LECT. XII. XII. MASSON'S APPARATUS. 



249 



sisted of a metallic wheel, R, supported on a metallic axis, 

 and turned, by means of a handle, upon two amalgamated 

 cushions. One of these was in communication with one of 

 the poles of a pile, P, whilst the second pole was in contact with 

 a wire, which, after being wound spirally around a cylinder 

 of soft iron, M, terminated in a fixed metallic plate applied 

 to the teeth of the wheel. 



When we revolve the wheel, the circuit closes every 

 time the plate touches one of the teeth, and the circuit is 



Fig. 19. 



Masson's Apparatus. 



interrupted when one of the non-metallic spaces comes in 

 contact with it. By applying the moistened hands to the 

 two extremities, A and B, of the conductor when the wheel 

 revolves, a series of violent shocks is obtained. If the 

 movements of the wheel be sufficiently rapid, these succes- 

 sive passages produce a very painful tension in the arms ; 

 the experimenter cannot let go the conductors, but invo- 

 luntarily grasps them with great force. 



Masson, by means of this apparatus, and a pile, formed 

 of a small number of elements, succeeded in killing a cat 

 in five or six minutes. 



He found that these shocks, and this spasmodic tension, 

 disappeared by communicating a great rapidity of the wheel. 

 Pouillet proved, that when the duration of the interval be- 



