Christopher Clavius was born in a German region and must have had a German name before adopting the Latin 'Clavius'.
Christopher Clavius S. J. (1537 - 1612) was a German mathematician and astronomer. Renowned as a teacher and writer of textbooks, Clavius was particularly active in the reform of the Gregorian calendar. This is the title page of his collected works, Opera Mathematica, (1612), five volumes. The first volume contains his commentaries on Euclid and the “Spheric” of Theodosius. The second volume contains his works on algebra and geometry and the third volume contains a commentary on Sarobosco’s “Sphaera” An account of the construction of sundials is given in the fourth volume, while the last volume contains information on calendar reform.
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