Thecurseofthisworkandofallthatsucceededitforascoreofyearswasthenecessityofdependinguponchemicalbatteriesforcurrent，themachineusuallybeingself-containedandhaulingthebatteriesalongwithitself，asinthecaseofthefamousPageexperimentsinApril，1851，whenaspeedofnineteenmilesanhourwasattainedonthelineoftheWashington&Baltimoreroad。Tothisunfruitfulperiodbelonged，however，thecrudeideaoftakingthecurrentfromastationarysourceofpowerbymeansofanoverheadcontact，whichhasfounditspracticalevolutioninthemodernubiquitoustrolley；
althoughthepatentforthis，basedonhiscaveatof1879，wasgrantedseveralyearslaterthanthattoStephenD。Field，forthecombinationofanelectricmotoroperatedbymeansofacurrentfromastationarydynamoorsourceofelectricityconductedthroughtherails。Asamatteroffact，in1856andagainin1875，GeorgeF。Green，ajobbingmachinist，ofKalamazoo，Michigan，builtsmallcarsandtrackstowhichcurrentwasfedfromadistantbattery，enoughenergybeingutilizedtohaulonehundredpoundsoffreightoronepassengerupanddowna“road“twohundredfeetlong。Alltheworkpriortothedevelopmentofthedynamoasasourceofcurrentwassporadicandspasmodic，andcannotbesaidtohaveleftanytraceontheart，thoughitofferedmanysuggestionsastooperativemethods。
Thecloseofthesamedecadeofthenineteenthcenturythatsawtheelectriclightbroughttoperfection，sawalsotherealizationinpracticeofallthehopesoffiftyyearsastoelectrictraction。Bothutilizationsdependeduponthesupplyofcurrentnowcheaplyobtainablefromthedynamo。Theseartswereindeedtwins，feedingatinexhaustiblebreasts。
In1879，attheBerlinExhibition，thedistinguishedfirmofSiemens，towhoseingenuityandenterpriseelectricaldevelopmentowessomuch，installedaroadaboutone-thirdofamileinlength，overwhichthelocomotivehauledatrainofthreesmallcarsataspeedofabouteightmilesanhour，carryingsometwentypersonseverytrip。Currentwasfedfromadynamotothemotorthroughacentralthirdrail，thetwoouterrailsbeingjoinedtogetherasthenegativeorreturncircuit。Primitivebutessentiallysuccessful，thislittleroadmadeaprofoundimpressiononthemindsofmanyinventorsandengineers，andmarkedtherealbeginningofthegreatnewera，whichhasalreadyseenelectricityappliedtotheoperationofmainlinesoftrunkrailways。Butitisnottobesupposedthatonthepartofthepublictherewasanygreatamountoffaiththendiscernible；andforsomeyearsthepioneershadgreatdifficulty，especiallyinthiscountry，inraisingmoneyfortheirearlymodestexperiments。OfthegeneralconditionsatthismomentFrankJ。SpraguesaysinanarticleintheCenturyMagazineofJuly，1905，onthecreationofthenewart：“Edisonwasperhapsnearerthevergeofgreatelectric-railwaypossibilitiesthananyotherAmerican。Inthefaceofmuchadversecriticismhehaddevelopedtheessentialsofthelow-internal-
resistancedynamowithhigh-resistancefield，andmanyoftheessentialfeaturesofmultiple-arcdistribution，andin1880hebuiltasmallroadathislaboratoryatMenloPark。“
OnMay13thoftheyearnamedthisinterestingroadwentintooperationastheresultofhardandhurriedworkofpreparationduringthespringmonths。
Thefirsttrackwasaboutathirdofamileinlength，startingfromtheshops，followingacountryroad，passingaroundahillattherearandcurvinghome，inthegeneralformoftheletter“U。“Therailswereverylight。CharlesT。Hughes，whowentwithEdisonin1879，andwasinchargeofmuchofthework，statesthattheywere“second“street-carrails，insulatedwithtarcanvaspaperandthingsofthatsort——
“asphalt。“Theywerespikeddownonordinarysleeperslaiduponthenaturalgrade，andthegaugewasaboutthreefeetsixinches。Atonepointthegradedroppedsomesixtyfeetinadistanceofthreehundred，andthecurveswereofrecklesslyshortradius。Thedynamossupplyingcurrenttotheroadwereoriginallytwoofthestandardsize“Z“machinesthenbeingmadeatthelaboratory，popularlyknownthroughouttheEdisonranksas“LongwaistedMaryAnns，“andthecircuitsfromthesewerecarriedouttotherailsbyundergroundconductors。Theywerenotlarge——abouttwelvehorse-powereach——generatingseventy-fiveamperesofcurrentatonehundredandtenvolts，sothatnotquitetwenty-fivehorse-powerofelectricalenergywasavailableforpropulsion。
Thelocomotivebuiltwhiletheroadbedwasgettingreadywasafour-wheeledirontruck，anordinaryflatdump-caraboutsixfeetlongandfourfeetwide，uponwhichwasmounteda“Z“dynamousedasamotor，sothatithadacapacityofabouttwelvehorsepower。Thismachinewaslaidonitsside，withthearmatureendcomingoutatthefrontofthelocomotive，andthemotivepowerwasappliedtothedriving-axlebyacumbersomeseriesoffrictionpulleys。
Eachwheelofthelocomotivehadametalrimandacentrewebofwoodorpapier-mache，andthecurrentpickedupbyonesetofwheelswascarriedthroughcontactbrushesandabrasshubtothemotor；thecircuitbacktothetrack，orotherrail，beingclosedthroughtheotherwheelsinasimilarmanner。Themotorhaditsfield-magnetcircuitinpermanentconnectionasashuntacrosstherails，protectedbyacrudebarecopper-wiresafety-catch。
Aswitchinthearmaturecircuitenabledthemotormantoreversethedirectionoftravelbyreversingthecurrentflowthroughthearmaturecoils。
ThingswentfairlywellforatimeonthatmemorableThursdayafternoon，whenallthelaboratoryforcemadehighholidayandscrambledforfootholdonthelocomotiveforatrip；butthefrictiongearingwasnotequaltothesuddenstrainputuponitduringonerunandwenttopieces。Someyearslater，also，DaftagaintriedfrictiongearinhishistoricalexperimentsontheManhattanElevatedroad，buttheresultswereattendedwithnogreatersuccess。ThenextresortofEdisonwastobelts，thearmatureshaftingbeltedtoacountershaftonthelocomotiveframe，andthecountershaftbeltedtoapulleyonthecar-
axle。Theleverwhichthrewtheformerfrictiongearintoadjustmentwasmadetooperateanidlerpulleyfortighteningtheaxle-belt。Whenthemotorwasstarted，thearmaturewasbroughtuptofullrevolutionandthenthebeltwastightenedonthecar-
axle，compellingmotionofthelocomotive。Butthebeltswereliabletoslipagreatdealintheprocess，andthechafingofthebeltscharredthembadly。Ifthatdidnothappen，andifthebeltwasmadetautsuddenly，thearmatureburnedout——whichitdidwithdisconcertingfrequency。Thenextstepwastouseanumberofresistance-boxesinserieswiththearmature，sothatthelocomotivecouldstartwiththoseincircuit，andthenthemotormancouldbringituptospeedgraduallybycuttingoneboxoutaftertheother。Tostopthelocomotive，thearmaturecircuitwasopenedbythemainswitch，stoppingtheflowofcurrent，andthenbrakeswereappliedbylonglevers。
Mattersgenerallyandthemotorsinparticularwentmuchbetter，evenifthelocomotivewassofreelyfestoonedwithresistance-boxesallofperceptibleweightandoccupyingmuchofthelimitedspace。
Thesedetailsshowforciblyandtypicallythepainfulstepsofadvancethateveryinventorinthisnewfieldhadtomakeintheefforttoreachnotalonecommercialpracticability，butmechanicalfeasibility。
Itwasallempiricalenough；butthatwastheonlywayopeneventothehighesttalent。
Smugglerslandinglacesandsilkshavebeenknowntowindthemaroundtheirbodies，asbeinglessostentatiousthancarryingtheminatrunk。Edisonthoughthisresistance-boxesanequallysuperfluousdisplay，andthereforeingeniouslywoundsomecopperresistancewirearoundoneofthelegsofthemotorfieldmagnet，whereitwasoutoftheway，servedasausefulextrafieldcoilinstartingupthemotor，anddismissedmostoftheboxesbacktothelaboratory；
afewbeingretainedundertheseatforchanceemergencies。
