UNIFICATION OF METHODS IN TESTING MATERIALS. XLII. 
It would be seen that the apparent limit of elasticity as given 
by Tetmaier was about 9,000 kilogrammes, and the yield point 
about 13,000 kilogrammes; the standardised limit being about 
11,400 kilogrammes with a very slightly augmented rate of 
elongation above the normal value. These values in tons per 
Square inch were Tetmaier’s limit of elasticity about 11-3 tons, 
standardised limit of elasticity about 14-5 tons, and the yield point 
abopted by the author 16-7 tons. Mr. Selman was of opinion 
that the 11:3 tons was much too low. For similar iron a number 
of Bauschinger’s tests gave an average of about 13-5 to 14 tons 
per square inch, a result strikingly in accord with that given by 
the method proposed by himself. It was quite easy for inertia in 
the testing machine to give abnormal values near the elastic limit, 
and this may probably have been the case in the present instance. 
Tt would also be noted that the differences of elongation as given 
in the table referred to were very small and fairly regular, except 
at 6,000 kilos., until about 11,000 kilogrammes was reached when 
' there was evidence of the commencement of plasticity, the differ- 
ence being 2:16 against 1-68 for the previous loads. This also 
confirmed his contention. There were many other points in the 
paper open to discussion, but he regretted that he had not had 
sufficient time at his disposal to criticise them. 
Mr. SHaw said he would like to make afew remarks with 
. Tegard to the “impact test.” Prof. Warren makes use of copper 
cylinders for regulating the strength of blow. He had a drawing 
of a small testing machine he had designed some time ago, which 
might be of interest to some of the members. This was designed 
for testing steel cylinders subject to very high strains such as are 
used in ordnance. The ram shown was turned toa very accurate 
fit, and fitted with a copper bush, and had a chamber containing 
the main body of the water round this bush. At the base of the 
pedestal there was another ram sealed by a small copper disc 
which acted on the top of the copper cylinder. The copper 
cylinder was of known size, diameter and length—the weights 
were allowed to fall on the disc and it in turn acted on the 
