a history of science-2-第37节

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l　library　at　Berlin。　In　his　experiments　with　his　air…pump　he　discovered　many　things　regarding　the　action　of　gases；　among　others；　that　animals　cannot　live　in　a　vacuum。　He　invented　the　anemoscope　and　the　air…balance；　and　being　thus　enabled　to　weight　the　air　and　note　the　changes　that　preceded　storms　and　calms；　he　was　able　still　further　to　dumfound　his　wondering　fellow…Magde…burgers　by　more　or　less　accurate　predictions　about　the　weather。　Von　Guericke　did　not　accept　Gilbert's　theory　that　the　earth　was　a　great　magnet；　but　in　his　experiments　along　lines　similar　to　those　pursued　by　Gilbert；　he　not　only　invented　the　first　electrical　machine；　but　discovered　electrical　attraction　and　repulsion。　The　electrical　machine　which　he　invented　consisted　of　a　sphere　of　sulphur　mounted　on　an　iron　axis　to　imitate　the　rotation　of　the　earth；　and　which；　when　rubbed；　manifested　electrical　reactions。　When　this　globe　was　revolved　and　stroked　with　the　dry　hand　it　was　found　that　it　attached　to　it　〃all　sorts　of　little　fragments；　like　leaves　of　gold；　silver；　paper；　etc。〃　〃Thus　this　globe；〃　he　says；　〃when　brought　rather　near　drops　of　water　causes　them　to　swell　and　puff　up。　It　likewise　attracts　air；　smoke；　etc。〃＇9＇　Before　the　time　of　Guericke's　demonstrations；　Cabaeus　had　noted　that　chaff　leaped　back　from　an　〃electric；〃　but　he　did　not　interpret　the　phenomenon　as　electrical　repulsion。　Von　Guericke；　however；　recognized　it　as　such；　and　refers　to　it　as　what　he　calls　〃expulsive　virtue。〃　〃Even　expulsive　virtue　is　seen　in　this　globe；〃　he　says；　〃for　it　not　only　attracts；　but　also　REPELS　again　from　itself　little　bodies　of　this　sort；　nor　does　it　receive　them　until　they　have　touched　something　else。〃　It　will　be　observed　from　this　that　he　was　very　close　to　discovering　the　discharge　of　the　electrification　of　attracted　bodies　by　contact　with　some　other　object；　after　which　they　are　reattracted　by　the　electric。　He　performed　a　most　interesting　experiment　with　his　sulphur　globe　and　a　feather；　and　in　doing　so　came　near　anticipating　Benjamin　Franklin　in　his　discovery　of　the　effects　of　pointed　conductors　in　drawing　off　the　discharge。　Having　revolved　and　stroked　his　globe　until　it　repelled　a　bit　of　down；　he　removed　the　globe　from　its　rack　and　advancing　it　towards　the　now　repellent　down；　drove　it　before　him　about　the　room。　In　this　chase　he　observed　that　the　down　preferred　to　alight　against　〃the　points　of　any　object　whatsoever。〃　He　noticed　that　should　the　down　chance　to　be　driven　within　a　few　inches　of　a　lighted　candle；　its　attitude　towards　the　globe　suddenly　changed；　and　instead　of　running　away　from　it；　it　now　〃flew　to　it　for　protection〃　the　charge　on　the　down　having　been　dissipated　by　the　hot　air。　He　also　noted　that　if　one　face　of　a　feather　had　been　first　attracted　and　then　repelled　by　the　sulphur　ball；　that　the　surface　so　affected　was　always　turned　towards　the　globe；　so　that　if　the　positions　of　the　two　were　reversed；　the　sides　of　the　feather　reversed　also。　Still　another　important　discovery；　that　of　electrical　conduction；　was　made　by　Von　Guericke。　Until　his　discovery　no　one　had　observed　the　transference　of　electricity　from　one　body　to　another；　although　Gilbert　had　some　time　before　noted　that　a　rod　rendered　magnetic　at　one　end　became　so　at　the　other。　Von　Guericke's　experiments　were　made　upon　a　linen　thread　with　his　sulphur　globe；　which；　he　says；　〃having　been　previously　excited　by　rubbing；　can　exercise　likewise　its　virtue　through　a　linen　thread　an　ell　or　more　long；　and　there　attract　something。〃　But　this　discovery；　and　his　equally　important　one　that　the　sulphur　ball　becomes　luminous　when　rubbed；　were　practically　forgotten　until　again　brought　to　notice　by　the　discoveries　of　Francis　Hauksbee　and　Stephen　Gray　early　in　the　eighteenth　century。　From　this　we　may　gather　that　Von　Guericke　himself　did　not　realize　the　import　of　his　discoveries；　for　otherwise　he　would　certainly　have　carried　his　investigations　still　further。　But　as　it　was　he　turned　his　attention　to　other　fields　of　research。

