produced by various kinds of electric discharge 425 



In the ordinary mode of taking shocks by passing them through the body 

 from one hand to the other, the sensations arise from disturbances in different 

 nerves, and these being affected in a different ratio by discharges of different 

 kinds, it becomes difficult to determine whether, on the whole, the sensation 

 of one discharge or the other is the more intense. 



I find that when the hands are immersed in salt water the quality of the 

 sensation depends on the value of T. 



When T is very small, say o-ooooi second, and C is large enough to produce 

 a shock of easily remembered intensity in the wrists and elbows, there is very 

 little skin sensation, whereas when T is comparatively large, say o-oi second, but 

 still far too small for the duration of discharge to be directly perceived, the 

 skin sensation becomes much more intense, especially in one place where the 

 skin may have been scratched, so that it becomes almost impossible so to con- 

 centrate attention on the sensation of the internal nerves as to determine 

 whether this part of the sensation is more or less intense than in the discharge 

 in which T is small. 



There are two convenient methods of producing discharges of this type. 



(i) If a condenser of capacity K is charged to the potential V, and dis- 

 charged through a circuit of total resistance R (including the body of the 

 victim), F 



C-~, r=KK. 



K 



The whole quantity discharged is Q = CT = VK, and if r is the resistance 

 of the body of the victim, the work done by the discharge in the body is 



(2) If the current through the primary circuit of an induction coil is y, 

 the coefficient of mutual induction of the primary and secondary coils M, that 

 of the secondary circuit on itself L, and the resistance of the secondary circuit R, 

 then for the discharge through the secondary circuit when the primary circuit 

 is broken, 



- 

 * ~ R ' 2 L R- 



I first tried the comparison of shocks by means of an induction coil, in which 

 M was about 0-78 and L about 52 earth quadrants, and in which the resistance 

 of the secondary coil was 2710 Ohms. By adding some German silver wire to 

 the primary coil, its resistance was made up to nearly I Ohm, and the primary 

 thus lengthened, another wire of the same resistance, and a variable resistance Q, 

 were made into a circuit. One electrode of the battery was connected to the 

 junction of the two equal resistances, and the other was connected alternately 

 to the two ends of the resistance Q, so that the current through the primary 

 was varied in the ratio of the primary P to P + Q, while the resistance of the 

 battery-circpit remained always the same. When the smaller primary current, 



