EUTO'CIUS, a Greek mathematician of Ascalon in Palestine, who flourished about 550. He was pupil of Isidorus, the architect who designed and chiefly built the celebrated church (now the mosque) of St. Sophia at Constantinople ; and he became ultimately one of the most distinguished geometricians of his time.
It was the general custom of mathematical and philosophical authors, during the decline of learning, to give their views and their discoveries, where they made any, in the form of commentaries on some earlier writer. Eutocius, like Proclus and others, delivered his views in this way ; and, like them, he furnishes some valuable contri butions to the history of mathematical science amongst the Greeks. The commentaries of Eutocius on the works of Archimedes and Apollonius are the only works by which he is known to modern readers. His commentaries on Apollonius were published in Halley's Oxford edition of the works of that author, 1710; and those on Archimedes in various editions, from that of Basel, 1544, to that of Oxford, 1792.
Of the commentaries of Eutocius, those on the treatise of Archimedes On the Sphere and Cylinder' are most valued; and chiefly for his account of the various modes of solving the Delian problem of the Duplication of the Cube. All of them however, though of less value both as to historical and geometrical matter, are still interesting to every one who takes a pleasure in investigating the history of pure science. The commentary on the Measurement of the Circle,' by Archimedes, was translated into German, together with the text of Archimedes to which it refers, by J. Gutenacker, 1Viirzburg, 1825 and 1828, 8vo.