WhenBiela’scometgavetheinhabitantsoftheearthsuchafrightin1832，itreallydidnotcomewithinfiftymillionsofmilesofus。Eventhegreatcometthroughwhosefilmytailtheearthpassedin1861wasitselffourteenmillionsofmilesaway。Theordinarymind，schooledtomeasurespacebythetinystretchesofapygmyplanet，cannotgrasptheimportofsuchdistances；yetthesearemereunitsofmeasurecomparedwiththevaststretchesofsiderealspace。Werethecometwhichhurtlespastusataspeedof，say，ahundredmilesasecondtocontinueitsmadflightuncheckedstraightintothevoidofspace，itmustflyonitsfrigidwayeightthousandyearsbeforeitcouldreachtheverynearestofourneighborstars；andeventhenitwouldhavepenetratedbutamerearm’s-lengthintothevistaswhereliethedozenorsoofsiderealresidentsthatarenextbeyond。Eventothetrainedmindsuchdistancesareonlyvaguelyimaginable。Yettheastronomerofourcenturyhasreachedoutacrossthisunthinkablevoidandbroughtbackmanyasecretwhichourpredecessorsthoughtforeverbeyondhumangrasp。
AtentativeassaultuponthisstrongholdofthestarswasbeingmadebyHerschelatthebeginningofthecentury。In1802thatgreatestofobservingastronomersannouncedtotheRoyalSocietyhisdiscoverythatcertaindoublestarshadchangedtheirrelativepositionstowardsoneanothersincehefirstcarefullychartedthemtwentyyearsbefore。Hithertoithadbeensupposedthatdoublestarsweremereopticaleffects。Nowitbecameclearthatsomeofthem，atanyrate，aretrue\"binarysystems，\"linkedtogetherpresumablybygravitationandrevolvingaboutoneanother。Halleyhadshown，three-quartersofacenturybefore，thatthestarshaveanactualor\"proper\"motioninspace；
Herschelhimselfhadprovedthatthesunsharesthismotionwiththeotherstars。Herewasanothershiftofplace，hithertoquiteunsuspected，tobereckonedwithbytheastronomerinfathomingsiderealsecrets。
DoubleStarsWhenJohnHerschel，theonlysonandtheworthysuccessorofthegreatastronomer，beganstar-gazinginearnest，aftergraduatingseniorwrangleratCambridge，andmakingtwoorthreetentativeprofessionalstartsinotherdirectionstowhichhisversatilegeniusimpelledhim，hisfirstextendedworkwastheobservationofhisfather’sdoublestars。Hisstudies，inwhichatfirsthehadthecollaborationofMr。JamesSouth，broughttolightscoresofhithertounrecognizedpairs，andgavefreshdataforthecalculationoftheorbitsofthoselongerknown。SoalsodidtheindependentresearchesofF。G。W。Struve，theenthusiasticobserverofthefamousRussianobservatoryattheuniversityofDorpat，andsubsequentlyatPulkowa。Utilizingdatagatheredbytheseobservers，M。Savary，ofParis，showed，in1827，thattheobservedellipticalorbitsofthedoublestarsareexplicablebytheordinarylawsofgravitation，thusconfirmingtheassumptionthatNewton’slawsapplytothesesiderealbodies。Henceforththerecouldbenoreasontodoubtthatthesameforcewhichholdsterrestrialobjectsonourglobepullsateachandeveryparticleofmatterthroughoutthevisibleuniverse。
Thepioneerexplorersofthedoublestarsearlyfoundthatthesystemsintowhichthestarsarelinkedarebynomeansconfinedtosinglepairs。Oftenthreeorfourstarsarefoundthuscloselyconnectedintogravitationsystems；indeed，thereareallgradationsbetweenbinarysystemsandgreatclusterscontaininghundredsoreventhousandsofmembers。Itisknown，forexample，thatthefamiliarclusterofthePleiadesisnotmerelyanopticalgrouping，aswasformerlysupposed，butanactualfederationofassociatedstars，sometwothousandfivehundredinnumber，onlyafewofwhicharevisibletotheunaidedeve。Andthemorecarefullythemotionsofthestarsarestudied，themoreevidentitbecomesthatwidelyseparatedstarsarelinkedtogetherintoinfinitelycomplexsystems，asyetbutlittleunderstood。Atthesametime，allinstrumentaladvancestendtoresolvemoreandmoreseeminglysinglestarsintoclosepairsandminorclusters。ThetwoHerschelsbetweenthemdiscoveredsomethousandsoftheseclosemultiplesystems；Struveandothersincreasedthelisttoabovetenthousand；andMr。S。W。
Burnham，oflateyearsthemostenthusiasticandsuccessfulofdouble-starpursuers，addedathousandnewdiscoverieswhilehewasstillanamateurinastronomy，andbyprofessionthestenographerofaChicagocourt。
Clearlytheactualnumberofmultiplestarsisbeyondallpresentestimate。
TheelderHerschel’searlystudiesofdoublestarswereundertakeninthehopethattheseobjectsmightaidhiminascertainingtheactualdistanceofastar，throughmeasurementofitsannualparallax——thatistosay，oftheanglewhichthediameteroftheearth’sorbitwouldsubtendasseenfromthestar。Theexpectationwasnotfulfilled。Theapparentshiftofpositionofastarasviewedfromoppositesidesoftheearth’sorbit，fromwhichtheparallaxmightbeestimated，issoextremelyminutethatitprovedutterlyinappreciable，eventothealmostpreternaturallyacutevisionofHerschel，withtheaidofanyinstrumentalmeansthenatcommand。Sotheproblemofstardistancealluredandeludedhimtotheend，andhediedin1822withoutseeingiteveninprospectofsolution。
Hisestimateoftheminimumdistanceoftheneareststar，basedthoughitwasonthefallacioustestofapparentbrilliancy，wasasingularlysagaciousone，butitwasatbestascientificguess，notascientificmeasurement。
TheDistanceoftheStarsJustaboutthistime，however，agreatopticiancametotheaidoftheastronomers。JosephFraunhoferperfectedtherefractingtelescope，asHerschelhadperfectedthereflector，andinventedawonderfullyaccurate\"heliometer，\"orsun-measurer。Withtheaidoftheseinstrumentstheoldandalmostinfinitelydifficultproblemofstardistancewassolved。In1838BesselannouncedfromtheKonigsbergobservatorythathehadsucceeded，aftermonthsofeffort，indetectingandmeasuringtheparallaxofastar。Similarclaimshadbeenmadeoftenenoughbefore，alwaystoprovefallaciouswhenputtofurthertest；butthistimetheannouncementcarriedtheauthorityofoneofthegreatestastronomersoftheage，andscepticismwassilenced。
NordidBessel’sachievementlongawaitcorroboration。
Indeed，assooftenhappensinfieldsofdiscovery，twootherworkershadalmostsimultaneouslysolvedthesameproblem——StruveatPulkowa，wherethegreatRussianobservatory，whichsolongheldthepalmoverallothers，hadnowbeenestablished；andThomasHenderson，thenworkingattheCapeofGoodHope，butafterwardstheAstronomerRoyalofScotland。
Henderson’sobservationshadactualprecedenceinpointoftime，butBessel’smeasurementsweresomuchmorenumerousandauthoritativethathehasbeenuniformlyconsideredasdeservingthechiefcreditofthediscovery，whichpriorityofpublicationsecuredhim。
Byanoddchance，thestaronwhichHenderson’sobservationsweremade，andconsequentlythefirststartheparallaxofwhichwasevermeasured，isournearestneighborinsiderealspace，being，indeed，sometenbillionsofmilesnearerthantheonenextbeyond。Yeteventhisneareststarismorethantwohundredthousandtimesasremotefromusasthesun。Thesun’slightflashestotheearthineightminutes，andtoNeptuneinaboutthreeandahalfhours，butitrequiresthreeandahalfyearstosignalAlphaCentauri。Andasforthegreatmajorityofthestars，hadtheybeenblottedoutofexistencebeforetheChristianera，weofto-dayshouldstillreceivetheirlightandseemtoseethemjustaswedo。Whenwelookuptothesky，westudyancienthistory；wedonotseethestarsastheyARE，butastheyWEREyears，centuries，evenmillenniaago。
Theinformationderivedfromtheparallaxofastarbynomeanshaltswiththedisclosureofthedistanceofthatbody。Distanceknown，thepropermotionofthestar，hithertoonlytobereckonedassomanysecondsofarc，mayreadilybetranslatedintoactualspeedofprogress；
