This clock was in use at St Helena as the Transit Clock in 1833. It returned to Greenwich in 1836, when Astronomer Royal, George Biddell Airy, described its condition as ‘very foul’. After cleaning at Barraud’s premises the clock was tested and then shipped to the Royal Observatory, Cape of Good Hope.

The movement has angled corners to the plates, which are united by six screwed baluster pillars. The movement, which has a fine train with high numbered pinions is driven by polished brass cased weight suspended via a six-spoked pulley wheel and double line on the going barrel, which is cut with 17 turns. The dead-beat escapement has steel pallets fitted with sapphire nibs and a delicate brass escape wheel, which is mounted to its collet by three screws. Where possible all pivots have screwed end caps. The silvered brass dial is 255mm in diameter and is laid in the typical regulator form with outer minute ring enclosing the subsidiary hour and second dials. Within the seconds dial there is a small circular aperture for viewing the action of electrical contacts (subsequently removed). The mercury type temperature compensated pendulum is suspended from a brass Troughton support and is visible through the glazed trunk door. The mahogany case has a flat-topped hood with ripple moulded cornice over canted corners that flank the glazed dial aperture and trunk door. The interior of the clock has been painted white.