Lesson 71 A famous clock
After the Houses of Parliament were burnt down in 1834,Sir Benjamin Hall was made responsible for the construction of a huge clock,which became known as Big Ben.It is very accurate despite its immense size,for offcials from the Greenwich Observatory have the clock checked twice a day.This clock,which has rarely gone wrong,can be heard on the B.B.C.when it is striking,because microphones are connected to the clock tower.