Liketheboxes，thiscoilwasinserieswiththearmature，andsubjecttoplugginginandoutatwillbythemotorman。Thusequipped，thelocomotivewasfoundquitesatisfactory，andlongdidyeomanservice。Itwasgiventhreecarstopull，oneanopenawning-carwithtwoparkbenchesplacedbacktoback；oneaflatfreight-car，andonebox-cardubbedthe“Pullman，“withwhichEdisonillustratedasystemofelectricbraking。Althoughworkhadbeenbegunsoearlyintheyear，andtheroadhadbeenoperatingsinceMay，itwasnotuntilJulythatEdisonexecutedanyapplicationforpatentsonhis“electromagneticrailwayengine，“orhisingeniousbrakingsystem。Everyinventorknowshowlargelyhisfateliesinthehandsofacompetentandalertpatentattorney，inboththepreparationandtheprosecutionofhiscase；andMr。SpragueisjustifiedinobservinginhisCenturyarticle：““Thepaucityofcontrollingclaimsobtainedintheseearlypatentsisremarkable。“
ItisnotoriousthatEdisondidnotthenenjoytheskilfulaidinsafeguardinghisideasthathecommandedlater。
Thedailynewspapersandtechnicaljournalslostnotimeinbringingtheroadtopublicattention，andtheNewYorkHeraldofJune25thwasswifttosuggestthatherewasthelocomotivethatwouldbe“mostpleasingtotheaverageNewYorker，whoseheadhasachedwithnoise，whoseeyeshavebeenfilledwithdust，orwhoseclotheshavebeenruinedwithoil。“Acoupleofdayslater，theDailyGraphicillustratedanddescribedtheroadandpublishedasketchofaone-hundred-horse-powerelectriclocomotivefortheuseofthePennsylvaniaRailroadbetweenPerthAmboyandRahway。Visitors，ofcourse，werenumerous，includingmanycurious，scepticalrailroadmanagers，fewifanyofwhomexceptVillardcouldseetheslightestuseforthenewmotivepower。Thereis，perhaps，someexcuseforsuchindifference。Nomenintheworldhavemorenewinventionsbroughttothemthanrailroadmanagers，andthiswastherankestkindofnovelty。Itwasnot，indeed，untilayearlater，inMay，1881，thatthefirstregularroadcollectingfareswasputinoperation——alittlestretchofoneandahalfmilesfromBerlintoLichterfelde，withoneminiaturemotorcar。
Edisonwasinrealitydoingsomeheavyelectric-
railwayengineering，hisapparatusfullofideas，suggestions，prophecies；buttotheoperatorsoflongtrunklinesitmusthaveseemedutterlyinsignificantand“excellentfooling。“
Speakingofthissituation，Mr。Edisonsays：“OnedayFrankThomson，thePresidentofthePennsylvaniaRailroad，cameouttoseetheelectriclightandtheelectricrailwayinoperation。Thelatterwasthenaboutamilelong。Herodeonit。AtthattimeI
wasgettingoutplanstomakeanelectriclocomotiveofthreehundredhorse-powerwithsix-footdrivers，withtheideaofshowingpeoplethattheycoulddispensewiththeirsteamlocomotives。Mr。Thomsonmadetheobjectionthatitwasimpracticable，andthatitwouldbeimpossibletosupplantsteam。Hisgreatexperienceandstandingthrewawetblanketonmyhopes。ButIthoughthemightperhapsbemistaken，astherehadbeenmanysuchinstancesonrecord。Icontinuedtoworkontheplans，andaboutthreeyearslaterIstartedtobuildthelocomotiveattheworksatGoerckStreet，andhaditaboutfinishedwhenIwasswitchedoffonsomeotherwork。
OneofthereasonswhyIfelttheelectricrailwaytobeeminentlypracticalwasthatHenryVillard，thePresidentoftheNorthernPacific，saidthatoneofthegreatestthingsthatcouldbedonewouldbetobuildright-anglefeedersintothewheat-fieldsofDakotaandbringinthewheattothemainlines，asthefarmersthenhadtodrawitfromfortytoeightymiles。Therewasapointwhereitwouldnotpaytoraiseitatall；andlargeareasofthecountrywerethusofnovalue。Iconceivedtheideaofbuildingaverylightrailroadofnarrowgauge，andhadgotallthedataastothewindsontheplains，andfoundthatitwouldbepossiblewithverylargewindmillstosupplyenoughpowertodrivethosewheattrains。“
AmongotherswhovisitedthelittleroadatthisjuncturewerepersonsinterestedintheManhattanElevatedsystemofNewYork，onwhichexperimentswererepeatedlytriedlater，butwhichwasnotdestinedtoadoptamethodsoobviouslywellsuitedtoalltheconditionsuntilaftermanysuccessfuldemonstrationshadbeenmadeonelevatedroadselsewhere。
ItmustbeadmittedthatMr。Edisonwasnotveryprofoundlyimpressedwiththedesireentertainedinthatquartertoutilizeanyimprovement，forheremarks：“WhentheElevatedRailroadinNewYork，upSixthAvenue，wasstartedtherewasagreatclamoraboutthenoise，andinjunctionswerethreatened。
Themanagementengagedmetomakeareportonthecauseofthenoise。Iconstructedaninstrumentthatwouldrecordthesound，andsetouttomakeapreliminaryreport，butIfoundthattheyneverintendedtodoanythingbutletthepeoplecomplain。“
Itwasupontheco-operationofVillardthatEdisonfellback，andanagreementwasenteredintobetweenthemonSeptember14，1881，whichprovidedthatthelatterwould“buildtwoandahalfmilesofelectricrailwayatMenloPark，equippedwiththreecars，twolocomotives，oneforfreight，andoneforpassengers，capacityoflattersixtymilesanhour。
Capacityfreightengine，tentonsnetfreight；costofhandlingatonoffreightpermileperhorse-powertobelessthanordinarylocomotive……Ifexperimentsaresuccessful，Villardtopayactualoutlayinexperiments，andtotreatwiththeLightCompanyfortheinstallationofatleastfiftymilesofelectricrailroadinthewheatregions。“Mr。EdisonisauthorityforthestatementthatMr。Villardadvancedbetween$35，000and$40，000，andthattheworkdonewasverysatisfactory；butitdidnotendatthattimeinanypracticalresults，astheNorthernPacificwentintothehandsofareceiver，andMr。Villard\'sabilitytohelpwashopelesslycrippled。ThedirectorsoftheEdisonElectricLightCompanycouldnotbeinducedtohaveanythingtodowiththeelectricrailway，andMr。InsullstatesthatthemoneyadvancedwastreatedbyMr。EdisonasapersonalloanandrepaidtoMr。Villard，forwhomhehadahighadmirationandastrongfeelingofattachment。Mr。Insullsays：
“AmongthefinancialmenwhoseclosepersonalfriendshipEdisonenjoyed，IwouldmentionHenryVillard，who，Ithink，hadahigherappreciationofthepossibilitiesoftheEdisonsystemthanprobablyanyothermanofhistimeinWallStreet。HedroppedoutofthebusinessatthetimeoftheconsolidationoftheThomson-HoustonCompanywiththeEdisonGeneralElectricCompany；butfromtheearliestdaysofthebusiness，whenitwasinitsexperimentalperiod，whentheEdisonlightandpowersystemwasbutanidea，downtothedayofhisdeath，HenryVillardcontinuedastrongsupporternotonlywithhisinfluence，butwithhismoney。HewasthefirstcapitalisttobackindividuallyEdison\'sexperimentsinelectricrailways。“
InspeakingofhisrelationshipswithMr。Villardatthistime，Edisonsays：“WhenVillardwasallbrokendown，andinastuporcausedbyhisdisastersinconnectionwiththeNorthernPacific，Mrs。Villardsentformetocomeandcheerhimup。Itwasverydifficulttorousehimfromhisdespairandapathy，butItalkedabouttheelectriclighttohim，anditsdevelopment，andtoldhimthatitwouldhelphimwinitallbackandputhiminhisformerposition。Villardmadehisgreatrally；hemademoneyoutoftheelectriclight；andhegotbackcontroloftheNorthernPacific。Undernocircumstancescanahustlerbekeptdown。Ifheisonlysquare，heisboundtogetbackonhisfeet。Villardhasoftenbeenblamedandseverelycriticised，buthewasnottheonlyonetoblame。Hisengineershadspent$20，000，000toomuchinbuildingtheroad，anditwasnothisfaultifhefoundhimselfshortofmoney，andatthattimeunabletoraiseanymore。“
Villardmaintainedhisintelligentinterestinelectric-
railwaydevelopment，withregardtowhichEdisonremarks：“AtonetimeMr。VillardgottheideathathewouldrunthemountaindivisionoftheNorthernPacificRailroadbyelectricity。Heaskedmeifitcouldbedone。Isaid：`Certainly，itistooeasyformetoundertake；letsomeoneelsedoit。\'Hesaid：
`Iwantyoutotackletheproblem，\'andheinsistedonit。SoIgotupaschemeofathirdrailandshoeanderecteditinmyyardhereinOrange。WhenI
gotitallready，hehadallhisdivisionengineerscomeontoNewYork，andtheycameoverhere。Ishowedthemmyplans，andtheunanimousdecisionoftheengineerswasthatitwasabsolutelyandutterlyimpracticable。ThatsystemisontheNewYorkCentralnow，andwasalsousedontheNewHavenroadinitsfirstworkwithelectricity。“
