a displacement of the negative mass of the inequality, i.e., of the grains absent, and in whatever new direction the surface is propagating, the motion of the medium, outside the surface, is such as represents equal and opposite momentum, as when a bubble rises in water.
And in the same way for the inequality resulting from an excess of grains, the momentum would be positive.
11. The principal stresses in the medium.
The principal stresses outside the singular surface of a negative inequality are to a first approximation.
Two equal tangential pressures equal to 65 of the mean pressure in the medium, and a normal pressure equal to 35 of the mean pressure in the medium. The resultant of the pressures being everywhere equal to the mean pressure of the medium.
12. The cause of gravitation.
We have now sketched the structure of the inequalities, where inequalities exist, as resulting from the presence or absence of grains, the permanence of the singular surfaces, and their freedom of motion by propagation, and have
