The first arrangement of the artillery at a siege is to the different batteries raised near the first parallel, to enfilade the faces of the work on the front attacked, which fire on the approaches. If these first batteries be favorably situated, the artillery may be continued in them nearly the whole of the siege; and will save the erection of any other gun batteries, till the besiegers arrive on the crest of the glacis. It however frequently happens, from local circumstances, that the besiegers cannot avail themselves of the most advantageous situations for the first batteries. There are four situations from which the defences of any face may be destroyed; but not from all with equal facility. The best position for the first batteries, is perpendicular to the prolongation of the face of the work to be enfiladed. If this position cannot be attained, the next that presents itself is, on that side of the prolongation which takes the face in reverse; and under as small an angle as possible. From both these positions the guns must fire _en ricochet_. But if the ground, or other circumstance, will not admit of either of these being occupied by ricochet batteries, the battery to destroy the fire of a face must be without the prolongation, so as to fire obliquely upon the outside of the face. The last position, in point of advantage, is directly parallel to the face. From these two last positions the guns must fire with the full charges. The second, or breaching batteries at a siege, are generally placed on the crest of the glacis, within 15 or 18 feet of the covert way; which space serves as the epaulment: but if the foot of the revetment cannot be seen from this situation, they must be placed in the covert way, within 15 feet of the counterscarpe of the ditch. These batteries must be sunk as low as the soles of the embrazures, and are in fact but an enlargement of the sap, run for the lodgement on the glacis or in the covert way. In constructing a battery on the crest of the glacis, attention must be paid that none of the embrazures open upon the traverses of the covert way. These batteries should consist of at least four guns; and if the breadth between the traverses will not admit of this number, at the usual distances, the guns must be closed to 15 or 12 feet from each other.