AtthispointitmaybewelltocitesomeotherstatementsofEdisonastokindredwork，withwhichhehasnotusuallybeenassociatedinthepublicmind。
“InthesamemannerIhadworkedoutfortheManhattanElevatedRailroadasystemofelectrictrains，andhadthecontrolofeachcarcentredatoneplace——multiplecontrol。ThiswasafterwardworkedoutandmadepracticalbyFrankSprague。Igotupaslotcontactforstreetrailways，andhaveapatentonit——aslidingcontactinaslot。EdwardLauterbachwasconnectedwiththeThirdAvenueRailroadinNewYork——ascounsel——andItoldhimhewasmak-
ingahorriblemistakeputtinginthecable。Itoldhimtoletthecablestandstillandsendelectricitythroughit，andhewouldnothavetomovehundredsoftonsofmetalallthetime。Hewouldruethedaywhenheputthecablein。“Itcannotbedeniedthattheprophecywasfulfilled，forthecablewasthebeginningofthefrightfulfinancialcollapseofthesystem，andwastornoutinafewyearstomakewayforthetriumphant“trolleyintheslot。“
Incidentalglimpsesofthisworkarebothamusingandinteresting。Hughes，whowasworkingontheexperimentalroadwithMr。Edison，tellsthefollowingstory：“VillardsentJ。C。Henderson，oneofhismechanicalengineers，toseetheroadwhenitwasinoperation，andwewentdownoneday——Edison，Henderson，andI——andwentonthelocomotive。Edisonranit，andjustafterwestartedtherewasatrestlesixtyfeetlongandsevenfeetdeep，andEdisonputonallthepower。Whenwewentoveritwemusthavebeengoingfortymilesanhour，andIcouldseetheperspirationcomeoutonHenderson。Afterwegotoverthetrestleandstartedondownthetrack，Hendersonsaid：`WhenwegobackIwillwalk。IfthereisanymoreofthatkindofrunningIwon\'tbeinitmyself。\'“TothecorrespondenceofGrosvenorP。Lowreyweareindebtedforasimilarreminiscence，underdateofJune5，1880：“GoddardandIhavespentapartofthedayatMenlo，andallisglorious。
IhaveriddenatfortymilesanhouronMr。Edison\'selectricrailway——andweranoffthetrack。Iprotestedattherateofspeedoverthesharpcurves，designedtoshowthepoweroftheengine，butEdisonsaidtheyhaddoneitoften。Finally，whenthelasttripwastobetaken，IsaidIdidnotlikeit，butwouldgoalong。Thetrainjumpedthetrackonashortcurve，throwingKruesi，whowasdrivingtheengine，withhisfacedowninthedirt，andanothermaninacomicalsomersaultthroughsomeunderbrush。Edisonwasoffinaminute，jumpingandlaughing，anddeclaringitamostbeautifulaccident。Kruesigotup，hisfacebleedingandagooddealshaken；andI
shallneverforgettheexpressionofvoiceandfaceinwhichhesaid，withsomeforeignaccent：`Oh！
yes，pairfecklysafe。\'Fortunatelynootherhurtsweresuffered，andinafewminuteswehadthetrainonthetrackandrunningagain。“
Allthisrough-and-readydealingwithgradesandcurveswasnotmerehorse-play，buthadaseriouspurposeunderlyingit，everytriphavingitsrecordastosomefeatureofdefectorimprovement。OneparticularsetofexperimentsrelatingtosuchworkwasmadeonbehalfofvisitorsfromSouthAmerica，andweredoubtlessthefirsttestsofthekindmadeforthatcontinent，wherenowmanyfineelectricstreetandinterurbanrailwaysystemsareinoperation。
Mr。Edisonhimselfsuppliesthefollowingdata：
“Duringtheelectric-railwayexperimentsatMenloPark，wehadashortspuroftrackuponeofthesteepgullies。Theexperimentcameaboutinthisway。Bogota，thecapitalofColumbia，isreachedonmuleback——orwas——fromHondaontheheadwatersoftheMagdalenaRiver。Therewerepartieswhowantedtoknowiftransportationoverthemuleroutecouldnotbedonebyelectricity。Theysaidthegradeswereexcessive，anditwouldcosttoomuchtodoitwithsteamlocomotives，eveniftheycouldclimbthegrades。Isaid：`Well，itcan\'tbemuchmorethan45percent。；wewilltrythatfirst。Ifitwilldothatitwilldoanythingelse。\'Istartedat45percent。Igotupanelectriclocomotivewithagripontherailbywhichitwentupthe45percent。
grade。Thentheysaidthecurveswereveryshort。
Iputthecurvesin。Westartedthelocomotivewithnobodyonit，andgotuptotwentymilesanhour，takingthosecurvesofveryshortradius；butitwasweeksbeforewecouldpreventitfromrunningoff。
Wehadtobankthetracksuptoanangleofthirtydegreesbeforewecouldturnthecurveandstayon。
TheseSpanishpartieswereperfectlysatisfiedwecouldputinanelectricrailwayfromHondatoBogotasuccessfully，andthentheydisappeared。Ihaveneverseenthemsince。Asusual，Ipaidfortheexperiment。“
Inthespringof1883theElectricRailwayCompanyofAmericawasincorporatedintheStateofNewYorkwithacapitalof$2，000，000todevelopthepatentsandinventionsofEdisonandStephenD。Field，tothelatterofwhomthepracticalworkofactivedevelopmentwasconfided，andinJuneofthesameyearanexhibitwasmadeattheChicagoRailwayExposition，whichattractedattentionthroughoutthecountry，anddidmuchtostimulatethegrowinginterestinelectric-railwaywork。WiththeaidofMessrs。F。B。Rae，C。L。Healy，andC。O。MaillouxatrackandlocomotivewereconstructedforthecompanybyMr。Fieldandputinserviceinthegalleryofthemainexhibitionbuilding。Thetrackcurvedsharplyateitherendonaradiusoffifty-sixfeet，andthelengthwasaboutone-thirdofamile。Thelocomotivenamed“TheJudge，“afterJusticeField，anuncleofStephenD。Field，tookcurrentfromacentralrailbetweenthetwoouterrails，thatwerethereturncircuit，thecontactbeingarubbingwirebrushoneachsideofthe“thirdrail，“answeringthesamepurposeasthecontactshoeoflaterdate。Thelocomotiveweighedthreetons，wastwelvefeetlong，fivefeetwide，andmadeaspeedofninemilesanhourwithatrailercarforpassengers。StartingonJune5th，whentheexhibitionclosedonJune23dthistinybuttypicalroadhadoperatedforover118hours，hadmadeover446miles，andhadcarried26，805passengers。
AftertheexpositionclosedtheoutfitwastakenduringthesameyeartotheexpositionatLouisville，Kentucky，whereitwasalsosuccessful，carryingalargenumberofpassengers。ItdeservesnotethatatChicagoregularrailwayticketswereissuedtopayingpassengers，thefirsteveremployedonAmericanelectricrailways。
Withthismodestbutbrilliantdemonstration，towhichtheillustriousnamesofEdisonandFieldwereattached，begantheoutburstofexcitementoverelectricrailways，verymuchliketheerasofspeculationandexploitationthatattendedonlyafewyearsearliertheintroductionofthetelephoneandtheelectriclight，butwithsuchsignificantresultsthatthecapitalizationofelectricroadsinAmericaisnowover$4，000，000，000，ortwiceasmuchasthatoftheothertwoartscombined。Therewasatremendousrushintotheelectric-railwayfieldafter1883，andanoutburstofinventiveactivitythathasrarely，ifever，beenequalled。Itisremarkablethat，exceptSiemens，noEuropeanachievedfameinthisearlywork，whilefromAmericatheideasandappliancesofEdison，VanDepoele，Sprague，Field，Daft，andShorthavebeencarriedandadoptedallovertheworld。
Mr。EdisonwasconsultingelectricianfortheElectricRailwayCompany，butneitheradirectornoranexecutiveofficer。Justwhatthetroublewasastotheinternalmanagementofthecorporationitishardtodetermineaquarterofacenturylater；butitwasequippedwithallessentialelementstodominateanartinwhichafteritsfirsteffortsitremainedpracticallysupineanduseless，whileotherinterestsforgedaheadandreapedboththeprofitandtheglory。
DissensionsarosebetweentherepresentativesoftheFieldandEdisoninterests，andinApril，1890，theRailwayCompanyassigneditsrightstotheEdisonpatentstotheEdisonGeneralElectricCompany，recentlyformedbytheconsolidationofallthebranchesoftheEdisonlight，power，andmanufacturingindustryunderonemanagement。TheonlypatentrightsremainingtotheRailwayCompanywerethoseunderthreeFieldpatents，oneofwhich，withcontrollingclaims，wasputinsuitJune，1890，againsttheJamaica&BrooklynRoadCompany，acustomeroftheEdisonGeneralElectricCompany。
