MAY, 1908 60CCRN No.2

PRICE 10 CENTS MAY, 1908 60CCRN No.2. &\14ECTRSCS

Published by MODERN ELECTRICS PUBLICATION,84 West Broadway, New York, N. Y.

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IN THIS NUrIBER. 100 WIRELESS TELEGRAPH ODDITIES 7110111k Pit:// P4 By Signor Marconi. 4,0 4 THE DEVELOPMENT OF WIRELESS TELEPHONY , Ifi 4 By Newell A. Thompson, Jr. 0. r 111; TESTING A MODERN ELECTRIC 141 10*. 40 .41 LOCOMOTIVE to r..- By J. Stuart Freeman. tell -arri\LI* 4 ilk AN ELECTRIC SUN ALARM By H. Gernsback. ?t 1 " A SILICON DETECTOR 1 By A. C. Austin, Jr. CONSTRUCTION OF WAVE DETECTORS. A LONG DISTANCE WRITER. WIRELESS AROUND THE WORLD. THE DYNAMOPHONE. ELECTRICAL PATENTS OF THE MONTH.

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". VA 0141.Y-- -.- 7 1La Wen LIZ 5,54S Y ill j It I "TheElectrical Magazine for Everybody" MODERN ELECTRICS

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MODERN EL] CTRICS can only grow by having a very large order to obtain same we offer the premiums listed below. Anybodycirculation who k. the value of these articles will understand how much we sacrifice get a large amount of new subscribers The offer is good only for this ino7th.t6in order'" order at once as only a limited amount of pren.iums is on hand.

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LIGHT ,,,0 Most fascinating nov-dry cell.Develops a surprising amount 104),l4.4110 elty on earth. Comesof power.By reversing magnetit Without question the indifferentdesigns,will run in different direction.The Z Head, best on the market ilia:....-,24::-Z110,,_iiii...4 slickest motor ever produced. s..."4:ei...,...:,.--,,e,..% Horseshoe. Crescent.Price, 45 Cents. By mail sc extra. to -day. Guaranteed ,,,.'''-...."--,'s,,,Z,--7`...'.-----....,,,,,,,-.... Heart shape, etc. for to,000 flashes. In- etta--,-...tt,-..s...- Works with any flash -

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$1.50 Knapp Electric Power Plant FLASHLIGHT59c Type "S" Dynamo. SemiEnclosed. 6 Volts, 4 Amperes. 1 All up-to-date features Agents, here is your chance. i in. pulley for belting to any drivingpower. The ever -ready Electric Will run Motors. ElectricRailways, Flashlight a 11 coniplete, Charge Storage CellsElectro-plate, retails at /1 50Gives 3 000 etc.PRICE, $15.00.Shipping flashes.Each 59cPost- weight, 61 lbs Hand DrivingDevice age extra 10c. Catalog free additional /s.00; Shippingweight, 16 lbs.Noiseless.Easy to operate. JOHNNELSON ELECTRICAL CO. Send 2C. stamp for Dept. Z. 32 -page Catalog. Kewanee, III. Knapp Electric & Novelty Co.,517 W. 51st St., New York When writing please mention "Modern Electrics." When writing please mention"Modern Electrics." "Modern Electrics" guarantees thereliability of its advertisers. NI )I) N E I, F.CTRICS SEND FORIT ELECTRICITY' BluePrint showing Morse,. Bliss Electrical School isoleo hie 10c. WIRELESS CODESContinentalandNavy Codes best school in tell A. C. AUSTIN, Jr., HASBROUCKHeitairs, N. J. exclusively. Students actually construct Dynamos, Motors Y$1 . a .so.° . in Graduates hold good positions thrnodu . E, world.Sixteenthyear opens September 2,. Y OU NEED IT 1 Catalog toBLISS ELECTRICAL SCHOOL, foiltort When writing please mention "Moit,111:leetries." 2131 (I Street, Northwest, Washin.,,_110. When writingplease mention "Modern Electric: WANT A GOOD ELECTRICAL BOOK ? Practical Telegraphy Look Over This List. Price JO Cents Each Taughtby expertsatmy se.hool. MY 1 Dynamo 15 Toy Motor one araduatIna qualified operators. 2 Telephone 10 Electric Bell practical, copyrightmethods. Good mTelle.,: 3 Motor 17 Telegraph Instrument Living expenses earned while learning.Easy payments 4 Storage Battery 18 Wind Armatures respondence course if desired.Catalog FREE. S Wimsnurst Machine 10 Wind Field Magnets Geo M. Dodge.Pres. 0 Magneto 20 Ammeter Dodwe's Instituteof Telegraiihy, 7 Medical Coil 21 Thermostat 6Eighth Street, VALPARAISO, IND. :tied 8 Pocket Accumulator 2Z Motor Rotation li. 9 Plunge Battery 28 Electric tioldering Iron When writing please mention "Modern- Electric 10 Voltmeter 24 Electric Heater 11 Galvanometer 25 Electric Furnace 12 Hand Dynamo 20 Hand Feed Arc Lamp 13 Talking Machine 27 Jump Spark Coil MODELS-- 14I II. P.Dy namo or Motor 28 Rheostat Recent 2:se. Books101 rrausformer 103 Condenser Experimental andElectrical Work Inventions Designed and Perfected. New Bulletin on Rough Castii gs for Dynamos and Motors wit? High Class Exhibitand Working Models. hr sent with any of above.Also Catalog ,±f Bloks on Electricity ModelSupplies. Patterns, Dies, Tools, Gta. and Mechanics' Write for Catalog. BUSIER PUBLISHING COMPANY, 84 LYNN, MASS. WAGNER MODEL WORKS, OFFICEaWONCS 19 MONA WK Si., When writing please mention "Modern Electrics."

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ye If you wish tosell or NeW exchange anything, do Whenwriting pleasemention "MoC;id°8:eilanreSnt6:15..%°'Ilieer:VI;Cler:11i not fail to advertise in If you wish to buysomething classified"ad's"(see don't know wheretogetit, page 73.) ,000 people ModernElectrics read this paper. All information givenfreeof emodernI*" When writing please mention "Modern Electrics." When writing pleasemention Modern Electrics" guarantees the reliability of itsadvertisers. MODERN ELECTRICS

Vol. I. MAY, 1908. No. 2. Testing a Modern Electric Locomotive BY J.STUART FREEMAN.

The Famous " 6000." In the eighty years of the develop- We board an electric car at Schenec- ment of locomotives for long-distancetady, N. Y., the home of the electric transportation, only a dozen years 'or soengine, and go west through the Mo- passed since the electric locomotive hashawk Valley. We have to ride but three been in the field.But fourteen yearsmiles when our car, running parallel to ago no such thing had been heard of,the New York Centraltracks,gets and, while thesteam locomotive of to-abreast of the eastern end of the well- day is the resultof three-quarters of aknown and much -feared third rail, with century of invention and improvement,itsfamiliarsignsatshortintervals, the presentperfection of the electric lo-reading: comotive has been reached after onlya decadeof experimental and research DANGER. work.For some ofus who are more or LIVE THIRD RAIL. less familiarwith them the novelty has begunto wear off, but there are hun- Here we see one of those silent, mys- dredsofengineers who would placeterious bulks of iron, standing quietly great valueupon a trip on one of them.and with no puffing and blowing, as in For thoseof my readers who the case of a steam engine, impatient to the less are among scribeafortunate, Iwill attempt to de-be off, but with a majestic silence, tell- tripon one of these moderning us of vast power pent up within it Rail Eaters." and but temporarily subdued. 42 MODERN ELECTRICS

No. 3424 Making 79 Miles PerHour.

Continuing up the valley,we look outshown in the illustration, which,in tune of the window, and are allowed but agives off a direct current ofbut 6k few seconds in which to catch a glimpsevolts, which current issupplied to ti of the once still engine now devouringthird rail, paralleling the track outside. the track on which it runs at an enor- But the engine is awaitingus now mous rate of speed, and soon becominghaving been stopped byone of the eD invisiblein the distance, although weployees, so we must hurry aboard. First are running in the same direction at 50however, the conductor must take as miles per hour.Soon, however, we ar-pass so as to protect himself in as anything should happen to us.He fink all is right and signals to go ahead. Th bell clangs forth a few strokes and th "engineer," who is a motorman, sloi opens his "throttle." Slowly,steadih, and with almost no sound, we begin t move.The motorman does not hold lever on the first notch, but quickly pull it over the entire first set, of which the: are three, and the motors continuet accelerate perfectly smooth until no their limit of speed under that set,whe he gives them additional "juice." Starting 'from the western end, Interior of No 3424. have a straight stretch of three-quartc of a mile, at the end of which arese: rive at Wyatt's crossing, the location oferal sharp, double. curves.Alonghe the sub -station and barn. Here we awaithe is not allowed to exceed aspeed the return of the engine, and in the65 miles per hour for safety's sal*' meantime wander about the station. This is rather fast traveling, afterPei; High up on one side of the wall thehaving gone faster than about 60 ri, 33,000 volt lines enter fromthe outside,per hour, and we wonder atthe c:4 and immediately below are the curiouslywith which our steed takesthe C1111 shaped lightening arresters and the long,leaning far over to the inside.50_' slim main switches.Down on the floorwhen standing erect we are 10deg;; are a set of transformerswhich reducefrom the perpendicular.At the eTl_i the curve she rights herselfand s1°, the alternating current .of 33,000 volts to on g a much lower potential.From these theleans in the opposite direction current runs totherotary converter,around the next curve. (Continued on page 72.) MODERNELECTRICS 43 A SiliconDetector BY A. C.AUSTIN, JR.

About a year ago the writer had the The illustration .herewith shows all opportunity of examining a Pickhardtthe receiving apparatus, except thetun- Silicon Detector, and after listening toing coil "A" being the detectorproper, it in operation, decided to buildone him-"a 1" is the silicon and "a 2" the brass self.The operator, a friend, explainedpoint resting thereon, "B" is thecon- the action of the detector in detail,say-denser and "C" the telephone receivers. ing in part there wereno batteries to run"T" are leads to the tuning coil, thence down,thatthe adjustment was very/ to the aerial switch and aerial, and"G" easy, and when once adjusted it couldthrough the same switch to the ground. be depended upon not to get out ofor-"-The materials forthis detector may der, and that the connectionswere verybe obtained from any good supplyor simple. importing house, and directions forcon- { From his explanation the instrumentstruction are as follows : (1-Lereinafter described)was built, at a Procure a wooden base suchasis cost of about $3.00, and was afterwardused for pony relays, same to be of the tested on one of the Fall River Linedimensions as shown inFig.I; bore steamers, where it proved to beso sen-9 holes, as per Fig. I, large enough to sitive that wireless telephone could beaccommodate 8/32" screws, countersink- heard with it. ing them 3/16" so as to accommodate A silicondetector, when used withwashers and screw heads, and thencut telephone receivers woundto L000 orthe grooves for the connections, making 2,000 ohms resistance, isas sensitive, ifthem of sufficient depth to allow the in- not moreso, than the electrolytic de-strument to setflat when completed. tector, and itdoes not get out of adjust-There must also be six small binding ment easily. However, telephonesposts to set in holes "a," "b," "c," "d," wound toa high resistance must be used,"e" and "f." forwithoutsuchtelephonesthead- Procure a piece of hard rubber %" vantagesare not so appreciable. thick and trim to size 1%" x i 27/32" The writerhas experimented with aand bore holes as per Fig. 2, "g" and "h" number ofdetectors, among them theto be large enough to accommodate 8/32" Carborundum,of which a description screws.Alsotworound -headbrass will begiven in screws 8/32" thread, about 3/4" long. mercury, a later issue, the carbon - microphonic,etc.,butfinds Make a piece of brass of the dimen- them allfaulty at times, con detector while the sili-sions shown in Fig. 3.Get three nuts stant, seems to be the most con-8/32" thread and three washers tofit sensitiveand satisfactory. the three last-mentioned parts. ELECTRICS 44 MODERN

Al ilor. 2 di 3 4- iy.e. S 9/.5 6- 7 *6. $1,.

Hiream. *4

6 fls 4, 177; A.E. Alo . P49q. Procure a piece of brass372" longpearance, as shownby Fig. 5. N" thick, IN" Bore a hole Y8- indiameter, as sh (this allows for wastage), in Fig. 5, throughthe boss, and wide at one end andY2" wide at the shown, other, and make up as perFig. 4. through the side of same, as a smallhole, threaded with any cony Also another piece of brassY4." x 72" set sc x 7c and bypinning and soldering orTent. small thread, and put a side of thein same so as toclamp the adjus brazing, fasten to the upper the silicon. mentioned,brass point which rests on IN." arm of the support just (To be continued.) rounding the corners tomake a nice ap- A NewBattery keeps the zinc cylinderfrom shifting, The accompanyingengraving is not a close to harmless though depolarizer comes quite new-fangled bomb, but a zinc (up to3/16") to reducethe inter powerful new battery.It is a German surprisi is in everyresistance.It is therefore not invention and the construction that a cell beingonly 6" highand 3 respect wellcarried through. amperes think that a wetdiameter furnishes about 4o The inventor seems to short circuit.The depolarizerused is cell is better than adry one-a beliefmixture of oxide of manganese(9851 which we share withhim. and finest flakegraphite. When exhausted thevent e, issimpli opened and the cell can.be rinsed refilled with aso!' with boiling water; of 20:: tion of sal -ammoniacand chloride the battery will workagain aswell when new. The cell comes withthe exciting to 3,11 filled in container andall one has it up with cleanwater,wh is to fill 1' immediately afterwardsitis ready use. The vent stopper alsopresents an In the April issue,under "Recharging channelat showed why suchcells feature.It has a fine of Dry Cells," we point where ittouches thewall effective, and as willbe seen the provided tolet are not hole; this channel is in 3 German constructorhas produced some-the gases which aregenerated thing real logical. The odd shape ofthe glass containerbattery. MODERNELECTRICS 45 The Dynamophone BY H. GERNSBACK. \\-ehileconducting some experimentsthe vibrations should closea certain cir- in wirelesstelephony I made the discov-cuit, which in turn could be relayed, to eryof quite an interesting combinationtransmitorstartpower,has always ivhich, to my knowledge of the art, hasproved a failure on account of the vibra- not been tried up to this date. tions of the diaphragm, created by the To produce mechanical effects direct-human voice, being exceedingly weak. ly, man, is obliged to exert his muscular My arrangement, as described below, forces. by bringing his muscles in con-to transmit or start power, etc., simply tact with the object to be moved, orby talking into a transmitter, will there- through an indirect way, namely, by in-fore be found novel, especially ifitis terposing a tool between the muscle andconsidered that thetransmitter is not the object.This tool might bea leverconnectedwiththereceivingstation or itmight be a telegraph key, whichwhatsoever.The transmission is made latter, if desired, will move or disturb theby means of wireless electric radiations. far-off object through another medium, No new apparatus being needed in my electricity. arrangement, any amateur can easily per- To apply power to an object the handform the experiment. is used more than any other part of the Referring to plan, M represents the human body; the foot probably rangescommon transmitter as used on most tel-

next.The whole body, mostly appliedephones.R isa.fairly sensitive pony as a lever, follows.The head is prac-relay of seventy-five ohms. C is a con- ticallynever used at all.The lungs aredenser to absorb excessive sparking ;I, used verylittle comparatively, forin- induction coil ;S, oscillator balls. stance in glass blowing, etc. The tension of the adjusting spring H The voice hasnever been used, no caseon the relay should be just sufficient to beingon record that a motor or a dy-keep the armature away from contact namo was started solely by talking, to G.With a little experimenting the right or througha medium.I am, of course, well tension will be ascertained. aware that by talking in a trans- By talking medium loud in the transmitter the telephone diaphragm at the in same will be other endwill vibrate, but that can hard-mitter, the resistance ly be calledpower, it being proved thatvaried accordingly and the armature will In most cases thevibrations of are-close the circuit at G, through battery B' ceiver diaphragmmeasure less than one -and coil I, which may be a common one - five -thousandthsof an inch. To provideinch spark -coil not deprived of itsvi- a contact on thediaphragm in order thatbrator. (Continued on Page 70) 46 MODERNELECTRICS

We are proud tosay that 60o letters received, out of therewas notnal that did not containcongratulatio MOCCRN a few nice words. We were a little "shaky" we did not 'know if we hadat fi ELECTRICS right, but the avalanche stru of kindI received encouragedus enormously, we know now that we do A Magazine devotedentirely to thefear for the future. not hay Electrical Arts. We know that "MODERNEL PUBLISHED MONTHLY BY TRICS" has come to stay,for the Modern Electrics Publication ple reason that itfills a long -felt NEW YORK CITY, N. Y. and because "we have thegoods !"

