Interior talus of the parapet, the slope from the top of the parapet to the banquette.
Talus of the top of the parapet, that slope which lessens the height of the parapet towards the berm, by which means the troops firing from the banquette can defend the covert way.
Exterior talus of the parapet, the slope of the parapet from the top to the berm.
Interior talus of the ditch, the slope from the top of the ditch to the bottom, within.
Tenailles are low works made in the ditch before the curtains; of which there are three sorts. The first are the faces of the bastion produced till they meet, but much lower; the second have faces, flanks, and a curtain; and the third have only faces and flanks. Their height is about 2 or 3 feet higher than the level ground of the ravelin. Their use is to defend the bottom of the ditch by a grazing fire, as likewise the level ground of the ravelin, and especially the ditch before the redoubt within the ravelin, which cannot be defended from any other quarter so well as from them.
Tenaillons are works made on each side of the ravelin, much like the lunettes; with this difference, that one of the faces in a tenaillon is in the direction of the ravelin; whereas that of the lunette is perpendicular to it.
Terre-pleine, in fortification, the horizontal superficies of the rampart, between the interior talus and the banquette. It is on the terre pleine that the garrison pass and repass; it is also the passage of the rounds.
Tower bastions are small towers made in the form of bastions; first invented by M. Vauban, and used in his second and third method; with rooms or cellars underneath, to place men and artillery in them. As these towers are almost a solid piece of masonry, they must be attended with great expence, though their resistance can be but little; for it has been found by experience, that the casemates are but of little use, because as soon as they have fired once or twice, the smoke will oblige the defenders to leave them, notwithstanding the smoke holes: hence it may be concluded, that the strength of these tower bastions does by no means answer their expences; and that, if small bastions were made instead of them, without casemates, they would be much better, and less expensive.
Traditore, in fortification, signifies the concealed or hidden guns in a fortification, behind the reverse of the orillon.
Traverse, in fortification, is a parapet made across the covert way, opposite to the saliant angles of the works, and near the places of arms, to prevent enfilades; they are 18 or 20 feet thick, and as high as the ridge of the glacis. There are also traverses made in the caponniers, but then they are called tambours.