142 THE FLIGHT OF BIRDS 
with his wings. He gets the wind to lift him, and 
as he rises he circles#6r, more correctly, describes 
a spiral or helix. It is a marvellous performance. 
Had we not an unlimited capacity for getting used 
to anything, we should be lost in wonder whenever 
we see this splendid achievement. 
Many of the larger birds are proficient at it— 
Eagles, Vultures, Pelicans, Storks, Falcons, Kites, 
Buzzards, Ravens, Gulls and others, all, even the 
smallest of them, possessed of wings that have a 
very considerable area, and are very different in 
outline from the long, narrow wings of the Tern or 
the Swift. The Gull’s wing is less definitely a soaring 
wing than the others mentioned ; adapted both for 
soaring and long-distance flapping flight, it is a 
compromise between the broad and the narrow.* 
Evidently breadth, and not only length, is im- 
portant in soaring, and the great primary feathers 
spread out, leaving very noticeable gaps between 
them. Probably this gives steadiness, preventing 
a too sudden escape of air from under one wing. If 
a bird is watched through a field-glass or telescope, 
the upward bending of these great feathers by the 
force of the wind is sometimes quite noticeable, the 
first primary being often bent considerably more 
than the others (see the Frontispiece). 
It is a slow, sedate movement, this circling high in 
air. Mr. 8. E. Peal,t+ who used to gaze with wonder 
at the circling of the Adjutants, a kind of Stork noted 
for their soaring, over the plain of Upper Assam, 
held, if I remember rightly, that the birds slept as 
* See Pl. xiv. 
ft See Nature, Nov. 4, 1880; Sept. 26, 1889; May 21, 1891. 
