This unusual stop watch records short intervals of time to tenths of seconds and it belonged to the 5th Astronomer Royal, Nevil Maskelyne. We know from his memoranda that Maskelyne received the watch from its maker, William Coombe, July 17th, 1786. Very little is known about William Coombe. He first came to Maskelyne’s attention when he submitted a timekeeper for trial at the Royal Observatory in 1779 and was subsequently commissioned by Maskelyne to make an astronomical regulator for the Grand Duke of Tuscany’s observatory.

The gilt brass case has a shuttered winding hole to the rear and hinged bezel with domed glass. The 2.75-inch dial has an unconventional layout, with three dials reading: minutes, seconds and tenths of seconds. The watch, designed for short interval timing, has a stop/start lever set within the brass edge to the left of the maker’s signature. The four wheel full-plate movement has a simple cylinder type escapement and small brass balance, which beats 36,000 times per hour. The frame is united by cylindrical pinned pillars; the potence plate is signed, dated and features a broad graduated scale for the index.