204 



Mr. G-. J. Burch. On the Interpretation of [Feb. 11, 



intensity, neutralises it and produces zero P.D. for a period equal to 



b— a 



v 



Since the value of (b - a)/v can be varied by shifting the leads 

 A and B, it follows that 6 can be determined by ascertaining at what 

 distance between the leads the two phases of the P.D. follow one 

 another without a zero interval between, for the sequence of potential 

 differences will be 



(1) With A and B close together, 



0, +, 0, 0. 



(2) With A and B at one particular distance, 



0, + , 0. 



(3) With A and B far apart, 



0, + , 0,-, 0. 



The case of leads on either side of P is similar, the phases of the 

 resulting P.D. varying according to the relation 



(k-l)[v> 0; 0, ±, 0, + , 0. 

 (k-l)/v - 0; 0, ±, + , 0. 



(k-i)/v<e ; o, ±, o, +, o. 



II. Variations of P.D. between Tim Points of a Bundle of Lineojr 

 Conductors traversed by a Source of Electromotive Force. 



Hitherto it has been assumed that the rise of P.D. at the wave- 

 front of electrical activity is sudden, and its fall equally sudden at the 

 end of the wave, and also that the electrical change is not complicated 

 by the structure of the linear conductor in which it occurs. 



It is necessary to investigate farther the modifications which may 

 result when a number of such linear conductors act together. 



In my paper on the " Time Relations of the Capillary Electro- 

 meter,"* I pointed out that in the case of muscle the rise of 

 potential difference at the wave-front is not sudden, and the same is 

 shown with respect to nerve in the analyses published by Professor 

 Gotch and myself. Moreover, in the discharge of the electrical organ 

 of Malapterurus, the E.M.F. is gradually developed, although in this 

 •case the phenomenon cannot be accounted for by propagation. There 

 is sufficient evidence to warrant the introduction into the formula of a 

 term expressing gradual development of E.M.F. 



In dealing with the phenomena of a bundle of linear conductors, 

 -three things have therefore to be taken into account, viz. : — 



* ' Phil. Trans.,' A, vol. 183, pp. 100, 104. 



