第15章

Ourunitsoflinearextensionarethelengthsofmassesofmatterorthe

spacesbetweenmarksmadeonthemasses，andweassumetheselengths，or

thesespacesbetweenmarks，toremainunchangedwhilethetemperatureis

unchanged。Fromthestandard—measurepreservedatWestminster，arederived

themeasuresfortrigonometricalsurveys，forgeodesy，themeasurementof

terrestrialarcs，andthecalculationsofastronomicaldistances，dimensions，

etc。，andthereforeforAstronomyatlarge。Weretheseunitsoflength，original

andderived，irregularlyvariable，therecouldbenocelestialdynamics，

noranyofthatverificationyieldedbyitoftheconstancyofthecelestial

massesandoftheirenergies。Hence，persistenceofthespace—occupyingspecies

offorcecannotbeproved，forthereasonthatitistacitlyassumedinevery

experimentorobservationbywhichitisproposedtoproveit。Thelikeholds

oftheforcedistinguishedasenergy。Theendeavourtoestablishthisby

measurement，takesforgrantedboththepersistenceoftheintrinsicforce

bywhichbodymanifestsitselfasexisting，andthepersistenceoftheextrinsic

forcebywhichbodyacts。Foritisfromtheseequalunitsoflinearextension，

throughthemediumoftheequal—armedleverorscales，thatwederiveour

equalunitsofweight，orgravitativeforce;andonlybymeansofthesecan

wemakethosequantitativecomparisonsbywhichthetruthsofexactscience

arereached。Throughouttheinvestigationsleadingthechemisttotheconclusion

thatofthecarbonwhichhasdisappearedduringcombustion，noportionhas

beenlost，whatishisrepeatedly—assignedproof？Thataffordedbythescales。

Inwhattermsistheverdictofthescalesgiven？Ingrammes——inunits

ofweight——inunitsofgravitativeforce。Andwhatisthetotalcontent

oftheverdict？Thatasmanyunitsofgravitativeforceasthecarbonexhibited

atfirst，itexhibitsstill。Thevalidityoftheinference，then，depends

entirelyupontheconstancyoftheunitsofforce。Iftheforcewithwhich

theportionofmetalcalledagramme—weighttendstowardstheEarth，has

varied，theinferencethatmatterisindestructibleisvicious。Everything

turnsonthetruthoftheassumptionthatthegravitationoftheweights

ispersistent;andofthisnoproofisassigned，orcanbeassigned。Inthe

reasoningsoftheastronomerthereisalikeimplication，fromwhichwemay

drawthelikeconclusion。Noproblemincelestialdynamicscanbesolved

withouttheassumptionofsomeunitofforce。Thisunitneednotbe，like

apoundoraton，oneofwhichwecantakedirectcognizance。Itisrequisite

onlythatthemutualattractionwhichsometwoofthebodiesconcernedexercise

atagivendistance，shallbetakenasone;sothattheotherattractions

withwhichtheproblemdeals，maybeexpressedintermsofthisone。Such

unitbeingassumed，themotionswhichtherespectivemasseswillgenerate

inoneanotherinagiventime，arecalculated;andcompoundingthesewith

themotionstheyalreadyhave，theirplacesattheendofthattimearepredicted。

Thepredictionisverifiedbyobservation。Fromthis，eitheroftwoinferences

maybedrawn。Assumingthemassestobeunchanged，theirenergiesmaybe

provedundiminished;orassumingtheirenergiesundiminished，themasses

maybeprovedunchanged。Butthevalidityofoneorotherinferencedepends

whollyonthetruthoftheassumptionthattheunitofforceisunchanged。

Letitbesupposedthatthegravitationofthetwobodiestowardseachother

atthegivendistancehasvaried，andtheconclusionsdrawnarenolonger

true。Norisitonlyintheirconcretedatathatthereasoningsofterrestrial

andcelestialphysicsassumethePersistenceofForce。Theequalityofaction

andreactionistakenforgrantedfrombeginningtoendofeitherargument;

andtoassertthatactionandreactionareequalandopposite，istoassert

thatForcepersists。Theimplicationisthattherecannotbeanisolated

force，butthatanyforcemanifestedimpliesanequalantecedentforcefromwhichitisderived，andagainstwhichitisareaction。Wemightindeedbecertain，evenintheabsenceofanysuchanalysisas

theforegoing，thattheremustexistsomeprinciplewhich，asbeingthebasis

ofscience，cannotbeestablishedbyscience。Allreasoned—outconclusions

whatevermustrestonsomepostulate。Asbeforeshown（§23），wecannot

goonmergingderivativetruthsinthosewidertruthsfromwhichtheyare

derived，withoutreachingatlastawidesttruthwhichcanbemergedinno

other，orderivedfromnoother。Andtherelationinwhichitstandstothe

truthsofscienceingeneral，showsthatthistruthtranscendingdemonstration

isthePersistenceofForce。Tothisanultimateanalysisbringsusdown，andonthisarationalsynthesismustbuildup。§62。Butnowwhatistheforceofwhichwepredicatepersistence？

Thatwhichthewordordinarilystandsforistheconsciousnessofmuscular

tension——thefeelingofeffortwhichwehaveeitherwhenputtingsomethinginmotionorwhenresistingapressure。Thisfeeling，however，isbutasymbol。In§18itwassaidthatthough，sinceactionandreactionareequal

