Bong! Big Ben turns 150
The 4.2 meter- (14 foot-) long minute hand casts a faint shadow over the pale white glass of the dial. The 5-ton (5.6-U.S. ton) clock mechanism, like a giant wristwatch, is wound three times a week. In the age of atomic clocks, its near-perfect time is regulated by heavy old pennies laid on or removed from the pendulum. Above, a cleaning in 2001. AP file
