OHM ON THE GALVANIC CIRCUIT. 459 



from one extremity to the other, to the extent of an entire 

 tension. 

 b. When any place of the circuit is disposed by any circum- 

 stance to change its electric state, all the other places of 

 the circuit change theirs at the same time, and to the same 

 amount. 

 16. We will now imagine a galvanic circuit, composed of two 

 parts, P and P', at whose two points of contact a different elec- 

 tric tension occurs, which case comprises in it the thermal cir- 

 cuit. If we call u the electroscopic force of the part P, and zt' 

 that of the part P', then, according to the preceding paragraph, 

 as here, the case there noticed is repeated twice, in consequence 

 of the equation (c), 



u =fx + c 

 for the part P, and 



v! —f'x + c' 



for the part P', where/, c,f', d are any constant magnitudes to 

 be deduced from the peculiar circumstances of our problem, 

 and each equation is only valid so long as the abscissae refer to 

 that part to which the equations belong. If we now place the 

 origin of the abscisste at one of the places of contact of the 

 part P, and suppose the direction of the abscissae in this part 

 to proceed inwards^ moreover, designate by I the length of the 

 part P, and by I' that of P' ; and, lastly, represent by u'^ and u^ 

 the values of u and «' at the place of contact where x-=o, and 

 by Mg and m'j the values of u and vJ at the place of contact where 

 j:" = /, we then obtain 



'h- 



=/' {l + l') +C n,=c 



If we now designate by a the tension which occurs at the place 

 of contact where x = o, and by a' that which occurs at the place 

 of contact where x = I; and if we once for all assume, for the 

 sake of uniformity, that the tension at each individual place of 

 contact always expresses the value which is obtained when we 

 deduct the electroscopic force of one extremity from the elec- 

 troscopic force of that extremity belonging to the place in ques- 

 tion, upon which the abscissa falls before the abrupt change takes 

 place — (it is not difficult to perceive that this general rule con- 

 tains that advanced in the preceding paragraph, and which, in 

 fact, expresses nothing more than that the tensions of such 



