5 6 
BIRD-FLYING. 
The wings of a bird are its parachutes; and the move¬ 
ments of its wings the fall of the parachute, but lifted as 
faft as they fall; and as the refiftance occafloned by the 
fall (wing motions) augments with the fquare of the velo¬ 
city j the wings have this in their favour. 
And although the heavieft bird that flies is, for its 
protection and fafety, gifted like the infeCt with the power 
of riflng in ftill or forcelefs air from the furface of the 
ground, or from the face of the waters, its home, never- 
thelefs, is in the air, where its neft is among mountain 
peaks, or inacceflible hill-fldes, or on the tops of trees, in 
the fpires of churches ; or under the eaves of houfes, from 
whence the creatures launch themfelves, and on their para¬ 
chute wings fail and {kim through the air by a projeCtile- 
force flotation due to their weight employed as force. 
Pettigrew fpeaking to this, fays: “ The flying animal 
receives fupport from the air by increaflng the flze of its 
travelling furfaces. * * * When an infeCt, a bat, or a 
bird is launched in fpace, its weight (from the tendency of 
all bodies to fall vertically downwards) prefles upon the 
inclined planes or kites formed by the wings, in fuch a 
manner as to become converted direCtly into a propelling , 
and indiredly into a buoying , or fupporting power.” (See 
Pettigrew’s £< Animal Locomotion.”) If, inftead of infeEi , 
Pettigrew had faid butterfly , he would have been more 
correCt. 
Any one who watches birds, efpecially large ones, will 
