Swiss silver keyless pocket watch with chronograph Circa 1918

Silver open faced lever watch
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A fine and interesting Swiss keyless, silver pocket watch with chronograph, circa 1918. Made for the U.S. Army Corps of Engineers. Polished bassine, dedicated hinged silver cuvette. White enamel dial with bold Arabic numerals, outer five-minute/seconds Arabic and 1/5th seconds chronograph scales, subsidiary seconds dial. Blued steel skeleton hands. Chrono, rhodium-plated movement, partial oeil-de-perdrix decoration, 20 jewels, straight line lever escapement, cut bimetallic compensation balance, blued steel Breguet balance spring, swan-neck micrometer regulator, chronograph button on the winding crown. Dial, case and movement signed.
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Diameter: 52 mm
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Signed: Vacheron & Constantin Genève