REGIOMONTANUS, the name adopted by an early German mathematician, called Johann probably because he was a native of Khnigsbcrg (of which Regiomontanns seems intended as a Latin equivalent), where lie was born June 6, 1436. Which Konigs berg, however, is to be understood is a disputed point among his biographers, Delambre and others favor the one in Franconia. Regiomontanus was sent by his parents to Leipsic at the age of 12, and there made such rapid and extraordinary prog ress in mathematical studies that by the time he was 16 lie could find nobody, it is said, in the Saxon university competent to give him further instructions. Ile therefore removed to Vienna,where, in 1461, he became professor of astronomy, but was permitted to reside in Italy for some time, in order to study Greek, with the view of making him self acquainted with the writings of the Alexandrian geometricians and astronomers. He appears while here to have gone through a great amount of laborious work in the collec tion, collation, and copying of Greek MSS., in studying the language (under the best masters, such as Theodore Gaza), making astronomical observations, lecturing to the students of Padua on the Arabian philosopher Alfragan, and composing his celebrated work, De Triangalis Rank et Splicerkis (first published at Nuremberg, 57 years after his death), which, according to Delambre, gives a very complete account of what was then knowli of plane and spherical trigonometry. In 1‘64 Regiomontanus returned to Vienna, where lie remained for some years in the of his duties as professor, but after ward removed to Buda, in Hungary, on the invitation of Mathias Corvinus. In 1471 lie
went to Nuremberg, where he lived in close intimacy with a wealthy and enlightened citizen, named Bernhard Walther,who furnished him, among other things,with means to start a book-printing establishment, and to construct various astronomical instruments. by which they were enabled to demonstrate the inaccuracies of the "Alphonsine tables. Their united labors are to be found in the Observationes 30 Annorum a J. Regkmontano et B. Walther° (Nuremberg, 1544). Regiomontanus now devoted himself vigorously to the composition of scientific works, among others. his Kakndarium Novum (ante 147•), which is thought to have been the first almanac that ever appeared in Europe. This last work excited great attention among the learned and powerful of the time, and the first edition was rapidly sold off. The king of Hungary presented Regiomontanus with a gift of 800 or 1200 golden crowns. Pope Sixtus IV. now sought his assistance in his medi tated reformation of the calendar, and to secure his services conferred on him the dignity of archbishop of Ratisbon. He now left Nuremberg, and proceeded again to Rome, where, however, he died, July 6, 1476, at the early age of 41. Regiomontanus's prema tore death was a serious loss to the science of mathematics. He is pronounced by competent authorities the most learned astronomer of his age; and his sagacity and ardor were such as to promise important acquisitions to our knowledge of celestial physics. A list of his numerous writings is given by Delambre in the Biographic Universelle.