Thiswas，tosaytheleast，acuriousandanomaloussituation。Voluminousrecordsweremadebybothpartiestothesuit，andinthespringof1894thecasewasarguedbeforethelateJudgeTownsend，whowrotealongopiniondismissingthebillofcomplaint。[15]Thestudentwillfindthereinaverycompleteandcarefulstudyoftheearlyelectric-railwayart。Afterthisdecisionwasrendered，theElectricRailwayCompanyremainedforseveralyearsinamoribundcondition，andonthelastdayof1896itspropertywasplacedinthehandsofareceiver。InFebruaryof1897thereceiversoldthethreeFieldpatentstotheiroriginalowner，andheinturnsoldthemtotheWestinghouseElectricandManufacturingCompany。TheRailwayCompanythenwentintovoluntarydissolution，asadexampleoffailuretoseizetheopportunityatthepsychologicalmoment，andonthepartoftheinventortosecureanyadequatereturnforyearsofeffortandstruggleinfoundingoneofthegreatarts。
Neitherofthesemenwassquelchedbysuchacalamitousresult，butiftherewerenotsomethingofbitternessintheirfeelingsastheysurveywhathascomeoftheirwork，theywouldnotbehuman。
Asamatteroffact，Edisonretainedaverylivelyinterestinelectric-railwayprogresslongafterthepregnantdaysatMenloPark，oneofthebestevidencesofwhichisanarticleintheNewYorkElectricalEngineerofNovember18，1891，whichdescribessomeimportantandoriginalexperimentsinthedirectionofadaptingelectricalconditionstothelargercities。Theoverheadtrolleyhadbythattimebegunitsvictoriouscareer，buttherewasintensehostilitydisplayedtowarditinmanyplacesbecauseoftheinevitableincreaseinthenumberofoverheadwires，which，carrying，astheydid，acurrentofhighvoltageandlargequantity，wereregardedasamenacetolifeandproperty。Edisonhasalwaysmanifestedastrongobjectiontooverheadwiresincities，andurgedplacingthemunderground；andtheoutcryagainsttheoverhead“deadly“trolleymetwithhisinstantsympathy。Hisstudyoftheproblembroughthimtothedevelopmentofthemodern“substation，“
althoughthetwiststhatlaterevolutionshavegiventheideahaveleftitscarcelyrecognizable。
[15]See61Fed。Rep。655。
Mr。Villard，asPresidentoftheEdisonGeneralElectricCompany，requestedMr。Edison，aselectricianofthecompany，todeviseastreet-railwaysystemwhichshouldbeapplicabletothelargestcitieswheretheuseofthetrolleywouldnotbepermitted，wheretheslotconduitsystemwouldnotbeused，andwhere，ingeneral，thedetailsofconstructionshouldbereducedtothesimplestform。Thelimitsimposedpracticallyweresuchastorequirethatthesystemshouldnotcostmorethanacableroadtoinstall。Edisonrevertedtohisingeniouslightingplanofyearsearlier，andthussettledonamethodbywhichcurrentshouldbeconveyedfromthepowerplantathighpotentialtomotor-generatorsplacedbelowthegroundincloseproximitytotherails。
Thesesubstationswouldconvertthecurrentreceivedatapressureof，say，onethousandvoltstooneoftwentyvoltsavailablebetweenrailandrail，withacorrespondingincreaseinthevolumeofthecurrent。
Withtheutilizationofheavycurrentsatlowvoltageitbecamenecessary，ofcourse，todeviseapparatuswhichshouldbeabletopickupwithabsolutecertaintyonethousandamperesofcurrentatthispress-
urethroughtwoinchesofmud，ifnecessary。WithhiswontedactivityandfertilityEdisonsetaboutdevisingsuchacontact，andexperimentedwithmetalwheelsunderallconditionsofspeedandtrackconditions。
Itwasseveralmonthsbeforehecouldconveyonehundredamperesbymeansofsuchcontacts，butheworkedoutatlastasatisfactorydevicewhichwasequaltothetask。Thenextpointwastosecureajointbetweencontiguousrailssuchaswouldpermitofthepassageofseveralthousandampereswithoutintroducingundueresistance。Thiswasalsoaccomplished。
Objectionswerenaturallymadetorailsoutintheopenonthestreetsurfacecarryinglargecurrentsatapotentialoftwentyvolts。Itwassaidthatvehicleswithironwheelspassingoverthetracksandspanningthetworailswouldshort-circuitthecurrent，“chew“themselvesup，anddestroythedynamosgeneratingthecurrentbychokingallthattremendousamountofenergybackintothem。Edisontackledtheobjectionsquarelyandshort-circuitedhistrackwithsuchavehicle，butsucceededingettingonlyabouttwohundredamperesthroughthewheels，thelowvoltageandtheinsulatingpropertiesoftheaxle-
greasebeingsufficienttoaccountforsucharesult。
Anironbarwasalsoused，polished，andwithamanstandingonittoinsuresolidcontact；butonlyonethousandamperespassedthroughit——i。e。，theamountrequiredbyasinglecar，and，ofcourse，muchlessthanthecapacityofthegeneratorsabletooperateasystemofseveralhundredcars。
Furtherinterestingexperimentsshowedthattheexpectedlargeleakageofcurrentfromtherailsinwetweatherdidnotmaterialize。Edisonfoundthatundertheworstconditionswithawetandsaltedtrack，atapotentialdifferenceoftwentyvoltsbetweenthetworails，theextremelosswasonlytwoandone-halfhorse-power。Inthisrespectthephenomenonfollowedthesameruleasthattowhichtelegraphwiresaresubject——namely，thatthelossofinsulationisgreaterindamp，murkyweatherwhentheinsulatorsarecoveredwithwetdustthanduringheavyrainswhentheinsulatorsarethoroughlywashedbytheactionofthewater。Inlikemanneraheavyrain-stormcleanedthetracksfromtheaccumulationsduechieflytothedroppingsofthehorses，whichotherwiseservedlargelytoincreasetheconductivity。
Ofcourse，indryweatherthelossofcurrentwaspracticallynothing，and，underordinaryconditions，Edisonheld，hissystemwasinrespecttoleakageandtheproblemsofelectrolyticattackofthecurrentonadjacentpipes，etc。，asfullyinsulatedasthestandardtrolleynetworkoftheday。ThecostofhissystemMr。Edisonplacedatfrom$30，000to$100，000permileofdoubletrack，inaccordancewithlocalconditions，andinthisrespectcomparingveryfavorablywiththecablesystemsthensomuchinfavorforheavytraffic。Alltheargumentsthatcouldbeurgedinsupportofthisingenioussystemaretenableandlogicalatthepresentmoment；butthetrolleyhaditswayexceptonafewlineswheretheconduit-and-shoemethodwasadopted；andintheinterveningyearsthevolumeoftrafficcreatedandhandledbyelectricityincentresofdensepopulationhasbroughtintoexistencethemodernsubway。
Butdowntothemomentofthepreparationofthisbiography，Edisonhasretainedanactiveinterestintransportationproblems，andhislatestworkhasbeenthatofrevivingtheuseofthestoragebatteryforstreet-carpurposes。Atonetimetherewereanumberofstorage-batterylinesandcarsinoperationinsuchcitiesasWashington，NewYork，Chicago，andBoston；butthecostsofoperationandmaintenancewerefoundtobeinordinatelyhighascomparedwiththoseofthedirect-supplymethods，andthebatterycarsalldisappeared。Theneedforthemundermanyconditionsremained，as，forexample，inplacesinGreaterNewYorkwheretheoverheadtrolleywiresareforbiddenasobjectionable，andwherethegroundistoowetortoooftensubmergedtopermitoftheconduitwiththeslot。SomeoftheroadsinGreaterNewYorkhavebeenanxioustosecuresuchcars，and，asusual，themostresourcefulelectricalengineerandinventorofhistimeshasmadetheeffort。AspecialexperimentaltrackhasbeenlaidattheOrangelaboratory，andacarequippedwiththeEdisonstoragebatteryandotherdeviceshasbeenputundersevereandextendedtrialthereandinNewYork。
MenloPark，inruinanddecay，affordsnotracesoftheearlyEdisonelectric-railwaywork，butthecrudelittlelocomotivebuiltbyCharlesT。Hugheswasrescuedfromdestruction，andhasbecomethepropertyofthePrattInstitute，ofBrooklyn，towhosethousandsoftechnicalstudentsitisaconstantexampleandincentive。
Itwasloanedin1904totheAssociationofEdisonIlluminatingCompanies，andbyitexhibitedaspartofthehistoricalEdisoncollectionattheSt。LouisExposition。
