Important French brass marine deck chronometer Circa 1840

Brass chronometer by Louis Berthoud
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An extremely rare and important French brass marine deck chronometer pocket in a mahogany box, circa 1816. A brass case with a dedication engraved on the inner dome: Dépot général de la marine. White enamel dial regulator type with a small eccentric Roman chapter for hours, subsidiary seconds below, outer Arabic minute ring on the border of the bezel. Blued steel Breguet hands. Frosted and gilt, full plate movement, with conical pillars secured by blued steel nuts with polished steel washers, fusee and chain with maintaining power, counterpoised straight line lever escapement with rollers on the balance staff. Three armed compensation balance with three weights, and three additional weights and platinum timing screws. Free sprung blued steel conical spring with adjustable collar. Signed on the back plate and the dial rim, Par Ls. Berthoud No. 145 and on the dial, Louis Berthoud No. 145.
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Diameter: 82 mm
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Box: 133 x 133 x 110 mm
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Signed: Louis Berthoud  Dépot général de la marine
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Accompanied by a mahogany box