110 MOVEMENT 



to Paris, in August of 1881, he brought us several 

 prints of pigeons photographed in - 5 l part of a second. 

 Each of these photographs represented a number of 

 flying pigeons in different positions, one with its 

 wings raised, another with them in front, and another 

 with them depressed. These positions appeared to us 

 to coincide almost exactly with those which we had 

 predicted from studying the mechanism of flight by 

 the graphic method.* 



But beyond the fact that these photographs were 

 not sufficiently clear, they failed in that which gave so 

 much interest to those of the horse in motion, namely, 

 the arrangement in a series which showed the successive 

 attitudes and positions. This is because it is impos- 

 sible to apply, in the case of a bird in free flight, the 

 method which succeeded so well in the case of a horse, 

 and which depended on the animal itself opening a 

 series of photographic shutters. 



We determined to invent an apparatus based on the 

 same principles as that of M. Janssen, but capable of 

 giving a series of photographs at very short intervals 

 of time, — ^2 °f a second instead of the 70 seconds which 

 separated the photographs of the astronomical revolver 

 — so as to procure the successive phases of the move- 

 ments of the wings. This instrument, gun-like in form 

 (Fig. 74), made it possible to follow the flight of a bird 

 by aiming at the object in the ordinary manner. The 

 moment the trigger was pulled the sensitized plate 

 received an impression, then moved on only to receive 

 another, and so on, but always stopping each time that 

 the opening of the shutter allowed the light to fall on 

 the plate.f 



* "The Graphic Method." p. 211. 



t The following are the details of the construction. The barrel of 

 the gun is a large blackened tube (Fig. 75), which contains an 

 ordinary photographic lens. At the hindermost part, mounted firmly 



