2021年英语四级作文预测：冰箱的起源思维导图

TheOriginoftheRefrigerators

Bythemid-nineteenthcentury,thetermiceboxhadenteredtheAmericanlanguage,buticewasstillonlybeginningtoaffectthedietofordinarycitizensintheUnitedStates.Theicetradegrewwiththegrowthofcities.Icewasusedinhotels,taverns,andhospitals,andbysomeforward-lookingcitydealersinfreshmeat,freshfish,andbutter.

AftertheCivilWar(1861-1865),asicewasusedtorefrigeratefreightcars,italsocameintohouseholduse.Evenbefore1880halfoftheicesoldinNewYork,Philadelphia,andBaltimore,andone-thirdofthatsoldinBostonandChicago,wenttofamiliesfortheirownuse.

Thishadbecomepossiblebecauseanewhouseholdconvenience,theicebox,aprecursorofthemodernrefrigerator,hadbeeninvented.Makinganefficienticeboxwasnotaseasyaswemightnowsuppose.Intheearlynineteenthcentury,theknowledgeofthephysicsofheat,whichwasessentialtoascienceofrefrigeration,wasrudimentary.Thecommonsensenotionthatthebesticeboxwasonethatpreventedtheicefrommeltingwasofcoursemistaken,foritwasthemeltingoftheicethatperformedthecooling.

Nevertheless,earlyeffortstoeconomizeiceincludedwrappinguptheiceinblankets,whichkepttheicefromdoingitsjob.Notuntilneartheendofthenineteenthcenturydidinventorsachievethedelicatebalanceofinsulationandcirculationneededforanefficienticebox.Butasearlyas1803,aningeniousMarylandfarmer,ThomasMoore,hadbeenontherighttrack.Whenheusedaniceboxofhisowndesigntotransporthisbuttertomarket,hisbutter,stillfreshandhardinneat,wasworthone-poundabrick.Oneadvantageofhisicebox,Mooreexplained,wasthatfarmerswouldnolongerhavetotraveltomarketatnightinordertokeeptheirproducecool.