relativebrightnessbecomesabsolutelustre，ascomparedwiththesun；andinthecaseofthedoublestarstheabsolutemassofthecomponentsmaybecomputedfromthelawsofgravitation。Itisfoundthatstarsdifferenormouslyamongthemselvesinalltheseregards。Astospeed，some，likeoursun，barelycreepthroughspace——compassingtenortwentymilesasecond，itistrue，yetevenatthatrateonlypassingthroughtheequivalentoftheirowndiameterinaday。
Attheotherextreme，amongmeasuredstars，isonethatmovestwohundredmilesasecond；yeteventhis\"flyingstar，\"asseenfromtheearth，seemstochangeitsplacebyonlyaboutthreeandahalflunardiametersinathousandyears。Inbrightness，somestarsyieldtothesun，whileotherssurpasshimasthearc-lightsurpassesacandle。Arcturus，thebrightestmeasuredstar，shinesliketwohundredsuns；andeventhisgiantorbisdimbesidethoseotherstarswhicharesodistantthattheirparallaxcannotbemeasured，yetwhichgreetoureyesatfirstmagnitude。Astoactualbulk，ofwhichapparentlustrefurnishesnoadequatetest，somestarsaresmallerthanthesun，whileothersexceedhimhundredsorperhapsthousandsoftimes。Yetoneandall，sodistantarethey，remainmeredisklikepointsoflightbeforetheutmostpowersofthemoderntelescope。
RevelationsoftheSpectroscopeAllthisseemswonderfulenough，butevengreaterthingswereinstore。In1859thespectroscopecameuponthescene，perfectedbyKirchhoffandBunsen，alonglinespointedoutbyFraunhoferalmosthalfacenturybefore。Thatmarvellousinstrument，byrevealingthetelltalelinessprinkledacrossaprismaticspectrum，disclosesthechemicalnatureandphysicalconditionofanysubstancewhoselightissubmittedtoit，tellingitsstoryequallywell，providedthelightbestrongenough，whethertheluminoussubstancebenearorfar——inthesameroomorattheconfinesofspace。
Clearlysuchaninstrumentmustproveaveritablemagicwandinthehandsoftheastronomer。
Verysooneagerastronomersallovertheworldwereputtingthespectroscopetothetest。Kirchhoffhimselfledtheway，andDonatiandFatherSecchiinItaly，HugginsandMillerinEngland，andRutherfurdinAmerica，werethechiefofhisimmediatefollowers。
Theresultsexceededthedreamsofthemostvisionary。
Attheveryoutset，in1860，itwasshownthatsuchcommonterrestrialsubstancesassodium，iron，calcium，magnesium，nickel，barium，copper，andzincexistintheformofglowingvaporsinthesun，andverysoonthestarsgaveupacorrespondingsecret。Sincethentheworkofsolarandsiderealanalysishasgoneonsteadilyinthehandsofamultitudeofworkersprominentamongwhom，inthiscountry，areProfessorYoungofPrinceton，ProfessorLangleyofWashington，andProfessorPickeringofHarvard，andmorethanhalftheknownterrestrialelementshavebeendefinitelylocatedinthesun，whilefreshdiscoveriesareinprospect。
Itistruethesunalsocontainssomeseemingelementsthatareunknownontheearth，butthisisnomatterforsurprise。Themodernchemistmakesnoclaimforhiselementsexceptthattheyhavethusfarresistedallhumaneffortstodissociatethem；itwouldbenothingstrangeifsomeofthem，whensubjectedtothecrucibleofthesun，whichisseentovaporizeiron，nickel，silicon，shouldfailtowithstandthetest。Butagain，chemistryhasbynomeansexhaustedtheresourcesoftheearth’ssupplyofrawmaterial，andthesubstancewhichsendsitsmessagefromastarmayexistundiscoveredinthedustwetreadorintheairwebreathe。Intheyear1895twonewterrestrialelementswerediscovered；butoneofthesehadforyearsbeenknowntotheastronomerasasolarandsuspectedasastellarelement，andnamedheliumbecauseofitsabundanceinthesun。Thespectroscopehadreachedoutmillionsofmilesintospaceandbroughtbackthisnewelement，andittookthechemistascoreofyearstodiscoverthathehadallalonghadsamplesofthesamesubstanceunrecognizedinhissublunarylaboratory。
Thereishardlyamorepicturesquefactthanthatintheentirehistoryofscience。
Buttheidentityinsubstanceofearthandsunandstarswasnotmoreclearlyshownthanthediversityoftheirexistingphysicalconditions。Itwasseenthatsunandstars，farfrombeingthecool，earthlike，habitablebodiesthatHerschelthoughtthemsurroundedbyglowingclouds，andprotectedfromundueheatbyotherclouds，areintruthseethingcaldronsoffieryliquid，orgasmadeviscidbycondensation，withluridenvelopesofbelchingflames。Itwassoonmadeclear，also，particularlybythestudiesofRutherfurdandofSecchi，thatstarsdifferamongthemselvesinexactconstitutionorcondition。TherearewhiteorSirianstars，whosespectrumrevelsinthelinesofhydrogen；yelloworsolarstarsoursunbeingthetype，showingvariousmetallicvapors；andsundryredstars，withbandedspectraindicativeofcarboncompounds；besidesthepurelygaseousstarsofmorerecentdiscovery，whichProfessorPickeringhadspeciallystudied。Zollner’sfamousinterpretationofthesediversities，asindicativeofvaryingstagesofcooling，hasbeencalledinquestionastotheexactsequenceitpostulates，butthegeneralpropositionthatstarsexistunderwidelyvaryingconditionsoftemperatureishardlyindispute。
Theassumptionthatdifferentstartypesmarkvaryingstagesofcoolinghasthefurthersupportofmodernphysics，whichhasbeenunabletodemonstrateanywayinwhichthesun’sradiatedenergymayberestored，orotherwisemadeperpetual，sincemeteoricimpacthasbeenshowntobe——underexistingconditions，atanyrate——inadequate。InaccordancewiththetheoryofHelmholtz，thechiefsupplyofsolarenergyisheldtobecontractionofthesolarmassitself；andplainlythismusthaveitslimits。Therefore，unlesssomemeansasyetunrecognizedisrestoringthelostenergytothestellarbodies，eachofthemmustgraduallyloseitslustre，andcometoaconditionofsolidification，seemingsterility，andfrigiddarkness。Inthecaseofourownparticularstar，accordingtotheestimateofLordKelvin，suchaculminationappearslikelytooccurwithinaperiodoffiveorsixmillionyears。
TheAstronomyoftheInvisibleButbyfarthestrongestsupportofsuchaforecastasthisisfurnishedbythosestellarbodieswhichevennowappeartohavecooledtothefinalstageofstardevelopmentandceasedtoshine。Ofthisclassexamplesinminiaturearefurnishedbytheearthandthesmallerofitscompanionplanets。Buttherearelargerbodiesofthesametypeoutinstellarspace——veritable\"darkstars\"——invisible，ofcourse，yetnowadaysclearlyrecognized。
Theopeningupofthis\"astronomyoftheinvisible\"
isanotherofthegreatachievementsofthenineteenthcentury，andagainitisBesseltowhomthehonorofdiscoveryisdue。Whiletestinghisstarsforparallax；
thatastuteobserverwasledtoinfer，fromcertainunexplainedaberrationsofmotion，thatvariousstars，Siriushimselfamongthenumber，areaccompaniedbyinvisiblecompanions，andin1840hedefinitelypredicatedtheexistenceofsuch\"darkstars。\"Thecorrectnessoftheinferencewasshowntwentyyearslater，whenAlvanClark，Jr。，theAmericanoptician，whiletestinganewlens，discoveredthecompanionofSirius，whichprovedthustobefaintlyluminous。
Sincethentheexistenceofotherandquiteinvisiblestarcompanionshasbeenprovedincontestably，notmerelybyrenewedtelescopicobservations，butbythecurioustestimonyoftheubiquitousspectroscope。
Oneofthemostsurprisingaccomplishmentsofthatinstrumentisthepowertorecordtheflightofaluminousobjectdirectlyinthelineofvision。Iftheluminousbodyapproachesswiftly，itsFraunhoferlinesareshiftedfromtheirnormalpositiontowardsthevioletendofthespectrum；ifitrecedes，thelinesshiftintheoppositedirection。Theactualmotionofstarswhosedistanceisunknownmaybemeasuredinthisway。
