Interesting Swiss silver chronograph pocket watch Circa 1918

Silver watch made for the U.S. Army Corps of Engineers
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An interesting Swiss silver keyless pocket watch with a chronograph, circa 1918. Made for the U.S. Army Corps of Engineers. A polished case, the back engraved Corps of Engineers U.S.A. No. 1225 and a hinged silver cuvette. White enamel dial with bold luminous upright Arabic numerals, outer Arabic minute and chronograph ring and subsidiary seconds and luminous blued steel skeleton hands. Frosted gilt brass movement, twenty jewels, straight line lever escapement, cut bimetallic compensation balance, blued steel Breguet balance spring, swanneck micrometre regulator, chronograph with visible work, the button on the winding crown. The dial is signed.
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Diameter: 52 mm
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Signed: Vacheron & Constantin  Genève