French wandering digital jumping hours watch Circa 1925

Silver digital keyless lever watch 
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A fine and very rare French silver and enamel open faced keyless lever dress watch with wandering digital jumping hours made after the patent design of Robert Cart, Le Locle, circa 1925. The movement an ébauche by R. Cart, 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, black Arabic five-minute numerals, the time indicated by a revolving central engine-turned disc with an arrow, the digital jump hour is visible in an aperture pierced through the point of the arrow at 12 o’clock. 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