a history of science-1-第29章

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dern　times；　but　it　still　excites　the　admiration　of　all　who　examine　it；　and　its　effects　seem　as　paradoxical　as　ever。　Some　other　of　the　mechanisms　of　Archimedes　have　been　made　known　to　successive　generations　of　readers　through　the　pages　of　Polybius　and　Plutarch。　These　are　the　devices　through　which　Archimedes　aided　King　Hiero　to　ward　off　the　attacks　of　the　Roman　general　Marcellus；　who　in　the　course　of　the　second　Punic　war　laid　siege　to　Syracuse。　Plutarch；　in　his　life　of　Marcellus；　describes　the　Roman's　attack　and　Archimedes'　defence　in　much　detail。　Incidentally　he　tells　us　also　how　Archimedes　came　to　make　the　devices　that　rendered　the　siege　so　famous：　〃Marcellus　himself；　with　threescore　galleys　of　five　rowers　at　every　bank；　well　armed　and　full　of　all　sorts　of　artillery　and　fireworks；　did　assault　by　sea；　and　rowed　hard　to　the　wall；　having　made　a　great　engine　and　device　of　battery；　upon　eight　galleys　chained　together；　to　batter　the　wall：　trusting　in　the　great　multitude　of　his　engines　of　battery；　and　to　all　such　other　necessary　provision　as　he　had　for　wars；　as　also　in　his　own　reputation。　But　Archimedes　made　light　account　of　all　his　devices；　as　indeed　they　were　nothing　comparable　to　the　engines　himself　had　invented。　This　inventive　art　to　frame　instruments　and　engines　（which　are　called　mechanical；　or　organical；　so　highly　commended　and　esteemed　of　all　sorts　of　people）　was　first　set　forth　by　Architas；　and　by　Eudoxus：　partly　to　beautify　a　little　the　science　of　geometry　by　this　fineness；　and　partly　to　prove　and　confirm　by　material　examples　and　sensible　instruments；　certain　geometrical　conclusions；　where　of　a　man　cannot　find　out　the　conceivable　demonstrations　by　enforced　reasons　and　proofs。　As　that　conclusion　which　instructeth　one　to　search　out　two　lines　mean　proportional；　which　cannot　be　proved　by　reason　demonstrative；　and　yet　notwithstanding　is　a　principle　and　an　accepted　ground　for　many　things　which　are　contained　in　the　art　of　portraiture。　Both　of　them　have　fashioned　it　to　the　workmanship　of　certain　instruments；　called　mesolabes　or　mesographs；　which　serve　to　find　these　mean　lines　proportional；　by　drawing　certain　curve　lines；　and　overthwart　and　oblique　sections。　But　after　that　Plato　was　offended　with　them；　and　maintained　against　them；　that　they　did　utterly　corrupt　and　disgrace；　the　worthiness　and　excellence　of　geometry；　making　it　to　descend　from　things　not　comprehensible　and　without　body；　unto　things　sensible　and　material；　and　to　bring　it　to　a　palpable　substance；　where　the　vile　and　base　handiwork　of　man　is　to　be　employed：　since　that　time；　I　say；　handicraft；　or　the　art　of　engines；　came　to　be　separated　from　geometry；　and　being　long　time　despised　by　the　philosophers；　it　came　to　be　one　of　the　warlike　arts。　〃But　Archimedes　having　told　King　Hiero；　his　kinsman　and　friend；　that　it　was　possible　to　remove　as　great　a　weight　as　he　would；　with　as　little　strength　as　he　listed　to　put　to　it：　and　boasting　himself　thus　（as　they　report　of　him）　and　trusting　to　the　force　of　his　reasons；　wherewith　he　proved　this　conclusion；　that　if　there　were　another　globe　of　earth；　he　was　able　to　remove　this　of　ours；　and　pass　it　over　to　the　other：　King　Hiero　wondering　to　hear　him；　required　him　to　put　his　device　in　execution；　and　to　make　him　see　by　experience；　some　great　or　heavy　weight　removed；　by　little　force。　So　Archimedes　caught　hold　with　a　book　of　one　of　the　greatest　carects；　or　hulks　of　the　king　（that　to　draw　it　to　the　shore　out　of　the　water　required　a　marvellous　number　of　people　to　go　about　it；　and　was　hardly　to　be　done　so）　and　put　a　great　number　of　men　more　into　her；　than　her　ordinary　burden：　and　he　himself　sitting　alone　at　his　ease　far　off；　without　any　straining　at　all；　drawing　the　end　of　an　engine　with　many　wheels　and　pulleys；　fair　and　softly　with　his　hand；　made　it　come　as　gently　and　smoothly　to　him；　as　it　had　floated　in　the　sea。　