Fine Swiss silver keyless chronograph pocket watch Circa 1920

Silver open faced doctor’s watch
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A fine Swiss sterling silver open faced keyless pocket watch with chronograph, instantaneous 30 minute register and pulsometer made by Longines in Saint-Imier, circa 1920. Engine turned case back with a monogram. A solid case with a polished, hinged cuvette engraved with various prize medals. White enamel dial with bold black Arabic hours, outer minute and fifth of a second track with red Arabic five minute numerals, an outermost red pulsometer scale graduated to 30 pulsations, subsidiary seconds at 6 o’clock, a 30 minute counter at 12 and blued steel spade hands. Rhodium plated movement with a straight line lever escapement, 21 jewels, a monometallic balance with screws and Breguet balance spring. Dial, case and movement are signed.
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Diameter: 54 mm
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Signed: Longines Swiss