MAGNETIC REACTIONS 



35 



cate the position of the edges of the magnet pole; thus G' is the "trailing 

 tip." The curves in heavy lines show the observed induction in gausses 

 at different angular velocities. The number of revolutions per minute 

 of the disk is indicated on each curve. To avoid confusion, the individual 

 observations are omitted, except in the case of one curve. The points for 



-40 



mm 



-20 







20 



40 



mm 



Fig. 15. Magnetic induction across air-gap. Direction of motion of disk is to right. 

 G, G' indicate position of edges of magnet poles. 



