The subject will be treated under the following heads:-- I.--HOW POSTED WITH RESPECT TO THE GROUND. II.--HOW POSTED WITH RESPECT TO OUR OWN TROOPS. III.--HOW POSTED WITH RESPECT TO THE ENEMY. IV.--POSTING OF BATTERIES AND PIECES AS BETWEEN THEMSELVES. V.--HOW USED. VI.--ITS FIRE. VII.--ITS SUPPORTS. I.--How posted with respect to the Ground. 1. Artillery has a much longer range than musketry. In order to avail ourselves of this advantage, we must so post it as to overlook all the ground to which its utmost range extends. It therefore requires _an elevated position_. 2. It has been considered an additional advantage of a commanding position for artillery, that it enables our guns to cover our infantry, attacking or attacked, by _firing over their heads_. This was done by the French at Waterloo, apparently with great effect. But the advantage is a doubtful one; for firing over our own troops, especially with cast-shot or shell, is very dangerous to them, and is apt to intimidate them. It moreover furnishes to the enemy a double target. The shot which miss our troops will be apt to fall among the guns behind them; and some of those which do not reach the guns, will probably take effect among the troops in front of them. 3. But _very high_ points are unfavorable positions for batteries. Batteries so placed would not command the ground immediately below them; as guns cannot be depressed to fire below a certain angle without soon destroying their carriages. And this would facilitate their capture; for, once arrived on the ground near them, the assailants could not be injured by their fire. It has been estimated that the slope in front of a battery should not exceed one perpendicular to fifteen base. 4. When guns have to be used as a support to other parts of the line, which is often the case, their capture might lead to serious consequences. They should therefore have the ground clear of all obstacles which may _mask their fire_, not only in front, but to their right and left. 5. Although the most favorable position for guns is an eminence sloping gradually towards the enemy, an _open and level plain_ is by no means an unfavorable one; for, on such ground, the enemy will be visible at a great distance, and our shot may act by ricochet, which causes more destruction than ordinary point-blank firing. For ricochet, firm and even ground is requisite; on soft or rough ground it is not attainable. 6. In enfilading the enemy's position, or in raking his advancing columns from head to rear, a _grazing fire_ is the most destructive that can be used. This consists of a long succession of ricochets at low heights. Where the ground is level and firm, we can obtain this fire at a short distance from the enemy; as, on such ground, ricochet shots do not rise much. But where the ground is uneven, to obtain such a fire, a more distant position will be requisite.