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1、Chapter30HistoryofDivingU.S.NAVYTheoriginsofdivingarefirmlyrootedintheneedsanddesiresofmentoconductmili-taryorsalvageoperations,toengageinunderwatercommerce,andtoexpandthefron-tiersofknowledgethroughexplorationandresearch.Nooneknowswhenmanfirstdiscoveredthathecouldholdhisbreathandgounder
2、water,butthebeginningsofdivingasaprofessioncanbetracedbackmorethan5000years.Theseearlydivingeffortswereconfinedtorelativelyshallowwaters(lessthan100ft),withthediversharvestingavarietyofmaterialsofcommercialvalueincludingfood,sponges,coral,andmother-of-pearl.Oneofthefirstrecordsofsuchdivi
3、ngisfoundinthewritirtgsoftheGreekhisto-rianHerodotus.HetellsthestoryofadivernamedScyllis,whowasemployedbythePersianKingXerxestorecoversunkentreasureinthefifthcenturyB.c.Fromtheearliesttimes,diverswereactiveinmilitaryoperations;andtheirmis-sionsincludedcuttinganchorcablestosetenemyshipsad
4、rift,boringorpunchingholesinthebottomsofships,andthebuildingofharbordefensesathomewhileattemptingtodestroythoseoftheenemyabroad.HistoricalrecordsindicatethatAlexandcrtheGreatnotonlysentdiversdowntoremoveobstaclesintheharborofthecityofTyre,inwhatisnowLebanon,whichhehadtakenundersiegein332
5、B-c.,butalsowentunderwaterhimselftoviewtheprogressoftheirwork.OtherearlydiversdevelopedanactivesalvageindustrycenteredaroundthemajorshippingportsoftheeasternMediterranean,BythefirScennrry8.c.,operationsinoneareahadbecomesowellorganizedthatascaleofpaymentforsalvageworkwasestablishedbylawa
6、cknowledgingthefactthateffortandriskincrcasedwithdepth.InSource:FromtheUSNavyDivingManual,Chapterl.SanPedro,CA:BescPublishingCompany,19E5.Re-printedbypermission.343.E344U.S.NaryDivinglvlanud24ftofwater,thedivencouldclaimaone-halfshareofallgoodsrecovered.In12ftofwatertheywereallowedaone-t
7、hirdshare;andin3ft,onlyaone-tenthshare.EARLYDEVELOPTVIENTSThemostobviousandnecessarystepinbroadeningthecapabilitiesofadiverwastoprovideanairsryplythatwouldpermithimtostayunderwater.Thefirstsucheffortsusedhollowroedsqobesextendingtothesurface.Theusercouldremainsubmergedfor