andopposite，weareobligedtothinkofthedownwardpullofaweightas

equaltotheupwardpullwhichsupportsit，andthoughthethoughtofequality

suggestskinshipofnature，yet，aswecannotascribefeelingtotheweight，

weareobligedtoadmitthatForceasitexistsbeyondconsciousnesshas

nolikenesstoforceasweconceiveit，thoughthereisbetweenthemthe

kindofequivalenceimpliedbysimultaneousvariation。Theeffortofone

whothrowsacricketballisfollowedbythemotionoftheballthroughspace，

anditsmomentumisre—transformedintomuscularstraininonewhocatches

it。Whattheforcewaswhenitexistedintheflyingcricketballitisimpossible

toimagine:wehavenotermsofthoughtinwhichtorepresentit。Andit

isthuswithallthetransformationsofenergytakingplaceintheworld

around。Thoseillustrationsgivenin§66，showingthechangesofform

whichenergyundergoesandtheequivalencebetweensomuchofitinoneform

andsomuchinanother，failtoenlightenusrespectingtheenergyitself。

Itassumesunderthisorthatsetofconditionsthisorthatshape，andthe

quantityofitisnotalteredduringitstransformations。Forthatinterpretation

ofthingswhichisalonepossibleforusthisisallwerequiretoknow——

thattheforceorenergymanifested，nowinonewaynowinanother，persists

orremainsunchangedinamount。Butwhenweaskwhatthisenergyis，there

isnoanswersavethatitisthenoumenalcauseimpliedbythephenomenaleffect。HencetheforceofwhichweassertpersistenceisthatAbsoluteForce

weareobligedtopostulateasthenecessarycorrelateoftheforceweare

consciousof。BythePersistenceofForce，wereallymeanthepersistence

ofsomeCausewhichtranscendsourknowledgeandconception。InassertingitweassertanUnconditionedReality，withoutbeginningorend。Thus，quiteunexpectedly，wecomedownoncemoretothatultimatetruth

inwhich，aswesaw，ReligionandSciencecoalesce——thecontinuedexistence

ofanUnknowableasthenecessarycorrelativeoftheKnowable。

Chapter7ThePersistenceofRelationAmongForces§63。Thefirstdeductiontobedrawnfromtheultimateuniversal

truththatforcepersists，isthattherelationsamongforcespersist。Supposing

agivenmanifestationofforce，underagivenformandgivenconditions，

beeitherprecededbyorsucceededbysomeothermanifestation，itmust，

inallcaseswheretheformandconditionsarethesame，beprecededbyor

succeededbysuchothermanifestation。EveryantecedentmodeoftheUnknowable

musthaveaninvariableconnexion，quantitativeandqualitative，withthatmodeoftheUnknowablewhichwecallitsconsequent。Fortosayotherwiseistodenythepersistenceofforce。Ifinanytwo

casesthereisexactlikenessnotonlybetweenthoseconspicuousantecedents

whichwecallthecauses，butalsobetweenthoseaccompanyingantecedents

whichwecalltheconditions，wecannotaffirmthattheeffectswilldiffer，

withoutaffirmingeitherthatsomeforcehascomeintoexistenceorthat

someforcehasceasedtoexist。Iftheco—operativeforcesintheonecase

areequaltothoseintheother，eachtoeach，indistributionandamount;

thenitisimpossibletoconceivetheproductoftheirjointactioninthe

onecaseasunlikethatintheother;withoutconceivingoneormoreofthe

forcestohaveincreasedordiminishedinquantity;andthisisconceivingthatforceisnotpersistent。Toimpressthetruththusenunciatedunderitsmostabstractform，someillustrationswillbedesirable。§64。Lettwobullets，equalinweightsandshapes，beprojectedwith

equalenergies;then，inequaltimes，equaldistancesmustbetravelledby

them。Theassertionthatoneofthemwilldescribeanassignedspacesooner

thantheother，thoughtheirinitialmomentawerealikeandtheyhavebeen

equallyresisted（foriftheyareunequallyresistedtheantecedentsdiffer）

isanassertionthatequalquantitiesofforcehavenotdoneequalamounts

ofwork;andthiscannotbethoughtwithoutthinkingthatsomeforcehas

disappearedintonothingorarisenoutofnothing。Assume，furtherthatduring

itsnightoneofthemhasbeendrawnbytheEarthacertainnumberofinches

outofitsoriginallineofmovement;thentheother，whichhasmovedthe

samedistanceinthesametime，musthavefallenjustasfartowardsthe

Earth。Nootherresultcanbeimaginedwithoutimaginingthatequalattractions

actingforequaltimes，haveproducedunequaleffects;whichinvolvesthe

inconceivablepropositionthatsomeactionhasbeencreatedorannihilated。

Again，oneofthebulletshavingpenetratedthetargettoacertaindepth，

penetrationbytheotherbullettoasmallerdepth，unlesscausedbygreater

localdensityinthetarget，cannotbementallyrepresented。Suchamodification

oftheconsequentswithoutmodificationoftheantecedents，isthinkable

onlythroughtheimpossiblethoughtthatsomethinghasbecomenothingornothinghasbecomesomething。Itisthusnotwithsequencesonly，butalsowithsimultaneouschanges

andpermanentco—existences。Givenchargesofpowderalikeinquantityand

quality，firedfrombarrelsofthesamestructure，andpropellingbullets

ofequalweights，sizes，andforms，similarlyrammeddown;*<*Thiswas

writtenwhilemuzzle—loadingwasstillusual。>anditisanecessary

inferencethattheconcomitantactionswhichmakeuptheexplosion，will

beartooneanotherlikerelationsofquantityandqualityinthetwocases。

Theproportionsamongthedifferentproductsofcombustionwillbeequal。

Theseveralamountsofenergytakenupingivingmomentumtothebullet，

heattothegases，andsoundontheirescape，willpreservethesameratios。

Thequantitiesoflightandsmokeintheonecasewillbewhattheyarein

theother;andthetworecoilswillbealike。Fornodifference，ofrelation

amongtheseconcurrentphenomenacanbeimaginedasarising，withoutimaginingitasarisingbythecreationorannihilationofenergy。Thatwhichholdsbetweenthesetwocasesmustholdamonganynumberof

cases;andthatwhichhereholdsbetweencomparativelysimpleantecedents

andconsequents，mustholdhoweverinvolvedtheantecedentsbecomeandhoweverinvolvedtheconsequentsbecome。§65。ThusUniformityofLaw，resolvableaswefinditintothepersistence

ofrelationsamongforces，isacorollaryfromthepersistenceofforce。

Thegeneralconclusionthatthereexistconstantconnexionsamongphenomena，

ordinarilyregardedasaninductiveconclusiononly，isreallyaconclusiondeduciblefromtheultimatedatumofconsciousness。Morethanthismaybesaid。Everyapparentinductiveproofoftheuniformity

