264 



Mr. 0. G. Lamb on the Distribution of 



the applied magnetizing force and the induction at the centre 

 of the bar ; we will refer to these as H a and Bo. 



The next step was to determine the curves of induction in the 

 bar; these are called set Q (figs. 3 and 4), and nine were taken 

 (numbered I. to IX.) at values of the magnetizing-current 

 giving values of H a shown in Table II. The points selected at 

 which to measure the induction were : as near the end as pos- 

 sible, 1, 2, 3, 4, 6, 8, 10, 12, 14, 16, 18, 20 inches from that 

 end, and at the centre (24 inches from end). A preliminary 



Fig. 3. 



30 

















































































































Q 







































































































































Centre 



22 



20 



16 14 12 10 



Distances from end in inches. 



experiment showed that either half of the bar gave closely 

 agreeing results at one definite value of H a . Several obser- 

 vations were taken at each point, and from the mean of these 

 the induction at each of the specified points was calculated as 

 a percentage of that which occurred at the centre : these 



