Rare Swiss 18k gold astronomical pocket watch Circa 1870

Gold open faced astronomical watch
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A very fine and very rare, astronomic 18k gold Swiss, eight-day going, two-train pocket watch, circa 1870. With day, date, moon phases and indication for the diurnal and nocturnal hours. Mastermark ‘FS’, polished and engine-turned, the back cover with a vacant foliate bordered cartouche. Hinged gold cuvette.

White enamel dial with radial Roman numerals, outer minute track, subsidiary dials for the day of the week, the date, seconds and diurnal and nocturnal hours, aperture for the moon phases. Gold Spade hands. Frosted gilt movement, bar calibre, two going barrels, 12 jewels, cylinder escapement, three-arm gold balance, blued steel flat balance spring, index regulator. Movement signed. Case and movement numbered.
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Diameter: 50 mm
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Signed: Soudan Genève
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The present watch is exceptionally unusual in that it combines eight-day going with day, date, moon phases, and 24-hour indication. Very few watches featuring these complications are known from this period.