OHM ON THE GALVANIC CIRCUIT. 415 



the kind hitherto mentioned, the quantity of electricity passing 

 through a section of it in a given time is everywhere the same, 

 because at all places and in each moment the same quantity in 

 the section leaves it on the one side as enters it from the other, 

 but in different circuits this quantity may be very different : 

 therefore, in order to compare the actions of several galvanic 

 circuits inter se, it is requisite to have an accui-ate determination 

 of this quantity, by which the magnitude of the current in the 

 circuit is measured. This determination may be deduced from 

 figure 3 in the following manner. It has already been shown 

 that the force of the electric transition in each instant from 

 one element to the adjacent one is given by the electric differ- 

 ence between the two existing at that time, and by a magnitude 

 dependent upon the kind and form of the particles of the body, 

 viz. the conductibility of the body. But the electrical difference 

 of the elements in the part B C, for instance, reduced to a con- 

 stant unit of distance, Avill be expressed by the dip of the line H I 



I H' . . 



or by the quotient „ ; if, therefore, we now indicate by x 



the magnitude of the conductibility of the part B C, 

 X . IH' 

 BC 

 will express the force of the transition from element to element, 

 or the intensity of the current in the part B C ; consequently if 

 to represent the magnitude of the section in the part B C, the 

 quantity of electricity passing in each instant from one section 

 to the adjacent one, or the magnitude of the current, will be ex- 

 pressed by 



X . M ■ I H' 

 BC ' 

 or if S represent this magnitude of the current, we have 



^ K.m.lW 



k5 = 



BC ' 

 A 



and if we substitute for I H' its value 



A X . CO 



S = 



L • BC • 



Hitherto the letters A, X', A" have represented lines which are 

 proportional to the quotients formed of the lengths of the parts 

 A B, B C, CD, and the products of their conductibilities and 

 their sections. If we restrict for the present this determination, 



