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Clavius [Klau], Christoph

1. Dates
Born: Bamberg, c. 25 March 1538
Died: Rome, 6 February 1612
Dateinfo: Dates Certain
Lifespan: 74
2. Father
Occupation: No Information
No information on financial status.
3. Nationality
Birth: Germany
Career: Italy
Death: Italy
4. Education
Schooling: Coimbra, Collegio Romano, D.D.
Studied for a time at the University of Coimbra (Portugal). One statement indicates that he was there in 1559.
From ca. 1563, studied theology at the Collegio Romano in Rome.
From subsequent career I assume a B.A., and as a Jesuit who had taken all four vows, he had to have had a degree in theology.
5. Religion
Affiliation: Catholic, a Jesuit.
He entered the Jesuit order in 1555.
6. Scientific Disciplines
Primary: Mathematics, Astronomy
1574: Elements of Euclid, which contained thoughts of his own. Also an Algebra in 1608.
Clavius was a supporter of the Ptolemaic system. He was the major technical advisor on the calendar reform.
7. Means of Support
Primary: Ecc 1555, Entered Jesuit Order.
Secondary: 1565-1612, For All But Two Years On The Faculty Of The Collegio Romano either as Professor of Mathematics or Scriptor. I will list this as an ecclesiastical position, in keeping with my policy on Jesuits in Jesuit institutions.
1595-6, stationed in Naples.
In 1597 he was in Spain, apparently at the behest of the king, but nothing else is known about this.
8. Patronage
Types: Ecclesiastical Official, Court, Aristocracy
An important force in the calendar reform of 1577-1582, Clavius was given the assignment by Popes Gregory XIII and Clement VIII of commenting on the new calendar and defending it against the attacks of the protestants, which he did in Novi calendarii romani apologia (Rome, 1595).
Philips mentions his dedications, and the letters of acknowledgment he received: Rudolf II, Ferdinand II the Archduke of Austria, the Duke of Urbino, various ecclesiastical officials.
See the reference to the King of Spain above.
9. Technological Involvement
Type: Instruments
He improved upon, by simplifying, a precursor to the vernier that made it possible to measure fractions of angles. He also made a calculating device similar to Galileo's compass.
He also developed a form of the quadrant useful for surveying.
He wrote on sundials and developed new forms of them.
10. Scientific Societies
Memberships: None
Corresponded with Galileo (who was also a personal friend), Tycho, Ricci, Magini, Ursus, von Roomen, Ghetaldi, Welser, and del Monte, among others (see Philips for catalogue).
His correspondence holds enquiries he received from about 110 diff men, mostly in Italy but also from the rest of Europe, consulting him on scientific questions. However, these enquiries did not lead to sustained discourse.
  1. Allgemeine deutsche Biographie.
  2. E.C. Philips, "The Correspondence of Father Christopher Clavius, S.I.," Archivum historicum Societas Iesu, 8 (1939), 193-222.
  3. Edmond R. Kiely, Surveying Instruments, (New York, 1947), p. 176, E. Knobloch, "Sur la vie et oeuvre de Christopher Clavius," Revue d'histoire des sciences, 41 (1988), 331-56.
  4. Charles Naux, "Le pere Christophore Clavius (1537-1612). Sa vie et son oeuvre," Revue des questions scientifiques, 154 (1983), 55-67, 181-93, 325-47.
Not Available and Not Consulted
  1. O. Meyer, "Christoph Clavius Bambergensis," Fraenkisches Land, 9 (1962), 1-8. There must be something wrong with this reference from DSB; such a journal cannot be found.
  2. Ugo Baldini, "Christoph Clavius and the Scientific Scene in Rome," Gregorian Reform of tahe Calendar. Proceedings of the Vatican Conference to Commemorate its 400th Anniversay 1582- 1982, G.V. Coyne, M.A. Hoskin, and O. Pedersen, eds. (Vatican City, 1983), pp. 137-69.
Compiled by:
Richard S. Westfall
Department of History and Philosophy of Science
Indiana University

Note: the creators of the Galileo Project and this catalogue cannot answer email on geneological questions.

1995 Al Van Helden
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