FORTIFICATION. 



the foot of the glacis , at <J> 5 opposite to 

 the flanked angle of the bastion C, in the 

 horn-work M, carried through the cen- 

 tre all the way up to E, which is the cen- 

 tre of the polygon, should graze the crests 

 or inner summits of all the parapets 

 standing in that line : this is called the de- 

 filement of the ramparts. By such a con- 

 struction it must be obvious, that every 

 added work is a screen to, but is com- 

 manded by, that within it : thus, the bas- 

 tion C, in the crown-work M, is a screen 

 to the raveline N, and that again to the 

 curtain u v, while the intrenchments/yi 

 correspond in height with the flanks of 

 the horn-work, so as to be under the 

 command of the raveline, though they 

 command all that portion of M which is 

 in their front; and would continue to do 

 so, until the beseigers should construct 

 batteries in the gorges of the bastions b, 



C, 6, or elsewhere, and render // un- 

 tenable. 



The angle C, of bastion 4, is covered 

 by the counterguard 7, which not only 

 has that effect, but protects the adjacent 

 tenaillon R, and can plonge upon the ad- 

 joining flank of the crown-work M. As a 

 still further covering to the bastion 4, a 

 fleche 9.is added, parallel to the counter- 

 guard 7, at the foot of its glacis, serving 

 to render the attack more tedious and 

 difficult, by compelling the beseigers to 

 commence their approaches at a greater 

 distance, where they are more generally 

 subject to the fire from the bastions, &c. 

 of the crown-work. The fleche (/. e. 

 arrow-head,) should properly extend 

 equally each way, having both faces alike, 

 but that is not of any moment, and might 

 have a second glacis ; it is connected with 

 the counter-guard, or with the crown- 

 work, or with the tenaillon, by means of 

 a sortie, or winding passage, cut through 

 the glacis, or by a, caponnier, as in the 

 plate, intercepted with traverses, which 

 will be duly explained when treating of 

 the covert way. 



The raveline K is defended within by 

 the redoubt L, surrounded by a dry 

 ditch. This redoubt should not be too 

 high, because it would else serve to shel- 

 ter the enemy in case they should suc- 

 ceed in silencing the faces of C 6, and m 



D, of the corresponding bastions 4 and 5. 

 The small work S is a lunette, which must 

 be carried, or silenced, before the rave- 

 line can be breached in that part; and, 

 indeed before any lodgment can be made 

 opposite to the flanked angle D, of the 

 bastion o. The lunette must be lower 

 than the raveline, from which it properly 



derives its defilement, as will be here- 

 after explained. 



The tenaillon 11 is a very important 

 conjunctive to the raveline K ; it, in fact, 

 doubles its force on that side, and pro. 

 longs the battery of its other face ; it 

 flanks the counterguard, and its direct 

 fire is a great protection to the demi- 

 bastion b t on that side of the horn-work, 

 as well as to the whole face of its rave- 

 line a ; it commands the fleche ; and be- 

 ing itself commanded by the raveline K, 

 and by the face C 6, and the counter- 

 guard 7, cannot be occupied by an ene- 

 my while any of these three works re- 

 main in force. 



With respect to the construction of the 

 counterguard, lunette, and tenaillon, they 

 are not upon any exact scale in propor- 

 tion to the principal, as the raveline is, 

 but though not pei'fectly arbitrary, their 

 formations depend on some general rules, 

 which should invariably be had in view. 

 The counterguard is always placed on 

 the counterscarp, its front immediately 

 behind the glacis, and its rear, generally, 

 being a continuation of the revetement 

 of the counterscarp, so that the passage 

 lays along its terre-pleine, or battery. 

 This kind of work may be of any extent, 

 that is, it may proceed from raveline to 

 raveline without interruption ; or it may 

 break off where it enters a lunette, a te- 

 naillon, or a redoubt ; or it may be only 

 formed of two parallels equal in length 

 with the faces of the bastion. On account 

 of the number of men required for the 

 defence of extensive out-w r orks, counter- 

 guards are advantageously made hollow, 

 having casements covered with bomb- 

 proofs, their parapets being solid mason- 

 ry : their entrances, at each end, are se- 

 cured by barriers and drawbridges; and 

 their walls may, in places, be pierced 

 with loop-holes, through which musque- 

 try may be discharged against assail- 

 ants. 



Casemates are likewise made on each 

 side of the posterns, or arched passages 

 through the faces of ravelines ; there are 

 always drawbridges and barriers in such 

 situations, as also at the cuts through the 

 lunettes, &c, which lead through the co- 

 vert way to the esplanade, and are call- 

 ed sorties. The necessity for casemates 

 must, generally, depend on the quantity 

 and distance of out-works from the body 

 of the place : it should be a rule never to 

 place an out-work so that it could be cut 

 off, without receiving aid from some suf- 

 ficiently strong and contiguous part. 

 Wtr~ this neglected, the enemy would 



