Jesuit mathematician and astronomer, and one of the principal collaborators in the Gregorian calendar reform (1577–82); b. Bamberg, 1537?; d. Rome, Feb. 6, 1612. He entered the Jesuit Order in 1555, studied at Coimbra under P. Nunes, and taught mathematics at the Collegio Romano from 1565.
In addition to his defense and explanation of the calendar, Novi calendarii romani apologia … (Rome 1595), Clavius wrote on all branches of mathematics. He is noted for his pedagogical skill, rather than as a creative mathematician. His Euclides Elementorum … (1574 and many later editions), with its detailed commentaries and supplementary material, became the standard text in the schools. The first six books were translated into Chinese under the direction of his student Matteo ricci. His Opera Mathematica (5 v. Mainz 1611–12) contains, among other works, his practical arithmetic (first pub.1583), practical geometry (1604), algebra (1608), and commentaries on the sphere of john de sacrobosco (1570) and Theodosius (1586).
Clavius corresponded with the leading scholars of the day, and his letters confirming Galileo's discoveries with the telescope were very influential.
Bibliography: c. sommervogel, Bibliotèque de la Compagnie de Jésus, 11 v. (Brussels-Paris 1890–1932) 2:1212–24. e. lamalle, Neue deutsche Biographie (Berlin 1953–) 3:279. j. e. hofmann, Geschichte der Mathematik v. 1 (1953). e. c. phillips, "The Correspondence of Father Christopher Clavius, S.J.," Archivum historicum Societatis Jesu 8 (1939) 193–222. g. v. coyne, m. a koskin, and o. pedersen, eds., Gregorian Reform of the Calendar: Proceedings of the Vatican Conference to Commemorate Its 400th Anniversary 1582–1982 (Vatican City 1983).
[j. b. easton]