Swiss U.S. Army Corps of Engineers chronograph Circa 1918

Silver open faced military chronograph by Vacheron & Constantin
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A fine and interesting Swiss silver open faced military lever pocket watch with chronograph made for the U.S. Army Corps of Engineers, circa 1918. Rhodium-plated movement, 20 jewels, straight-line lever escapement, cut bimetallic compensation balance, blued steel Breguet balance spring, swan-neck micrometre regulator, visible chronograph work, co axial chronograph button on the winding crown. Hinged silver cuvette. White enamel dial with luminous bold Arabic numerals, outer minute track and fifths of a second chronograph divisions, subsidiary seconds dial and original blued steel skeleton hands. Solid, polished case, the back with Corps of Engineers inscription. Dial, case, cuvette and movement signed, case and movement numbered.
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Diameter: 52 mm
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Signed: Corps of Engineers U.S.A. Vacheron & Constantin Genève
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This watch was produced especially for the U.S. Army Corps of Engineers, founded in 1775 by the Continental Congress. The Corps requested a watch for field use, with a silver case, a white dial with luminous Arabic numerals and hands, and a simple chronograph movement without counter.