Swiss gold lever chronograph with pulsation Circa 1920

Hunting cased keyless chronograph by Girard-Perregaux
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A Swiss 18 carat gold hunting cased keyless lever chronograph pocket watch with pulsation scale, circa 1920. Nickel finished jewelled lever movement, bimetallic compensation balance. Gold cuvette. White enamel dial with Breguet numerals, outer calibrate fifth seconds ring with red Arabic fifth seconds divisions, calibrated pulsation scale, two sunken subsidiary dials for 30 minute register and constant seconds, blued steel hands. Polished case, monogrammed front cover, chronograph operated through a button in the band. Case, cuvette, dial and movement signed, case and cuvette numbered.
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Diameter: 52 mm
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Signed: Girard-Perregaux Chaux-de-Fonds