Johannes Werner

Johann Werner, usually called Johannes Werner, was a German mathematician born in Nuremberg on 14 February 1468, who died there in May 1522. He studied at Ingolstadt, was ordained a priest in Rome in 1493 and spent his later career as a parish priest in Nuremberg, devoting his spare time to astronomy, mathematics and geography. He made astrolabes, sundials and cross-staffs, followed Regiomontanus in astronomy, and in 1514 published a translation of Ptolemy's Geography with his own commentary, in which he proposed finding longitude from the position of the Moon among the stars. In mathematics he worked on spherical trigonometry and conic sections, was the first to use the product-to-sum identity for sines as an aid to calculation, a device later used by Rheticus and Brahe until logarithms arrived, and gathered eleven ancient methods of duplicating the cube. Between 1513 and 1520 he kept the first regular weather observations in Germany, and many consider him a pioneer of weather forecasting.