NO. 8 SAiMUEL PIERPONT LAN(;LEY ABBOT 



43 



lateral direction but in such an effortless way as suggested a lazy yield- 

 ing of itself to the rocking of some invisible wave. 



" It may be asserted that there was not only no flap of the wing, 

 but not the quiver of a wing feather visible to the closest scrutiny, 

 during the considerable time the bird was under observation, and dur- 

 ing which the gale continued. A record of this time was not kept, but 

 it at any rate lasted until the writer, chilled by the cold blast, gave up 

 watching and moved away, leaving the bird still floating, about at 

 the same height in the torrent of air, in nearly the same circle, and 

 with the same aspect of indolent repose. 



" Light came to him through one of those accidents which are 

 commonly found to occur when the mind is intent on a particular sub- 

 ject, and looking everywhere for a clue to its solution. 



" In 1887, while engaged with the * whirling-table ' in the open 

 air at the Allegheny Observatory, he had chosen a quiet afternoon for 

 certain experiments, but in 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 determining 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 that the day was more unfavorable 

 than he had supposed. Subsequent 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 applica- 

 tion. He then designed 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 

 S 



