Swiss gold minute repeating lever pocket watch Circa 1856

Gold open faced minute repeater by Vacheron & Constantin
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A Swiss 18 carat gold open faced minute repeating key wind pocket watch, circa 1856. Gilded brass movement, going barrel, straight line equilibrated lever escapement, compensated balance with gold poising screws and blued steel hairspring with terminal curve, minute repeater on two steel gongs activated by the slide at 3 o’clock. White enamel dial with Roman hours and Arabic minutes. Case guilloché engine turned to the back, the centre engraved in tailledouce (fine cut) with a cypher. Cuvette signed, case and movement numbered. Comes with fitted box and Extract from the Archives.
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Diameter: 46.5 mm
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Signed: Vacheron & Constantin