a history of science-2-第38章

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tions　by　Galileo；　and　more　recently　the　discovery　of　the　circulation　of　the　blood　by　Harvey。　This　last　came　as　a　revelation　to　scientists；　reducing　this　seemingly　occult　process；　as　it　did；　to　the　field　of　mechanical　phenomena。　The　same　mechanical　laws　that　governed　the　heavenly　bodies；　as　shown　by　Galileo；　governed　the　action　of　the　human　heart；　and；　for　aught　any　one　knew；　every　part　of　the　body；　and　even　the　mind　itself。　Having　once　conceived　this　idea；　Descartes　began　a　series　of　dissections　and　experiments　upon　the　lower　animals；　to　find；　if　possible；　further　proof　of　this　general　law。　To　him　the　human　body　was　simply　a　machine；　a　complicated　mechanism；　whose　functions　were　controlled　just　as　any　other　piece　of　machinery。　He　compared　the　human　body　to　complicated　machinery　run　by　water…falls　and　complicated　pipes。　〃The　nerves　of　the　machine　which　I　am　describing；〃　he　says；　〃may　very　well　be　compared　to　the　pipes　of　these　waterworks；　its　muscles　and　its　tendons　to　the　other　various　engines　and　springs　which　seem　to　move　them；　its　animal　spirits　to　the　water　which　impels　them；　of　which　the　heart　is　the　fountain；　while　the　cavities　of　the　brain　are　the　central　office。　Moreover；　respiration　and　other　such　actions　as　are　natural　and　usual　in　the　body；　and　which　depend　on　the　course　of　the　spirits；　are　like　the　movements　of　a　clock；　or　a　mill；　which　may　be　kept　up　by　the　ordinary　flow　of　water。〃＇3＇　In　such　passages　as　these　Descartes　anticipates　the　ideas　of　physiology　of　the　present　time。　He　believed　that　the　functions　are　performed　by　the　various　organs　of　the　bodies　of　animals　and　men　as　a　mechanism；　to　which　in　man　was　added　the　soul。　This　soul　he　located　in　the　pineal　gland；　a　degenerate　and　presumably　functionless　little　organ　in　the　brain。　For　years　Descartes's　idea　of　the　function　of　this　gland　was　held　by　many　physiologists；　and　it　was　only　the　introduction　of　modern　high…power　microscopy　that　reduced　this　also　to　a　mere　mechanism；　and　showed　that　it　is　apparently　the　remains　of　a　Cyclopean　eye　once　common　to　man's　remote　ancestors。　Descartes　was　the　originator　of　a　theory　of　the　movements　of　the　universe　by　a　mechanical　processthe　Cartesian　theory　of　vorticeswhich　for　several　decades　after　its　promulgation　reigned　supreme　in　science。　It　is　the　ingenuity　of　this　theory；　not　the　truth　of　its　assertions；　that　still　excites　admiration；　for　it　has　long　since　been　supplanted。　It　was　certainly　the　best　hitherto　advancedthe　best　〃that　the　observations　of　the　age　admitted；〃　according　to　D'Alembert。　According　to　this　theory　the　infinite　universe　is　full　of　matter；　there　being　no　such　thing　as　a　vacuum。　Matter；　as　Descartes　believed；　is　uniform　in　character　throughout　the　entire　universe；　and　since　motion　cannot　take　place　in　any　part　of　a　space　completely　filled；　without　simultaneous　movement　in　all　other　parts；　there　are　constant　more　or　less　circular　movements；　vortices；　or　whirlpools　of　particles；　varying；　of　course；　in　size　and　velocity。　As　a　result　of　this　circular　movement　the　particles　of　matter　tend　to　become　globular　from　contact　with　one　another。　Two　species　of　matter　are　thus　formed；　one　larger　and　globular；　which　continue　their　circular　motion　with　a　constant　tendency　to　fly　from　the　centre　of　the　axis　of　rotation；　the　other　composed　of　the　clippings　resulting　from　the　grinding　process。　These　smaller　〃filings〃　from　the　main　bodies；　becoming　smaller　and　smaller；　gradually　lose　their　velocity　and　accumulate　in　the　centre　of　the　vortex。　This　collection　of　the　smaller　matter　in　the　centre　of　the　vortex　constitutes　the　sun　or　star；　while　the　spherical　particles　propelled　in　straight　lines　from　the　centre　towards　the　circumference　of　the　vortex　produce　the　phenomenon　of　light　radiating　from　the　central　star。　Thus　this　matter　becomes　the　atmosphere　revolving　around　the　accumulation　at　the　centre。　But　the　small　particles　being　constantly　worn　away　from　the　revolving　spherical　particles　in　the　vortex；　become　entangled　in　their　passage；　and　when　they　reach　the　edge　of　the　inner　strata　of　solar　dust　they　settle　upon　it　and　form　what　we　call　sun…spots。　