J. Sewill Detent Boxed Chronometer. English, fusee detent boxed chronometer with blued helical spring and retaining power, 4 in. silvered dial, black Roman hour numerals, Arabic 5 minute markers, half moon up-down indicator and 1.5 in. sub seconds dial, signed J. Sewill, 30 Cornhill, London, Royal Exchange, Maker to the Admiralty, 4653; Gold spade and diamond hands with good gimbaled brass tub, bezel with glass crystal and all hardware. In very good condition, dial is clean, movement is in good running condition, good fusee chain; in original rosewood case with brass inlays, handles, key and mother of pearl plaque signed by the maker. Box is 7.5 high x 7 in. wide x 7 in. deep