belonged to that corps, he furnishes an individual proof at least that the French engineers could not boast of superior information in their profession. Even with regard to the composition of his sentences, his style appears to us either uncouth or incorrect; and the phraseology strikes us as according but little with the idiom not only of the French language but of any other. Yet the Baron considers his work (preface p. 15.) as truly classical; comme un livre vraiment classique.

M. DE F. V. divides his subject into three principal parts; viz. the sections of the works of a fortification, and particularly of the body of the place, which he terms la formation essentielle,' the construction of the body of the place, as the rampart, &c. which he chuses to call le developpement complet ;' and the construction of outworks, to which he gives the name of redoublements additionels. To the first of these objects he devotes three chapters, from page 1 to 77; to the second, three more, from page 78 to 162; and to the third, two, from page 163 to 215. To these eight chapters he adds a ninth, on the influence of fortified places in the general system of warfare, their positions, their size, their proximity, and their number.

Contrary to the invariable practice of writers on fortification, as well as (we think) to the dictates of common sense, he begins with the orthography of military works, or a description of their sections or profiles, before he treats of the ichnographical part of construction, or even shews how they are to be traced out: a mode of proceeding which, (though in page 13 of his preface he calls it his marche precieuse,') instead of facilitating the studies of young gentlemen who are learning the principles of that art at the Royal Military College, is peculiarly calculated for retarding their progress, for disgusting them, and for giving them confused ideas on the subject. The writer does not seem to be aware that the developement of the design of any work, or erection, comprehends both an ichnographical and an orthographical delineation of it, or a representation of all its faces, profiles, and parts.-Although he says that he has not ventured to hazard any opinion of his own, nor to propose even the smallest innovation in an art so delicate as that of fortification, he gives both dimensions and slopes in his profiles that are different from those which are used by the Marshal De Vauban in the works which he erected; at the very time, too, that he is professing the most profound veneration for the Marshal, as the prince of fortifiers.

In Chapter IV. the Baron uselessly employs 27 pages in shewing that the enceinte of the body of a fortified place ought to be composed of curtains and bastions, or of curtains, flanks, and faces.

He

He finds great fault, and perhaps justly, with the Marquis De Montalembert, for wantonly rejecting the bastioned system, which has been used in almost every nation of Europe ever since the introduction of the modern method of fortification : but he does not seem to be sensible that the Marquis's construction has nothing new in it, being the same with that of M. Blondel on a right line, or on a polygon of an indefinite number of sides: for if n denote the number of the sides of the figure or polygon, the angle diminué by Blondel's method will be generally and truly expressed by 45°

125°

n

; and it

120°

is evident that this expression, when n is indefinitely great, or when the angle of the figure or polygon approaches indefinitely near to an equality with 180°, is indefinitely near to an equality with 45°. Of course, his construction on a right line gives the angle diminué equal to 45°. In this case, both constructions make the perpendicular equal to half the exterior side, the angle diminué equal to 45°, the flinked angle equal to 90°, the same line of defence, the same flanking or re entering angle, and no curtain. The only difference between them consists in this, that M. Blondel, in descending from the right line, which may be regarded as part of a polygon of an indefinite or infinite number of sides, to inferior polygons, makes his angle diminué gradually decrease with the general expression 45°- for its magnitude; whereas the Marquis keeps his angle in all figures invariably the same, or equal to 45°. Baron DE FACES VA AUMALE, however, censures him and his system in general terms, without pointing out, like a professional man, its defects or its inferiority to that of Vauban, which has been generally, and still is, followed with very little alteration. He has not drawn any rational, scientific, or satisfactory comparison be. tween the Marquis's Fortification perpendiculaire and Vauban's first method; nor between the triangular construction, whether the re-entering angles be right, acute, or obtuse, and the bastioned system in general. He has not shewn, by means of any such comparative account of them, that the last, when properly constructed, leaves no dead or unseen parts; and that the first, with a section even moderately high, unavoidably creates such parts throughout the whole extent almost of the enceinte, or length of inclosure, and is equally destitute of flanking fires for itself, and of a good or well-distributed direct fire against the enemy. Nor has he made it appear that, in consequence of such a continuity of dead parts, an enemy can approach the body of the place without annoyance from the besieged, in lines bisecting either the saliant or the re entering angles, or even

in lines directed to any intermediate points between these angles.

365

Moreover, the Baron has not shewn that Montalembert's construction gives the flanked angle, even in a polygon of eigt en sides, equal only to 70°, which is the smallest that is adinissible in fortification. This, however, is demonstrable in the following manner. As in it the lines of defence, when equal, form angles of 45° with the exterior side, each of the saliant angles in any figure or polygon is equal to 90°(n denoting the number of the sides of the figure or polygon): but it is manifest that this expression gives for the square no saliant angle; for the pent gon, one of 18° only; for the hexagon, one of 30° only; for the heptagon, one of 38; for the octagon, one of 45°; for the enne gon, one of 50°; for the decagon, one of 44°; for the endecagon, one of $7°; for the dodecagon, one of 60°; for a polygon of 18 sides, one of 70°; and so on. The present author does not appear to have even understood the principal defects in this construction: for he has not laid before his readers for their information, nor even so much as hinted at, the following important and leading circumstances, which unavoidably arise out of it:

1st. That the Marquis is obliged to have recourse to a number of expensive casemates, with embrasures and loop-holes, in order to remove the very dead parts necessarily occasioned by his construction.

