Note Return to text — EXPERIMENTS ON RETAINING WALLS AND PRESSURES ON TUNNELS.

It is a question too, whether, as is the case with loosely granular materials, friction acts (before rupture) at the same time with shear or cohesion in consolidated earth. From the interesting remarks[Footnote 11] of Mansfield Merriman, M. Am. Soc. C. E., on internal friction, it seems probable that friction and shear exist at the same time in a solid; but, to reach sound conclusions, as he states, “further studies on internal friction and on internal molecular forces are absolutely necessary.”