502 LIVING TORPEDOS IN BERLIN. 



to the heterodromous induction currents. For instance, I obtained 

 with 5000 turns at a distance of 20 mm. 



4 - 85 t + 360 I - 57 t + 135- 



But the heterodromous shocks never produced relatively positive 

 polarisation. 



There was still the possibility that the latter although present, 

 might be masked by relatively negative polarisation. Although 

 the opening shocks of the inductorium, by using the condensator are 

 only of very short duration, I wished also to employ Leyden jar 

 discharges, so that I should have left nothing untried. The same 

 switch served for this as for the Ruhmkorff's opening shocks. In 

 the first series of experiments on the same seventh Torpedo, Prof. 

 Christiani discharged the jar, charged by Holtz' machine, through 

 the preparation, and I put the clay shields in contact with it as 

 soon as I had heard the sparks. The preparations were perhaps 

 accidentally better than those which had been exposed to the 

 induction shocks ; for instance, we obtained 



1-448 t + 55 |- ii t + 48- 



It was however clear, that the experiments must be repeated with 

 a fish with greater functional activity. 



These latter and also the renewed experiments with the induc- 

 torium were performed on the eighth torpedo, which had just been 

 killed. The following contrivance was now adopted. A fifth cork 

 at the free end of the glass axis of the switch, carried a strong brass 

 wire bent at right angles, one leg of which formed a prolongation 

 of the axis, and was connected with an amalgamated zinc plate 

 which was to conduct the shock to the organ preparation. The 

 other leg, perpendicular to the axis, terminated in a closed ring. 

 The charged jar was disposed so that its outer coating was con- 

 nected with the other zinc plate. On turning the axis between 

 the marks on the middle edge of the disk, the ring came so near 

 the knob of the inner coating, that the spark sprang over and led 

 the shock to the preparation a short time before the clay points 

 reached it. In this series of experiments, the Leyden jar (with 

 a coating of 565 square centimeters) was charged at the conductor 

 of an ordinary electrical machine, for by regulating the number of 

 revolutions of the disk, a greater uniformity and a more certain 

 gradation of charge was ensured than in charging with the influ- 

 ence machine. 

 % The experiments succeeded extremely well, without however 



