 Philipp Matthäus Hahn

Philipp Matthäus Hahn (25 November 1739 in Scharnhausen, today part of Ostfildern – 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.