THE CONQUEST OF TIME AND SPACE 



miles an hour on the track had been acquired, the ap- 

 paratus lifted itself in the air, and sailed for some dis- 

 tance, a maximum flight of over three hundred feet 

 finally being made. This experiment demonstrated 

 several important things — ^in fact, solved "three out of 

 five divisions of the problem of flight," as Lord 

 Kelvin declared. It demonstrated that a flying-machine 

 carrying its own propelling power could be made power- 

 ful and light enough to lift itself in the air; that an 

 aeroplane will lift much more than a balloon of equal 

 weight; and that a well-made screw-propeller will 

 grip the air sufficiently to propel a machine at a high 

 rate of speed. 



Since the two remaining divisions of the five con- 

 cerned in the problem of flight had been already solved 

 by Lilienthal, it seemed that it only remained for some 

 scientist to combine this complete knowledge in the 

 proper way to produce a practical flying-machine — 

 one that would fly through the air, and continue to fly 

 until the power was exhausted. It was not a start- 

 ling announcement to the scientific world, therefore, 

 when about three years later the news was flashed that 

 Prof. S. P. Langley had produced such an apparatus. 



Professor Langley described this really wonderful 

 machine, which he called the "aerodrome," as follows: 



"In the completed form there are two pairs of wings, 

 each slightly curved, each attached to a long steel rod 

 which supports them both, and from which depends the 

 body of the machine, in which are the boilers, the en- 

 gines, the machinery, and the propeller wheels, these 

 latter being not in the position of an ocean steamer, but 



[284] 