oflawitselftakesforgrantedboththepersistenceofforceandthepersistence

ofrelationsamongforces。Forintheexactsciences，inwhichalonewemay

seekrelationsdefiniteenoughtoproveuniformity，anyallegeddemonstration

mustdependonmeasurement;andaswehavealreadyseen，measurement，whether

ofmatterorforce，assumesthatbotharepersistentinassumingthatthe

measureshavenotvaried。Whileatthesametimeeverydeterminationofthe

relationsamongthem——inamount，proportion，direction，orwhatnot——

similarlyimpliesmeasurement，thevalidityofwhichasbeforeimpliesthepersistenceofforce。Thatuniformityoflawthusfollowsinevitablyfromthepersistenceof

force，willbecomemoreandmoreclearasweadvance。Thenextchapterwill

indirectlysupplyabundantfrustrationsofit。

Chapter8TheTransformationandEquivalenceofForces§66。When，totheunaidedsenses，Sciencebegantoaddsupplementary

sensesintheshapeofmeasuringinstruments，menbegantoperceivevarious

phenomenawhicheyesandfingerscouldnotdistinguish。Ofknownformsof

force，minutermanifestationsbecameappreciable;andformsofforcebefore

unknownwererenderedcognizableandmeasurable。Whereforceshadapparently

endedinnothing，andhadbeencarelesslysupposedtohaveactuallydone

so，instrumentalobservationprovedthateffectshadineveryinstancebeen

produced:theforceshavingreappearedinnewshapes。Herehasatlength

arisentheinquirywhethertheforcedisplayedineachsurroundingchange，

doesnotintheactofexpenditureundergometamorphosisintoanequivalent

amountofsomeotherforceorforces。Andtothisinquiryexperimentisgiving

anaffirmativeanswer，whichbecomesdailymoredecisive。Séguin，

Mayer，Joule，Grove，andHelmholtz，aremorethanotherstobecreditedwith

theenunciationofthisdoctrine。Letusglanceattheevidenceonwhichitrests。Motion，whereverwecandirectlytraceitsgenesis，wefindhadpre—existed

assomeothermodeofforce。Ourownvoluntaryactshavealwayscertainsensations

ofmusculartensionastheirantecedents。When，asinlettingfallarelaxed

limbweareconsciousofabodilymovementrequiringnoeffort，theexplanation

isthattheeffortwasexertedinraisingthelimbtothepositionwhence

itfell。Inthiscase，asinthecaseofaninanimatebodydescendingto

theEarth，theforceaccumulatedbythedownwardmotionisequaltotheforce

previouslyexpendedintheactofelevation。Conversely，Motionthatisarrested

produces，underdifferentcircumstances，heat，electricity，magnetism，light。

Fromthewarmingofthehandsbyrubbingthemtogether，uptotheignition

ofarailway—brakebyintensefriction——fromthelightingofdetonating

powderbypercussion，uptothesettingonfireablockofwoodbyafew

blowsfromasteam—hammer;wehaveabundantinstancesinwhichheatarises

asMotionceases。Itisuniformlyfoundthattheheatgeneratedisgreat

inproportionastheMotionlostisgreat;andthattodiminishthearrest

ofmotionbydiminishingthefriction，istodiminishthequantityofheat

evolved。TheproductionofelectricitybyMotionisillustratedequallyin

theboy\'sexperimentwithrubbedsealing—wax，inthecommonelectricalmachine，

andintheapparatusforexcitingelectricitybytheescapeofsteam。Wherever

thereisfrictionbetweenheterogeneousbodieselectricaldisturbanceis

oneoftheconsequences。MagnetismmayresultfromMotioneitherimmediately，

asthroughpercussiononsteel，ormediatelyasthroughelectriccurrents

previouslygeneratedbyMotion。Andsimilarly，Motionmaycreatelight;either

directly，asintheminuteincandescentfragmentsstruckoffbyviolentcollisions，

orindirectly，asthroughtheelectricspark。"Lastly，Motionmaybe

againreproducedbytheforceswhichhaveemanatedfromMotion;thus，the

divergenceoftheelectrometer，therevolutionoftheelectricalwheel，the

deflectionofthemagneticneedle，are，whenresultingfromfrictionalelectricity

palpablemovementsreproducedbytheintermediatemodesofforce，whichhavethemselvesbeenoriginatedbymotion。"ThatmodeofforcewhichwedistinguishedasHeat，isnowregardedas

molecularmotion——notmotionasdisplayedinthechangedrelationsofsensible

massestooneanother，butasassessedbytheunitsofwhichsuchsensible

massesconsist。Omittingcasesinwhichthereisstructuralrearrangement

ofthemolecules，heatedbodiesexpand;andexpansionisinterpretedasdue

tomovementsofthemoleculesinrelationtooneanother:wideroscillations。

Thatradiationthroughwhichanythingofhighertemperaturethanthingsaround

it，communicatesHeattothem，isclearlyaspeciesofmotion。Moreover，

theevidenceaffordedbythethermometerthatHeatthusdiffusesitself，

issimplyamovementcausedinthemercurialcolumn。Andthatthemolecular

motionwhichwecallHeat，maybetransformedintovisiblemotion，familiar

proofisgivenbythesteam—engine;inwhich"thepistonandallits

concomitantmassesofmatteraremovedbythemoleculardilatationofthe

vapourofwater。"WhereHeatisabsorbedwithoutapparentresult，modern

inquirieshavedetectedunobtrusivemodifications:asinglass，themolecular

stateofwhichissofarchanged，thataAlarizedrayoflightpassingthrough

itbecomesvisible，whichitdoesnotwhentheglassiscold;orasonpolished

metallicsurfaces，whicharealteredinmolecularstructurebyradiations

fromobjectsveryclosetothem。ThetransformationofHeatintoelectricity

occurswhendissimilarmetalstouchingeachotherareheatedatthepoint

ofcontact:electriccurrentsbeingsoproduced。Solid，incombustiblematter

putintoheatedgas，aslimeintotheOxyhydrogenflame，becomesincandescent;