Butincertaincasesthelightlinesareseentooscillateonthespectrumatregularintervals。Obviouslythestarsendingsuchlightisalternatelyapproachingandreceding，andtheinferencethatitisrevolvingaboutacompanionisunavoidable。Fromthisextraordinarytesttheorbitaldistance，relativemass，andactualspeedofrevolutionoftheabsolutelyinvisiblebodymaybedetermined。Thusthespectroscope，whichdealsonlywithlight，makesparadoxicalexcursionsintotherealmoftheinvisible。Whatsecretsmaythestarshopetoconcealwhenquestionedbyaninstrumentofsuchnecromanticpower？
Butthespectroscopeisnotaloneinthisaudaciousassaultuponthestrongholdsofnature。Ithasaworthycompanionandassistantinthephotographicfilm，whoseefficientaidhasbeeninvokedbytheastronomerevenmorerecently。Pioneerworkincelestialphotographywas，indeed，donebyAragoinFranceandbytheelderDraperinAmericain1839，buttheresultsthenachievedwereonlytentative，anditwasnottillfortyyearslaterthatthemethodassumedreallyimportantproportions。In1880，Dr。HenryDraper，atHastings-on-the-Hudson，madethefirstsuccessfulphotographofanebula。Soonafter，Dr。DavidGill，attheCapeobservatory，madefinephotographsofacomet，andtheflecksofstarlightonhisplatesfirstsuggestedthepossibilitiesofthismethodinchartingtheheavens。
Sincethenstar-chartingwiththefilmhascomevirtuallytosupersedetheoldmethod。Aconcertedeffortisbeingmadebyastronomersinvariouspartsoftheworldtomakeacompletechartoftheheavens，andbeforethecloseofourcenturythisworkwillbeaccomplished，somefiftyorsixtymillionsofvisiblestarsbeingplacedonrecordwithadegreeofaccuracyhithertounapproachable。Moreover，othermillionsofstarsarebroughttolightbythenegative，whicharetoodistantordimtobevisiblewithanytelescopicpowersyetattained——afactwhichwhollydiscreditsallpreviousinferencesastothelimitsofoursiderealsystem。
Hence，notwithstandingthewonderfulinstrumentaladvancesofthenineteenthcentury，knowledgeoftheexactformandextentofouruniverseseemsmoreunattainablethanitseemedacenturyago。
TheStructureofNebulaeYetthenewinstruments，whileleavingsomuchuntold，haverevealedsomevastlyimportantsecretsofcosmicstructure。Inparticular，theyhavesetatrestthelong-standingdoubtsastotherealstructureandpositionofthemysteriousnebulae——thoselazymasses，onlytwoorthreeofthemvisibletotheunaidedeye，whichthetelescoperevealsinalmostlimitlessabundance，scatteredeverywhereamongthestars，butgroupedinparticularaboutthepolesofthestellarstreamordiskwhichwecalltheMilkyWay。
Herschel’slaterview，whichheldthatsomeatleastofthenebulaearecomposedofa\"shiningfluid，\"inprocessofcondensationtoformstars，wasgenerallyacceptedforalmosthalfacentury。Butin1844，whenLordRosse’sgreatsix-footreflector——thelargesttelescopeeveryetconstructed——wasturnedonthenebulae，itmadethishypothesisseemverydoubtful。JustasGalileo’sfirstlenshadresolvedtheMilkyWayintostars，justasHerschelhadresolvednebulaethatresistedallinstrumentsbuthisown，soLordRosse’sevengreaterreflectorresolvedothersthatwouldnotyieldtoHerschel’slargestmirror。Itseemedafairinferencethatwithsufficientpower，perhapssomedaytobeattained，allnebulaewouldyield，hencethatallareinrealitywhatHerschelhadatfirstthoughtthem——
vastlydistant\"islanduniverses，\"composedofaggregationsofstars，comparabletoourowngalacticsystem。
Buttheinferencewaswrong；forwhenthespectroscopewasfirstappliedtoanebulain1864，byDr。Huggins，itclearlyshowedthespectrumnotofdiscretestars，butofagreatmassofglowinggases，hydrogenamongothers。Moreextendedstudiesshowed，itistrue，thatsomenebulaegivethecontinuousspectrumofsolidsorliquids，butthedifferenttypesintermingleandgradeintooneanother。Also，theclosestaffinityisshownbetweennebulaeandstars。Somenebulaearefoundtocontainstars，singlyoringroups，intheiractualmidst；certaincondensed\"planetary\"nebulaearescarcelytobedistinguishedfromstarsofthegaseoustype；andrecentlythephotographicfilmhasshownthepresenceofnebulousmatteraboutstarsthattotelescopicvisiondifferinnorespectfromthegeneralityoftheirfellowsinthegalaxy。ThefamiliarstarsofthePleiadescluster，forexample，appearonthenegativeimmersedinahazybluroflight。Allinall，theaccumulatedimpressionsofthephotographicfilmrevealaprodigalityofnebulousmatterinthestellarsystemnothithertoevenconjectured。
Andso，ofcourse，allquestionof\"islanduniverses\"
vanishes，andthenebulaearerelegatedtotheirtruepositionascomponentpartsoftheonestellarsystem——theoneuniverse——thatisopentopresenthumaninspection。
Andthesevastcloudsofworld-stuffhavebeenfoundbyProfessorKeeler，oftheLickobservatory，tobefloatingthroughspaceatthestarlikespeedoffromtentothirty-eightmilespersecond。
Thelinkingofnebulaewithstars，soclearlyevidencedbyallthesemodernobservations，is，afterall，onlythescientificcorroborationofwhattheelderHerschel’slatertheoriesaffirmed。Butthenebulaehaveotheraffinitiesnotuntilrecentlysuspected；forthespectraofsomeofthemarepracticallyidenticalwiththespectraofcertaincomets。Theconclusionseemswarrantedthatcometsareinpointoffactminornebulaethataredrawnintooursystem；or，puttingitotherwise，thatthetelescopicnebulaearesimplygiganticdistantcomets。
Lockyer’sMeteoricHypothesisFollowingupthesurprisingclewsthussuggested，SirNormanLockyer，ofLondon，hasinrecentyearselaboratedwhatisperhapsthemostcomprehensivecosmogonicguessthathaseverbeenattempted。Histheory，knownasthe\"meteorichypothesis，\"probablybearsthesamerelationtothespeculativethoughtofourtimethatthenebularhypothesisofLaplaceboretothatoftheeighteenthcentury。Outlinedinafewwords，itisanattempttoexplainallthemajorphenomenaoftheuniverseasdue，directlyorindirectly，tothegravitationalimpactofsuchmeteoricparticles，orspecksofcosmicdust，ascometsarecomposedof。Nebulaearevastcometaryclouds，withparticlesmoreorlesswidelyseparated，givingoffgasesthroughmeteoriccollisions，internalorexternal，andperhapsglowingalsowithelectricalorphosphorescentlight。Gravityeventuallybringsthenebularparticlesintocloseraggregations，andincreasedcollisionsfinallyvaporizetheentiremass，formingplanetarynebulaeandgaseousstars。
Continuedcondensationmaymakethestellarmasshotterandmoreluminousforatime，buteventuallyleadstoitsliquefaction，andultimateconsolidation——
theaforetimenebulaebecomingintheendadarkorplanetarystar。
TheexactcorrelationwhichLockyerattemptstopointoutbetweensuccessivestagesofmeteoriccondensationandthevarioustypesofobservedstellarbodiesdoesnotmeetwithunanimousacceptance。Mr。
Ranyard，forexample，suggeststhatthevisiblenebulaemaynotbenascentstars，butemanationsfromstars，andthatthetruepre-stellarnebulaeareinvisibleuntilcondensedtostellarproportions。Butsuchdetailsaside，thebroadgeneralhypothesisthatallthebodiesoftheuniverseare，sotospeak，ofasinglespecies——
thatnebulaeincludingcomets，starsofalltypes，andplanets，arebutvaryingstagesinthelifehistoryofasingleraceortypeofcosmicorganisms——isacceptedbythedominantthoughtofourtimeashavingthehighestwarrantofscientificprobability。
Allthis，clearly，isbutanamplificationofthatnebularhypothesiswhich，longbeforethespectroscopegaveuswarranttoaccuratelyjudgeoursiderealneighbors，hadboldlyimaginedthedevelopmentofstarsoutofnebulaeandofplanetsoutofstars。ButLockyer’shypothesisdoesnotstopwiththis。Havingtracedthedevelopmentalprocessfromthenebulartothedarkstar，itseesnocausetoabandonthisdarkstartoitsfatebyassuming，astheoriginalspeculationassumed，thatthisisaculminatingandfinalstageofcosmicexistence。
Forthedarkstar，thoughitsmolecularactivitieshavecometorelativestabilityandimpotence，stillretainstheenormouspotentialitiesofmolarmotion；
