Congreve Rolling Ball Clock
Replica Congreve clock by Dent of London, 1973
Born in 1772, William Congreve was the son of a Baronet, to whose title he succeeded in1814. In 1791 he joined his father at the Royal Laboratory in Greenwich and was to achieve fame as the inventor of the Congreve Rocket. He would later go on to command a rocket company at the battle of Leipzig in 1812. Congreve became a Fellow of the Royal Society and a Member of Parliament. In 1814 he succeeded his father as Comptroller of the Royal Laboratory. Sir William Congreve died in 1828.
Although probably not a clock maker himself, Congreve was a gifted horologist and produced two ingenious clock designs: the rolling ball clock and a movement that he described as having an ‘extreme detached escapement’. The first example of the rolling ball design was made for him, possibly by Gravel and Tolkien, and patented in 1808. This was later presented to the Prince Regent who subsequently presented it to the Royal Regiment of Artillery (of which Congreve was an Officer). It is in the Museum of Artillery at the Woolwich Rotunda.
The movement of this spring driven clock is controlled by a steel ball running in a zig-zig groove, cut in a flat plate, which tilts first in one direction, then the other. In this example the ball completes its run in 15 seconds. On arrival at the end of the groove the ball moves a pivoted lever which releases the going train of the clock, the hands advance by 15 seconds and the table tilts in the opposite direction. The ball then starts its return journey and the cycle is repeated. The table and ball thus act as the clock’s escapement. During the balls run no other part of the clock is in motion.