Theodosius

, called Tripolites, or of Tripoli, was a celebrated mathematician, who flourished, as Saxius seems inclined to think, in the first century. He is mentioned by Suidas, as probably the same with Theodosius, the philosopher of Bythinia, who, Strabo says, excelled in mathematics. He appears to have cultivated chiefly that part of geometry which relates to the doctrine of the sphere, on which he wrote three books containing fifty-nine propositions, all demonstrated in the pure geometrical manner of the ancients, and of which Ptolomy as well as all succeeding writers made great use. These three books were translated by the Arabians out of the Greek into their own language, and from the Arabic the work was again translated into Latin, and printed at Venice. But the Arabic rersion being very defective, a more complete edition was published in Greek and Latin at Paris, in 1558, by John Pena (See Pena) professor of astronomy. Theodosius’s works were also commented upon by others, and lastly by De Chales, in his “Cursus Mathematicus.” But that | edition of Theodosius’ s spherics which is now most in use, was translated and published by our countryman the learned Dr. Barrow, in 1675, illustrated and demonstrated in anew and concise method. By this author’s’ account, Theodosius appears not only to he a great master in this more difficult part of geometry, but the first considerable author of antiquity who has written on thai subject. Theodosius also wrote concerning the celestial houses; and of dnys and nights; copies of which, in Greek, are in the king’s library at Paris, and of which there was a Latin edition, published by Peter Dasypody in 1572. ¹