From this it follows that, as v approaches -J (incompressible body), the observed rupture stress may be much less than the theoretical stress. Although (in view of the asymmetry of the method with respect to stresses and deformations) this cannot be regarded as a new explanation of the sharp difference between the theoretical and observed rupture stresses, a more critical approach is necessary to existing calculations of theoretical stress with regard to interactions not coinciding with the direction of rupture.