††A pendulum is a swinging wire or rod with a weight on the end.
It is said that in 1581, Galileo discovered the principle of the pendulum whilst watching the sway of lamps in a cathedral. Galileo worked out that a pendulum swings at a constant oscillation, and was therefore an ideal device for a clock which requires a regularity of movement in order to keep time. He developed his idea further, and an example of a pendulum- controlled clock was finally built by his son Vincenzio Galilei in 1641.
