A ship's chronometer, two-day duration with Arnold type spring detent escapement and fusee and chain movement in gimbals, silvered and engraved dial marked 'French, Royal Exchange, London, No.5156' (i.e. Santiago James Moore French), signature and serial number boldly repeated on back plate, bimetallic two-arm balance with helical blued steel balance spring and diamond endstone, wedge-shaped poising weights, blued steel hands. 9 cm diameter bezel with convex bevelled glass. Three-part brass-bound mahogany case, '5156' engraved and filled on inset ivory plaque in middle part. Ratchet winding key is mounted on winding arbor below bowl. c. 1830