andsoexhibitstheconversionofHeatintolight。Theproductionofmagnetism

byHeat，ifitcannotbeprovedtotakeplacedirectly，maybeprovedto

takeplaceindirectlythroughtheagencyofelectricity。Andthroughthe

sameagencymaybeestablishedthecorrelationofHeatandchemicalaffinity

——acorrelationwhichisdirectlyshownbythemarkedinfluenceHeatexercisesonchemicalcompositionanddecomposition。ThetransformationsofElectricityintoothermodesofforceareclearly

demonstrable。Producedbythemotionofheterogeneousbodiesincontact，

Electricity，throughattractionsandrepulsions，willimmediatelyreproduce

motioninneighbouringbodies。InthiscaseacurrentofElectricitymagnetizes

abarofsoftiron;andinthatcasetherotationofanequippedmagnetgenerates

currentsofElectricity。Hereisthecellofabatteryinwhich，fromthe

playofchemicalaffinities，anelectriccurrentresults;andthere，inthe

adjacentcell，isanelectriccurrenteffectingchemicaldecomposition。In

theconductingwirewewitnessthetransformationofElectricityintoheat;

whileinelectricsparksandinthevoltaicarcweseelightproduced。Molecular

arrangement，too，ischangedbyElectricity:asinstancethetransferof

matterfrompoletopoleofabattery;thefracturescausedbythedisruptive

discharge;theformationofcrystalsundertheinfluenceofelectriccurrents。

Andthenthat，conversely，Electricityisdirectlygeneratedbyrearrangement

ofthemoleculesofmatter，isshownwhenastorage—batteryoraccumulatorisused。HowfromMagnetismtheotherphysicalforcesresult，mustbenextbriefly

noted——briefly，becauseineachsuccessivecasetheillustrationsbecome

ingreatparttheobverseformsofthosebeforegiven。ThatMagnetismproduces

motionistheordinaryevidencewehaveofitsexistence。Inthemagneto—electric

machinearotatingmagnetevolveselectricity。andtheelectricitysoevolved

mayimmediatelyafterexhibititselfasheat，light，orchemicalaffinity。

Faraday\'sdiscoveryoftheeffectofMagnetismonpolarizedlight，aswell

asthediscoverythatchangeofmagneticstateisaccompaniedbyheat，point

tofurtherlikeconnexions。Lastly，experimentsshowthatthemagnetization

ofabodyaltersitsinternalstructure;andthat，conversely，thealterationofitsinternalstructure，asbymechanicalstrain，altersitsmagneticcondition。Improbableasitseemed，itisnowprovedthatfromLightalsomayproceed

thelikevarietyofagencies。Raysoflightchangetheatomicarrangements

ofparticularcrystals。Certainmixedgases，whichdonototherwisecombine，

combineinthesunshine。Insomecompoundslightproducesdecomposition。

Sincetheinquiriesofphotographershavedrawnattentiontothesubject，

ithasbeenshownthat"avastnumberofsubstances，bothelementary

andcompound，arenotablyaffectedbythisagent，eventhoseapparentlythe

mostunalterableincharacter，suchasmetals。"Andwhenadaguerreotype

plateisconnectedwithaproperapparatus"wegetchemicalactionon

theplate，electricitycirculatingthroughthewires，magnetisminthecoil，heatinthehelix，andmotionintheneedles。"ThegenesisofallothermodesofforcefromChemicalAction，scarcely

needspointingout。Theordinaryaccompanimentofchemicalcombinationis

heat;andwhentheaffinitiesareintense，lightalsoisproduced。Chemical

changesinvolvingalterationofbulk，causemotion，bothinthecombining

elementsandinadjacentmassesofmatter:witnessthepropulsionofabullet

bytheexplosionofgunpowder。Inthegalvanicbatteryweseeelectricity

resultingfromchemicalcompositionanddecomposition。Whilethroughthemediumofthiselectricity，ChemicalActionproducesmagnetism。Thesefacts，thelargerpartofwhichareculledfromGrove\'sworkonTheCorrelationofPhysicalForces，showthateachforceistransformable，

directlyorindirectly，intotheothers。IneverychangeForce（orEnergy，

asinthesecasesitiscalled）undergoesmetamorphosis;andfromthenew

formorformsitassumes，maysubsequentlyresulteitherthepreviousone

oranyoftherest，inendlessvarietyoforderandcombination。Itisfurther

nowmanifestthatthephysicalforcesstandnotsimplyinqualitativecorrelations

withoneanother，butalsoinquantitativecorrelations。Besidesproving

thatonemodeofforcemaybetransformedintoanothermode，experiments

showthatfromadefiniteamountofone，theamountsofothersthatarise

aredefinite。Ordinarilyitisdifficulttoshowthis;sinceitmostlyhappens

thatthetransformationofanyforceisnotintosomeoneoftherestbut

intoseveralofthem:theproportionsbeingdeterminedbyever—varyingconditions。

Butincertaincasespositiveresultshavebeenreached。Mr。Joulehasascertained

thatthefallof772lb。throughonefoot，willraisethetemperatureof

apoundofwateronedegreeofFahrenheit。Dulong，Petit，andNeumann，have

provedarelationinamountbetweentheaffinitiesofcombiningbodiesand

theheatevolvedduringtheircombination。Betweenchemicalactionandvoltaic

electricityaquantitativeconnexionhasbeenestablishedbyFaraday。The

well—determinedrelationsbetweentheamountsofheatgeneratedandofwater

turnedtosteam，orstillbettertheknownexpansionproducedinsteamby

eachadditionaldegreeofheat，maybecitedinfurtherevidence。Henceit

isnolongerdoubtedthatamongtheseveralformswhichforceassumes，thequantitativerelationsarefixed。###第16章§67。ThroughouttheCosmosthistruthmustinvariablyhold。Every

