No attack is possible if the Command is not daily informed by the photographic section. Even after a continuous bombardment it is more prudent to defer an attack if during the preceding days the weather has been so bad as to prevent the use of the aërial cameras. USE OF SCOUT-PLANES TO DIRECT ARTILLERY FIRE. Special and sufficiently numerous squadrillas must be reserved for the exclusive use of the artillery, and more particularly for that of the heavy artillery in order to supply them with the proper range. At times, captive balloons can help the heavy artillery in this respect, the gunners preferring them to airplanes; but these balloons are not always sufficiently numerous and cannot always see far enough. The guiding airplane informs the batteries to which it is assigned of the effect of their shell-fire by means of wireless telegraphy, which has the advantage of not being interrupted by the terrific noise of the bombardment, whereas telephonic communication with a captive balloon is impossible without the use of special “hearing masks.” Different kinds of rockets can also be employed for indicating the range under certain circumstances. USE OF SCOUT-PLANES TO DIRECT THE MOVEMENTS OF INFANTRY. The squadrillas of a Division are provided with devices for guiding the movements of infantry. Their duties are manifold. At all times they are kept hovering over the first lines to watch the enemy and give warning of all unusual moves. During an assault their principal duty is to secure the indispensable unity of action between the infantry and the field artillery. As we will explain further on, every attack made by the infantry is screened by a terrific barrage fire that advances about one hundred yards ahead of the first wave. In order that such a barrage may continue to be properly effective it must progress at the same speed as the infantry. For this purpose scout-planes are equipped with a special rocket, that signals, “Increase the range.” Each rocket sent calls for an increase of one hundred metres in the range. During the fight the duties of the aviator as watchdog of the infantry do not cease. He has to observe the slightest moves of the enemy, and he is usually able to warn his commanders of the preparation of counter-attacks, of their direction, and of their strength. The services rendered by the guiding aviation to the artillery and infantry are obviously of capital importance. Its mission, if properly executed, is extremely hard and laborious, hence the necessity, in the future, of increasing the number and efficiency of these squadrillas as much as possible. In order that they may operate successfully they must be closely protected by powerful battle-planes, unless the latter have already cleared the region of enemy machines and left them the mastery of the air.