On Architecture

Vitruvius Pollio

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

3. Let the rafters themselves be held together by bridgings, and covered with boards, preferably of holm oak, or, this failing, of any other material which has the greatest strength, except pine or alder. For these woods are weak and easily catch fire. Over the boardings let there be placed wattles very closely woven of thin twigs as fresh as possible. Let the entire machine be covered with rawhide sewed together double and stuffed with seaweed or straw soaked in vinegar. In this way the blows of ballistae and the force of fires will be repelled by them.

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.