THE THERMO-ELECTRIClEFFECTS OF LONGITUDINAL STRESS IN IRON. 45 



states of the metal after it is tapped when we are going through the 

 " on " branch, and the other two (I) and d) when we are going 

 through the " off" branch.. The effect of agitation would be to bring 



Load 



the molecules of the metal into altered configurations by making 

 them lock into each other and come closer together, the accumulated 

 hysteresis, if there be any, being thus shaken out. In the present 

 case, therefore, the effect of pulling or relaxing on the change of 

 E. M. F. may be considered to come out unmasked. The changes of 

 E. M. F. as represented in the above figures may be regarded as the 

 proper effects of mechanical actions upon the iron in stable conditions. 



§ 22. With respect to the iron under stress and not subjected 

 to agitation, experiments have brought forth some quite different 

 features in the initial effects of application and removal of load. Four 

 cases which correspond to the above enumerated are shown in the 

 annexed figures. 



The difference between this and the preceding classes consists in 



