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MOVEMENT 



contrast. We were not very successful in our experi- 

 ments with all kinds of insects ; the method, it is 

 true, allows of the insect being posed at will, and also 

 allows one to obtain photographs of the attitudes of 

 the wings as seen from different points of view, but 

 it gives them an exaggerated appearance both as 

 regards the extent and the rapidity of the movement. 



To study an insect in free flight, a cardboard box 

 (Fig. 177) is placed in front of the object-glass, the 

 insect is confined by means of a pane of glass which 

 just touches the condensing lens. Being introduced 

 into this box, the insect immediately flies against the 



Fig. 178. — Fly crawling on a window-pane before taking to flight. 



glass, which previously should be placed at the focal 

 point of the object-glass. The insect's flight can be 

 w r atched, and at the desired moment the button can 

 be pressed which sets the film in motion. 



Fig. 178 was obtained in this way ; it represents a 

 fly crawling on the pane of glass and then taking 

 flight. The exposures were extremely short, as we 

 have previously mentioned, in order that the wings, 

 which moved very rapidly, might be well defined. 



With fenestrations 2 centimetres in breadth, the 

 actual exposure being 2 oV o °f a second, the photographs 

 were not distinct, at least not of the extremities of 



