万物简史英文版_比尔·布莱森-第10章

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cally；　the　lengthwould　shorten　as　you　moved　away　from　the　poles。　this　was　not　good　news　for　those　peoplewhose　measurements　of　the　earth　were　based　on　the　assumption　that　the　earth　was　a　perfectsphere；　which　was　everyone。

for　half　a　century　people　had　been　trying　to　work　out　the　size　of　the　earth；　mostly　bymaking　very　exacting　measurements。　one　of　the　first　such　attempts　was　by　an　englishmathematician　named　richard　norwood。　as　a　young　man　norwood　had　traveled　to　bermudawith　a　diving　bell　modeled　on　halley鈥檚　device；　intending　to　make　a　fortune　scooping　pearlsfrom　the　seabed。　the　scheme　failed　because　there　were　no　pearls　and　anyway　norwood鈥檚　belldidn鈥檛　work；　but　norwood　was　not　one　to　waste　an　experience。　in　the　early　seventeenthcentury　bermuda　was　well　known　among　ships鈥櫋�captains　for　being　hard　to　locate。　theproblem　was　that　the　ocean　was　big；　bermuda　small；　and　the　navigational　tools　for　dealingwith　this　disparity　hopelessly　inadequate。　there　wasn鈥檛　even　yet　an　agreed　length　for　anautical　mile。　over　the　breadth　of　an　ocean　the　smallest　miscalculations　would　beemagnified　so　that　ships　often　missed　bermuda…sized　targets　by　dismaying　margins。　norwood；whose　first　love　was　trigonometry　and　thus　angles；　decided　to　bring　a　little　mathematical　rigorto　navigation　and　to　that　end　he　determined　to　calculate　the　length　of　a　degree。

starting　with　his　back　against　the　tower　of　london；　norwood　spent　two　devoted　yearsmarching　208　miles　north　to　york；　repeatedly　stretching　and　measuring　a　length　of　chain　ashe　went；　all　the　while　making　the　most　meticulous　adjustments　for　the　rise　and　fall　of　the　landand　the　meanderings　of　the　road。　the　final　step　was　to　measure　the　angle　of　the　sun　at　york　atthe　same　time　of　day　and　on　the　same　day　of　the　year　as　he　had　made　his　first　measurement　inlondon。　from　this；　he　reasoned　he　could　determine　the　length　of　one　degree　of　the　earth鈥檚meridian　and　thus　calculate　the　distance　around　the　whole。　it　was　an　almost　ludicrouslyambitious　undertaking鈥攁　mistake　of　the　slightest　fraction　of　a　degree　would　throw　the　wholething　out　by　miles鈥攂ut　in　fact；　as　norwood　proudly　declaimed；　he　was　accurate　to　鈥渨ithin　ascantling鈥濃�攐r；　more　precisely；　to　within　about　six　hundred　yards。　in　metric　terms；　his　figureworked　out　at　110。72　kilometers　per　degree　of　arc。

in　1637；　norwood鈥檚　masterwork　of　navigation；　the　seaman鈥檚　practice　；　was　published　andfound　an　immediate　following。　it　went　through　seventeen　editions　and　was　still　in　printtwenty…five　years　after　his　death。　norwood　returned　to　bermuda　with　his　family；　being　a2how　fast　you　are　spinning　depends　on　where　you　are。　the　speed　of　the　earth鈥檚　spin　varies　from　a　little　over1；000　miles　an　hour　at　the　equator　to　0　at　the　poles。

successful　planter　and　devoting　his　leisure　hours　to　his　first　love；　trigonometry。　he　survivedthere　for　thirty…eight　years　and　it　would　be　pleasing　to　report　that　he　passed　this　span　inhappiness　and　adulation。　in　fact；　he　didn鈥檛。　on　the　crossing　from　england；　his　two　young　sonswere　placed　in　a　cabin　with　the　reverend　nathaniel　white；　and　somehow　so　successfullytraumatized　the　young　vicar　that　he　devoted　much　of　the　rest　of　his　career　to　persecutingnorwood　in　any　small　way　he　could　think　of。

norwood鈥檚　two　daughters　brought　their　father　additional　pain　by　making　poor　marriages。

one　of　the　husbands；　possibly　incited　by　the　vicar；　continually　laid　small　charges　againstnorwood　in　court；　causing　him　much　exasperation　and　necessitating　repeated　trips　acrossbermuda　to　defend　himself。　finally　in　the　1650s　witch　trials　came　to　bermuda　and　norwoodspent　his　final　years　in　severe　unease　that　his　papers　on　trigonometry；　with　their　arcanesymbols；　would　be　taken　as　munications　with　the　devil　and　that　he　would　be　treated　to　adreadful　execution。　so　little　is　known　of　norwood　that　it　may　in　fact　be　that　he　deserved　hisunhappy　declining　years。　what　is　certainly　true　is　that　he　got　them。

