CHRONOPHOTOGRAPHY ON FIXED PLATES 59 



a superposition of images can be put to practical use. 

 Thus it gives greater intensity to those images which 

 represent the movements of least rapidity. One of 

 the very first applications of photography to the study 

 of movement was suggested by Messrs. Onimus and 

 Martin, in the year 1865. These investigators exposed 

 the heart of a living animal, and took a photograph of 

 it by leaving the lens permanently uncovered. The 

 photograph was found to have a double outline repre- 

 senting the two extreme positions of contraction and 



Fig. 4P.— A boxer represented in the two extreme portions of a movement. 



dilatation. At these two periods the heart remains 

 momentarily motionless, and its configuration is 

 imparted to the sensitized plate, whereas no clear 

 impression is left of it during the intermediate phases 

 of motion. 



Mr. Demeny had recourse to this method, which 

 had fallen into unwarranted oblivion, and with which 

 even he himself was previously unfamiliar. In study- 

 ing physical exercises, he took the photograph of a 

 man in the act of boxing in front of a dark screen. 



