Unusually small Swiss cylinder watch with digital dial Circa 1900

Silver open faced cylinder watch 
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An unusually small Swiss silver open faced cylinder pocket watch with a digital dial, circa 1900. Keyless gilt bar movement with going barrel, plain cock with polished steel regulator, plain gilt balance with blue steel spiral hairspring, polished steel cylinder and steel escape wheel. White enamel dial signed Patent within an engraved silver hexagonal mask, polychrome floral decoration on either side of the central aperture revealing the digital indication of minutes, a circular aperture above showing the hours. The minutes change instantaneously. Case chased and engraved with a vacant shield-shaped cartouche on the back.
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Diameter: 40 mm
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Signed: No name