When the parapet over which the shot is to Fun has little elevation above the battery, it requires considerable charges to allow the vertex of the trajectory to coincide with the crest ; but the charges diminish rapidly as the height of the parapet increa.ses, or as the distance of the battery from thence diminiehes : the effect of this is to produce the kind of ricochet first mentioned above, for the angle made by the descending branch with the horizontal ground being greater, the re bounds of the shot are more numerous within a given extent of ground, and between the successive grazes the curves are higher and shorter. In thiscase, and when the descending branch passes through the crest, the shot falls almost immediately behind the parapet, and no part of the ground to be ricochetted ia free from its action : this is not always certain, when by great charges and low elevations the and kind of is used, since it may happen that the shot will pass above the objects which it should strike within the limits of the ground. In the modern system of fortification the greatest length of the faces of works which arc liable to the ricochet ia about 100 yards; therefore when there are no traverses on the terreplein, and it is merely required to strike an object somewhere between the crest of the covering para pet (supposed to be about 8 feet high) and the further extremity of any such face, the descending branch of the trajectory will make with the horizon an angle of about one degree, and the charge and elevation of the gun should be determined so that this condition may be fulfilled. From shot so fired a traverse near the covering parapet would entirely protect the ground, since the projectile would lodge in it, and do no harm to the defenders; and in order that the fire of shot may do execution, whether made in that manner or with an increased elevation of the piece so as to produce ricochets, it is nocesm- ry previously to destroy the traverse by shells fired as above described. For such a purpose General Millar's 3-inch howitzers will probably be found to be the most serviceable; and if the large shot an uently fired k-ricochet to dismount the artillery should not succeed in c g an enemy's work of the troops who defend the parapet, spherical case shut fired from 24 pounder guns might be advantageously employed. One gun in a ricochet battery should be exactly in the prolongation of the crest of the parapet on the face to be enfiladed, In order that Its shot may graze, with the long ricochet, the interior slope of such parapet.
Experiments do ricochet firing were carried on at Woolwich, in the months of June and October, 1821, when a work 100 yards long, and resembling the face of a bastion or ravelin, was entiLuled In that manner with iron and brass ordnance of different natures; the covering face was eight feet high, and its crest was nearly on a level with the axes of the guns in the battery. The results were, that with a range equal to 400 yards, and a charge of powder equal to of the weight of the shot, about two-thirds of the number of rounds took effect ; et 600 yards, with charges varying from A to of the weight, from one-third to one-half took effect ; and at E00 yarda, with charges from to between one-third and two-thirds took effect It was concluded there fore that ricochet batteries ought, if peasible, to be st a distance vary ing from 400 to 600 yards from the nearest part of the line of rampart to be enfiladed; for beyond the latter distance the effect of the fire is uncertain. The long ricochet, with high charges and small elevations
or depression, of the guns, may, however, be advantageously employed in tiring from the rampart+ of a fortress on the ground in front, or against extensive lines of works when the battery is at a much greater distance.
It appears from the experiments above-mentioned that the beet elevations of onluance for enfilading a work h-rieochet with shot or shells is that in which the axis of the piece is directed at an angle varying from 6' to is' above a line drawn from the chamber of the gun or howitzer to the crest of the parapet over which the projectile is to peat It is stated that of 170 shells filled with powder which were fires]. 53 took effect, but only 83 burst in the work. Before the traverses were constructed several guns on the work were struck and rendered useless; but afterwards, though the traverse* were much injured, none of the guns protected by them were disableL When employed against troops in the field, ricochet firing is found to he of essential service ; for the shot making on the ground eight or ten grazes, It cannot fail at some of these to take effect. In 1757, the King of Pruslia had several Nix-inch mortars mounted on travelling carriages; and from these he causal shells to be thrown Is-ricochet, in an obhqne direction, against the enemy's line, which It immediately put in great disorder.
Ricochet firing, when first employed In sieges, from the defenders not being prepared with means to diminish its destructive effects, pro duced immediately a strong impression of its power ; and the opinion of its superiority to the direct mode of firing has oontinned to prevail from the time of Vauban to the present day, though the service of artillery ia now so precise, that when the guns in an enemy's work can be seen, they can be as readily dismounted by the latter mode as by the ricochet. It ought also to be remembered that before the latter can be usefully employed, the parapets, traverses, or blindages which cover the artillery of a fortress must be rthned by other means; and it may reasonably be concluded that the rapid reduction, or the most protracted defence of a place, will always be owing to a judicious com bination of the different modes in which, according to the circum stances, artillery can be used during the siege. [SIEGE.] Though it has been stated that with Mr. Whitworth's rifle gun some very good ricochet practice has been made, it is very doubtful whether rifle cannon can be employed for this purpose, as from the rotation of the shot it is deflected immensely on striking the ground. In fact, this is one of the disadvantages of rifle guns.