andclearly，wheremotionis，stasisisnot。Soonerorlater，initsceaselessflightthroughspace，thedarkstarmustcollidewithsomeotherstellarbody，asDr。
Crollimaginesofthedarkbodieswhichhis\"pre-nebulartheory\"postulates。Suchcollisionmaybelongdelayed；thedarkstarmaybedrawnincomet-likecircuitaboutthousandsofotherstellarmasses，andbehurtledonthousandsofdiverseparabolicorellipticalorbits，beforeitchancestocollide——butthatmattersnot:\"billionsaretheunitsinthearithmeticofeternity，\"
andsoonerorlater，wecanhardlydoubt，acollisionmustoccur。Thenwithoutquestionthemutualimpactmustshatterbothcollidingbodiesintovapor，orvaporcombinedwithmeteoricfragments；inshort，intoaveritablenebula，thematrixoffutureworlds。
Thusthedarkstar，whichisthelasttermofoneseriesofcosmicchanges，becomesthefirsttermofanotherseries——atonceapost-nebularandapre-nebularcondition；
andthenebularhypothesis，thusamplified，ceasestobeamerelinearscale，andisroundedouttoconnoteanunendingseriesofcosmiccycles，morenearlysatisfyingtheimagination。
Inthisextendedview，nebulaeandluminousstarsarebuttheinfantileandadolescentstagesofthelifehistoryofthecosmicindividual；thedarkstar，itsadultstage，ortimeoftruevirility。Orwemaythinkoftheshrunkendarkstarasthegerm-cell，thepollen-grain，ofthecosmicorganism。Reducedinsize，asbecomesagerm-cell，toamerefractionofthenebularbodyfromwhichitsprang，ityetretainswithinitsseeminglynon-
vitalbodyallthepotentialitiesoftheoriginalorganism，andrequiresonlytoblendwithafellow-celltobringanewgenerationintobeing。Thusmaythecosmicrace，whoseaggregatecensusmakesupthestellaruniverse，beperpetuated——individualsolarsystems，suchasours，beingborn，andgrowingold，anddyingtoliveagainintheirdescendants，whiletheuniverseasawholemaintainsitsunifiedintegritythroughoutalltheseinternalmutations——passingon，itmaybe，byinfinitesimalstages，toaculminationhopelesslybeyondhumancomprehension。
III。THENEWSCIENCEOFPALEONTOLOGY
WILLIAMSMITHANDFOSSILSHELLS
EversinceLeonardodaVincifirstrecognizedthetruecharacteroffossils，therehadbeenhereandthereamanwhorealizedthattheearth’srockycrustisonegiganticmausoleum。Hereandthereadilettantehadfilledhiscabinetswithrelicsfromthismonstercrypt；hereandthereaphilosopherhadponderedoverthem——questioningwhetherperchancetheyhadoncebeenalive，orwhethertheywerenotmereabortivesouvenirsofthattimewhenthefertilematrixoftheearthwassupposedtohave\"teemedatabirthInnumerouslivingcreatures，perfectforms，Limbedandfullgrown。\"
Somefewofthesephilosophers——asRobertHookeandStenointheseventeenthcentury，andMoro，Leibnitz，Buffon，Whitehurst，Werner，Hutton，andothersintheeighteenth——hadvaguelyconceivedtheimportanceoffossilsasrecordsoftheearth’sancienthistory，butthewisestofthemnomoresuspectedthefullimportofthestorywrittenintherocksthantheaveragestrollerinamodernmuseumsuspectsthemeaningofthehieroglyphsonthecaseofamummy。
Itwasnotthattherudimentsofthisstoryaresoveryhardtodecipher——thoughintruththeyarehardenough——butratherthatthemenwhomadetheattempthadallalongviewedthesubjectthroughanatmosphereofpreconception，whichgaveadistortedimage。Beforethisimagecouldbecorrecteditwasnecessarythatamanshouldappearwhocouldseewithoutprejudice，andapplysoundcommon-sensetowhathesaw。Andsuchamandidappeartowardsthecloseofthecentury，inthepersonofWilliamSmith，theEnglishsurveyor。Hewasaself-taughtman，andperhapsthemoreindependentforthat，andhehadthegift，besideshissharpeyesandreceptivemind，ofamosttenaciousmemory。Byexercisingthesefaculties，rareastheyarehomely，heledthewaytoasciencewhichwasdestined，initslaterdevelopments，toshakethestructureofestablishedthoughttoitsfoundations。
LittleenoughdidWilliamSmithsuspect，however，thatanysuchdireconsequencesweretocomeofhisactwhenhefirstbegannoticingthefossilshellsthathereandtherearetobefoundinthestratifiedrocksandsoilsoftheregionsoverwhichhissurveyor’sdutiesledhim。Nor，indeed，wasthereanythingofsuchapparentrevolutionarycharacterinthefactswhichheunearthed；yetintheirimplicationsthesefactswerethemostdisconcertingofanythathadbeenrevealedsincethedaysofCopernicusandGalileo。Initsbaldessence，Smith’sdiscoverywassimplythis:thatthefossilsintherocks，insteadofbeingscatteredhaphazard，arearrangedinregularsystems，sothatanygivenstratumofrockislabelledbyitsfossilpopulation；
andthattheorderofsuccessionofsuchgroupsoffossilsisalwaysthesameinanyverticalseriesofstratainwhichtheyoccur。Thatistosay，iffossilAunderliesfossilBinanygivenregion，itneveroverliesitinanyotherseries；thoughakindoffossilsfoundinonesetofstratamaybequiteomittedinanother。Moreover，afossiloncehavingdisappearedneverreappearsinanylaterstratum。
FromthesenovelfactsSmithdrewthecommonsenseinferencethattheearthhadhadsuccessivepopulationsofcreatures，eachofwhichinitsturnhadbecomeextinct。Hepartiallyverifiedthisinferencebycomparingthefossilshellswithexistingspeciesofsimilarorders，andfoundthatsuchasoccurinolderstrataoftherockshadnocounterpartsamonglivingspecies。But，onthewhole，beingeminentlyapracticalman，Smithtroubledhimselfbutlittleabouttheinferencesthatmightbedrawnfromhisfacts。HewaschieflyconcernedinusingthekeyhehaddiscoveredasanaidtotheconstructionofthefirstgeologicalmapofEnglandeverattempted，andhelefttootherstheuntanglingofanysnarlsofthoughtthatmightseemtoarisefromhisdiscoveryofthesuccessionofvaryingformsoflifeontheglobe。
Hedisseminatedhisviewsfarandwide，however，inthecourseofhisjourneyings——quitedisregardingthefactthatperipateticswentoutoffashionwhentheprinting-presscamein——andbythebeginningofthenineteenthcenturyhehadbeguntohaveafollowingamongthegeologistsofEngland。Itmustnotforamomentbesupposed，however，thathiscontentionregardingthesuccessionofstratametwithimmediateorgeneralacceptance。Onthecontrary，itwasmostbitterlyantagonized。Foralonggenerationafterthediscoverywasmade，thegeneralityofmen，proneasalwaystostrainatgnatsandswallowcamels，preferredtobelievethatthefossils，insteadofbeingdepositedinsuccessiveages，hadbeensweptallatonceintotheirpresentpositionsbythecurrentofamightyflood——andthatflood，needlesstosay，theNoachiandeluge。Justhowthenumberlesssuccessivestratacouldhavebeenlaiddowninorderlysequencetothedepthofseveralmilesinonesuchfellcataclysmwasindeedpuzzling，especiallyafteritcametobeadmittedthattheheaviestfossilswerenotfoundalwaysatthebottom；buttodoubtthatthishadbeendoneinsomewaywasrankheresyintheearlydaysofthenineteenthcentury。
CUVIERANDFOSSILVERTEBRATES
Butoncediscovered，WilliamSmith’suniquefactsastothesuccessionofformsintherockswouldnotdown。Therewasonemostvitalpoint，however，regardingwhichtheinferencesthatseemtofollowfromthesefactsneededverification——thequestion，namely，whetherthedisappearanceofafaunafromtheregisterintherocksreallyimpliestheextinctionofthatfauna。
Everythingreallydependedupontheanswertothatquestion，andnonebutanaccomplishednaturalistcouldansweritwithauthority。Fortunately，themostauthoritativenaturalistofthetime，GeorgeCuvier，tookthequestioninhand——not，indeed，withtheideaofverifyinganysuggestionofSmith’s，butinthecourseofhisownoriginalstudies——attheverybeginningofthecentury，whenSmith’sviewswereattractinggeneralattention。
CuvierandSmithwereexactcontemporaries，bothmenhavingbeenbornin1769，that\"fertileyear\"
