At the present stage of the metal‐working industry the treatment of metals by pressure is one of the most important technological processes. Further development of technique will, no doubt, only increase the significance of this process. It must be stated, however, that the working of metals by pressure has as yet no strictly scientific basis. The theory of the mechanics of the plastic deformation of bodies, on which the working of metals by pressure is based, finds itself in the initial phase of its development and is far from being in a state where we can guide ourselves by it directly in our industrial work.