44 Prof. PoggendorfF 07J the intensity of current of the 



thick multiplier wire ; and then, when to this a wire of Ger- 

 man silver, about 50 feet in length and of the same thickness, 

 the resistance of which is nearly equal to that of a 50-feet long 

 copper wire of the same thickness, was added. To render the 

 galvanometer suited for the measurement of forces of some in- 

 tensity, a similarly directed position was given to its needles. 



In three experiments made at different times, the intensity 



of the current corresponding to the smaller resistance, which 



may be expressed for each by 100, sunk, by the insertion of 



the greater resistance, in the following proportion: 



Copper-circuit. Iron-circuit. 



100 : 17-G 100 : 12'3 



100 : 19-6 100 : 14-4 



100 : 17-2 100 : 13-6 



The greater weakening current of the iron circuit is here so 

 evidently expressed, that no doubt can remain as to its real- 

 ity, especially if we consider that it is the intensity of the cur- 

 rent of this circuit which, as the greater, in both cases, and 

 especially in the smaller resistance, has been estimated too low 

 more than that of the copper circuit. It may, therefore, be 

 regarded as good as proved by these measurements, although 

 they are but approximations, that the ascendency of the in- 

 tensity of the current of the iron-circuit is founded on the 

 smallness of its resistance of transition. 



In the just- mentioned measurements, the current of the 

 iron circuit was more weakened than that of the copper cir- 

 cuit by the interposition of the 50-feet long German silver 

 wire. It remained, nevertheless, always considerably stronger 

 than the latter, as will be evident from the following compa- 

 rison of the intensities of the current of both circuits: 



Iron : Copper Iron : Copper 



with smaller resistance. with greater resistance. 



267 : 100 187 : 100 



237 : 100 175 : 100 



225 : 100 178 : 100 



But it is evident that we can, by continued increase of the 

 inserted resistance, — presupposing naturally that it be both as 

 to size, immersion, and distance of the plates, equal for both 

 circuits, — at last arrive so far as to make the current of the 

 iron circuit not only as weak, but even weaker than that of the 

 copper circuit. 



The author has attempted to test the theory even on this 

 interesting point, but he did not succeed, with the means at 

 his disposal, with equal and indeed with the stated size of the 

 plates, even in attaining an equality between the intensity 

 of current of both circuits. The currents, it is true, can be 