H. GERNSBACK, EDITOR. A strange disease is spreadingrapid` Subscription Price: For U. S. and Mexico,over this country and threatensto $1.00 per year, payable in advance. fect every young manover 15 years ok New York City and Canada, $1.25. No antidote has been discoveredso la Foreign Countries, $1.50 in Goldagainstitsravages,andparents Stamps in payment for subscriptionsnot ac-greatly alarmed, the new diseaseat cepted. same, time taxing pocketbooks and ch Checks on out of town Banks cannot beac- books heavily. cepted unless the usual exchange is added. The name of the infecting germ Bugum Y-erlessum and creates the SINGLE COPY, 10 CENTS. called "Wireless Craze." The disease incurable. Forms close the 20th of the month preced- Never before was the"craze" ing dateof publication. Advertisingrates stronglydevelopedasthisyear; on application. countable cases are reported from Po The Editorisalways pleasedtoreceive land, Me., to Portland, Ore., and t contributions of timely interest pertaining to statistics show that out of five your the electrical and the affiliated arts.Articles men two are infected. with good draWings and clear photographs especially desired.If accepted, articleswill be paid for on publication, at regular rates. 'No manuscripts will be returned unless return Since'' MODERN ELECTRICS postage is enclosed. made its appearance a month ago,ti' Address all communications to: Editor has been flooded with mail. Fro` MODERN ELECTRICS PUBLICATION the hundreds of congratulatinglettC 84 West Broadway, New York, N. Y. received 159 (one hundred andfit nine) up to this writing deal withnc6 Copyright, 1908, by MODERN ELECTRICS ing but Wireless.Most readerswisho PUBLICATION. the"WirelessDepartment" enlarge some even went as far and askedus I Entered as Second Class matter March 31,publish nothing but Wireless, agill: 1908, at the New York Post Office, under the Act of Congress of March 3, 1879. many wanted a description of anelectr, lytical Detector, while an equally1ar: Vol. 1. MAY, 1908. No. 2. audience wanted to build a Silicon tector. "MODERN ELECTRICS" has had We had in mind to print a good111311 such an unparalleled successsinceitsinteresting articles besides the ones first appearance that it became necessarythe"WirelessDepartment,"but d't to give up the old offices and move tomotto is :"To print what ourreadreacle., larger quarters. We are now located atWANT, not merely what strikes 84 West Broadway, in the very heartEditor's fancy." of New York's electricaldistrict, and We remembered this in timeand tj' our presentfacilities are adequate topresentissueof "MODERNEL/ keep pace with the rapid growth of theTRICS" proves that our motto is noI magazine. boast. MODERNELECTRICS 47 A Long -DistanceWriter BY OUR BERLINCORRESPONDENT.

The writerhas had the good fortunetelegraph or telephone line and there- to -dayto witness some interesting testssulting current variationsare recorded made withMr. Gustav Grzanna's newin the receiver. "Fernschreiber"(long-distance writer.) The problem was to transform these The inventor, a young German fromvariations into writing, and itis here Berlin-Steglitz, exhibited his apparatuswhere Mr. Grzanna hasshownhis at the"Zoo -Hall" in Berlin.The newgenius. "Fernschreiber"hasalso beentested One end of the line is connected toa lately by the German postal authorities,sensitive electro-magnet.If littlecur- and extraordinary results were obtainedrent is sent out from the sender, thereby transmitting handwriting, sketches,ceiving electro-magnet is magnetized lit- etc., by wire from Berlin to Dresden, atle; if much current is cut in, the electro- distance of 15o miles. magnet is energized more, etc. A little mirror fastenedon an iron foil is hung up in front of the pole of the electro - magnet ;this mirror moves around its horizontal axis and willmove more or less, according to how muchor how little current is sentout from the sender. A beam of light froma small 4 -volt tantalum lamp, concentrated througha lens, is directed upon the mirror andis reflected in such amanner that it traces a vertical line, long or short, all depend- ing how much the electro-magnet isener- gized.A vertical move at the sender consequently reproducesa vertical move The characteristicjerks and anglesat the receiver. which are experienced withother sim- ilar apparatusare completely eliminated. The writingis reproduced in every instance with astonishingaccuracy, even sur%r7r0Vrka-(A. on lines Soo miles long.Distance hardly affects theinstruments at all. 49evj Mr. Grzannahas solved the problem to reproduceaccurately in an extremely clevermanner ; Original Message. in the his method is described following lines: The in whichengraving shows theinstrument the sender andreceiver are Combinedall inone. Two such appara-rur -9jrn-ofen-eA-6-- tusare connected each other. with two wires among JeL4 Three wiresare really necessary, but forthe third used. one the ground is As the Instrument Reproduces it. cA_ lead pencil isfastened toa lever in thb a way that it In the circuit, which is controlledby e writing will move lightlyoverthe horizontal movements of the pad.It can sender, right,tothe left, move to theanother small electro-magnet isconnect- This up or down. leveris arranged ed at the receiver, exactly like theother °Creitrintgw,otheresistance so that it slidesone just described.Only thisone has spools.During theits mirror arranged in sucha way that tmrientSaretranorsmei,tttherespectivemove-it can only trace horizontal lines,as soon ed througha regularas the electro-magnet is magnetized. 48 MODERN ,ELECTRICS

The two light beamsare reflected indown, emerges from the such a manner that they fall machine upon thewhile moist one can readthe writing' same point ;as soon as the magnets arewell as ifit had been jotted in operation the lightrays trace linespen. down" and curves upona band of sensitized The instrument works photographic paper. automati These curves andallonehastodoisthe lines are nothing else than thecompo-and the receiving ofa message.wrj w nents of the original writing and eachthe apparatus is connected with ther and every moveat the sending stationular telephone line, quitea good deal, must be accurately reproduced at the dis-business can be transacted by thisto tant receiver. od, which would be quiteimpossible Thesensitizedpaperafterpassingany other way.Large business through thefixing tanks, hoth 10 secondswill undoubtedly soon adopt thesew after the original dispatchwas writtenderful "Fernschreibers."

Demonstration of Electrical Lines ofForce

While it is comparatively easy to dem-then placed in the centre of the disk, onstrate a magneticalfield with ironthe + and- wire are connected to the filings by strewing them on a piece ofdischarge balls of a small static machine. paper and place the magnet or magnets Before the machine is started the plate directly below the sheet, successful linesmust be covered with a film of small of force made by the electrical currentlight particles which should be long an. itself have never been obtained hereto-thin, not round. fore. After innumerable trials Mr. Fischer found that crystals of gypsum gave the best results, besides having the advantage of being cheap.It is to be recommende to prepare different grades of powder a few experiments will be the best guide If the machine is started the crystal, will arrange themselves in certain de- finite lines which demonstrate the electric cal lines of force. Not too high a tension should be u in connection with these experiments, it will tend to scatter the crystals fr their true lines ; irregular figures or 11 at all will be the result. To Mr. C. Fischer belongs the honor If the machine is too powerful o of discovering a method toaccomplishmay keep the rods A and B a littled this, and as will be seen, the arrange-tance away from the tinfoil disks,will ment is simplicity itself. currell To demonstrate an electrical fieldofwill reduce the strength of the and + somewhat. either + and - poles or + It only takes a second or two toobtail poles,etc.,paste twostrictlyround circles of tinfoil about 1-13/in diametercharacteristicfigures. It mayhaPP6 on a clean paneof glass (see illustra-sometimes, that the lines do not0 tion).The distance these tinfoil disksquite symmetrically; in that casesin11),, should be apart must be ascertained bytap the glass plate lightly with awood; experiment. stick while the machine is in operativ" The glass plate itself is placed on an insulator such as a glass vessel, hard rubber, and even four small bottles will If you need a "shake-up," walk on do.Two thin metal rods A and B arethird rail.-"Figs." MODERN ELECTRICS 49 WirelessTelephony BY NEWELLA. THOMPSON, JR.

At the present time there are threeelectro-magnetic methodsof induction method. A well-known transmittingvery good example oft thismeans of the speech wirelessly.They are (1) byatransmission of speech iscross talk in a beam of light, or as it is more commonlytelephone system; words spoken radiophony ; ( 2 ) on one 'mown, byelectro-wire being heard in the telephoneon a magnetic induction ; and (3) by electro-second parallel wire.At the St. Louis magnetic waves. Each one has been fully tested, and it is safe to predict from theExposition Mr. M. R. Hutchisongave an excellent demonstration of thissys- results and data obtained that transatlan-tem.Fig. 2 sh6ws his apparatus, which tic wireless telephony will follow closely upon the heels of its sister, wireless telegraphy. The theory of the first method isby no means new,it being identical with Professor Bell's photophone whichwas invented in 1878.Since the invention of Fig. 2 the selenium cell and speakingarc, theis simplicity in itself.The transmitting range of this system has been greatlycircuit consisted ofa large wire cable, increased by Ernst Ruhmer, it beingonlyA, in series witha microphone, B, and limited by the curvature of the earthandbattery, C.The portable receiverwas a coil, D, of wire 3o cm. in diameter, in -;-, several layers, in series witha small condenser, E, and a telephonereceiver, F. On speaking into the transmitter,B, an undulatory current rotates throughcoil, A, thus setting upa magnetic flux, the lines of which link with the coil, D,and by its inductive action producesa mo- mentary current in the telephone circuit. V The radius of this apparatus,however, is limited by therange of the lines of Fig. force emitted from the transmittingcoil, which is practically one-half of itsdiam- a smoky atmosphere.Ruhmer's appara-eter outside.Of all the three methods tus is shownin Fig. 1.In speaking into the transmitter,the oscillating current of themicrophoneA,issuperposed by means oftransformer B, on the current supplyingthe arc lamp C, thereby causing theamount of light radiated to vary. Theparabolic mirrorD, sends out these rays paralleland throws themon the con- cave mirrorE, of the receiver.There, beingconcentratedon a selenium cell P. theycause the batterycurrent to vary SO thatarticulate the telephone speech is reproduced in receiver G.Ruhmer has carriedon many Fig. 3 method, experiments by this those in this one is by far the simplest for th andFalkenberg 1902 between. Berlin arrnany, and of Wannsee Lake,amateur experimenter, its success being alimy,where hecommunicated up topositive within its limits. cially of fourkilometers, beingespe- Soon after Marconi bridged the Atlan- worthyof note. Letus now tic wirelessly, attempts were made every- turn ourattention to thewhere to transmit speech by the same 50 MODERNELECTRICS methods, but these amounted tolittle, Fig. 4 shows the receivingdevice owing to the low frequency current usedthis system.The keynote to its sue,,.I in transmitting.Electro-magnetic wavelies in the "audion," an invention oil telephony has only of late become a pos-de Forest.This apparatus is three .1 sibility by the invention of various de -as sensitive thanany receiving d known. The "audion" is simplyan eh

tric light with two platinum wingsse inside.The oscillations impingeon antenna and affect the audion throti the transformer circuit.The chant amplitude of the oscillations varies resistance of the gas ionized by the 14 of the filament in the lamp, and causes the diaphragm of the telepii receiver, T, to vibrate, reproducing at ulate speech.This system has met wl instant success from its debut on L Erie last summer, where it was used Fig. 4 report the regatta of the ciation.' The messages were transmit( vices to increase the frequency ofthewith great accuracy and no transmitter enough to carry the vibra-were met with. tions of the human voice. Among the experimenters in thisline are Dr. Lee de Forestand Professor Reginald A. Fessenden.The system of the former is now well known,since the United States Government hasequipped nearly all its vessels with it,which are now encircling theglobe. The de Forest transmitting apparatus is shownin Fig. 3. A currentof 220 volts is led through choke coils, A, thesepreventing high frequency alternatingcurrents from passing; then to the oscillator,B, which is an arc maintainedin the flame of analcohol lamp. From the oscillatorthe high fre- through the con- Fig. ti quency current passes has denser, C, and primary,D, of the air The United States Government One side of the sec-cently placed an order with Dr.de core transformer. of ondary of thetransformer is connnected.est for a large number ofsets apparatus, which is a sure signthat 7: '7747774. less telephony has come to stay. Professor Reginald A.Fessenden, hisimmense stationatBrantP, Mass., has developed a systemof w excee _L less telephony that has given ly promising results.Its theoryis p T tically the same as Dr. deForests tern, but his apparatus isentirely ent and far more simple.Figs. 5 illustrate his methods.In thetray ter, Fig. 5, A is theexcitationNvi.a -Iv- 0 of alternator, B.This alternatoris of the most wonderfulpiecesof Fig. 5 tricalapparatuseverconstructea proves false the oftenmadestag' to the antenna;the other to ground 0.1 through a microphone,E, which variesthat a high frequencyalternator the amplitude of theemitted waves ac-considerable output is an cording to the voicevibrations. This alternator is a smallmachin( MODERN ELECTRICS 51 with a thin fixed armature Morley type, A NEW SPARK GAPFOR WIRELESS. and revolvingfield magnet with three hundred and sixtypolar projections. An A new methodto obtain more regu- alternating currentof 150,090 cyclesperlarity of dischargesin connection with secondandban E. M. F. of 65 volts iscondenser circuits has beeninvented by obtained at the speedof 139 revolutionsa German electrician, Mr. W. Eickhoff. persecond.Even at this high speedno It is well known thatthe starting of trouble is experienced with the machine.the discharge in the sparkgap is some- From the alternatorthe high frequencywhat irregular if condensersare used ; current is led through the transformer,in other words, the dischargedoes not C, which makes the emitted wave sharpalways take place just when it oughtto. and persistent.The microphone, D,is Mr. Eickhoff usesa brass rod and files located in the antenna at a potential nodea fine point at the free end.The other where the voltage is only about 15.Theend is solderedor connected by other resistance change in the microphone, D,means to the negative terminal of the varies the current and in proportion tospark coil, as shown in sketch. this variation the potential of the antenna rises and falls; therefore, the radiated waves vary in amplitude in proportion to the changes in the resistance in the microphone, D. Professor Fessenden's receiver is identical with the electrolytic detector used M.E. in wireless telegraphy (see Fig. 6), the antenna being grounded througha tuning inductance, A, and primary, B, ofa If the distanceis well selected, the transformer, the secondary, C, is incir-intensity and generalappearance of the cuit with the electrolyticcell, P. spark is not changed;the regularity of With this apparatus workingat its fullthe discharge, however, is increasedover capacity, ranges ofover too miles are tOo%. available.During thesummer of 1906 INCREASING THE EFFICIENCY OF communicationwas daily carried on be- SPARK COILS. tweeen the BrankRock station and a small schoonerup to distances ten miles An interestingdiscoveryhasbeen off shore.During the winter followingmade by an Englishman, Mr. A.Henry. furtherexperimentswere carried on be-He found that when heconnected two tweeen BrantRock and Plymouth. LastWehnelt interrupters in serieshis Y2" year a stationwas erected in New Yorkspark coil would give sparksup to 5Y4", City. andcommunication isnow easilywhich at this lengthwere even more in- carriedon between that point and Branttense than the original '72" spark. Rock,a distance ofover two hundred By means of rotating mirrors itwas miles.Owingto its extreme simplicityfound that the frequency of theinter- operation, ruptions were 30o with this system isvery promis- one Wehnelt in- ing.The terrupter ; by using two ofsame, the fre- flaming operator hasno spark -gaps or -arcs toconstantly adjustor re-quency ran up to 600.If the two inter- hus makingtransmission absolutelyrupters are exactly alike, one observes in r'quiet, quitea contrast to the so-calledthe rotating mirror that the platinum "thunderfactories" points get red hot alternately. Summing of Marconi. up briefly the Itisquite interesting, too,that by success, littleusing two such interrupters in series three it maybe, obtained by these the methods,ds efficiency of a coil is greatly increased. telephonynhon, o, itseems that wireless hascome It was found that while withone in- i` willeventuallyome to us to stay andterrupter and 90 volts across the pri- dreceive be developedso as to send atMessages mary and 8.5 amperes, the sparks ob- by the human voicetained were I/"" long, but by using insteaddistancesand withgreater speed two of by signalsas at present. interrupters with the same voltage, 5y4" sparks were obtained, and only5 am- We'a\ketrsotiTywire is peres were required. tiS no sti onger than its No results were obtained by usingtwo 'e FPs." Wehnelt interrupters in parallel. 52 MODERN ELECTRICS An ElectricSun Alarm BY H. GERNSBACK. o thosewishing to rise with the suntially translucent form, and when ch morning the apparatusdescribed into the light it will be found to have this article is to be recommended. Clark red color.In this statethe ment is non-metallic and a di-electric, The present paper also tellshow to e make a SELENIUM CELL, as quite afewfact, it has a good many properties of readers requested the description ofsuch.cheaper brother-glass, whom itres bles a good deal while in its vitrous A good many readers not beingfamiliar s with selenium, a few wordsabout its If, on the other hand, we melt sel characteristics and peculiarities will noium and letit cool off very slowly, cooling to doubt be welcomed. willbe found after ha Selenium is an element and wasdis-changed into a crystalline form of a s covered by the famouschemist, Ber-gray color.In this state itis a m zelius, in 1817.It takes its name fromand conducts electricity as such.It selen-the moon.In its crystalline formnow also opaque tolight. the element is a metal. The construction of a selenium cell by no means an easy task, as the me only works. successfully when applied another metal in form of an extreme thin film. It is quite hard, too, to establish good contact between a seleniumfilm a other metals and a good deal ofpatien is required. A good seleniumcell,however. worth while spending time upon, as most interesting experiments canbe a formed with it and newresearches carried out. As selenium has a veryhigh res ance, even in itscrystalline form,it Fig.i. necessary to offerthe current numer of a succes In 1873 WilloughbySmith acciden-paths in the construction tallydiscovered the peculiar propertycell. that selenium changed itsresistance by of merely exposing the metal to a source A light. While experimentingwith selenium sticks, which he used asresistances on a troubled a good telegraph circuit, he was Fig2 deal .by fluctuationsof the current,for ma account. On careful A very good type ofcell easy to which he could not is shown in Fig.I ;a andb repres investigation he foundthat when the feetlon he had placedtwo brass strips,each about 2 cover ofthe box in which i/i6" thick and %"wide.In the the selenium wasclosed, the current was broken line deal weaker thanif the box wastration b, is shown in a a good thefacilitate the study. open. Furtherresearches established Next, the brass stripsmust beW fact that theelectrical resistance of se- r the amount of thepolished on the -edgesand no lenium varied with The stripsshe'd light which falls uponit. places must occur. thenbetinnedevenly-anoperat Commercial seleniumusually comes in Y If it is heated suf-which any plumber canperform for the form of sticks. This tinning is necessary, asit has ficientlyitdevelops strong, poisonous, t which smell quite likefound that seleniumadheres better dark -red fumes, tinned surface than tobrass. horseradish. We now cut a stripof heavypar After being meltedand cooled off and Y," wide. quickly, selenium assumes avitrous, par-ment paper 24" long MODERN ELECTRICS 53 we placebetween the two prepared brassthe temperature a andb (not shown in illustra- should be reducedas strips, quickly as possible.Slow cooling will tion), andproceed to wind the stripsgive bad cells. into anoval spiral.It is of theutmost importance that this, winding is done ac- The selenium cellis now ready foruse, curately, as the finished spiral must beand to prevent itssurface from being absolutely smooth and straight on thescratched or damagedit should be paint- face wherethe selenium is to be applied.ed with a thin layerof a very clear solu- A steel squarecan be usedto goodtion of shellac in alcohol. advantage;itwill greatlyfacilitate to If the cellis well constructed it will obtain a smooth and even surface. have a resistance ofabout boo to 700 Two oak boards which have a connect-ohms in the dark.In full sunlight this ing plate, c c and d d respectively, andresistance may fall belowSoo ohms. which are in metallic connection with two The writer constructed cellsas per binding posts, A and B, are now con-above description, which wouldring a structed and the completedspiralis bell througha relayif a match was

