Chronometer with patented micrometric regulator Circa 1899

Rose gold open faced pocket chronometer by Vacheron & Constantin
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Very fine Swiss 18 carat rose gold open faced keyless wind pocket chronometer with a patented micrometric regulator, circa 1899. Gilded brass movement with going barrel, straight line equilibrated lever escapement, compensation balance with gold poising screws and blued steel hairspring with a terminal curve, adjusted by a precision timer with device for fast/slow using a micrometric screw. White enamel dial with Roman hours and Arabic minutes, subsidiary seconds at 6. Plain case, hinged back. Case and movement signed and numbered. Comes with 18 carat gold chain.
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Diameter: 50 mm
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Signed: Vacheron & Constantin