384 Dr. E. Goldstein on the Electric 



column; but it appeal's that the position and properties of each 

 separate layer depend mainly or entirely upon the position 

 and properties of the layer preceding it on the side of the 

 kathode. The influence of the kathode on all the members of 

 a stratified column, \shich appears so markedly in the experi- 

 ments just described, would then be only an indirect one, inas- 

 much as the properties of the kathode determine the proper- 

 ties of the kathode-light ; this determines the position and 

 properties of the first positive layer, this the position and 

 properties of the second layer, and so on. This conclusion is 

 drawn from experiments on the secondary negative light. 



We saw that in a cylinder where the kathode is moved, all 

 the layers move in the same direction as the kathode and 

 through an equal distance. If now we introduce into the 

 cylindrical tube C (fig. 4), with movable kathode K, a por- 



tion of tube R fitting C closely and also movable in it, having 

 a narrow opening at x, then, as already explained, x acts as a 

 secondary negative pole for the portions of the whole discharge 

 between x and the anode A*. 



If now, whilst II retains the same position in any portion 

 of the discharge-cylinder, the kathode K is moved, all the 

 layers between K and x move as in the previous experiments ; 

 but the layers between x and A remain immovable, in spite of 

 the displacement of the kathode. 



If, on the other hand, K be fixed and II be displaced, so that 

 the secondary negative pole x moves with the secondary nega- 

 tive light radiating from it, then all the layers between x and 

 A are displaced exactly like the stratifications of a simple 

 cylinder having a metallic kathode at x. 



If the separate layers of the discharge show different colours, 

 then we observe further that, when K moves, the colours of 

 all the layers between K and x behave as previously described 



* A may with advantage be made short, and placed somewhat excen- 

 trically but parallel to the axis of the tube, so that it may not be struck 

 by the movable piece R. 