meanwhile；　the　momentum　for　determining　the　earth鈥檚　circumference　passed　to　france。

there；　the　astronomer　jean　picard　devised　an　impressively　plicated　method　oftriangulation　involving　quadrants；　pendulum　clocks；　zenith　sectors；　and　telescopes　（forobserving　the　motions　of　the　moons　of　jupiter）。　after　two　years　of　trundling　and　triangulatinghis　way　across　france；　in　1669　he　announced　a　more　accurate　measure　of　110。46　kilometersfor　one　degree　of　arc。　this　was　a　great　source　of　pride　for　the　french；　but　it　was　predicated　onthe　assumption　that　the　earth　was　a　perfect　sphere鈥攚hich　newton　now　said　it　was　not。

to　plicate　matters；　after　picard鈥檚　death　the　father…and…son　team　of　giovanni　andjacques　cassini　repeated　picard鈥檚　experiments　over　a　larger　area　and　came　up　with　results　thatsuggested　that　the　earth　was　fatter　not　at　the　equator　but　at　the　poles鈥攖hat　newton；　in　otherwords；　was　exactly　wrong。　it　was　this　that　prompted　the　academy　of　sciences　to　dispatchbouguer　and　la　condamine　to　south　america　to　take　new　measurements。

they　chose　the　andes　because　they　needed　to　measure　near　the　equator；　to　determine　ifthere　really　was　a　difference　in　sphericity　there；　and　because　they　reasoned　that　mountainswould　give　them　good　sightlines。　in　fact；　the　mountains　of　peru　were　so　constantly　lost　incloud　that　the　team　often　had　to　wait　weeks　for　an　hour鈥檚　clear　surveying。　on　top　of　that；　theyhad　selected　one　of　the　most　nearly　impossible　terrains　on　earth。　peruvians　refer　to　theirlandscape　as　muy　accidentado　鈥斺�渕uch　accidented鈥濃�攁nd　this　it　most　certainly　is。　thefrench　had　not　only　to　scale　some　of　the　world鈥檚　most　challenging　mountains鈥攎ountainsthat　defeated　even　their　mules鈥攂ut　to　reach　the　mountains　they　had　to　ford　wild　rivers；　hacktheir　way　through　jungles；　and　cross　miles　of　high；　stony　desert；　nearly　all　of　it　uncharted　andfar　from　any　source　of　supplies。　but　bouguer　and　la　condamine　were　nothing　if　nottenacious；　and　they　stuck　to　the　task　for　nine　and　a　half　long；　grim；　sun…blistered　years。

shortly　before　concluding　the　project；　they　received　word　that　a　second　french　team；　takingmeasurements　in　northern　scandinavia　（and　facing　notable　disforts　of　their　own；　fromsquelching　bogs　to　dangerous　ice　floes）；　had　found　that　a　degree　was　in　fact　longer　near　thepoles；　as　newton　had　promised。　the　earth　was　forty…three　kilometers　stouter　when　measuredequatorially　than　when　measured　from　top　to　bottom　around　the　poles。

bouguer　and　la　condamine　thus　had　spent　nearly　a　decade　working　toward　a　result　theydidn鈥檛　wish　to　find　only　to　learn　now　that　they　weren鈥檛　even　the　first　to　find　it。　listlessly；　theypleted　their　survey；　which　confirmed　that　the　first　french　team　was　correct。　then；　still　notspeaking；　they　returned　to　the　coast　and　took　separate　ships　home。

something　else　conjectured　by　newton　in　the　principia　was　that　a　plumb　bob　hung　near　amountain　would　incline　very　slightly　toward　the　mountain；　affected　by　the　mountain鈥檚gravitational　mass　as　well　as　by　the　earth鈥檚。　this　was　more　than　a　curious　fact。　if　youmeasured　the　deflection　accurately　and　worked　out　the　mass　of　the　mountain；　you　couldcalculate　the　universal　gravitational　constant鈥攖hat　is；　the　basic　value　of　gravity；　known　asg鈥攁nd　along　with　it　the　mass　of　the　earth。

