A suggested method is described, to provide data relating to the admissible strength of rocks in engineering. The calculated stress distribution in cylindrical specimens under uniaxial aand triaxial loading, and the deduced strain distribution in these specimens are shown to be useful working guides to the prediction of strength behaviour in the rocks concerned. A safe limit of strength may be specified by limiting the tensile strains so that the development of cracks will not occur. © 1969.