upon the Dimensions of Iron and Steel Bars. 233 



the point of saturation, on account of the magnetism being in 

 that case nearly proportional to the intensity of the current. 

 For the same reason, on examination of the previous tables, 

 it will be found that the elongation is, below the point of satu- 

 ration, very nearly proportional to the magnetism multiplied 

 by the current. The necessity of changing the law arises 

 from the iact that the elongation ceases to increase after the 

 iron is fully saturated ; whereas the shortening effect still 

 continues to be augmented with the increase of the intensity 

 of the current. 



Experiment 16. Same wire. +0*5 magnetism to begin 

 with. Tension lOiO lbs. 



