Balance spring pocket watch in silver case, 1675-1679.

This pocket watch is one of the earliest surviving balance spring watches. Made by the great English clock maker Thomas Tompion (1639-1713), it has a Tompion-type regulator dial and a separate seconds hand. The application of the pendulum in 1657 to clock timekeeping, which was of such huge significance to horology and science, was matched by the application of the balance spring in 1675 to watch timekeeping. Both devices offered far more accurate timekeeping than had previously been posible. In 1675, under the supervision of leading scientist Robert Hooke (1635-1703), Tompion made one of the first English watches equipped with a balance spring, a watch which was presented to Charles II (1630-1685).