THE INTERNAL WORK OF THE WIND. 5 



ties 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 assump- 

 tion made by nearly all writers, that the word " wind " means something so simple, 

 so readily intelligible, and so commonly understood, as to require no special defini- 

 tion ; 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 theo- 

 retical 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 quantita- 

 tively its amount by the use of special apparatus, recording the changes which go 

 on (so to speak) within the wind at very brief intervals. These results may, it is 

 hoped, be of interest to meteorologists, but they are given here with special refer- 

 ence to their important bearing on the future of what the writer has ventured to 

 call the science of Aerodromics.* 



The observations which are first given were made in 1887 at Allegheny, and 

 are supplemented by others made at Washington in the present year.f 



What has just been said about their possible importance will perhaps seem 

 justified, if it is remarked (in anticipation of what follows later) that the result of 

 the preseut discussion implies not only the theoretical, but the mechanical possi- 

 bility, that a heavy body, wholly immersed in the air and sustained by it, may, 



* From aepodpn/.taco, to traverse the air ; aspodpoj-W?, an air-runner. 



f It will be noticed that the fact of observation here is not so much the movement of cur- 

 rents, such as the writer has since learned was suggested by Lord Rayleigh so long ago as 1883, 

 still less of the movement of distinct currents at a considerable distance above the earth's surface, 

 but of what must be rather called the effect of the irregularities and pulsations of any ordinary 

 wind within the immediate field of examination, however narrow. 



See the instructive article by Lord Rayleigh in Nature, April 5, 1883. Lord Rayleigh remarks 

 that continued soaring implies : "(1) that the course is not horizontal ; (2) that the wind is not 

 horizontal ; or (3) that the wind is not uniform." " It is probable," he says. " that the truth is 

 usually represented by (1) or (2) ; but the question I wish to raise is whether the cause suggested 

 by (3) ma y not sometimes come into operation." 



