Theon of Alexandria Theon of Alexandria Theon of Alexandria (; ; 335 – c. 405) was a Greek scholar and mathematician who lived in Alexandria, Egypt. He edited and arranged Euclid's "Elements" and wrote commentaries on works by Euclid and Ptolemy. His daughter Hypatia also won fame as a mathematician. Little is known about the life of Theon. He made predictions and observances of solar and lunar eclipses in 364 which show he was active at that time, and he is said to have lived during the reign of Theodosius I (379–395). The biographical tradition of the tenth century Byzantine "Suda" defines Theon
The Crown of Ptolemy The Crown of Ptolemy The Crown of Ptolemy is the third and last book in the "Percy Jackson and the Olympians" and "The Kane Chronicles" crossover series. It was released in the back of the paperback version of "The House of Hades" on March 31, 2015, and later as an ebook and audiobook. The ebook edition was released May 12, 2015. On January 15, 2015, Rick Riordan announced a third crossover story titled "The Crown of Ptolemy" on his Twitter account. His announcement included the fact that the short story would be first published in the paperback version of "The