THE TRIUIVIPH OF THE AEROPLANE 



fellow-countryman was wrong. For years he had made 

 a study of the jflight of birds, and his studies had led 

 him to the same conclusions that have usually been 

 reached by every student of the subject, both before 

 and since — that soaring flight, without any flapping 

 movement, is possible under certain conditions; that 

 curved surfaces can acquire a horizontal motion by 

 the action of the wind alone, "when their curvature 

 bears a certain relation to their superficies '* — in short, 

 a relation represented exactly by the wings of birds. 



It was not supposed by Lilienthal, or by any of the 

 members of the school of aviators, that simply by 

 making a device that reproduced the proportions and 

 shape of a bird any person might mount and fly. But 

 it was believed that, given such a device, a man might 

 learn to fly with practice. Lilienthal, therefore, con- 

 structed a flying-machine with correctly curved surfaces 

 made of linen stretched over a light wooden frame, the 

 total area being about fourteen square yards, and the 

 whole machine weighing only about forty pounds. In 

 the center was an aperture where the operator was 

 stationed, holding the frame in position by his arms. 

 Obviously, as no flapping motion in imitation of a 

 bird*s wings was possible, some other means of giving 

 the necessary impetus for horizontal flight was necessary, 

 and here again the study of birds suggested a method. 



It is a well-known fact that certain soaring birds can- 

 not leave the ground when once they have alighted, ex- 

 cept by an initial run to acquire the necessary speed ; and 

 every goose hunter is familiar with the manner in which 

 these birds run along the surface of water, flapping their 



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