Thirty-Hour (One-Day) Marine Chronometer, No. 928

This fine chronometer contains a detachable barrel bridge, a fusee with Harrison’s maintaining power, bimetallic balance, helical balance spring,
and Earnshaw’s spring-detent escapement. It is installed on gimbals inside a two-piece mahogany box, which was also typical of Earnshaw’s chronometers.

Thomas Earnshaw’s spring-detent escapement was the last major contribution needed to make precision chronometers affordable and easy to manufacture. With this invention, he helped make chronometers available to the vast English naval and merchant fleet. The number of chronometers present on ships was a significant factor in the expansion of the British Empire around the world.