French silver complicated astronomical cylinder watch Circa 1800

One of the earliest known astronomical watches
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A technically rare and one of the earliest known French silver open faced astronomical cylinder pocket watch with a real perpetual calendar, Quantième Bisextile, circa 1800. Full plate movement, cylinder escapement, chain/fusee. Original white enamel dial with Arabic numerals, inscribed Bisextile, an indication of the time with seconds and six astronomical complications, among them the extremely rare perpetual calendar with 4 × 12 months, weekday, date, the month with indication of the month length of 28-31 days, moon phase and moon age, rose gold hands. Engine turned case, blanc cartouche to the back, with French punches. Case and movement with matching punches, case numbered.
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Diameter: 57 mm
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Weight: 113 g
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Signed: No name
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Pocket watches with a perpetual calendar from before 1850 are absolute rarities.