Swiss keyless dress watch with digital jumping hours Circa 1925

Silver and enamel dress watch
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A fine and very rare Swiss silver and enamel open faced keyless lever dress watch with wandering digital jumping hours made to the patent design of Robert Cart, Le Locle, circa 1925. The movement is an ébauche by Robert Cart with Geneva Striping decoration, 18 jewels, straight-line lever escapement, cut bimetallic compensation balance, index regulator, blued steel Breguet spring, index regulator. The dial with a fixed mat silver ring with Arabic minute numerals, the time indicated by a revolving engine-turned central disc with an arrow and the digital jump hour visible in an aperture pierced through the point of the arrow. A polished case, the bezel, band, pendant and back are inlaid with black champlevé enamel. Dial and movement signed and numbered, case numbered.
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Diameter: 43 mm
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Signed: Breguet Breveté S.G.O.G. France