a history of science-2-第14部分

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hrough　the　lens。　The　combination　of　lenses　he　employed　is　that　still　used　in　the　construction　of　opera…glasses；　the　Germans　still　call　such　a　combination　a　Dutch　telescope。　Doubtless　a　large　number　of　experimenters　took　the　matter　up　and　the　fame　of　the　new　instrument　spread　rapidly　abroad。　Galileo；　down　in　Italy；　heard　rumors　of　this　remarkable　contrivance；　through　the　use　of　which　it　was　said　〃distant　objects　might　be　seen　as　clearly　as　those　near　at　hand。〃　He　at　once　set　to　work　to　construct　for　himself　a　similar　instrument；　and　his　efforts　were　so　far　successful　that　at　first　he　〃saw　objects　three　times　as　near　and　nine　times　enlarged。〃　Continuing　his　efforts；　he　presently　so　improved　his　glass　that　objects　were　enlarged　almost　a　thousand　times　and　made　to　appear　thirty　times　nearer　than　when　seen　with　the　naked　eye。　Naturally　enough；　Galileo　turned　this　fascinating　instrument　towards　the　skies；　and　he　was　almost　immediately　rewarded　by　several　startling　discoveries。　At　the　very　outset；　his　magnifying…glass　brought　to　view　a　vast　number　of　stars　that　are　invisible　to　the　naked　eye；　and　enabled　the　observer　to　reach　the　conclusion　that　the　hazy　light　of　the　Milky　Way　is　merely　due　to　the　aggregation　of　a　vast　number　of　tiny　stars。　Turning　his　telescope　towards　the　moon；　Galileo　found　that　body　rough　and　earth…like　in　contour；　its　surface　covered　with　mountains；　whose　height　could　be　approximately　measured　through　study　of　their　shadows。　This　was　disquieting；　because　the　current　Aristotelian　doctrine　supposed　the　moon；　in　common　with　the　planets；　to　be　a　perfectly　spherical；　smooth　body。　The　metaphysical　idea　of　a　perfect　universe　was　sure　to　be　disturbed　by　this　seemingly　rough　workmanship　of　the　moon。　Thus　far；　however；　there　was　nothing　in　the　observations　of　Galileo　to　bear　directly　upon　the　Copernican　theory；　but　when　an　inspection　was　made　of　the　planets　the　case　was　quite　different。　With　the　aid　of　his　telescope；　Galileo　saw　that　Venus；　for　example；　passes　through　phases　precisely　similar　to　those　of　the　moon；　due；　of　course；　to　the　same　cause。　Here；　then；　was　demonstrative　evidence　that　the　planets　are　dark　bodies　reflecting　the　light　of　the　sun；　and　an　explanation　was　given　of　the　fact；　hitherto　urged　in　opposition　to　the　Copernican　theory；　that　the　inferior　planets　do　not　seem　many　times　brighter　when　nearer　the　earth　than　when　in　the　most　distant　parts　of　their　orbits；　the　explanation　being；　of　course；　that　when　the　planets　are　between　the　earth　and　the　sun　only　a　small　portion　of　their　illumined　surfaces　is　visible　from　the　earth。　On　inspecting　the　planet　Jupiter；　a　still　more　striking　revelation　was　made；　as　four　tiny　stars　were　observed　to　occupy　an　equatorial　position　near　that　planet；　and　were　seen；　when　watched　night　after　night；　to　be　circling　about　the　planet；　precisely　as　the　moon　circles　about　the　earth。　Here；　obviously；　was　a　miniature　solar　systema　tangible　object…lesson　in　the　Copernican　theory。　In　honor　of　the　ruling　Florentine　house　of　the　period；　Galileo　named　these　moons　of　Jupiter；　Medicean　stars。　Turning　attention　to　the　sun　itself；　Galileo　observed　on　the　surface　of　that　luminary　a　spot　or　blemish　which　gradually　changed　its　shape；　suggesting　that　changes　were　taking　place　in　the　substance　of　the　sunchanges　obviously　incompatible　with　the　perfect　condition　demanded　by　the　metaphysical　theorists。　But　however　disquieting　for　the　conservative；　the　sun's　spots　served　a　most　useful　purpose　in　enabling　Galileo　to　demonstrate　that　the　sun　itself　revolves　on　its　axis；　since　a　given　spot　was　seen　to　pass　across　the　disk　and　after　disappearing　to　reappear　in　due　course。　The　period　of　rotation　was　found　to　be　about　twenty…four　days。　It　must　be　added　that　various　observers　disputed　priority　of　discovery　of　the　sun's　spots　with　Galileo。　Unquestionably　a　sun…spot　had　been　seen　by　earlier　observers；　and　by　them　mistaken　for　the　transit　of　an　inferior　planet。　Kepler　himself　had　made　this　mistake。　Before　the　day　of　the　telescope；　he　had　viewed　the　image　of　the　sun　as　thrown　on　a　screen　in　a　camera…obscura；　and　had　observed　a　spot　on　the　disk　which　be　interpreted　as　representing　the　planet　Mercury；　but　which；　as　is　now　known；　must　have　been　a　sun…spot；　since　the　planetary　disk　is　too　small　to　have　been　revealed　by　this　method。　Such　observations　as　these；　however　interesting；　cannot　be　claimed　as　discoveries　of　the　sun…spots。　It　is　probable；　however；　that　several　discoverers　（notably　Johann　Fabricius）　made　the　telescopic　observation　of　the　spots；　and　recognized　them　as　having　to　do　with　the　sun's　surface；　almost　simultaneously　with　Galileo。　