EDISON
HISLIFEANDINVENTIONS
CHAPTERXIX
MAGNETICOREMILLINGWORK
DURINGtheHudson-FultoncelebrationofOctober，1909，BurgomasterVanLeeuwen，ofAmsterdam，memberofthedelegationsentofficiallyfromHollandtoescorttheHalfMoonandparticipateinthefunctionsoftheanniversary，paidavisittotheEdisonlaboratoryatOrangetoseetheinventor，whomayberegardedaspre-eminentamongthoseofDutchdescentinthiscountry。Found，asusual，hardatwork——thistimeonhiscementhouse，ofwhichheshowedtheironmolds——Edisontookoccasiontoremarkthatifhehadachievedanythingworthwhile，itwasduetotheobstinacyandpertinacityhehadinheritedfromhisforefathers。Towhichitmaybeaddedthatnotlessequallyhavethenatureofinheritanceandthequalityofatavismbeenexhibitedinhisextraordinarypredilectionforthemiller\'sart。
WhilethoseBatavianancestorsonthelowshoresoftheZuyderZeedevotedtheirenergiestogrindinggrain，hehasbeennotlessassiduousthantheyinreducingtherocksoftheearthitselftoflour。
AlthoughthisphaseofMr。Edison\'sdiverseactivitiesisnotasgenerallyknowntotheworldasmanyothersofamorepopularcharacter，themillingoflow-gradeauriferousoresandthemagneticseparationofironoreshavebeensubjectsofengrossinginterestandstudytohimformanyyears。Indeed，hiscomparativelyunknownenterpriseofseparatingmagneticallyandputtingintocommercialformlow-
gradeironore，ascarriedonatEdison，NewJersey，provedtobethemostcolossalexperimentthathehasevermade。
Ifapersonqualifiedtojudgewereaskedtoanswercategoricallyastowhetherornotthatenterprisewasafailure，hecouldtruthfullyanswerbothyesandno。Yes，inthatcircumstancesoverwhichMr。
Edisonhadnocontrolcompelledtheshuttingdownoftheplantattheverymomentofsuccess；andno，inthatthemechanicallysuccessfulandcommerciallypracticalresultsobtained，aftertheexerciseofstupendouseffortsandtheexpenditureofafortune，aresoconclusivethattheymustinevitablybetherelianceofmanyfutureiron-masters。Inotherwords，Mr。
Edisonwasatleastaquarterofacenturyaheadofthetimesintheworknowtobeconsidered。
Beforeproceedingtoaspecificdescriptionofthisremarkableenterprise，however，letusglanceatanearlyexperimentinseparatingmagneticironsandsontheAtlanticsea-shore：“SomeyearsagoIheardonedaythatdownatQuogue，LongIsland，therewereimmensedepositsofblackmagneticsand。Thiswouldbeveryvaluableiftheironcouldbeseparatedfromthesand。SoIwentdowntoQuoguewithoneofmyassistantsandsawthereformileslargebedsofblacksandonthebeachinlayersfromonetosixinchesthick——hundredsofthousandsoftons。Myfirstthoughtwasthatitwouldbeaveryeasymattertoconcentratethis，andIfoundIcouldsellthestuffatagoodprice。Iputupasmallplant，butjustasIgotitstartedatremendousstormcameup，andeverybitofthatblacksandwentouttosea。Duringthetwenty-eightyearsthathaveintervenedithasnevercomeback。“Thisincidentwasreallythepreludetothedevelopmentsetforthinthischapter。
IntheearlyeightiesEdisonbecamefamiliarwiththefactthattheEasternsteeltradewassufferingadisastrouschange，andthatbusinesswasslowlydriftingwestward，chieflybyreasonofthediscoveryandopeningupofenormousdepositsofhigh-gradeironoreintheupperpeninsulaofMichigan。Thisorecouldbeexcavatedverycheaplybymeansofimprovedminingfacilities，andtransportedatlowcosttolakeports。HencetheironandsteelmillseastoftheAlleghanies——compelledtorelyonlimitedlocaldepositsofBessemerore，anduponforeignoreswhichwereconstantlyrisinginvalue——begantosustainaseriouscompetitionwithWesternmills，eveninEasternmarkets。
Longbeforethissituationarose，ithadbeenrecognizedbyEasterniron-mastersthatsoonerorlaterthedepositsofhigh-gradeorewouldbeexhausted，and，inconsequence，therewouldensueacompellingnecessitytofallbackonthelow-grademagneticores。
Formanyyearsithadbeenamuch-discussedquestionhowtomaketheseoresavailablefortransporta-
tiontodistantfurnaces。Topayrailroadchargesonorescarryingperhaps80to90percent。ofuselessmaterialwouldbeprohibitive。Hencetheeliminationoftheworthless“gangue“byconcentrationoftheironparticlesassociatedwithit，seemedtobetheonlysolutionoftheproblem。
Manyattemptshadbeenmadeinby-gonedaystoconcentratetheironinsuchoresbywaterprocesses，butwithonlyapartialdegreeofsuccess。Theimpossibilityofobtainingauniformconcentratewasamostseriousobjection，hadtherenotindeedbeenotherdifficultieswhichrenderedthismethodcommerciallyimpracticable。Itisquitenatural，therefore，thattheideaofmagneticseparationshouldhaveoccurredtomanyinventors。Thuswefindnumerousinstancesthroughoutthelastcenturyofexperimentsalongthisline；andparticularlyinthelastfortyorfiftyyears，duringwhichvariousattemptshavebeenmadebyothersthanEdisontoperfectmagneticseparationandbringituptosomethinglikecommercialpractice。Atthetimehetookupthematter，however，nooneseemstohaverealizedthefullmeaningofthetremendousproblemsinvolved。
From1880to1885，whilestillverybusyinthedevelopmentofhiselectric-lightsystem，Edisonfoundopportunitytoplancrushingandseparatingmachinery。
Hisfirstpatentonthesubjectwasappliedforandissuedearlyin1880。Hedecided，aftermaturedeliberation，thatthemagneticseparationoflow-gradeoresonacolossalscaleatalowcostwastheonlypracticalwayofsupplyingthefurnacemanwithahighqualityofironore。Itwashisopinionthatitwascheapertoquarryandconcentrateleanoreinabigwaythantoattempttomine，underadversecircumstances，limitedbodiesofhigh-gradeore。
Heappreciatedfullytheseriousnatureofthegiganticquestionsinvolved；andhisplanswerelaidwithaviewtoexercisingtheutmosteconomyinthedesignandoperationoftheplantinwhichhecontemplatedtheautomatichandlingofmanythousandsoftonsofmaterialdaily。ItmaybestatedasbroadlytruethatEdisonengineeredtohandleimmensemassesofstuffautomatically，whilehispredecessorsaimedchieflyatcloseseparation。
Reducedtoitsbarest，crudestterms，thepropositionofmagneticseparationissimplicityitself。A
pieceoftheoremagnetitemaybereducedtopowderandtheoreparticlesseparatedtherefrombythehelpofasimplehandmagnet。ToelucidatethebasicprincipleofEdison\'smethod，letthecrushedorefallinathinstreampastsuchamagnet。Themagneticparticlesareattractedoutofthestraightlineofthefallingstream，andbeingheavy，gravitateinwardlyandfalltoonesideofapartitionplacedbelow。Thenon-magneticganguedescendsinastraightlinetotheothersideofthepartition。Thusacompleteseparationiseffected。
Simplethoughtheprincipleappears，itwasinitsapplicationtovastmassesofmaterialandinthesolvingofgreatengineeringproblemsconnectedtherewiththatEdison\'soriginalitymadeitselfmanifestintheconcentratingworksthatheestablishedinNewJersey，earlyinthenineties。Notonlydidhedevelopthoroughlytherefiningofthecrushedore，sothatafterithadpassedthefourhundredandeightymagnetsinthemill，theconcentratescameoutfinallycontaining91to93percent。ofironoxide，buthealsodevisedcollateralmachinery，methodsandprocessesallfundamentalintheirnature。Thesearetoonumeroustospecifyindetail，astheyextendedthroughoutthevariousramificationsoftheplant，buttheprincipalonesareworthyofmention，suchas：
Thegiantrollsforcrushing。
Intermediaterolls。
Three-highrolls。
Giantcranes215feetlongspan。
Verticaldryer。
Beltconveyors。
Airseparation。
Mechanicalseparationofphosphorus。
Briquetting。
