OHM ON THE GALVANIC CIRCUIT. 479 



change places with each other ; because, according to the 

 laws of tension obsei-ved with respect to metals, this trans- 

 position would, it is true, alter the individual tensions, but 

 not their sum. 



2. The intensity of a galvanic current continues the same, al- 

 though a part of the cii'cuit be removed, and another pris- 

 matic conductor be substituted in its place, only both must 

 have the same reduced length, and the sum of the tensions 

 in both cases remain the same ; and vice versa, when the 

 current of a circuit is not altered by the substitution of one 

 of its parts for a foreign prismatic conductor, and we can 

 be convinced that the sum of the tensions has remained the 

 same, then the reduced lengths of the two exchanged con- 

 ductors are equal. 



3. If we imagine a galvanic circuit always constructed of a 

 like number of parts, of the same substance, and arranged 

 in the same order, in order that the individual tensions may 

 be regarded as unchangeable, the cui'rent of this circuit in- 

 creases, the length of its parts remaining unaltered, in the 

 same proportion in which the sections of all its parts in- 

 crease in a similar manner, and the sections remaining un- 

 altered, in the same propoi'tion in which the length of all 

 its parts uniformly decrease. When the reduced length of 

 a part of the circuit far exceeds that of the other parts, the 

 magnitude of the cuirent will principally depend on the 

 dimensions of this part ; and the law here enounced will 

 assume a much more simple form, if, in the comparison, 

 attention be solely directed to this one part. 



The conclusion arrived at in II. 2. presents a convenient 

 means for the determination of the conductibility of various 

 bodies. If, for instance, we imagine two prismatic bodies, 

 whose lengths are I and I', their sections respectively w and w', 

 and whose powers of conduction are x and x', and both bodies 

 possess the property of not altering the current of a galvanic 

 circuit when they alternatively form a portion of it, and both 

 leave the individual tensions of the circuit unchanged, then 



I _ J<_ 



X W K uJ 



consequently 



, / /' 

 X : x' = - : -, ; 