One　of　these　claimants　was　a　Jesuit　named　Scheiner；　and　the　jealousy　of　this　man　is　said　to　have　had　a　share　in　bringing　about　that　persecution　to　which　we　must　now　refer。　There　is　no　more　famous　incident　in　the　history　of　science　than　the　heresy　trial　through　which　Galileo　was　led　to　the　nominal　renunciation　of　his　cherished　doctrines。　There　is　scarcely　another　incident　that　has　been　commented　upon　so　variously。　Each　succeeding　generation　has　put　its　own　interpretation　on　it。　The　facts；　however；　have　been　but　little　questioned。　It　appears　that　in　the　year　1616　the　church　became　at　last　aroused　to　the　implications　of　the　heliocentric　doctrine　of　the　universe。　Apparently　it　seemed　clear　to　the　church　authorities　that　the　authors　of　the　Bible　believed　the　world　to　be　immovably　fixed　at　the　centre　of　the　universe。　Such；　indeed；　would　seem　to　be　the　natural　inference　from　various　familiar　phrases　of　the　Hebrew　text；　and　what　we　now　know　of　the　status　of　Oriental　science　in　antiquity　gives　full　warrant　to　this　interpretation。　There　is　no　reason　to　suppose　that　the　conception　of　the　subordinate　place　of　the　world　in　the　solar　system　had　ever　so　much　as　occurred；　even　as　a　vague　speculation；　to　the　authors　of　Genesis。　In　common　with　their　contemporaries；　they　believed　the　earth　to　be　the　all…important　body　in　the　universe；　and　the　sun　a　luminary　placed　in　the　sky　for　the　sole　purpose　of　giving　light　to　the　earth。　There　is　nothing　strange；　nothing　anomalous；　in　this　view；　it　merely　reflects　the　current　notions　of　Oriental　peoples　in　antiquity。　What　is　strange　and　anomalous　is　the　fact　that　the　Oriental　dreamings　thus　expressed　could　have　been　supposed　to　represent　the　acme　of　scientific　knowledge。　Yet　such　a　hold　had　these　writings　taken　upon　the　Western　world　that　not　even　a　Galileo　dared　contradict　them　openly；　and　when　the　church　fathers　gravely　declared　the　heliocentric　theory　necessarily　false；　because　contradictory　to　Scripture；　there　were　probably　few　people　in　Christendom　whose　mental　attitude　would　permit　them　justly　to　appreciate　the　humor　of　such　a　pronouncement。　And；　indeed；　if　here　and　there　a　man　might　have　risen　to　such　an　appreciation；　there　were　abundant　reasons　for　the　repression　of　the　impulse；　for　there　was　nothing　humorous　about　the　response　with　which　the　authorities　of　the　time　were　wont　to　meet　the　expression　of　iconoclastic　opinions。　The　burning　at　the　stake　of　Giordano　Bruno；　in　the　year　1600；　was；　for　example；　an　object…lesson　well　calculated　to　restrain　the　enthusiasm　of　other　similarly　minded　teachers。　Doubtless　it　was　such　considerations　that　explained　the　relative　silence　of　the　champions　of　the　Copernican　theory；　accounting　for　the　otherwise　inexplicable　fact　that　about　eighty　years　elapsed　after　the　death　of　Copernicus　himself　before　a　single　text…book　expounded　his　theory。　The　text…book　which　then　appeared；　under　date　of　1622；　was　written　by　the　famous　Kepler；　who　perhaps　was　shielded　in　a　measure　from　the　papal　consequences　of　such　hardihood　by　the　fact　of　residence　in　a　Protestant　country。　Not　that　the　Protestants　of　the　time　favored　the　heliocentric　doctrinewe　have　already　quoted　Luther　in　an　adverse　sensebut　of　course　it　was　characteristic　of　the　Reformation　temper　to　oppose　any　papal　pronouncement；　hence　the　ultramontane　declaration　of　1616　may　indirectly　have　aided　the　doctrine　which　it　attacked；　by　making　that　doctrine　less　obnoxious　to　Lutheran　eyes。　Be　that　as　it　may；　the　work　of　Kepler　brought　its　author　into　no　direct　conflict　with　the　authorities。　But　the　result　was　quite　different　when；　in　1632；　Galileo　at　last　broke　silence　and　gave　the　world；　under　cover　of　the　form　of　dialogue；　an　elaborate　exposition　of　the　Copernican　theory。　Galileo；　it　must　be　explained；　had　previously　been　warned　to　keep　silent　on　the　subject；　hence　his　publication　doubly　offended　the　authorities。　To　be　sure；　he　could　reply　that　his　dialogue　introduced　a　champion　of　the　Ptolemaic　system　to　dispute　with　the　upholder　of　the　opposite　view；　and　that；　both　views　being　presented　with　full　array　of　argument；　the　reader　was　left　to　reach　a　verdict　for　himself；　the　author　having　nowhere　pointedly　expressed　an　opinion。　But　such　an　argument；　of　course；　was　specious；　for　no　one　who　read　the　dialogue　could　be　in　doubt　as　to　the　opinion　of　the　author。　Moreover；　it　was　hinted　that　Simplicio；　the　character　who　upheld　the　Ptolemaic　doctrine　and　who　was　everywhere　worsted　in　the　argument；　was　intended　to　represent　the　pope　himselfa　suggestion　which　probably　did　no　good　to　Galileo's　cause。　The　character　of　Galileo's　artistic　presentation　may　best　be　judged　from　an　example；　illustrating　the　vigor