Petrus Apianus (1495–1552) was born in Saxony as Peter Bienewitz. He studied at the University of Leipzig from 1516 to 1519, where he took a Latinised version of his German name, Petrus Apianus. In 1519 he moved to Vienna, where he was part of the second Vienna school of cartography, including Georgius Tannstetter and Johannes Cuspinianus. He then moved again to Landshut, where he produced the ‘Cosmographicus liber’ in 1524, an extremely popular work on astronomy and navigation which underwent thirty reprints. Based on Ptolemy, it contains paper instruments called volvelles, which Apianus would use so effectively in his work that they are sometimes known as Apian wheels.