214 Dr. S. P. Thompson and Mr. Miles Walker on 



Behind, that is to say on the side opposite the coil, there is 

 no effect in either case. 



Fig. 1. 



Fig. 2. 





It was thought interesting to ascertain how far effects of 

 this kind could be obtained in practice, using an ordinary 

 iron plate somewhat less than that required for the perfect 

 Case, For this purpose two similar solenoids were wound, 



