meteorology-第12章

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blows　from　D；　coming　from　the　point　where　the　sun　rises　at　the



winter　solstice。　It　borders　on　Notus；　and　so　we　often　find　that　people



speak　of　'Euro…Noti'。　Its　contrary　is　not　Lips　blowing　from　G　but



the　wind　that　blows　from　E　which　some　call　Argestes；　some　Olympias；



and　some　Sciron。　This　blows　from　the　point　where　the　sun　sets　at　the



summer　solstice；　and　is　the　only　wind　that　is　diametrically　opposite



to　Eurus。　These　are　the　winds　that　are　diametrically　opposite　to　one



another　and　their　contraries。



　　There　are　other　winds　which　have　no　contraries。　The　wind　they　call



Thrascias；　which　lies　between　Argestes　and　Aparctias；　blows　from　I；



and　the　wind　called　Meses；　which　lies　between　Caecias　and　Aparctias；



from　K。　（The　line　IK　nearly　coincides　with　the　ever　visible　circle；



but　not　quite。）　These　winds　have　no　contraries。　Meses　has　not；　or　else



there　would　be　a　wind　blowing　from　the　point　M　which　is



diametrically　opposite。　Thrascias　corresponding　to　the　point　I　has



not；　for　then　there　would　be　a　wind　blowing　from　N；　the　point　which　is



diametrically　opposite。　（But　perhaps　a　local　wind　which　the



inhabitants　of　those　parts　call　Phoenicias　blows　from　that　point。）



　　These　are　the　most　important　and　definite　winds　and　these　their



places。



　　There　are　more　winds　from　the　north　than　from　the　south。　The



reason　for　this　is　that　the　region　in　which　we　live　lies　nearer　to　the



north。　Also；　much　more　water　and　snow　is　pushed　aside　into　this



quarter　because　the　other　lies　under　the　sun　and　its　course。　When　this



thaws　and　soaks　into　the　earth　and　is　exposed　to　the　heat　of　the　sun



and　the　earth　it　necessarily　causes　evaporation　to　rise　in　greater



quantities　and　over　a　greater　space。



　　Of　the　winds　we　have　described　Aparctias　is　the　north　wind　in　the



strict　sense。　Thrascias　and　Meses　are　north　winds　too。　（Caecias　is



half　north　and　half　east。）　South　are　that　which　blows　from　due　south



and　Lips。　East；　the　wind　from　the　rising　of　the　sun　at　the　equinox　and



Eurus。　Phoenicias　is　half　south　and　half　east。　West；　the　wind　from　the



true　west　and　that　called　Argestes。　More　generally　these　winds　are



classified　as　northerly　or　southerly。　The　west　winds　are　counted　as



northerly；　for　they　blow　from　the　place　of　sunset　and　are　therefore



colder；　the　east　winds　as　southerly；　for　they　are　warmer　because



they　blow　from　the　place　of　sunrise。　So　the　distinction　of　cold　and



hot　or　warm　is　the　basis　for　the　division　of　the　winds　into



northerly　and　southerly。　East　winds　are　warmer　than　west　winds　because



the　sun　shines　on　the　east　longer；　whereas　it　leaves　the　west　sooner



and　reaches　it　later。



　　Since　this　is　the　distribution　of　the　winds　it　is　clear　that



contrary　winds　cannot　blow　simultaneously。　They　are　diametrically



opposite　to　one　another　and　one　of　the　two　must　be　overpowered　and



cease。　Winds　that　are　not　diametrically　opposite　to　one　another　may



blow　simultaneously：　for　instance　the　winds　from　Z　and　from　D。　Hence



it　sometimes　happens　that　both　of　them；　though　different　winds　and



blowing　from　different　quarters；　are　favourable　to　sailors　making



for　the　same　point。



　　Contrary　winds　commonly　blow　at　opposite　seasons。　Thus　Caecias　and



in　general　the　winds　north　of　the　summer　solstice　blow　about　the



time　of　the　spring　equinox；　but　about　the　autumn　equinox　Lips；　and



Zephyrus　about　the　summer　solstice；　but　about　the　winter　solstice



Eurus。



　　Aparctias；　Thrascias；　and　Argestes　are　the　winds　that　fall　on　others



most　and　stop　them。　Their　source　is　so　close　to　us　that　they　are



greater　and　stronger　than　other　winds。　They　bring　fair　weather　most　of



all　winds　for　the　same　reason；　for；　blowing　as　they　do；　from　close



at　hand；　they　overpower　the　other　winds　and　stop　them；　they　also



blow　away　the　clouds　that　are　forming　and　leave　a　clear　sky…unless



they　happen　to　be　very　cold。　Then　they　do　not　bring　fair　weather；



but　being　colder　than　they　are　strong　they　condense　the　clouds



before　driving　them　away。



　　Caecias　does　not　bring　fair　weather　because　it　returns　upon



itself。　Hence　the　saying：　'Bringing　it　on　himself　as　Caecias　does



clouds。'



