DuringtheirsojournonJupitertheyhadhadbutlittleexperiencewiththetremendouswindsthattheyknew,fromreasonandobservation,mustrageinitsatmosphere。Theynowheardthemwhistlingovertheirheads,and,notwithstandingtheprotectionaffordedbythesidesofthecanon,occasionallyreceivedagustthatmadetheCallistoswerve。Theykeptonsteadily,however,tillsunset,atwhichtimeitbecameverydarkonaccountofthehighbanks,whichroseassteeplyasthePalisadesontheHudsontoaheightofnearlyathousandfeet。
Findingasmallislandneartheeasternbank,theyweregladtosecuretheCallistothereforthenight,belowthereachofthewinds,whichthey,stillheardsingingloudlybutwithamusicalnoteinwhatseemedtothemlikethesky。
\"Itisincomprehensibletome。\"saidAyrault,astheysatatdinner,\"howthesun,atadistanceoffourhundredandeighty—threemillionmiles,canraisetheamountofwaterwehaveherepassingus,andcomparedwithwhichthedischargeofthegreatestriveronearthwouldbeinsignificant,tosaynothingofthestreamweascendedbeforereachingthis。\"
\"Wemustremember,\"repliedCortlandt,\"thatmanyoftheconditionsaredifferentherefromthosethatexistonearth。Weknowthatsomeofthestreamsarewarm,andevenhot,andthatthetemperatureofDeepwatersBay,anddoubtlessthatoftheoceanalso,isconsiderablyhigherthanours。Thiswouldfacilitateevaporation。Thedensityoftheatmosphereandthetremendouswinds,ofwhichIsuspectwemayseemorelater,mustalsohelpthesunverymuchinitsworkofraisingvapour。Butthemostpotentfactorisundoubtedlythevastsizeofthebasinthattheseriversdrain。\"
\"Thegreatspeedatwhichtheatmosphericcurrentsmove,\"saidBearwarden,\"coupledwiththecomparativelownessofthemountainchainsandtheslightobstructiontheyoffertotheirpassage,mustdistributetherainverythoroughly,notwithstandingthegreatunbrokenareaofthecontinents。TherecanbenosuchstateofthingshereasexistsinthewesternpartofSouthAmerica,wheretheAndesaresohighthatanyeast—boundclouds,incrossingthem,areshovedupsofarintoacoldregionthatallmoisturetheymayhavebroughtfromthePacificiscondensedintorain,withwhichpartsofthewesternslopearedeluged,whilecloudsfromtheAtlantichavecomesofartheyhavealreadydispersedtheirmoisture,inconsequenceofwhichtheregionjusteastoftheAndesgetslittleifanyrain。Itisbadforacontinenttohaveitshighmountainsneartheoceanfromwhichitshouldgetitsrain,andgoodforittohavethemsetwellback。\"