Dr. "\V. H. Eccles on Coherers. 



883 



indicated in fig. 8 by curves I., III., separated by the case II. 

 In class I. the curve has two vertical tangents ; the condition 



Electromotive-Force 



for this is p >8r. If when the coherer is in use the values 

 of e and c pass those corresponding to the lower bend of the 

 curve, the original values of c and e can only be regained by- 

 interrupting the current by external agency : the coherer is 

 not "self-decohering." In class III. p Q <Sr : there is no 

 vertical tangent, and the coherer is self-restoring. In 

 case II. p — 8r. All these cases can be realized, with 

 patience. 



To return to the problem of the small fluctuations of the 

 current from its equilibrium value when the arbitrary small 

 variation (Spi) is imposed on the system by the arrival of a 

 train of oscillations at the time t = 0. Equations (1') and (2) 

 become 



1 rf&i +(r + ft)fc l »-« l «p 1 . . . . (4) 



dt 



d&t>i 

 dt 



-f nSpi= —2(n — rn) — 8c 



Here 



n kp ac{ 2 +m, 



(5) 

 (6; 



and p lt ci are corresponding equilibrium values of p and c. 

 Equations (4) and (5) give 



L^ + (L»+r+ ft )^+{«(r+p l )-2(n-»)h}V l =0, 



which can bo written in the form 



[D'+aD + ftlSpissO. 



0) 



(8) 



