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高中英语现代文背诵篇章30TheoriginofRefrigerators素材.doc

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30TheoriginofRefrigeratorsBythemid-nineteenthcentury,theterm“icebox”hadenteredtheAmericanlanguage,buticewasstillonlybeginningtoaffectthedietofordinarycitizensintheUnitedStates.Theicetradegrewwiththegrowthofcities.Icewasusedinhotels,taverns,andhospitals,andbysomeforward-lookingcitydealersinfreshmeat,freshfish,andbutter.AftertheCivilWar(1861-1865),asicewasusedtorefrigeratefreightcars,italsocameintohouseholduse.Evenbefore1880,halfoftheicesoldinNewYork,Philadelphia,andBaltimore,andone-thirdofthatsoldinBostonandChicago,wenttofamiliesfortheirownuse.Thishadbecomepossiblebecauseanewhouseholdconvenience,theicebox,aprecursorofthemodernrefrigerator,hadbeeninvented.Makinganefficienticeboxwasnotaseasyaswemightnowsuppose.Intheearlynineteenthcentury,theknowledgeofthephysicsofheat,whichwasessentialtoascienceofrefrigeration,wasrudimentary.Thecommonsensenotionthatthebesticeboxwasonethatpreventedtheicefrommeltingwasofcoursemistaken,foritwasthemeltingoftheicethatperformedthecooling.Nevertheless,earlyeffortstoeconomizeiceincludedwrappinguptheiceinblankets,whichkepttheicefromdoingitsjob.Notuntilneartheendofthenineteenthcenturydidinventorsachievethedelicatebalanceofinsulationandcirculationneededforanefficienticebox.Butasearlyas1803,andingeniousMarylandfarmer,ThomasMoore,hadbeenontherighttrack.HeownedafarmabouttwentymilesoutsidethecityofWashington,forwhichthevillageofGeorgetownwasthemarketcenter.Whenheusedaniceboxofhisowndesigntotransporthisbuttertomarket,hefoundthatcustomerswouldpassuptherapidlymeltingstuffinthetubsofhiscompetitorstopayapremiumpriceforhisbutter,stillfreshandhardinneat,one-poundbricks.Oneadvantageofhisicebox,Mooreexplained,wasthatfarmerswouldnolongerhavetotraveltomarketatnightinordertokeeptheirproducecool.