"Facing dead into the wind, and keeping the front edge of the supporting surfaces depressed, so that the wind shall blow upon their backs and press them downward, the operator first adjusts his apparatus and himself to the veering wind. He has to struggle to obtain a poise, and in a moment of relative steadiness he runs forward a few steps as as he may. and launches himself upon the breeze. by raising up the front edge of the sustaining surfaces, so as to receive the wind from beneath at a very small angle (2 to 4 degrees) of incidence. If the surfaces and wind be adequate, he finds himself thorough ly sustained, and then sails forward on a de scending or undulating course, under the com bined effects of gravity and of tke opposing wind. By shifting either his body or nis wings, or both, he can direct his descent, either side ways or up or down, within certain limits; lie can cause the apparatus to sweep upward so as to clear an obstacle, and lie is not infre quently lifted up several feet by a swelling of the wind. The course of the glide eventually brings the apparatus within a few feet of the ground (6 to 10 feet). when the operator, by throwing his weight baekward, or his wings for ward. if they be movable, causes the front of the supporting surfaces to tilt up to a greater angle of incidence, thus increasing the wind resistance, slowing the forward motion, and enabling him, by a slight oscillation, to drop to the ground as gently as if he had fallen only one or two feet." With the machine shown in the illustration Herr Lilienthal. starting from a height, was able to sail several hundred feet—the flight in some instances being against a wind of 24 miles per hour—and to make turns to the right or left with considerable certainty. Mr. Chanute's' ex periments were conducted first with a machine like Herr Lilienthal's but with one pair of wings only; seeond, with a machine having five pairs of wings, one above the other, and a sixth pair forming a tail; third, with a machine consisting of two wings., one above the other, and without
any break in the middle, as shown in the first of the two illustrations of his apparatus; and finally with a large bird-like structure of the form shown in the illustration. The greatest success, perhaps, must lie credited to the double winged machine, which made numerous flights, some of them against winds of from 10 to 31 miles per hour. The longest flight made was 359 feet. from a starting point 62 feet higher than the point of landing.
BIBLIOGRAPHY. As most of those who have Bibliography. As most of those who have carried on aeronautical experiments and have made systematic balloon ascents have been either scientiAc or military men, there is a valuable lit erature. Consult liattan Tumor, Astra Castro: Experiments and Adventures in the .atmosphere (London, 1865) ; T. Glashier. Voyages adriens (London, 1871) Tissandier, Les buttons diri gibles (Pari4, 1872) ; Coxwell, Ify Life and Bal loon Experiences (London, 1888) ; Pettigrew, Animal Locomotion (New York, 1872) ; S. P. La ngley, Aerodynamics and Internal Work of the Wind. Smithsonian Institution (Washington, 1891 ) ; 0. Chanute. Progress in Plying Machines; Proceedings of the International Conference an Aerial Navigation; The Aeronautical Annual (London, ; the Proceedings of the Aero nautical Society of Great Britain; the Balloon Sorirt y of Great Britain; Acath'mie d'Aerosta ion of France and the German Aeronautical Society. Among the periodicals devoted to ai3ro nauties. the hest known are: Zeitsch•ift fur Luft sehifffahrt and Physik der A tinoRphiire( Berlin) ; The A i'ronantieu/ Journal (London) : ILPero naute (Paris) ; L'Ai'•ophile (Paris) ; Revue de l'Ai'ronautique ( Pa ri,;