2dly. That his saliant angles are too small, being less in a dodecagon than those of Vauban are even in a square.

3dly. That it furnishes no fire which is direct or perpendi cular to the exterior sides.

4thly. That, opposite to each re-entering angle, at the distance of go toises only from the exterior side, is a quadrangular space commanded by no fire, commencing in an angle of 90°, and terminating in one of 30°, at the same distance from the exterior side with the centre of the dodecagon.

5thly. That, opposite to every saliant angle, and at the distance from it of about 2541 toises only, is a space that is not scoured or commanded by the fire of the place; which commenc s in an angle of 60, widens till its breadth becomes equal to the radius of the circle circumscribing the dodecagon, and then runs on indefinitely at that width between parallel lines.

6thly. That the greatest width of each of the first-mentioned spaces, not traversed by the fire of the place, is to the corresponding width of each of the spaces traversed by it, as 104 to 147 nearly; and that the greatest width of each of the lastmentioned spaces, not traversed by that fire, is to the corresponding

ponding width of each of those that are traversed by it, as 264 to Ico nearly; and consequently that the greatest widths of the spaces not traversed by the fire of the place are, taken together, to the corresponding widths of those that are traversed by it, as 3432 to 18374 nearly.

7thly, That, as the distance between every two of the spaces is only equal to one of his lines of defence, or to 127,2794 toises, the besiegers may advance almost to the very crest of the glacis, without any interruption from the fire of the besieged; contrary to an important object in defence, which is to keep the besiegers at a distance from the body of the place as long as possible, since they will infallibly silence artillery whenever they come within the range of serious musketry from it, whether the embrasures be open or covered at top, or whether the guns be in casemates or not.

8thly, That the besiegers may easily destroy his principal covered musketry defences, before they are exposed to his principal casemated defences with artillery; which, being low, in order to take off the dead parts unavoidably occasioned by the very nature of his construction, are chiefly calculated for defending the passage of the ditch, and cannot therefore annoy an enemy till he gets to the very crest of the glacis: after which, almost every thing, except battering in breach, is deter mined without artillery.

9thly, That, even in a dodecagon, the annular area occupied by the Marquis's construction between the circumscribing and the inscribed circle is equal to half of the whole area of the greater of these circles; whereas the annular area occupied by those of Vauban is to the area of the said circle only as 20 to 69, or is considerably less than a third part of it.

Lastly, That the great proportion which this annular area, Occupied by his construction, bears to that of the inscribed circle, will for ever render it unfit for the purpose of fortifying any considerable town or city.

Our surprise, however, that Baron DE FAGES VAUMALE does not understand the Fortification perpendiculaire of Montalembert sufficiently to point out its radical and principal defects, and that he is right by mere accident only in reprobating it in general terms as repugnant to the customary method of construction, must cease when we find that in page 104 of his work he manifests so much ignorance in defining the common and well-known angles in fortification, as to mistake some of them for one another, and to give erroneous definitions of them. Thus, for instance, he mistakes the flanking angle (angle flunquant) for the angle of the curtain, or of the flank, dehning it to be l'angle formé par le flanc et la courtine, the angle formed APP. REV. VOL. LVI.

Kk

by

by the flank and the curtain. He seems not to know that the outward flanking angle and the angle of the tenaille, formed opposite to the exterior side by the lines of defence at their intersection, or by the two opposite faces of two bastions produced to meet each other, are with the writers on fortification one and the same; and in consequence of not knowing this he gives different definitions of them, as if they were actually different confounding together angles that are perfectly distinct, and furnishing inconsistent and discordant definitions of one and the same angle. Belidor defines the angle of the curtain in these words; "celui qui est compris par la courtine et le flanc," that which is comprehended or contained by the curtain and the flank; and Muller defines the angle of the flank to be that which is made by the curtain and the flank. Even Mr. Landmann, the professor of fortification and artillery at Woolwich, was not so inadvertent as to commit so very glaring a blunder: for the following is one of his definitions: "the flanking angle, or angle of tenaille, is the exterior angle formed by the intersection of the two lines of defence."

We cannot help lamenting on this occasion the truly deplorable state of military instruction in this country, while we are at war with most of the powers of Europe. We have clearly seen, by a recent publication, that Mr. Landmann has for a series of years been in the practice of directing the cadets in the Royal Military Academy at Woolwich, even in constructing Vauban's first method, to do things that are not only inconsistent but demonstrably impracticable. How, then, can it have been possible, during this period, for that academy to produce young men properly qualified for becoming either engineers or artillery officers? In the work now before us, we see a professor of fortification in the Royal Military College at Great Marlow, and who styles himself at this moment a captain in the French corps of Royal Engineers, confounding together the angles commonly mentioned by the writers on this subject, and giving wrong definitions of them. Now if the Baron really be at this moment a captain in that corps, he ought not to be in this country; and if he ever did belong to it, the officers at present composing it must be inexpressibly mortified on looking into this performance, should it ever fall under their notice: though it may at the same time be some political consolation to them to know, that such a person is intrusted to teach fortification at an establishment professedly formed for the improvement of the British army. Several individuals have attributed much credit to our Commander

See our Review for July last.