whichgavetheworldalsoChateaubriand，VonHumboldt，Wellington，andNapoleon。ButtheFrenchnaturalistwasofverydifferentantecedentsfromtheEnglishsurveyor。Hewasbrilliantlyeducated，hadearlygainedrecognitionasascientist，andwhileyetayoungmanhadcometobeknownastheforemostcomparativeanatomistofhistime。Itwastheanatomicalstudiesthatledhimintotherealmoffossils。Somebonesdugoutoftherocksbyworkmeninaquarrywerebroughttohisnotice，andatoncehistrainedeyetoldhimthattheyweredifferentfromanythinghehadseenbefore。Hithertosuchbones，whennotentirelyignored，hadbeenforthemostpartascribedtogiantsofformerdays，oreventofallenangels。Cuviersoonshowedthatneithergiantsnorangelswereinquestion，butelephantsofanunrecognizedspecies。Continuinghisstudies，particularlywithmaterialgatheredfromgypsumbedsnearParis，hehadaccumulated，bythebeginningofthenineteenthcentury，bonesofabouttwenty-fivespeciesofanimalsthathebelievedtobedifferentfromanynowlivingontheglobe。
Thefameofthesestudieswentabroad，andpresentlyfossilbonespouredinfromallsides，andCuvier’sconvictionthatextinctformsofanimalsarerepresentedamongthefossilswassustainedbytheevidenceofmanystrangeandanomalousforms，someofthemofgiganticsize。In1816thefamousOssementsFossiles，describingthesenovelobjects，waspublished，andvertebratepaleontologybecameascience。Amongotherthingsofgreatpopularinterestthebookcontainedthefirstauthoritativedescriptionofthehairyelephant，namedbyCuvierthemammoth，theremainsofwhichbadbeenfoundembeddedinamassoficeinSiberiain1802，sowonderfullypreservedthatthedogsoftheTungusianfishermenactuallyateitsflesh。BonesofthesamespecieshadbeenfoundinSiberiaseveralyearsbeforebythenaturalistPallas，whohadalsofoundthecarcassofarhinocerosthere，frozeninamud-bank；butnoonethensuspectedthattheseweremembersofanextinctpopulation——theyweresupposedtobemerelytransportedrelicsoftheflood。
Cuvier，ontheotherhand，assertedthattheseandtheothercreatureshedescribedhadlivedanddiedintheregionwheretheirremainswerefound，andthatmostofthemhavenolivingrepresentativesupontheglobe。
This，tobesure，wasnothingmorethanWilliamSmithhadtriedallalongtoestablishregardinglowerformsoflife；butfleshandbloodmonstersappealtotheimaginationinawayquitebeyondthepowerofmereshells；
sotheannouncementofCuvier’sdiscoveriesarousedtheinterestoftheentireworld，andtheOssementsFossileswasaccordedapopularreceptionseldomgivenaworkoftechnicalscience——areceptioninwhichtheenthusiasticapprovalofprogressivegeologistswasmingledwiththebitterprotestsoftheconservatives。
\"Naturalistscertainlyhaveneitherexploredallthecontinents，\"saidCuvier，\"nordotheyasyetevenknowallthequadrupedsofthosepartswhichhavebeenexplored。
Newspeciesofthisclassarediscoveredfromtimetotime；andthosewhohavenotexaminedwithattentionallthecircumstancesbelongingtothesediscoveriesmayallegealsothattheunknownquadrupeds，whosefossilboneshavebeenfoundinthestrataoftheearth，havehithertoremainedconcealedinsomeislandsnotyetdiscoveredbynavigators，orinsomeofthevastdesertswhichoccupythemiddleofAfrica，Asia，thetwoAmericas，andNewHolland。
\"Butifwecarefullyattendtothekindofquadrupedsthathavebeenrecentlydiscovered，andtothecircumstancesoftheirdiscovery，weshalleasilyperceivethatthereisverylittlechanceindeedofoureverfindingalivethosewhichhaveonlybeenseeninafossilstate。
\"Islandsofmoderatesize，andataconsiderabledistancefromthelargecontinents，haveveryfewquadrupeds。
Thesemusthavebeencarriedtothemfromothercountries。CookandBougainvillefoundnootherquadrupedsbesideshogsanddogsintheSouthSeaIslands；andthelargestquadrupedoftheWestIndiaIslands，whenfirstdiscovered，wastheagouti，aspeciesofthecavy，ananimalapparentlybetweentheratandtherabbit。
\"Itistruethatthegreatcontinents，asAsia，Africa，thetwoAmericas，andNewHolland，havelargequadrupeds，and，generallyspeaking，containspeciescommontoeach；insomuch，thatupondiscoveringcountrieswhichareisolatedfromtherestoftheworld，theanimalstheycontainoftheclassofquadrupedwerefoundentirelydifferentfromthosewhichexistedinothercountries。Thus，whentheSpaniardsfirstpenetratedintoSouthAmerica，theydidnotfindittocontainasinglequadrupedexactlythesamewiththoseofEurope，Asia，andAfrica。Thepuma，thejaguar，thetapir，thecapybara，thellama，orglama，andvicuna，andthewholetribeofsapajous，weretothementirelynewanimals，ofwhichtheyhadnotthesmallestidea……
\"Iftherestillremainedanygreatcontinenttobediscovered，wemightperhapsexpecttobemadeacquaintedwithnewspeciesoflargequadrupeds，amongwhichsomemightbefoundmoreorlesssimilartothoseofwhichwefindtheexuviaeinthebowelsoftheearth。
Butitismerelysufficienttoglancetheeyeoverthemapsoftheworldandobservetheinnumerabledirectionsinwhichnavigatorshavetraversedtheocean，inordertobesatisfiedthattheredoesnotremainanylargelandtobediscovered，unlessitmaybesituatedtowardstheAntarcticPole，whereeternalicenecessarilyforbidstheexistenceofanimallife。\"[1]
CuvierthenpointsoutthattheancientswerewellacquaintedwithpracticallyalltheanimalsonthecontinentsofEurope，Asia，andAfricanowknowntoscientists。Hefindslittlegrounds，therefore，forbeliefinthetheorythatatonetimethereweremonstrousanimalsontheearthwhichitwasnecessarytodestroyinorderthatthepresentfaunaandmenmightflourish。
Afterreviewingthesetheoriesandbeliefsindetail，hetakesuphisInquiryRespectingtheFabulousAnimalsoftheAncients。\"Itiseasy，\"hesays，\"toreplytotheforegoingobjections，byexaminingthedescriptionsthatareleftusbytheancientsofthoseunknownanimals，andbyinquiringintotheirorigins。Nowthatthegreaternumberoftheseanimalshaveanorigin，thedescriptionsgivenofthembearthemostunequivocalmarks；asinalmostallofthemweseemerelythedifferentpartsofknownanimalsunitedbyanunbridledimagination，andincontradictiontoeveryestablishedlawofnature。\"[2]
Havingshownhowthefabulousmonstersofancienttimesandofforeignnations，suchastheChinese，weresimplyproductsoftheimagination，havingnoprototypesinnature，Cuviertakesuptheconsiderationofthedifficultyofdistinguishingthefossilbonesofquadrupeds。
WeshallhaveoccasiontoreverttothispartofCuvier’spaperinanotherconnection。Hereitsufficestopassatoncetothefinalconclusionthatthefossilbonesinquestionaretheremainsofanextinctfauna，thelikeofwhichhasnopresent-dayrepresentationontheearth。Whateveritsimplications，thisconclusionnowseemedtoCuviertobefullyestablished。
InEnglandtheinterestthusarousedwassenttofever-heatin1821bythediscoveryofabundantbedsoffossilbonesinthestalagmite-coveredfloorofacaveatKirkdale，YorkshirewhichwenttoshowthatEngland，too，hadoncehadhershareofgiganticbeasts。
Dr。Buckland，theincumbentofthechairofgeologyatOxford，andthemostauthoritativeEnglishgeologistofhisday，tookthesefindsinhandandshowedthatthebonesbelongedtoanumberofspecies，includingsuchalienformsaselephants，rhinoceroses，hippopotami，andhyenas。HemaintainedthatallofthesecreatureshadactuallylivedinBritain，andthatthecavesinwhichtheirboneswerefoundhadbeenthedensofhyenas。
Theclaimwashotlydisputed，asamatterofcourse。
Aslateas1827bookswerepublisheddenouncingBuckland，doctorofdivinitythoughhewas，asonewhohadjoinedinan\"unhallowedcause，\"andreiteratingtheoldcrythatthefossilswereonlyremainsoftropicalspecieswashedthitherbythedeluge。Thattheywerefoundinsolidrocksorincavesofferednodifficulty，atleastnottothefertileimaginationofGranvillePenn，theleaderoftheconservatives，whoclungtotheoldideaofWoodwardandCattcutthatthedelugehaddissolvedtheentirecrustoftheearthtoapaste，intowhichtherelicsnowcalledfossilshadsettled。Thecaves，saidMr。Penn，aremerelytheresultofgasesgivenoffbythecarcassesduringdecomposition——
