French brass marine chronometer with 40 hour power reserve Circa 1840

Brass chronometer by Dumas
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A rare French marine deck Chronometer with spring footed detent and 40 hour power reserve, circa 1840. Made under the direction of Henri Motel. A mahogany deck box, the upper section with a numbered bone plaque, brass case en forme de tabatière secured inside the mahogany box, screwed down brass bezel. Matte silvered dial, radial Roman numerals, outer minute track, subsidiary seconds, power reserve sector below 12 and blued steel Breguet hands. Brass, three quarter plate movement, spotted decoration, reverse fusee and chain, Harrison’s maintaining power. The barrel under a separate bridge, Earnshaw type Chronometer escapement, spring footed detent, two arm cut bimetallic compensation balance with sliding cylindrical temperature weights and meantime adjustment screws, free sprung blued steel helical balance spring, diamond endstone. Dial and movement signed, case numbered.
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Dimensions: 115 x 100 x 67 mm
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Signed: Dumas  Depot De La Marine
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Accompanied by a mahogany box
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The case is slightly scratched