S. P. Langley — Internal Work of the Wind. 45 



On further study, it seemed to him that this internal work 

 might conceivably be so utilized as to furnish a power which 

 should not only keep an inert body from falling, but cause it to 

 rise,, and that while this power was the probable cause of the 

 action of the soaring bird, it might be possible through its means 

 to cause any suitably disposed body, animate or inanimate, wholly 

 immersed in the wind, and wholly free to move, to advance 

 against the direction of the wind itself. By this it is not 

 meant that the writer then devised means for doing this, but 

 that he then attained the conviction both that such an action 

 involved no contradiction of the laws of motion, and that it 

 was mechanically possible (however difficult it might be to 

 to realize the exact mechanism, by which this might be 

 accomplished). 



It will be observed that in what has preceded, it is intimated 

 that the difficulties in the way of regarding this even in the 

 light of a theoretical possibility, may have proceeded, with 

 others as with the writer, not from erroneous reasoning, but 

 from an error, in the premises, entering insidiously in the 

 form of the tacit assumption made by nearly all writers, that 

 the word " wind" means something so simple, so readily intel- 

 ligible, and so commonly understood, as to require no special 

 definition ; while, nevertheless, the observations which are 

 presently to be given, show that it is, on the contrary, to be 

 considered as a generic name for a series of infinitely complex 

 and little known phenomena. 



Without determining here whether any mechanism can be 

 actually devised which shall draw from the wind the power 

 to cause a body wholly immersed in it to go against the wind, 

 the reader's consideration is now first invited to the evidence 

 that there is no contradiction to the known laws of motion, 

 and at any rate no theoretical impossibility in the conception 

 of such a mechanism, if it is admitted that the wind is not 

 what it has been ordinarily taken to be, but what the following 

 observations show that it is. 



What immediately follows is an account of evidence of the 

 complex nature of the " wind," of its internal movements, of 

 the resulting potentiality of this internal work, and of attempts 

 which the writer has made to determine quantitatively its 

 amount by the use of special apparatus, recording the changes 

 which go on (so to speak) within the wind in very brief 

 intervals. These results may, it is hoped, be of interest to 

 meteorologists, but they are given here with special reference 

 to their important bearing on the future of what the writer 

 has ventured to call the science of Aerodromics.* 



*From uepodpo/ueu, to traverse the air ; depodpofioc, an air-runner. 



