MECHANISM OF INSECT FLIGHT. 199 



on the contrary, the air will be drawn forwards, so that the 

 flame of another candle placed in front of the nerviire will be 

 strongly drawn towards it. 



Fig. 84. — Artificial representation of the movements of an insect's wing. 



3. Of the propulsive action of the wings of insects. — In the 

 same manner as the squib moves in the opposite direction to 

 the jet of flame which it throws out, the insect propels itself 

 in the course opposed to the current of air produced by the 

 movement of its wings. 



Each stroke of the wing acts on the air obliquely, and 

 neutralizes its resistance, so that a horizontal force results, 