ROBERT　HOOKE　A　slender；　crooked；　shrivelled…limbed；　cantankerous　little　man；　with　dishevelled　hair　and　haggard　countenance；　bad…tempered　and　irritable；　penurious　and　dishonest；　at　least　in　his　claims　for　priority　in　discoveriesthis　is　the　picture　usually　drawn；　alike　by　friends　and　enemies；　of　Robert　Hooke　（1635…1703）；　a　man　with　an　almost　unparalleled　genius　for　scientific　discoveries　in　almost　all　branches　of　science。　History　gives　few　examples　so　striking　of　a　man　whose　really　great　achievements　in　science　would　alone　have　made　his　name　immortal；　and　yet　who　had　the　pusillanimous　spirit　of　a　charlatanan　almost　insane　mania；　as　it　seemsfor　claiming　the　credit　of　discoveries　made　by　others。　This　attitude　of　mind　can　hardly　be　explained　except　as　a　mania：　it　is　certainly　more　charitable　so　to　regard　it。　For　his　own　discoveries　and　inventions　were　so　numerous　that　a　few　more　or　less　would　hardly　have　added　to　his　fame；　as　his　reputation　as　a　philosopher　was　well　established。　Admiration　for　his　ability　and　his　philosophical　knowledge　must　always　be　marred　by　the　recollection　of　his　arrogant　claims　to　the　discoveries　of　other　philosophers。　It　seems　pretty　definitely　determined　that　Hooke　should　be　credited　with　the　invention　of　the　balance…spring　for　regulating　watches；　but　for　a　long　time　a　heated　controversy　was　waged　between　Hooke　and　Huygens　as　to　who　was　the　real　inventor。　It　appears　that　Hooke　conceived　the　idea　of　the　balance…spring；　while　to　Huygens　belongs　the　credit　of　having　adapted　the　COILED　spring　in　a　working　model。　He　thus　made　practical　Hooke's　conception；　which　is　without　value　except　as　applied　by　the　coiled　spring；　but；　nevertheless；　the　inventor；　as　well　as　the　perfector；　should　receive　credit。　In　this　controversy；　unlike　many　others；　the　blame　cannot　be　laid　at　Hooke's　door。　Hooke　was　the　first　curator　of　the　Royal　Society；　and　when　anything　was　to　be　investigated；　usually　invented　the　mechanical　devices　for　doing　so。　Astronomical　apparatus；　instruments　for　measuring　specific　weights；　clocks　and　chronometers；　methods　of　measuring　the　velocity　of　falling　bodies；　freezing　and　boiling　points；　strength　of　gunpowder；　magnetic　instrumentsin　short；　all　kinds　of　ingenious　mechanical　devices　in　all　branches　of　science　and　mechanics。　It　was　he　who　made　the　famous　air…pump　of　Robert　Boyle；　based　on　Boyle's　plans。　Incidentally；　Hooke　claimed　to　be　the　inventor　of　the　first　air…pump　himself；　although　this　claim　is　now　entirely　discredited。　Within　a　period　of　two　years　he　devised　no　less　than　thirty　different　methods　of　flying；　all　of　which；　of　course；　came　to　nothing；　but　go　to　show　the　fertile　imagination　of　the　man；　and　his　tireless　energy。　He　experimented　with　electricity　and　made　some　novel　suggestions　upon　the　difference　between　the　electric　spark　and　the　glow；　although　on　the　whole　his　contributions　in　this　field　are　unimportant。　He　also　first　pointed　out　that　the　motions　of　the　heavenly　bodies　must　be　looked　upon　as　a　mechanical　problem；　and　was　almost　within　grasping　distance　of　the　exact　theory　of　gravitation；　himself　originating　the　idea　of　making　use　of　the　pendulum　in　measuring　gravity。　Likewise；　he　first　proposed　the　wave　theory　of　light；　although　it　was　Huygens　who　established　it　on　its　present　foundation。　Hooke　published；　among　other　things；　a　book　of　plates　and　descriptions　of　his　Microscopical　Observations；　which　gives　an　idea　of　the　advance　that　had　already　been　made　in　microscopy　in　his　time。　Two　of　these　plates　are　given　here；　which；　even　in　this　age　of　microscopy；　are　both　interesting　and　instructive。　These　plates　are　made　from　prints　of　Hooke's　original　copper　plates；　and　show　that　excellent　lenses　were　made　even　at　that　time。　They　illustrate；　also；　how　much　might　have　been　accomplished　in　the　field　of　medicine　if　more　attention　had　been　given　to　microscopy　by　physicians。　Even　a　century　later；　had　physicians　made　better　use　of　their　microscopes；　they　could　hardly　have　overlooked　such　an　easily　found　parasite　as　the　itch　mite；　which　is　quite　as　easily　detected　as　the　cheese　mite；　pictured　in　Hooke's　book。　In　justice　to　Hooke；　and　in　extenuation　of　his　otherwise　inexcusable　peculiarities　of　mind；　it　should　be　remembered　that　for　many　years　he　suffered　from　a　painful　and　wasting　disease。　This　may　have　affected　his　mental　equilibrium；　without　appreciably　affecting　his　ingenuity。　In　his　own　time　this　condition　would　hardly　have　been　considered　a　disease；　but　to…day；　with　our　advanced　ideas　as　to　mental　diseases；　we　should　be　more　inclined　to　ascribe　his　unfortunate　attitude　of　mind　to　a　pathological　condition；　rather　than　to　any　manifestation　of　normal　mentality。　From　this　point　of　view　his　mental　deformity　seems　not　unlike　that　of　Cavendish's；　later；　except　that　in　the　case　of　Cavendish　it　manifested　itself　as　an　abnormal　sensitiveness　instead　of　an　abnormal　irritability。

CHRISTIAN　HUYGENS　If　for　nothing　else；　the　world　is　indebted　to　the　man　who　invented　the　pendulum　clock；　Christian　Huygens　（1629…1695）；　of　the　Hague；　inventor；　mathematician；　mechanician；　astronomer；　and　physicist。　Huygens　was　the　descendant　of　a　noble　and　distinguished　family；　his　father；　Sir　Constantine　Huygens；　being　a　well…known　poet　and　diplomatist。　Early　in　life　young　Huygens　began　his　career　in　the　legal　profession；　comp