The battering-ram, the tenebra of the Romans, used both on land and sea, was a heavy oak beam tapering towards the head, which was shod with iron with a point at the extremity. It was exactly the same in the middle ages as in Roman times. There is a Roman specimen in the Germanische Museum at Nuremberg, which is about a foot in diameter at the base, and about eleven feet in length. It is still shod with iron. Sometimes in the middle ages this machine was made available for the united energies of many men, by means of beams joined together and suspended in a sling or massive trestle, whereby its force could be enormously increased. It was sometimes impelled on rollers or wheels and rapidly run forward to batter a wall. An engine similar to this is figured at Nineveh. The besieged did their best to deaden its effect by means of woolsacks or bags of hair let down from the parapet. The “sow” or “cat,” the vinea of the Romans, is a shed on wheels, covered with raw hides, used as a cover for preparing the way for the use of movable towers and other engines. This machine is the ancient “pluteus.” The testudo (_testa_, a shell), the more modern “tortoise,” was also a movable shed like the cat, but it contained a battering-ram for attacking a rampart. The berefreid, beffroi or belfrey, is a movable tower used for scaling walls. It was constructed in several storeys, with intercommunications by means of ladders or staircases, and high enough to overtop the parapet of the fortress assailed; provided with a drawbridge for an assault in force, and was often rolled on wheels to the point of attack. A machine of this kind, built by order of Simon de Montfort, was used at the siege of Toulouse, and, according to the ballad of the “Albigéois,” was adapted to contain five hundred men. The last of these engines was constructed as late as the reign of Charles I., and it was taken by the parliamentary forces. Mantlets stuck in the ground provided shelter for the archers, and other combatants, beneath the walls, against “Greek fire,” showers of rocks, and other missiles, hurled from the battlements by the defenders.