in 



FORTIFICATION. 



FORTIFICATION. 



171 



improvements in the details of the work*. He made the flank* exactly 

 perpendicular to thr prolonged faces of the collateral bastion*, for the 

 sake of a more complete flanking defence. He made the tern-plains of 

 the ravelins merely wide enough to contain the artillery of the 

 defender*; in order to increase the capacity of the redoubt in the 

 ravelin, and to deprive the enemy of the space necessary for a battery 

 on the ravelin, by which he might breach that redoubt. He also gave 

 Urge caMmitad flanks to the latter work, in order that a powerful fire 

 might be directed from them against the enemy, if he should attempt 

 to mount the breach in the face of either bastion before he had got 

 possession of the redoubt* as well as of the ravelins themselves. A 



further improvement was made by this engineer In adding to each of 

 the re-entering places of arms a spacious redoubt, which would render 

 the defence of that place more obstinate, and cover the passage 

 between the tenaille and the flank of the bastion. The following are 

 the commands of the principal works above the country. 



aalient of button . . . . 26 J feet dMnuinf 1 foot to flank of da. 

 8Uent of redoubt of ravelin . 24 



Salient of ravelin . . 11 extremity of face. 



Redoubt In Re-entering place of arm* 14 



Tcnaille 8 



Covered-way 9 



J'lan of a Front of Fortification according to the Method of Cormontalngne. 



80 yards to an inch. 



*. Solid Bastion ; , Hollow ditto ; x, Retrenchment ; r, Tenalllc ; o, Caponniere ; a a, Karelin ; v, Uedoubt in ditto ; L L, Re-entering placet of Arms ; 

 w w, Redoubts in ditto ; a x, Corered-wty ; ( f, Traverse* ; s s, UlacU ; z, Barbette battery. 



Cormontaingne's system, to which the name of French modern 

 system was for some time applied, liaa at various times been modified 

 in many of its details, especially by the French engineers at their 

 schools of application (formerly at Mezieres, and now at Mctz), and at 

 the present time the U-nn of Modem System is applied to one which 

 may be considered as the most perfect Bastioued trace, and which is 

 taught in the French engineer schools as the normal bastion trace. 

 The proportions given by Cormontaingne to the enceinte arc retained 

 with the exception that the flank is increased by directing the escarp 

 of the face* of the bastion to the angle of the flank of the magistral 

 line instead of to the interior crest. The saliency of the ravelin is 

 however still farther increased, and it is in this that the principal 

 modification of the modern system lies, by directing its faces on the 

 faces of the bastion points 86 yards from the shoulders, and giving the 

 salient or flanked angle the greatest saliency possible, allowing it in fact 

 only an owning of 60, which is the least admissible. The ravelin being 

 thus enlarged allows of a larger redoubt, though the terreplein of the 

 ravelin, which Cormontaingne only considered a species of counterguard, 

 is also increased. A permanent coupure is made across each face of 

 the ravelin at the point where a perpendicular from the extremity of 

 the magistral line of the nearest face of the redoubt of the covered way 

 cuts it in order that the besieger may not by sapping along the face of 

 the ravelin, and thus be able to see into and drive the defenders out 

 of the redoubt. The greater saliency of the ravelin allows of four 

 traverses in the covered way instead of the three, according to 

 Cormontaingne's system. 



The modern system however has some important defects, among 

 which the principal are that the ravelin and its covered way present 



long lines easily enfiladed, and the faces of the bastion may be breached 

 by the besieger firing down the ditch of the ravelin from his breaching 

 battery on the crest of the glacis at ita salient, even more easily than 

 in Vuuban's first system. The flanks of the bastion also being brought 

 closer together, increase the undefended portion in front of the 

 curtain and tenoille. To remedy these defects, Colonel Dufour has 

 proposed certain modifications. Taking the outline of the enceinte 

 and of the ravelin, the same as those of the modern system, he raises 

 a large mound at the salient of the latter by laying off 45 yards along 

 each face, and raising it 44 feet above the plane of site or level of the 

 country. This by its elevation entirely screens the faces of the ravelin 

 from enfilade fire. Again the inner face and ditch of the redoubt of 

 the re-entering place of arms, instead of terminating on the counterscarp 

 of the ditch of the ravnlin, is continued across the ditch to the counter- 

 scarp of the ditch of the redoubt of the ravelin, perpendicular to it* 

 face at the shoulder angle, cutting off therefore the face of the ravelin 

 by making a coupure in it and preventing the besieger breaching the 

 bastion down its ditch. The flanks of the redoubt of the ravelin are 

 simply crenelled walls, in order not to give the besiegers any cover from 

 which to drive the defenders from the redoubt of the covered way and 

 the coupure of the ravelin, which are intended to be held till the last. 



Soon after the commencement of the revolution, Bousmard, a French 

 officer, who had entered the service of the king of Prussia, proposed to 

 curve the faces of the bastions on the plan, lu order to diminish or 

 prevent the effect of the ricochet, and to build casemates in the flanks 

 of the tenailli s for the purpose of more effectually defending the main 

 ditch. His traverses in the covered way are like little redans, each 

 being a little retrenchment having a separate communication with the 



