12 Foster, Phenomena due to Repetitions of Stress. 



The question as to whether a metal can be restored' 

 after being subjected to a number of repetitions of stress 

 requires further careful investigation, Ewing (" Strength 

 of Materials," p. 56) states that " annealing in any case 

 " serves to cure fatigue and restores the primitive quality 

 " of the piece in respect of both strength and elasticity." 



2.000- 



\- 



3 

 Z 



/.ooo - 



200,000 400.000 600,000 800,000 



REPEnnONS (stress RANCE = 21 TONS a"j 



Fig. 6. 

 Mr. Smith states that his results on this point are how- 

 ever so discordant that they have not been published. 

 Probably Ewing's statement is founded on practical ex- 

 perience, in which case probably the stresses would in many 



