Watch with seconds dial by Thomas Tompion

In 1675 Dr Robert Hooke and Christiaan Huygens independently introduced the balance spring to watches, which meant that they could be much more precise, capable of being accurate to within less than a minute per day.

This new technology was one of the factors that contributed to a change in attitude towards time and timekeepers, and there was an immediate demand for these new precision instruments. This gave rise to a series of watches with a seconds hand. Although not the first watch to have such a feature, this one is an early example.

The watch has a fusee and a verge escapement with steel balance and spiral steel balance spring. The dial shows hours and minutes in the usual way on a silver champlevé dial but has the unusual addition of a subsidiary seconds dial. There is also a stop-lever, which, used with the seconds dial, enables it be used as a stop-watch.

The watch is housed in a plain silver inner case with the case-maker's mark (ND conjoined) of Nathaniel Delander, one of the most accomplished case-makers of the time. The back-plate is signed 'Tho Tompion London 4' with two punched arrow head marks, each denoting 500 in Tompion's coded system, making a total serial number of 1004. The brass-covered tortoise-shell outer case is inlaid in silver piqué posé with a design of foliate scrolls, birds and a squirrel.