144 



ANIMAL LOCOMOTION. 



the wing of the bat and bird. The principle is, however, in 

 both cases the same, the loops ultimately terminating in a 

 waved track. The impulse is communicated to the insect 

 wing at the heavy parts of the loops ahcdefghijhlmn 

 of fig. 71 ; the waved tracks being indicated atj? 5 ^ of 

 the same figure. The recoil obtained from the air is repre- 

 sented at corresponding letters of fig. 72, the body of the 



Fig. n. 



Fig. 73. 



insect being carried along the curve indicated by the dotted 

 line. The impulse is communicated to the wing of the bat 

 and bird at the heavy part of the loops a b c d e f g h ij hlmno 

 of fig. 73, the waved track being indicated p s t u v w oi 

 this figure. When the horizontal speed attained is high, the 

 wing is successively and rapidly brought into contact with 

 innumerable columns of undisturbed air. It, consequently, is 

 a matter of indifference whether the wing is carried at a high 

 speed against undisturbed air, or whether it operates upon air 



