Another craft, designed for scouting operations, may be likened to the mosquito craft of the seas. This machine, while a biplane like the military aeroplane, is of lighter construction, everything being sacrificed to speed in this instance. It is fitted with a 100 horse-power motor and is designed to carry an observer if required. There is no offensive armament, however. The fuel tank capacity, moreover, is limited, being only sufficient for a two or three hours' flight. While this is adequate for general reconnoitring, which for the most part entails short high speed flights, there are occasions when the Staff demands more prolonged observations conducted over a greater radius. This requisition can be met by eliminating the observer, whose duties in this instance must be assumed by the pilot, and substituting in place of the former, a second fuel tank of sufficient capacity for a flight of four or five hours, thereby bringing the term of action in the air to about 6 1/4 hours. This machine travels at a very high speed and is eminently adapted to its specific duty, but it is of limited service for general purposes. The arming of an aeroplane, to enable it to defend itself against hostile attack or to participate in raiding operations upon the aerial fleet of the enemy, appears to be a simple task, but as a matter of fact it is an undertaking beset with difficulties innumerable. This is especially the case where the aeroplane is of the tractive type, that is to say where the propellers are placed in the forefront of the machine and in their revolution serve to draw the machine forward. All other considerations must necessarily be sacrificed to the mounting of the propeller. Consequently it is by no means easy to allot a position for the installation of a gun, or if such should be found there is grave risk of the angle of fire being severely restricted. In fact, in many instances the mounting of a gun is out of the question: it becomes a greater menace to the machine than to the enemy. The French aeronautical section of the military department devoted considerable study to this subject, but found the problem almost insurmount able. Monsieur Loiseau met with the greatest measure of success, and his system is being practised in the present campaign. This principle is essentially adapted to tractor aeroplanes. Forward of the pilot a special position is reserved for the gunner. A special mounting is provided towards the prow, and upon the upper face of the body of the machine. The gun mounting is disposed in such a manner that it is able to command a wide arc of fire in the vertical plane over the nose of the machine and more particularly in the downward direction.