make clear the arrangement of the magnets, etc. This illustration is a view looking down on the top of the striker box, and delineates part of the top board broken out to show the arrangement of the magnets. There are, of course, seven white keys and five black ones to each octave of the piano ; consequently twelve magnets have to be provided for each oc- tave. One magnet is mounted above the center of each key and in order to find room for so many magnets they have to be arranged in the manner shown, i. c, in four rows.

Each magnet consists as shown of a brass or aluminum tube, detail 6 (this tube must not be iron) on each end of which is forced an iron washer 7. Brass is best for the tube 6, so that the iron washers may be soldered on. The end near the lower washer 7 extends downward, thus form- ing a projection which enters a hole in the supporting board C. The bobbin formed by the tube and the two washers is wound full of number 18 double cotton covered mag- net wire, thus forming a solenoid for ac- tuating the keys. The magnets are secured to the supporting board 3 by means of sev- veral lA" iron stove bolts 9, which also, to- gether with the iron washers, complete the magnetic circuits. Within the tube 6 is ar- ranged to slide freely the iron core 10. and screwed into the bottom end of this iron core is a long brass screw with a round head which is covered with chamois to form a hammer as illustrated in Fig. 2. When the circuit containing any one of the mag- nets is completed, current flows around the bobbin 6-7, and causes the iron core 10 to quickly move downward, thus strik- ing the corresponding piano key. As will be seen by examination of the detail draw- ings, the entire bank of magnets is divided

Side View of Electro-Magnets With Padded

into seven groups, each group consisting of seven white-key strikers and five black-key strikers. This arrangement is advisable in order to make the assembling easy and also permits the correct placing of the strikers above the keys without extremely accurate layout work.

In Fig. 4 is shown a front view of the record carrying mechanism, usually called the translator. This is to be mounted on top of the striker box and contains a free moving stud D, and a free crank-shaft E, between which the record roll is caught ;

Front View of "Translator" Which Controls Circuits of All Key Magnets, the Contacts Being Opened and Closed Thru the Perforations of the Standard Music Roll.

Plungers for Striking Black and White Piano Keys.

a tracker bar F having on it one contact for each magnet ; a comb G having one finger for each contact; and a receiving roller H for receiving the paper roll as it unwinds. The record roll is placed be- tween D and E by pulling D to the left against the spring and placing the right- hand end of the roll against the screw- driver-like crank E. The comb G is then removed from under the heads of its re- taining screws by slipping it upwards and the end of the record led over the tracker bar F and fastened to the receiving roller H, by slipping the ring in the end of the record over the little hook /. The comb is then replaced with its fingers bearing on the paper record and the receiving roller ro- tated slowly by turning the crank K. Now when the holes in the paper record come- under the fingers a contact will be made and the proper magnets will receive cur- rent and strike the proper keys. When the record is finished the comb is removed and the record re-rolled by means of the crank E (or by motor, if one is used for playing the piano). The tracker bar and the comb are mounted on an independent board, the construction of which is shown clearly in Detail No. 26. This board is arranged to slide sidewise in the main translator box for this purpose. The paper has a tendency to work over one way or the other on the tracker bar and thus tend to get the holes out of alignment with the comb fingers, causing imperfect reproduc- tion, in which case it is necessary either to shift the record or the tracker bar. In this mechanism we shift the tracker board 24. This motion is usually very little and is tended to with the left hand on the knob M. Reference to Fig. 5, at the right, will make clear how turning the knob one way will slide the tracker bar and comb to one side, and turning in the other direction to the other side.

(To be concluded )

36

ELECTRICAL EXPERIMENTER

May, 1918

Experimental Mechanics

By SAMUEL COHEN

BEFORE the novice can begin to handle the lathe it is essential for him to become familiar with some of the odds and ends of the parts of the machine. To begin with there are several cutting tools which he should understand very thoroly, as each one

Showing How the "Center Gage" Is Used in Testing a Lathe Center While Being Turned or Checking Up for Trueness After Considerable Wear.

of them is for a definite purpose. The amateur must also know how to sharpen these tools, in order that they may give the best results. All of these problems will be taken up in order.

The first thing that experimental- ma- chinists should see to is that the lathe cen- ters are running true. These are made of tool steel ; the one in the revolving spindle is usually soft, because it turns with the work which is to be machined. The one at the tail stock is hardened. This is done because the article to be machined revolves on this center and causes constant wear. A good plan is to test occasionally the true- ness of these centers. In Fig. 1, a center is shown being tested for angular slope by means of a center gage. It is very im- portant that the end slopes to a 60-degree angle. In order to machine any round stock article between centers of a lathe, it is necessary to determine at first the centers on both sides of the article, then to drill and countersink each end so that it may revolve on the centers with ease.

There are several ways of centering a round piece, and two of the simplest and best methods will be considered. The first one is to employ a combination square, as shown in Fig. 2, and carefully scratching across the face of the work with either a pencil or scriber two diameters at right angles. The point of intersection of these two diameters will be the center of the cylinder. A center punch is set on the point of intersection and driven into the metal until a good indentation is made. This method will be found to be very useful and helpful, as it is the simplest and quickest. The only additional tool required is the combination square, and one can be bought for a nominal sum.

The second method of centering is to use the lathe itself. Fig. 3 shows how this is done. The article in question, A, is firmly secured in the live chuck of the headstock and a drill chuck C, with a proper arbor, is secured to the spindle of the tail stock D. A special centering drill B is secured in the drill chuck. By setting the main chuck holding the article and carefully bringing the centering drill to