change，orgroupofchanges，goingoninit，mustbeduetoforcesaffiliable

onthelikeorunlikeforcespreviouslyexisting;whilefromtheforcesexhibited

insuchchangeorchangesmustbederivedothersmoreorlesstransformed。

Andbesidesrecognizingthisnecessarylinkingoftheforcesatanytime

manifestedwiththoseprecedingandsucceedingthem，wemustrecognizethe

amountsoftheseforcesasnecessarilyproducingsuchandsuchquantitiesofresults，andasnecessarilylimitedtothosequantities。ThatunificationofknowledgewhichisthebusinessofPhilosophy，is

butlittlefurtheredbytheestablishmentofthistruthunderitsgeneral

form。Wemusttraceitoutunderitsleadingspecialforms。Changes，and

theaccompanyingtransformationsofforces，areeverywhereinprogress，from

themovementsofstarstothecurrentsofcommodities;andtocomprehend

thegreatfactthatforces，unceasinglymetamorphosed，arenowhereincreased

ordecreased，itisrequisitetocontemplatethechangesofallkindsgoing

onthatwemaylearnwhencearisetheforcestheyandwhatbecomesofthese

forces。Ofcourseifanswerableatall，thesequestionscanbeansweredonly

intheestablishrudestway。Themostwecanhopeistoestablishaqualitative

correlationthatisindefinitelyquantitative——quantitativetotheextentofimplyingsomethinglikeadueproportionbetweencausesandeffects。Letus，then，considertheseveralclassesofphenomenawhichtheseveralconcretesciencesdealwith。§68。TheantecedentsofthoseforceswhichourSolarSystemdisplays，

belongtoapastofwhichwecanneverhaveanythingbutinferentialknowledge。

ManyandstrongasarethereasonsforbelievingtheNebularHypothesis，

wecannotyetregarditasmorethananhypothesis。If，however，weassume

thatthematterofourSolarSystemwasoncediffusedandhadirregularities

ofshapeanddensitysuchasexistingnebulaedisplay，orresultedfromthe

coalescencesofmovingnebulousmasses，wehave，inthemomentaofitsparts，originalandacquiredforcesadequatetoproducethemotionsnowgoingon。Variousstagesintheformationofspiralnebulaeimplythatrotation

inmanycasesresultsfromconcentration:whetheralways，thereisnoproof;

forlargenebulaearetoodiffused，smallonestoodense，andothersare

seentoomuchedgeways，toyieldevidence。Butintheabsenceofadverse

pre—arrangementsomerotationmaysafelybeinferred。Sofarastheevidence

carriesus，weperceivesomequantitativerelationbetweenthemotionsgenerated

andthegravitativeforcesexpendedingeneratingthem。IntheSolarSystem

theoutermostplanets，formedfromthatmatterwhichhastravelledtheshortest

distancetowardsthecommoncentreofgravity，havethesmallestvelocities。

Doubtlessthisisexplicableontheteleologicalhypothesis，sinceitis

aconditiontoequilibrium。Butwithoutinsistingthatthisisbesidethe

question，itwillsufficetopointoutthatthelikecannotbesaidofthe

planetaryrotations。Nosuchfinalcausecanbeassignedfortherapidaxial

movementofJupiterandSaturn，ortheslowaxialmovementofMars。If，however，

welookforthenaturalantecedentsofthesegyrationswhichallplanets

exhibit，thenebularhypothesisfurnishesthem;andtheybearmanifestquantitative

relationstotheratesofmotions。Fortheplanetsthatturnontheiraxes

withextremerapidityarethosehavinglargeorbits——thoseofwhichthe

once—diffusedcomponents，probablyformedintobroadrings，movedtotheir

centresofaggregationinimmensespaces，andsoacquiredhighvelocities。

Whileconversely;theplanetswhichrotatewithrelativelysmallvelocities，arethoseformedoutofsmallnebulousrings。"Butwhat，"itmaybeasked，"hasinsuchcasebecomeof

allthatmotionwhichendedintheaggregationofthisdiffusedmatterinto

solidbodies？"Theansweristhatithasbeenradiatedintheformof

heatandlight;andthisanswertheevidence，sofarasitgoes，confirms。

GeologistsandphysicistsagreeinconcludingthattheheatoftheEarth\'s

interiorisbutaremnantoftheheatwhichoncemademoltenthewholemass。

ThemountainoussurfacesoftheMoonandofVenus，indicating，astheydo，

crustswhichhave，likeourown，beencorrugatedbycontraction，implythat

thesebodies，too，haveundergonerefrigeration。LastlywehaveintheSun

astill—continuedproductionoftheheatandlightwhichresultfromthe

arrestofdiffusedmattermovingtowardsacommoncentreofgravity。Here

also，asbefore，aquantitativerelationistraceable。Mars，theEarth，Venus，

andMercury，whichseverallycontaincomparativelysmallamountsofmatter

whosecentripetalmotionhasbeendestroyed，havealreadylostnearlyall

theproducedheat;whilethegreatplanets，JupiterandSaturn，implyby

theirlowspecificgravity，aswellasbytheperturbationsoftheirsurfaces，

thattheystillretainmuchheat。AndthentheSun，athousandtimesasgreat

inmassasthelargestplanet，andhavingtogiveoffanenormouslygreater

quantityofheatandlightduetothatlossofmolarmotionwhichconcentrationentails，isstillradiatingwithgreatintensity。§69。Thoseforceswhichhavewroughtthesurfaceofourplanetinto

itspresentshape，aretraceabletotheprimordialsourcejustassigned。

Geologicchangesareeitherdirectorindirectresultsoftheunexpended

heatcausedbynebularcondensation。Theyarecommonlydividedintoigneousandaqueous——headsunderwhichwemaymostconvenientlyconsiderthem。Allthosedisturbancesknownasearthquakes，allthoseelevationsand

