Swiss 18 carat gold doctors watch with register Circa 1915

Rare gold collector’s doctor watch with open face by Longines
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A fine Swiss 18K gold doctor’s watch with a nickel-finished lever movement and flyback centre seconds chronograph, circa 1915.
Very fine anchor chronometer movement with special fine adjustment, chronograph, and Geneva stripes. Signed original enamel dial with red pulsometer scale, Breguet-style radial hours, outer minutes/seconds track with Arabic five minutes/seconds numerals, subsidiary dial for the seconds, 30-minute counter, centre chronograph hand, and blued steel Breguet-style hands. Plain polished 18K gold case. Case and movement with matching numbers.
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Diameter: 48 mm
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Weight: 75 g
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Signed: Longines
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Working: A doctor measures the heartbeat by starting the chronograph and counting to 30 beats, and then stopping the chronograph; then, he can see the heartbeat on the right side of the dial.