clamped between these boards by meanslighted near it in the dark. of the two bolts, n n, as shown in illus- The selenium cellcan be put to a tration.The brass strips, a' and b',con-variety of uses; the best knownone nect with the plates, c c and d d, re-probably is found in Prof. GrahamBell's spectively. radiophone,in which transmission of The idea of the parchment strip is tospeech is effected bymeans of light rays separate and insulate the metal stripswithout wire connections.This was the from each other effectively, and if a tele-first wireless telephone. phone receiver, in series with battery is A beam of light is thrownupon an now connected to binding posts, A andextremely thin reflecting mirror insuch B, not the slightest sound should bea way that the reflected rays from the heard.This shows that the insulation ismirror fall upona distant selenium cell. perfect. If one speaks nowon the back of the After the face of the block is well pol-mirror, same is made to vibrate, andthe ished and absolutely smooth and straight,beam of light changes in intensityac- it is ready to receive the film of selen-cordingly. A telephone receiver in series ium, which is best done in the. followingwith the distant selenium cell records manner: all these changes and in thismanner the The whole arrangement is placed invoice is reproduced clearly. an iron vessel, the bottom of which is Selenium cells have also beenfound covered with clean, dry sand. We nowuseful in connection with telescriptors, pour sand all around the cell so that onlythat is, instruments which transmit writ- the polished surface remains uncovered.ing, drawings, photographs,etc., by wire. We then place thevessel over a Bunsen The electric sun alarm iseasy to con- burneror on a hot stove and let the cellstruct and the connectionsare effected, heat tilla selenium stick, when tried, willas shown in diagram - Fig 2. melt freely. Assoon as this temperature C is the selenium cell which iscon- is reachedthe vessel should be taken fromnected in series with about 8or 10 dry the heatand the selenium stick should becells and a 75 -Ohm or, better,150 -Ohm rubbedover the entire surface of thestandard relay, R, which must be adjust- prepared faceof the block.It is of theed as fine as possible. Amere breathing utmost importancethat as thin a film asagainst its armature must close thecon- possible isobtained, as the completed celltacts, G.The local circuit (light lines) willnot be sensitiveat all if too muchconsists of two dry cells in series with seleniumis applied. switch S' and alarm bell, B. As soonas the selenium is well dis- .The selenium cell is placed ina box tributed,the vessel with the completedwhich has a glass cover, to prevent the cellmust be placedin a tin or othercell from being damaged. The complet- illmetal boxand the cell baked inan ovened cell when wired up (use flexible cord) forabout half called an hour.Attentionis is placed on the window sill and inclined maintainto the factthat it is necessary toin such a manner that the face which Fahrenheitthe temperatureat 250 degreeshas the selenium filmis directed sky- during thistime.After thatwardly. , (Continued on Page 71) L....____ 54 MODERN ELECTRICS J Driiartuirtit Wireless Telegraph Oddities By SIGNOR GUGLIELMO MARCONI. "On Nov. 27, 1901, I left forNew-it would be possible to send, messages foundland with two assistants.As itacross the Atlantic Ocean with the same was impossible at thattime of the yearfacility with which they were beingsent to set up a permanentinstallation withover much shorter distances. poles, I decided to carry outthe experi- "About two months later% in Febru- ments by means ofreceivers connectedary, 1902, further tests were carried out 'to elevated wiressupported by balloonsbetween Poldhu and a receiving station or kites-a systemwhich I had previ-on board the American liner Philadel- ously used when conductingtests acrossphia en route from Southampton to New the Bristol Channelfor the British PostYork. The sending apparatus at Poldhu Office in 1897. was the same as that used for the New- "It will be understood,however, thatfoundland experiments.The receiving when it came to flying akite on the coastaerial on the ship was fixed to the main- mast, the top of which was 6o meters ofNewfoundlandinDecember,this method was neither an easy nora com-(197 feet) above sea level. When the kites were got "As the elevated conductor was fixed fortable one. and not floating about with a kite, as up, muchdifficulty was caused bythe producing con-in the case of the Newfoundland experi- variations of the wind ments, good results were obtained on a stant changesin the angle andaltitude causing correspond-syntonic receiver, and the signals were of the wire, thereby by the ordinary ing variations inits electrical capacityall recorded on tape and period ofelectrical resonance. Morse recorder. Poldhu, in Cornwall, "On the Philadelphia readable mes- "My assistants at sages were receivedfrom Poldhu up to England,had receivedinstructions to December I1, duringa distance of 1,551miles, 'S's' and other send on and after oftest letters as far as 2,099miles. certain hours everyday, a succession signals are followed by a short message,the "The tape records of the `S's ' in my possession, and someof them whole to betransmitted at a certain pre- alter-are hereexhibited to -night.The dis- arranged speed everyten minutes, received are minutes' rest. tances at which they were nating with five allverified and countersignedby /the "On December 12the signals trans- of the ship, Cornwall wereclearly re-Captain and chief officer mitted from in manywho were present during thetests. ceived at theprearranged times, interest, succession of `S's'being heard "A result of some scientific cases a incon-which I first noticed duringthe tests on distinctly,although, probably the very of the weaknessof the sig-the Steamship Philadelphia, was sequence variations in themarked effect of sunlight onthe propa- nals and theconstant great dis- receiving aerial, noactualgation of electric waves over height of the tances. could bedeciphered. I wasof message day we wereable to "At the time of these tests "The following the opinion that this effectmight have result.The signals were the confirm the and by my as-been due to the loss of energyat actually readby myself transmitter by daytime, causedby the, sistant, Mr.G. S. Kemp. dis$lectrification of the highlycharge° result obtained, although "The imperfect apparatus, wastransmitting elevated conductoroperated achieved with by the influence of sunlight.I am now convince meand my co- of sufficient to permanentinclined to believe that the absorption workers thatby means of due t° stations not dependentelectric waves during daytime is stations-that is, sustaining thethe ionization of the gaseousmolecules, on kites orballoons for light' conductor-and by theemploy-of the air affects-{ by ultra-violet elevated and as the ultra -violet rayswhich eror ment of more powerin the transmitters MODERNELECTRICS nate fromthe sun are largely absorbeda given direction upper atmosphere of the earth, can be obtained than in the can be obtained allround by means of itis probablethat the portion ofthethe ordinary aerials. earth'satmosphere which is facing the contain more ions or electrons "When this typeof aerial was adopted sun will at Glace Bay,a considerable strengthen- than thatportion which is in darkness, ing of the received signalsat Poldhu was and theretore, asProf. J. J. Thomsonnoticed. tais illuminated and ionized It was, therefore,decided to has shown, adopt the directionalaerial at all long- air will absorb someof the energy ofdistance stations. the electric waves. "A further improvement "The fact remains that clear sunlight introduced at Cli f den and Glace Bayconsisted in the and blue skies, though transparent toadoption of air condensers, light, act as a kind of fog to powerful composed of insulated metallicplates suspendedin liertzianwaves.Hencetheweatherair at ordinary conditions prevailing in this country are pressure.In this manner itis possible toprevent the dissi- usually suitable for long-distance wire-pation of energy due less telegraphy. to losses caused by "The operation of the long-distancethe dielectric of thecondensers previous- stations in England and America made lyemployed, anda very appreciable it possible to transmit messages to ships,economy in working, resulting fromthe whatever their position, between Europeabsence of breakages of thedielectricis and North America, and to the Cunardeffected.These air condensers, which have been inuse since May of last year, Company belong the credit of havinghave been entirely greatlyencouragedthelong-distance satisfactory. tests, a circumstance which enabled them "After considerable timeand expense to commence, in June, 1904, the regularthe new station at Clifden was got ready publication on their principal vessels .offor tests by the end ofMay, 1907, and experiments were then commencedwith a daily newspaper, containing telegraphicGlace Bay. messages of the latest news from Europe "The messagescan now be transmit- and America. ted across the Atlantic by "This dailynewspaper has now been day as well adopted by nearly all thelarge linersas by night, but there still exist certain plying to New Yorkand the Mediterra-periods, fortunately of shortduration, when transmissionacross the Atlantic is nean, and it obviouslyowes its entire ex-difficult, and at times ineffective istence tolong-distance wireless teleg- unless raphy. an amount of energy greater than that used during what I might "In some ofmy earliest experiments call normal in 1896 I conditions is employed. used copper mirrors, by the "Thus in the morning aid of whichit was possible to project and evening, a beam of electric when, due to the differencein longitude, radiation in a certaindaylight or darkness extends direction,but Isoon found that this only part method would of the way across theAtlantic, the re- tances. only work over short dis-ceived signalsare weak and sometimes "About cease altogether. threeyears ago I again took p the subject, "It would almostappear asifillu- and was able to deter-minatedspacepossessedfor ine thatby means ofhorizontal aerials, electric isposed in waves adifferent refractive indexto ossible a particular manner, it wasdark space, and that in consequence the to confine theeffects of, electric ayes mainly electric waves may be refractedand re- sired. to certain directionsas de-flected in passing fromone medium to True, thelimitation of transmission toone direction the other.It is, therefore, probablethat defined, is not very sharply but it is these difficulties would not beexperi- nevertheless very useful.enced in telegraphingover equal dis- "Thepracticalresult of this method °e'en so far tances from north or south,or vice that messagescan beversa, as in this case the passage from sdeerIsiretodverconsiderable distances in thedaylight to darkness wouldoccur almost only cil_rections,while they travel over other omparatively simultaneously in the whole ofthe me- directionsi short distance indium between the two points. moderateheand that. with aerials "In the same manner ght, greater a storm area in efficiency inthe path of the signals often bringsabout 56 MODERNELECTRICS a considerable weakening of the received America, there is no longerneed for waves, while if stormy conditions pre-doubt. Although the stationshave vail all the way across the Atlanticnoworked for only a few hours dailvy ;ceft interference is noticeable.Electric wave945 words of press andcommercial shadows, like sound shadows,may besages had been transmitted formed by the interference of reflected across ocean by this means up to thetid-e waves with the direct waves, wherebyFebruarylast,sincetheservice signals may be much less effectiveor im-opened. perceptible in thearea of such electric best judges ofa wave shadow. w those who have madeuse ofit,a "In the same manneras there exist ar among newspapers the chief usershave periods when signalsacross the Atlanticbeen the New York Times and sc the L ,, are unusually weak, there exist otherdon Times, which have already cc public]; (yr conditions,especiallyatnight,whichexpressedtheiropinionofthis make thesignalsabnormallystrong.inetnocl of communication. PC Thus on many occasions ships and sta- "Whether the new telegraphy willor tions equipped with apparatus of a nor-will not injure or displace the cablesis mal range of 200 miles have been ablestill a matter of conjecture, but inmy to communicate over distances of overopinion it rests a good deal on what the it,000. This occurred recently, when acables can do in the way of cheaper rates, ship in the English Channel was able "Whatever may be the view as to it to correspond with another in the Medi-shortcomings and defects, 'there can be terranean.Buttheimportantfactorno doubt that wireless telegraphy across about wireless telegraphy is that a ser-the Atlantic has come to stay, and will vice established for a certain distancenot only stay but continue to advance. "Cable telegraphy across the Atlantic shall be able to maintain reliable com-was subjected at the commencement to munication over that distance. a series of discouraging failures and sta- "The erection ,of long-distance appointments, but whatever itsdifficul- lc tionsfor the purpose of telegraphingties I think I am not unjust in saying tf across the Atlantic met atthe outsetthat it enjoyed one advantage over wire- with the severe criticism of a certainless telegraphy, namely, that it was free 11 important section of the English tech-from the natural hostility of vested in- nical press, which, although onewouldterests representing over sixtymillions imagine it existed for the purposeof en-sterling, now invested in cables, which li couraging and promoting the progressofrightly or wrongly consider long-distance t electrical science and industry,alwaystelegraphy as menacing their interests. t champion the "In seven years the useful rangeof . seemed more inclined to t particular interests of thecable com-wireless has increased from 200 to 2,500 t be panies. miles.In view of that fact, he will "Without wishing to enterinto anya. bold prophet who will ventureto affirm controversy onthis point, I venture towhat may not be done in seven years predict that some ofthe statements pub-more. lished with reference tolong-distance "Among many people there seemsto wireless telegraphywill make very amus-bearootedconvictionthatwireless ing reading in a few yearsto come. telegraphy is not suitable for thehand- "Long-distancestationsare now inling of code or cipher messages.What" course oferection in many partsof theever gave rise to this idea I do notknow world, the mostpowerful of all beingbut I wish to emphasize that it ispurer that of the ItalianGovernment at Col-fictitious. Code messages can besent tano, and Ihave not the slightestdoubtjust as well by wireless as byordinarY that telegraphythrough space will soonmethods of telegraphy. of affording communi- "I do not wish to claim thatwirel& be in a position er.,: cationbetweendistantcountriesattelegraphy is infallible, and although cheaper rates than canbe obtained byrors do sometimes occur it isabsolutel. any other means. certain that, having regard to the1-01': "As to the practicabilityof wirelessdon and Montreal service, mostof ILe telegraphy working over longdistancesmistakes can be traced to theland such as that separatingEngland fromtelegraph transmission betweenLond"' (Continued on Page 70) MODERNELECTRICS 57 TheSimplest and Most Efficient WaveDetectors and How Amateurs Can MakeThem BY J. STUART FREEMAN. The possibility.of transmitting electric First, we will look into the construc- waveswithout wires has been known totion of a mechanical coherer and de- exist, since Hertz in 1887, performed hiscoherer with which all the pioneer re- well-known experiment with a spark coilsearch work was accomplished. and an incomplete metal hoop.It was Fig. I.-(A) is the top view of one of some yearslater, however, before Mar-these, made on the plan of the original coni gave the world the wireless tele-Marconi type and (B) of the same figure graph, the result of long years of ex-is the elevation of the coherer alone. (C') perimental and research work. This wasis a piece of glass tubing 172" in length, 78"innerdiameter, and ofsufficient strength to withstand the tapping of the metal ball, (I).Inside of this tube are fitted two pieces of brass nicked -plated rod(0' and P')preferably, and as snuglyaspossible. (0')isclamped fast by the binding post (D'), while (P')has a thread on it-orissol- dered tothe head ofa dry battery AB binding post-and can be adjusted by 1 la the nut. (N').After the proper adjustment of thisisobtained, the binding post (B') clamps it in its correct posi- FIG. I_ tion. looked uponas one of the greatest mys- teries of theage, while now, although just as wonderful,it is spoken of with more or lessintelligence by even the layman. A But howmany of the countless mil- lions whohave electricbells, medical coils,etc.,in their very homes, realize that theyare surrounded constantly by theseunseen, silent, mysterious waves of the etherin which they live?For every time a callerpresses our push button and the clapperof the bell vibrates, there are set in motioncountless impulses in the surroundingmedium which, were they interceptedby therightinstruments, wouldsound as loud ing as the distinct buzz- in an ordinarytelephone receiver. But,"you say, "there is the difficulty. Those'instruments' money." cost a great deal of Yes, that istrue in some cases, butitis surprising and how many simple inexpensivedevices the experimenter FIG- g_ hasdiscovered,during thepastfew Experimenters have found that either years, that mirably. willanswer the purpose ad-one or both ofthe rods should be made For instance,the writer hasto slant on the insideend, as shown in messagesn".n of boysin their teens receivingthe diagram.This insures better con- from in Washington,D.C.,senttact of the filings withthe electrodes and BrantRock, Mass.,with no moreadmits of more efficientsetting.The expensivewave detectors writer made in willattempt than those headjusting mechanism the to describe below. its simplest and mosteconomical form: 58 MODERNELECTRI CS

