Philipp Matthäus Hahn (1739 - 1790) was a German priest and inventor. In 1773 he designed the first functional mechanical calculator. The son of a Lutheran pastor, he attended the Latin school of Esslingen am Neckar. When he was only thirteen, his mother died. Influenced by his very pious family, he decided to continue his studies at the Würtemberg convent but failed the entrance examination. Instead he attended a school for preparing the lower clergy in Nürtingen, where he developed his skills as a self-taught technician by creating solar clocks. At the same time as he took further studies at Tübingen, he began the development of new scientific instruments, such as the microscope, the telescope and the calculator. Following this, he began a career as a schoolteacher at Lorch before obtaining the position of Vicar at Breitenholz in 1761 and becoming pastor of Onstmettingen (Albstadt) three years later. After the death of his first wife in 1774, he married the daughter of pastor Johann Friedrich Flattlich and became pastor of Echterdingen in 1781.
During his time as a pastor, he designed his first needle balance and first planetary clock in collaboration with Philipp Gottfried Schaudts. He also made others, including the remarkable Nuremberg model, a clock that included a calendar that ran until the prophesied day of the Apocalypse, as well as an orrery machine that was geosynchronous and heliosynchronous. However, these items were not discovered until after Hahn's death. Invited by his sponsor, Carl Eugen Herzogs, he went to Kornwestheim, where he developed a watchmaking workshop, in which he employed many of his friends. In this period, because of his scientific achievements, he acquired the very honorable title of "God's watchmaker." In 1989, a museum was dedicated to him in Onstmettigen.