High Quality Content by WIKIPEDIA articles! 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 Dr. Franz Hammer, a biographer 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.