Time ball
A time ball or timeball is a time-signalling device. It consists of a large, painted wooden or metal ball that is dropped at a predetermined time, principally to enable navigators aboard ships offshore to verify the setting of their marine chronometers. Accurate timekeeping is essential to the determination of longitude at sea.
Although time balls have since been replaced by electronic time signals, some time balls have remained operational as historical tourist attractions.
Clock tower, Margate, Kent, UK