　　When　they　cease；　winds　are　succeeded　by　their　neighbours　in　the



direction　of　the　movement　of　the　sun。　For　an　effect　is　most　apt　to



be　produced　in　the　neighbourhood　of　its　cause；　and　the　cause　of



winds　moves　with　the　sun。



　　Contrary　winds　have　either　the　same　or　contrary　effects。　Thus　Lips



and　Caecias；　sometimes　called　Hellespontias；　are　both　rainy　gestes　and



Eurus　are　dry：　the　latter　being　dry　at　first　and　rainy　afterwards。



Meses　and　Aparctias　are　coldest　and　bring　most　snow。　Aparctias；



Thrascias；　and　Argestes　bring　hail。　Notus；　Zephyrus；　and　Eurus　are



hot。　Caecias　covers　the　sky　with　heavy　clouds；　Lips　with　lighter　ones。



Caecias　does　this　because　it　returns　upon　itself　and　combines　the



qualities　of　Boreas　and　Eurus。　By　being　cold　it　condenses　and



gathers　the　vaporous　air；　and　because　it　is　easterly　it　carries　with



it　and　drives　before　it　a　great　quantity　of　such　matter。　Aparctias；



Thrascias；　and　Argestes　bring　fair　weather　for　the　reason　we　have



explained　before。　These　winds　and　Meses　are　most　commonly



accompanied　by　lightning。　They　are　cold　because　they　blow　from　the



north；　and　lightning　is　due　to　cold；　being　ejected　when　the　clouds



contract。　Some　of　these　same　bring　hail　with　them　for　the　same　reason；



namely；　that　they　cause　a　sudden　condensation。



　　　　Hurricanes　are　commonest　in　autumn；　and　next　in　spring：　Aparctias；



Thrascias；　and　Argestes　give　rise　to　them　most。　This　is　because



hurricanes　are　generally　formed　when　some　winds　are　blowing　and　others



fall　on　them；　and　these　are　the　winds　which　are　most　apt　to　fall　on



others　that　are　blowing；　the　reason　for　which；　too；　we　have



explained　before。



　　The　Etesiae　veer　round：　they　begin　from　the　north；　and　become　for



dwellers　in　the　west　Thrasciae；　Argestae；　and　Zephyrus　（for　Zephyrus



belongs　to　the　north）。　For　dwellers　in　the　east　they　veer　round　as　far



as　Apeliotes。



　　So　much　for　the　winds；　their　origin　and　nature　and　the　properties



common　to　them　all　or　peculiar　to　each。







　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　7







　　We　must　go　on　to　discuss　earthquakes　next；　for　their　cause　is　akin



to　our　last　subject。



　　The　theories　that　have　been　put　forward　up　to　the　present　date　are



three；　and　their　authors　three　men；　Anaxagoras　of　Clazomenae；　and



before　him　Anaximenes　of　Miletus；　and　later　Democritus　of　Abdera。



　　Anaxagoras　says　that　the　ether；　which　naturally　moves　upwards；　is



caught　in　hollows　below　the　earth　and　so　shakes　it；　for　though　the



earth　is　really　all　of　it　equally　porous；　its　surface　is　clogged　up　by



rain。　This　implies　that　part　of　the　whole　sphere　is　'above'　and　part



'below'：　'above'　being　the　part　on　which　we　live；　'below'　the　other。



　　This　theory　is　perhaps　too　primitive　to　require　refutation。　It　is



absurd　to　think　of　up　and　down　otherwise　than　as　meaning　that　heavy



bodies　move　to　the　earth　from　every　quarter；　and　light　ones；　such　as



fire；　away　from　it；　especially　as　we　see　that；　as　far　as　our　knowledge



of　the　earth　goes；　the　horizon　always　changes　with　a　change　in　our



position；　which　proves　that　the　earth　is　convex　and　spherical。　It　is



absurd；　too；　to　maintain　that　the　earth　rests　on　the　air　because　of



its　size；　and　then　to　say　that　impact　upwards　from　below　shakes　it



right　through。　Besides　he　gives　no　account　of　the　circumstances