ThatMr。Edison\'sworkwasappreciatedatthetimeismadeevidentbythefollowingextractfromanarticledescribingtheEdisonplant，publishedinTheIronAgeofOctober28，1897；inwhich，aftermentioninghisstrugglewithadverseconditions，itsays：“Thereisverylittlethatisshowy，fromthepopularpointofview，inthegiganticworkwhichMr。Edisonhasdoneduringtheseyears，buttothosewhoarecapableofgraspingthedifficultiesencountered，Mr。Edisonappearsinthenewlightofabrilliantconstructingengineergrapplingwithtechnicalandcommercialproblemsofthehighestorder。Hisgeniusasaninventorisrevealedinmanydetailsofthegreatconcentratingplant……Buttoourmind，originalityofthehighesttypeasaconstructoranddesignerappearsintheboldwayinwhichhesweepsasideacceptedpracticeinthisparticularfieldandattainsresultsnothithertoapproached。Hepursuesmethodsinore-dressingatwhichthosewhoaretrainedintheusualpracticemaywellstandaghast。
Butconsideringthespecialfeaturesoftheproblemstobesolved，hismethodswillbeacceptedasthoseeconomicallywiseandexpedient。“
Acursoryglanceattheseproblemswillrevealtheirimport。Mountainsmustbereducedtodust；allthisdustmustbehandledindetail，sotospeak，andfromitmustbeseparatedthefineparticlesofironconstitutingonlyone-fourthorone-fifthofitsmass；
andthenthisiron-oredustmustbeputintosuchshapethatitcouldbecommerciallyshippedandused。
OneofthemostinterestingandstrikinginvestigationsmadebyEdisoninthisconnectionisworthyofnote，andmayberelatedinhisownwords：“I
feltcertainthattheremustbelargebodiesofmagnetiteintheEast，whichifcrushedandconcentratedwouldsatisfythewantsoftheEasternfurnacesforsteel-making。HavingdeterminedtoinvestigatethemountainregionsofNewJersey，Iconstructedaverysensitivemagneticneedle，whichwoulddiptowardtheearthifbroughtoveranyconsiderablebodyofmagneticironore。OneofmylaboratoryassistantswentoutwithmeandwevisitedmanyoftheminesofNewJersey，butdidnotfinddepositsofanymagnitude。
Oneday，however，aswedroveoveramountainrange，notknownasiron-bearingland，Iwasastonishedtofindthattheneedlewasstronglyattractedandremainedso；thusindicatingthatthewholemountainwasunderlaidwithvastbodiesofmagneticore。
“Iknewitwasacommercialproblemtoproducehigh-gradeBessemerorefromthesedeposits，andtookstepstoacquirealargeamountoftheproperty。
IalsoplannedagreatmagneticsurveyoftheEast，andIbelieveitremainsthemostcomprehensiveofitskindyetperformed。IhadanumberofmensurveyastripreachingfromLowerCanadatoNorthCarolina。Theonlyinstrumentweusedwasthespecialmagneticneedle。WestartedinLowerCanadaandtravelledacrossthelineofmarchtwenty-fivemiles；thenadvancedsouthonethousandfeet；thenbackacrossthelineofmarchagaintwenty-fivemiles；
thensouthanotherthousandfeet，acrossagain，andsoon。ThusweadvancedallthewaytoNorthCarolina，varyingourcross-countrymarchfromtwototwenty-fivemiles，accordingtogeologicalformation。
Ourmagneticneedleindicatedthepresenceandrichnessoftheinvisibledepositsofmagneticore。
Wekeptminuterecordsoftheseindications，andwhenthesurveywasfinishedwehadexactinformationofthedepositsineverypartofeachStatewehadpassedthrough。Wealsoknewthewidth，length，andapproximatedepthofeveryoneofthesedeposits，whichwereenormous。
“Theamountoforedisclosedbythissurveywassimplyfabulous。HowmuchsomaybejudgedfromthefactthatinthethreethousandacresimmediatelysurroundingthemillsthatIafterwardestablishedatEdisontherewereover200，000，000tonsoflow-
gradeore。Ialsosecuredsixteenthousandacresinwhichthedepositwasproportionatelyaslarge。
ThesefewacresalonecontainedsufficientoretosupplythewholeUnitedStatesirontrade，includingexports，forseventyyears。“
Givenamountainofrockcontainingonlyone-fifthtoone-fourthmagneticiron，thebroadproblemconfrontingEdisonresolveditselfintothreedistinctparts——first，toteardownthemountainbodilyandgrindittopowder；second，toextractfromthispowdertheparticlesofironmingledinitsmass；
and，third，toaccomplishtheseresultsatacostsufficientlylowtogivetheproductacommercialvalue。
Edisonrealizedfromthestartthatthetruesolutionofthisproblemlayinthecontinuoustreatmentofthematerial，withthemaximumemploymentofnaturalforcesandtheminimumofmanuallaborandgeneratedpower。Hence，allhisconceptionsfollowedthisgeneralprinciplesofaithfullyandcompletelythatwefindintheplantembodyinghisideastheforcesofmomentumandgravitysteadilyinharnessandkeepingthetracestaut；whiletherewasnotouchofthehumanhanduponthematerialfromthebeginningofthetreatmenttoitsfinish——thestaffbeingemployedmainlytokeepwatchonthecorrectworkingofthevariousprocesses。
Itishardlynecessarytodevotespacetothebeginningsoftheenterprise，althoughtheyarefullofinterest。Theyserved，however，toconvinceEdisonthatifheeverexpectedtocarryouthisschemeontheextensivescaleplanned，hecouldnotdependuponthemarkettosupplysuitablemachineryforimportantoperations，butwouldbeobligedtodeviseandbuildithimself。Thus，outsidethesteam-
shovelandsuchstapleitemsasengines，boilers，dynamos，andmotors，allofthediverseandcomplexmachineryoftheentireconcentratingplant，assubsequentlycompleted，wasdevisedbyhimespeciallyforthepurpose。Thenecessityforthiswasduetothemanyradicalvariationsmadefromacceptedmethods。
Nosuchdeparturewasasradicalasthatofthemethodofcrushingtheore。Existingmachineryforthispurposehadbeendesignedonthebasisofminingmethodstheninvogue，bywhichtherockwasthoroughlyshatteredbymeansofhighexplosivesandreducedtopiecesofonehundredpoundsorless。Thesepieceswerethencrushedbypowerdirectlyapplied。Ifaconcentratingmill，plannedtotreatfiveorsixthousandtonsperday，weretobeoperatedonthisbasistheinvestmentincrushersandthesupplyofpowerwouldbeenormous，tosaynothingoftheriskoffrequentbreakdownsbyreasonofmultiplicityofmachineryandparts。Fromaconsiderationofthesefacts，andwithhisusualtendencytoupsettraditionalobservances，Edisonconceivedtheboldideaofconstructinggiganticrollswhich，bytheforceofmomentum，wouldbecapableofcrushingindividualrocksofvastlygreatersizethaneverbeforeattempted。
Hereasonedthattheadvantagesthusobtainedwouldbefourfold：aminimumofmachineryandparts；
greatercompactness；asavingofpower；andgreatereconomyinmining。Asthislast-namedoperationprecedesthecrushing，letusfirstconsideritasitwasprojectedandcarriedonbyhim。
Perhapsquarryingwouldbeabettertermthanmininginthiscase，asEdison\'splanwastoapproachtherockandtearitdownbodily。Thefaiththat“movesmountains“hadanewopportunity。Inworkofthisnatureithadbeencustomary，asabovestated，todependuponahighexplosive，suchasdynamite，toshatterandbreaktheoretolumpsofonehundredpoundsorless。This，however，hedeemedtobeamostuneconomicalprocess，forenergystoredasheatunitsindynamiteat$260pertonwasmuchmoreexpensivethanthatofcaloriesinatonofcoalat$3perton。Hence，hebelievedthatonlytheminimumofworkshouldbedonewiththecostlyexplosive；and，therefore，plannedtousedynamitemerelytodislodgegreatmassesofrock，anddependeduponthesteam-shovel，operatedbycoalundertheboiler，todisplace，handle，andremovetherockindetail。ThiswastheplanthatwassubsequentlyputintopracticeinthegreatworksatEdison，NewJersey。
Aseriesofthree-inchholestwentyfeetdeepweredrilledeightfeetapart，abouttwelvefeetbackoftheore-bank，andintothesewereinserteddynamitecartridges。Theblastwoulddislodgethirtytothirty-
fivethousandtonsofrock，whichwasscoopedupbygreatsteam-shovelsandloadedontoskipscarriedbyalineofcarsonanarrow-gaugerailroadrunningtoandfromthecrushingmill。Herethematerialwasautomaticallydeliveredtothegiantrolls。Theproblemincludedhandlingandcrushingthe“runofthemine，“withoutselection。Thesteam-shoveldidnotdiscriminate，butpickeduphandilysinglepiecesweighingfiveorsixtonsandloadedthemontheskipswithquantitiesofsmallerlumps。Whentheskipsarrivedatthegiantrolls，theircontentsweredumpedautomaticallyintoasuperimposedhopper。Therollswerewellnamed，forwithear-
