He will first need to identify them. That is to say, he must be able to determine whether he is looking at infantry, cavalry, or artillery; and then he must be able to decide as to the strength of the forces that are in view. These points determined, he will turn again to his map, so as to make sure of the actual point, on the battle line, where the troops he sees are stationed. This done, he will make notes in his book. And so, throughout the flight, will the observation officer be busy, peering downwards; consulting his map; afterwards scribbling hastily in his notebook. If he is not quite sure what anything is that he sees below him, he will ask the pilot to circle back, so that he can make another inspection. If the weather is perfectly clear, he may be able to instruct the airman to soar higher, and so be safer from any gun-fire from below. On the other hand, if the morning or evening is misty, he may have to take the risk of descending lower. Each unit on the squadron of observing aeroplanes will be carrying out the same routine. Wide-spread, the air-scouts will sweep over the enemy’s position. In an hour, each air-scout will be able to traverse a distance of more than fifty miles, and nothing of importance below him should pass undetected. In a little more than an hour, from the time of their starting away, the squadron of machines should be returning to their camp. One by one they will come gliding down, and the observation officer in each machine will present a written report to his immediate chief. This officer, when all these reports are in his possession, will seek the Commander of the aviation depot. These two officers will speedily sift out the information brought in by air-scouts, and prepare, for the consideration of the Commander-in-Chief, a summary of the whole reconnaissance. This the Commander of aeroplanes will take with him to Headquarters, and the Commander-in-Chief, with the members of his staff, will bend over their maps, tracing the enemy’s dispositions, noting his weak points, and also the positions where he may be in force. In regard to observing the actual movements of troops, as apart from the positions of stationary forces, the work of the war aeroplane should be wonderfully effective. An air-scout may, for example, report that a section of the enemy is on the march between two points at a given time. This news may be considered, by the Commander-in-Chief, to have a very important bearing upon the development of the enemy’s plan of campaign. Is this body of troops still moving in the same direction, say an hour later? This may, quite likely, be the question upon which the Commander-in-Chief may want information. Upon hearing this, the Commander of aeroplanes will soon have two or three scouting machines on the move. There will be no difficulty about such individual work as this; and very soon the Commander-in-Chief should be supplied with the news that he requires.