202 



20 



30 



4D 



Copper Cylinder. 



Curve 11 shows the rate of decay of the total induction 

 through a copper cyhnder 1 -875cm. in diameter. The close 

 agreement between the theoretical and experimental curves is 

 a confirmation of the mathematical theory, for the difference 

 between the two is quite within the limits of experimental 

 error. The induction falls rapidly at first, and then very 

 slowly, so that a long interval elapses before the induction 



the induction has fallen to half its original 



has fully fallen. 



In 0-00074sec. 

 value. 



Soft-iron Cylinders. 



Curve 12 shows the rate of decay of induction in soft-iron 

 cylinders of diameter 0-676cm. and 0-573cm. respectively. 

 The rate of decay is much slower than in the case of copper, 

 on account of the high permeability of the iron, although the 

 diameter and conductivity are less for the iron than the 

 copper. 



