Swiss gold chronograph with tachymeter scale Circa 1918

Gold keyless lever chronograph with register by Vacheron & Constantin
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A fine and rare Swiss 18 Carat gold keyless lever dress watch with chronograph, instantaneous 30 minute register and outer tachymeter scale, circa 1918. Frosted gilt movement, 21 jewels, straight-line lever escapement, cut bimetallic compensation balance, blued steel Breguet balance spring, swan neck micrometre regulator. Hinged gold cuvette. White enamel dial with black Breguet numerals, outer tachymeter scale calibrated for 1000 meters, 30 minute register at 12, subsidiary seconds at 6 0’clock and original gold spade hands. Solid, polished case, semi concealed hinge, with London import marks for 1939. Dial, case and movement signed, case and movement numbered.
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Diameter: 53 mm
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Signed: Vacheron & Constantin Genève