greatair-bubbles，sotospeak，inthepastymass，becomingcavernswhenthewatersrecededandthepastehardenedtorockyconsistency。
Buttheseandsuch-likefancifulviewsweredoomedeveninthedayoftheirutterance。Alreadyin1823
othergiganticcreatures，christenedichthyosaurusandplesiosaurusbyConybeare，hadbeenfoundindeeperstrataofBritishrocks；andthese，aswellasothermonsterswhoseremainswereunearthedinvariouspartsoftheworld，boresuchstrangeformsthateventhemostscepticalcouldscarcelyhopetofindtheircounterpartsamonglivingcreatures。Cuvier’scontentionthatallthelargervertebratesoftheexistingageareknowntonaturalistswasborneoutbyrecentexplorations，andthereseemednorefugefromtheconclusionthatthefossilrecordstellofpopulationsactuallyextinct。
Butifthiswereadmitted，thenSmith’sviewthattherehavebeensuccessiverotationsofpopulationcouldnolongerbedenied。Norcoulditbeindoubtthatthesuccessivefaunas，whoseindividualremainshavebeenpreservedinmyriads，representingextinctspeciesbythousandsandtensofthousands，musthaverequiredvastperiodsoftimefortheproductionandgrowthoftheircountlessgenerations。
Asthesefactscametobegenerallyknown，andasitcametobeunderstoodinadditionthattheverymatrixoftherockinwhichfossilsareimbeddedisinmanycasesonegiganticfossil，composedoftheremainsofmicroscopicformsoflife，common-sense，which，afterall，isthefinaltribunal，cametotheaidofbelaboredscience。Itwasconcededthattheonlytenableinterpretationoftherecordintherocksisthatnumerouspopulationsofcreatures，distinctfromoneanotherandfrompresentforms，haverisenandpassedaway；andthatthegeologicagesinwhichthesecreatureslivedwereofinconceivablelength。Therankandfilecamethus，withtheaidoffossilrecords，torealizetheimportofanideawhichJamesHutton，andhereandthereanotherthinker，hadconceivedwiththeswiftintuitionofgeniuslongbeforethescienceofpaleontologycameintoexistence。TheHuttonianpropositionthattimeislonghadbeenabundantlyestablished，andbyaboutthecloseofthefirstthirdofthelastcenturygeologistshadbeguntospeakof\"ages\"and\"untoldaeonsoftime\"withafamiliaritywhichtheirpredecessorshadreservedfordaysanddecades。
CHARLESLYELLCOMBATSCATASTROPHISM
Andnowanewquestionpressedforsolution。Iftheearthhasbeeninhabitedbysuccessivepopulationsofbeingsnowextinct，howhaveallthesecreaturesbeendestroyed？Thatquestion，however，seemedtopresentnodifficulties。Itwasansweredoutofhandbytheapplicationofanoldidea。Alldownthecenturies，whatevertheirvaryingphasesofcosmogonicthought，therehadbeeneverpresenttheideathatpasttimeswerenotasrecenttimes；thatinremoteepochstheearthhadbeenthesceneofawfulcatastrophesthathavenoparallelin\"thesedegeneratedays。\"Naturallyenough，thisthought，embalmedineverycosmogonicspeculationofwhateverorigin，wasappealedtoinexplanationofthedestructionofthesehithertounimaginedhosts，whichnow，thankstoscience，rosefromtheirabysmalslumberasincontestable，butalsoassilentandasthought-provocative，asSphinxorpyramid。
Theseancienthosts，itwassaid，havebeenexterminatedatintervalsofoddmillionsofyearsbytherecurrenceofcatastrophesofwhichtheMosaicdelugeisthelatest，butperhapsnotthelast。
Thisexplanationhadfullestwarrantofscientificauthority。
CuvierhadprefacedhisclassicalworkwithaspeculativedisquisitionwhoseverytitleDiscourssurlesRevolutionsduGlobeisominousofcatastrophism，andwhosetextfullysustainstheaugury。
AndBuckland，Cuvier’sforemostfolloweracrosstheChannel，hadgoneevenbeyondthemaster，namingtheworkinwhichhedescribedtheKirkdalefossils，ReliquiaeDiluvianae，orProofsofaUniversalDeluge。
Boththeseauthoritiessupposedthecreatureswhoseremainstheystudiedtohaveperishedsuddenlyinthemightyfloodwhoseawfulcurrent，astheysupposed，gougedoutthemodernvalleysandhurledgreatblocksofgranitebroadcastovertheland。Andtheyinvokedsimilarfloodsfortheexterminationofpreviouspopulations。
Itistruethesescientificcitationshadmetwithonlyqualifiedapprovalatthetimeoftheirutterance，becausethentheconservativemajorityofmankinddidnotconcedethattherehadbeenapluralityofpopulationsorrevolutions；butnowthatthebeliefinpastgeologicageshadceasedtobeaheresy，therecurringcatastrophesofthegreatpaleontologistswereacceptedwithacclaim。Forthemomentscienceandtraditionwereatone，andtherewasatrucetocontroversy，exceptindeedinthoseoutlyingskirmish-linesofthoughtwhithernewsfromheadquartersdoesnotpermeatetillithasbecomeancienthistoryatitssource。
Thetruce，however，wasnotforlong。Hardlyhadcontemporarythoughtbeguntoadjustitselftotheconceptionofpastagesofincomprehensibleextent，eachterminatedbyacatastropheoftheNoachiantype，whenamanappearedwhomadetheutterlybewilderingassertionthatthegeologicalrecord，insteadofprovingnumerouscatastrophicrevolutionsintheearth’spasthistory，givesnowarranttothepretensionsofanyuniversalcatastrophewhatever，nearorremote。
ThisiconoclastwasCharlesLyell，theScotchman，whowassoontobefamousasthegreatestgeologistofhistime。AsayoungmanhehadbecomeimbuedwiththeforceoftheHuttonianproposition，thatpresentcausesareonewiththosethatproducedthepastchangesoftheglobe，andhecarriedthatideatowhatheconceivedtobeitslogicalconclusion。Tohismindthisexcludedthethoughtofcatastrophicchangesineitherinorganicororganicworlds。
Buttodenycatastrophismwastosuggestarevolutionincurrentthought。Needlesstosay，suchrevolutioncouldnotbeeffectedwithoutalongcontest。Forascoreofyearsthematterwasarguedproandcon。，oftenwithmostunscientificardor。Amereoutlineofthecontroversywouldfillavolume；yettheessentialfactswithwhichLyellatlastestablishedhisproposition，initsbearingsontheorganicworld，maybeepitomizedinafewwords。Theevidencewhichseemstotellofpastrevolutionsistheapparentlysuddenchangeoffossilsfromonestratumtoanotheroftherocks。ButLyellshowedthatthischangeisnotalwayscomplete。
Somespeciesliveonfromoneallegedepochintothenext。Bynomeansallthecontemporariesofthemammothareextinct，andnumerousmarineformsvastlymoreancientstillhavelivingrepresentatives。
Moreover，theblanksbetweenstratainanyparticularverticalseriesareamplyfilledinwithrecordsintheformofthickstratainsomegeographicallydistantseries。Forexample，insomeregionsSilurianrocksaredirectlyoverlaidbythecoalmeasures；butelsewherethissuddenbreakisfilledinwiththeDevonianrocksthattellofagreat\"ageoffishes。\"Socommonlyarebreaksinthestratainoneregionfilledupinanotherthatweareforcedtoconcludethattherecordshownbyanysingleverticalseriesisofbutlocalsignificance——
telling，perhaps，ofatimewhenthatparticularsea-bedoscillatedabovethewater-line，andsoceasedtoreceivesedimentuntilsomefutureagewhenithadoscillatedbackagain。Butifthisbetherealsignificanceoftheseeminglysuddenchangefromstratumtostratum，thenthewholecaseforcatastrophismishopelesslylost；
forsuchbreaksinthestratafurnishtheonlysuggestiongeologycanofferofsuddenandcatastrophicchangesofwideextent。
LetusseehowLyellelaboratestheseideas，particularlywithreferencetotherotationofspecies。[2]
\"Ihavededucedasacorollary，\"hesays，\"thatthespeciesexistingatanyparticularperiodmust，inthecourseofages，becomeextinct，oneaftertheother。
