196 



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



A source of electromotive force is developed at a given point in a 

 bundle of linear conductors imperfectly insulated from each 

 other, is propagated* in both directions along the bundle, and 

 finally subsides. It is required to investigate the variations of 

 potential difference between any pair of points on the con- 

 ductors. 



Obviously the conditions are extremely complex, and a complete 

 solution is impracticable because, from the nature of the case, it is 

 impossible to determine the amount of the leakage from each con- 

 ductor into the bundle. It is possible, however, to separate from the 

 results those which depend upon purely physical conditions, and thus 

 to clear the ground for the discussion of the truly physiological 

 phenomena. In analysing photographs taken in this laboratory I 

 have met with illustrations of all the points brought forward in this 

 paper. 



In thus dealing with the problem, it is necessary to take the follow- 

 ing considerations into account : — 



(1.) That the linear conductors (or briefly the conductors) consti- 

 tuting the bundle are not necessarily all of the same length. 



(2.) That the electrical change originates in each conductor at a 

 certain point of its length, from which it is propagated simul- 

 taneously in both directions. 



(3.) That the points at which the electrical change originates in the 

 different conductors may be all situated in the same cross-sec- 

 tion of the bundle, or may be distributed along a certain portion 

 or portions of its length. 



(4.) That the development, as also the subsidence, of the E.M.F. at 

 any given point of a conductor may conceivably be gradual or 

 sudden, i.e., the change from zero to maximum, or vice versa, 

 may be instantaneous, but is not necessarily so. 



(5.) That the time relations and intensity of the electrical change 

 may be temporarily or permanently modified at a given point 

 in any or all the conductors of the bundle. 



In stating the problem it is necessary to put it into such a form as 

 will represent these conditions. 



The simplest way of doing so is to deal first with the case of the 

 single linear conductor, and to express the electrical changes in it as 



* [ Note, added April 10, 1902. — I can find no exact physical analogue to this 

 phenomenon, and no other single word to express it than this physiological term. 



It has been, I believe, compared to the lighting of a train of gunpowder in the 

 middle. The flame spreads outwards in both directions, but dying out first in the 

 middle, separates into two tracts of flame of practically constant length, travelling 

 away from each other.] 



