Johannes Praetorius

Johannes Praetorius, also called Johann Richter, was a German mathematician and astronomer, born in Jáchymov in Bohemia in 1537 and dead on 27 October 1616 at Altdorf near Nuremberg at about seventy-nine. He studied at the University of Wittenberg from 1557, lived in Nuremberg from 1562 to 1569, and in 1571 became professor of mathematics, meaning astronomy, at Wittenberg, where he met Valentinus Otho and Joachim Rheticus. His astronomical and mathematical instruments are kept at the Germanisches Nationalmuseum in Nuremberg. He taught Copernicus's theory at first as a means of removing the equant from Ptolemy's account and later moved to a proto-Tychonic system. His works include a 1578 narrative on comets and a 1598 problem on making a quadrilateral inscribed in a circle from four given straight lines.