’Theymustdieout，’toborrowanemphaticexpressionfromBuffon，’becauseTimefightsagainstthem。’IftheviewswhichIhavetakenarejust，therewillbenodifficultyinexplainingwhythehabitationsofsomanyspeciesarenowrestrainedwithinexceedingnarrowlimits。Everylocalrevolutiontendstocircumscribetherangeofsomespecies，whileitenlargesthatofothers；andifweareledtoinferthatnewspeciesoriginateinonespotonly，eachmustrequiretimetodiffuseitselfoverawidearea。Itwillfollow，therefore，fromtheadoptionofourhypothesisthattherecentoriginofsomespeciesandthehighantiquityofothersareequallyconsistentwiththegeneralfactoftheirlimiteddistribution，somebeinglocalbecausetheyhavenotexistedlongenoughtoadmitoftheirwidedissemination；
others，becausecircumstancesintheanimateorinanimateworldhaveoccurredtorestricttherangewithinwhichtheymayoncehaveobtained……
\"Ifthereadershouldinfer，fromthefactslaidbeforehim，thatthesuccessiveextinctionofanimalsandplantsmaybepartoftheconstantandregularcourseofnature，hewillnaturallyinquirewhetherthereareanymeansprovidedfortherepairoftheselosses？Isitpossibleasapartoftheeconomyofoursystemthatthehabitableglobeshouldtoacertainextentbecomedepopulated，bothintheoceanandontheland，orthatthevarietyofspeciesshoulddiminishuntilsomeneweraarriveswhenanewandextraordinaryeffortofcreativeenergyistobedisplayed？Orisitpossiblethatnewspeciescanbecalledintobeingfromtimetotime，andyetthatsoastonishingaphenomenoncanescapethenaturalist？
\"Inthefirstplace，itisobviouslymoreeasytoprovethataspeciesoncenumerouslyrepresentedinagivendistricthasceasedtobethanthatsomeotherwhichdidnotpre-existhadmadeitsappearance——assumingalways，forreasonsbeforestated，thatsinglestocksonlyofeachanimalandplantareoriginallycreated，andthatindividualsofnewspeciesdidnotsuddenlystartupinmanydifferentplacesatonce。
\"Soimperfecthasthescienceofnaturalhistoryremaineddowntoourowntimesthat，withinthememoryofpersonsnowliving，thenumbersofknownanimalsandplantshavedoubled，orevenquadrupled，inmanyclasses。Newandoftenconspicuousspeciesareannuallydiscoveredinpartsoftheoldcontinentlonginhabitedbythemostcivilizednations。Conscious，therefore，ofthelimitedextentofourinformation，wealwaysinfer，whensuchdiscoveriesaremade，thatthebeingsinquestionbadpreviouslyeludedourresearch，orhadatleastexistedelsewhere，andonlymigratedatarecentperiodintotheterritorieswherewenowfindthem。
\"Whatkindofproofs，therefore，couldwereasonablyexpecttofindoftheoriginataparticularperiodofanewspecies？
\"Perhaps，itmaybesaidinreply，thatwithinthelasttwoorthreecenturiessomeforesttreeornewquadrupedmighthavebeenobservedtoappearsuddenlyinthosepartsofEnglandorFrancewhichhadbeenmostthoroughlyinvestigated——thatnaturalistsmighthavebeenabletoshowthatnosuchbeinginhabitedanyotherregionoftheglobe，andthattherewasnotraditionofanythingsimilarhavingbeenobservedinthedistrictwhereithadmadeitsappearance。
\"Now，althoughthisobjectionmayseemplausible，yetitsforcewillbefoundtodependentirelyontherateoffluctuationwhichwesupposetoprevailintheanimalworld，andontheproportionswhichsuchconspicuoussubjectsoftheanimalandvegetablekingdomsbeartothosewhicharelessknownandescapeourobservation。Thereareperhapsmorethanamillionspeciesofplantsandanimals，exclusiveofthemicroscopicandinfusoryanimalcules，nowinhabitingtheterraqueousglobe，sothatifonlyoneoftheseweretobecomeextinctannually，andonenewoneweretobeeveryyearcalledintobeing，muchmorethanamillionofyearsmightberequiredtobringaboutacompleterevolutionoforganiclife。
\"Iamnothazardingatpresentanyhypothesisastotheprobablerateofchange，butnonewilldenythatwhentheannualbirthandtheannualdeathofonespeciesontheglobeisproposedasamerespeculation，this，atleast，istoimaginenoslightdegreeofinstabilityintheanimatecreation。Ifwedividethesurfaceoftheearthintotwentyregionsofequalarea，oneofthesemightcomprehendaspaceoflandandwateraboutequalindimensionstoEurope，andmightcontainatwentiethpartofthemillionofspecieswhichmaybeassumedtoexistintheanimalkingdom。Inthisregiononespeciesonlycould，accordingtotherateofmortalitybeforeassumed，perishintwentyyears，oronlyfiveoutoffiftythousandinthecourseofacentury。Butasaconsiderableportionofthewholeworldbelongstotheaquaticclasses，withwhichwehaveaveryimperfectacquaintance，wemustexcludethemfromourconsideration，and，iftheyconstitutehalfoftheentirenumber，thenonespeciesonlymightbelostinfortyyearsamongtheterrestrialtribes。
Nowthemammalia，whetherterrestrialoraquatic，bearsosmallaproportiontootherclassesofanimals，formingless，perhaps，thanathousandthpartofawhole，that，ifthelongevityofspeciesinthedifferentorderswereequal，avastperiodmustelapsebeforeitwouldcometotheturnofthisconspicuousclasstoloseoneoftheirnumber。Ifonespeciesonlyofthewholeanimalkingdomdiedoutinfortyyears，nomorethanonemammifermightdisappearinfortythousandyears，inaregionofthedimensionsofEurope。
\"Itiseasy，therefore，toseethatinasmallportionofsuchanarea，incountries，forexample，ofthesizeofEnglandandFrance，periodsofmuchgreaterdurationmustelapsebeforeitwouldbepossibletoauthenticatethefirstappearanceofoneofthelargerplantsoranimals，assumingtheannualbirthanddeathofonespeciestobetherateofvicissitudeintheanimalcreationthroughouttheworld。\"[3]
Inaword，then，saidLyell，itbecomesclearthatthenumberlessspeciesthathavebeenexterminatedinthepasthavediedoutonebyone，justasindividualsofaspeciesdie，notinvastshoals；ifwholepopulationshavepassedaway，ithasbeennotbyinstantaneousextermination，butbytheeliminationofaspeciesnowhere，nowthere，muchasonegenerationsucceedsanotherinthelifehistoryofanysinglespecies。Thecauseswhichhavebroughtaboutsuchgradualexterminations，andinthelonglapseofageshaveresultedinrotationsofpopulation，arethesamenaturalcausesthatarestillinoperation。Specieshavediedoutinthepastastheyaredyingoutinthepresent，underinfluenceofchangedsurroundings，suchasalteredclimate，orthemigrationintotheirterritoryofmoremasterfulspecies。Pastandpresentcausesareone——naturallawischangelessandeternal。
SuchwastheessenceoftheHuttoniandoctrine，whichLyelladoptedandextended，andwithwhichhisnamewillalwaysbeassociated。Largelythroughhisefforts，thoughofcoursenotwithouttheaidofmanyotherworkersafteratime，thisidea——thedoctrineofuniformitarianism，itcametobecalled——becametheaccepteddogmaofthegeologicworldnotlongafterthemiddleofthenineteenthcentury。Thecatastrophists，afterclingingmadlytotheirphantomforageneration，atlastcapitulatedwithoutterms:theoldheresybecametheneworthodoxy，andthewaywaspavedforafreshcontroversy。
THEORIGINOFSPECIES
Thefreshcontroversyfollowedquiteasamatterofcourse。Fortheideaofcatastrophismhadnotconcernedthedestructionofspeciesmerely，buttheirintroductionaswell。Ifwholefaunashadbeenextirpatedsuddenly，newfaunashadpresumablybeenintroducedwithequalsuddennessbyspecialcreation；
butifspeciesdieoutgradually，theintroductionofnewspeciesmaybepresumedtobecorrespondinglygradual。
Thenmaynotthenewspeciesofalatergeologicalepochbethemodifiedlinealdescendantsoftheextinctpopulationofanearlierepoch？
Theideathatsuchmightbethecasewasnotnew。
