Battering-ram

n.
  1. (Mil.) An engine used in ancient times to beat down the walls of besieged places.
  2. A blacksmith's hammer, suspended, and worked horizontally.

It was a large beam, with a head of iron, which was sometimes made to resemble the head of a ram. It was suspended by ropes to a beam supported by posts, and so balanced as to swing backward and forward, and was impelled by men against the wall.