John Ellicott

John Ellicott was a prominent London clock- and instrument-maker, Fellow of the Royal Society, and holder of the position of Clockmaker to King George III, whose workshop produced precision domestic and scientific clocks during the mid-eighteenth century alongside barometers and other scientific instruments, situating him within the same milieu of Royal Society-connected instrument makers as contemporaries pursuing improved timekeeping for astronomy and navigation.

Ellicott is credited with an important improvement to the compensation pendulum, devising a compensating pendulum mechanism (distinct from John Harrison's gridiron design) using differential expansion of brass and steel to keep the pendulum's effective length, and therefore its rate, more constant across temperature changes, a refinement described in his own published paper to the Royal Society and generally regarded as a genuine and well-documented eighteenth-century contribution to precision pendulum clockmaking.

His business also engaged in the export trade to European courts and colonial markets, and the Ellicott family workshop continued under his son Edward Ellicott after John's death, maintaining the firm's reputation for high-quality precision and decorative clockwork into the later eighteenth century.