g 



readings o 



Mi: .1. MI-IK ON THE KKC'OVKKY OK IHOX FUOM OVERSTRAIN. 



of the speci.nen was re-measuml and the mluoeil section determined The- 

 tl.,... re-applied, the lpehai was re-l<.ade,l. and 



The load was now removed, and during its removal the following three readings 

 were taken : 



Tons/inch 2 . 



Extensometer. 



20 



10 







830 

 477 



60 but diminishing slightly 

 with lapee of time 



The series of increasing differences shown in this second table plainly indicates a 

 change in the elastic state of the material. HOOKE'S law is no longer obeyed. 



This augmentation of the differences is, to some extent, associated with creeping, and 

 to a greater extent, the higher is the applied load. Thus it is essential, if consistent 

 results are to be obtained, that the interval of time which elapses between successive 

 readings should always be kept the same. If a pause had been allowed to occur after 

 the addition of any of the higher loads in this second table, then, owing to prolonged 

 creeping, a larger difference would have been obtained than is recorded above. On 

 proceeding with the loading, however, the immediately succeeding difference, or 

 ditVerences, would have been smaller than according to the table. For had there 

 been no interruption, part of the creeping which occurred during the pause would 

 have been recorded on the addition of the subsequent loads. 