OF) is a piece of bent sheet brass, /a"direct contact with themercury wide, with holes drilled initfor theever, if graphite or carbon elecirode screws and the rod (P')-orbolt, asemployed, no filings arenecessary suggested above-and the set screw (N')electrodes in every caseare run io,y. is taken from a dry battery binding post.until a very faint buzzing sound" The bell (H) is of any type employingplace in the telephone receiver,a a vibrating tapper with a ball(I) onfinely adjusted, thisstyleisespeci the end.The gong is better removed toserviceable. eliminate the unnecessary noise. At (R) Another form contains onlygranu are placed coarse nickel and silver filingsed graphite between carbon plugs. in the proportion of 96% of the formeranother employs aluminum filings electrodes of the same metal. Of the auto-coherers other than trolytic, there is one type in whichp tically no adjustment is necessary. Wheo used in very weak, long-distance worl, 1,2 w success cannot be assured, but inlee tures and experimental work exceeding)} bt w fine results have been obtained with it al Fig. 2 shows a top and front view ot in this form and it will be seen that it w simply a "microphone" coherer. ca

(A) is a solid block of dry, hard woof CC with holes drilled into the front and into th which are wedged two, electric light car- P( FICL bons (B and B').These are filed so to 4% of the latter.To add to the sen-that a cross-section taken near the outer sitiveness of the instrument, the ends ofends resembles an inverted "V" withthe the rods (0' and P') should be slightlyangleslightlyrounded.From these, amalgamated with mercury. wires are run to binding posts (Cand This coherer is one of the simplest andC') on top.To make the instrument most serviceable for the receipt of slowcomplete, a steel darning needle islight messages.Its arrangement in the elec-ly laid across the carbons so thatonly tric circuit is shown in the drawing. a very slight sound is audiblein the tele- For the reception of fast telegraphicphone receiver. messages, and especially for long dis- Of the various kinds ofauto-coherer5 tances over which the oscillations areand methods of adjusting the same,the very weak, auto-coherers shouldbe used.one represented by Fig.3hasbeen In these decoherence takes place imme-proved to be the most reliableby the diately upon the cessation of the im-United States navy, and is nowin 0 pulses.Of the various forms tried, thein most of, if not' all, its landstations electrolytic ones have been proven to be the most serviceable.But, before taking up the latter, we will describe a few of the former that have been given considerable entertainment to amateurs and experimenters. In general the same instrument is used as that representedby Fig. 1-B, without a decoherer.Also the inner ends of the electrodes are cut off squarely, instead of slantingly.And, in every case, the FIG_ 4- tube and itscontents should be absolutely dry. The figure is a sketch of a wavedetecto; In one style a small globule, of mer-made by the writer on the planof td cury, a little less indiameter than theone used in the Washington navyYar ; bore of the tube, is placed in the tubeItis very delicate, thougheasily 31,1e' with a half dozen or so fairly largecheaply made, and, when not in use,tij, pieces of graphite placed on each side toneedle should be raised and theivh,' keep the metal rods from coming intoInstrument shunted from themain MODERN ELECTRICS 59 suit toprotectit from heavy, near -bythe use of principally those of the local a zoo solution of either nitric kr>cillations, or sulphuric acid, andneither of these station whensending. will attack the platinum diagram (A)is a firm base point to any ap- In the preciable degree.In adjusting the in- ith slight ornegligible vibration.(B)strument, the set stiff piece of spring brass Ya" screw (K) is revolved is a rather slowly until the point(E) barely touches in widthand 15" long.One end of thisthe surface of the securely to the base, while electrolyte, which is fastened point is recognized bya faint sound in on theother end is soldered an oblongthe telephone receiver binding post (C) which holds the short in the circuit. In regard to theconnections of theco- metal rod (D), into the end of whichherers described abovein their electrical is soldered a pieceof fine platinum wire circuits, only the generalconnections will (E), sharply pointed. The platinum pointbe given in thispaper. dips into some form of glass vessel con- These areas shown in the diagram, whichexplains taining the electrolyte, supported on aitself. base (G) of hard rubber, fibre or hard wood. The simplest form of vessel isa broken miniature incandescent lamp (F) with a small hole made in the top and all of the filament, cement and protrud- ing lengths of the platinum "leading -in" wires removed, as in Fig. 4.This lamp can stand inits regular porcelainre- ceptacle and from the bindingscrews of the same, wires are run to the binding post (H). 13 /oderifs etri "0"

We are indebted to Mr. V.F. Alder- son of Downs Grove, Ills., for theac- companying picture; we publish it gladly on account of its originality. We only haveone suggestion:If we had been Mr. Aldersonwe would have r placed one of the sweet singerson a "third rail" or on a trolley wire-itwould "sRIREvi. Low and finely adjustable ret- s,stance 'Such as slide -wire. have been a bitmore "modern." TELE As it is, we cannot quitesee where the 1,-.1coNE RECEIV- ER "MODERN ELECTRICS"comesin. cRO,NO FIG. 3_ We even have a suspicion thatAdam already threw his bootor a brick out of the window when his neighbor'scats At aconvenient distance between the base (G) gave a free concert on the fence nearby. and the binding post (0), P.S.-"Fips," ourofficeboy,just some formof anchorage is located forcame in and explained to us that elec- theadjustingrod (N). is an (A' of Fig. 3tricity was not invented at Adam'stime; isometricprojection of one simplewe consequently are forced to take it all form.)Directly above drilled (M) is a hole,back and apologize to Mr. Alderson. in (B) witha hollow bushing (J) solderedover it. If you are easily shocked, don't 1/8" in The brass rod (N) is come diameterand 8" long, with a finetoNew York,you threadon the mightacciden- wheel upper end.The brasstallywalkonthe"BATTERY."- (K) isat leastI TA" in diameter"Fips." arid isthreaded around so as to revolve easily the rod(N) on the thread. Itis simple to invent anew trolley Thiscompletesthe instrument exceptwheel ;-a dozen are patented each for the electrolyte week Very in the vessel(F).-pretty hard though tosell three of good resultshave been obtained bythem in a year.-"Figs." 60 MODERN ELECTRICS How to RemedyTroublesinWireless Telegraph Instruments (Concluded.) Experimenters and amateurs usuallyof a filings coherer centers inthe film prefer the filings coherer on account ofWe have also pointed out how- - neees itssimplicity and because loud signalsit is to keep humidity and especially are obtained with that type.Audibleor fatty substances from coming in signals are especially desired for dem-tual contact with the filings, but of eq onstration purposes, and the bestwork-importance are the filings themselves, ing detector in connection with thefinest Manyexperimenters have b i,000 ohm telephonereceiver would nat-grieved time and again through the ' urally be of little use indemonstratingpossibility to obtain the right mixtu, wireless telegraphy to a largeaudience,and itis quite surprising to find h or to .a novice, towhom the faint clickmany misleadingarticles are publish in the telephone receiverwould riot con-every year in text-books and in pen telegraphy as wellcals on this topic.The writers in m vey the, idea of space tried their own" as a coherer inparallel with a loud ham-cases probably never

ceipts," or they would have been so mering sounder. filings coherer isconvinced that while, for instance, a fi While the common mixed with a. few fir fairly reliable, it is notpossible to trans-up 5 cent piece, fast as withof a dime, might worksatisfactory f mit with same messages as change qui auto-coherers or detectors.The usualdistance of 3 feet, things coherer is about 12good deal when it comes tosignal o speed of the filings 50o feet or over imile. to 15 words perminute. mixture used On account of this,modern wireless The most common the filings co-nickel and silver in thefollowing stations usually employ 96,silver4 pa only ;themessageportions:Nickel hererforcalling While this mixture worksfairly well detector by ha .proper isread through a pure metals telephone re-short distances, if the means ofhigh resistance been used for makingthe filings,it ceivers.As soon as theoperator hears such a combina sounder, he cuts outthenot be claimedthat the call bell or has ever been usedsuccessfully for filings coherer by meansof a double- thea shortdistance of i mile. throw knifeswitch, which connects The misleadingreceiptspublished antennae to the detector.He then takes traced directlyto after which theaerial isoften are to be the message, and itspatent claimsof the inventors,who, again connectedto the coherer urally wishing tokeep the rightform ready to awaitthe next simply changethe p call apparatus, for themselves, and e message. can onlyportions of thematerials used Of coursethis arrangement substitute differentmetals. where thedistance fromthe occurr be used to affect This isquite a common sending stationis not too great that inventors If the rangebecomesand we cannot expect not al the filingscoherer. for thegive away suchreceipts which itwill be necessary outlay, but too wide, represent a generous ye operator tokeep thereceivers continu-hard work of months,and maybe ously to the ear. on the partof the investigator. we mightadd that the i3 In this instance It may be assumedthat Marconrike, which the filings lc distance with used the per greatest. successfully doesother early workers uite coherer canbe operated silver combination, but wefeel q 300 miles.While Marconi work s' not exceed milestain that forlong distance received signals ontape over i,000 different metals thanthementioned the sendingstation,no distant from could be re-were used. really intelligiblemessages In fact, nickel haslong beendis corded. ed for several good reasons. FILINGS MIXTURES. For coherers it isessential thatCr In a previouschapter of this paper we attention to thefact that theand very sharp filings areused. but have called working may work verywell at the start, whole successof the perfect MODERNELECTRICS 61

jog a verysoft metal, the sparking be-Of course the opening of test tube is to tweenthefilings themselves will soonbe closed witha piece of clean paper and wear awaythe sharp projections and th not with the uncovered thumb. cohererwill be found to refuse working The resulting mixture shouldnow be altogether after ashort while. Alsotested in a coherer, and if found satis- nickel is entirely toooxydizable and willfactory the remaining filings should be soon becovered with oxide, which raiseskept in a small glass vial which had been the resistanceof the coherer in a shortwashed out previously and dried care- time morethan double the amount itfully over the stove.When taking out was atthe start. new filings from the bottle use nothing As a rule filings mixtures are a com-but a clean, rather stiff piece of paper" bination of an oxydizable and an un-bent in V form. oxydizable metal. The unoxydizable one The metals used for making filings as forinstance, silver, serves to decreasemust be pure; alloys, as for instance a the resistance of the mixture and onlyJo cent silver dime, are worthless for a verysmall percentage of same is used.coherers, on account of the admixture of Too much silver, or silver alone, makesother metals used, to keep the silver piece tf a cohereruseless on account of over -from wearing off too rapidly. sensitiveness. A combination which nas been in use When making filingsitis absolutelyfor years, while expensive, gives excel- necessary that a very coarse newfile belent results.It is made by mixing 9a If a new file cannot be obtained,to 95 -parts of gold with 5 to Do parts of used. This has been used success- a an old one may possibly doafter it hasbismuth. fully for long distance work and has a a been soaked in strong ammonia for half an hour and thenrinsed in very clean,ways given satisfaction. hot water and dried over a hot stove. A combination which we have used No results will ever be obtained withfor years and which has the advantage of being cheap and suitable as wellfor a fine file; filings obtainedin such a man- made ner are not sharp enough andresembleshort as for long distance work, is of courseby using a certain kind of softsteel and more a metal powder, which pure silver in thefollowing proportions : is the worst thing that could ever be put (by weight), silver12. in a coherer tube. Steel 88 parts parts.This proportion must be strictly , The metal bar of which the filings are insame will vise.observed;littlechanges to be made must be clamped in a make useless combinations, asonly in In a clean sheet of paper a hole of the mixture will be. size Of the metal is then cut and slippedabove proportions the successful.The steel which we have in over the metal bar.The edges of the and coarse ;fine straight allmind is very grainy paper are then turned up grained, or so-called"smooth," steel does around, to keep the filings from fallingnot give quite asgood results. down.The paper is bent downwardin such a way that the operation of filing does not interfere with the sheet. The filingitself must be practiced. We are somewhatsurprised at the 4i Only long, slow,.powerful strokes of thelack of interestshown in our "Wireless file will furnish good filings ; quick filingTelegraph StationContest."A Three gives too small particles. Dollar, prize for aphotograph is consid- The ideal size ofa filingis about 3/64ered a fair reward.What seems to be to 1/16" thick, the length about 1/16 tothe trouble?If you cannot take apho- 5/64" long.The corners or edgesmusttograph yourself,have somebody else be very sharpand well defined. take it for you.You will alwayshave When enough filingsareobtained ofuse forit, even if wedo not reprint it. each metal, they should be sifted throughIf you shouldbecome a famous man a fine, small hair sieve to separate theduring the yearsto come, youwould small worthless it not to possess filings from thevaluablemostassuredly regret largeones. experiment room of the The good filings must nowa pictureof your be weighedto proportion on a finescale of the past.Again we say : and thenmixed, which is best done byhappy days of the dark, it Get busyand come out Pouring thefilings in a very clean test interest. tubeand shaking thecontentsviolently.is to your own MODERN ELECTRICS Electrical Patents for the Month

1884,501.MEANS FOR MEASURING THE DEGREE OF 883, 241. WIRELESS RECEIVING INSTRUMENT. EXPOSURE OF A SELENIUM -CELL.Airmails Eons, Fammick G. Rssos,tr, Wesfford, Mass.Filed Ma, J. O'CosNoa, St. Paul, Minn. mu .kb, Germany. Filed Aug.1,1906. Serial No. 22, 1007.Serial No. 375,1124. rial No. 394,652. 328,813. 1.In an alarm system of the CIARA described bination, with anelectric circuit and at at,,."!,.°°. 1p 23 controlled thereby, of a separable loop armo,,,,- rite

/pa circuit andadapted,whenseparated,to be pa,;," the articles of merchandise. 1

I.' In a means for measuring the degree of exposure of a selenium cell, the combination with two selenium cells, of two sources of current separately connected with said two selenium cells, a line connecting said two selenium cells, a line connecting said two sources of current in series, a conductor connecting sald two lines, means for ex- 10 posing one of said two selenium cells to the light to be measured, and agalvanometerInsaid conductor and 1. A coherer for a receiving instrument of the class de- adapted to control the exposure of the other selenium cellscribed, comprising a loose. dry mechanical mixture of constant source of light in accordance with that offine particles of zinc and carbon. the first selenium cell. 884,989.WIRELESS TELEGRAPHY.GootintstO MAR- CONI, London, England, assignor to Marconi Wireless Telegraph Company of America, a Corporation of 884,071.SPACE TELEGRAPHY. Sews, Cssor. Brook- Jersey. New line. Mass., assignor to Stone Telegraph and Telephone Original application filed Nov. 28, 1902, Serial No. 132,974.Divided and application filed Feb. 2, 1903, Company, Boston, Mass., a Corporation of Maine.Filed Serial No. 141,399. Dec. 31, 1906.Serial No. 350,257. Again divided and this application filed Feb. 9, 1904.Serial No. 192,730. 1.In a system of space telegraphy, an elevated conductor system comprising a laterally extending conduct- ing surface having Its inner portion cut away and its 883.437. RECEIVER FOR SPICE SIGNALING STS. TEMS. LEONARD D.WILONAN, San perimeterlarge compared withits distance abovethe Francisco,Cal: mirth. Filed July 24. 1906,Serial No. 327.591.

