‹‹‹ Vitr. 10.14.3 | Table of Contents | Vitr. 10.15.2 ›››
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.
15There is also another kind of tortoise, which has all the other details as described above except the rafters, but it has round it a parapet and battlements of boards, and eaves sloping downwards, and is covered with boards and hides firmly fastened in place. Above this let clay kneaded with hair be spread to such a thickness that fire cannot injure the machine. These machines can, if need be, have eight wheels, should it be necessary to modify them with reference to the nature of the ground. Tortoises, however, which are intended for excavating, termed in Greek ὁρυκτἱδες, have all the other details as described above, but their fronts are constructed like the angles of triangles, in order that when missiles are shot against them from a wall, they may receive the blows not squarely in front, but glancing from the sides, and those excavating within may be protected without danger.