484 OHM ON THE GALVANIC CIRCUIT. 



without committing any sensible error, be considered equal to 

 the limit value. 



A 

 Since the action of a coil of the circuit is -j-, while the ac- 



tion of the multipUer, in connexion with the same circuit, is 



A . 



— , it is evident that the two actions are in the same ratio to 



each other as the reduced length A and L ; if, therefore, we are 

 acquainted with the two actions, and with one of the two re- 

 duced lengths, the other may be found, and in the same manner 

 one of the two actions may be deduced from the other, and the 

 two reduced lengths. 



A 



Since the limit of the action of the multiplier is — , it in- 



A 



creases when X is invariable in the same proportion as the sum 

 of the tensions A in the circuit increases ; we may, therefore, by 

 comparing the extreme actions of the same multiplier in various 

 circuits, arrive at the determination of their relative tensions. 

 At the same time we perceive that the extreme action of the mul- 

 tiplier increases, when several simple circuits are formed into a 

 voltaic combination, and, indeed, in direct proportion to the 

 number of the elements. In this manner it is always in our 

 power, in cases where the multiplier in connexion with the 

 simple circuit produces a weakening effect, to cause it to in- 

 dicate any increase of force whatever. 



If we call the actual length of a coil of the multiplier I, its 



conductibility x, and its section w, then A = — , and conse- 

 quently the extreme action of the multiplier 



A 



whence it results that in the same circuit the extreme actions of 

 two multipliers of coils of equal diameter, are in the ratio to 

 each other of the products of their conductibility and their sec- 

 tion. These extreme actions are, therefore, in two multipliers, 

 which differ only in being formed of two distinct metals, in pro- 

 portion to the conductibility of these metals ; and when th"e 

 multipliers consist of similar convolutions, and of one metal, 

 their extreme actions are proportional to their sections. 



But all these determinations are based upon the supposition 

 that the action of a portion of the circuit on the magnetic 



