236 FACULTIES OF BIRDS. 
In consequence of therapidity with which birds 
traverse the air, extent and acuteness of vision ap- 
pear to be indispensable, in order to direct them in 
their flight. Had they, indeed, been formed with 
eyes like the mole (Tolpa lucida, C. Bonaparte), 
incapable of seeing more than a few inches’ dis- 
tance, they would have been in constant danger of 
dashing against every intervening obstacle. “ In- 
deed,” says Buffon, “ we may consider the celerity 
with which an animal moves as a just indication of 
the perfection of its vision. A bird, for instance, 
that shoots swiftly through the air, must undoubt- 
edly see better than one which slowly describes 
a tortuous tract. Among quadrupeds, again, the 
sloths have avery limited sight.” It may accord- 
ingly be inferred, that birds have more precise ideas 
than slow-moving caterpillars, of motion and its ac- 
companying circumstances, such as those of rela- 
tive velocity, extent of country, the proportional 
height of eminences, and the various inequalities 
of hill and dale, mountaip and valley. 
The eye of birds, it is ‘Worthy of remark, besides 
being peculiar in structure, is also greatly larger 
than in most other animals in proportion to the 
bulk of the head. 
The mere bulk of the eye, however, is rather a 
fallacious test to trust to; for several birds, in 
which the globe of the eye is large, have very weak 
sight, particularly in the daytime, such as the wood- 
cock and the owls. -The woodcock (Scolopaxr Gal- 
linago, Ray) has very large, prominent eyes, but 
it cannot support a strong light, and sees best du- 
ring twilight; and, as Colonel Montagu remarks, its 
eyes seem to be peculiarly calculated for collect- 
ing the faint rays of light in the darkened vales and 
sequestered woodlands during nocturnal excursions, 
thus enabling it to avoid trees and other obstacles. 
It is probable, indeed, that the proverbial stupidity 
of the bird arises from this weakness of sight. 
