NATURAL HISTORY 
M4* 
furnished with a nictitating membrane, which is an ad- 
mirable provision, not only serving as a guard or cur- 
tain, but as an instrument to clear the eye of any in- 
cumbrance, and to lubricate it with a moisture which 
Nature has provided for the purpose. By these provi- 
sions, the sight of birds is rendered infinitely superior 
to that of all other animals; and this provision seemed 
the more necessary, from the peculiar modes of living 
to which this portion of created being was destined; 
A hawk will see a small bird at a distance, which neither 
men nor dogs could perceive; and a kite from an almost 
imperceptible height, will dart down on its prey with an 
unerring aim. 
Granivorous birds have their structure different from 
those of the rapacious kind. Their gullet dilates, form- 
ing itself into a crop. This is furnished w r ith salivial 
glands, whose office is, to moisten and soften the hard 
food on which they live, after which it passes on and is 
ground between two hard muscles, called the gizzard, 
whose action against each other is capable of attenuating 
the hardest substances; and, in order to assist this pro- 
v cess, birds pick up sand, gravel, and other hard sub- 
stances, which is necessary to mastication. 
To birds, the return of spring is the beginning of 
pleasure. Those vital spirits, which seemed locked up 
during the winter, then begin to revive. Vegetables and 
insects supply abundance of food, and birds, having 
more than sufficient for their own subsistence, are im- 
pelled to transfuse life as well as maintain it. Those 
warblings, which constitute the delightful concert of the 
grove, are in reality challenges of anger between the 
males, or calls of allurementTo the females. By these 
calls, the birds begin to pair, and provide for a future 
progeny. In our w r oods and our fields, we learn the les- 
son of inviolable fidelity: their compact holds with un- 
broken faith, and their tender solicitude for their young 
affords a noble example for the imitation of mankind. 
Birds are admirably fitted for flying; their wings serve 
as oars, and their tails as rudders, to direct their motions. 
It is by the largeness and strength of the pectoral mus- 
