44 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. €)2 



writer to follow as a necessary consequence, that there might be a 

 potentiality of what may be called * internal work ' " in the wind. 



" 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 pro1)able cause of the action of tlfe soaring 

 bird, it might be possible through its means to cause any suitably dis- 

 posed 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 realize the 

 exact mechanism by which this might be accomplished)." 



He then goes on with experiments made with extremely light and 

 sensitive anemometers to show that the apparently continuous flow of 

 a wind is in reality made up of an extreme contrariety of gusts, 

 capable, if they could be taken advantage of, not only of supporting 

 a body in air, but even of causing it to rise and advance against the 

 general direction of the wind. 



" 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 direction is opposed to the main cur- 

 rent, and to omit those which are not so, and thus without the expen- 

 diture of energy to construct a force which will act against the main 

 current itself. 



" But we may go materially further, and not only admit that it 

 is not necessary to invoke here, as Maxwell has done in the case of 

 thermodynamics, a being having a power and rapidity of action far 

 above ours, but that, in actual fact, a being of a lower order than 

 ourselves, guided only by instinct may so utilize these internal motions. 



" We might not indeed have conceived this possible, were it not 

 that nature has already, to a large extent, exhibited it before our eyes 

 in the soaring bird, which sustains itself endlessly in the air with nearly 



" Since the term " internal work " is often used in thermo-dynamics to signify 

 molecular action, it may be well to observe that it here refers not to molecular 

 movements, but to pulsations of sensible magnitude, always existing in the wind, 

 as will be shown later, and whose extent and extraordinary possible mechanical 

 importance it is the object of this research to illustrate. The term is so significant 

 of the author's meaning that he permits himself the use of it here, in spite of the 

 possible ambiguity. 



