NATURAL HISTORY. 
PART II. 
BIRDS. 
THEIR GENERAL NATURE. 
HILE the forefts, the waters, and even 
vv the deaths of the earth, have their 
refpeftive inhabitants, the air, which in- 
cludes an immenfe fpace, too elevated for 
the power of man to explore, is traverfed 
by innumerable beings, of variegated beauty, 
called birds ; which, in order to facilitate 
their flight through thole expanfive regions, 
with a fwiftnefs to compenfate their want of 
ftrength, are formed on the following gene- 
ral principles. 
Form . — The body of a bird, is made lliarp 
in front, and, when on flight through its 
native element, it fwells gradually, until the 
toil is fully expanded, which, with the aid 
of 
