Electric impulse dial by Synchronome. The brass and steel movement is designed to indicate concentric seconds and minutes, the seconds advancing in two second intervals, the white-painted dial with Arabic five second/minute figures. There is also a subsidiary twenty-four hour dial with Arabic hour figures (‘0’ for 24) which can be independently set from behind. The dial is signed: ‘SYNCHRONOME LONDON’ across the centre. The second and minute hands are missing. The oak dial surround would originally have had a brass bezel with flat glass over the dial, now missing.

A number of 'sympathetic' or 'impulse' dials such as this were made for the Royal Observatory at the end of the 19th century and into the 20th century, to increase the availability of GMT in the various rooms in the buildings at Greenwich. Although not made to Shepherd's specification, this clock was almost certainly intended for use as part of the Shepherd system at the Observatory.