1. Receiving apparatus for space signaling by liertain oscillations, comprising a conductor arranged tobe ex- cited by said oscillations, relatively movable conduction surfaces in close proximity to each other, means normal'', 1.In a wireless telegraph system, the method of detect- ing electrical oscillations of high frequency, which separating said contacts butpermitting contact eh. consistssaidoscillations said in creating a rotating magnetic field at a receiving arereceived on saidconductor, abruptly varying said field Ay the received oscillation;station, means-reastablishing said separation after the Postalgo of and utilising the variations In said field to create each oscillation, and means to damp the movement of gale signals. Intelllsaid surfaces. \ ego

Electrical Inventions for Which Letters Patent Have Been Granted for the Month Ending April 14th.

882,553,882,554. BLOCK -SIGNAL SYSTEM.Fred B. 882.682. COMMUTATOR FOR POLYPHASE CUR- Corey, Schenectady, N. Y. RENTS. Alexander Heyland, BrusselsBelgium. Henry 882,555.ELECTRIC SIGN.Samuel E. Doane, Cleve- 882,687. ELECTRICAL CONTROL SYSTEM. land,Ohio. D. James, Pittsburg, Pa. 882,563. REPEATING FIREARM.Lewis L. Hep- 882,695. SYSTEM FOR AUTOMATICALLY STOP- burn, New Haven, Conn. PING CARS OR TRAINS.EdwardE.Klein- 882,564. ELECTRIC HEATER. Edward M. Hewlett, schmidt, New York, N. Y. Schenectady, N. Y. 882,699. ELECTRICAL RECEPTACLE FOR PLANTS. 882,569. RHEOSTAT.Charles D. Knight, Schenec- Harry S. Latshaw, Jersey Shore, Pa. tady, N. Y. 882,717. COMBINED TROLLEY -WHEEL AND 882,570. BURGLAR -ALARM. CosmoLiaci,New SLEET -CUTTER. Edmund M. Schollenberger, Haven, Conn. Chicago,Ill. 882,573. STORAGE BATTERY.William L. Met:rin, 882,733. ELECTRIC FURNACE. EdwinAppleby Fredericktown,Ohio. Chicago,Ill. INDUCTION -MOTOR CONTROL.Karl A. 882,744. SIGNALING DEVICE. SpencerC.Cart, 882,581.Pauly, Schenectady, N. Y. Spokane, Wash. 882,586.ELECTRICAL RECORDING INSTRUMENT. 882,752. LETTER -BOX ALARM AND INDICATO Lewis T. Robinson, Schenectady,N. Y. OscarF.Erickson,Berkeley,and. Richard 882,602. CONTROLLING -SWITCH.Harold E. White, Bradshaw, Oakland,Cal. Schenectady, N. Y. 882,753. TROLLEY -WHEEL. Daniel D. Grant, 882,606. INDUCTION -MOTOR CONTROL.Ernst F. Pittsfield, Mass. W. Alex.anderson, Schenectady,N. Y. 882,758. FIRE -ALARM SYSTEM.Henry H. Hillier, 888,607. MAGNETIC CLUTCH. Robert Anderson, Pasadena, Cal. Schenectady, N. Y. 882,788. ELECTRIC FURNACE.Albert L.Marsh, 882,610. ADJUSTABLE ELECTRICALRESISTANCE. Lake Bluff,Ill. Frederick 0.Ball,Plainfield, N. J. 882.803. INSULATOR. Leonard W.Storror, Sari CONTROLLING SYSTEM FOR ELECTRIC Francisco, Cal. 882,639.MOTORS. Henry D. James, Pittsburg,Pa. 882,833. TROLLEY -HARP. Frank M. Mudler, Pitts- 882,658. CONTROL SYSTEMFORELECTRIC burg. Pa. MOTORS. Hermon L. Van Valkenburg, Pittsburg, 882,848. SNAP -SWITCH. WilliamM. an3 Pa James H. Wyatt, Philadelphia, Pa. 882,673. LIGHTNING -ARRESTER. Walter T. God- 882,857. SIGN. Edgar B. Wolfe, Newark, N. J. dard, Victor,N. V. 882,872. SYSTEM OF ELECTRICALDISTRSIBco UtTtTON. 882,681. ELECTROMAGNETIC TOY ENGINE. Harry. Rufus N. Chamberlain, Depew, N.Y. G. Hawekotte and Henry W. Klansman, Indian- 882,876. SPARK -TIMING APPARATUS.CharlesC. apolis, Ind. Dodge, Wollaston, Mass. MODERN ELECTRICS 63

882,802, ELECTRICAL. PROTECTIVE APPARATUS. James A.Kenny. Chicago,Ill. mum TROLLEY.Henry C. Reynolds, Portersville, Kaburaturg (tinitet Cal. RESISTANCE -UNIT. LawrenceE.Bar- Ss2,990.ringer, Schenectady,N. Y. 883,007. ALTERNATING -CURRENT REGULATOR. Augustine R. Everest,Rugby, England. Theaccompanyingphotograph is 883,008. THERMOSTAT. CharlesJ.Fox,Londcn, awarded the prize of Three (3) Dollars England. VIBRATOR.Andrew G.Gray,St.John, for this month's Electrical Laboratory s83,013. Canada. New Brunswick, Vernon J. Contest. 583,029. ENGINE -STOP. King,Lorain, Ohio. Numerous photographs were received, VAPOR ELECTRIC APPARATUS. Osias $83,030.0. Kruh, Schenectady, N. Y. but only very few were clear enough for DYNAMO -ELECTRIC MACHINE.John P. reproduction. From these Mr. Kimball's S83,043.Nikonow, Pittsburg, Pa. 883,051 ELECTRICALLY -OPERATED SWITCH. was selected, being the most interesting.. Henry F.Starrett, Milwaukee, Wis. Photographs to be used in this contest 883,062. STRAIN -RELIEVING ATTACHMENT FOR TELEGRAPH -KEYS. WilliamH.Teachworth, should be as clear and sharp as feasible; Waxahachie, Tex. it is impossible to reproduce a "hazy" 883,078. CONTROLLER FOR ELECTRIC MOTORS. Thomas E. Barnutn, Milwaukee, Wis. orover -exposedaswellasunder- Clifford 883,088. TELEPHONE INSTRUMENT. E. Contestants will Cole,Birmingham, Ala. exposed photograph. 883,093. DIVIDED -CENTRAL TELEPHONE SYS- please bear this in mind when sending TEM.William W. Dean, Chicago, Ill. 883,110. ELECTRIC FURNACE. Herman L. Harten- in pictures. stein,Constantine, Mich. VAPOR ELECTRIC APPARATUS. Osias 883,114.0. Kruh, Schenectady, N. Y. 883,150. ACTUATING MECHANISM FOR ELECTRIC SWITCHES. Harry B. Snell, Toledo, Ohio. ELECTRODE FOR THE RECOVERY OF 883,170.METALS FROM SOLUTIONS BY ELECTRO- LYSIS.Samuel B. Christy, Berkeley, Cal. 883,181. ELECTRIC STREET -RAILWAY SWITCH. JohnP.Dowd and ThomasP.Dowd,Cedar Rapids, Iowa. 883,195. SYSTEM OF DISTRIBUTION.David Hall, Norwood, Ohio. 883,200. CONTROLLER FOR ELECTRIC MOTORS. Henry D. James, Pittsburg, Pa. 883,20L TERMINAL CONNECTOR. Harry T. John- son, New York, N. Y. 883,217. AUTOMATICALLY -TRIPPING TROLLEY - POLE MECHANISM.Thomas H. Mars, Chicago, Ill. 883,225. COUPLING APPARATUS FOR ELECTRIC CIRCUITS.Nicholas F. Niederlander,St.Louis, Mo. 883.227. INSULATOR. Edward F. Padden, Chicago, AL 883,242. ATTACHMENT FOR TROLLEY-HARPS. William F. Savage, Columbus, Ohio. YOUNG ELECTRICAL EXPERT. 883,246, 883,247, 883,248. DYNAMO -ELECTRIC MA- CHINE.Robert Siegfried, Pittsburg, Pa. Mr. Irving Kimball, a young electrical AND 883,272. COMBINED FUSED CONNECTOR expert and inventor ofBoston, Mass., LIGHTNING -ARRESTER FOR ELECTRIC WIRES.Frederick C. Woods, Galesburg, Ill. has recently perfected somevaluable and 883,273. TIME -SWITCH.Charles E. Avery, Jersey the elec- City, N.J. highly important inventions in 883,276. ELECTROMAGNETIC MOTOR.Arthur H. trical line. Beard, Memphis, Tenn. Berry, study of the 883,280. LIGHTNING -ARRESTER. Millard He has made a scientific Fayetteville, Ark. electrical transmission andreproduction 883,303. SECURITY LIGHTNING -ARRESTER.Wil- liam E. Drake, Grand Island, Neb. of sound, and his improvedmethods of 883,308. EGG -TESTING DEVICE.Frank W. Gay- lor, White Plains, N. Y. reproducing music have attracted con- 883,310. TROLLEY -HARP. EdwardJ.Harrison, siderable attention. South Bend, Ind. combined 883,311 ELECTRICAL SMELTING -FURNACE.Karl His "VITAPHONE," a A. F. Hiorth, Christiana, Norway. Par- motion picture andsound -reproducing 883,346. INDUCTOR ELECTRIC GENERATOR. nellRabbidge,Neutral Bay,near Sydney,New device, is not far fromperfection. South Wales, Australia, of his "MOTOR- 883,350. COMBINATION SIGNAL ANDTRAIN - The original model STOPPING APPARATUS. AlfredL.Ruthven, PYROGRAPH," an automaticelectri- Topeka, Kans. 883,366. ELECTRIC SWITCH.ArthurL.White, cally operatedpyrograph or wood -burn- Cresco,Iowa. works to perfection. n,,833,389. SWITCH -CLIP.John Clay, NewYork, N. Y. ing machine, '84,397. INSULATOR. Walter T. Goddard and John The illustrationherewith shows Mr. S. Lapp, Victor, N. Y. laboratory desk, and here wIONAL OUTLET-CONDI:11T.John L. Kimball at his 8 3,Kruger,9SNewYork, N. Y. be found long after the ,.,416. ELECTRIC ALARM FOR LOCKS.Frank he can usually f.Merrill, Los Angeles, Cal. clock has passedthe midnight hour. 883,447, CALL -BOX Henry S.Bullock,Jr., New taken by Mr. Kim- ,,,York, N.Y. This photo was " ,484.AMUSEMENT DEVICE.Herbert N. Ridg- with an automatic electric Poston, Mass. ball him -elf \" RATER -HEATER.Adolph W. Schramm. flashlight of his owninvention. Riverton,N. J. (Continued on Page 71) p 64 MODERN ELECTRICS Wireless Signals to be Flashed Around the Globe (Paris Correspondent of "MODERN ELECTRICS.") An interesting proposal has been pre-doubt that the officials and scientists sented to the Academy des Sciences, bythe United States will heartily in Bouquet de la Grye, the famous Frenchthe scheme. endorse scientist. The Eiffel Tower, which haslately been equipped with new, powerful This gentleman proposes to equip the in- Eiffel Tower with such powerful instru-struments, now furnishes rapid andper.

ments that the exact time according tofeetwireless communication withthe Paris or Greenwichcan be flashed toarmy in Marocco; the Government has every vesselafloatinthe world, nonothing but praise for the systemand matter what its position may be. greatly encourages the new art. From the lofty top of the great tower 4 cables are carried down, facing the Avenue de Suffren ; the length of these cables is about 910 feet each, forming the highest stationary antennae inthe world.These copper cables terminate in several sheds in which theinstruments are housed.The officials intend to construct a new, large building on the southwest side of the tower, if the experiments prove successful to warrant the erection of a permanent and costly station. At the present time experiments are also carried on with wireless telephony, a new system being used.It is claimed that telephone conversation can be carried on up to a distance of 8o kilo- metres.No details of the system are available at this writing. Mr. Bianly-the real inventor ofthe filings coherer-has succeeded in direct- ing and manoevring government torpe- does by means of wireless ;the system is astonishingly simple, and it is claimed that these manoevres cannot be inter- fered with by the enemy,-a claim,if true, will be of the utmost value tothe French Government. By prearranged signals either at noon Messages by means of the new system or midnight the time could be indicated,have already been sent as far as Lyons which would enable the ships to learnand Le Havre; uninterruptedservice, the exact longitude without the troublehowever, cannot be maintained so far. to take -observations by the sun. Trials to this effect have already been A cursing,excitedman may be made.It is now a comparatively easycompared withasputtering,dancing matter for Paris to keep up communi-"trolley wire" which fell to the ground. cation withallvessels' equipped withBoth can be easily quietened-but yol,', wireless in the Mediterranean and alsomust know how to go at them -"Figs. part of the Atlantic Ocean. Simon Newcomb, the famous astrono- It sounds paradoxicalto hear how merofWashington,andAlexandermuch hot air a fellowcan transmitover Agassiz of Cambridge, Mass., were quitethe 'phone, especially if there is sleet on enthused over the new plan, and do notthe line.-"Figs." PP44.s., MODERN ELECTRICS 65

ARelayWorking With OneHundred Billionth Ampere

dark.By means of parabolic Up to nowthe most sensitive relaycourse be polarized relay, whichmirror a beam of lightR, is thrown wasthe Siemens upon the smallsuspended mirror on A. closeitscontactswith about towards S, but would .) amperes. This beam is reflected o.00005 by as long asthe foil A, is motionless,the The newselenium relay invenfed fall through the Allstrom is said torespond to lessbeam of light does not Mr. G. 000 000 all(one hundredslot of S. than a 000 However a minutecurrent-such as a billionth) ampere.This would make it the sensitive than a telephone re-wirelesswave-passingthrough even more windings of M, willmagnetize its core ceiver, andexperiments have shown that light mirror work it will soon finduni-sufficiently to turn the very for wireless The instrument wason A, andthe ray can now fallthrough versal adoption. the slot of S, whichreduces the resist- used lately inconnection with electro- This is suf- whichwerealwaysance of theselenium cell. lytic detectors, ficient to operate relayR, which in turn thought successfulonly in connection receivers.Loud, audiblewill actuate bell B. with telephone obtained so far with With suitable meansthe oscillations of signals were never A can be dampened sothat it will return such detectors,but the new Allstrom it possible to usein its original positionimmediately after selenium relay makes the current had passedthrough M. a sounder ortape register with anykind of detector, no matterhow sensitive. This will come as good newsto wire- AURORA BOREALIS. less telegraph experimenters,and' we de- Passengers on thePhiladelphia Enjoy scribe herewith thearrangement of the Nature's Fireworks. apparatus Passengers who arrived afew weeks ago on theAmerican linerPhiladelphia from Southampton werestill discussing when they landedthe aurora borealis which they saw onenight.From 6 o'clock in the evening,when the sun had set, until daybreakthe next morning the entire zenith wasalight with a deep red glow, reflected fromthe giant rays of fiery lights that shot upinto the heavens from the north.On every side of the liner there appeared tobe huge fires that made the passengers onthe promenade deck feel as if they werelooking on at An extremely light piece of sheetironthe destructionof the world.Toward -1.,is hung between two platinum wiresto o'clockthe lights were at theirbright- of the minute diameter of o.000i inch. est,and outlinedtheofficerson the In the centre of the iron sheet a small,bridge to the passengers. very light mirror is cemented. An elec- Captain ArthurMills, the skipper of tromagnet M,which may have aresist-the Philadelphia,told the passengers on ance as highas io,000 ohms,is placeddeck to listen for adull, booming sound immediatelybehind the iron foil, so.thatfrom the north,which always accom- magnet core almost touches theiron.panied the auroraborealis when seen so Some distancedistanceaway asensitivese- far east inmidocean. leniumcell S, is stationed. The cell itself Is enclosed in front a box, which at the Quite a few"short circuits" are neces- hasa narrow slot.A source oflight electrician.- 0,'s placed behind and directly over thesary tomake a successful seleniumcell, and the room must of"Fips.". 66 MODERN ELECTRICS "3.1Citirk-ISItarkz" Brews Your Coffee While You Sleep By M. G. HUGO

