The date of the conquest of Antioch by the Arabs is of some importance. By comparing the years of the world in the chronography of Theophanes with the years of the Hegira in the history of Elmacin, we shall determine, that it was taken between January 23d and September 1st of the year of Christ 638 (Pagi, Critica, in Baron. Annal. tom. ii. p. 812, 813). Al Wakidi (Ockley, vol. i. p. 314) assigns that event to Tuesday, August 21st, an inconsistent date; since Easter fell that year on April 5th, the 21st of August must have been a Friday (see the Tables of the Art de Verifier les Dates ).