the increased
density of the Aether near the body upon the elasticity of the Aether?

From the analogy of sound in air, we arrive at the conclusion that Boyle
and Marriotte's Law equally applies to the Aether, as it does to the
atmosphere of any planet. That is, if the temperature of any stratum or
layer of the Aether remains the same, then the elasticity of the
aetherial medium in that layer is proportionate to its density, so that
while the gravitating property of the Aether makes it denser nearest the
central body, the fact that the elasticity is proportionate to the
density, does not affect the transmission of any wave-motion.

[Footnote 6: _Phil. Trans._, 1802.]

ART. 48. _Aether possesses Inertia._--From Art. 40 we have seen that all
matter possesses inertia, inertia being that property of matter by which
it cannot of itself change its state of motion or of rest.

If Aether be matter, therefore, then it must also possess inertia. This
property of inertia is already postulated for Aether by scientists, and to
that extent is conformable to the Rules of Philosophy. Professor Tyndall,
with reference to the inertia of the Aether, writes: "The motion of
Aether communicated to material substances throws them into motion. It
must be therefore itself a substance. Aether is a substance endowed with
inertia, and capable, in accordance with the established laws of motion,
of imparting its motion to other substances."[7]

Again, Lord Kelvin in his Address to the British Association, 1901, on
the "Clustering of Gravitational Matter in any part of the Universe,"
states: "Aether we relegate to a distinct species of matter which has
inertia, etc." Aether, therefore, according to Tyndall, "is a substance
or medium endowed with inertia, and capable, in accordance with Newton's
Laws of Motion, of imparting its motion to other substances."

If, however, the Aether is frictionless, as has generally been supposed,
then it cannot possess inertia, because to the extent that a body
possesses inertia, to that extent it is opposed to being frictionless.

Inertia is really the equivalent of mass, or the amount of matter
measured by gravity, and if Aether possesses mass in any sense at all,
as it must do if it is matter, then, possessing mass or weight, it must
offer resistance to any body moving through it, and to that extent
cannot be frictionless. To suppose that the Aether is frictionless, and
yet possesses inertia, is to suppose