If you happen to be a hustler and ifinch in diameter) to a white heat.'chi.''" you must have your coffee ready fiveheat is sufficient to light thesmall ale, minutes after you wake up, the follow-hol lamp A, and in about fiveminute; ing arrangement will be welcomed.Itthe water in the glass flask H, will is entirely automatic and when well con-mence to boil. coni structed, never fails to work : This glassflask has asoftrubber Attach a wire to. the inner frame ofstopper into which fits a glass tube bent your alarm clock and another wire to aintotworightangles,asshown in thin brass strip, which is best glued tosketch.It is necessary that the rubber

the pasteboard dial ;itshould be ar-stopper fits tight in the flask and thatthe ranged in such a way that only the hourglass tube fits the stopper snugly. hand can touchit. The minute hand On a block of wood a coffee machine must pass over it without touching. isplacedwhichcontainsthe usual amount of ground coffee.Instead of its cover, a circular piece of, wood is provided, through which the other free leg of the glass tube passes. Now as soon as the water commence, to boil, enough pressure is created to drive a certain amount of boiling water through the tubing in the coffee pot, and if in five more minutes the alarm goes off and you wake up, all you will have to do is to reach over and pour out a cup of delicious hot coffee. It is to be recommended to keep the Let us suppose you have to beup byarrangement some distance away from 5 o'clock in the morning.In that caseyou-not because there is danger (an the contact brass strip is glued to theexplosionor fire, etc., is impossible)- dial at that point, which is reached bybut because ifyou drink your coffeein the hour hand at 10 minutes before five.bed, you might go back to sleep! The alarm itself is set for 5 A. M. It is understood thatyou will haveto If now at to minutes to five the hourblow out the flame of the alcohol lantp hand establishes contact with the brassas soon as you wake up ; also the batter). strip (thereby closing the circuit), Bat-must be disconnected,or else thealcohol tery B, (4-5 dry cells) will heat the one- lamp will be lightedanew at 5 P. M.°il inch piece, of platinum wire P, (o.008the same day.

No. 2.

Orrilittral _Notts Borax Ioz.,sal -ammoniac 134°I5., rosin 13/4.ozs., powdered andmixed. NON -CORROSIVE SOLDERING FLUX, scrap zinc and cut fine, i6 ozs., commer' No. 1. cial muriatic acid,32 Fl. ozs. Mixallto Add C. P. zinc chloride to 95°purean earthen jar and let stand for to hours' grain alcohol (6 to g ounces)to satura-Then add rainwateri quart; stirthor' tion and shake thoroughly; let standun-oughly and let stand another 10 hour!' til the zinc settles andpour off 4 Fl.Then add glyceriner Fl. oz. and ounces of the clear solution. I% Fl. ozs.Strain through c°; Then add 2 Fl.oz. glycerine and 14ton andfilter through sand orfilt'd Fl.oz. pure grain alcohol(95°), andpaper.This is good for fluxing any kiti shake thoroughly. of metals. Contributed by W. S. PRESTON, Winchester, It'd MODERNELECTRICS 67

4ID r- C

,11...i1 I . c1+,

Queries and questions pertaining to published free of charge.Only answers tothe inquiries electrical arts addressed to thisdepartment will be the benefit of all readers.Common questions willof general interest will be published here for On account of the large amount of inquiries received,be promptly it answered by mail. answers in any one issue, may not be possible to print all the as each has to take itsturn. Correspondents should bear thisin mind when writing, as all questions will be answered either by mailor in this department. If a quick reply is wanted by mail, a charge of 15cents is made for each question.Special informationrequiring alarge amount ofcalculation and labor cannot be remuneration.THE ORACLE has no fixed rate for furnishedwithout promptly as to the charges involved. such work, but will inform the correspondent Name and address must always be given in question sheet must be used; not more than .five questionsallletters.When writing only one sideof paid to letters not observing above rules. answered at one time.No attention If you want anything electrical and don't know where such information free. to get it,THE ORACLE will give you

TO CHANGE DIRECT CURRENT FAN brushes can be cleanedevery five min- INTO AN ALTERNATING ONE. utes, but the grease willcome again. (14.)HERBERT BOWLER, San Diego,Please advise. Cal., writes: A.-You are using too much oilon I have a direct current fan motor andthe bearings.The fast revolution of wish to know how it can be changedintothe armature sucksup every drop and alternating current. gums up the commutator.Use a little A.-Yes, you might try, althoughwevaseline on bearings; oil is suitable only do not vouch thatyou will have success.for large motors having well protected It will be necessary to rewind thearma-bearings. ture with one continuous wire; alsothe CHARGING STORAGE BATTERIES. commutator must be eliminated. On the (17.) WALLACE BLANCHARD, Man- shaft two insulated brassor copper ringslius, N. Y., asks : are fastened on fiber rings, and thetwo a dynamo giving eight volts, wires from thearmature are connectedone ampere charge three storage cells? to the metal rings.Two metal springs 2.-How long would it take to charge or brushes take off thecurrent from thethree cells, each of ten hours capacity, rings.One of the springs is connected to the with four Edison batteries, type "B.B."r field, making themotor series 3.-Where can I get some paraffinpa- wound. per to make a condenser with? PLATINUMCONTACTS FOR ELECTRIC 4.-Why isit that a "Wonder" Al- WHISTLE. ternator will not run on 104 volt alter- (15.) R. SYLVESTER,Bradford, Mass.,nating current in series witha lamp? asks:Would the wire usedto connect A. i.-Yes, although it will take about with thefilaments ofan incandescent10-12 hours steady run of dynamo to light besuitable for thecontacts of thefully charge ten A. H. cells. electricwhistle described in the April A. 2.-About 10-12 hours, but the stor- number?Where foil? .canI buy platinumage cells must then be connected in par- A.-No. allel.Charging in series would not do, You mustuse platinum foil.becausethreestoragebatteries when Sameis obtained houses, from electrical supplyfully charged read 71/2volts, while 4 whichyou will find in our ad-Edison batteries only give '3.6 volts when vertisingcolumns. MOTOR fresh. Charge your cells with 3amperes. COMMUTATOR"GREASES" UP. (16.) A. 3.-There is paraffinedpaper on writes:JoHN ROAKE,Bayonne, N. J.,the market, but not for the purposeyou intend to use it for.You will have to MYmotor takes woven 5 volts, Y2 ampere. Itmake it yourself. Melt some paraffine drum t wire brushes.Armature isin an iron vessel over a very small flame. 4, YPe, 6 slots. e commutator Every time I run itWhen hot enough, dip your paper, which grease gets filled witha kind ofshould be fairly heavy (letter paper), in and stops,the circuit between thethe paraffine and keep it in the fluid till ELECTRICS 48 MODERN Take the A. i.-We referyou to inquiry the bubbles stopappearing. in this issue. paper outand hang up to dry. A. 4.-You will need morecurrent to A. 2.-We cannot tell unless how many revolutions your nlotYor°1114t, la run thealternator.A 16 C. P. lamp, ni4 s, which we presume you areusing, onlyper minute. You need WHAT SPARK LENGTH WOULD P allows 72 ampere to pass. TB, about 2 amperes connect 4 lamps(16 C. COIL FURNISH? This will CLARENCE M. KRUG P.)in bank as per sketch. (20.) Bead. make it work. Pa., writes: C What size spark would a coil give ti. primary being wound with 125 fee' (

No. 18 wire and the secondaryw L000 feet of No. 25 wire? A.-A coil made with a quantity wire as per above directions will har give a jump spark.In the firstpl WIRE FOR SPARK COIL. No. 25 wire is entirely too heavy. Ev long distance wireless coils are hard ( 18.) HARRY C. THOMPSON, Ludlow,ever wound with as thick a wire as N Vt., writes: 3o.Furthermore, 1,000 feet of wire I.-I have about a quarter of a poundthe secondary is a good deal too li of No. 36 double cotton covered mag-Use about Y4.lb. No. 36 D. C. C. w net wire and plenty of such as the sampleand your spark coil will give about g enclosed.If I can make a spark coil ofspark.The primary does not need go this amount of wire, what would be theas much wire .as you state.About best dimensions, length, diameter of core,feet will be sufficient. number of layers in primary? GRAVITY CELLS FOR LIGHTING LA 2.-Kindly explain why zinc chloride (21.) STEPHEN F. RUSNACK, Pa is used in recharging dry batteries in-Ill., writes : stead of sal ammoniac? I.-Please let me know whether gra A. I.-Sample of wire submitted isity cells (blue stone cells) can be u single cotton covered magnet wire No.to light small incandescent lamps,an 14 S. W. G.It is a good deal too heavywhether they can be used in closedcir for a small coil. We recommend N. 18cuit ? or 16 D. C. C. well paraffined wire. You 2.-What is used to keep thelitharge can undoubtedly use your No. 36 wire,and red lead from dissolvingafter the however Y4lb.will hardly give muchplates of a home-made storagebattery over Y4 inch spark. We refer you to ourare formed?Or what would bebest well written book, "Induction Coils andto retain the same in the holes? How To Make Same," by Marshall. A. I.-Yes, but you cannot light ino Price, postpaid, 25 cents. than 3-5 small incandescent lamps, A. 2.-Chloride of zinc has the prop-the high internal resistance ofgravid erty of being hygroscopic, which meanscells allows only very little currentto that it will collect the moisture from the this tY air.It will consequently help to keeppass. Evenlargecellsof any renewed dry cell from drying up toohardly ever give more than 1-10 a,,111, peres.By using the new tantalumto: fast.Besides this chemical, as an excit- used tu, ing electrolyte (in connection with chlo-ment lamp gravity cells can be good advantage ;such lamps useon' rideofammonium,salammoniac) greatly reduces the internal resistance ofabout V4. ampere, against 3/4-1 amPere 11 the cell. the common carbon filament lamp i'ot other words, 4 tantalum lamps d°no PULLEY FOR MOTOR. use more current than one carbontYr:d (19.) ALEX A. AARONS, N. Y., asks:lamp.Gravity cells are of courseus; I.-I. have aI to volt direct currentin closed circuit work. They are hart% fan motor. Howcan I use this on a II()ever used for any other purposetua volt alternating current? just this one. 2.-What size pulley must beput on a A. 2.-Nothing is used to keeplithar54 .one -eighth(1/8) horse power motortoor red lead from dissolving instool, give 2,200 revolutionsper minute? battery plates.The two named6°1 MODERN ELECTRICS 69 cals inthis respect actexactly like port- (b) Is not a resistance sometimes in- land cement.As soon as the cement hastroduced in the circuit between the aerial set-although water wasused to pre-and coherer also? pare it-watercannot dissolve it after- 2.-Where a telephone receiver is used -;vards.It is the same with red lead orto take wireless messages how is the re- litharge.If the right fluid was used toceiving party "called up"? make the paste,viz.: sulphuric acid, gly- 3.-Is not the telephone receiver and cerine, liquidammonia, etc., etc., there-electrolytic "coherer" now regardedas sulting cementwill not dissolve anymore,more efficient than the filings coherer, once ithas set.One of the best liquidsrelay, sounder, decoherer, etc.? to use forpasting either red leador lith- 4.-What is the address of somecom- arge ismade by mixing io parts of liquidpany where I may purchase tubes of cel- ammonia,, 26°, with 2 parts of glycerine.luloid for wireless coherers? The resulting plates are hard and sound 5-Does a Leyden jar(condenser) and do not "shed" when in use.To ob-when connected to the secondary termin- tain a perfect plate it must be porous.als of a spark coil increaseor decrease To that effect, before pasting, mix theits sending qualities?I notice that when redleadorlithargewith 2-3%fine I connect my jar with the coil the spark ground sulphate of ammonium. There-becomes much fatter and more vigorous. sulting paste must be worked quick,as A. i.-(a) This is hardlyever used it hardens soon ;use as little liquid asnow, and we doubt if much benefit could possible.The paste shouldnever flow,be derived from suchan arrangement. it must be stiff and rather hard. Fixed resistances and choke coilsare WIRE FOR ONE -INCH SPARK COIL. used sometimes. (b) Yes. You probably have in mind (22.) ARTHUR H. BLAKE, Philadel-the regular tuning coil tovary amount phia. Pa., asks : of inductance. t.-How many poundsorfraction A. 2.-The answer to this is foundon thereof of No.34 (bare) magnet wirepage 6o of this issue. would be required fora I" spark coil, A. 3.-Yes, the combination issome- whose core is 7/8"x 7", having lb. No.times i00% more sensitive and equally 14 magnet wire in primary? efficient than the filings type. z.-What is meant bytinned copper A. 4.-The Electro Importing Co., of wire? New York City, can undoubtedly fur- 3.-Does the ElectroImporting Co.,nish you with such tubing. New York, carry No. 34 bare magnet A. 5.-The sending distanceisin- wire?If not please sendme the name ofcreased a good deal, as the oscillations of some other reliablefirm who does. condenser discharge are very persistent 4 --Also, what firms sell carbon, suchand do not die away as rapidlyas the as is used in dynamobrushes, to be used for direct discharge of a coil alone. Tuned a microphone detector. circuits must be used, however,on both A. 1.-Abouti to VA lbs. will do, al-sending and receiving stations. thoughwe do not recommend touse bare wire. UseD. C. C., it is less risky. BROOKLYN NAVY YARD'S AERIAL. A. 2.-Platedor covered with tin.It is usedto give the wirea better finish (24.) C. A. 13Rms, Ocean Grove,N1 and to keepit from oxydizing (blacken-J., asks : ing). I.-Is there any difference in thesend- A. 3. --Yes. ing and receiving range ofan aerial wire? A. 4 --EasternCarbon Works, JerseyThat is, could, say, a 50 -foot aerialsend City, N.J., can furnish a greater distance than it could receive, carbons, you with suchor vice versa? or carbons ofany description and shape. 2.-How are the letters A .-. Ch - - - - - 0- - - ;and WIRELESSQUERIES. -- of (2 the Continental code used? Write3s.): M. G. VAN.AUKEN, Ames, Ia., 3.-What is the height of the aerial used at the Brooklyn Navy Yard wire- I'-(a) Whyis a variableresistanceless station? thImesrelay used in thecircuit between 4.-And the height of the aerial (from and thecoherer? the water line) on coastwise steamers, NW -

