Philipp Matthäus Hahn
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Philipp Matthäus Hahn (25 November 1739 in Scharnhausen (today part of Ostfildern), Duchy of Württemberg – 2 May 1790 in Echterdingen (today part of Leinfelden-Echterdingen)) was a German pastor, astronomer and inventor.
In about 1763 he devised a precision sundial, or heliochronometer that incorporated the correction for the equation of time.[1]
In 1774[2] he designed one of the earliest mechanical calculators of which two are known to have survived to the present day. 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)".