1889.] On Time-lag in the Magnetisation of Iron. 



275 



rate of creeping is by no means excessively great in the first instants 

 after contact is made ; it is on this fact indeed that the practicability 

 of the method depends. 



Fig. 3. 



Similar differences between the immediate and ultimate increments 

 of magnetism present themselves when the magnetising force is 

 increased step by step. In the following experiment the compensat- 

 ing coil was set so as to balance the immediate effect of a feeble 

 magnetising current. Then such a current was applied, and the 

 creeping up of the magnetism during 1 minute was observed. At 

 the end of the minute the current was increased by a small step, and 

 it was found that the compensation was still correct or very nearly 

 so : in other words that the immediate effect of this small increase of 

 magnetising force bore the same or very nearly the same proportion 



