4 THE inti:i:\ai. work of the wind. 



the absence of the entire calm which is almost never realized, had placed one of 

 the very small and light anemometers made for hospital use, in the open air, with 

 the object of detenu in ing and allowing for the velocity of what feeble breeze 

 existed. His attention was called to the extreme irregularity of this register, and 

 he assumed at first thai the day was more unfavorable than he had supposed. Sub- 

 sequent observations, however, showed that when the anemometer was sufficiently 

 light and devoid of inertia, the register always showed great irregularity, especially 

 when its movements were noted, not from minute to minute, but from second to 

 second. 



His attention once aroused to these anomalies, he was led to reflect upon 

 their extraordinary importance in a possible mechanical application. He then de- 

 signed certain special apparatus hereafter described, and made observations with 

 it which showed that " wind " in general was not what it is commonly assumed to 

 be, that is, air put in motion with an approximately uniform velocity in the same 

 strata : but that, considered in the narrowest practicable sections, wind was always 

 not only not approximately uniform, but variable and irregular in its movements 

 beyond anything which had been anticipated, so that it seemed probable that the 

 very smallest part observable could not be treated as approximately homogeneous, 

 but that even here, there was an internal motion to be considered, distinct both 

 from that of the whole body, and from its immediate surroundings. It seemed to 

 the 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 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 realize the exact mechanism 1>\ which this might be accomplished). 



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



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

 action, it may he well to observe that it here refers not to mold ular 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. 



