选修九 Unit 2 Reading

ZhengHeMarcoPoloJamesCookHowdoyouthinkseamenfoundtheirwaybeforemodernaccuratemethodsofnavigationwereinvented?Howdidtheynavigatesowell?compassastrolabe(星盘)sextant(六分仪)sea/nauticalchartearlynavigationalinstrumentsaquadrant(四分仪)aspecialtoolfortellingthepositionoftheshipinrelationtothesunandvariousstarsanastrolabemeasurehowhighstarswereabovethehorizonanupdatednavigationalinstrumenttomeasuretheanglebetweentwofixedpointsoutsidetheshipsextantabearingcircle方位圆thefirstinstrumenttomeasurethesun’spositionandthesun’sshadowAlatitudeanautical/seachartlongitudeReadaboutwhatnavigationwaslikebeforemoderninstrumentswereused.(25minutes)SailingtheoceansFast-readingtogetthegeneralidea.(10minutes)Page1UsingnatureKeepingalongsidethecoastlineUsingcelestialbodiesUsingwildlifeUsingtheweatherUsingthesea(1minute)Usingcelestialbodiestoplotthepositionstoworkoutthelatitudeaspecialcloudformationindicatesthereislandcloseby(2minutes)________________________________________________________________________UsingwildlifeIfseaweedwasfreshandsmelledstrongly,theship____________land.Seabirdscouldbeusedto__________________whenitwasnowheretobeseen.(1minute)wasclosetoshowthewaytolandUsingtheweatherTo______________________ofastreamorriverwhen…theirsailing(1minute)helpidentifytheposition_________________________TodirectUsetheinformationtoanalyzethenavigationalskillsandwritetheanswersinyourownwords.1.Tofindtheship’spositionatseaasailorused_______________________.2.Asailorknewthatlandwasnearbyifhesaw_________________________________________________________.3.Sailorsused______________________________toincreasetheirspeed.theNorthStarandthesunseacurrentsortidesandwindsUsingnaturefreshseaweed,nestingbirdsreturninghomeintheeveningorfog(5minutes)Fast-readingtogetthegeneralidea.thenanswerthequestions.Page2(10minutes)Usingnavigationalinstruments1.Findinglongitude2.Findinglatitudethecompassthebearingcircle(方位圆)theastrolabe(星盘)thequadrant(象限仪,四分仪)thesextant(六分仪)(2minutes)1.Readthepassageandanswerthefollowingquestions.1.Whatistheuseofabearingcircle,astrolabe,quadrantorsextant?()Whatistheuseofacompass?()A.tosetthecourseoftheshipB.tomeasurethepositionoftheshipC.tomeasurethespeedoftheshipD.totellthetimeBAUsinginstruments(2minutes)2.ReadagainandfillintheblanksThereweretwomethodstofindlongitude:1.___________________________2.______________________________________________________measuringtimeandspeedcompassandcomplicatedmathematicaltablesUsinginstruments(1minute)horizonSunheightABearingCircleThemarkswereusedto____________________ofthesunanditsheightandpositioninthesky.(方位)3.Writedowntheworkingprinciplesofthefollowinginstruments:measuretheshadowa__________________oftheastrolabe,tomeasurehowhighstarsare___________________,andcomparethatmeasurementwithpreviousmeasurements.Quadrant:(四分仪)morepreciseversionhorizonabovetheAstrolabe:(星盘)tocomparethepositionoftheshipinrelationto_____________________somestarsorthesun.an_________________ofthequadrantandsoitwasmoreaccurate,to__________________betweentwofixedobjectsoutsidetheship.Sextant:(六分仪)updatedversiontheanglemeasure1.ListentothetapeandthenanswerthequestionsDetailedreadingPage2(5minutes)(1).Whyarespeedandtimeimportantinworkingoutthelongitudeofaship?Becausetheearthmovesfifteendegreeswestwardseveryhour.Ifyouknowyourdirection,speedandtime,youcanworkouttheapproximatelongitudeorchangeinyourpositioninrelationtothestars.(2).Whyisthepositionofthesunandvariousstarsusefulforworkingoutlatitude?Becausetheyarefixedpointsintheskyandtheirmovementsinrelationtotheeartharealreadyknown.Sotheycanbeusedtomeasureaship’sposition.Readthepassageanddecidewhetherthefollowingstatementsaretrue(T)orfalse(F).1.Anearlymethodofcalculatinglongitudewastouseaknottedropetiedtoalog.2.Theastrolabewasthefirstinstrumenttomeasurethesun’sposition.3.Thequadrantwasmorepreciseandsimplifiedthantheastrolabe,butstillhaditsshortcoming.TFT4.Uptillnow,themostaccurateandreliablenavigationalinstrumentisthesextant.5.Theastrolabe,quadrantandsextantaredifferentkindsofnavigationalinstrumentsandtheyhavenothingtodowitheachother.FF