54 Dr. A. Stoletow on the Magnetizing -Function of 



Consequently 0=108-23 sc; A = 243'46 sc. 

 Hence we obtain 



f =8-3700. 10*, ;= 4 -2656^^, 



and; lastly, 



£ = 136-22, B = 71-830 mg ^ . 



mm, 3 sec. 



With feebler currents this method required a modification, as 

 the measurement of such currents by removing the roll would 

 be too inexact. This could be remedied by inserting a bridge 

 before the wire P, so that only the current in P would be weak- 

 ened. Mostly, however, for such cases the arrangement was 

 adopted which Kirchhoff employed in his measurement of the 

 induction-constant. The series K (PI. III. fig. 4), the primary 

 wire P of the ring, the secondary wire S, and the multiplier M 

 of the magnetometer formed a circuit, which was divided into 

 two branches by means of a bridge B of small resistance. By 

 the commutator C Y the current in P was reversed, and by the 

 commutator C 2 the disposition of the wire of the multiplier was 

 changed. 



The currents induced in S when C 1 is shifted pass almost ex- 

 clusively in the circuit SBM ; while the current from the gal- 

 vanic apparatus passes for the most part in K B P, only a small 

 portion of it going through M and being used for the measure- 

 ment. As the reduction-constant of the multiplier, which serves 

 for the determination of absolute current-intensities from ob- 

 served readings, had been previously ascertained, the current i m 

 in the multiplier could be calculated in absolute measure. Fi- 

 nally, from the known resistances of M, S, and B the whole mag- 

 netizing current i in P was obtained. 



E 



Now, with respect to the quantity — required for the calcula- 



tion of Jc } it is easily seen that it becomes =w b ~, if w b denotes 



the absolute resistance of the bridge B, and J m the integral value 

 of the induction-current in the multiplier. (It is here presup- 

 posed that w b z may be neglected in comparison with the product 

 of the two resistances K B P and S B M, which was admissible 

 in all the experiments.) 



As a bridge B strong copper wires were used, each with its 

 ends soldered to two small forks of thicker wire, which were 

 amalgamated beneath and dipped into mercury-cups (fig. 5). 

 The resistance of the proper wire 1B2 (from the place of solder- 

 ing, 1, to the other, 2) is to be regarded as the quantity denoted 



