234 



MOVEMENT 



Photographs of Birds taken from Different Aspects. — 

 If one is dealing with a movement which is quite 

 invisible to the unaided eye, a single series of photo- 

 graphs taken only from one point of view is usually 

 quite insufficient ; it does not give an accurate idea of 

 the movement at any particular moment. Therefore, 

 it is desirable to take photographs from one or two 

 different angles. For instance, one photograph should 

 be taken as the bird is flying towards the camera ; 

 another as it flies across it ; and a third should be 

 taken from above, with the camera looking down- 



Fig. 164.— Flight of a pigeon. The photograph is taken from above (cbronophoto- 

 graph on a fixed plate, 25 images to the second). 



wards. Fig. 164 shows a photograph of a pigeon 

 taken from above. The camera was directed vertically 

 downwards at a distance of 12 metres from the bird. 

 In spite of the confusion resulting from so many 

 images (25 to the second), the curious positions of the 

 wings at different moments are clearly shown. The 

 various positions can easily be distinguished after a 

 little practice in interpreting the meaning of this kind 

 of photography. 



Chronophotography on Moving Films. — To take a 

 large number of images per second without confusion, 



