Swiss silver open faced lever chronograph watch Circa 1919

Silver chronograph by Vacheron & Constantin
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A Swiss silver open faced keyless lever chronograph, circa 1919. Gilt finished lever movement, 20 jewels, bimetallic compensation balance, swan neck regulator. Silver cuvette. White enamel dial with Arabic numerals, outer calibrated fifth seconds ring with red Arabic fifth divisions and sunken subsidiary dial for constant seconds. Polished case, chronograph operated through the crown, hinged back. Case, cuvette, dial and movement signed, case and cuvette stamped HF, case and movemen numbered.
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Diameter: 52 mm
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Signed: Vacheron & Constantin Genève Corps of Engineers U.S.A.