a history of science-1-第48节

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s　that　the　earth　is　the　fixed　centre　of　the　solar　system；　and　that　the　stars　and　planets　revolve　about　it　in　twenty…four　hours；　the　earth　being；　of　course；　spherical。　It　was　not　to　be　expected　that　Ptolemy　should　have　adopted　the　heliocentric　idea　of　Aristarchus。　Yet　it　is　much　to　be　regretted　that　he　failed　to　do　so；　since　the　deference　which　was　accorded　his　authority　throughout　the　Middle　Ages　would　doubtless　have　been　extended　in　some　measure　at　least　to　this　theory　as　well；　had　he　championed　it。　Contrariwise；　his　unqualified　acceptance　of　the　geocentric　doctrine　sufficed　to　place　that　doctrine　beyond　the　range　of　challenge。　The　Almagest　treats　of　all　manner　of　astronomical　problems；　but　the　feature　of　it　which　gained　it　widest　celebrity　was　perhaps　that　which　has　to　do　with　eccentrics　and　epicycles。　This　theory　was；　of　course；　but　an　elaboration　of　the　ideas　of　Hipparchus；　but；　owing　to　the　celebrity　of　the　expositor；　it　has　come　to　be　spoken　of　as　the　theory　of　Ptolemy。　We　have　sufficiently　detailed　the　theory　in　speaking　of　Hipparchus。　It　should　be　explained；　however；　that；　with　both　Hipparchus　and　Ptolemy；　the　theory　of　epicycles　would　appear　to　have　been　held　rather　as　a　working　hypothesis　than　as　a　certainty；　so　far　as　the　actuality　of　the　minor　spheres　or　epicycles　is　concerned。　That　is　to　say；　these　astronomers　probably　did　not　conceive　either　the　epicycles　or　the　greater　spheres　as　constituting　actual　solid　substances。　Subsequent　generations；　however；　put　this　interpretation　upon　the　theory；　conceiving　the　various　spheres　as　actual　crystalline　bodies。　It　is　difficult　to　imagine　just　how　the　various　epicycles　were　supposed　to　revolve　without　interfering　with　the　major　spheres；　but　perhaps　this　is　no　greater　difficulty　than　is　presented　by　the　alleged　properties　of　the　ether；　which　physicists　of　to…day　accept　as　at　least　a　working　hypothesis。　We　shall　see　later　on　how　firmly　the　conception　of　concentric　crystalline　spheres　was　held　to；　and　that　no　real　challenge　was　ever　given　that　theory　until　the　discovery　was　made　that　comets　have　an　orbit　that　must　necessarily　intersect　the　spheres　of　the　various　planets。　Ptolemy's　system　of　geography　in　eight　books；　founded　on　that　of　Marinus　of　Tyre；　was　scarcely　less　celebrated　throughout　the　Middle　Ages　than　the　Almagest。　It　contained　little；　however；　that　need　concern　us　here；　being　rather　an　elaboration　of　the　doctrines　to　which　we　have　already　sufficiently　referred。　None　of　Ptolemy's　original　manuscripts　has　come　down　to　us；　but　there　is　an　alleged　fifth…century　manuscript　attributed　to　Agathadamon　of　Alexandria　which　has　peculiar　interest　because　it　contains　a　series　of　twenty…seven　elaborately　colored　maps　that　are　supposed　to　be　derived　from　maps　drawn　up　by　Ptolemy　himself。　In　these　maps　the　sea　is　colored　green；　the　mountains　red　or　dark　yellow；　and　the　land　white。　Ptolemy　assumed　that　a　degree　at　the　equator　was　500　stadia　instead　of　604　stadia　in　length。　We　are　not　informed　as　to　the　grounds　on　which　this　assumption　was　made；　but　it　has　been　suggested　that　the　error　was　at　least　partially　instrumental　in　leading　to　one　very　curious　result。　〃Taking　the　parallel　of　Rhodes；〃　says　Donaldson；＇5＇　〃he　calculated　the　longitudes　from　the　Fortunate　Islands　to　Cattigara　or　the　west　coast　of　Borneo　at　180　degrees；　conceiving　this　to　be　one…half　the　circumference　of　the　globe。　The　real　distance　is　only　125　degrees　or　127　degrees；　so　that　his　measurement　is　wrong　by　one　third　of　the　whole；　one…sixth　for　the　error　in　the　measurement　of　a　degree　and　one…sixth　for　the　errors　in　measuring　the　distance　geometrically。　These　errors；　owing　to　the　authority　attributed　to　the　geography　of　Ptolemy　in　the　Middle　Ages；　produced　a　consequence　of　the　greatest　importance。　They　really　led　to　the　discovery　of　America。　For　the　design　of　Columbus　to　sail　from　the　west　of　Europe　to　the　east　of　Asia　was　founded　on　the　supposition　that　the　distance　was　less　by　one　third　than　it　really　was。〃　This　view　is　perhaps　a　trifle　fanciful；　since　there　is　nothing　to　suggest　that　the　courage　of　Columbus　would　have　balked　at　the　greater　distance；　and　since　the　protests　of　the　sailors；　which　nearly　thwarted　his　efforts；　were　made　long　before　the　distance　as　estimated　by　Ptolemy　had　been　covered；　nevertheless　it　is　interesting　to　recall　that　the　great　geographical　doctrines；　upon　which　Columbus　must　chiefly　have　based　his　arguments；　had　been　before　the　world　in　an　authoritative　form　practically　unheeded　for　more　than　twelve　hundred　years；　awaiting　a　champion　with　courage　enough　to　put　them　to　the　test。

