FORTIFICATION. 



beyond its ditch may be very numerous, 

 though not so varied as those placed be- 

 yond a crown-work. 



The object of beth these defences, ge- 

 nerally, is much the same ; when a small 

 diminishing" tract is to be covered, the 

 hom-worK is proper, but when a round, 

 or rather increasing, spot is to be enclos- 

 ed, the crown-work should be preferred. 

 The intrenciiments within a horn-work 

 are, however, the strongest, because they 

 oppose a larger front against a smaller 

 one; which 'is the reverse of what takes 

 place in the crown-work, where the in- 

 trenchments,/^ are narrower than the 

 front which can be opposed to them, be- 

 tween the flanked angles of the demi-bas- 

 tions b b. 



The explanation of fig. 2 next demands 

 our attention : it is the profile of the prin- 

 cipal, and of the proximate outwork. In 

 this, not only the defilement, but the de- 

 viations from the terre-pleine, or line of 

 the horizon, whether by superstructure 

 or by excavation, are shewn. 



A. represents the rampart of the prin- 

 cipal, or body of the places of which the 

 measurements may be in general terms, 

 taken at the following computation. The 

 height of the terre-pleine H, on which the 

 cannon are mounted, 20 feet ; the ban- 

 quette I, on which the soldiers stand to 

 fire their small arms, raised 3 feet above 

 H; the point X, which is the crest of the 

 parapet,being4^feet above the banquette 

 I, and 7^ above the terre-pleine H. The 

 upper part of the parapet is lower with- 

 out than it is at the crest X. This decli- 

 nation, which is called the superior slope, 

 is at the rate of one inch for every foot 

 the parapet has of thickness, so as to al- 

 low the defenders to fire at an enemy al- 

 most close to the rampart, yet not to weak- 

 en the crest. K, shews a revetement of 

 masonry, which should be five feet thick 

 at the fop of the rampart, not including 

 the parapet, but measuring at the upper 

 cordon O. The exterior slope of the 

 revetement should be one sixth of its 

 height, taken from the foot to the cordon. 

 The foundation should project in pro- 

 portion to the height, and to the nature 

 of the soil. The interior slope of the 

 parapet, and the banquette, are like- 

 wise bounded by a revetement in this 

 figure, but such is not always the case ; 

 when it is, the ascent to the banquette 

 is made by two or three steps, as here 

 shewn. Nor are all parapets faced with 

 masonry ; the generality, indeed, are 

 gazonedj or turfed, on account of the in- 



calculable injury done by the splinters 

 knocked off by such shots as graze up- 

 on masonry of any kind. In some in- 

 stances, only half revetements are used, 

 that is, only for the scarp, or face of the 

 ditch, as seen at M under the cordon O ; 

 the whole exterior of the rampart itself 

 being gazoned. The interior slope of 

 the rampart, when made of masonry, 

 as seen at P, where the counterscarp is 

 carried up, or built upon, to form the 

 interior slope of the counter-guard B, 

 may be equal to only one-fifth of its 

 whole height ; but where masonry is not 

 used, the interior slope, as at L, of the 

 rampart A, should, if the soil be firm, 

 be equal to the height of the rampart, 

 which would give an angle of 45 de- 

 grees: when the soil is sandy, crumbly, 

 or apt to give way, the interior slope 

 should be equal to a height and a half, 

 or even more, if circumstances should 

 require. The continuation of the revete- 

 ment M, above the cordon O, which is 

 level with the terre-pleine of the berm 

 N, is a firm parapet, made in lieu of the 

 exploded fausse-braye, to prevent the 

 ruins of the rampart A, when breach- 

 ed, from falling into the ditch C; of 

 which the breadth is indefinite, though 

 from 15 to 25 toises may be consider- 

 ed as the limits for works, according to 

 the mean and great systems of Vauban. 

 About the middle of the ditch, but ge- 

 nerally rather more towards the coun- 

 terscarp P, than towards the scarp M, 

 is the cunette, or cuvette, about 15 feet 

 broad, rivetted throughout, and from 

 .six to nine feet deep. It is always kept 

 full of water, where that may be prac- 

 ticable; and, as it goes entirely around 

 the body of the place, serves to pre- 

 vent a surprise, to restrain from deser- 

 tion, also from an improper access to 

 spirituous liquors, and as a drain to the 

 body of the ditch. In many instances, 

 very fine supplies of fish are obtained 

 from the cuvette. In some fortresses 

 it is cut oflT from before the curtains by 

 rows of palisades, standing on a shelv- 

 ing work, called a batardeau. Where 

 it is continued before the curtains, there 

 must be bridges of communication ; and 

 small temporary plank passages are 

 made over in various parts, when occa- 

 sion may require. All ditches should 

 be sown with good grasses, that they 

 may give a supply of that valuable com- 

 modity to such horses, &c. as may be 

 kept in the fortress ; and all gazoned 

 facings, as well as the slopes of para- 



