On Architecture

Vitruvius Pollio

Vitruvius Pollio, creator; Morgan, M. H. (Morris Hicky), 1859-1910, translator

1. THERE is also another kind of tortoise, which has all the other details as described above except the rafters, but it has round it of boards, and eaves sloping down

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wards, 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 have all the other details as described above, but their fronts are constructed like the angels 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.

2. It does not seem to me out of place to set forth the principles on which Hegetor of Byzantium constructed a tortoise. The length of its base was sixty-three feet, the breadth forty-two. The corner posts, four in number, which were set upon this framework, were made of two timbers each, and were thirty-six feet high, a foot and a quarter thick, and a foot and a half broad. The base had eight wheels by means of which it was moved about. The height of these wheels was six and three quarters feet, their thickness three feet. Thus constructed of three pieces of wood, united by alternate opposite dovetails and bound together by cold-drawn iron plates, they revolved in the trees or amaxopodes.

3. Likewise, on the plane of the crossbeams above the base, were erected posts eighteen feet high, three quarters of a foot broad, two thirds of a foot thick, and a foot and three quarters apart; above these, framed beams, a foot broad and three quarters of a foot thick, held the whole structure together; above this the rafters were raised, with an elevation of twelve feet; a beam set above the rafters united their joinings. They also had bridgings fastened transversely, and a flooring laid on them protected the parts beneath.