68 



MOVEMENT 



certain movements which cannot be chronophoto- 

 graphed on a fixed plate, and which must be repre- 

 sented as a series on a long photographic film, which 

 can be unrolled at the back of the camera. 



The chronophotographic camera, as shown in Fig. 

 45, meets all the above requirements ; but, for the 

 present, we must be content to describe only those 

 parts which are necessary for taking photographs on 

 fixed plates. The apparatus consists of two halves 

 united by bellows. The hinder part slides on a rail 



Fig. 45.— Arrangement of an apparatus adapted for all the purposes of chrono- 

 photograpby (scale -j^). 



by means of a screw-rack for convenience in focussing, 

 and into this part the dark slides are introduced. 

 The objective is contained in a box (Fig. 46) which 

 is cleft beneath, and accurately fitted so as to slide 

 into the front part of the apparatus. The cleft under 

 the box is continued into the mounting of the objec- 

 tive, and thus divides the object-glass perpendicularly 

 to its principal optical axis, and allows room for the 

 fenestrated diaphragms. The latter by their revolu- 

 tions regulate the intermittent exposures. One end of 

 the bellows fits into the box containing the objective, 

 while the other, attached to the hinder part, com- 



