Johannes Praetorius (mathematician)

Johannes Praetorius, also known as Johann Richter (1537 to 1616), was a German mathematician and astronomer, born in Joachimsthal in Bohemia. He studied at the University of Wittenberg from 1557, lived in Nuremberg from 1562 to 1569, and in 1571 became professor of mathematics, which then included astronomy, at Wittenberg, where he met Valentin Otho and Georg Joachim Rheticus. He died in Altdorf near Nuremberg at about the age of 79. His astronomical and mathematical instruments are kept at the Germanisches Nationalmuseum in Nuremberg. He taught the Copernican theory of astronomy at first as a means of removing the equant from the account of Ptolemy, and later moved toward a proto-Tychonic system. His works include a narrative on the comets seen in 1578, De cometis, and a 1598 problem on constructing a quadrilateral from four given straight lines so that it lies in a circle.