produced
by it. The latter is called heat; no other form of motion than that is
properly called heat. It is this alone that represents temperature, the
rate and amplitude of such atomic and molecular vibrations as constitute
change, of form. Where molecules like those in a gas have some freedom
of movement between impacts, they bound away from each other with
varying velocities. The path of such motion may be long or short,
depending upon the density or compactness of the molecules, but such
changes in position are not heat for a molecule any more than the flight
of a musket ball is heat, though it may be transformed into heat on
striking the target.

This conception of heat as the rapid change in the form of atoms and
molecules, due to their elasticity, is a phenomenon peculiar to matter.
It implies a body possessing form that may be changed; elasticity, that
its changes may be periodic, and degrees of freedom that secure space
for the changes. Such a body may be heated. Its temperature will depend
upon the amplitude of such vibrations, and will be limited by the
maximum amplitude.

THE ETHER IS UNHEATABLE.

The translatory motion of a mass of matter, big or little, through the
ether, is not arrested in any degree so far as observed, but the
internal vibratory motion sets up waves in the ether, the ether absorbs
the energy, and the amplitude is continually lessened. The motion has
been transferred and transformed; transferred from matter to the ether,
and transformed from vibratory to waves travelling at the rate of
186,000 miles per second. The latter is not heat, but the result of
heat. With the ether constituted as described, such vibratory motion as
constitutes heat is impossible to it, and hence the characteristic of
heat-motion in it is impossible; it cannot therefore be heated. The
space between the earth and the sun may have any assignable amount of
energy in the form of ether waves or light, but not any temperature. One
might loosely say that the temperature of empty spaces was absolute
zero, but that would not be quite correct, for the idea of temperature
cannot properly be entertained as applicable to the ether. To say that
its temperature was absolute zero, would serve to imply that it might be
higher, which is inadmissible.

When energy has been transformed, the old name by which the energy was
called must be dropped. Ether cannot be heated.

16. MATTER IS INDESTRUCTIBLE.

This is commonly sai