Roman soldiers using two forms of battering ram against the walls of a fortress. B is hung on a chain hanging from a frame, so enabling the men to concentrate their strength on thrusting the battering ram forward rather than the simpler form carried on their shoulders. C is mounted on a siege tower. From Poliorceticon sive de machinis tormentis telis by Justus Lipsius (Joost Lips) (Antwerp, 1605). Engraving.