GENE R A 1 
OBSERVATIONS 
0 N 
BIRDS. 
O Uadrupeds have feme diftant re-fern- 
b'iance, in their internal ftrudfure, with 
n wn, but that of Birds is entirely dif- 
fimilar j thefe animals feem wholly formed to in- 
habit the empty regions of air, in order that no 
part of nature may be left un tenanted. Their 
wings, which are their principal inftruments of 
hignt, are formed, for this purpofe, with the 
greateft exachnefs, and placed at that part. of 
tae;r body winch bed ferves to poize the whole, 
and fupport it m a fluid that at firft feems fo 
muen lighter than itlelf. The quills are at once 
Am and hollow, which gives them the advan- 
A 
