AERIAL LOCOMOTION 



243 



which shaped itself in the form of a lemniscate, Fig. 170. 

 The figure 8 would exactly express what we saw, and 

 the resemblance was the more complete because, in the 

 trajectory thus described, one of the limbs seemed 



Fig. 170. — Appearance of a wasp flying in the sun. The extremity of the wing is 



gilded. 



larger and brighter than the other. In describing this 

 appearance we ignored, or omitted to mention the fact, 

 that Mr. Pettigrew, in England, had noticed the same 

 appearance in a flying insect, which gave rise on his 

 part to claims of priority of discovery. Nevertheless, 

 we may remark that the method of formation of the 

 figure described by 

 the wing of an insect, 

 according to Mr. 

 Pettigrew, is quite 



different IrOni OUr FlG< m._The trajectory of the anterior and po*- 



prmppntinn A ppnrrl- terior border of the wiD S of an ins ect during halt 

 Conception. .VCCOm- a n oscillation (Pettigrew> 



ing to the English 



authority, the anterior border of the wing describes one 

 limb of the lemniscate while the inferior border de- 

 scribes the other. In Fig. 171, which is borrowed from 

 his work, the arrows indicate a complete reversal of the 

 wing surface in a simple movement from left to right. 



