高中英语 阅读课件2 新人教版选修9.ppt

reading thefourbasicinstrumentsfornavigation sinan inchastrolabe sextantandnauticalmap sinan theancientchinesecompass itwasinventedbyzhanghenginthehandynasty itismadeupofabronzefoundation 青铜地盘 andmagneticspoon 磁勺 whichismadeofnaturalmagnet positionedrightinthecentralofthefoundation thehandleofthespoonpointstothesouth whiletheothersidepointstothenorth whenthesinanisinthestill thehandleofthespoonpointstothesouthbecauseofinfluenceoftheterrestrialmagnetism 地磁 ithas17starslistedaswellasamapoftheskyoverhead for37degrees andtheecliptic 黄道 thetimeofdayornightisontheoutsideedgewithnoonatthetopoftheastrolabeandmidnightatthebottom itcomeswithacarryingchain apouch andabookonitsuse thereversesidehasasightformeasuringtheelevationsoftheheavenlybodies astrolabe sextant thesextantisanavigationalinstrumentformeasuringtheanglebetweenthehorizonandsomeobjectinthesky firstasailorlooksatthehorizonthroughaneyepiece atthesametimehecanseelightfromthesunorastarreflectedoffasmallmirrorontopoftheinstrument ontoasecondmirrorandintotheeyepiece thenavigatorcanthenseetwoimages thehorizonandthesunsidebyside hecanthenmeasuretheanglebetweenthemonascaleatthebottomoftheinstrument thescalegoesfrom0to120degrees anearlierinstrument calledaquadrant measuredinangleinthesamewaybutitcouldonlymeasureanglesfrom0to90degrees nauticalchart nauticalchartsaremapsofthedepthoftheseaandthecurrentsoftheoceans theyprovidemodernsailorswithroutesthroughtheseas ratherlikeroadsthroughthecountryside theinformationbegantobecollectedinthenineteenthcenturyandhascontinuedtobeupdatedeversince thesechartswerenotavailabletocaptainblighorzhenghe 1 howdoyouthinkseamenfoundtheirwaybeforemodernaccuratemethodsofnavigationwereinvented keptclosetotheshore usednaturesuchasthesun wind birds tide etc tohelpthem andusedsomeoftheinstrumentsincludingacompass astrolabe etc 2 whichdoyouthinkwaseasiertoworkout latitudeorlongitude latitude becauseitwasusedtomeasurehowfaryouhadtraveledfromlandonastraightline itwasdiscoveredalongtimebeforelongitude 3 canyouidentifytheseearlynavigationalinstrumentsseamenusedandexplainhowtheyareused 1 compass inancientchina 2 astrolabe3 sextant4 sea nautical marinechart 4 whichonesdoyouthinkarestillusedtoday seachartsarestillusedtoday 1 wheredothesematerialscomefrom 2 whatdidtheearlynavigatorusetohelpthemnavigate 3 whatnaturalobjectswereusedtoassistthenavigation 4 isiteasiertomeasurelongitudeorlatitude 5 dotheastrolabe thequadrantandthesextantmeanthesamething readandanswerthesequestions comprehending 1 readthepassageandanswerthefollowingquestions whatistheuseofabearingcircle astrolabe quadrantorsextant whatistheuseofacompass a tosetthecourseoftheshipb tomeasurethepositionoftheshipc tomeasurethespeedoftheshipd totellthetime a b 2 whyarespeedandtimeimportantinworkingoutthelongitudeofaship speedandtimeareimportantinfindingoutthelongitudeofashipbecausetheearthmovesfifteendegreeswestwardseveryhour ifyouknowyourdirection speedandtime youcanworkouttheapproximatelongitudeorchangeinyourpositioninrelationtothestars 3 whyisthepositionofthesunandvariousstarsusefulforworkingoutlatitude thepositionofthesunandstarsareusefulforworkingoutlatitudebecausetheyarefixedpointsintheskyandtheirmovementsinrelationtotheeartharealreadyknown sotheycanbeusedtomeasureaship sposition 2 supposeyouwereaseacaptainaimingtosailroundafrica discussingroups 1 whatskillswouldyouseekinyoursailors 2 whatproblemswouldyouanticipateforthisjourney waittillthestormisover andthenfindyournewpositionandreturntoyouroriginalcourse 3 readthechartbelowandfillinyourplansofactiontodealwiththem useknotstofindyourspeedandworkoutyourapproximatelongitude usethecompassandtheastrolabe quadrantorsextanttofindoutyourposition returntoyourformercourse follownestingbirdstoshore lookforspecialcloudformationsorfogoverstreamstofindland useacompass measureyourpositionusingthesunorstars lookforseabirds cloudformations fogorsea weedtoshowthatlandisnearby 4 readthepassageagainandusetheinformationtoanalyzethenavigationalskills 1 tofindtheship spositionatseaasailorusedthenorthstarandthesun 2 asailorknewthatlandwasnearbyifhesaw 3 sailorsused toincreasetheirspeed freshseaweed nestingbirdsreturninghomeintheeveningorfog seacurrentsortidesandwinds 4 thereweretwomethodstofindlongitude 1 2 usinginstruments measuringtimeandspeed compassandcomplicatedmathematicaltables 5writedowntheworkingprinciplesofthefollowinginstruments bearingcircle astrolabe tocomparetheheightofthesunnowwiththepositionofthesunatmidday tocomparethepositionoftheshipinrelationtosomestarsorthesun quadrant amorepreciseformoftheastrolabe tomeasurehowhighstarsareabovethehorizon andcomparethatmeasurementwithpreviousmeasurements usingtheshipasoneofthefixedpointstofinditsposition sextant anupdatedversionofthequadrantandsoitwasmoreaccurate tomeasuretheanglebetweentwofixedpointsoutsidetheship usingtwomirrorstofindtheship sposition 5 imagineyouareonaboatwithtwenty nineotherpeople youhaveasmallboxforyourpersonalthingsbutitcanonlyholetenitems whatwouldyouneedforaweek sjourneyacrossthenorthseatoengland soap blanket cards chess shirt trousers knife scissors sea sicktablets coldmedicine novels essaycollections waterproofboots readthepassage reading anddecidewhetherthefollowingstatementsaretrue t orfalse f 1 anearlymethodofcalculatinglongitudewastouseaknottedropetiedtoalog 2 theastrolabewasthefirstinstrumenttomeasurethesun sposition 3 thequadrantwasmorepreciseandsimplifiedthantheastrolabe butstillhaditsshortcoming t f t 4 uptillnow themostaccurateandreliablenavigationalinstrumentisthesextant 5 theastrolabe quadrantandsextantaredifferentkindsofnaviga