HISTORY OF CHRONOPHOTOORAi'HY. 



325 



clockwork R, which led a long paper ribbon over rollers. The rota- 

 tion of the disk made an electric contact at each passage of a slit, in 

 consequence of which an electro-magnet squeezed the hand and stopped 

 it long enough for the exposure. 



Type b: It was necessary to avoid the extreme inconvenience of 

 only being able to photograph within the dark room. A small porta- 

 ble box, B, was therefore made for the fillet, which, having been tilled 

 in the dark room, could he* carried out 

 with the rest of the chronophotographic 

 apparatus, as shown in tig. 13. The 

 results were more satisfactory. 



Type c: Ultimately the application of 

 electricity was given up, and the motion 

 and stoppages of the film, instead of be- 

 ing governed by an independent clock- 

 work, were connected with the move- 

 ments of the disk. 



No. 9. Double- action chronophoto- 

 qraphy. — AVith a view of obtaining; an 

 apparatus which should, at pleasure, 



either work upon a fixed plate or upon a moving film, an instrument 

 was constructed represented by No. 9 in the glass case. This apparatus 

 (tig. 14) is composed of a fore part, which slides in grooves. This fore 

 part carries the objective and is cut so as to allow the shutter-disk to 

 pass. The movement of the latter is governed by a rod of variable 



Fig. 14. 



length (so as to permit focusing) connecting with clockwork within the 

 after part of the apparatus. In this after part can be placed an 

 ordinary plate holder for chronophotography on a fixed plate; or, if 

 desired, the plate holder being removed, movable films may be intro- 

 duced. These go into a back chamber, the open lid of which is shown 

 in the figure. The film ribbons could be inserted in daylight in con- 

 sequence of their being prolonged at both ends by ribbons of opaque 



