The Encyclopedia Americana (1920)/Regiomontanus

REGIOMONTANUS, rē"jĭ-ŏ-mŏn-tā'nŭs, German astronomer, whose real name was Johann Müller, but who assumed that of Regiomontanus, in allusion to the place of his birth, Königsberg (Kings Mountain),

b. 6 June 1436; d. Rome, 6 July 1476. Having received a classical education at Leipzig, be placed himself under Purbachius (Georg von Purbach), the professor of mathematics at Vienna, and under him became one of the first astronomers of that age. With Purbachius he accompanied Cardinal Bessarion to Rome in 1461, where Beza gave him further instruction in Greek literature, and he now completed a new abridgment in Latin of the &lsquo;Almagest&rsquo; of Ptolemy (1496), correcting many errors in the former translation, made by George of Trebizond. In 1471 he built an observatory at Nuremberg and established a press, but after three years returned to Rome on the invitation of Sixtus IV, who employed him in the reformation of the calendar and rewarded his services by raising him to the bishopric of Ratisbon (1475). He died, according to some, of the plague, according to others by poison administered by the son of George of Trebizond out of revenge for his having exposed the errors of his father. Regiomontanus was the first in Germany to apply himself to the cultivation of the neglected science of algebra. He made great improvements in trigonometry, into which he introduced the use of tangents. His refutation of a supposed discovery of the quadrature of the circle and numerous writings on various subjects of natural philosophy display extensive learning and great acuteness. His astronomical observations from 1475 to 1506 (&lsquo;Ephemerides&rsquo;) are very accurate. Among his other works &lsquo;Kalendarium&rsquo; (about 1474), &lsquo;De Reformatione Kalendarii&rsquo; (1489); &lsquo;De Cometæ Magnitudine Longitudineque&rsquo; (1531); &lsquo;De Triangulis Omnimodis&rsquo; (1533); &lsquo;Tabulæ Directionum Prejectionumque in Nativitatibus multum utiles&rsquo; (1585). Consult Gunther, &lsquo;Johannes Müller&rsquo; (in the &lsquo;Allgemeine deutsche Biographie,&rsquo; Vol. XXII, 1855); also Ziegler, &lsquo;Regiomontanus als, geistiger Vorlä u fer des Columbus&rsquo; (1874).