DESCRIPTION OF THE APPARATUS ll 



or in a place illuminate 1 by red light, provided that 

 the object to be photographed is itself a luminous 

 body, such, for instance, as an incandescent lamp ; the 

 latter gives excellent results. 



L. Soret was the first to make use of this arrange- 

 ment. At night, on the stage of a theatre, lighted 

 only by a few red lanterns, he studied the movements 

 of dancers, by fastening little incandescent lamps to 

 their heads and feet. In this way Soret obtained some 



Fk;. 52.— Arrangement employed by Messrs. Demeny and Quenu for studying (by 

 means of chronophutograpny) aunorma.ities iu walking. 



very curious trajectories, in which the curves obtained 

 showed a beautiful and regular interlacement. 



Messrs. Demeny and Quenu similarly made use of 

 incandescent lamps in analyzing, by means of chrono- 

 photography, the characteristic gaits of patients 

 afflicted with various kinds of lameness. 



A room in a hospital was provided with red windows 



(Fig. 52), a track was marked out on the floor for the 



patient to walk on, and the apparatus was placed at 



a suitable distance. Incandescent lamps were fixe 1 



7 



