the opposite direction to that of the motion of the grains, or balls, in strained normal piling by the diameter of a ball.
And in the same way for each of the remaining five balls, each grain as it comes down causes the nucleus to advance by a diameter in the opposite direction to that ball. Fig. 7 shows the action in progress when there have been four encounters. Three balls have disappeared into the basket, and one is on its way to the basket; the nucleus has advanced four diameters. One ball is still on the upper chase, while another is on the steep slope.
Then, when the inequalities are such as result from an absence of grains, the singular surfaces correspond to the molecules of matter.
It may help in the formation of a conception if we recall Lord Kelvin's theory of vortex atoms which promised so much, and afforded the first conception of matter passing through a space completely occupied by matter without resistance. In that theory the vortex ring, in which the displacement is from the inside, was the instrument, so to speak, that was to secure the free motion of matter through the medium. This theory has been found intractable, and is now shown to be impossible. But in its place we