GALENTHE　LAST　GREAT　ALEXANDRIAN　There　is　one　other　field　of　scientific　investigation　to　which　we　must　give　brief　attention　before　leaving　the　antique　world。　This　is　the　field　of　physiology　and　medicine。　In　considering　it　we　shall　have　to　do　with　the　very　last　great　scientist　of　the　Alexandrian　school。　This　was　Claudius　Galenus；　commonly　known　as　Galen；　a　man　whose　fame　was　destined　to　eclipse　that　of　all　other　physicians　of　antiquity　except　Hippocrates；　and　whose　doctrines　were　to　have　the　same　force　in　their　field　throughout　the　Middle　Ages　that　the　doctrines　of　Aristotle　had　for　physical　science。　But　before　we　take　up　Galen's　specific　labors；　it　will　be　well　to　inquire　briefly　as　to　the　state　of　medical　art　and　science　in　the　Roman　world　at　the　time　when　the　last　great　physician　of　antiquity　came　upon　the　scene。　The　Romans；　it　would　appear；　had　done　little　in　the　way　of　scientific　discoveries　in　the　field　of　medicine；　but；　nevertheless；　with　their　practicality　of　mind；　they　had　turned　to　better　account　many　more　of　the　scientific　discoveries　of　the　Greeks　than　did　the　discoverers　themselves。　The　practising　physicians　in　early　Rome　were　mostly　men　of　Greek　origin；　who　came　to　the　capital　after　the　overthrow　of　the　Greeks　by　the　Romans。　Many　of　them　were　slaves；　as　earning　money　by　either　bodily　or　mental　labor　was　considered　beneath　the　dignity　of　a　Roman　citizen。　The　wealthy　Romans；　who　owned　large　estates　and　numerous　slaves；　were　in　the　habit　of　purchasing　some　of　these　slave　doctors；　and　thus　saving　medical　fees　by　having　them　attend　to　the　health　of　their　families。　By　the　beginning　of　the　Christian　era　medicine　as　a　profession　had　sadly　degenerated；　and　in　place　of　a　class　of　physicians　who　practised　medicine　along　rational　or　legitimate　lines；　in　the　footsteps　of　the　great　Hippocrates；　there　appeared　great　numbers　of　〃specialists；〃　most　of　them　charlatans；　who　pretended　to　possess　supernatural　insight　in　the　methods　of　treating　certain　forms　of　disease。　These　physicians　rightly　earned　the　contempt　of　the　better　class　of　Romans；　and　were　made　the　object　of　many　attacks　by　the　satirists　of　the　time。　Such　specialists　travelled　about　from　place　to　place　in　much　the　same　manner　as　the　itinerant　〃Indian　doctors〃　and　〃lightning　tooth…extractors〃　do　to…day。　Eye…doctors　seem　to　have　been　particularly　numerous；　and　these　were　divided　into　two　classes；　eye…surgeons　and　eye…doctors　proper。　The　eye…surgeon　performed　such　operations　as　cauterizing　for　ingrowing　eyelashes　and　operating　upon　growths　about　the　eyes；　while　the　eye…doctors　depended　entirely　upon　salves　and　lotions。　These　eye…salves　were　frequently　stamped　with　the　seal　of　the　physician　who　compounded　them；　something　like　two　hundred　of　these　seals　being　still　in　existence。　There　were　besides　these　quacks；　however；　reputable　eye…doctors　who　must　have　possessed　considerable　skill　in　the　treatment　of　certain　ophthalmias。　Among　some　Roman　surgical　instruments　discovered　at　Rheims　were　found　also　some　drugs　employed　by　ophthalmic　surgeons；　and　an　analysis　of　these　show　that　they　contained；　among　other　ingredients；　some　that　are　still　employed　in　the　treatment　of　certain　affections　of　the　eye。　One　of　the　first　steps　taken　in　recognition　of　the　services　of　physicians　was　by　Julius　Caesar；　who　granted　citizenship　to　all　physicians　practising　in　Rome。　This　was　about　fifty　years　before　the　Christian　era；　and　from　that　time　on　there　was　a　gradual　improvement　in　the　attitude　of　the　Romans　towards　the　members　of　the　medical　profession。　As　the　Romans　degenerated　from　a　race　of　sturdy　warriors　and　became　more　and　more　depraved　physically；　the　necessity　for　physicians　made　itself　more　evident。　Court　physicians；　and　physicians…in…ordinary；　were　created　by　the　emperors；　as　were　also　city　and　district　physicians。　In　the　year　133　A。D。　Hadrian　granted　immunity　from　taxes　and　military　service　to　physicians　in　recognition　of　their　public　services。　The　city　and　district　physicians；　known　as　the　archiatri　populaires；　treated　and　cared　for　the　poor　without　remuneration；　having　a　position　and　salary　fixed　by　law　and　paid　them　semi…annually。　These　were　honorable　positions；　and　the　archiatri　were　obliged　to　give　instruction　in　medicine；　without　pay；　to　the　poor　students。　They　were　allowed　to　receive　fees　and　donations　from　their　patients；　but　not；　however；　until　the　danger　from　the　malady　was　past。　Special　laws　were　enacted　to　protect　them；　and　any　person　subjecting　them　to　an　insult　was　liable　to　a　fine　〃not　exceeding　one　thousand　pounds。〃　An　example　of　Roman　practicality　is　shown　in　the　method　of　treating　hemorrhage；　as　described　by　Aulus　Cornelius　Celsus　（53　B。C。　to　7　A。D。）。　Hippocrates　and　Hippoc