Publisher's Synopsis
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1884 edition. Excerpt: ... c, of the curtain and the extremity, t, of the ravelin face. The condition is imposed that the inner end of the magistral of the redoubt shall lie on this line prolonged. A point, a, is taken within the ravelin, on the perpendicular of the front, and five yards from the salient, r, of the ravelin. Through a point, as b, assumed upon the ravelin counterscarp, and the point a draw a right line. Draw through the point b a right line, making an angle of 60 with the line ab o. Within the angle m b o, a line is drawn parallel to and 4.33 yards from the line m b; also, one parallel to b o and 2.0 yards distant. If these two lines intersect on the line c t produced, the point of intersection will be the extremity, and the line m b' will be the projection of the magistral of the face of the redoubt next to the ravelin. If the intersection is not upon the line c ti other points, as k, etc., should be assumed on the counterscarp of the ravelin, and similar constructions made until the condition imposed is satisfied. Knowing one extremity, it will be necessary to determine the other extremity, m', to have the projection complete. Having found this extremity, m', the magistral of the other face is projected in a line passing through m' and a point of the interior crest of the bastion face 13.0 yards from the pancoupe. This direction is given to this face so as to allow its ditch to be swept by the fire of the bastion. To determine m, it will be necessary to consider first the length of the interior crest of the face, and determine the position of its salient, s. The besiegers upon reaching the covered way around the salient of the ravelin would proceed to establish breaching batteries on its glacis to fire upon the ravelin, and counterbatteries to...
