Therailroadsofthenearfuturewillprobablynotinvolveanyspectacularlynewprinciplebutwillbedevelopmentsofthoseweusetoday.Therailadministrationshavebuilttheirentiresystemtoastereotypedmodel,withtwosteelrailsofaparticulartypeseparatedbya“gauge”ofabout1.43m,1.07m...[继续阅读]

    Aharborisanyplacethatprovidesseagoingshipsorboatsofanykindwithameasureofprotectionfromthewindandwaves.Tofulfillthisrole,aharbormustbedeepenoughtoaccommodatethelargestshipsthatmayuseit,andhaveabottomthatwillholdthematanchor.Aportisaharborwithfacilitiesfort...[继续阅读]

    ModerncanalprovideimportanttransporthighwaysthroughoutEuropeand,toalesserextent,NorthAmerica.TheriversRhineandMosellefeedandxtensivecanalsysteminGermanythathasconnectionstotheDutch,Belgian,andFrenchnetworks.AnewmajorwaterwayiscompletedtoconnecttheRhinewit...[继续阅读]

    Controlofhislife-sustainingwatersupplyhasalwaysbeenoneofman’sprimaryconcerns.For5,000years,damshavebeeninstrumentalinthiscontrol,beingusedtoavertfloods,divertrivers,storewater,andirrigateland.Manyoftoday’sconstructionsfulfillthesesameage-oldfunctions;dams...[继续阅读]

    Themoreprosperousmanbecomes,themorewaterheuses.In1980sindevelopingcountries(theThirdWorld),somecommunitiesmanagewithanaverageof2.5gallons(12liters)ofwaterperpersonperday.InmostEuropeancitiesthedailydomesticconsumptionpercapitaofthepopulationisnearer33gall...[继续阅读]

    Assoonasearlypeoplesestablishedsettlementtheyhadtheproblemofgettingridofsewage——theirorganicwastesand,sometimes,thoseofdomesticanimals.Naturedisposesofsurplusorganicmaterialinfourprincipalwaysbydilution,oxidation,putrefaction,andfiltration.Earlypeoplesrel...[继续阅读]