Rare Swiss nickel cylinder watch with decimal time Circa 1850

Nickel open faced decimal time watch
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An extremely rare nickel open faced cylinder pocket watch, Décimale Métrique, made by Moll, Bienne, Switzerland, circa 1850. Keywound cylinder movement. Original white enamel dial with black Arabic decimal hours, an outer minute track and blued steel hands. A polished case. Dial signed.
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Diameter: 55 mm
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Weight: 123 g
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Signed: Moll Ingénieur Bienne