In enumerating the various kinds of projectiles that may be used in defending a place, Carnot also recom mends common artillery in certain circumstances, but thinks they should cot be fired through embrasures, at least if they are mounted on the faces. Instead of these he proposes temporary merlons, consisting of bags of earth, to be used till the enemy opens his ricochett bat teries, after which the artillery is to be withdrawn. Gre nades, he thinks, might also be used with great advantage, and even in some cases the many balista and scorpion of the ancients. There is still another kind of artillery, how. ever, which, from its singularity, merits attention. It was first suggested by M. Flachon de la Jomariere, and con sists in discharging an immense quantity of water, by means of pumps, on the works erected by the enemy on the crest of the covert way. By this means Iomariere supposed that the earth would be so completely soaked, as to put a stop to their work. " It would not be difficult to conceive," says Carnot, " that this idea was every where turned into ridicule. It was however decreed by govern ment, in 1785, to put the plan to the test of experiment, and that experiment, to the utter confusion of the sarcasm makers, completely succeeded. The sappers could no longer fill their baskets; the earth was converted into a liquid mud, which slipped from under them, and of which it was impossible to construct any intrenchment. Yet, not withstanding all this, the experiment has never been fol lowed up ;—a proof that it is not always sufficient to have experience, reason, and even the good of the state on one's side—the inertia of indolence may resist all these. Per haps an age or two hence, some extraordinary events may show, that the idea is neither extravagant nor absurd." We should not be surprised if the sentiments which Car not has expressed with regard to Jomariere's plan of de fence, are hereafter found to be strictly applicable to his own.
As might be expected from what has been already stat ed, the present construction of fortifications is, in the opinion of Carnot, extremely defective. Of these defects he has given an enumeration, and has also illustrated them at considerable length.—They are as follows:— 1st, There is no provision made for covering either the artillery, or the garrison on duty, from the fire of the enemy. In consequence of this, the guns of the fortress are generally dismounted in a few days.
2d, There is no interior work or intrenchment, so that whenever the besiegers make a successful assault, the place is in their power, and the inhabitants exposed to pillage.
3d, The communication between the different parts of the place and the outworks, is too difficult for the prompt execution of any necessary movement. As an improve ment in this respect, Carnot proposes, that instead of a wall in the counterscarpe, there should be a gentle slope or glacis, from the covert way to the bottom of the fosse, so that if the besiegers should get possession of the former, the besieged might make an attack upon them at any point, where they had the greatest prospect of success. Should it be objected to this construction that it would enable the enemy to advance without interruption to the bottom of the enceinte, Carnot justly observes, that it is not advancing thither, but establishing themselves there, that is to be dreaded ; and this they would not easily do without im mense loss from the fire of the place.
4th, The covered way is not constructed so as to answer the purposes for which it is intended. These arc, 1. To collect the force that may be sent to the assistance of the place. 2. To form the troops intended for a sortie. 3. To serve as advanced posts for preventing surprises. 4. To cover by its parapet the revetment of the works : And, 5. To furnish a second line of fire to the enceinte. On the first of these our author observes, that the covert way being hid by a pallisade towards the field, it is a matter of great difficulty for the auxiliary troops to find out the point where they can enter it, and even after they have entered it, if they consist of cavalry or artillery, it is equally diffi cult to find admittance into the place. For the same reason it obstructs, rather than assists, a if the sallying force consists of cavalry. As to preventing sur prises, it is, in its present form, of \ cry little use, as the besiegers can, in a few minutes, make their way over flu pallisade, by means of their fascines, and that too with scarcely any noise. In covering the revetement of the works, it might be useful, if its parapet were higher than the revetement ; but it is well known that, in the greater part of modern fortifications, this is not the case ; and, with regard to its affording an additional line of fire, it is obvious that, as the besiegers are always covered by parapet, the rasing fire which the covered way affords eau be of little value. Many of these disadvantages would be avoided, by substituting a glacis for a revetted couLt(:.r scarpe, as already described.
5th, In the present construction of fortified places, the ravelin does not completely cover the shoulders of the bastion, so that the enemy can reach them with his fire through the openings of the tenaille.
6th, The escarpe is too much exposed.
7th, There is no means of having a fire directed :dons• the capitals of the saliants, on which the enemy's ap proaches are generally constructed.
8th, The fall of the revetement at the time of the breach, generally drags with it the whole of the parapet, which greatly facilitates the assault of the enemy. This might be remedied by having a way of rounds, though that too has its inconveniences.
9th, The masonry of the works, on account of their talud, or slope, is easily worn clown by the action of the weather.
10th, The place, in general, is not furnished with suffi• cient souterrains for protecting the men and the ammu nition.
1 lth, The present system of defence requires a much greater quantity of wood than can in most cases be pro cured : And, 12th, It exposes the soldiers to severe and incessant labour, without the possibility of their obtaining necessary repose.
The great length to which this article has already ex tended, prevents us entering so largely, as we should other wise have clone, on the system which we have now endea voured to sketch. From the preceding observations, how ever, our readers will readily perceive, that the work is not unworthy of its distinguished author, and that the prin ciple which it unfolds is peculiarly deserving the attention of engineers.
See Vauban, Traite de l'./Ittaque des Places. Carnot, De la Defense des Places Fortes, Paris, 1812, Ste.
See MILITARY ARCHITECTURE, for the subject of Cas trametation, and other topics connected with the preceding article.