meteorology-第1章

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　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　METEOROLOGY





　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　by　Aristotle





　　　　　　　　　　　　　　　　　　　　　　　　　　translated　by　E。　W。　Webster











　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　Book　I







　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　1







　　WE　have　already　discussed　the　first　causes　of　nature；　and　all



natural　motion；　also　the　stars　ordered　in　the　motion　of　the　heavens；



and　the　physical　element…enumerating　and　specifying　them　and　showing



how　they　change　into　one　another…and　becoming　and　perishing　in



general。　There　remains　for　consideration　a　part　of　this　inquiry



which　all　our　predecessors　called　meteorology。　It　is　concerned　with



events　that　are　natural；　though　their　order　is　less　perfect　than



that　of　the　first　of　the　elements　of　bodies。　They　take　place　in　the



region　nearest　to　the　motion　of　the　stars。　Such　are　the　milky　way；　and



comets；　and　the　movements　of　meteors。　It　studies　also　all　the



affections　we　may　call　common　to　air　and　water；　and　the　kinds　and



parts　of　the　earth　and　the　affections　of　its　parts。　These　throw



light　on　the　causes　of　winds　and　earthquakes　and　all　the



consequences　the　motions　of　these　kinds　and　parts　involve。　Of　these



things　some　puzzle　us；　while　others　admit　of　explanation　in　some



degree。　Further；　the　inquiry　is　concerned　with　the　falling　of



thunderbolts　and　with　whirlwinds　and　fire…winds；　and　further；　the



recurrent　affections　produced　in　these　same　bodies　by　concretion。　When



the　inquiry　into　these　matters　is　concluded　let　us　consider　what



account　we　can　give；　in　accordance　with　the　method　we　have　followed；



of　animals　and　plants；　both　generally　and　in　detail。　When　that　has



been　done　we　may　say　that　the　whole　of　our　original　undertaking　will



have　been　carried　out。



　　After　this　introduction　let　us　begin　by　discussing　our　immediate



subject。







　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　2







　　We　have　already　laid　down　that　there　is　one　physical　element　which



makes　up　the　system　of　the　bodies　that　move　in　a　circle；　and　besides



this　four　bodies　owing　their　existence　to　the　four　principles；　the



motion　of　these　latter　bodies　being　of　two　kinds：　either　from　the



centre　or　to　the　centre。　These　four　bodies　are　fire；　air；　water；



earth。　Fire　occupies　the　highest　place　among　them　all；　earth　the



lowest；　and　two　elements　correspond　to　these　in　their　relation　to



one　another；　air　being　nearest　to　fire；　water　to　earth。　The　whole



world　surrounding　the　earth；　then；　the　affections　of　which　are　our



subject；　is　made　up　of　these　bodies。　This　world　necessarily　has　a



certain　continuity　with　the　upper　motions：　consequently　all　its



power　and　order　is　derived　from　them。　（For　the　originating　principle



of　all　motion　is　the　first　cause。　Besides；　that　clement　is　eternal　and



its　motion　has　no　limit　in　space；　but　is　always　complete；　whereas



all　these　other　bodies　have　separate　regions　which　limit　one　another。）



So　we　must　treat　fire　and　earth　and　the　elements　like　them　as　the



material　causes　of　the　events　in　this　world　（meaning　by　material



what　is　subject　and　is　affected）；　but　must　assign　causality　in　the



sense　of　the　originating　principle　of　motion　to　the　influence　of　the



eternally　moving　bodies。







　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　3







　　Let　us　first　recall　our　original　principles　and　the　distinctions



already　drawn　and　then　explain　the　'milky　way'　and　comets　and　the



other　phenomena　akin　to　these。



