Continued lines are simple parapets, either connecting fortified posts, or covering the front or flank of an army. Redans joined by curtains are those most easily constructed; but as the ditches can only be defended by an oblique fire, the curtains are occasionally so broken as to form nearly right angles with the faces of the redan; they then become lines of tenailles.
Lines en Cremailliere have long faces with perpendicular flanks. Lines with intervals are often as effective as continued lines. They consist of detached works, in two lines, within musketry fire of each other. The re-entering angle should as nearly as practicable be a right angle. The celebrated lines of Torres Vedras, before adverted to, consisted of 150 detached forts.
Tete-du-pont, is a work constructed to cover the approaches to a bridge, and will be found described under BRIDGE-HEAD.
A tenaille is the reverse of a redan, and consists of two faces forming a re-entering angle: it can only be used in connection with some other work.
A Pelle is a breastwork of two faces, forming a salient angle, constructed on the exterior of a glacis, usually at its foot, in order to defend the ground before a bastion or ravelin.
Having now explained the principal forms which elemental works of F. are made to assume, we proceed to describe—very briefly, of course—the systems into which these have been incorporated for the defense of fortresses, towns, and other permanent pur poses. It will merely be necessary to state, in addition to what has been already written, that a rampart is a raised structure of earth or stone, above the mean level of the country, on which the parapets, etc., can be thrown up, and which affords to the town or space protected the extra cover of its height, while it elevates the inner works sufficiently to enable them to command and fire over those situated exteriorly to them selves. It need scarcely be said that a line which can be made of earth may equally be constructed of any other material which circumstances may render desirable, the maximum resistance and minimum liability to splinter being the qualities to be chiefly considered.