German important astronomical silver pocket watch Circa 1780

Open faced pocket watch by Philipp Matthäus Hahn
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A gentleman’s important astronomical German pocket watch, circa 1780.
Silver tiered plain case. Signed enamel dial with centre seconds, blued hands and three auxiliary dials: hours and minutes, the date in combination with the planetary days and the moon phases in combination with the time from moonrise to moonset; the last is divided into quarters of the night (red Arabic numerals on the left half of the dial, black Arabic numerals on the right half). Full plate movement, firegilt, engraved, conical movement pillars, open barrel, pierced engraved balance bridge with regulator scale, large brass balance, cylinder escapement.
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Diameter: 61 mm
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Weight: 213 g
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Signed: Hahn à Echterdingen
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Philipp Matthäus Hahn (1739 – 1790) Hahn was a German priest and inventor. In 1773 he designed the first functional mechanical calculator. A renowned clockmaker, several horological museums display his works, including the Deutsches Uhrenmuseum which contains a mechanical orrery (planetarium) and a Weltmaschine by the “Priestermechaniker (priest mechanic)”.