The above proportions are taken from Durtubie’s Manuel De l’Artilleur. The following method of regulating the management of the artillery, and estimating the probable expenditure of ammunition in the defence of a fortified place, is extracted from a valuable work on fortification lately published at Berlin. It is particularly applied to a regular hexagon; the siege is divided into three periods, _viz._ 1st. From the first investiture to the first opening of the trenches, about 5 days. 2d. From the opening of the trenches to the effecting a lodgement on the glacis, about 18 days. 3d. From this time to the capitulation, about 5 days. _First Period._ Three guns on the barbette of each bastion and on the barbettes of the ravelins in front of the gateways, half 24 Prs. and half 18 Prs.[4] three 9 Prs. on the barbette of each of the other ravelins. Twelve 12 Prs. and twelve 4 Prs. in reserve. One 13 inch mortar in each bastion. Six of 8 inch in the salient angles of the covert way. Do. in reserve. Ten stone mortars. [4] For 16 Prs. in the French work, the compiler has said 18 Prs.—for 8 Prs. 9 Prs.—for 12 inch mortars, 13 inch; to which they nearly answer. The 12 Prs. in reserve, are to be ranged behind the curtain, on whichever side they may be required, and the 4 Prs. in the outworks; all to fire _en ricochet_ over the parapet. By this arrangement, the whole of the barbette guns are ready to act in any direction, till the side of attack is determined on; and with the addition of the reserve, 49 pieces may be opened upon the enemy the very first night they begin to work upon the trenches.