The engineer's name was Priscus. His skill saved his life, and he was taken into the service of the conqueror. For the particular facts of the siege consult Dion Cassius (l. lxxv. [c. 10] p. 1251), and Herodian (1. iii. [c. 6] p. 95): for the theory of it, the fanciful chevalier de Folard may be looked into. Polybe, tom. i. p. 76.