15There is another species of tortoise, which is just the same as that above described, except in respect of the braces. This has a parapet and battlements of boarding, and above, an inclined pent-house round it, tied in at top with planks and hides firmly fastened. Over these is a layer of clay with hair, of such thickness as to prevent the machine taking fire. These machines may be made with eight wheels, if need be, and if the nature of the place require it. The tortoises made for undermining, called by the Greeks ὄρυγες, are similar to those already described; but their fronts are formed on a triangular plan, so that the weapons from the wall may not fall direct on the faces, but gliding off from them, the excavators within may be secure from danger.
2It does not appear to me foreign to our purpose to explain the proportions and constructions of the tortoise made by Agetor the Byzantine. Its base was sixty feet long, its width eighteen. The upright pieces which rose above the framing, were four in number; they were in two lengths, joined, each thirty-six feet high, one foot and one palm in thickness, and in width one foot and a half. The base had eight wheels, on which it was moved; their height was six feet and three quarters, their thickness three feet, composed of three pieces of wood dove-tailed together, and tied with plates of cold wrought iron.
3These turned on naves, or hamaxopodes, as they are called. Above the surface of the cross pieces which were on the base, upright posts were erected, eighteen feet and a quarter high, three quarters wide, and three-twelfths thick, and one and three quarters apart. Above them were beams all round, which tied the machine together, they were one foot and a quarter wide, and three quarters thick. Over these the braces were placed, and were twelve feet high. Above the braces was a beam which united the framing. They had also side pieces fixed transversely, on which a floor, running round them, covered the parts below.
4There was also a middle floor above the small beams, where the scorpions and catapultæ were placed. Two upright pieces were also raised, joined together, thirty-five feet long, a foot and a half thick, and two feet wide, united at their heads, dove-tailed into a cross beam, and by another in the middle, morticed between two shafts and tied with iron hooping, above which were alternate beams between the uprights and the cross piece, firmly held in by the cheeks and angle pieces. Into the framing were fixed two round and smooth axles, to which were fastened the ropes that held the ram.
5Over the heads of those who worked the ram was a pent-house, formed after the manner of a turret, where two soldiers could stand secure from danger, and give directions for annoying the enemy. The ram was one hundred and six feet long, a foot and a palm wide at the butt, a foot thick, tapering towards the head to a foot in width, and five-eighths in thickness.
6It was furnished with a hard iron beak like those fixed on galleys, from which went out four iron prongs about fifteen feet long, to fix it to the beam. Moreover, distributed between the foot and the head of the beam, four stout ropes were stretched eight inches thick, made fast like those which retain the mast of a ship between the poop and the prow. To these were slung others diagonally, which suspended the ram at the distance of a palm and a foot from each other. The whole of the ram was covered with raw hides. At the further end of the ropes, towards the head, were four iron chains, also covered with raw hides,
7and it had a projection from each floor, framed with much skill, which was kept in its place by means of large stretched ropes, the roughness of which preventing the feet from slipping, made it easy to get thence on to the wall. The machine could be moved in six directions, straight forward, to the right and left, and from its extent it could be used on the ascending and descending slope of a hill. It could, moreover, be so raised as to throw down a wall one hundred feet in height: so, also, when moved to the right and left, it reached not less than one hundred feet. It was worked by one hundred men, and its weight was four thousand talents, or four hundred and eighty thousand pounds.