1895.] Straws in the Testing of Materials and Structures. 135 



The tendency to creep has now practically disappeared so far as 

 this range of load is concerned ; the strain is very nearly proportional 

 to the stress, and there is no set. It will be remembered that 6 tons 

 was the greatest load formerly applied, and that it brought the piece 

 to the yield-point in the original test. 



The loading was then resumed, and was carried a stage farther to 

 see how far the new yield-point would be above the old one. 



Load in tons. Extensonieter. Difference per ton. 



200 



1 290 96 



2 393 97 



3 490, 97 



4 588 98 



5 685 97 



6 782 97 

 6| 832 



7 908 Creeping, at first slow, then 



faster, and tending to run 

 off the scale. 



. 600 Showing 400 divisions, or 



0*008 inch, of further per- 

 manent extension. 



The zero of the extensometer was now brought back to 200, and the 

 loading was immediately repeated, to see whether this small amount 

 of further overstrain had undone, to any extent, the molecular 

 settlement which had been going on during the 5 days of rest. 



Load in tons. Extensometer. Difference per ton. 



. 200 



1 297 97 



2 395 98 



3 492 97 



4 591 99 



5 692 101 



6 793 101 



204 Creeping back to 202, but not 



further. 



It is clear from these figures that the elasticity has again been, 

 to some extent, injured by the overstrain at the 7- ton load, small as 

 that was ; and one effect is that even a load of 6 tons now produces 

 some persistent set. 



The following are values of Young's modulus E, for this bar, 

 calculated from the foregoing experiments (3A, 3e, and 3c). 



