Several experiments were devised to find out whether it is possible to measure the internal shearing stresses in a compressed disc, and the conditions under which it is possible to do so. Equations are developed for analysing shear stresses parallel to planes of slip and distortion due to double and single slipping. The relationship between shear stress and amount of shear is found for tensile and for compression specimens, when slipping is confined to one plane. The experimental results in the two cases are identical. The fact that the component of force normal to plane of slip is a pressure in one case and a tension in the other makes no measurable difference to resistance to slipping for given amount of slip. During double slipping resistance to shear increases more rapidly for a given total amount of slipping than when all slip is confined to one plane. The experiments cover a large range and show that resistance to shear goes on increasing up to greatest amounts of distortion used.