7. When teaching the use of cover, the instructor will explain that the first principle is so to adapt the position to it that the rifle can be fired with the minimum of exposure. He will then state the advantages and disadvantages of various kinds of cover, and will point out that a firer behind a rock or stone wall may be wounded by splinters; that a certain thickness of earth or brick is necessary to resist a bullet; that a tree affords only moderate protection; that an isolated tree, bush or hedgerow should be avoided as it will probably draw fire; that even the smallest fold of ground gives cover from view and protection from fire, &c. Finally, he will, so far as cover is available, practically show how each can best be utilised. The men will observe his position both from behind and from the front, and the instructor will emphasise the danger of undue exposure. Each man will then be directed to take cover, and his actions and position criticised by the instructor from the enemy’s point of view as well as from behind. 8. If a skirmisher finds that there is no cover near his line of advance, or that the cover which exists is already occupied, he must throw himself down in the open, and lie as flat as possible. 9. Skirmishers must never expose themselves on the sky-line, or against a background which would show them up; they must never in any circumstances crowd together. 10. It will be found of great value during instruction to make each individual man skirmish independently over a piece of unknown ground against the rest of the squad, and to invite their criticism on his action. 11. In training skirmishers it is by no means sufficient to point out mistakes, but, in every case, the correct method of action, and the reasons for it, should be carefully and patiently explained, and the exercise repeated. =52.= _Blank Ammunition._ Blank ammunition should occasionally be used, and the enemy should be represented by either another squad, or a few men; light canvas, paper, or wooden targets, in the form of men kneeling, cavalry, a gun, &c., &c.; or a line of old helmets or khaki hats. =53.= _Fire Effect._ 1. In skirmishing the unit of fire will usually be the section or squad. 2. The squad leader will be careful that no man who cannot see the mark fires. 3. The instructor should constantly inspect the recruits when firing from behind cover, direct them to correct their positions, and make certain that they recognise the target at which they have been ordered to aim. It will be explained to the recruits that-- (i) Fire is only effective when the mark can be seen, and when it is steadily delivered. (ii) It is useless to fire merely for the sake of firing, when no enemy is visible, and his position is unknown.