500 LIVING TOEPEDOS IN BERLIN. 



which I observed in a later series of experiments in using the 

 disjunctor arranged for opening shocks alone, described above in 

 4. But in any case, they would not explain the negative result 

 obtained here. 



I was unwilling to accept this rebuff, and determined to try 

 further the effect of a single opening shock of Ruhmkorff's induc- 

 torium at its full strength. The polarisation switch would not 

 answer this purpose, but a special switch had to be constructed, 

 which rendered it possible to open the secondary circuit (which 

 would otherwise have short-circuited the galvanometer) imme- 

 diately after the opening of the primary circuit and the passage of 

 the shock through the organ preparation, and then to close the 

 galvanometer circuit. If the ordinary arrangement had been 

 adopted, lateral discharges might have spread from the wedge-pads 

 placed on the preparation, over the conducting vessels and beyond, 

 and might possibly have left disturbing polarisations. On this 

 account, I did not venture to adopt the plan of closing the galvano- 

 meter circuit at two places situated between the conducting vessels 

 and the galvanometer, but I arranged that the clay points of 

 two non-polarisable conducting tubes connected with the galvano- 

 meter, should be so placed on the preparation, as to take up the 

 polarisation current by the same movement which opened first 

 the primary, and then the secondary current. 



Four corks are fixed upon a glass axis, which can be rotated 

 horizontally in wood bearings. Cork I carries a bent bar of 

 copper, which at the initial position of the switch, by dipping into 

 two mercury cups, closes the primary circuit of the inductorium, in 

 which three large Bunsen cells are included. Each of the corks 

 II and III carries a non-polarisable conducting tube, the clay 

 point of which in the first instance is suspended above the organ 

 preparation. Cork IV carries a copper hook, one end of which is 

 the terminal of the secondary coil and dips into a mercury cup. Its 

 other end is connected with the other terminal of the coil perma- 

 nently, but is movable. When the glass axis is turned from its 

 initial position, the primary circuit opens, whilst the secondary is 

 still closed. The shock passes through the preparation, to which 

 it is led by amalgamated zinc plates in solution of zinc sulphate, 

 and by zinc pads protected by clay shields. Immediately after, 

 the secondary circuit opens, and thereupon the clay points touch 

 the preparation. Two marks are made on the milled edge of the 

 wood disk which serves to turn the axis, of which one shows the 



