83 



The results are shown in Table III. These results show that the be- 

 havior of nickel steel under oversrrain is like to that of ordinary steel, 

 namely: 



Overstrain destroys the P-limit. and elevates the Y-limit. 



The P-limit may be restored by annealing for a few moments in a 

 bath above 212° F. The P-limit may be also restored by a period of rest. 

 By a process of overstrain and subsequent annealing-, the P-limit may be 

 elevated to nearly the ultimate strength. 



The decrease of diameter was also measured. The ratio of side con- 

 traction to longitudinal extension was found to be nearly 14. which is 

 the value of Poisson's ratio for this metal. 



TABLE I. 



Value of E. in 100,000 Units as Derived from Tests on Bars of Nickel Steel at 



Three Laboratories. 



