286 DISCOVERY CH. 



rubber band, the machine thus utilising motive energy 

 which it carried with it. 



Experiments with man-carrying machines were made 

 about 1889 by Otto Lilienthal in Germany, Percy 

 Pilcher in Scotland, and Octave Chanute in the United 

 States. These machines were, however, only gliders, 

 by means of which the experimenters could soar in the 

 air for a hundred yards or so, after taking a short run 

 against the wind, along the top of a hill or mound. In 

 none of these cases was a motor used successfully to 

 drive the wings of the aeroplane against the air and thus 

 maintain it from falling. Sir Hiram Maxim built in 1894 

 a huge machine driven by a steam engine, and proved 

 by it that the whole weight could be lifted slightly 

 off the rails on which the machine ran by driving the 

 planes against the air with sufficient velocity. A little 

 later M. Ader, in France, traversed a distance of about 

 fifty yards in his " Avion " aeroplane. 



All these machines may be 'not inappropriately 

 classified as devices of engineers to achieve flight by 

 invention call it practical experiment if you will- 

 before the principles of dynamic motion had been studied. 

 The practical man makes his machine first and lets 

 experience decide whether its design is sound or not ; 

 the scientific man begins by investigating the principles 

 involved in the problem, and then suggests how they 

 may be met. The only satisfactory way to determine 

 such principles is by experiment and calculations based 

 upon the results. The possibilities of artificial flight 

 were studied experimentally by a man of science at a 

 time when anyone who gave attention to the subject 

 received nothing but derision for his pains. Modern 

 aviation was based upon the results he obtained, for 

 he himself first showed that a system of planes could 



