The first of these was the bird of prey of M. Santos Dumont. Rudely simple was it in its construction. Two box kites formed the supporting surface. In the centre was the motor, with the screw behind. To attain flight the machine was run upon wheels along the ground until a certain speed was reached, when the machine rose into the air. With this the inventor did not do much more than make aërial jumps; but rude as it was it contained one feature which has since been retained in all aëroplanes. In this one respect it was an advance--and a very necessary one--upon the Wright machine. That feature was the attachment of wheels to the machine that has been mentioned above. This was, indeed, an important step in the evolution of the aërial scout. Had it been necessary to continue using the external starting catapults that were a feature of the early experiments of the Wrights, the application of the aëroplane to warfare would have been somewhat limited. The well-known Voisin machine was another outcome of this period, but, imperfect as it was, it brought Mr. Henry Farman into fame, for on it he was the first man in Europe to fly any distance worthy of mention. THE FARMAN BIPLANE. Discontented with the Voisin machine, Mr. Henry Farman constructed one of his own design. Though it appeared at an early stage of aëroplane development, it still remains one of the most efficient types of biplanes. It has been used enormously in France, and armoured Farmans play an important part in the great war that is proceeding. Mr. Farman quickly realised that for maintaining lateral stability the vertical planes fitted between the main planes of the Voisin type were a very poor substitute for the wing-warping method of the brothers Wright. He, however, produced the movement of the main surfaces in an original manner. He hinged small flaps to the rear extremities of the main planes. These he called “ailerons.” They produce much the same effect as the wing-warping method of the brothers Wright. When the biplane tilted sideways, the flaps were drawn down on the side that was depressed. The pressure of the air on the flaps forced the aëroplane back on an even keel. In the normal condition the flaps flew out straight in the wind on a level with the main planes. Another noticeable feature of Mr. Farman’s machine was the production of the first light and efficient landing chassis. This was a combination of wooden skids and bicycle wheels. Below the biplane, on wooden uprights, he fitted two long wooden skids. On either side of each skid he placed two little pneumatic tyred bicycle wheels, connected by a short axle. These were held in position on the skid by stout rubber bands passing over the axle. In a general way the wheels raised the skids from the ground, but if the ascent was abrupt the wheels were forced against the rubber bands and the skids came in contact with the ground. With the abatement of the force of the shock the wheels came again into play.