Mr. R. A. Proctor discusses the matter with his usual clear-sightedness. He premises that the bird may, in actual fact, only poise itself for some ten minutes--an interval which many will consider far too small--without flap of the wings, and, while contending that the problem must be simply a mechanical one, is ready to admit that "the sustaining power of the air on bodies of a particular form travelling swiftly through it may be much greater or very different in character from what is supposed." In his opinion, it is a fact that a flat body travelling swiftly and horizontally will sink towards the ground much more slowly than a similar body moving similarly but with less speed. In proof of this he gives the homely illustration of a flat stone caused to make "ducks and drakes." Thus he contends that the bird accomplishes its floating feat simply by occasional powerful propulsive efforts, combined with perfect balance. From which he deduces the corollary that "if ever the art of flying, or rather of making flying machines, is attained by man, it will be by combining rapid motion with the power of perfect balancing." It will now appear as a natural and certain consequence that a feature to be introduced by experimentalists into flying machines should be the "Aeroplane," or, in other words, a plane which, at a desired angle, should be driven at speed through the air. Most notable attempts with this expedient were now shortly made by Hiram Maxim, Langley, and others. But, contemporaneously with these attempts, certain feats with the rival aerostat--the balloon--were accomplished, which will be most fittingly told in this place. CHAPTER XX. A CHAPTER OF ACCIDENTS. It will have been gathered from what has been already stated that the balloonist is commonly in much uncertainty as to his precise course when he is above the clouds, or when unable from darkness to see the earth beneath him. With a view of overcoming this disadvantage some original experiments were suggested by a distinguished officer, who during the seventies had begun to interest himself in aeronautics.