French 36 hour deck chronometer with power reserve Circa 1840

36 Hour deck chronometer by Jean Aimé Jacob
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A fine and rare French 36 hour going deck chronometer with power reserve indication in a mahogany box, circa 1840. A circular gilt brass movement with the plates pinned to cylindrical pillars, Ø 61 mm, fusee and chain with Harrison’s maintain power, an 18.000 count train, Earnshaw’s chronometer escapement on a further plate on the backplate, a spring footed detent, jewelled locking stone, bi metallic compensation balance with two cylindrical weights and meantime and temperature adjustment screws, a free sprung blued steel helical balance spring with inner and outer terminal curves, diamond end stone. Silvered brass dial with champlevé Roman hours, outer dot minute divisions, subsidiary seconds at six o’clock, an up and down sector at three o’clock and blued steel Breguet hands. A three tier mahogany deck box, the chronometer fixed in a brass dial plate in the middle section secured by eight screws, brass drum housing for the movement with a shuttered winding hole, glazed brass bezel with two screws in the side. Dial signed.
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Dimensions: 10 x 12.5 x 7 cm
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Signed: Dépôt de la Marine Ame Jacob à St Nicolas No 262
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Jean-Aimé Jacob was born in 1793 and died in 1871. He was a French maker of repute being listed for chronometers, regulators and astronomical clocks. Silver medal in 1844. In 1856 he exhibited an astronomical clock in Rouen.