162 MILITARY SCIENCES. 



high, 9 feet thick, and crenelled in two stories, save on the flanks, which 

 have embrasures and mortar casemates. Thirty-six feet from this wall is 

 the foot of the enceinte proper, m m, which is composed of bastions and 

 curtains, covers the enceinte, B, and has in front of it the wall, p q rf, 6 

 feet thick, and 24 feet high, crenelled in one story, which is united with the 

 above mentioned curtain by defensive casernes, k, having earthen parapets 

 above. In front of the curtain lies the tenaille, 1 1, whose faces are 360 feet 

 long. In the re-entering angle of this is a ditch caponniere, and at g are 

 passages in the flanks. Between the couvre-faces, I, is erected the cavalier, 

 L, and in front of this lies the ravelin, H, for sallies and to cover the couvre- 

 faces. The profile {pi. 48, fig. 32) along N M, shows the general enceinte 

 with the earthen rampart, B, the enceinte wall, C, the tenaille, e, and the 

 ditch caponniere, vw. Fig. 31 is a profile along O P, and shows the cava- 

 lier, L, the demi-lune, H, and the glacis, which slopes towards the works 

 (en contrepente) ; the profile, j^^. 30, is along the line, Q R, and shows the 

 bastion, h, the wall, q, the couvre-face, J, and the glacis. 



13. The system of Dufour (fig. 16) is based in general upon the bastion 

 system. The enceinte, ae g hfh, of bastions, A B, and curtains, C, is con- 

 structed by means of the polygon side, a b, and the perpendicular, c d, and 

 has in front of the tenaille, E, a caponniere, D, for communication with the 

 ravelin, whose faces are constructed as by Cormontaigne. In the salient 

 angle of the ravelin is found a cavalier, F, for protection against enfilade. 

 The ravelin has besides the cut-offs G and H, which serve for defence of 

 the ditch as well as for redoubts to the places-of-arms, I and K. The 

 ravelin faces consist of an earthen rampart, the flanks of crenelled walls, 

 the covered-way of the ravelin has four traverses. 



14. The system of the engineer Chasseloup (fig. 14) has chiefly in view 

 the protection of the defend«rs at every moment again'st the effects of the 

 hostile fires, and contains much covered space. His polygon side has 1800 

 feet. The main enceinte, ahcddcha, is bastioned, and has its faces, ahc, 

 broken, that they may not be ricocheted. For the protection of the advanced 

 works there are, in the great bastions, casemated cavaliers, c. The branches 

 of the covered-way have such a direction, that by means of these several 

 direct fires are brought upon the capital, and in the places-of-arms of the 

 covered-way are established bomb-proof redoubts, A, covered with earth. 

 To reach the covered-way more conveniently, ramps, r, are placed at the 

 necessary points. The salient angle, D, of the ravelin, is the apex of an 

 equilateral triangle, the ground lines of which are determined by two 

 points, on the bastion faces, 291 feet distant from the shoulder angles. The 

 ravelin faces, made up of coupures (cut-offs), as well as the faces of the 

 redoubt, E, run parallel to the lines of this triangle. The redoubt, E, is a 

 casemated lunette, covered with an earthen parapet, of one story, save in 

 the gorge, where it has two, and separated from the enceinte by the glacis, 

 W. The main work in Chasseloup's system is the work F, which possesses 

 great capacities for defence. The faces are covered by the glacis, and the 

 flanks by the caponnieres, P ; it is unassailable from a distance, and first 

 becomes effective when the enemy has arrived upon the glacis, W. Chas- 



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