LOOPHOLES FOR FIRING. During an attack, firing is never possible through loopholes as it is too restricted to be of any value. All the firing then is done over the parapet. The difficulty of constructing new observation posts which are effectual and inconspicuous for any length of time has resulted in their not being made in a parapet, where, when located by the enemy, they are as often as not a source of danger. Moreover, promiscuous firing through loopholes by inefficient riflemen is of no value. Sniping is under the control and supervision of a sniping officer, and loopholes should only be used by men appointed by that officer. They are not used at night and should be only used during the day for enfilade fire, and be placed in the parapet as low down as is consistent with line of site. A piece of cloth or empty sandbag should be hung from the rear of the loophole, so that when the hole is not obstructed by the fire, no light can show through. No shots should be fired from those loopholes, except at a definite target, and ranges of targets or spots where targets may possibly appear, should be ascertained in advance, and necessary exposed movement, such as withdrawal of rifle, must be very slow and gradual. With care, and when only used by a skilled rifleman, a loophole will be of value for probably two weeks and good results obtained, but by a careless man the value of a loophole will not last a day and very likely result in casualties not only to the man shooting, but to others as well. In the area from 20 to 100 yards behind the fire trench, there sometimes is, although very seldom, ground much higher than the actual fire trench, so that it is safe to allow even hastily trained men to use it for firing over the heads of the main front line trench, although it has happened that men in such a position have fired into their front line, thinking it the enemy line. This ground is generally used by building what are known as covering fire trenches. These to be of any value, should not be more than 20 yards behind the front line, as farther forward than 20 yards they become affected by artillery fire directed at the fire trenches; and farther back than 100 yards the covering fire, unless in the hands of very skilled and efficient riflemen, becomes very dangerous to the men in the front line. SUPPORT TRENCHES AND SUPPORT DUGOUTS