What the fleet commander wants to know is how those enemy vessels beyond the horizon, which may be within range of his guns tomorrow, the day after, or next week, may be distributed, and how many of them there are. This is where the speed of the airplane comes in. A machine which can travel 100 miles an hour covers a thousand miles in 10 hours. Locating an approaching enemy fleet this distance away, it brings back the news of the approach in 10 hours. It takes the fleet, traveling at 15 miles an hour, two days and 18 hours to cover this distance. The aeroplane can beat it by two days and eight hours. But the aeroplane flying high enough to give it the widest practical range of vision is able to see only over a path 75 miles wide under the most favorable weather conditions. Haze will cut this down considerably. This means that for anything like complete scouting work a fleet must be equipped with a large number of them. PROPORTION OF FIGHTING PLANES. Then, too, there must be a generous proportion of fighting planes to spread out in a very wide circle beyond the fleet. It will be appreciated that this circle must be a mighty wide one if the enemy planes be kept far enough away to prevent their counting the number and type of ships in the command. There is required also a large detail to guard against the submarines. While an aeroplane can see quite deep in the sea, this penetrating vision is limited to the water directly beneath it. It can see straight down in the water, but not off to the side at an angle. If such a thing is possible, air control at sea is more important than over the land, and of first value is the fighting plane. In this connection there is an aeroplane gun which works well. It is a double-ender. That is, there is a breech in the middle, and the two ends are muzzles. In air fighting it is seconds and fractions of seconds that count, and the advantage of this gun lies in that it can be fired in opposite directions, thus cutting down the length of the arc through which it has to be swung to be brought to bear on the enemy. Of exceptional value to the United States navy is the super-American type of planes which the Curtiss factories have developed and which have done such wonderful service for the British. In this type the fuselage is entirely enclosed, built with a hull much along the lines of the motorboat or hydroplane. The 'plane may thus come to rest safely in the open sea. It weighs nearly 6000 pounds and can carry a useful load of more than 2000 pounds. The boat is slung well below the planes, eight feet below the lower one, which has a span of 66 feet. Eight feet above this is the upper plane, which overlaps the lower plane by 13 feet on each side. The complete span of the upper plane is 92 feet. It can carry six to eight men, if necessary, altogether a huge, sturdy, dependable machine with two powerful motors. And what was done to give America the equipment of 'planes which we needed?