CLA!VIUS, CHRISTOPHER, of Bamberg, entered into the order of Jesuits, and died at Rome February 5, 1612, aged seventy-five. He was selected by Gregory XIII. to superintend the reformation of the Calendar, in which capacity he had to endure and reply to the attacks of Moestlinus, Joseph Scaliger, Vieta, and others of less note. As a mathematical writer, Clavius is distinguished by the number of his works, the frequency with which they were reprinted, his rigid adherence to the geometry of the ancients, and the general soundness of his views. According to Riccioli ('Chronicon, Nov. Almag.'), the most learned Germans resorted to Rome, that they might converse with Clavius, and several were accustomed to say that they would rather be attacked by him than praised by others. As Clavius did not possess any great original talent, his works are now of little con sequence, except to the mathematical historian. The following is the list of those which have been mentioned by succeeding writers :— 1, In 'Sphmrarn Jobannis de Sacro-bosco Commentarius,' Rome, 1570, reprinted more than a dozen times : the last edition we can find is that at Leyden, 1618. 2, ' The Works of Euclid,' with a commentary; Rome, 1574; Cologne, 1591 ; Frankfurt, 1607, &c. 3, 'Epitome Arithmetical Practieto,' Rome, 1583; Cologne, 1637, &c. 4, 'Edition
of the Spherics of 1 hecdosius, with a Table of Sines, Tangents, &c.,' Rome, 1586. 5, A work on Gnomonics, Rome, 1587; several times reprinted. 6, ' Defence of the Calendar against 3Ioestlinus,' Rome, 1588. 7, 'Fabrics et Uens, fic , a work on Horology, Rome, 1586; Constructio, &c.,' a second work, Louvain, 1595; Horol. Nov. Descr., &T.,' a third, Rome, 1599. 8, ' On the Astrolabe,' Rome, 1593, &c. 9, Refutation of J. Scaliger on the Calendar,' Rome, 1595; Mayence, 1609. 10, 'Romani Calendarii a Greg. XIII. Restituti Explicatio,' Rome, 1603. This is to us the most important of the works of Clavius : it contains the description of the reasons and methods employed in the alteration of the calendar, with the answer to Vieta and others. 11, 'Elements of Algebra,' Rome, 1604. 12, 'Geometria Practica; Rome, 1604. 13, Refutation of George of Wirtetuberg on the Calendar,' Rome, 1610. We have taken the earliest editions which we could find in any of the authors cited at the end.
A complete edition of the works of Clavius was published at Mayence in 1612. The account of the Calendar is in the fifth and last volume.
(Riccioli; Weidler ; Blaocanns ; Lipenius ; Bouillaud, Cat. Bibl. Mean.; Lalande ; Delambre.)