ical agent--that is, the Aether;
therefore, wherever we get heat and light, there, according to Professor
Tyndall's statement, we must have a resisting medium, and as Aether
fills all space, the resisting medium must fill all space. This is
perfectly in accord with our assumption that the Aether is gravitative
and possesses inertia--that is, the capacity to receive and to impart
motion, and being gravitative it possesses mass or weight, which is the
very quality necessary for the existence of a resisting medium.

[Footnote 9: _Heat, a Mode of Motion._]

[Footnote 10: _Heat, a Mode of Motion._]

ART. 63. _Heat is a Repulsive Motion._--Whatever be the particular
character of the vibratory motion of the Aether termed heat, there is
one fact regarding the same that is very patent and obvious to all; and
that is, that the vibratory motion of heat is essentially a repulsive
motion, or a motion from a centre and not one to a centre.

Professor Davy points this out (Art. 60) where he says of heat, "It may
with propriety be called a repulsive motion," while Professor Challis
(Art. 61) states that "Each atom is the centre of vibrations propagated
from it equally in all directions, which give rise to a repulsive action
on the surrounding atoms. This action (he adds) is the repulsion of heat
which keeps the individual atoms asunder."

There have been many experiments undertaken which go to prove that a
repulsive action between atoms and molecules is produced by heat. It has
been demonstrated that certain coloured rings, known as Newton's rings,
change their shape and position when the glasses between which they
appear are heated, thus indicating the presence of a repulsive power due
to the increased heat. If we consider the change of state that heat
induces in matter, as, for example, from solid to a liquid, or liquid to
a gaseous form, we are compelled to admit that heat possesses an
expanding and therefore a repulsive motion. It is almost an universal
law that heat expands and cold contracts, and the greater the heat
absorbed, the greater the expansion. In the case of a solid being
converted into a liquid, a much greater heat or repulsive motion is
required to separate the particles, on account of the power of cohesion
being greater in the solid than in the liquid. As Professor Tyndall[11]
states when dealing with the stability of matter from the molecular
standpoint: "Every atom is held apart from its neighbour by a force