was a German watchmaker and inventor of calculating machines. Schuster, the son of a farmer, went to Philipp Matthäus Hahn's watchmaking apprenticeship for two and a half years and was also familiar with the construction of calculating machines at Hahn.

was a German professor of Hebrew and astronomy who became famous in the second part of the 20th century after Franz Hammer, a biographer (along with Max Caspar) of Johannes Kepler, claimed that the drawings of a calculating clock, predating the public release of Pascal's calculator by twenty years, had been discovered in two unknown letters written by Schickard to Johannes Kepler in 1623 and 1624.