LIVING TORPEDOS IN BERLIN. 493 



can be set at different positions in relation to each other. The two 

 wheels of each pair are electrically connected with each other ; the 

 three pairs which may be denoted by A, B, C are insulated from 

 each other by the axis. One wheel of each pair is constantly 

 immersed by its amalgamated rim in a mercury trough. The rim 

 of the other has eight copper and eight glass sectors of equal 

 length, and a copper spring presses on its circumference. 



One pair, A, is made to close and interrupt the primary circuit. 

 Another pair, B, is included in the secondary circuit, and it is 

 placed by the breadth of a half-sector in such a position in regard 

 to A, that its spring is against the glass when that of A comes to 

 the glass ; in this way the series of closing shocks alone is trans- 

 mitted. If, however, C is placed in regard to A by the breadth 

 of a half-sector, so that its spring rests upon glass when that of A 

 comes to the metal, then only the series of opening shocks is trans- 

 mitted. The same end may be attained in a simpler way, by using 

 only one of the pairs B or C in addition to A, and setting the 

 wheels first in one direction, and then in the other. 



In my experiments the machine was driven by a water-motor, the 

 axis of which was connected to the axis of the disjunctor by a pulley. 

 The change in direction of turning was accomplished by crossing 

 or not crossing the cord. The distance of the disjunctor from the 

 water-motor was so considerable, that the crossing of the cord 

 produced no perceptible difference in its tension. The number- of 

 shocks was 44 per second. 



The separation of the one series of shocks from the other is 

 indeed effected with the same degree of certainty only in so far as 

 the continuous contact of the spring in its passage can be relied 

 upon. This however seemed sufficient. For when opening shocks 

 were excluded, and by holding handles, I placed myself in the circuit 

 of the secondary coil and brought it to within one or two centimeters 

 of the primary, the sensation I experienced was quite uniform ; if, 

 however, the spring closing the primary circuit had jumped, each 

 opening would have been perceived by me as a violent shock. 



By these means I hoped to learn how the internal polarisation of 

 moist porous bodies and the negative polarisation of the electrical 

 organ, most nearly comparable with it, and perhaps also that of 

 muscles and nerves, depends upon the time occupied in equalisation, 

 when the amount of electricity is constant. The polarisation 

 switch was put into the secondary circuit, and the series of shocks 

 of 5" duration was led through the usual conducting vessels pro- 



