THE LANGLEY AERODROME. 201 



without an}- niotion of its wino-.^, as though it needed no work to sustain it, 

 but was kept up there b}' some miracle. But, however sustained, I saw 

 it sweep, in a few seconds of its leisurely flight, over a distance that to me 

 was encumbered with ever}- sort of obstacle, which did not exist for it. 

 The wall over which I had climbed when I left the road, the ravine I 

 had crossed, the patch of undergrowth through which I had pushed 

 my wa}-— all these were nothing to the bird, and while the road had 

 only taken me in one direction, the bird's level highway led everv- 

 where, and opened the way into every nook and corner of the land- 

 scape. How wonderfully easy, too, was its flight! There was not a 

 flutter of its pinions as it swept over the field, in a motion which 

 seemed as eflortless as that of its shadow. 



After many years and in mature life, I was brought to think of 

 these things again, and to ask myself whether the problem of artificial 

 flight was as hopeless and as absurd as it was then thought to be. 

 Nature had solved it, and wh}^ not man ? Perhaps it was because he 

 had begun at the wrong end, and attempted to construct machines to 

 fly before knowing the principles on which flight rested. I turned for 

 these principles to my books and got no help. Sir Isaac Newton had 

 indicated a rule for finding the resistance to advance through the air, 

 which seemed, if correct, to call for enormous mechanical power, and 

 a distinguished French mathematician had given a formula showing 

 how rapidl}- the power must increase with the velocity of flight, and 

 according to which a swallow, to attain a speed it is now known to 

 reach, must be possessed of the strength of a man. 



Kemembering the eflortless flight of the soaring bird, it seemed that 

 the first thing to do was to discard rules which led to such results, and 

 to commence new experiments, not to build a flying machine at once, 

 but to find the principles upon which one should be built; to find, for 

 instance, with certaint}^ by direct trial how much horsepower was 

 needed to sustain a surface of given weight by means of its motion 

 through the air. 



Having decided to look for myself at these questions, and at first 

 hand, the apparatus for this preliminary investigation was installed at 

 Allegheny, Pa., about ten years ago. It consisted of a "whirling 

 table" of unprecedented size, mounted in the open air, and driven 

 round by a steam engine, so that the end of its revolving arm swept 

 through a circumference of 200 feet, at all speeds up to 70 miles an 

 hour. At the end of this arm was placed the appai-atus to be tested, 

 and, among other things, this included surfaces disposed like wings, 

 which were hung from the end of the arm and dragged through the 

 air till its resistance supported them as a kite is supported by the wind. 

 One of the first things observed was that if it took a certain strain to 

 sustain a properly disposed weight while it was stationary in the air, 

 then not only to suspend it but to advance it rapidly at the same time 



