104 DOVE ON THE ELECTRICITY OF INDUCTION. 



cannot be determined to be equal when they cause the needle 

 of the same galvanometer to deviate in the same degree^ for 

 according to Ohm's theory, the intensity of a current is equal 

 to the electromotive force which produces it, divided by the re- 

 sistance to conduction of all the parts through which the cur- 

 rent passes ; therefore, in the case where the resistance to con- 

 duction, a part of which only is due to the wire of the gal- 

 vanometer, is unequal, a like amount of deviation in the needle 

 of the galvanometer must prove an inequality to exist in the 

 electromotive force. This inequality must become apparent 

 if the resistance of both cuiTcnts is increased or diminished in 

 the same ratio. In this manner it is explained, for instance, 

 why a thermo-circuit and a galvanic circuit, both equally affect- 

 ing a galvanometer, have a very different effect when a fluid is 

 interposed in the connecting circuit. The same reason explains 

 why a voltaic pile and a galvanic battery, which have a like 

 action upon the galvanometer, produce very different effects upon 

 the human body or in a decomposing cell. But if the resistance 

 to conduction is the same for both currents, if, for example, 

 they both pass through the same conductor, and produce the 

 same deviation in the galvanometer, then an equal amount of 

 electromotive force must be ascribed to both. If these currents 

 produce different effects in cases where the resistance to con- 

 duction, on being changed in an equal degree in both, still re- 

 mains the same, this difference can no longer be attributed to a 

 difference in the electromotive force, but some other cause must 

 be sought to explain it. 



If an electric current is understood to be the equalization of 

 an electric antagonism, however this may have been caused, then 

 there are two things to be considered, — the original yb?re of this 

 antagonism, and the time which is required completely to equal- 

 ize it. Differences in the action of two currents, which have been 

 produced by the equalization of an equal amount of electric 

 antagonism, must therefore be ascribed to the difference of time 

 in which this equalization is effected. 



If the magnetic, chemical, physiological and calorific effects of 

 an electric current depended equally upon its povjer and dura- 

 tion, then two currents, known to be equal in one of those re- 

 spects, should likewise be equal in the other three. This however 

 is not the case. 



With regard to the relation between the galvanometric effect 



