We shall, no doubt, have occasion to return later to the heroic achievements of our airmen in destroying enemy raiders. Meanwhile, our attention is claimed by a subject of great interest and importance, namely, the part played by aircraft on the various battle fronts of the great war. It was clear some while before the outbreak of hostilities that the aeroplane was destined to play a prominent part. Mr. Sydney F. Walker, R.N., M.I.E.E., remarks, in a useful little volume on aviation, published before the war, that the first important work to which the aeroplane has been put is that of scouting. ‘When armies are manœuvring in the field, it is the great object of each general to find out what his opponent is doing, exactly where his forces are, where each particular arm is weak, and where, above all things, he is open to attack. On the other hand, each general makes the greatest efforts to prevent his opponents from finding out all about himself. The art of hiding men, and even of artillery and of horses, has been brought to such success that the non-military observer might be in the midst of an army of 30,000 or 40,000 men and be perfectly ignorant of their presence. Every inequality in the ground, every natural object, such as a tree, a mound, a house, &c., is made use of for the purpose of concealing the presence of men, horses, and accessories. It will be evident that with an aeroplane flying at anywhere up to eighty miles an hour, and that has been exceeded at the time of writing, and viewing the surface of the ground from above—provided the pilots, or passengers accompanying them, are trained to observe the ground and the bodies of men on the ground from above—practically any disposition of the enemy could be discovered.’