MATHEMATICIAN, ASTRONOMER

Life
Father of the celebrated mathematician Hypatia, who worked with him, Theon lived during the reign of Theodosius the Great. He was the director of the "Museum" (University and Library) of Alexandria, and taught at the school where Euclid taught. Commentaries on his work survive in many texts (Suidas - Lexicon, 950 AD). He wrote a total of 13 books, of which only the first book of the "Commentary on the Treatise of Ptolemy" and a few other fragments are extant.


Work
His principal works are:

"Mathematics" (geometry).

"Arithmetic"

"On signs and divinations of birds"

"On the rising of Sirius" (the "Dog-star")

"On the flooding of the Nile"

"Commentary on the Treatise of Ptolemy, Convenient Rule"

"Commentary on Ptolemy's Almagest"

"Euclid's Elements": Published by Theon (~ 364 AD) and constantly in circulation world-wide until 1814 (1450 years!). Euclid's method was considered the best, because it was adapted to the needs of students.

"Equinoctial shift": Accepts the figure given by Ptolemy of 10 a century. It should be noted that in the view of some astronomers the shift is not progressive, but is confined to a variation of 8? of arc.