248 



MOVEMENT 



We succeeded in obtaining a photograph of the 

 gilded wing of an insect, which, though not absolutely 

 at liberty, could fly at a comparatively high rate of speed. 



Photography of the Trajectory of the Wing. — The 

 following is the arrangement we adopted for our experi- 

 ments. A wooden box one metre square and 025 



Fig. 174. — Insect flying round and round in front of a dark background. 



metre deep, was lined throughout with black velvet. 

 At the bottom of the box a central disc, supported by 

 a footpiece, was placed in position : the periphery of 

 the space was covered with a white material, leaving 

 between it and the central disc an annular track covered 

 with black velvet (Fig. 174). It was round this annular 



