The Time ball clock is another way to give time remotely, like the one on the roof of the Royal Greenwich Observatory. “A time ball is a large ball that can slide along a vertical mast, which is dropped at predetermined times to indicate the time in a public way. Therefore, the time balls are placed high enough to be visible from a distance: usually at the top of a tower or sometimes a lighthouse. They are usually made of painted wood or metal. The masts bearing the time balls are often topped with a weathervane and a directional cross indicating the four cardinal points.” (Wikipedia)
