Wilhelm Schickard

Wilhelmus Schickart (painted 1632)Wilhelm Schickard is holding a hand planetarium (or orrery) of his own invention. It was painted in 1632, 8 years after his last calculating clock drawing. Wilhelm Schickard (22 April 1592 – 24 October 1635) 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.

Hammer asserted that because these letters had been lost for three hundred years, Blaise Pascal had been called and celebrated as the inventor of the mechanical calculator in error during all this time.