202 THE LANGLEY AERODROME. 



took less strain than in the tirst case. A plate of ])rass woiohing 1 

 pound, for instance, was hung- from the end of the arm by a spring, 

 which was drawn out till it registered that pound weight when the arm 

 was still. When the arm was in motion, with the spring pulling the 

 plate after it, it might naturally be supposed that, as it was drawn 

 faster, the pull would be greater, but the contrary was observed, for 

 under these circumstances the spring contracted till it registered less 

 than an ounce. When the speed increased to that of a bird, the brass 

 plate seemed to float on the air, and not only this, but taking into con- 

 sideration both the strain and the velocity, it was found that absolutely 

 less power was spent to make the plate move fast than slow, a result 

 which seemed very extraordinary, since in all methods of land and 

 water transport a high speed costs much more power than a slow one 

 for the same distance. 



These experiments were continued for three years, with the general 

 conclusion that by simply moving any given weight of this form fast 

 enough in a horizontal path it was possible to sustain it with less than 

 one-twentieth of the power that Newton's rule called for. In particular 

 it was proved that if we could insure horizontal flight without friction, 

 about 200 pounds of such plates could be moved through the air at the 

 speed of an express train and sustained upon it, with the expenditure 

 of 1 horsepower, sustained, that is, without any gas to lighten the 

 weight, or by other means of flotation than the air over which it is 

 made to run, as a swift skater runs safely over thin ice, or a skipping 

 stone goes over water without sinking, till its speed is exhausted. 

 This was saying that, so far as power alone was concerned, mechanical 

 flight was theoretically possible with engines we could then build, since 

 I was satisfled that boilers and engines could be constructed to weigh 

 less than 20 pounds to the horsepower, and that 1 horsepower would, 

 in theorj^ at least, support nearly ten times that if the flight were hori- 

 zontal. Almost everything, it will be noticed, depends on this; for if 

 the flight is downward it will end at the ground, and if upward the 

 machine will be climbing an invisible hill, with the same or a greater 

 eflort than every bicycler experiences with a real one. Speed, then, 

 and this speed expended in a horizontal course, were the first two 

 requisites. This was not saying that a fl3"ing machine could be started 

 from the ground, guided into such flight in any direction, and brought 

 back to earth in safet3^ There was, then, something more than power 

 needed; that is, skill to use it, and the reader should notice the dis- 

 tinction. Hitherto it had always been supposed that it was wholly the 

 lack of mechanical power to fly which made mechanical flight impossible. 

 The first stage of the investigation had shown how nuich, or rather 

 how little, power was needed in theory for the horizontal flight of a 

 given weight, and the second stage, which was now to be entered upon, 

 was to sho.w tirst how to procure this power with as little weight as 



