Model of Earnshaw's Spring Detent Escapement

This model has a plain three-arm balance, over-coiled balance spring, steel impulse and locking pallets, key wound through the turned ebonized wood base.

Thomas Earnshaw developed his spring detent escapement for chronometers, building upon the work of John Arnold. Earnshaw simplified the mechanism, which made it easier and more affordable to produce, making chronometers readily available on the seas.