PART III. 



APPLICATION. 



Of these irregular movements of the wind, which take place up, down, and on 

 every side, and are accompanied of necessity by equally complex condensations and 

 expansions, it will be observed that only a small portion, namely, those which occur 

 in a narrow current whose direction is horizontal and sensibly linear, and whose 

 width is only the diameter of the anemometer, can be noted by the instruments I 

 have here described, and whose records alone are represented in the diagrams. 

 However complex the movement may appear as shown by the diagram, it is then 

 far less so than the reality, and it is probable, indeed, that anything like a fairly 

 complete graphical representation of the case is impossible. 



I think that on considering these striking curves (Plates I., II., III., IV., and 

 V.) we shall not find it difficult to admit, at least as an abstract conception, that 

 there is no necessary violation of the priuciple of the conservation of energy im- 

 plied in the admission that a body, wholly immersed in and moving with such a wind, 

 may derive from it a force which may be utilized in lifting the body, in a way in 

 which a body immersed in the " wind " of our ordinary conception could not be 

 lifted, and if we admit that the body may be lifted, it follows obviously that it 

 may descend under the action of gravity from the elevated position, on a sloping 

 path, to some distance in a direction opposed to that of the wind which lifted it, 

 though it is not obvious what this distance is. 



We may admit all this, because we now see (I repeat) that the apparent viola- 

 tion of law arises from a tacit assumption which we, in common with all others, may 

 have made, that the wind is an approximately homogeneously moving body, because 

 moving as a whole in one direction. It is, on the contrary, always, as we see here, 

 filled (even if we consider only movements in some one horizontal plane) with 

 amazingly complex motions, some of which, if not in direct opposition to the main 

 movement, are relatively so, that is, are slower, while others are faster than this 

 main movement, so that a portion is always opposed to it. 



From this, then, we may now at least see that it is plainly within the capacity 

 of an intelligence like that suggested by Maxwell, and which Lord Kelvin has 

 called the " Sorting Demon," to pick out from the internal motions those whose 



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