Ithadbeensuggestedwhenfossilsfirstbegantoattractconspicuousattention；andsuchsagaciousthinkersasBuffonandKantandGoetheandErasmusDarwinhadbeendisposedtoacceptitintheclosingdaysoftheeighteenthcentury。Then，in1809，ithadbeencontendedforbyoneoftheearlyworkersinsystematicpaleontology——JeanBaptisteLamarck，whohadstudiedthefossilshellsaboutPariswhileCuvierstudiedthevertebrates，andwhohadbeenledbythesestudiestoconcludethattherehadbeennotmerelyarotationbutaprogressionoflifeontheglobe。Hefoundthefossilshells——thefossilsofinvertebrates，ashehimselfhadchristenedthem——indeeperstratathanCuvier’svertebrates；
andhebelievedthattherehadbeenlongageswhennohigherformsthanthesewereinexistence，andthatinsuccessiveagesfishes，andthenreptiles，hadbeenthehighestofanimatecreatures，beforemammals，includingman，appeared。Lookingbeyondthepaleofhisbarefacts，asgeniussometimeswill，hehadinsistedthattheseprogressivepopulationshaddevelopedonefromanother，underinfluenceofchangedsurroundings，inunbrokenseries。
Ofcoursesuchathoughtasthiswashopelesslymisplacedinagenerationthatdoubtedtheexistenceofextinctspecies，andhardlylesssointhegenerationthatacceptedcatastrophism；butithadbeenkeptalivebyhereandthereanadvocatelikeGeoffreySaint-Hilaire，andnowthebanishmentofcatastrophismopenedthewayforitsmorerespectfulconsideration。RespectfulconsiderationwasgivenitbyLyellineachrecurringeditionofhisPrinciples，butsuchconsiderationledtoitsunqualifiedrejection。InitsplaceLyellputforwardamodifiedhypothesisofspecialcreation。Heassumedthatfromtimetotime，astheextirpationofaspecieshadleftroom，sotospeak，foranewspecies，suchnewspecieshadbeencreateddenovo；andhesupposedthatsuchintermittent，spasmodicimpulsesofcreationmanifestthemselvesnowadaysquiteasfrequentlyasatanytimeinthepast。Hedidnotsayinsomanywordsthatnooneneedbesurprisedto-daywerehetoseeanewspeciesofdeer，forexample，comeupoutofthegroundbeforehim，\"pawingtogetfree，\"likeMilton’slion，buthistheoryimpliedasmuch。Andthattheory，letitbenoted，wasnotthetheoryofLyellalone，butofnearlyallhisassociatesinthegeologicworld。Thereisperhapsnootherfactthatwillbringhometoonesovividlytheadvanceinthoughtofourowngenerationastherecollectionthatsocrude，soalmostunthinkableaconceptioncouldhavebeenthecurrentdoctrineofsciencelessthanhalfacenturyago。
Thistheoryofspecialcreation，moreover，excludedthecurrentdoctrineofuniformitarianismasnightexcludesday，thoughmostthinkersofthetimedidnotseemtobeawareoftheincompatibilityofthetwoideas。ItmaybedoubtedwhetherevenLyellhimselffullyrealizedit。Ifhedid，hesawnoescapefromthedilemma，foritseemedtohimthattherecordintherocksclearlydisprovedthealternativeLamarckianhypothesis。
Andalmostwithoneaccordthepaleontologistsofthetimesustainedtheverdict。Owen，Agassiz，Falconer，Barrande，Pictet，Forbes，repudiatedtheideaasunqualifiedlyastheirgreatpredecessorCuvierhaddoneintheearliergeneration。Someofthemdid，indeed，cometobelievethatthereisevidenceofaprogressivedevelopmentoflifeinthesuccessiveages，butnosuchgradedseriesoffossilshadbeendiscoveredaswouldgivecountenancetotheideathatonespecieshadeverbeentransformedintoanother。Andtonearlyeveryonethisobjectionseemedinsuperable。
Butin1859appearedabookwhich，thoughnotdealingprimarilywithpaleontology，yetcontainedachapterthatrevealedthegeologicalrecordinanaltogethernewlight。ThebookwasCharlesDarwin’sOriginofSpecies，thechapterthatwonderfulcitationofthe\"ImperfectionsoftheGeologicalRecord。\"Inthisepoch-makingchapterDarwinshowswhatconditionsmustprevailinanygivenplaceinorderthatfossilsshallbeformed，howunusualsuchconditionsare，andhowprobableitisthatfossilsonceimbeddedinsedimentofasea-bedwillbedestroyedbymetamorphosisoftherocks，orbydenudationwhenthestrataareraisedabovethewater-level。Addtothisthefactthatonlysmallterritoriesoftheearthhavebeenexploredgeologically，hesays，anditbecomesclearthatthepaleontologicalrecordaswenowpossessitshowsbutamerefragmentofthepasthistoryoforganismsontheearth。Itisahistory\"imperfectlykeptandwritteninachangingdialect。Ofthishistorywepossessthelastvolumealone，relatingonlytotwoorthreecountries。
Ofthisvolumeonlyhereandthereashortchapterhasbeenpreserved，andofeachpageonlyhereandthereafewlines。\"Forapaleontologisttodogmatizefromsucharecordwouldbeasrash，hethinks，as\"foranaturalisttolandforfiveminutesonabarrenpointofAustraliaandthendiscussthenumberandrangeofitsproductions。\"
Thiscitationofobservations，whichwhenoncepointedoutseemedalmostself-evident，cameasarevelationtothegeologicalworld。Intheclarifiedviewnowpossibleoldfactstookonanewmeaning。ItwasrecalledthatCuvierhadbeenobligedtoestablishaneworderforsomeofthefirstfossilcreaturesheexamined，andthatBucklandhadnotedthatthenondescriptformswereintermediateinstructurebetweenalliedexistingorders。Morerecentlysuchintermediateformshadbeendiscoveredoverandover；sothat，tonamebutoneexample，Owenhadbeenable，withtheaidofextinctspecies，to\"dissolvebygradationstheapparentlywideintervalbetweenthepigandthecamel。\"
Owen，moreover，hadbeenledtospeakrepeatedlyofthe\"generalizedforms\"ofextinctanimals，andAgassizhadcalledthem\"syntheticorprophetictypes，\"thesetermsclearlyimplying\"thatsuchformsareinfactintermediateorconnectinglinks。\"Darwinhimselfhadshownsomeyearsbeforethatthefossilanimalsofanycontinentarecloselyrelatedtotheexistinganimalsofthatcontinent——edentatespredominating，forexample，inSouthAmerica，andmarsupialsinAustralia。
Manyobservershadnotedthatrecentstrataeverywhereshowafossilfaunamorenearlyliketheexistingonethandomoreancientstrata；andthatfossilsfromanytwoconsecutivestrataarefarmorecloselyrelatedtoeachotherthanarethefossilsoftworemoteformations，thefaunaofeachgeologicalformationbeing，indeed，inawideview，intermediatebetweenprecedingandsucceedingfaunas。
SosuggestivewerealltheseobservationsthatLyell，theadmittedleaderofthegeologicalworld，afterreadingDarwin’scitations，feltabletodrophisowncrassexplanationoftheintroductionofspeciesandadoptthetransmutationhypothesis，thusroundingoutthedoctrineofuniformitarianismtothefullproportionsinwhichLamarckhadconceivedithalfacenturybefore。
Notallpaleontologistscouldfollowhimatonce，ofcourse；theproofwasnotyetsufficientlydemonstrativeforthat；butallwereshakenintheseemingsecurityoftheirformerposition，whichisalwaysanecessarystageintheprogressofthought。Andpopularinterestinthematterwasraisedtowhiteheatinatwinkling。
So，forthethirdtimeinthisfirstcenturyofitsexistence，paleontologywascalledupontoplayaleadingroleinacontroversywhoseinterestextendedfarbeyondtheboundsofstaidtruth-seekingscience。Andthecontroversywagedovertheageoftheearthhadnotbeenmorebitter，thatovercatastrophismnotmoreacrimonious，thanthatwhichnowragedoverthequestionofthetransmutationofspecies。Thequestionhadimplicationsfarbeyondtheboundsofpaleontology，ofcourse。Themainevidenceyetpresentedhadbeendrawnfromquiteotherfields，butbycommonconsenttherecordintherocksmightfurnishacrucialtestofthetruthorfalsityofthehypothesis。\"Hewhorejectsthisviewoftheimperfectionsofthegeologicalrecord，\"saidDarwin，\"willrightlyrejectthewholetheory。\"
Withsomethingmorethanmerescientificzeal，therefore，paleontologiststurnedanewtotherecordsintherocks，toinquirewhatevidenceinprooforrefutationmightbefoundinunreadpagesofthe\"greatstonebook。\"And，asmighthavebeenexpected，manymindsbeingthuspreparedtoreceivenewevidence，suchevidencewasnotlongwithheld。