XXXV111. ABSTRACT OF PROCEEDINGS. 



the coal-measures on either side of it will obviously claim 

 the serious attention of those who in the future have charge 

 of coal mines in that portion of our coalfields. 



Remarks were made by Mr. O. A. Benbow and Mr. J. 0. 

 L. Rae. 



2. "Investigations in regard to the comparative strength 

 and elasticity of Portland cement mortar and concrete 

 when reinforced with steel rods and when not re- 

 inforced," by W. H. Warren, m. inst.cE., m. Am. soc. c e., 

 Ohallis Professor of Engineering, University of Sydney. 



The paper described experiments on various mortars and 

 concrete in tension and compression, also when subjected 

 to bending stresses. The extensions, shortenings and 

 deflections were accurately determined by means of 

 Marten's mirror apparatus and sector deflectometers, and 

 the results plotted gave characteristic diagrams. Tension 

 — The extensions of the specimens subjected to direct 

 tension when reinforced with steel rods were considerably 

 less than occurred in similar specimens not reinforced, the 

 stress-strain diagrams plotted from the observations taken 

 were all convex to the stress axis, but the curve was much 

 flatter for the reinforced specimens. The coefficient of 

 elasticity calculated from the stresses and elongations 

 decreased as the stress was increased. Compression — The 

 compression tests were made on prisms 12 inches by 6 inches 

 by 6 inches, and the coefficient of elasticity calculated as 

 in the tension tests. The curves representing the stresses 

 and shortenings of the prisms, were much flatter than in 

 the tension tests, and the coefficient of elasticity greater. 

 The coefficient of elasticity increases with the age and 

 richness of the mixture. Transverse tests — The transverse 

 tests consisted of experiments with beams reinforced on 

 the tension side with steel rods, compared with similar 

 beams not reinforced. Experiments were also made on 



