158 MILITARY SCIENCES. 



from the curtain and flanks, and parallel to these, the flanks of the tenaille 

 being cut off* by the lines of defence. Hereby arose a new curtain, D, and 

 two half bastions, E F, in the ditch, lower than the main work. Subse- 

 quently Vauban convinced himself that flanks were inadmissible, and gave 

 the tenaille merely two faces in the prolongation of the lines of defence, 

 intersecting at d, placing a very short curtain between them. To the 

 ravelin, G, Vauban gave greater extension, making the faces m q and mp = 

 f to I of ah, and drawing them from the points i and A, which are 30, 60, or 

 even 90 feet from the shoulder angles e and f. Afterwards he gave 

 the demilune flanks, as in p/. 48, figs. 2 and 3, which, however, proved 

 unserviceable. The gorge of the ravelin was determined, at first, by 

 the prolongation of the counterscarp, afterwards, however, as it was exposed 

 to the enemy's fire, cut oflT, as iicifig. 2, and in the interior a redoubt disposed 

 {figs. 2 and 3), which lay so high that its line of fire fell upon the ban- 

 quette of the ravelin. The ditch (fig. 1) received in front of the bastion 

 salients 90 to 96 feet breadth and was aligned upon the shoulder points, 

 whereby the gorge of the ravelin was determined in g. The ditch of the 

 demilune received at o ^^ and p n from 72 to 80 feet breadth, and ran 

 parallel to its faces. At r, when the ditch was dry, ran traverses for 

 defence. The covered way he improved by defending the long lines, I, I, 

 from the place of arms, H, by means of the traverses ss, also by enlarging 

 it and the glacis. 



Still more improved were the later systems of Vauban, viz. 6, that at 

 Landau (fig. 2) and 7, at Breisach (fig. 3). For Landau {fig. 2) the 

 construction upon the polygon side ab hy means of the perpendicular cd, 

 is the same as before ; but between the bastions A and B there lies no 

 curtain, the tenaille, C, is advanced to the point of intersection, d, and 

 lies on the same level with the bastion ; the faces, qp and q o, of the 

 ravelin with flanks, G, are aligned upon the much advanced points m and %, 

 and a redoubt, H, added ; the places-of-arms, K and L, made as large as 

 possible, the line, I, defended by several traverses and secured from enfilade, 

 and the glacis thrown very far forward. Elevated behind the front of attack 

 proper lie the bastion towers, F F, forming redoubts, and where the pro- 

 longation of the line of defence strikes these, is formed a second, retired 

 polygon side, fe, upon which, by means of the perpendiculars, ^ E, &c., a 

 new front of attack, ehk lif, with two half bastions, D, and a curtain, E, is 

 constructed. For the fortifications of Breisach {fig. 3), A are the bastions, 

 B the tenaille, ab is the polygon side, c d the perpendicular. The faces, 

 p, of the ravelin, F, which has a double redoubt, G, are aligned upon the 

 points/ and e, and the flanks tolerably long. The bastion towers, E E, are 

 made much smaller, whereby the second front of attack, ghiklmn, obtains 

 a greater extension, and the bastions, C C, as well as the curtain, D, receive 

 a better defence. H is a large re-entering, and I a salient place-of-arms. 

 The place K is contracted by the adjacent hornwork. L is a large glacis. 



We have given, in pi. 48, various details of Vauban's systems, most of 

 which are found usually in those of others, or may be applied to them. 

 Bastions may be either hollow or solid ; in the hollow bastion the interior 

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