[ti:13]
[ar:阅读法]
[00:00.533]13、Archimedes  and  the  Gold  Crown
[00:02.983]Archimedes  was  a  famous  Greek  scientist.
[00:04.833]He  is  regarded  as  one  of  the  leading  scientists  in  classical  era.
[00:10.184]He  was  also  a  great  inventor
[00:12.584]and  is  given  credit  for  many  inventions  and  discoveries.
[00:15.735]One  of  his  best-known  contributions  to  science  is  Archimedes ’principle.
[00:21.35]There ’s  an  interesting  story  behind  it.
[00:23.335]The  tale  goes  as  follows.
[00:25.288]Over  two  thousand  years  ago,
[00:26.989]on  the  island  of  Sicily  lived  a  rich  king  called  Heron.
[00:31.659]The  king  had  a  golden  crown  which  was  supposed  to  be  made  of  pure  gold.
[00:36.661]But  the  king  had  a  suspicion  that  the  crown  contained  some  cheaper  metals  like  silver.
[00:40.668]To  prove  his  suspicion,
[00:43.930]the  king  asked  Archimedes  to  check  the  golden  crown  to  see
[00:46.993]if  it  was  really  made  of  pure  gold,
[00:49.395]but  the  crown  could  not  be  harmed  or  damaged  in  any  way.
[00:53.245]As  Archimedes  contemplated  this  difficult  problem  in  his  house,
[00:57.197]his  servant  prepared  a  bath  for  him.
[00:59.748]The  bathtub  was  filled  with  water  to  the  very  brim
[01:03.300]and  Archimedes  stepped  into  his  bath.
[01:06.150]As  he  sat  down  into  the  tub  fully,
[01:08.751]he  noticed  water  spilling  over  the  edge  of  the  tub.
[01:12.351]He  suddenly  discovered  the  relation  between  the  water
[01:15.204]that  fallen  out  and  the  weight  of  his  body,
[01:18.157]and  knew  the  method  to  solve  the  crown  problem.
[01:21.359]Archimedes  was  so  excited  with  his  discovery
[01:23.859]that  he  jumped  out  of  bath  and  ran  naked  into  the  street,
[01:27.812]yelling “Eureka!”（Greek  word  for “I ’ve  found  it!”）
[01:32.514]Archimedes  realized  that
[01:33.815]his  body  occupying  space  in  the  tub  had  displaced  its  own  weight  of  water  from  the  bath.
[01:40.615]All  he  had  to  do  is  put  the  gold  crown  into  a  vessel  with  water  to  the  very  brim.
[01:46.716]If  the  overflow  of  water  was  equal  to  the  volume  of  an  equal  mass  of  pure  gold,
[01:52.121]the  crown  would  be  made  of  pure  gold.
[01:54.171]If  not,the  crown  might  contain  some  cheaper,materials.
[01:58.371]And  after  the  experiment,
[01:59.374]it  was  clear  that  the  crown  contained  some  cheaper  metals.
[02:03.282]This  is  where  Archimedes ’Principle  comes  from.