THE INTKKNAI. WORK OF THE WIND. 3 



"Turkey Buzzard " (Cathartes aura) is so plenty around the environs of Washing' 

 ton that there is rarely a time when some of them may not be seen in the sky, 

 gliding in curves over some attractive point, or, more rarely, moving in nearly 

 straight lines on rigid wings, if there be a moderate wind. On the only occasion 

 when the motion of one near at hand could be studied in a very high wind, the 

 author was crossing the long " Aqueduct Bridge " over the Potomac, in an unusu- 

 ally violent November gale, the velocity of the wind being probably over 35 

 miles an hour. About one third of the distance from the right bank of the river, 

 and immediately over the right parapet of the bridge, at a height of not over 20 

 yards, was one of these buzzards, which, for some object which was not evident, 

 chose to keep over this spot, where the gale, undisturbed by any surface irregulari- 

 ties, swept directly up the river with unchecked violence. In this aerial torrent, 

 and apparently indifferent to it, the bird hung, gliding, in the usual manner of its 

 species, round and round, in a small oval curve, whose major axis (which seemed 

 toward the wind) was not longer than twice its height from the water. The bird 

 was therefore at all times in close view. It swung around repeatedly, rising and 

 falling slightly in its course, while keeping, as a whole, on one level, and over the 

 same place, moving with a slight swaying, both in front and lateral direction, but 

 in such an effortless way as suggested a lazy yielding 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 during 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. 



If the wiud is such a body as it is commonly supposed to be, it is absolutely 

 impossible that this sustentation could have taken place in a horizontal current any 

 more than in a calm, and yet that the ability to soar is, in some way, connected with 

 the presence of the wind, became to the writer as certain as any fact of observation 

 could be, and at first the difficulty of reconciling such facts (to him undoubted) 

 with accepted laws of motion, seemed quite insuperable. 



Light came to him through one of those accidents which are commonly found 

 to occur when the mind is intent on a particular subject, and looking everywhere 

 for a clue to its solution. 



In 1887, while engaged with the " whirling-table " in the open air at the Alle- 

 gheny Observatory, he had chosen a quiet afternoon for certain experiments, but in 



