UNIFICATION OF METHODS IN TESTING MATERIALS. XIII. 
THz UNIFICATION or tHe METHODS or TESTING 
MATERIALS usep 1n CONSTRUCTION, anv tHE Pre- 
CAUTIONS NECESSARY IN THE ACCURATE DETERMINATIONS 
OF THE VARIOUS COEFFICIENTS OF STRENGTH AND ELASTICITY. 
By W. H. Warren, M. Inst.C.E., M. Am. Soc. C.E., Wh. Se., 
Challis Professor of Engineering, University of Sydney. 
[With Plates 1 and 2.] 
[Read before the Engineering Section of the Royal Society of N. 8. Wales, 
June 16, 1897.] 
THE importance of establishing a uniform system of tests for 
construction materials is now fully recognised in all civilized 
countries. In America an attempt has been recently made under 
the auspices of the Society of Mechanical Engineers, to secure the 
adoption of uniform methods of testing materials A similar 
attempt was also made about the same time in France, but prob- 
ably the most important Society established for this purpose is 
that which was originated by the late Prof. Bauschinger, which 
held its first meeting in Munich in 1884, under the title ‘‘ The 
International Union for the Unification of the Methods of Testing 
Materials.” The scope and importance of this society at present 
is due largely to the energy and ability of Prof. Tetmaier of Zurich, 
who was the president for last year, This year the meetings are 
to be held at Stockholm, and in the year 1900 they will be held in 
Paris. So far the matters dealt with are fundamentally important 
and have done much to place the testing of materials upon a 
& Scientific basis, 
The author proposes in future papers to publish the most 
important of the investigations made at the University Engineer- 
ing Laboratory on the materials of construction, so that this paper 
is intended to serve as an introduction to those which are to follow. 
It is proposed to consider the nature of the mechanical tests 
rather than the results obtained, and generally to deal with the 
