Two recent papers (Proc. I. Mech. E., 151, No. 2; 1944) deal with the properties of materials, and are of particular interest. "A Renaissance of Mechanical Properties", by Sq.-Leader A. C. Vivian, is a plea for clarity in the terms describing the mechanical properties of metals, and demonstrates the fallacy of calculating stresses on a nominal tbasis instead of actual cross-sectional areas. The fundamental relationship between the factors stress, strain, temperature and loading-rate is discussed in detail, and a system of symbols is suggested for defining exactly the various properties of metals. "The Significance of Tensile and other Mechanical Test Properties of Metals", by Dr. H. O. Neill, is a critical consideration of the conventional quantities obtained from the tensile test, dealing particularly with the measurement of work-hardening capacity and plasticity. Attention is given to the various methods of plotting the results of tensile tests which enable these properties to be evaluated, and numerical data are given. The discussions on both these papers are included.