subsidenceswhichtheyseverallyproduce，allthoseaccumulatedeffectsof

manysuchelevationsandsubsidencesexhibitedinocean—basins，islands，

continents，table—lands，mountain—chains，andallthoseformationswhich

aredistinguishedasvolcanic，geologistsnowregardasmodificationsof

theEarth\'scrustcausedbytheactionsandreactionsofitsinterior。Even

supposingthatvolcaniceruptions，extrusionsofigneousrock，andupheaved

mountain—chains，couldbeotherwisesatisfactorilyaccountedfor，itwould

beimpossibleotherwisetoaccountforthosewide—spreadelevationsanddepressions

whencecontinentsandoceansresult。Suchphenomenaasthefusionoragglutination

ofsedimentarydeposits，thewarmingofsprings，thesublimationofmetals

intothefissureswherewefindthemasores，mayberegardedaspositive

resultsoftheresiduaryheatoftheEarth\'sinterior;whilefracturesof

strataandalterationsoflevelareitsnegativeresults，sincetheyensue

onitsescape。Theoriginalcauseofalltheseeffectsisstill，however，

asithasbeenfromthefirst，thegravitatingmovementoftheEarth\'smatter

towardstheEarth\'scentre;seeingthattothisisdueboththeeternalheatitselfandthecollapsewhichtakesplaceasitisradiatedintospace。Tothequestion——Underwhatformspreviouslyexistedtheforcewhich

worksoutthegeologicalchangesclassedasaqueous，theanswerislessobvious。

Theeffectsofrain，ofrivers，ofwinds，ofwaves，ofmarinecurrents，do

notmanifestlyproceedfromonegeneralsource。Analysis，nevertheless，proves

thattheyhaveacommongenesis。Ifweask，——Whencecomesthepowerof

theriver—current，bearingsedimentdowntothesea？thereplyis，——The

gravitationofwaterthroughoutthetractwhichthisriverdrains。Ifwe

ask，——Howcamethewatertobedispersedoverthistract？thereplyis，

——Itfellintheshapeofrain。Ifweask，——Howcametheraintobein

thatpositionwhenceitfell？thereplyis，——Thevapourfromwhichitwas

condensedwasdriftedtherebythewinds。Ifweask，——Howcamethisvapour

tobeatthatheight？thereplyis，——Itwasraisedbyevaporation。And

ifweask，——Whatforcethusraisedit？thereplyis，——TheSun\'sheat。

JustthatamountofgravitativeforcewhichtheSun\'sheatovercameinraising

themoleculesofwater，isgivenoutagaininthefallofthosemolecules

tothesamelevel。Hencethedenudationseffectedbyrainandrivers，during

thedescentofthiscondensedvapourtothelevelofthesea，areindirectly

duetotheradiatedenergyoftheSun。Similarlywiththewindsthattransport

thevapourshitherandthither。Consequentasatmosphericcurrentsareon

differencesoftemperature（eithergeneral，asbetweentheequatorialand

polarregions，orspecialasbetweentractsoftheEarth\'ssurfacehaving

unlikephysicalcharacters）allsuchcurrentsareduetothatsourcefrom

whichtheirregularlydistributedheatproceeds。Andifthewindsthusoriginate，

sotoodothewavesraisedbythemonthesea\'ssurface。Whenceitfollows

thatwhateverchangeswavesproduce——thewearingawayofcliffs，thebreaking

downofrocksintoshingle，sand，andmud——arealsotraceabletothesolar

raysastheirprimarycause。Thesamemaybesaidofocean—currents。Generated

asthelargeronesarebytheexcessofheatwhichtheoceanintropical

climatesacquiresfromtheSun;anddeterminedasthesmalleronesarein

partbylocalshapesofland;itfollowsthatthedistributionofsediment

andothergeologicalprocesseswhichthesemarinecurrentseffect，areaffiliable

upontheenergytheSunradiates。Theonlyaqueousagencyotherwiseoriginating

isthatofthetides——anagencywhich，equallywiththeothers，istraceable

tounexpendedcelestialmotion。Butmakingallowanceforthechangesthis

works，weconcludethattheslowwearingdownofcontinentsandgradualfilling

upofseas，effectedbyrain，rivers，winds，waves，andocean—streams，aretheindirecteffectsofsolarheat。Thusweseethatwhilethegeologicalchangesclassedasigneous，arise

fromthestill—progressingmotionoftheEarth\'ssubstancetoitscentre

ofgravity;theantagonisticchangesclassedasaqueous，arisefromthestill—progressingmotionoftheSun\'ssubstancetowardsitscentreofgravity。§70。Thattheforcesexhibitedinvitalactions，vegetalandanimal，

aresimilarlyderived，isanobviousdeductionfromthefactsoforganic

chemistry。Letusnotefirstthephysiologicalgeneralizations;andthenthegeneralizationswhichtheynecessitate。Plant—lifeisalldirectlyorindirectlydependentontheheatandlight

oftheSun—directlydependentintheimmensemajorityofplants，andindirectly

dependentinplantswhich，asthefungi，flourishinthedark:sincethese，

growingattheexpenseofdecayingorganicmatter，mediatelydrawtheirforces

fromthesameoriginalsource。Eachplantowesthecarbonandhydrogenof

whichitmainlyconsists，tothecarbondioxideandwatercontainedinthe

surroundingairandearth。Thesemust，however，bedecomposedbeforetheir

carbonandhydrogencanbeassimilated。Toovercometheaffinitieswhich

holdtheirelementstogetherrequirestheexpenditureofenergy;andthis

energyissuppliedbytheSun。When，underfitconditions，plantsareexposed

tothesolarrays，theygiveoffoxygenandaccumulatecarbonandhydrogen。

Indarknessthisprocessceases。Itceases，too，whenthequantitiesoflight

andheatreceivedaregreatlyreduced，asinwinter。Conversely，itisactive

whenthelightandheataregreat，asinsummer。Andthelikerelationis

seeninthefactthatwhileplant—lifeisluxuriantinthetropics，itdiminishes

intemperateregions，anddisappearsasweapproachthepoles。Thustheirresistible

inferenceisthattheforcesbywhichplantsgrowandcarryontheirfunctions，areforceswhichpreviouslyexistedassolarradiations。Thatinthemain，theprocessesofanimallifeareoppositetothoseof