The　king　wondering　to　see　the　sight；　and　knowing　by　proof　the　greatness　of　his　art；　be　prayed　him　to　make　him　some　engines；　both　to　assault　and　defend；　in　all　manner　of　sieges　and　assaults。　So　Archimedes　made　him　many　engines；　but　King　Hiero　never　occupied　any　of　them；　because　he　reigned　the　most　part　of　his　time　in　peace　without　any　wars。　But　this　provision　and　munition　of　engines；　served　the　Syracusan's　turn　marvellously　at　that　time：　and　not　only　the　provision　of　the　engines　ready　made；　but　also　the　engineer　and　work…master　himself；　that　had　invented　them。　〃Now　the　Syracusans；　seeing　themselves　assaulted　by　the　Romans；　both　by　sea　and　by　land；　were　marvellously　perplexed；　and　could　not　tell　what　to　say；　they　were　so　afraid：　imagining　it　was　impossible　for　them　to　withstand　so　great　an　army。　But　when　Archimedes　fell　to　handling　his　engines；　and　to　set　them　at　liberty；　there　flew　in　the　air　infinite　kinds　of　shot；　and　marvellous　great　stones；　with　an　incredible　noise　and　force　on　the　sudden；　upon　the　footmen　that　came　to　assault　the　city　by　land；　bearing　down；　and　tearing　in　pieces　all　those　which　came　against　them；　or　in　what　place　soever　they　lighted；　no　earthly　body　being　able　to　resist　the　violence　of　so　heavy　a　weight：　so　that　all　their　ranks　were　marvellously　disordered。　And　as　for　the　galleys　that　gave　assault　by　sea；　some　were　sunk　with　long　pieces　of　timber　like　unto　the　yards　of　ships；　whereto　they　fasten　their　sails；　which　were　suddenly　blown　over　the　walls　with　force　of　their　engines　into　their　galleys；　and　so　sunk　them　by　their　over　great　weight。〃

Polybius　describes　what　was　perhaps　the　most　important　of　these　contrivances；　which　was；　he　tells　us；　〃a　band　of　iron；　hanging　by　a　chain　from　the　beak　of　a　machine；　which　was　used　in　the　following　manner。　The　person　who；　like　a　pilot；　guided　the　beak；　having　let　fall　the　hand；　and　catched　hold　of　the　prow　of　any　vessel；　drew　down　the　opposite　end　of　the　machine　that　was　on　the　inside　of　the　walls。　And　when　the　vessel　was　thus　raised　erect　upon　its　stem；　the　machine　itself　was　held　immovable；　but；　the　chain　being　suddenly　loosened　from　the　beak　by　the　means　of　pulleys；　some　of　the　vessels　were　thrown　upon　their　sides；　others　turned　with　the　bottom　upwards；　and　the　greatest　part；　as　the　prows　were　plunged　from　a　considerable　height　into　the　sea；　were　filled　with　water；　and　all　that　were　on　board　thrown　into　tumult　and　disorder。　〃Marcellus　was　in　no　small　degree　embarrassed；〃　Polybius　continues；　〃when　he　found　himself　encountered　in　every　attempt　by　such　resistance。　He　perceived　that　all　his　efforts　were　defeated　with　loss；　and　were　even　derided　by　the　enemy。　But；　amidst　all　the　anxiety　that　he　suffered；　he　could　not　help　jesting　upon　the　inventions　of　Archimedes。　This　man；　said　he；　employs　our　ships　as　buckets　to　draw　water：　and　boxing　about　our　sackbuts；　as　if　they　were　unworthy　to　be　associated　with　him；　drives　them　from　his　company　with　disgrace。　Such　was　the　success　of　the　siege　on　the　side　of　the　sea。〃　Subsequently；　however；　Marcellus　took　the　city　by　strategy；　and　Archimedes　was　killed；　contrary；　it　is　said；　to　the　express　orders　of　Marcellus。　〃Syracuse　being　taken；〃　says　Plutarch；　〃nothing　grieved　Marcellus　more　than　the　loss　of　Archimedes。　Who；　being　in　his　study　when　the　city　was　taken；　busily　seeking　out　by　himself　the　demonstration　of　some　geometrical　proposition　which　he　had　drawn　in　figure；　and　so　earnestly　occupied　therein；　as　he　neither　saw　nor　heard　any　noise　of　enemies　that　ran　up　and　down　the　city；　and　much　less　knew　it　was　taken：　he　wondered　when　he　saw　a　soldier　by　him；　that　bade　him　go　with　him　to　Marcellus。　