splittingnoisetheybrokeupinafewsecondsthegreatpiecesofrocktossedinfromtheskips。
Itisnoteasytoappreciatetothefullthedaringexemplifiedinthesegreatcrushingrolls，orrather“rock-crackers，“withouthavingwatchedtheminoperationdeliveringtheir“solar-plexus“blows。Itwasonlyasonemightstandintheirvicinityandhearthethunderousroaraccompanyingthesmashingandrendingofthemassiverocksastheydisappearedfromviewthatthemindwasoverwhelmedwithasenseofthemagnificentproportionsofthisoperation。Theenormousforceexertedduringthisprocessmaybeillustratedfromthefactthatduringitsdevelopment，inrunningoneoftheearlyformsofrolls，piecesofrockweighingmorethanhalfatonwouldbeshotupintheairtoaheightoftwentyortwenty-
fivefeet。
Thegiantrollsweretwosolidcylinders，sixfeetindiameterandfivefeetlong，madeofcastiron。Tothefacesoftheserollswereboltedaseriesofheavy，chilled-ironplatescontaininganumberofprojectingknobstwoincheshigh。Eachrollhadalsotworowsoffour-inchknobs，intendedtostrikeaseriesofhammer-likeblows。Therollsweresetfacetofacefourteeninchesapart，inaheavyframe，andthetotalweightwasonehundredandthirtytons，ofwhichseventytonswereinmovingparts。Thespacebetweenthesetworollsallowedpiecesofrockmeasuringlessthanfourteeninchestodescendtoothersmallerrollsplacedbelow。Thegiantrollswerebelt-driven，inoppositedirections，throughfrictionclutches，althoughthebeltwasnotdependeduponfortheactualcrushing。
Previoustothedumpingofaskip，therollswerespeededuptoacircumferentialvelocityofnearlyamileaminute，thusimpartingtothemtheterrificmomentumthatwouldbreakupeasilyinafewsecondsbouldersweighingfiveorsixtonseach。Itwasasthougharockofthissizehadgotinthewayoftwoexpresstrainstravellinginoppositedirectionsatnearlysixtymilesanhour。Inotherwords，itwasthekineticenergyoftherollsthatcrumbleduptherockswithpile-drivereffect。Thissuddenstrainmighthavetendedtostoptheenginedrivingtherolls；butbyaningeniousclutcharrangementthebeltwasreleasedatthemomentofresistanceintherollsbyreasonoftherocksfallingbetweenthem。
Theactofbreakingandcrushingwouldnaturallydecreasethetremendousmomentum，butaftertherockwasreducedandthepieceshadpassedthrough，thebeltwouldagaincomeintoplay，andoncemorespeeduptherollsforarepetitionoftheirregularprize-fighterduty。
Onleavingthegiantrollstherocks，havingbeenreducedtopiecesnotlargerthanfourteeninches，passedintotheseriesof“IntermediateRolls“ofsimilarconstructionandoperation，bywhichtheywerestillfurtherreduced，andagainpassedontothreeothersetsofrollsofsmallerdimensions。Theselatterrollswerealsoface-linedwithchilled-ironplates；but，unlikethelargerones，werepositivelydriven，reducingtherocktopiecesofaboutone-half-inchsize，orsmaller。Thewholecrushingoperationofreductionfrommassiveboulderstosmallpebblypieceshavingbeendoneinlesstimethanthetellinghasoccupied，theproductwasconveyedtothe“Dryer，“atowerninefeetsquareandfiftyfeethigh，heatedfrombelowbygreatopenfurnacefires。Alldowntheinsidewallsofthistowerwereplacedcast-ironplates，ninefeetlongandsevenincheswide，arrangedalternatelyin“fish-ladder“fashion。Thecrushedrock，beingdeliveredatthetop，wouldfalldownfromplatetoplate，constantlyexposingdifferentsurfacestotheheat，untilitlandedcompletelydriedinthelowerportionofthetower，whereitfellintoconveyorswhichtookituptothestock-house。
ThismethodofdryingwasoriginalwithEdison。
Atthetimethisadjuncttotheplantwasrequired，thebestdryeronthemarketwasofarotarytype，whichhadacapacityofonlytwentytonsperhour，withtheexpenditureofconsiderablepower。AsEdisonhaddeterminedupontreatingtwohundredandfiftytonsormoreperhour，hedecidedtodeviseanentirelynewtypeofgreatcapacity，requiringaminimumofpowerforelevatingthematerial，anddependingupontheforceofgravityforhandlingitduringthedryingprocess。Alongseriesofexperimentsresultedintheinventionofthetowerdryerwithacapacityofthreehundredtonsperhour。
Therock，brokenupintopiecesaboutthesizeofmarbles，havingbeendriedandconveyedtothestock-house，thesurplusagewasautomaticallycarriedoutfromtheotherendofthestock-housebycon-
veyors，topassthroughthenextprocess，bywhichitwasreducedtoapowder。ThemachineryforaccomplishingthisresultrepresentsanotherinterestingandradicaldepartureofEdisonfromacceptedusage。Hehadinvestigatedallthecrushing-machinesonthemarket，andtriedallhecouldget。Hefoundthemallgreatlylackingineconomyofoperation；indeed，thehighestresultsobtainablefromthebestwere18
percent。ofactualwork，involvingalossof82percent。
byfriction。Hisnaturerevoltedatsuchanimmenselossofpower，especiallyasheproposedthecrushingofvastquantitiesofore。Thus，hewasobligedtobeginagainatthefoundation，andhedevisedacrushing-machinewhichwassubsequentlynamedthe“Three-HighRolls，“andwhichpracticallyreversedtheabovefigures，asitdeveloped84percent。ofworkdonewithonly16percent。lossinfriction。
Abriefdescriptionofthisremarkablemachinewillprobablyinterestthereader。Inthetwoendpiecesofaheavyironframeweresetthreerolls，orcylinders——oneinthecentre，anotherbelow，andtheotherabove——allthreebeinginaverticalline。Theserollswereofcastironthreefeetindiameter，havingchilled-ironsmoothface-platesofconsiderablethickness。
Thelowestrollwassetinafixedbearingatthebottomoftheframe，and，therefore，couldonlyturnaroundonitsaxis。Themiddleandtoprollswerefreetomoveupordownfromandtowardthelowerroll，andtheshaftsofthemiddleandupperrollsweresetinaloosebearingwhichcouldslipupanddownintheironframe。Itwillbeapparent，therefore，thatanymaterialwhichpassedinbetweenthetopandthemiddlerolls，andthemiddleandbottomrolls，couldbegroundasfineasmightbedesired，dependingentirelyupontheamountofpressureappliedtothelooserolls。Inoperationthematerialpassedfirstthroughtheupperandmiddlerolls，andthenbetweenthemiddleandlowestrolls。
Thispressurewasappliedinamostingeniousmanner。
Ontheendsoftheshaftsofthebottomandtoprollstherewerecylindricalsleeves，orbearings，havingsevensheaves，inwhichwasrunahalf-inchendlesswirerope。Thisropewaswoundseventimesoverthesheavesasabove，andledupwardandoverasingle-
groovesheavewhichwasoperatedbythepistonofanaircylinder，andinthismannerthepressurewasappliedtotherolls。Itwillbeseen，therefore，thatthesystemconsistedinasingleropepassedoversheavesandsoarrangedthatitcouldbevariedinlength，thusprovidingforelasticityinexertingpressureandregulatingitasdesired。Theefficiencyofthissystemwasincomparablygreaterthanthatofanyotherknowncrusherorgrinder，forwhileapressureofonehundredandtwenty-fivethousandpoundscouldbeexertedbytheserolls，frictionwasalmostentirelyeliminatedbecausetheupperandlowerrollbearingsturnedwiththerollsandrevolvedinthewirerope，whichconstitutedthebearingproper。
ThesamecautiousforesightexercisedbyEdisoninprovidingasafetydevice——thefuse——topreventfiresinhiselectric-lightsystem，wasagaindisplayedinthisconcentratingplant，where，tosavepossibleinjurytoitsexpensiveoperatingparts，hedevisedananalogousfactor，providingallthecrush-
ingmachinerywithcloselycalculated“safetypins，“
which，onbeingoverloaded，wouldshearoffandthusstopthemachineatonce。
Therockshavingthusbeenreducedtofinepowder，themasswasreadyforscreeningonitswaytothemagneticseparators。HereagainEdisonreversedpriorpracticebydiscardingrotaryscreensanddevisingaformoftowerscreen，which，besideshavingaverylargeworkingcapacitybygravity，eliminatedallpowerexceptthatrequiredtoelevatethematerial。