These　are　constantly　dissolved　and　reformed；　until　sometimes　they　form　a　crust　round　the　central　nucleus。　As　the　expansive　force　of　the　star　diminishes　in　the　course　of　time；　it　is　encroached　upon　by　neighboring　vortices。　If　the　part　of　the　encroaching　star　be　of　a　less　velocity　than　the　star　which　it　has　swept　up；　it　will　presently　lose　its　hold；　and　the　smaller　star　pass　out　of　range；　becoming　a　comet。　But　if　the　velocity　of　the　vortex　into　which　the　incrusted　star　settles　be　equivalent　to　that　of　the　surrounded　vortex；　it　will　hold　it　as　a　captive；　still　revolving　and　〃wrapt　in　its　own　firmament。〃　Thus　the　several　planets　of　our　solar　system　have　been　captured　and　held　by　the　sun…vortex；　as　have　the　moon　and　other　satellites。　But　although　these　new　theories　at　first　created　great　enthusiasm　among　all　classes　of　philosophers　and　scientists；　they　soon　came　under　the　ban　of　the　Church。　While　no　actual　harm　came　to　Descartes　himself；　his　writings　were　condemned　by　the　Catholic　and　Protestant　churches　alike。　The　spirit　of　philosophical　inquiry　he　had　engendered；　however；　lived　on；　and　is　largely　responsible　for　modern　philosophy。　In　many　ways　the　life　and　works　of　Leibnitz　remind　us　of　Bacon　rather　than　Descartes。　His　life　was　spent　in　filling　high　political　positions；　and　his　philosophical　and　scientific　writings　were　by…paths　of　his　fertile　mind。　He　was　a　theoretical　rather　than　a　practical　scientist；　his　contributions　to　science　being　in　the　nature　of　philosophical　reasonings　rather　than　practical　demonstrations。　Had　he　been　able　to　withdraw　from　public　life　and　devote　himself　to　science　alone；　as　Descartes　did；　he　would　undoubtedly　have　proved　himself　equally　great　as　a　practical　worker。　But　during　the　time　of　his　greatest　activity　in　philosophical　fields；　between　the　years　1690　and　1716；　he　was　all　the　time　performing　extraordinary　active　duties　in　entirely　foreign　fields。　His　work　may　be　regarded；　perhaps；　as　doing　for　Germany　in　particular　what　Bacon's　did　for　England　and　the　rest　of　the　world　in　general。　Only　a　comparatively　small　part　of　his　philosophical　writings　concern　us　here。　According　to　his　theory　of　the　ultimate　elements　of　the　universe；　the　entire　universe　is　composed　of　individual　centres；　or　monads。　To　these　monads　he　ascribed　numberless　qualities　by　which　every　phase　of　nature　may　be　accounted。　They　were　supposed　by　him　to　be　percipient；　self…acting　beings；　not　under　arbitrary　control　of　the　deity；　and　yet　God　himself　was　the　original　monad　from　which　all　the　rest　are　generated。　With　this　conception　as　a　basis；　Leibnitz　deduced　his　doctrine　of　pre…established　harmony；　whereby　the　numerous　independent　substances　composing　the　world　are　made　to　form　one　universe。　He　believed　that　by　virtue　of　an　inward　energy　monads　develop　themselves　spontaneously；　each　being　independent　of　every　other。　In　short；　each　monad　is　a　kind　of　deity　in　itselfa　microcosm　representing　all　the　great　features　of　the　macrocosm。　It　would　be　impossible　clearly　to　estimate　the　precise　value　of　the　stimulative　influence　of　these　philosophers　upon　the　scientific　thought　of　their　time。　There　was　one　way；　however；　in　which　their　influence　was　made　very　tangiblenamely；　in　the　incentive　they　gave　to　the　foundation　of　scientific　societies。

SCIENTIFIC　SOCIETIES　At　the　present　time；　when　the　elements　of　time　and　distance　are　practically　eliminated　in　the　propagation　of　news；　and　when　cheap　printing　has　minimized　the　difficulties　of　publishing　scientific　discoveries；　it　is　difficult　to　understand　the　isolated　position　of　the　scientific　investigation　of　the　ages　that　preceded　steam　and　electricity。　Shut　off　from　the　world　and　completely　out　of　touch　with　fellow…laborers　perhaps　only　a　few　miles　away；　the　investigators　were　naturally　seriously　handicapped；　and　inventions　and　discoveries　were　not　made　with　the　same　rapidity　that　they　would　undoubtedly　have　been　had　the　same　men　been　receiving　daily；　weekly；　or　monthly　communications　from　fellow…laborers　all　over　the　world；　as　they　do　to…day。　Neither　did　they　have　the　advantage　of　public　or　semi…public　laboratories；　where　they　were　brought　into　contact　with　othe