274 



M. Wartmann's First Memoir 



at a length of additional wire, such that the lengthened circuit 

 is an infinitely worse conductor than the invariable circuit (X). 

 b. The value of the ratio of the arithmetical progression 

 varies with the nature and the dimensions of the additional 

 wire employed {fi). 



26. Fourth case. — This was studied like the second, with 

 the apparatus mentioned (23.). The laws which govern it 

 are — 



a. For the additional lengths of the inductor wire, increa- 

 sing in geometrical progression, the deviations of the rheo- 

 meter, which measure the difference of intensity of the two 

 currents simultaneously induced, increase according to an 

 arithmetical progression, the first term of which is zei'o, and 

 the last term of which is equivalent to the action of the con- 

 stant inducing wire, taken by itself, even at an infinite additional 

 length (v). 



b. From whence it results, that for additional lengths, which 

 increase in geometrical progression, the differences between 

 the effects ofinduction, produced by the two wires simultane- 

 ously, and those which the variable wire produces by itself, 

 diminish according to an arithmetical progression (^). 



c. The value of the ratio of these arithmetical progressions 

 varies with the nature and the dimensions of the additional 

 wire employed (o). 



d. The presence or the absence of bars of soft iron in the 

 helixes only modifies the intensity of the induction (tt). 



27. The subjoined Tables are intended to prove the enun- 

 ciations (v) and (o). 



