has in the kinetic theory of gases, secured for it immediately an
independent solidity and importance as a chemical theory when he first
promulgated it, to which it might even by this time scarcely have attained
if it had first been suggested as a probability indicated by the kinetic
theory of gases, and been only afterward confirmed by observation. Now,
however, guided by the views which Clausius and Williamson have given us of
the continuous interchange of partners between the compound molecules
constituting chemical compounds in the gaseous state, we see in Deville's
theory of dissociation a point of contact of the most transcendent interest
between the chemical and physical lines of scientific progress.

To return to elasticity: if we could make out of matter devoid of
elasticity a combined system of relatively moving parts which, in virtue of
motion, has the essential characteristics of an elastic body, this would
surely be, if not positively a step in the kinetic theory of matter, at
least a fingerpost pointing a way which we may hope will lead to a kinetic
theory of matter. Now this, as I have already shown,[1] we can do in
several ways. In the case of the last of the communications referred to, of
which only the title has hitherto been published, I showed that, from the
mathematical investigation of a gyrostatically dominated combination
contained in the passage of Thomson and Tait's "Natural Philosophy"
referred to, it follows that any ideal system of material particles, acting
on one another mutually through massless connecting springs, may be
perfectly imitated in a model consisting of rigid links jointed together,
and having rapidly rotating fly wheels pivoted on some or on all of the
links. The imitation is not confined to cases of equilibrium. It holds also
for vibration produced by disturbing the system infinitesimally from a
position of stable equilibrium and leaving it to itself. Thus we may make a
gyrostatic system such that it is in equilibrium under the influence of
certain positive forces applied to different points of this system; all the