　　Fire；　air；　water；　earth；　we　assert；　originate　from　one　another；



and　each　of　them　exists　potentially　in　each；　as　all　things　do　that　can



be　resolved　into　a　common　and　ultimate　substrate。



　　The　first　difficulty　is　raised　by　what　is　called　the　air。　What　are



we　to　take　its　nature　to　be　in　the　world　surrounding　the　earth？　And



what　is　its　position　relatively　to　the　other　physical　elements。　（For



there　is　no　question　as　to　the　relation　of　the　bulk　of　the　earth　to



the　size　of　the　bodies　which　exist　around　it；　since　astronomical



demonstrations　have　by　this　time　proved　to　us　that　it　is　actually



far　smaller　than　some　individual　stars。　As　for　the　water；　it　is　not



observed　to　exist　collectively　and　separately；　nor　can　it　do　so



apart　from　that　volume　of　it　which　has　its　seat　about　the　earth：　the



sea；　that　is；　and　rivers；　which　we　can　see；　and　any　subterranean　water



that　may　be　hidden　from　our　observation。）　The　question　is　really　about



that　which　lies　between　the　earth　and　the　nearest　stars。　Are　we　to



consider　it　to　be　one　kind　of　body　or　more　than　one？　And　if　more



than　one；　how　many　are　there　and　what　are　the　bounds　of　their　regions？



　　We　have　already　described　and　characterized　the　first　element；　and



explained　that　the　whole　world　of　the　upper　motions　is　full　of　that



body。



　　This　is　an　opinion　we　are　not　alone　in　holding：　it　appears　to　be



an　old　assumption　and　one　which　men　have　held　in　the　past；　for　the



word　ether　has　long　been　used　to　denote　that　element。　Anaxagoras；　it



is　true；　seems　to　me　to　think　that　the　word　means　the　same　as　fire。



For　he　thought　that　the　upper　regions　were　full　of　fire；　and　that



men　referred　to　those　regions　when　they　spoke　of　ether。　In　the



latter　point　he　was　right；　for　men　seem　to　have　assumed　that　a　body



that　was　eternally　in　motion　was　also　divine　in　nature；　and；　as　such　a



body　was　different　from　any　of　the　terrestrial　elements；　they



determined　to　call　it　'ether'。



　　For　the　um　opinions　appear　in　cycles　among　men　not　once　nor　twice；



but　infinitely　often。



　　Now　there　are　some　who　maintain　that　not　only　the　bodies　in　motion



but　that　which　contains　them　is　pure　fire；　and　the　interval　between



the　earth　and　the　stars　air：　but　if　they　had　considered　what　is　now



satisfactorily　established　by　mathematics；　they　might　have　given　up



this　puerile　opinion。　For　it　is　altogether　childish　to　suppose　that



the　moving　bodies　are　all　of　them　of　a　small　size；　because　they　so



to　us；　looking　at　them　from　the　earth。



　　This　a　matter　which　we　have　already　discussed　in　our　treatment　of



the　upper　region；　but　we　may　return　to　the　point　now。



　　If　the　intervals　were　full　of　fire　and　the　bodies　consisted　of



fire　every　one　of　the　other　elements　would　long　ago　have　vanished。



　　However；　they　cannot　simply　be　said　to　be　full　of　air　either；　for



even　if　there　were　two　elements　to　fill　the　space　between　the　earth



and　the　heavens；　the　air　would　far　exceed　the　quantitu　required　to



maintain　its　proper　proportion　to　the　other　elements。　For　the　bulk



of　the　earth　（which　includes　the　whole　volume　of　water）　is



infinitesimal　in　comparison　with　the　whole　world　that　surrounds　it。



Now　we　find　that　the　excess　in　volume　is　not　proportionately　great



where　water　dissolves　into　air　or　air　into　fire。　Whereas　the



proportion　between　any　given　small　quantity　of　water　and　the　air



that　is　generated　from　it　ought　to　hold　good　between　the　total



amount　of　air　and　the　total　amount　of　water。　Nor　does　it　make　any



difference　if　any　one　denies　that　the　elements　originate　from　one



another；　but　asserts　that　they　are　equal　in　power。　For　on　this　view　it