Thescreeningprocessallowedthefinestpartofthecrushedrocktopasson，byconveyorbelts，tothemagneticseparators，whilethecoarserparticleswereinlikemannerautomaticallyreturnedtotherollsforfurtherreduction。
Inanarrativenotintendedtobestrictlytechnical，itwouldprobablytirethereadertofollowthismaterialindetailthroughthenumerousstepsattendingthemagneticseparation。Thesemaybeseeninadiagramreproducedfromtheabove-namedarticleintheIronAge，andsupplementedbythefollowingextractfromtheElectricalEngineer，NewYork，October28，1897：“Atthestarttheweakestmagnetatthetopfreesthepurestparticles，andthesecondtakescareofothers；butthethirdcatchesthosetowhichrockadheres，andwillextractparticlesofwhichonlyone-eighthisiron。Thisbatchofmaterialgoesbackforanothercrushing，sothateverythingissubjectedtoanequalityofrefining。Wearenowinsightofthereal`concentrates，\'whichareconveyedtodryerNo。2fordryingagain，andarethendeliveredtothefifty-meshscreens。Whateverisfineenoughgoesthroughtotheeight-inchmagnets，andtheremaindergoesbackforrecrushing。Belowtheeight-
inchmagnetsthedustisblownoutoftheparticlesmechanically，andtheythengotothefour-inchmagnetsforfinalcleansingandseparation……Obviously，ateachstepthepercentageoffelsparandphosphorusislessandlessuntilinthefinalconcentratesthepercentageofironoxideis91to93percent。
Asintimatedattheoutset，thetailingswillbe75percent。oftherocktakenfromtheveinsofore，sothateveryfourtonsofcrude，raw，low-gradeorewillhaveyieldedroughlyonetonofhigh-gradeconcentrateandthreetonsofsand，thelatteralsohavingitsvalueinvariousways。“
Thissandwastransportedautomaticallybybeltconveyorstotherearoftheworkstobestoredandsold。Beingsharp，crystalline，andeveninquality，itwasavaluableby-product，findingareadysaleforbuildingpurposes，railwaysand-boxes，andvariousindustrialuses。Theconcentrate，infinepowderyform，wasdeliveredinsimilarmannertoastock-
house。
Astothenextstepintheprocess，wemaynowquoteagainfromthearticleintheIronAge：“WhileMr。Edisonandhisassociateswereworkingontheproblemofcheapconcentrationofironore，anaddeddifficultyfacedtheminthepreparationoftheconcentratesforthemarket。Furnacemenobjecttomorethanaverysmallproportionoffineoreintheirmixtures，particularlywhentheoreismagnetic，noteasilyreduced。Theproblemtobesolvedwastomarketanagglomeratedmaterialsoastoavoidthedrawbacksoffineore。Theagglomeratedproductmustbeporoussoastoaffordaccessofthefurnace-
reducinggasestotheore。Itmustbehardenoughtobeartransportation，andtocarrythefurnaceburdenwithoutcrumblingtopieces。Itmustbewaterproof，toacertainextent，becauseconsiderationsconnectedwithsecuringlowratesoffreightmakeitnecessarytobeabletoshiptheconcentratestomarketinopencoalcars，exposedtosnowandrain。InmanyrespectstheattainmentofthesesomewhatconflictingendswasthemostperplexingoftheproblemswhichconfrontedMr。Edison。Theagglomerationoftheconcentrateshavingbeendecidedupon，twootherconsiderations，notmentionedabove，wereofprimaryimportance——first，tofindasuitablecheapbindingmaterial；and，second，itsnaturemustbesuchthatverylittlewouldbenecessarypertonofconcentrates。
Thesesevererequirementswerestaggering，butMr。Edison\'scouragedidnotfalter。Althoughitseemedawell-nighhopelesstask，heenteredupontheinvestigationwithhisusualoptimismandvim。
Aftermanymonthsofunremittingtoilandresearch，andthetrialofthousandsofexperiments，thegoalwasreachedinthecompletionofasuccessfulformulaforagglomeratingthefineoreandpressingitintobriquettesbyspecialmachinery。“
Thiswasthefinalprocessrequisiteforthemakingofacompletedcommercialproduct。Itspractice，ofcourse，necessitatedtheadditionofanentirelynewdepartmentoftheworks，whichwascarriedintoeffectbytheconstructionandinstallationofthenovelmixingandbriquettingmachinery，togetherwithex-
tensionsoftheconveyors，withwhichtheplanthadalreadybeenliberallyprovided。
Brieflydescribed，theprocessconsistedinmixingtheconcentrateswiththespecialbindingmaterialinmachinesofanentirelynewtype，andinpassingtheresultantpastymassintothebriquettingmachines，whereitwaspressedintocylindricalcakesthreeinchesindiameterandoneandahalfinchesthick，undersuccessivepressuresof7800，14，000，and60，000
pounds。Eachmachinemadethesebriquettesattherateofsixtyperminute，anddroppedthemintobucketconveyorsbywhichtheywerecarriedintodryingfurnaces，throughwhichtheymadefiveloops，andwerethendeliveredtocross-conveyorswhichcarriedthemintothestock-house。Attheendofthisprocessthebriquettesweresohardthattheywouldnotbreakorcrumbleinloadingonthecarsorintransportationbyrail，whiletheyweresoporousastobecapableofabsorbing26percent。oftheirownvolumeinalcohol，butrepellingwaterabsolutely——
perfect“oldsoaks。“
Thus，withnever-failingpersistenceandpatience，coupledwithintensethoughtandhardwork，Edisonmetandconquered，onebyone，thecomplexdifficultiesthatconfrontedhim。Hesucceededinwhathehadsetouttodo，anditisnowtobenotedthattheproducthehadstrivensosedulouslytoobtainwasahighlycommercialone，fornotonlydidthebriquettesofconcentratedorefulfilthepurposeoftheircreation，butinuseactuallytendedtoincreasetheworkingcapacityofthefurnace，asthefollowingtest，quotedfromtheIronAge，October28，1897，willattest：“Theonlytrialofanymagnitudeofthebriquettesintheblast-furnacewascarriedthroughearlythisyearattheCraneIronWorks，Catasauqua，Pennsylvania，byLeonardPeckitt。
“Thefurnaceatwhichthetestwasmadeproducesfromonehundredtoonehundredandtentonsperdaywhenrunningontheordinarymixture。Thechargingofbriquetteswasbegunwithapercentageof25percent。，andwascarriedupto100percent。
Thefollowingistherecordoftheresults：
RESULTSOFWORKINGBRIQUETTESATTHECRANEFURNACE
QuantityofPhos-Man-
DateBriquetteTonsSilicaphorusSulphurganeseWorkingPerCent。
January5th251042。7700。8300。0180。500
January6th371/241/22。62007400。0180。350
January7th501381/22。5720。5800。0150。200
January8th751191。8440。2640。0220。200
January9th1001381/21。7120。1470。0380。185
“Onthe9th，at5P。M。，thebriquetteshavingbeennearlyexhausted，thepercentagewasdroppedto25percent。，andonthe10ththeoutputdroppedto120tons，andonthe11ththefurnacehadresumedtheusualworkontheregularstandardores。
“Thesefiguresprovethattheyieldofthefurnaceisconsiderablyincreased。TheCranetrialwastooshorttosettlethequestiontowhatextenttheincreaseinproductmaybecarried。Thisincreaseinoutput，ofcourse，meansareductioninthecostoflaborandofgeneralexpenses。
“Therichnessoftheoreanditspurityofcourseaffectthelimestoneconsumption。InthecaseoftheCranetrialtherewasareductionfrom30percent。to12percent。oftheorecharge。
“Finally，thefuelconsumptionisreduced，whichinthecaseoftheEasternplants，withtheirrelativelycostlycoke，isaveryimportantconsideration。ItisregardedaspossiblethatEasternfurnaceswillbeabletouseasmallerproportionofthecostliercokeandcorrespondinglyincreaseinanthracitecoal，whichisacheaperfuelinthatsection。Sofarasfoundryironisconcerned，theexperienceatCatasauqua，Pennsylvania，briefasithasbeen，showsthatastrongerandtoughermetalismade。“
Edisonhimselftellsaninterestinglittlestoryinthisconnection，whenheenjoyedtheactivehelpofthatnoblecharacter，JohnFritz，thedistinguishedinventorandpioneerofthemodernsteelindustryinAmerica。Hesays：“WhenIwasstrugglingalongwiththeiron-oreconcentration，Iwenttoseeseveralblast-furnacementoselltheoreatthemarketprice。