attendant　on　earthquakes：　for　not　every　country　or　every　season　is



subject　to　them。



　　Democritus　says　that　the　earth　is　full　of　water　and　that　when　a



quantity　of　rain…water　is　added　to　this　an　earthquake　is　the　result。



The　hollows　in　the　earth　being　unable　to　admit　the　excess　of　water



it　forces　its　way　in　and　so　causes　an　earthquake。　Or　again；　the



earth　as　it　dries　draws　the　water　from　the　fuller　to　the　emptier



parts；　and　the　inrush　of　the　water　as　it　changes　its　place　causes



the　earthquake。



　　Anaximenes　says　that　the　earth　breaks　up　when　it　grows　wet　or　dry；



and　earthquakes　are　due　to　the　fall　of　these　masses　as　they　break



away。　Hence　earthquakes　take　place　in　times　of　drought　and　again　of



heavy　rain；　since；　as　we　have　explained；　the　earth　grows　dry　in　time



of　drought　and　breaks　up；　whereas　the　rain　makes　it　sodden　and



destroys　its　cohesion。



　　But　if　this　were　the　case　the　earth　ought　to　be　found　to　be



sinking　in　many　places。　Again；　why　do　earthquakes　frequently　occur



in　places　which　are　not　excessively　subject　to　drought　or　rain；　as



they　ought　to　be　on　the　theory？　Besides；　on　this　view；　earthquakes



ought　always　to　be　getting　fewer；　and　should　come　to　an　end　entirely



some　day：　the　notion　of　contraction　by　packing　together　implies



this。　So　this　is　impossible　the　theory　must　be　impossible　too。







　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　8







　　　　We　have　already　shown　that　wet　and　dry　must　both　give　rise　to　an



evaporation：　earthquakes　are　a　necessary　consequence　of　this　fact。　The



earth　is　essentially　dry；　but　rain　fills　it　with　moisture。　Then　the



sun　and　its　own　fire　warm　it　and　give　rise　to　a　quantity　of　wind



both　outside　and　inside　it。　This　wind　sometimes　flows　outwards　in　a



single　body；　sometimes　inwards；　and　sometimes　it　is　divided。　All　these



are　necessary　laws。　Next　we　must　find　out　what　body　has　the　greatest



motive　force。　This　will　certainly　be　the　body　that　naturally　moves



farthest　and　is　most　violent。　Now　that　which　has　the　most　rapid　motion



is　necessarily　the　most　violent；　for　its　swiftness　gives　its　impact



the　greatest　force。　Again；　the　rarest　body；　that　which　can　most



readily　pass　through　every　other　body；　is　that　which　naturally　moves



farthest。　Wind　satisfies　these　conditions　in　the　highest　degree



（fire　only　becomes　flame　and　moves　rapidly　when　wind　accompanies



it）：　so　that　not　water　nor　earth　is　the　cause　of　earthquakes　but



wind…that　is；　the　inrush　of　the　external　evaporation　into　the　earth。



　　Hence；　since　the　evaporation　generally　follows　in　a　continuous



body　in　the　direction　in　which　it　first　started；　and　either　all　of



it　flows　inwards　or　all　outwards；　most　earthquakes　and　the　greatest



are　accompanied　by　calm。　It　is　true　that　some　take　place　when　a　wind



is　blowing；　but　this　presents　no　difficulty。　We　sometimes　find　several



winds　blowing　simultaneously。　If　one　of　these　enters　the　earth　we



get　an　earthquake　attended　by　wind。　Only　these　earthquakes　are　less



severe　because　their　source　and　cause　is　divided。



　　Again；　most　earthquakes　and　the　severest　occur　at　night　or；　if　by



day；　about　noon；　that　being　generally　the　calmest　part　of　the　day。　For



when　the　sun　exerts　its　full　power　（as　it　does　about　noon）　it　shuts



the　evaporation　into　the　earth。　Night；　too；　is　ca