MÜLLER, JOHANN, surnamed, from the Latinized name of his native place, Regiomontanus, the greatest mathematician of the fifteenth century, was born in 1436 at Königsberg, but whether at the town of that name in Franconia or in Prussia is disputed. At the age of twelve he was sent for his education to Leipzig, and at the end of four years he rivalled his teachers in arithmetic, geometry, and astronomy. His studies were next prosecuted under Peuerbach, the astronomical professor in Vienna. Here his talents and acquirements recommended him to the notice of his teacher and the celebrated Cardinal Bessarion. On the death of the former in 1461, he was appointed to the vacant chair, and was encharged with the completion of a new translation of Ptolemy's Almagest which had been begun by the deceased professor. But before entering on these arduous tasks he repaired to Italy, to acquire a thorough knowledge of the Greek language. While study-
ing philology at Rome, Ferrara, and Padua, he was also engaged in writing his De Triangulis, a treatise which proved an important acquisition to trigonometrical science. Shortly after 1464 he returned to Venice. Before, however, his stay in that city had been prolonged over many years, an invitation from the King of Hungary drew him to Buda. There his time was employed in constructing his Tabula Directionum Profectionumque, &c., a work which was afterwards printed in 1475, and which contained the first table of tangents ever published in Europe. A great stimulus was given to his studies by his removal to Nuremberg in 1471. By a wealthy inhabitant of that town named Bernard Walter he was supplied with astronomical instruments and with a printing-press. He was thus enabled to carry on that important series of observations which were continued after his death by Walter, and which were long afterwards, in 1544, published under the title of Observationes Triginta Annorum, 4to, Nuremberg. Another important work which he produced about this time was the Kalendarium Norum for the three years 1475, 1494, and 1513. It passed into Hungary, Italy, France, and England, was speedily sold off, and increased the fame of its author. In 1475 he was appointed archbishop of Ratisbon, and was invited to Rome by Pope Sixtus IV. He had only lived a year in that city when he was cut off, at the age of forty. His remains were interred with great honour in the Pantheon. Gassendi appended a Life of Müller to his Life of Tycho Brahe, 4to, Paris, 1654. (For an account of the services of Regiomontanus to the cause of science, see DISSERTATION IV., § i.)