134 Prof. J. J. Thomson on the Velocity of 



rently essential phenomena, I have been led to the following 

 view : — 



" The kathode-light, each bundle of secondary negative light, 

 as well as each layer of positive light, represent each a sepa- 

 rate current by itself, which begins at the part of each structure 

 turned towards the kathode, and ends at the end of the nega- 

 tive rays or of the stratified structure, without the current 

 flowing in one structure propagating itself into the next, 

 without the electricity which flows through one also traversing 

 the rest in order. 



" I suspect, then, that as many new points of departure of 

 the discharge are present in a length of gas between two elec- 

 trodes as this shows of secondary negative bundles or layers — 

 that as, according to experiments repeatedly mentioned, all 

 the properties and actions of the discharge at the kathode are 

 found again at the secondary negative light and with each 

 layer of positive light, the intimate action is the same with 

 these as it is with those." 



Spottiswoode and Moulton (Phil. Trans, parti. 1879, p. 201) 

 express much the same opinion : — " If, then, we are right in 

 supposing that the series of artificially produced hollow shells 

 are analogous in their structures to striae, it is not difficult to 

 deduce from the explanation above given the modus operandi 

 of an ordinary striated discharge. The passage of each of the 

 intermittent pulses from the bright surface of a stria towards 

 the hollow surface of the next may well be supposed, from its 

 inductive action, to drive from the next stria a similar pulse, 

 which in its turn drives one from the next stria, and so on. 

 Thus the procession in the naturally and artificially striated 

 columns are precisely similar ; save that in the case of the 

 latter the pulses from the several striae are excited by induc- 

 tion from without the tube, while in the case of the former 

 the induction is that of the discharge itself in its passage from 

 stria to stria. The passage of the discharge is due in both 

 cases to an action consisting of an independent discharge 

 from one stria to the next ; and the idea of this action can 

 perhaps be best illustrated by that of a line of boys crossing a 

 brook on stepping stones, each boy stepping on the stone 

 which the boy in front of him has left." 



The laws governing striation seem to be in accordance with 

 those wdiich follow from the view expressed above, that the 

 distance between two striae is the distance passed over by light 

 during the time taken by the atoms split up in the chain to 

 recombine. 



Thus the distances between consecutive striae increase when 

 the pressure of the gas diminishes ; but when the pressure 



