Crook — Electromagnetic Alternating Currents. 137 



represent current density per sq. mm. Curve 1 shows the 

 effect due to a constant current ; curve 2, that due to an alter- 

 nating current. 



Diagrams II and III. 



Curve 1 (Diasjram III) shows the reduction of the residual 

 magnetism due to an alternating current of varying density 

 passing through the iron strips in series. 



