274 Prof. J. A. Ewiog. [June 20, 



Fig. 2. 



on p. 273, the equivalent effect of the compensating coil being added 

 in each case to the actual magnetometer readings. 



In fig. 2, curves are drawn to show the relation of the current to 

 (a) the immediate magnetisation; (b) the magnetism after 5 seconds; 

 and (c) the magnetism after 1 minute. The gradient of the curve 

 (a) at and near the origin is the same as that of the corresponding 

 curve in fig. 1, when allowance is made for difference of scales. In 

 the present instance one division of current is 0*0013 of p, and 

 one division of magnetism is 0'008 of f. The gradient begins to 

 increase very sensibly when p exceeds about 0*07. 



Some of the results of Table I are also shown in fig. 3, which gives 

 time curves of the growth of magnetism for the first two stages 

 (currents 27 and 62). Similar curves for the other stages may readily 

 be constructed from the table. It should be noticed that the time 



