A marine chronometer numbered 8761, by A. Johannsen & Co. It has an eight-day fusee movement with three pillars, all fixed with blued screws. The fusee, with stop-work and Harrison's maintaining power, has a pipe round the winding square. There is an Earnshaw-type spring detent escapement and a two-arm balance with helical balance spring.

The movemet is mounted in a large three-tier mahogany box with a push-catch for lid and lock for upper half. The upper half has a strut limiting opening to 90°. On the front of the upper half is screwed a rectangular tablet inscribed ‘A. JOHANNSEN & Co / 8761 / LONDON’. The box fittings are standard, with flush handles on the sides, brass gimbals and a ratchet-winding key. The bowl has a brass balancing weight on the inside. The dial glass is loose in the bezel. The push-catch and lock are surrounded by shaped brass inserts. There is a shield-shaped brass insert on the box lid. The underside of the box is covered with green baize. Inside the lid is a brass label-holder (empty).

A silvered-brass 24-hour dial has Arabic numerals for all hours and a large seconds dial has Arabic ten-second figures with straight batons at alternate five-second intervals. The dial is inscribed in the centre ‘A. Johannsen & Co., / MAKERS TO THE ADMIRALTY, / THE INDIAN GOVt & ROYAL NAVIES OF / Italy, Spain, & Portugal. / 149 Minories, London.’ In the seconds dial is the number 8761 and the broad arrow. The up-and-down dial, below zero, is marked in Arabic zero to eight except for seven for which is substituted 'WIND'. It is marked 'UP' above zero and 'DOWN' above 'WIND'. The chronometer is in very good condition.

Johannsen & Co. was established in London in circa 1859. Asmus Johannsen was Danish, and made chronometers for the navies of India, Italy, Spain, Portugal, Austria and China. His work was frequently submitted to the Greenwich Trials where it was awarded high marks. It was also submitted to Kew Trials.