vegetallifeisatruthlongcurrentamongmenofscience。Chemicallyconsidered，

vegetallifeischieflyaprocessofde—oxidation，andanimallifechiefly

aprocessofoxidation;chieflywemustsay，becauseinsofarasplants

areexpendersofforceforthepurposesoforganization，theyareoxidizers;

andanimals，insomeoftheirminorprocesses，areprobablyde—oxidizers。

Butwiththisqualification，thegeneraltruthisthatwhiletheplant，decomposing

carbondioxideandwaterandliberatingoxygen，buildsupthedetainedcarbon

andhydrogen（alongwithalittlenitrogenandsmallquantitiesofother

elements）intostem，branches，leaves，andseeds;theanimal，consumingthese

branches，leaves，andseeds，andabsorbingoxygen，re—composescarbondioxide

andwater，formingalsocertainnitrogenouscompoundsinminoramounts。And

whilethedecompositioneffectedbytheplantisattheexpenseofenergies

emanatingfromtheSun，there—compositioneffectedbytheanimalisatthe

profitoftheseenergies，whichareliberatedduringthecombinationofsuch

elements。Thusthemovements，internalandexternal，oftheanimal，arere—appearances

innewformsofapowerabsorbedbytheplantundertheshapeoflightand

heat。Justasthesolarforcesexpendedinraisingvapourfromthesea\'s

surface，aregivenoutagaininthefallofrainandriverstothesamelevel，

andintheaccompanyingtransferofsolidmatters;so，thesolarforcesthat

intheplantraisedcertainchemicalelementstoaconditionofunstable

equilibrium，aregivenoutagainttheactionsoftheanimalduringthefalloftheseelementstoaconditionofstableequilibrium。Besidesthustracingaqualitativecorrelationbetweenthesetwogreat

ordersoforganicactivity，aswellasbetweenbothofthemandinorganic

activities，wemayrudelytraceaquantitativecorrelation。Wherevegetal

lifeisabundant，weusuallyfindabundantanimallife;andasweadvance

fromtorridtotemperateandfrigidclimates，thetwodecreasetogether。

Speakinggenerally，theanimalsofeachclassreachlargersizesinregionswherevegetationisluxuriant，thaninthosewhereitissparse。Certainfactsofdevelopmentinbothplantsandanimals，illustratestill

moredirectlythetruthweareconsidering。Inpursuanceofasuggestion

madebyMr。（afterwardsSirWilliam）Grove，Dr。Carpenterpointedoutthat

aconnexionbetweenphysicalandvitalforcesisexhibitedduringincubation。

Thetransformationoftheunorganizedcontentsofaneggintotheorganized

chick，isaquestionofheat:withholdheatandtheprocessdoesnotcommence;

supplyheatanditgoesonwhilethetemperatureismaintained，butceases

whentheeggisallowedtocool。Thedevelopmentalchangescanbecompleted

onlybykeepingthetemperaturewithtolerableconstancyatadefiniteheight

foradefinitetime;thatis——onlybysupplyingadefinitequantityof

heat。Thoughtheproclivitiesofthemoleculesdeterminethetypicalstructure

assumed，yettheenergysuppliedbythethermalundulationsgivesthemthe

powerofarrangingthemselvesintothatstructure。Inthemetamorphosesof

insectswemaydiscernparallelfacts。Thehatchingoftheireggsisdetermined

bytemperature，asisalsotheevolutionofthepupaintotheimago;and

bothareacceleratedorretardedaccordingasheatisartificiallysupplied

orwithheld。Itwillsufficejusttoadd，thatthegerminationofplantspresentslikerelationsofcauseandeffect，aseveryseasonshows。Thusthenthevariouschangesexhibitedbytheorganiccreation，whether

consideredasawhole，orinitstwogreatdivisions，orinitsindividualmembers，conform，sofaraswecanascertain，tothegeneralprinciple。§71。Evenafterallthathasbeensaidintheforegoingpartofthis

work，manywillbealarmedbytheassertionthattheforceswhichwedistinguish

asmental，comewithinthesamegeneralization。Yetthereisnoalternative

buttomakethisassertion:thefactswhichjustify，orratherwhichnecessitate，

itbeingabundantandconspicuous。Atthesametimetheyareextremelyinvolved。

Theessentialcorrelationsoccurinorganswhicharemostlyinvisible，and

betweenforcesorenergiesquiteotherthanthosewhichareapparent。Letusfirsttakeasuperficialviewoftheevidence。Themodesofconsciousnesscalledpressure，motion，sound，light，heat，

areeffectsproducedinusbyagencieswhichasotherwiseexpended，crush

orfracturepiecesofmatter，generatevibrationsinsurroundingobjects，

causechemicalcombinations，andreducesubstancesfromasolidtoaliquid

form。Henceifweregardthechangesofrelativeposition，ofaggregation，

orofchemicalunion，thusarising，asbeingtransformedmanifestationsof

certainenergies;so，too，mustweregardthesensationswhichsuchenergies

produceinus。Anyhesitationtoadmitthismustdisappearonremembering

thatthelastcorrelations，likethefirst，arenotqualitativeonlybut

quantitative。Massesofmatterwhich，byscalesordynamometer，areshown

todiffergreatlyinweight，differasgreatlyinthefeelingsofpressure

theyproduceonourbodies。Inarrestingmovingobjects，thestrainsweare

consciousofareproportionatetothemomentaofsuchobjectsasotherwise

measured。Theimpressionsofsoundsgiventousbyvibratingstrings，bells，

orcolumnsofair，arefoundtovaryinstrengthwiththeamountofforce

applied。Fluidsorsolidsprovedtobemarkedlycontrastedintemperature

bythedifferentdegreesofexpansiontheyproduceinthemercurialcolumn，

produceinuscorrespondinglydifferentdegreesofthesensationofheat。

Andunlikeintensitiesinourimpressionsoflight，answertounlikeeffectsasmeasuredbyphotometers。Besidesthecorrelationandequivalencebetweenexternalphysicalforces

