XLII. DISCUSSION. 
“standardising limit of elasticity ” the point of intersection of the 
stress diagram with a line making an angle with the axis of stress 
whose tangent was 5°/ greater than that due to the rectilinear 
portion of the diagram. 
Such a point was exceedingly easy of determination and always 
lay between the true elastic limit and the yield point; being 
sufficiently near the former in. most cases to ensure that the 
rate of elongation was not more than 5% above its normal value. 
All difficulties as regards errors of observation would practically 
be removed, and he was of opinion that such a “ limit” would be 
found very uniform in all tests from the same bars, and sufficiently 
near the commencement of the plastic action for all engineering 
purposes. Such astandard limit would be fair both to the engineer 
and the manufacturer, and probably prevent materials from being 
unfairly condemned. He had known materials rejected by one 
engineer as bad and accepted by another as of good quality, simply 
through a descrepancy in the tests. 
He had applied his proposed “ standardising limit ” method to 
the test of the bar of basic ingot iron given in the paper in illus- 
tration of Tetmaier’s system of recording a test, by plotting the 
figures with the result shewn in the diagram. 
Fig. 1. 
OX = Loadin“ Tonnes.” OY - entage oer 
fe = pearent limit of Elasticity a aie to Tetmaier. 
B = Standardising limit of Elasticity. (Selman } 
C = Yield Point. 
