The Congreve Clock

A Congreve clock is a timepiece which works based on the movement of a ball rolling down a track in various zigzagging patterns. This is used instead of a pendulum to regulate the count of time. It takes its name from its inventor, Sir William Congreve, who invented the clock in 1808.

The way the clock works is that a ball is set to roll down a track of specified length. The ball takes a specific amount of time to reach the end of this track, usually between fifteen and thirty seconds, where it then trips the escarpment. This reverses the trays tilt which in turn moves the hands of the timepiece forward.

The result is a clock whose minute hands move forward between one and four times every minute. If second hands are attached they jump forward between 15 and 30 seconds on each tick of the clock.

Congreve’s design is actually not the first example of a rolling ball clock. Earlier versions had been developed both by Nicolas Grollier de Servière and Johann Sayller. It does not appear that Congreve was aware of these earlier designs, however his own work did improve on them both somewhat, in that his clock used just a single ball, moving down a zigzag track, rather than multiple balls moving down single track systems.

Congreve patented the design of his clock in 1808, and then since he was not himself a clock maker by trade, he hired Gravel and Tolkein to produce the first model piece for him. This first model was given to the Prince of Wales later that year.

A later model, built by John Moxon, appears to have improved on his own design. This clock was built based on a spring driven, rather than a weight driven model, which improved its accuracy to some extent.

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