=9. Cover and Fields of Fire.=--(i) Owing to the effect of German artillery fire, cover from view has become more important than field of fire. It is better to have a field of fire of 100 yards and to be invisible than to have one of 600 yards and be an easy target for artillery. Owing to the enemy’s artillery fire by day, digging is nearly always done at night, and this requires much practice. Some sort of rough cover from shrapnel and head cover is made if time allows, and also if it can be made without making the trench conspicuous. (ii) =Defensive Positions and Sites of Trenches.=--Whenever possible, trenches should be sited so that they are not under artillery observation. This point is regarded as of great importance, and an extensive field of fire is a secondary consideration. Trenches should therefore be sited having regard to possible observation stations on ground occupied by the enemy, and not solely with regard to the possible artillery positions of the enemy. In open country it is better to select a “back position,” behind the crest of a hill, with a field of fire of 300 or 400 yards. This compels the enemy to expose his infantry to rifle and shrapnel fire, and affords his artillery little opportunity of observation. Such positions were held on the Aisne, with slight loss to our troops and heavy loss to the enemy. A field of fire of 100 yards is regarded as satisfactory if it cannot be increased without loss of concealment from artillery observation. =10. Care of Rifles.=--(i) The following directions are issued with regard to the care of rifles on service. New rifles are inclined to work somewhat stiffly at first, owing to slight roughness of the bearing surfaces of the bolt and bolt-way. This can be appreciably lessened by frequent and systematic manipulation of the bolt, the bearing surfaces being well oiled. Primary extraction--the first loosening of the fired cartridge in the chamber--can be improved by placing a fired case in the chamber, and working the bolt-lever up and down without drawing back the bolt. (ii) Rifles must be kept clean and well oiled, and it has been found necessary to make an inspection daily or even oftener. Particular care must be taken to see that the chamber is scrupulously clean. If it is permitted to become dirty, great difficulty in extraction is likely to be experienced. It has also been found that cartridges get rusted into their clips, and that they should be moved at least weekly. Magazine springs may also become weak, if the magazine is continually kept loaded with ten instead of five rounds.