392 Mr. F. J. Smith on the Effects of Magnetism 



through the iron core while the coil was in circuit with the 

 galvanometer. 



23. Two similar cores (fig- 

 opposite, but the amount of 

 into the helix together, their 

 to the battery-circuit ; the 

 cores, but no indication of 

 galvanometer G, the effect o 

 that of the other. 



. 5), having their sense of torsion 

 torsion in each equal, were put 



ends A, D and B, C being joined 



current was passed through the 

 current was manifested by the 



f one core apparently cancelling 



Fiar. 5. 



^sssm 



24. While a current was passing through the iron core sub- 

 ject to torsional set, a couple, indicated by the arrows P Q, was 

 applied in the direction of the torsion of the core (fig. 6). 

 When the arm A was moved through 10°, suddenly a 

 deflexion of 400 was given by the galvanometer. The length 

 of the core was 50 centim., diam. 4 millim. The transient 

 current was reversed by reversing the sense of the couple. 

 Wlien I made this experiment I had not read the work of 



Fiar. 6. 



Wertheim, 1852. He produced the same effect in the same 

 way — with an iron rod, but not under initial torsional set as 

 was the case in my experiment. 