andthementalforcesgeneratedbythemundertheformofsensations，there

appearstobeacorrelationandequivalencebetweensensationsandthose

physicalforceswhich，intheshapeofbodilyactions，resultfromthem。

Inadditiontotheexcitementsofsecretingorgans，sometimestraceable，

therearisecontractionsoftheinvoluntarymuscles。Sensationsincrease

theactionoftheheart，andrecentexperimentsimplythatthemuscularfibres

ofthearteriesareatthesametimecontracted。Therespiratorymuscles，

tooarestimulated。Therateofbreathingisvisiblyandaudiblyaugmented

bothbypleasurableandpainfulexcitementsofthenerves，ifthesereach

anyintensity。Whenthequantityofsensationisgreat，itgeneratescontractions

ofthevoluntarymuscles，aswellasoftheinvoluntaryones。Violentpains

causeviolentstruggles。Thestartthatfollowsaloudsound，thewryface

producedbyanextremelydisagreeabletaste，thejerkwithwhichthehand

orfootissnatchedoutofveryhotwaterexemplifythegenesisofmotions

byfeelings;andinthesecasesitismanifestthatthequantityofbodily。

actionisproportionatetothequantityofsensation。evenwherepridecauses

suppressionofthescreamsandgroansexpressiveofgreatpain（alsoindirect

resultsofmuscularcontraction），wemaystillseeintheclenchingofthe

hands，theknittingofthebrows，andthesettingoftheteeth，thatthe

bodilyactionsexcitedareasgreat，thoughlessobtrusiveintheirresults。

Ifwetakeemotionsinsteadofsensations，wefindthecorrelationandequivalence

similarlysuggested。emotionsofmoderateintensity，likesensationsofmoderate

intensity，generatelittlebeyondexcitementoftheheartandvascularsystem，

joinedsometimeswithincreasedactionofglandularorgans。Butastheemotions

riseinstrength，themusclesoftheface，body，andlimbs，begintomove。

Ofexamplesmaybementionedthefrowns，dilatednostrils，andstampings

ofanger;thecontractedbrows，andwrunghands，ofgrief;thelaughsand

leapsofjoy;thefranticstrugglesofterrorordespair。Passingovercases

inwhichextremeagitationcausesfainting，weseethatwhateverbethekind

ofemotion，thereisamanifestrelationbetweenitsamount，andtheamount

ofmuscularactioninduced，fromthefidgettinessofimpatienceuptothe

almostconvulsivemovementsaccompanyinggreatmentalagony。Totheseseveral

ordersofevidencemustbejoinedthefurtherorder，thatbetweenfeelings

andthosevoluntarymotionswhichresultfromthem，therecomesthesensation

ofmusculartension，standinginmanifestcorrelationwithboth——acorrelation

thatisdistinctlyquantitative:thesenseofstrainvarying，otherthingsequal，directlyasthequantityofmomentumgenerated。§71a。Butnow，revertingtothecautionwhichprecededthesetwo

paragraphs，wehavetonote，first，thatthefactsdonotprovetransformation

offeelingintomotionbutonlyacertainconstantratiobetweenfeeling

andmotion;andthenwehavefurthertonotethatwhatseemsadirectquantitative

correlationisillusory。Forexample，ticklingisfollowedbyalmostuncontrollable

movementsofthelimbs;butobviouslythereisnoproportionbetweenthe

amountofforceappliedtothesurfaceandtheamountoffeelingortheamount

ofmotion:ratherthereisaninverseproportion，forwhilearoughtouch

doesnotproducetheeffectagentleonedoes。Evenwhenitisrecognized

thatthefeelingisnotthecorrelateoftheexternaltouchingactionbut

ofadisturbanceincertainterminaltactilestructures，itstillremains

demonstrablethatthereisnonecessaryrelationbetweentheamountofsuch

disturbanceandtheamountoffeelingproduced;forundersomeconditions

muscularmotionresultswithouttheintercalationofanyfeeling。Whenthe

spinalcordhasbeensoinjuredastocutoffallnervouscommunicationbetween

thelowerpartofthebodyandthebrain，ticklingthesoleofthefootproduces

convulsionofthelegmoreviolentthanitwoulddowereitaccompaniedby

sensation:thereisareflextransmissionofthestimulusandgenesisof

motionwithoutpassagethroughconsciousness。Casesofanotherclassshow

thatbetweencentralfeelingsoremotionsandthemuscularmovementsthey

initiatetherearenofixedratios:instancethesenseofeffortfeltin

makingasmallmovementbyonewhoisexhausted，ortheinabilityofanpatient

toraisealimbfromthebedhoweverstrongthedesiretodoit。Sothat

neitherthefeelingsperipherallyinitiatednorthosecentrallyinitiated，

thoughtheyarecorrelatedwithmotions，arequantitativelycorrelated。Even

stillmoremanifestbecomesthelackofdirectrelation，eitherqualitative

orquantitative，betweenouterstimuliandinnerfeelings，orbetweensuch

innerfeelingsandmuscularmotions，whenwecontemplatethecomplexkinds

ofmentalprocesses。Theemotionsandactionsofamanwhohasbeeninsulted

areclearlynotequivalentsofthesensationsproducedbythewordsinhis

earsforthesamewordsotherwisearranged，wouldnothavecausedthem。The

thingsaidbearstothementalactionitexcites，muchthesamerelation

thatthepullingofatriggerbearstothesubsequentexplosion——doesnot

producethepowerbutmerelyliberatesit。Whence，then，arisesthisimmenseamountofnervousenergywhichawhisperoraglancemaycallforth？Evidentlyweshallgoutterlywrongiftheproblemofthetransformation

andequivalenceofforcesisdealtwithasthoughanorganismweresimple

andpassiveinsteadofbeingcomplexandactive。Inthelivingbodythere

arealreadygoingonmultitudinoustransformationsofenergyveryvarious

intheirnatures，andbetweenanyphysicalactionfillingonitandanymotion

whichfollows，thereareintercalatednumerouschangesofkindandquantity。