is　certain　amounts　of　each　that　are　equal　in　power；　just　as　would　be



the　case　if　they　actually　originated　from　one　another。



　　So　it　is　clear　that　neither　air　nor　fire　alone　fills　the



intermediate　space。



　　It　remains　to　explain；　after　a　preliminary　discussion　of



difficulties；　the　relation　of　the　two　elements　air　and　fire　to　the



position　of　the　first　element；　and　the　reason　why　the　stars　in　the



upper　region　impart　heat　to　the　earth　and　its　neighbourhood。　Let　us



first　treat　of　the　air；　as　we　proposed；　and　then　go　on　to　these



questions。



　　Since　water　is　generated　from　air；　and　air　from　water；　why　are



clouds　not　formed　in　the　upper　air？　They　ought　to　form　there　the　more；



the　further　from　the　earth　and　the　colder　that　region　is。　For　it　is



neither　appreciably　near　to　the　heat　of　the　stars；　nor　to　the　rays



relected　from　the　earth。　It　is　these　that　dissolve　any　formation　by



their　heat　and　so　prevent　clouds　from　forming　near　the　earth。　For



clouds　gather　at　the　point　where　the　reflected　rays　disperse　in　the



infinity　of　space　and　are　lost。　To　explain　this　we　must　suppose　either



that　it　is　not　all　air　which　water　is　generated；　or；　if　it　is　produced



from　all　air　alike；　that　what　immediately　surrounds　the　earth　is　not



mere　air；　but　a　sort　of　vapour；　and　that　its　vaporous　nature　is　the



reason　why　it　condenses　back　to　water　again。　But　if　the　whole　of



that　vast　region　is　vapour；　the　amount　of　air　and　of　water　will　be



disproportionately　great。　For　the　spaces　left　by　the　heavenly　bodies



must　be　filled　by　some　element。　This　cannot　be　fire；　for　then　all



the　rest　would　have　been　dried　up。　Consequently；　what　fills　it　must　be



air　and　the　water　that　surrounds　the　whole　earth…vapour　being　water



dissolved。



　　After　this　exposition　of　the　difficulties　involved；　let　us　go　on



to　lay　down　the　truth；　with　a　view　at　once　to　what　follows　and　to　what



has　already　been　said。　The　upper　region　as　far　as　the　moon　we　affirm



to　consist　of　a　body　distinct　both　from　fire　and　from　air；　but　varying



degree　of　purity　and　in　kind；　especially　towards　its　limit　on　the　side



of　the　air；　and　of　the　world　surrounding　the　earth。　Now　the　circular



motion　of　the　first　element　and　of　the　bodies　it　contains　dissolves；



and　inflames　by　its　motion；　whatever　part　of　the　lower　world　is



nearest　to　it；　and　so　generates　heat。　From　another　point　of　view　we



may　look　at　the　motion　as　follows。　The　body　that　lies　below　the



circular　motion　of　the　heavens　is；　in　a　sort；　matter；　and　is



potentially　hot；　cold；　dry；　moist；　and　possessed　of　whatever　other



qualities　are　derived　from　these。　But　it　actually　acquires　or



retains　one　of　these　in　virtue　of　motion　or　rest；　the　cause　and



principle　of　which　has　already　been　explained。　So　at　the　centre　and



round　it　we　get　earth　and　water；　the　heaviest　and　coldest　elements；　by



themselves；　round　them　and　contiguous　with　them；　air　and　what　we



commonly　call　fire。　It　is　not　really　fire；　for　fire　is　an　excess　of



heat　and　a　sort　of　ebullition；　but　in　reality；　of　what　we　call　air；



the　part　surrounding　the　earth　is　moist　and　warm；　because　it



contains　both　vapour　and　a　dry　exhalation　from　the　earth。　But　the　next



part；　above　that；　is　warm　and　dry。　For　vapour　is　naturally　moist　and



cold；　but　the　exhalation　warm　and　dry；　and　vapour　is　potentially



like　water；　the　exhalation　potentially　like　fire。　So　we　must　take



the　reason　why　clouds　are　not　formed　in　the　upper　region　to　be　this：



that　it　is　filled　not　with　mere　air　but　rather　with　a　sort　of　fire。



　　However；　it　may　well　be　that　the　formation　of　clouds　in　that　upper



region　is　also　prevented　by　the　circular　motion。　For　the　air　round　the



earth