INTRODUCTION. 
Ixxix 
most rapidly, most increase their speed. The Jay, the Owl, and the Mag- 
pie, hap their wings nearly close round their bodies, and slowly, and, by this 
action, lose the advantage of their extension ; — the Gull, which appears 
to be a bird of moderate powers of wing, makes a less angle in its mo- 
tions ; but the movement of the wing of the Kingfisher can scarcely be 
perceived, by the most acute power of vision, to fall beneath an horizontal 
line. Many birds, in their flight, use strange contortions, as the Goatsucker 
and some of the Pigeon tribes, which frequently clash their wdngs together, 
making a loud noise from their collision; others, as the Wood-pigeon, 
whose firm pinions stoutly lash the air, raise a great sound in flight ; the 
Partridge and the Woodcock create, by the impulse of their wings, a loud, 
whirring buzz ; but the Owl skims along in irregular curves, with softened 
strokes, scarcely occasioning the slightest noise by their percussion. Some 
quit the ground nearly in an horizontal line, as most of the Sparrow tribes ; 
a few with a spiral flight, like the Bittern ; others mount almost perpendi- 
cularly towards the sky, like the Lark and the Woodcock ; some descend 
gradually, and others by a sudden jerk, like the Water-rail, with their 
wings placed almost erect ; the Swift, on account of the length of its 
wings, and shortness of its legs, can only rise from the earth with the 
greatest exertion, it throws itself nearly on one side, and then, by a violent 
agitation of its upper wdng, and by pressing its under foot against the 
ground, it at length ascends. The Goatsucker quits the place on which it 
rests by first violently clashing its wings together over its back, and, receiv- 
ing the force of the impulse from the return of its pinions, springs into 
the air. Almost all birds slightly unfold their tails in flight, to render the 
in a bird occupies no more than triple the space. The Goatsucker, with wide-spread wings and 
tail, covers an expansion, or is supported by a column of air upwards of two hundred super- 
ficial inches, and yet its body is but six inches long, and scarcely three ounces in weight; on the 
other hand, the Rabbit, that weighs four pounds, occupies, by the surface of its body, not exceed- 
ing one hundred superficial inches ; and, consequently, according to the well-known law of 
hydrostatics, the quadruped must sink in a medium, in which the bird might be supported 
with ease. 
