Experts do not care to prophesy what will happen, say in the next great war, if flying machines fight in large numbers. That there will be such fighting is agreed; but what form it will take, and what damage the combatants will do each other, are problems time alone can solve. When the tactics of fighting aircraft are studied there is one point always to be remembered; and this is, that machines can steer not only to and fro and from side to side, but can also move up and down; and this introduces a confusion which does not exist in any other form of war. On the land, and upon the sea, two machines fighting must move always on the same plane; but in the air one may rise above the other, or dive swiftly below it, in addition to the manœuvres possible by wheeling and circling, and sweeping in suddenly to an attack. Mr. H. G. Wells, in his novel _The War in the Air_, considers that aerial battles will develop into a series of duels, fought between isolated machines. By this he means that, although a squadron of fighting craft may move into action in regular formation, the speed at which they are able to fly, and the fact that they can rise or descend, will soon scatter them in all directions; with the consequence that a couple of machines, singling each other out for combat, will wheel and circle away from the other craft and fight their duel alone. Such a scattered, indecisive form of fighting would undoubtedly take place to-day were aircraft called to meet in war, and for the reason that the machines forming a squadron would have no satisfactory means of communicating with each other. In a fleet of warships, when it fights, the discipline is perfect, and the signals from the flagship instantly obeyed. A number of units can in this way be made to fight as one. But in the air, until wireless telegraphy is applied with greater certainty, it will be difficult for a commander to guide the movements of his craft. Flag-signalling would be slow; the flags might not be seen. What would be needed is some almost instantaneous method of altering a battle position, or of turning and sweeping suddenly upon an enemy. An ideal communication, in the delivery of some swift blow, would be by wireless telephone. Then a Commander, taking up his instrument as he flew high above the contending craft, could speak an order in an easily-read code, which would make the vessels of his fleet turn swiftly and correctly upon any new course.