Observation of the enemy's line should be continuous. The observation and firing system will be arranged so that all parts of the enemy's line will be under observation and fire at all times.
Plate 42 shows the arrangement in general. The appliances for carrying it out are shown in Plates 43, 44 and 45.
Plate 43.
The observation is conducted through a small loophole made by a stick through the parapet or an iron tube run through and directed toward the point to be observed. To conceal the exit a few tufts of earth and grass are placed there in an irregular manner. Steel loopholes may also be employed for observation and firing purposes. They may be arranged a yard or two apart, so that one man observing through one can direct his mate using the rifle at the other so that he may bring fire to bear upon any member of the enemy's force that exposes himself at the point under observation.
The loopholes, both observation and firing, are arranged slantwise in the parapet so that the observer does not look straight to his front nor does the firer fire in that direction.
