The present war has demonstrated that air-craft are the eyes of both armies and navies. If the Wright Brothers could have come to the country's aid in the Spanish War, the American fleet would not have remained in doubt outside Santiago Harbor. Before the advent of aviation, one of the chief desiderata to a commanding officer was to find out what the enemy was doing behind the hill. Without the aëroplane, it is impossible to prevent surprises in force, and to avoid the deadly ambuscade. The aëroplane is absolutely indispensable for the location of masked batteries. It is impossible, without aëroplanes, even to approximate the number and disposition of troops to which an army may be opposed. It is necessary to have not only a sufficient number of aëroplanes, especially designed and equipped for this purpose, but also other aëroplanes, armed and equipped, to co-operate with them, and defend them against attack from the aëroplanes of the enemy. Just as dreadnoughts require battle-cruisers, and both require torpedo-boat destroyers, and all require other scout-ships and submarines, for co-operation against a fleet of an enemy, so do dirigibles and the different types of aëroplanes, according to their purpose, require one another for concert of action. What we have already seen of battles fought in the sky leads us to surmise that aërial battles of the future will be fought on a much larger scale. It will be found that the commander who expects to conquer the ground held by an enemy must first conquer the sky. Aviation carries war into the third dimension. Not only must the advance or retirement of troops be supported by artillery thundering from hill to hill, but also the troops must be supported and guided by pilots in the sky. The last Congress appropriated $1,000,000 for the aviation purposes of the Navy. It is the same million dollars that was cut from last year's appropriation, which ought to have been expended for the purpose during that period.