that the material molecule is some kind of knot or coagulation of
ether."[5]

[5] Fortnightly Review, June, 1875, p. 784.


Another interesting consequence of Sir William Thomson's pregnant
hypothesis is that the absolute hardness which has been
attributed to material atoms from the time of Lucretius downward
may be dispensed with. Somewhat in the same way that a loosely
suspended chain becomes rigid with rapid rotation, the hardness
and elasticity of the vortex-atom are explained as due to the
swift rotary motion of a soft and yielding fluid. So that the
vortex-atom is really indivisible, not by reason of its hardness
or solidity, but by reason of the indestructibleness of its
motion.

Supposing, now, that we adopt provisionally the vortex
theory,--the great power of which is well shown by the
consideration just mentioned,--we must not forget that it is
absolutely essential to the indestructibleness of the material
atom that the universal fluid in which it has an existence as a
vortex-ring should be entirely destitute of friction. Once admit
even the most infinitesimal amount of friction, while retaining
the conception of vortex-motion in a universal fluid, and the
whole case is so far altered that the material atom can no longer
be regarded as absolutely indestructible, but only as
indefinitely enduring. It may have been generated, in bygone
eternity, by a natural process of evolution, and in future
eternity may come to an end. Relatively to our powers of