Crook — Electromagnetic Alternating Currents. Ill 



The effect due to a direct current of varying current density 

 is shown in Diagram YI. The direct current was applied by 

 suddenly closing the circuit through the iron. A slow build- 

 ing up of the current had no effect on the residual magnetism. 



DiaQ-ram V. 



This shows that the effect was due to the sudden impulse of 

 the current through the copper rod or through the iron. 

 Readings for these curves are given in Table 6. 



Am. Jour. Scl— Fourth Series, Vol. XIV, Xo. 80.— August, 1902. 

 10 



