Centre-seconds stop-watch with cylinder escapement, in A silver pair-case. The watch is signed 'Geo. Graham London' on the potence plate and cap and inscribed 'W.S.5285' on the outer case.

This stop-watch is believed to have been made for James Bradley, the third Astronomer Royal, who used it for observations on the aberration of light and the fixed stars. The centre-seconds hand can be stopped by moving a small lever which protrudes through the side of the inner case. This actuates a spring which bears on the balance and thus stops the watch.