Notwithstanding；　he　spake　to　the　soldier；　and　bade　him　tarry　until　he　had　done　his　conclusion；　and　brought　it　to　demonstration：　but　the　soldier　being　angry　with　his　answer；　drew　out　his　sword　and　killed　him。　Others　say；　that　the　Roman　soldier　when　he　came；　offered　the　sword's　point　to　him；　to　kill　him：　and　that　Archimedes　when　he　saw　him；　prayed　him　to　hold　his　hand　a　little；　that　he　might　not　leave　the　matter　he　looked　for　imperfect；　without　demonstration。　But　the　soldier　making　no　reckoning　of　his　speculation；　killed　him　presently。　It　is　reported　a　third　way　also；　saying　that　certain　soldiers　met　him　in　the　streets　going　to　Marcellus；　carrying　certain　mathematical　instruments　in　a　little　pretty　coffer；　as　dials　for　the　sun；　spheres；　and　angles；　wherewith　they　measure　the　greatness　of　the　body　of　the　sun　by　view：　and　they　supposing　he　had　carried　some　gold　or　silver；　or　other　precious　jewels　in　that　little　coffer；　slew　him　for　it。　But　it　is　most　certain　that　Marcellus　was　marvellously　sorry　for　his　death；　and　ever　after　hated　the　villain　that　slew　him；　as　a　cursed　and　execrable　person：　and　how　he　had　made　also　marvellous　much　afterwards　of　Archimedes'　kinsmen　for　his　sake。〃　We　are　further　indebted　to　Plutarch　for　a　summary　of　the　character　and　influence　of　Archimedes；　and　for　an　interesting　suggestion　as　to　the　estimate　which　the　great　philosopher　put　upon　the　relative　importance　of　his　own　discoveries。　〃Notwithstanding　Archimedes　had　such　a　great　mind；　and　was　so　profoundly　learned；　having　hidden　in　him　the　only　treasure　and　secrets　of　geometrical　inventions：　as　be　would　never　set　forth　any　book　how　to　make　all　these　warlike　engines；　which　won　him　at　that　time　the　fame　and　glory；　not　of　man's　knowledge；　but　rather　of　divine　wisdom。　But　he　esteeming　all　kind　of　handicraft　and　invention　to　make　engines；　and　generally　all　manner　of　sciences　bringing　common　commodity　by　the　use　of　them；　to　be　but　vile；　beggarly；　and　mercenary　dross：　employed　his　wit　and　study　only　to　write　things；　the　beauty　and　subtlety　whereof　were　not　mingled　anything　at　all　with　necessity。　For　all　that　he　hath　written；　are　geometrical　propositions；　which　are　without　comparison　of　any　other　writings　whatsoever：　because　the　subject　where　of　they　treat；　doth　appear　by　demonstration；　the　maker　gives　them　the　grace　and　the　greatness；　and　the　demonstration　proving　it　so　exquisitely；　with　wonderful　reason　and　facility；　as　it　is　not　repugnable。　For　in　all　geometry　are　not　to　be　found　more　profound　and　difficult　matters　written；　in　more　plain　and　simple　terms；　and　by　more　easy　principles；　than　those　which　he　hath　invented。　Now　some　do　impute　this；　to　the　sharpness　of　his　wit　and　understanding；　which　was　a　natural　gift　in　him：　others　do　refer　it　to　the　extreme　pains　he　took；　which　made　these　things　come　so　easily　from　him；　that　they　seemed　as　if　they　had　been　no　trouble　to　him　at　all。　For　no　man　living　of　himself　can　devise　the　demonstration　of　his　propositions；　what　pains　soever　he　take　to　seek　it：　and　yet　straight　so　soon　as　he　cometh　to　declare　and　open　it；　every　man　then　imagineth　with　himself　he　could　have　found　it　out　well　enough；　he　can　then　so　plainly　make　demonstration　of　the　thing　he　meaneth　to　show。　And　therefore　that　methinks　is　likely　to　be　true；　which　they　write　of　him：　that　he　was　so　ravished　and　drunk　with　the　sweet　enticements　of　this　siren；　which　as　it　were　lay　continually　with　him；　as　he　forgot　his　meat　and　drink；　and　was　careless　otherwise　of　himself；　that　oftentimes　his　servants　got　him　against　his　will　to　the　baths　to　wash　and　anoint　him：　and　yet　being　there；　he　would　ever　be　drawing　out　of　the　geometrical　figures；　even　in　the　very　imbers　of　the　chimney。　And　while　they　were　anointing　of　him　with　oils　and　sweet　savours；　with　his　finger　he　did　draw　lines　upon　his　naked　body：　so　far　was　he　taken　fro