bouguer　and　la　condamine　had　tried　this　on　peru鈥檚　mount　chimborazo；　but　had　beendefeated　by　both　the　technical　difficulties　and　their　own　squabbling；　and　so　the　notion　laydormant　for　another　thirty　years　until　resurrected　in　england　by　nevil　maskelyne；　theastronomer　royal。　in　dava　sobel鈥檚　popular　book　longitude；　maskelyne　is　presented　as　a　ninnyand　villain　for　failing　to　appreciate　the　brilliance　of　the　clockmaker　john　harrison；　and　thismay　be　so；　but　we　are　indebted　to　him　in　other　ways　not　mentioned　in　her　book；　not　least　forhis　successful　scheme　to　weigh　the　earth。　maskelyne　realized　that　the　nub　of　the　problem　laywith　finding　a　mountain　of　sufficiently　regular　shape　to　judge　its　mass。

at　his　urging；　the　royal　society　agreed　to　engage　a　reliable　figure　to　tour　the　british　islesto　see　if　such　a　mountain　could　be　found。　maskelyne　knew　just　such　a　person鈥攖heastronomer　and　surveyor　charles　mason。　maskelyne　and　mason　had　bee　friends　elevenyears　earlier　while　engaged　in　a　project　to　measure　an　astronomical　event　of　great　importance：

the　passage　of　the　planet　venus　across　the　face　of　the　sun。　the　tireless　edmond　halley　hadsuggested　years　before　that　if　you　measured　one　of　these　passages　from　selected　points　on　theearth；　you　could　use　the　principles　of　triangulation　to　work　out　the　distance　to　the　sun；　andfrom　that　calibrate　the　distances　to　all　the　other　bodies　in　the　solar　system。

unfortunately；　transits　of　venus；　as　they　are　known；　are　an　irregular　occurrence。　theye　in　pairs　eight　years　apart；　but　then　are　absent　for　a　century　or　more；　and　there　were　nonein　halley鈥檚　lifetime。

3but　the　idea　simmered　and　when　the　next　transit　came　due　in　1761；nearly　two　decades　after　halley鈥檚　death；　the　scientific　world　was　ready鈥攊ndeed；　more　readythan　it　had　been　for　an　astronomical　event　before。

with　the　instinct　for　ordeal　that　characterized　the　age；　scientists　set　off　for　more　than　ahundred　locations　around　the　globe鈥攖o　siberia；　china；　south　africa；　indonesia；　and　thewoods　of　wisconsin；　among　many　others。　france　dispatched　thirty…two　observers；　britaineighteen　more；　and　still　others　set　out　from　sweden；　russia；　italy；　germany；　ireland；　andelsewhere。

it　was　history鈥檚　first　cooperative　international　scientific　venture；　and　almost　everywhere　itran　into　problems。　many　observers　were　waylaid　by　war；　sickness；　or　shipwreck。　others　madetheir　destinations　but　opened　their　crates　to　find　equipment　broken　or　warped　by　tropical　heat。

once　again　the　french　seemed　fated　to　provide　the　most　memorably　unlucky　participants。

jean　chappe　spent　months　traveling　to　siberia　by　coach；　boat；　and　sleigh；　nursing　his　delicateinstruments　over　every　perilous　bump；　only　to　find　the　last　vital　stretch　blocked　by　swollen3the　next　transit　will　be　on　june　8；　2004；　with　a　second　in　2012。　there　were　none　in　the　twentieth　century。

rivers；　the　result　of　unusually　heavy　spring　rains；　which　the　locals　were　swift　to　blame　on　himafter　they　saw　him　pointing　strange　instruments　at　the　sky。　chappe　managed　to　escape　withhis　life；　but　with　no　useful　measurements。

unluckier　still　was　guillaume　le　gentil；　whose　experiences　are　wonderfully　summarizedby　timothy　ferris　in　ing　of　age　in　the　milky　way　。　le　gentil　set　off　from　france　a　yearahead　of　time　to　observe　the　transit　from　india；　but　various　setbacks　left　him　still　at　sea　on　theday　of　the　transit鈥攋ust　about　the　worst　place　to　be　since　steady　measurements　wereimpossible　on　a　pitching　ship。

undaunted；　le　gentil　continued　on　to　india　to　await　the　next　transit　in　1769。　with　eightyears　to　prepare；　he　erected　a　first…rate　viewing　station；　tested　and　retested　his　instruments；and　had　everything　in　a　state　of　perfect　readiness。　on　the　morning　of　the　second　transit；　june4；　1769；　he　awoke　to　a　fine　day；　but；　just　as　venus　began　its　pass；　a　cloud　slid　in　front　of　thesun　and　remained　there　for　almost　exactly　the　duration　of　the　transit：　three　hours；　fourteenminutes；　and　seven　seconds。

stoically；　le　gentil　packed　up　his　instruments　and　set　off　for　the　nearest　port；　but　en　routehe　contract