The rapidity with which an aeroplane onslaught can be made should, indeed, prove one of the most important features of aerial warfare. Destructive machines may fly from their Headquarters, deliver an attack fifty or a hundred miles away, and—their ammunition exhausted—return quickly to their base for more, and so be ready to renew the attack. II. Effect of aerial bombardment upon cities and troops—German tests. It was after a seven years’ study of military aviation, as Commandant of the British Government Balloon School, that Colonel J. E. Capper declared emphatically: "The necessity has arisen for every warlike nation to have a sufficient aerial fleet, armed and equipped for offensive warfare." His advice, however, was not adopted—at any rate, not by the War Office. No steps have yet been taken to estimate the value of an aeroplane as a destructive instrument, despite the fact that France and Germany are keenly alive to the possibilities of a large number of weight-carrying machines. In Germany, at the present time, secret tests and experiments are being made, and the construction of special machines undertaken. Meanwhile, we fumble along. If a war broke out to-morrow, it is true that destructive work by aeroplanes, on anything like a large scale, would not be undertaken. But what about the day after to-morrow—or rather next year? Every day, the general efficiency of the aeroplane is being improved, and its radius of action increased. Practically every day, also, foreign nations are adding to their air-fleets. Already the art of employing aircraft in fairly large numbers has been learned. Machines for destructive work can now be built—and are being built; and yet we are content, as yet, to do nothing. Sufficient warning has been given. Colonel Templer, an officer identified with the first Government aeronautical work undertaken in England, has declared: "It is conclusively proved that the aeroplane is a machine for carrying out attacks in warfare. We must, therefore, be prepared not only for defence against bomb-dropping aeroplanes; we must be prepared, if necessary, to use them." Another military expert of high repute, speaking of the havoc that a hostile air-fleet might work, by an attack upon the Thames Valley between Hammersmith and Gravesend, has observed: "This whole fifty miles of concentrated essence of Empire lies at the absolute mercy of an aerial machine, which could plant a dozen incendiary missiles in certain pre-selected spots." The point to be considered, in this connection, is this: such an aerial attack is no longer a vague possibility. It was only the other day, while discussing the destructive capabilities of modern-type aeroplanes, that a famous constructer showed how—if a large fleet of machines was marshalled together—it would be possible for an enemy to drop a couple of hundred tons of explosive matter upon London, suddenly appearing from across the Channel by air, and as flying quickly back again.