This training forms a basis from which other methods of control can most easily be evolved, and inculcates into the men the necessity for assuring themselves that any orders received by them are passed on by some means to those concerned. “INDICATION AND RECOGNITION.” The methods of “indication and recognition,” as taught at Hythe before the war, have proved most useful. This fact has been brought out in the accounts of the most successful machine gun actions, as has also the great value of the use of range cards and indication points. Targets are generally easy to indicate, as men are more alert than in peace-time. Training in indication, recognition, fire orders, and judging distance, can be given at any time, as no apparatus is required. This is also valuable, as it trains all ranks in a quick understanding of directions given, study of ground, and trains the eye in quick observation. WORKING GUNS IN PAIRS AND INTERVALS BETWEEN GUNS. The necessity of using guns in pairs for mutual support in case of mechanical trouble no longer holds good. Guns in the open have usually been placed not less than 50 yards apart. This enables the best use to be made of the ground as protection against artillery fire and for concealment. In trench warfare guns should usually be placed singly, arrangements being made for “cross fire” and mutual support between the guns of any particular section of the defensive line. OBSERVATION OF FIRE. Observation of fire has usually been obtainable up to 900 yards, and in favourable circumstances at even longer ranges. Even when the ground has been unfavourable, observation has often been obtainable on water, walls of houses, enemy’s parapet, etc. OVERHEAD FIRE AND CONDITION OF GROUND. During the fighting on the Marne and on the Aisne, guns were often able to support the infantry advance to within 100 yards of the enemy’s position. Even on flat ground frequent instances are given where overhead fire has been used, with excellent effect, from buildings. On the whole it would appear that not enough use is made of this fire. This is a question that should be carefully studied by all Machine Gun Officers. INDIRECT FIRE BY GRATICULES, LEVEL, AIMING POSTS AND OBSERVATION.