Transmission of Electric Disturbances, 133 



that the atoms recombine simultaneously after a time T. 

 Then, when the atoms have recombined as far as possible, 

 since there are a certain number, say N, of positively electrified 

 atoms sticking to the negative electrode, there must be N 

 negative atoms left free : in order that the discharge should 

 travel with the velocity Y, these N negative atoms must be 

 situated along the line of discharge at a distance VT from the 

 negative electrode. Hence if we suppose that the molecules 

 along a length YT of the Grotthus chain were split up before 

 discharge commenced, the free negative atoms would appear 

 at the end of this chain, and the discharge would travel with 

 the velocity Y; and thus, by properly choosing the length of 

 the chain, we can make the velocity what we please. 



The N free atoms at the end of the chain would act as a 

 new negative electrode, and other Grotthus chains of length 

 YT would decompose at the end of this, and so on. The dis- 

 charge would thus be broken up into a series of separate 

 currents, each of length YT ; and in this way the discharge 

 through each element would be able to satisfy the condition 

 imposed on it by the surrounding dielectric and travel with 

 the velocity of light. 



According to our view, this breaking-up of the current into 

 a series of separate pieces shows itself in the stratifications 

 observed when the discharge passes through a gas at low pres- 

 sure. The behaviour of a striated discharge in a magnetic 

 ■field seems almost to prove that it is made up of a series of 

 separate discharges. For " if a magnet be applied to a striated 

 column, it will be found that the column is not simply thrown 

 up or down as a whole, as would be the case if the discharge 

 passed in direct lines from terminal to terminal, threading the 

 striae in its passage. On the contrary, each stria is subjected 

 to a rotation or deformation of exactly the same character as 

 would be caused if the stria marked the termination of flexible 

 currents radiating from the bright head of the stria behind it, 

 and terminating in the hazy inner surface of the stria in ques- 

 tion. An examination of several cases has led the authors of 

 this paper to conclude that the currents do thus radiate from 

 the bright head of a stria to the inner surface of the next, and 

 that there is no direct passage from one terminal of the tube 

 to the other." (Spottiswoode and Moulton, Phil. Trans. 1879, 

 parti. p. 205.) 



Goldstein, and Spottiswoode and Moulton, from the study of 

 the behaviour of the striated discharge, have independently 

 arrived at the conclusion that each stria represents a separate 

 discharge. Thus Goldstein (Phil. Mag. [5] x.p.183) says : — 

 " By numerous comparisons, and taking account of all appa- 



