Regulator clock made by Benjamin Vulliamy for King George III, London, 1780. Used at the King's Observatory at Kew. In polished mahogany case, with a side plate and glass top for case

A regulator clock is a highly accurate timepiece, usually used for making precise measurements in conjunction with astronomical observation. This is the movement from a clock made by Benjamin Vulliamy (1747-1811) in 1780 for King George III and used as the principal timekeeper at the King's Observatory at Kew. Rollers act as the bearings for the wheelwork, reducing the friction and the need for lubrication. For similar reasons the clock was also fitted with the grasshopper escapement invented by the pioneer of the chronometer, John Harrison (1693-1776). Harrison`s gridiron pendulum was also incorporated to ensure that the clock kept good time by compensating for changes of temperature.