70 MODERNELECTRICS

such as those of the Clyde and WardD. C. C. paraffinedmagnetwire,o lines N or 15.For the secondaryuse i1/21 A. I.-Yes.If your receiving appa-No. 30 D. C. C.,or, better, ratus are sensitive enough, nothing pre-magnet wire. S.s.1 vents you to receive messages i,000 miles away.If, on the other hand,you have only a i-inch spark coil with which to THE DYNANOPHONE. transmit, the sending distance 'at best will (Continued from Page 45.) only be about I-I/miles.The range of Every time the circuit isclosed a series of sparks will jump at a wireless station does not depend so acrosst much -on the aerialas on the efficiency ofballs at S, creating oscillations. Tht the instruments. oscillations, traveling throughthe 4 A. 2.-A, O and U form part of thearrive at the receiving station,wilt German alphabet.E forms part of thethey impinge on the antennaA and French alphabet (e accent aigu)-sharperate the coherer 0 throughrelay I accent-as in café.Ch is used a goodThe decoherer D is also shown. Re4 deal in the French language.In thiscoherer and decoherer are allopera country, when transmitting telegrams theby a single dry cell L.This is thes4 circuit as in my "Telimco" wireless letters are used separately, viz.: C -h. stl tern.Relay R' has in addition two A. 3.-18o feet. SE tionary contacts T and T', which, wht A. 4.-65-85 feet. the armature Z closes, complete anoth DATA ON ONE -INCH SPARKCOIL. circuit, as, for instance, througha sn motor P, an' incandescent light, etc. (25.)MAGEE ADAMS, Milford, 0., As long as words are spoken in th asks: transmitter M, oscillations will be i.-If a wireless receiving stationis up in S and the receiving station Ai equipped with a receiver usinga tele-work continuously until the voice at phone receiver, is thereany way to call, stops.Motor P will, of course, be kep that is, ring a bellor the like? in motion only as long as the' voice tali 2.-What is the best and most efficientinto M. type of antennae for a small wireless plant using a microphoneor electroly- WIRELESS TELEGRAPH ODDITIES. tic detector ? (Continued from Page 56) 3.-Is there any danger of thesec-and Clifden, and' between Glace Bay a ondary wire in a spark coil burning out,Montreal. except, on an overloaded primary? "I find, however,that probablyI 4.-Please give data for a spark coilgreatest ignorance prevails inregard, .that will give a spark long and as bigwhat is termed 'tapping,' or interceptol around as a lead pencil or larger, thatwireless messages. No telegraph syst Would not use wire finer than No.3o issecret.The contents of everytC B. & S. D. C. C. in the secondary. gram are known to every operator A. i.-We refer you 'to ,"Oracle,"handles it. query No. 23, in this issue. "Nevertheless, there are penaltiesat A. 2.-A mast about 40-50 feet high,tached to the tapping of ateleg4 carrying glass insulators, on which awire, and it ought to be as wellixr kie;.0 p1 bare copper wire, No. 14 B. & S.gauge,that, since the passing of thevor- is led down. Telegraphy actinEngland, there (311 A. 3.-Yes.If the coil works contin-penalties involved if any wirelesstl uously, by having the secondary leadstions are erected or worked without short circuited, or if the coil is workeda consent of the Postmaster -General. long time by having the secondary cir- "In conclusion Imay saythatIt cuit "open." very confident that it is onlya ques, A. 4.-Core made of 150-too piecesof time, and nota verylongtlj well annealed iron wires, 6 inches long,before wirelesstelegraphy overgf No. 18 B. & S.Over this core winddistances, possibly round theworld:1 paraffined paper, or, better,use a hardbecome an indispensable aidtoc( rubber tube, over which wind 75-8o merce and civilization." feet Paper read before the Royat I' fik MODERN ELECTRICS 71 ELECTRICAL PATENTS (Continued from Page 63.) Wireless Telegraph Outfit TELEGRAPH -REPEATER. Stephen D. $83,530. Mass. Field, Stockbridge, StephenJ.Heinrich, GREATEST INVENTION OF THE AGE. 883,539. ANNUNCIATOR. Bellevue,FITTING Pa. FOR ELECTRIC CONDUITS. 8$3,549.Allan R. Lakin,New York, N. Y. 883,550. BRUSHAND BRUSH -HOLDER FOR DYNA- MO -ELECTRICMACHINES. Frederick H. Loring, London, England. 433,589. ELECTROLYTIC PRODUCTION OF PURE TIN.Adolphe J. M. Thirot, Bourges, France. 888,594, 883,695.PROCESS OF OBTAINING METALS AND ALLOYS BYREDUCTION.Emilien Viel, Rennes, France. 883,613. LIGHTNING -ARRESTER.Henley V. Bas- tin, Lancaster, Ky. 883,625. CABLE TERMINAL. Frank B. Cook, Chi- cago,Ill. 883,626. ELECTRICAL LINE -PROTECTOR.Frank B. Cook, Chicago,Ill. Not a toy. A scientific, high grade apparatus. Will 483,646. SAFETY DEVICE FOR ELECTRIC POINT work up to one mile. Comprises : Powerful 1 -inch Spark SHIFTING, SIGNALING, LOCKING, AND Coil, Oscillator Balls, Key, Coherer and Decoherer, SWITCHING APPARATUS. LorenzKottmair, 75 Ohm. Relay, Sending and Receiving Wires. etc , etc. Munich, and Rudolf Zwack, Nordendorf, near Augs- Guaranteed in every respect.Price remarkably low. burg, Germany. ELECTROLYTIC PRODUCTION OF CHRO- 883,651.MIC ACID. Max Le Blanc, Karlrube, Germany. CARRIED IN STOCK IN SAN FRANCISCO 883,701. SWITCHING DEVICE. James A. Duffy and Oscar Irwin,Pittsburg,Pa. LEVY ELECTRIC CO. 883,733, 883,724. ELECTRIC TRANSMISSION OF IN- SAN FRANCISCO, CAL. SIZ TELLIGENCE.Isidor Kitse, Philadelphia, Pa. he 883,737. TALKING -SIGN.Lucius R. Paige, Wor- When writing please mention "Modern Electrics." cester, Mass. 883,760. SYSTEM OF DISTRIBUTION.LewisL. Tatum, Norwood, Ohio. 883,777. CLUSTER -LAMP SOCKET. Reuben B. Electrical Novelties? Benjamin, Chicago, Ill. Otto Kraus, New Yes, we have them.Drop us a line if you 583,811. TELEPHONE -SUPPORT. wish to get acquainted with our Geissler th York, N. Y. Tubes, Static Machines, Reflectors, Wireless 883,822. DYNAMO -ELECTRIC MACHINERY. Chas. Goods, etc., etc. A two -cent stamp brings a A. Parsons, Newcastle-upon-Tyne, England. Catalogue that will interest y ou. Write at once 883,823. INSULATOR -SUPPORT.Charles L. Pierce, Jr., Elkhart, Ind. 432 ST. CLAIR STREET 883,846. ELECTRICAL MULTIPLE INFLUENCE OR - - - TOLEDO, 0. CONDENSER MACHINE. HeinrichWommels- J. J. DUCK :er dorf, Charlottenburg, Germany. When writing please mention "ModernElectrics." 883,851. IGNITION MECHANISM FOR INTERNAL- [11, COMBUSTION ENGINES. TheodorusS.Bailey and Frank T. Cable, Quincy, Mass. 883,865. ADVERTISING APPARATUS. Henry Dahn, AN ELECTRIC SUN ALARM. Edgewater,N.J.,and FrederickBecker, New York, N. Y. (Continued from Page 53 ) 883,919. REACTIVE COIL. CharlesP.Steinmetz, Shenectady, N. Y. 883,924. ARC -LAMP ELECTRODE. William S.Wee - As long as no light rays, fall onthe don, Schenectady, N. Y. close con- 883,943. REVERSE -CURRENT CIRCUIT -BREAKER. cell relay, R, is not capable to Charles E. Eveleth, Schenectady, N. Y. tacts, G, as theresistance of C is too 883.944. ELECTRIC LIGHTING.Walter C.Fish, Lynn, Mass. high. 883,956. MOTOR -STARTER. Albert J. Horton, White sunrise Plains, N. Y. In the morning, however, at '883,961. ELECTROMETALLURGICAL PROCESS FOR Lu- enough diffused light reachesthe cell f EXTRACTING COPPER FROM ITS ORES. cien Jumau, Paris, France. to lower itsresistance and if the light 883,964. SIGNALING SYSTEM FOR ELECTRICN. Y. alarm, B, will It RAILWAYS.Harry N. Latey, New York, has grown strong enough 883.992. ELECTRIC TIME -INDICATINGDEVICE. opened, or until William F. Wentz, New York, N. Y. ring until switch, S, is 884.002. CONTROLLER FOR ELECTRIC MOTORS. light ceases falling onthe cell. Thomas E.Barnuin and Henry H.Cutler,Mil- 1 waukee, Wis. This arrangementwill be found to 884,007. TRAIN CONTROL FOR ELECTRICALAC- CUMTJLATOR-LOCOMOTIVES.Otto Bohm, Ber- work quite satisfactoryand is very re- lin, Germany. good ones AlbertS.Gray, liable, if the instruments are *844115cagoE, LIEI1CT. ROLYTIC CELL. and well adjusted. 884,018. INCUBATOR -ALARM.Fremont R. Harris, Kenmare,N.D. It is very seldomthat the alarm will 884.021. APPARATUS FOR MAKING COPPER. faithfully; the writer knows Marcel A. Jullienand Emile L.Dossolle,Leval- not operate 10IS-Perret, France. and that was on a 884,028. ACCUMULATOR -PLATE. MichailMar- of only one instance, Odessa,uA dark,rainy morning when not -247.AUTOMATIC ALARM SYSTEM.John E. very .88.r.l!Pherd, Chicago,Ill. enough diffusedlight reached the cell.. .1_1166. AUTOMATIC ALTERNATING -CURRENT the L.Brown, It is, of course,not necessary that _bi den, APPARATUS.Charles E. Switzerland.!.-.?tNTACT directly on the selenium; '641'°7° SPACETELEGRAPHY. SewallCabot, sun's rays fall diffused lightwill work the cellquite n4,074. ATTACHMENTHMENT FOR TROLLEY -POLE CLAmps.aton.Cuinrtais W. Clark and Charles E. Ying" satisfactory. 72 MODERN ELECTRICS

884,075. ELECTRODEPOSITION OF IRON. She- 884,568. MACHINE FOR MAKINGINCANn.s! rard O. Cowper -Coles, London, England. LAMPS.William R. Burrows,Nela.rk, '.3.076. SPACE TELEGRAPHY.Ernest R. Cram, 884,595. CARRIER SYSTEM.Sam ' Cambridge, Mass. Orange, N. J. 11 Libby, 884.102.ELECTRIC -LAMP SOCKET. Mortimer Nor - 884,607. TELEPHONE FIRE -ALARM den, New York, N.Y. William S. McLewee, Yardley, Pa. Sy 884,106, 884,107, 884,108, 884,109, 884,110. SPACE TELEG- 884,622. ELECTRIC RAILWAY -SIGNAL. RAPHY.John S.Stone, Cambridge, Mass. Stafford, Belcherville, Ira P. Whitaker, -`°I'ke 884,116. ELECTRICAL -IGNITION SPARK -COIL FOR John L. Lopp, Greenwood, Tex. N GAS OR VAPOR ENGINES.Edward Q.Wil- 884,630. TROLLEY POLE AND HEAD.Au, liams, Syracuse, N. Y. Bauer, Philadelphia, Pa. 0.4 ? 884,121. AUTOMATIC ELECTRIC ALARM FOR 884,637. TELEPHONE ATTACHMENT. pc,illiarn BEDS TO BE OCCUPIED BY PATIENTS, SUCH Bythiner, Philadelphia, Pa. AS HOSPITAL -BEDS. FrankApold,Philadel- 884.641. HANGING INSULATOR.Walter G, phia, Pa. New York, N. Y. Cla 884,124. PROCESS FOR THE ELECTROLYSIS OF 584,644, 884.645,884,646. SYSTEM FORELE1,, FLUID SALTS OR COMPOUNDS. Henry S. RAILWAYS. Arthur C. Eastwood, Clevelando 131ackmore, Mount Vernon, N. Y. 884New ELECTROLYTIC CELL. George A. vabript 884,129. ELECTRIC SIGNAL.Arthur J.Cleveland, York, N.,653. Y. 884,664. DEPOLARIZER FOR GALVANIC and Frank S.Brown, Minneapolis, Kans. BAT 884,130. ELECTRIC TIME -SWITCH. James J. TERIES.Ernst W. Jungner, Kneippbaden Coachman, London,England. koping, Sweden. 884,684. TROLLEY HARP AND WHEEL. 884,142.INSULATOR. Ernest J. Foreman, Trinidad, Edwar; Colo. D. Rockwell, Bristol, Conn. 884,731. 884,158.SYSTEM OF AUTOMATIC BLOCK -SIGNAL- ELECTRIC IGNITING DEVICE. Roy ING FOR ELECTRIC RAILWAYS.Winthrop K. Hardy, New York, N. Y. Howe, Buffalo, N. Y. 884,737,884,738. SIGNALING SYSTEM. Edward g 884,170. THIRD -RAIL ELECTRIC -RAILWAY SYS- Kleinschmidt, New York, N. Y. 884,742. ELECTRIC TYPE -WRITER. Jos ,phLcri. TEM.Charles Kozesnik, New York, N. Y. ble, Sennheirm Germany. 884,224. RAILWAY -SIGNAL. John S.Sims, Long - beach, Cal., assignor of one-half to Edward Richard 884,775. ELECTRIC SWITCH.Adolph R. Swobod Millar, Louisville, Ky. Longbeach, Cal. 884,783, 884,784.SIGNAL SYSTEM FOR RAILWA 884,235. RECEIVER FOR TELEPHONES. Louis Maximillian G. Voigtlander, Harrison, Oldo. Steinberger, New York, N. Y. 884,825. AUTOMATIC ELECTRIC CROSSING -GA 884,247. COIN -CONTROLLED APPAR.ATUS.David Frank G. Layher, Jackson, Mich. Wedgewood, Peterboro, Ontario, Canada. 884,831. ALTERNATING -CURRENT GENERA 884,264.STORAGE BATTERY. George A. Carpenter, Carl A. Lohr, Wilkinsburg, Pa. New York, N. Y., administratrix of Hiram Henry 884,843. MONEY -DRAWER ALARM. Sillus Carpenter. Costa Newman, Tellico, Tenn. 884,271. ELECTRIC -LIGHT SOCKET. Franz Frank- 884,919,884,920. PROCESS FOR MAKING NIT ofski, North Braddock, Pa. GEN OXIDS FROM AIR. August Grau and F 884,296. ELECTRIC CURLING -IRON. ClaraA. Russ, Vienna, Austria-Hungary. Rickards,Portland,Ore. 884,930. ELECTRODE FOR REVERSIBLE GAL 883,312. ELECTRICAL CONNECTOR. JamesL. VANIC BATTERIES.Ernst W. Jungner, KneiPP Carnall, New York, N. Y. baden, Norrkoping, Sweden. 884,343. ELECTRIC WATER -HEATER.Herbert N. 884,969. THERMOSTATIC CIRCUIT -CLOSER. J Roche, San Francisco, Cal. 0. Woods, Riverside, Wash. 884,353. ELECTRIC SWITCH.Herbert H. Berry, 884,973. AUTOMATIC INDICATOR OR THERM Enfield, England. SCOPIC SIGNAL FOR HEATED TOOLS A. 884,358. ELECTRICALLY -SYNCHRONIZED TIME- VESSELS.James I.Ayer, Cambridge, Mass. MEASUREING INSTRUMENT. Bahne Bonniksen, 884,986,884,987,884,988. WIRELESS TELEGRAP Coventry, and Frederick A. Chandler, Leamington, Guglielmo Marconi, London, England. England. 885,000,885,001,885,002. SWITCH FOR. TROLLS 884,367. ELECTRICAL WATER -HEATER.Edward Ewan Cameron, Brooklyn, N. Y. J. Condon, New York, N. Y. 884,381. TELEGRAPH -TRANSMITTER. Mark S. Haling, Weaver, Minn. TESTING A MODERN ELECTRIC 884,397. OVERHEAD TROLLEY. Allen P. Lord and Nathaniel Wilkins, Bradford, Pa. LOCOMOTIVE. 884,424. ELECTRICAL FLUID -HEATER.Mark T. (Continued from Page 42 ) Seymour, Bemus Point, and Alton W. Ball, Stowe, N. Y. In this way we pass ,over thatpart 0 884,441. COIN -CONTROLLED APPARATUS.John A. Weser, New York, N. Y. the test track containing severalcurvy 884,456. INSULATING COMPOUND. Nathan Booth. aboti Alexandria, Ind. and a slight up grade, which ends 884,458. ELECTRIC -CURRENT REGULATOR.Ar- one mile west of the sub -station. T.11 thur W. Brice, Rochester, N. Y. ending 111 884,466. SWITCH -BOX.Thomas J.Cleland, Chica- we enter a straight stretch, go,Ill. long, well-balasted curve, equal toaboti 884,470. COIN -COLLECTOR. Edward B. Craft, Chi- cago,Ill. 70 degrees of the circumferenceof 884,500. TELEPHONE DESK -STAND. Anton M. cl°5 Knudsen, Chicago,Ill. circle, and on the inside' of which, 884,511. SELF-STARTER Walter 0. Lum, Schenec- ba tady, N. Y. to the track, is the sub -station and 884,514. AUTOMATIC ELECTRIC SWITCH. Andrew and just beyond the crossing.Direct H. Miller, Chesaning, Mich. 884,516.MACHINE FOR PRINTING FROM FILMS upon leaving the(sharper curves OR PLATES.Clyde G. Morgan, Mount Vernon, motorman giveshisgearlessmach° Mo. 884,517. CONDUIT ELECTRIC RAILWAY.Lewis (the axles of the drivers are thesil'Ith W. Musick, Crescent City, Cal. 884.519. FUSE -HOLDER FOR ELECTRIC -CIRCUIT of the motors around which are CONDUCTORS. Patrick McDonald, Rochester, armatures) the entire 666 volts,and N. Y. 884,540.. ELECTRIC HEATER. ElihuThomson, immediately experienceanincrease Swampscott, Mass. speed.This continues untilitreac.,', 884,541. SYSTEM OF CONTROL FOR ELECTRIC strl"' MOTORS.Leonard A. Thrill. Lynn, Mass. about 74 mires per hour, when it 884,546. TROLLEY -WHEEL.Frederick G.Walker, Cleveland, Ohio. the curve, reels gently to one side 3 884,555. REGULATION OF DYNAMO -ELECTRIC settles itself in that position.The MACHINES. Charles E. Barry. Schenectady, N.Y. 884.563. PROCESS OF FUSING MATERIALS. Geo. torman pulls the chord of his great F. Brindley, Niagara Fans, Ontario, Canada. pressed air whistle for four long,toti (Continued on Page 74.) MODERN ELECTRICS 73 ARC LIGHTS IN RAILROA D SPEAKING DEPOTS.. CLASSIFIED ADVERTISEMENTS. The speakingarc lamp has atlast Advertisements in this column 2 practical use in some of the large found cents a word, no display of any Germantowns. kind.Payable in advance, stamps Most Americans are now soused to not accepted.Count 7 words ,per the bellowing,howling individual in our line. Minimum, 2lines.Heavy largerailroad stations, who pretends tell- face type 4 cents a word.,Mini- lig us whatthe destination of the next mum, 3 lines.. rain is, thatthey do not mind his un- sthetic roar any more.There are even ELECTRICAL APPR A TUS. ome peoplewho boast that they can un- STUDY ELECTRICITY AT HOME --A complete electrical course at home, containing 30 -page detail. lerstand every "word" which these train book,220 -pagetext -book,200experimentsand nnouncers trumpet out,but the poor over 100 pieces of apparatus.Price, complete, only $5.60. Catalogue M.E.S."explains thisand strangerwould much ratherheara other remarkable offers.Thomas M. St. John, 848 dozenSiouxbraves howltheirwar Ninth Ave., New York. R-11 INTERESTED IN THE STUDY OP whoops than try to make' out where the ELECTRICITY? Limited offer. One Set (No.1) next train stops first. Comprising 10 Leading Instruments, $8.50. Junior set (No. 21 7 instruments. *4.50. Send Apparently the Germans were the first2e. stamp for circulars, Palmer Electrical Instrument Co.. 38th Street, z above Market, .torealizetheimportanceofhavingPhiladelphia, Pa. an efficient way to call out trains, and ELECTRICAL GOODS at half price.Send for to this effect they first equipped some of catalogue.Harold Decker, La Porte, Ind. Berlin's large depots with extra strong BOYS, BUILD TELEPHONE LINES. Special phonograph announcers. bargainsinsecond-hand andremodeledinstru- ments.All supplies at wholesale.Send 5 cents for big catalog and sample of wonderful burning wire.Meyers Electrical House, Evansville. Wis. WIRELESS TELEGRAPHY - New detector, t-\ guaranteed to receive messages from points hundreds of miles away.Simple and easily adlusrea. Will not burn out nor lose its sensitiveness. Price, 50 cents, prepaid..(No stamps.)P. 0. Box 448; Jan New Orleans, La. ELECTRICAL BOOKS, BLUEPRINTS, ETC. WIRELESS TELEGRAPHY.-How to make a practical outfit cheaply.Complete details and diagrams 25e. post paid. Edwin Arnold, 102 Gelston St., Buffalo, N. Y. FOUR TYPES of High Tension Induction Coils for Tuned Circuit Wireless Telegraphy.Set of 12 ,-._,.... -*A.: drawings, giving full data;price,$1.00. W. C. Getz, 645 N. Fulton Ave., Baltimore, Md. It was found out soon though that HOW TO MAKE ai Chemical Rectifier.Book, 25 these phonographs could be understood oents. Taylor Electrical Mfg.Co.,207 SaySt., ,onlyin certain parts of the waiting - Albany, N. Y. WIRELESS TELEGRAPHY-How toconstruct rooms; the acoustic properties of the and operate a wireless station at home.No expe- large halls didnot seem to be just what rience necessary.Price, 50 cents. (No stamps.) they ought to be and the phonographs P. 0. Box 448 New Orleans, La. ELECTRIC MOTOR CONSTRUCTION FOR AM- were sent to thescrap heap. ATEURS, by C.D. Parkhurst, 75 cents.Walter Nexta bright "elektriker" hit upon D. Dunkle, 356 W. Chestnut St.,Washington, Pa. the ideato use 4-6 speaking arc lights, FOR SALE. all of them These FOUR -INCH DEVINE WATER MOTOR,$3.50; connected in series. 12 Watt dynamo, $3.50; completeoutfit with lights, ilampsare scattered over the waiting - diagrams, etc., $7.00.Special motor, new style. 6 $2.00. Any stylelight, rooms andplaced so that they give the Watt, drum Z.,armature, 131 Norwood Ave., Buffalo, N. Y. maximum 36c.C. D. effect. DEVINE WATER MOTORS, $7.00; 85 lercent An operatortalks in a specially de- efficiency ;6 volts, 6 ampere's, K. & D. generators, lresigned modeled from large typegenerator, $6.00;corn- transmitter in the operating room pletk plant. $13.00; Just thething for wireless out- and it is electric lighting a tItiexperiaaert:s.C. W. A., not necessary at all to exert fits. Buffalo, N. Y. the voiceto obtain best results. 316 Woodward Ave., FOR SALE-A i/2 -hp.Electric Motor in good The advantageof the system is that condition, will sell for$15.00.J. E. Handley, Rock the talking City Falls, N .Y. the ,r00in is done in different parts of and while notas loud as the FOR SALE-"Fisher"storage battery charger. slowing- with automatic cut-out;slightly used; perfect con- gof a single hoarseman, the costs $25.00, new ;will st-11 for$15.00. dition; Cleburne, Kan. e is heardplainly everywhere. Write.Victor E. Hawkinson, MODERNELECTRICS TESTING A MODERN PLR ACCURATE L000110TIVE.

