re the impact. The more minute this nodal subdivision,
the less must be the tendency to give up part of the vibrational energy
into the shape of translational energy in the course of a collision; and I
think it is rigorously demonstrable that the whole translational energy
must ultimately become transformed into vibrational energy of higher and
higher nodal subdivisions if each molecule is a continuous elastic solid.
Let us, then, leave the kinetic theory of gases for a time with this
difficulty unsolved, in the hope that we or others after us may return to
it, armed with more knowledge of the properties of matter, and with sharper
mathematical weapons to cut through the barrier which at present hides from
us any view of the molecule itself, and of the effects other than mere
change of translational motion which it experiences in collision.

To explain the elasticity of a gas was the primary object of the kinetic
theory of gases. This object is only attainable by the assumption of an
elasticity more complex in character, and more difficult of explanation,
than the elasticity of gases--the elasticity of a solid. Thus, even if the
fatal fault in the theory, to which I have alluded, did not exist, and if
we could be perfectly satisfied with the kinetic theory of gases founded on
the collisions of elastic solid molecules, there would still be beyond it a
grander theory which need not be considered a chimerical object of
scientific ambition--to explain the elasticity of solids. But we may be
stopped when we commence to look in the direction of such a theory with the
cynical question, What do you mean by explaining a property of matter? As
to being stopped by any such question, all I can say is that if engineering
were to be all and to end all physical science, we should perforce be
content with merely finding properties of matter by observation, and using
them for practical purposes. But I am sure very few, if any, engineers are
practically satisfied with so narrow a view of their noble profession. They
must and do patiently observe, and discover by observation, properties of
matter and results of material combinations. But deeper questions are
always present, and always fraught with interest to the true engineer, and
he will be the last to give weight to any other objection to any attempt to
see below the surface of things than the practical question, Is it likely
to prove wholly futile? But now, instead of imagining the quest