COMPACT (Continued from Page 72. INEXPENSIVEpiercing blasts, grasps hiscurrent Send for completebrake levers, and we rush upon thei catalog of portablesub -station, which is situatedat the and switchboardend of the curve and partially hidden Voltmeters, Amme-trees. We are now half -way around-. tersand Volt -Am- meters. move at a terrific speed when it sud New Round Switchboard, ly appears almost in our verypath. Volt or Ammeter, 5 inches in diameter. L. M. PIGNOLETon it comes,increasing in sizeuntil l% inches deep. finally dash up toit and just mi Bestinstrument onthe 82Cortlandt Street market. passing barely to one side. When PRICE, $8.00 UP New York abreast of it there is a deafening When writing please mention"Modern Electrics." of the whistle and we rush past on far side, and, looking back, we Electric PowerMotorpedestrians at the crossing holding their hats and one another, while to Sample Prepaid we rapidly growsmaller in the di for 35c. We have now entered the tw Agents Wanted " straightaway with no crossing, cha grade or curve within that distance EMPIRE ELECTRIC the whole six miles of track the mile, half, and quarter -mile posts WORKS one, two and threeblack hands on 1063 BRIDGEPORT, CONN. respectively:These we pass in q When writing please mention "Modern Electrics." succession after leavingWyatt's, when within a half -mile ofthe WATCH THIS SPACEwhere the power must be shutoff If you want GOODcouple of the men time ourflight goods, GOOD servicestop watches.Eleven and three -t and GOOD attentionseconds is the verdict.We know paid to you, write us.this is for a whole quarterof a Ourtrade mark showsand with it comes the realizationthat "what's what." A generous catalog,are covering distance atthe rateof : showing a line of themiles per hour.But howeasily, best suppliesinthis past country will be mailedthink.The objects outside have to you promptly onuswithincrediblerapidity,but A Square Deal receipt of 17 cents forthought ofsuch speedwould very PromptDeliveries postage. when we would think of the of .all M.E F letcher-Stanly Co. sway and the entire abserice 36 FRANKFORT ST., NEW YORK ward lurching. Now we realize that thetrain 0 When writing please mention "Modern Electrics." steam tracks, which, weovertook left behind us in our madrush, BELL TRUST SMASHED 601 Now is the time to buy cheap. really a limited making up lost Never again will you have such a that chance. ' Electra " Iron Box it now flies past us at a speed Bell, 2% inch Gong, sold three declar weeks ago for 35c everywhere, yesterday we would have being"fast !"Ourshortbut NOW 18c journey is over now and asthe D This ridiculous price only good to ai up to May 20th.Order today. are applied we come quietly Our supply is limited. First come, an;, first served still, and take a long breath To OUR FRIENDS :-If you are realize what we have experienced. wise, lay in a supply now.In June the price will go up.You make 50% profit on each bell.. Remember, each bell guaran- The "Mauretania" has fourdyrianu's teed or money back. of which is capable to give 3,260 arnPi.r.0 ElectroImporting Co., 86-Z West Broadway, N. Y.City tit voltst5te a speedare of1,200 usedreVItc,loti.i(1:51 NOTE NEW ADDRESS Fiftyatlargefansare to cool these dynamos which never When writing please mention "ModernElectrics." the entire length of a trip. MODERN ELECTRICS

SPECIAL30 DAY OFFER $5.00 BUYS IT To introduce our line of Home Companion Tool Sets among the rea dens of "M oder n Electrics" we are offering for a limited time only our 1 NO. 110 SET FOR $5.00 EXPRESSAGE PAID. These Tool Sets of ours comprise tools of our own manufacture, whose quality is well known, put up in handsome hardwood cases. A complete list of the tools in each of these assortments will be found in our No. 8 Catalog which we will send free to any address.

No.700 $3.50 No. 711 $8.00. No. 112 $10.00 No. 713 $12.00 COODELL-PRATT COMPANY, 86 CREENFIELD, MASS.,U. S. A.

When writing please mention "Modern Electrics." ...THE ... 'SOMETHING NEW "Electro" Static (Wimshurst) Machine Our Canoe and Bicycle Search r Guaranteed to generate in any kind of weather, Light is a wonder. no matter, foggy or rainy The first machine ever Throws a power- constructed which can truthfully claim this. We ful beam of brit- absolutely guarantee a fat, powerful 3 -in. spark from liant whitelight our new machine.It is used successfully to operate for a distance of Geissler and X -Ray tubes, charging the biggest Ley- TOO feet.Fits any den jars,firing bicycle, and can be powder, working attached to any vehicle. wireless sets for The search light is mova- shortdistances. ble to throw the beam in any direction wanted. Lamp is adjusta- raising a ble and finely nickelplated.Works with ordinary dry cells or nerson's ;mall storage battery.Conies withTantalumlamp, using hair. etc. ampere.When ordering state voltage lamp is to be used on. Anybody PRICE, COriPLIETE, St SO BY MAIL n t erected Headquarters for scientific electrical goods. New apparatus made in electric- to order. Inventor's materials.Can send pamphlet ofany ity owes it electrical apparatus on receipt of 2 cent stamp. to himself to pos- Uwe havn't-ot it, it ls'nt made. sess one of these wonderful ma- Manufacturers' and Inventors' Electric Co. chines which can be used to per- 821'2 NASSAU STREET, NEW YORK form thousands of interesting experiments t cur When writing please mention "Modern Electrics." cutshowsthe L machine plainly. It comprises two A Sensational Novelty. 8 -in. glass crys- Will Last a Lifetime tal plates revolv- anding indischarging oPnosite directions,two adjustable oscillator THE IMPROVED FLAMING onei iron clamprods and balls D, collectors H and POCKET LIGHTER. x14 in. Weightto fasten body to table.Size over all boxed 8 lbs.Nothing to wear out. Patented July 9, 1907, and Sept. lo, 1907 b.atteries.no trouble. ply turn the crank, the machinedoes the rest.Price, complete boxed, Infringers cautioned. -47,tend haven't got our 100 page catalogue Fvery smoker wants it. Will light in windy weather. 2cc stamp for it; contains 100 experiments. p. Better than matches. A little deodorized wood alcohol once in a while does the trick.Nothing to ,,,,ear Electro out.Sample milled upon receipt of 55c.Special Importing Co. prices to dealers in dozen or gross lots.If you wish 86z WestBroadway, York to make l ig money this summer write at once to "Everything for theExperimeNn7ewr" The Auto Igniter Co., 1947! Irdway, N. Y. City ilf? writing rn.ntion 'M. 'Iris.''s.' ' W hen writing please mention "Modern Electrics." "Modern Electrics"guarantees the reliabilityof its advertisers. Send for itSend for it Send for itSend Send for itSend for it for Send for itSend for itSend for it Send psi' Send for itSend for it for, Send for itSend for it Send for it Send Send for itSend for it for I. Send for itSend for itSend for it Send vol. Send for itSend for it fori,' Send for itSend for itSend for it Send Send for itSend for it fori, Send for it Send Send for it Send forit for Send for it Send Send for it Send forit for: STARRETT Send for it Send Send for it Send forit fori: Send for it Send Send for it Send forit TOOLS fork Send for it Send for it Sendfor it Sendfori, Send for it Send for it Sendfor it Sendfor Send for it Send for it Sendfer it Sendfor Send for it Send for it Sendfor it Send Send for it Send for it Sendfor it Sendfor: Send for it Send for it Sendfor it Sendfor; Send for it Send for it Sendfor it Sendfor: Publish( THEL.S.STARRETTGO. Send for it Send for it ATHOL,NASS. Sendfor it Sendfori Send for it Send for it U.S.A. Sendfor it Sendfor: NEWYORK ,Cii1CAGOIONDON Send for it Send for it Sendfor it Sendfori; Send for it Send for itSend for itSend forit Sendfor it Sendfor': Send for it Send for itSend for itSend forit Sendfor it Sendfor: Send for it Send for itSend for itSend forit SendforitSendfori Send for it Send for itSend for itSend forit Sendfor it Sendfori. Send for it Send for itSend for itSend forit Sendfor it Sendfor When writing please mention "Modern ElectrIcs."

There are XX chapters in all XIX carrying you from the funde mental pH -doles of electricity on through the various Manche A School Within Itselfto a point where the careful student comprehends thecomple, designing, care and operation of a dynamo or motor and I chapter on electric automobiles, outlining their construction, tamed operation, and all about storage batteries and how to handle them.Each subject is carefully written and to the point. After ! student studies a subject, he is questioned onlie subject in such a manner as to bring clearlyto M mind the points he needs to know regarding so,Vlie A in back of book will enable to learn the meaning of any electrical word.terrob, in as well ashundreds !' others in common use. All required tablesnem' sary in the st,dy CHAP -TER TABLE OF SUBJECTS: IWiringthairsebinooitk., EmleacctirieustiBantatteries. ElectricPlatlot Ali IV The Magnetic Circuit V Magnetic Traction VI Magnetic Leakage VII Energy in Electric Circuit 31sr VIII Calculation of Size of Wire for PRACT1cA_L Coi IX Calculation)of E. 111. F's inElectra ELECTriCIT X Counter E. M. F. PUBLISHED By RA tett la is ArmatureneReactionCurrentsy CLEVELAND ARMATUREWORKS Motors n X I V Winding of Dynamos and XV Proper Method ofConnecting of namos andMotors --SelfEl" and others 60 $2.00 PER COPY-FOURTH EDITION -- C .PIES SOLD. if ,1 The offer we make of refunding money $ tfr: is not satisfactory upon examinationIt'1, d,' USUAL ONE in connection with the s' YLP book. But we have no fear of itsreturn ArtIr decision will be what thousands of uc'tki.odit: would not buy it if it coad print testimonials hundreds.It is best to order and be r''' mWeriets.could CLEVELAND ARMATURE " '''. Ili' 102:LEEI.AIVIE " AMERICA'S GREATEST REPAIR WeRS, ARMATURES AND FIELDS WOUND. COMMUTATOR When Writing pleasemention "Modern Fileetries."