t and second Rules of
Philosophy, such a conception must be put away, and in its place a more
philosophical conception must be forthcoming, which is that Aether is
gravitative; then, upon such a logical and philosophical basis, I
venture to premise that the great problem which is still outstanding of
the cause of Gravitation, will remain outstanding no longer, and the
physical cause of all the movements of all celestial bodies will be put
upon a physical basis, in addition to a mathematical one.

If such a result can be arrived at by the logical and philosophical
conception of a gravitative Aether, then the three Rules of Philosophy
are fully satisfied, and the assumption of a gravitative Aether is
warranted on a strictly philosophical basis.

So that Thomas Young is strictly correct from a philosophical standpoint
in his fourth hypothesis, when he states: "That all material bodies have
an attraction for the aetherial medium, by means of which it is
accumulated within their substance and for a small distance around them
in a state of greater density but not greater elasticity." He is not,
however, correct when he states that though there is a greater density
near the body, there is not a greater elasticity, as such an assumption
is opposed to experiment and observation in relation to perfect gases,
as I shall show when dealing with the elasticity of the Aether.

Again, in view of the fact that the Aether is atomic, it can now be
easily understood how it may be subject to Gravitation. The very essence
of Gravitation is that atoms, or particles, attract each other. If there
were no particles, or atoms, it is obvious that there would be no
attraction, and therefore no Gravitation. Wherever, therefore, there are
to be found atoms of any kind or sort, whether they be atoms of
hydrogen, oxygen, silver or aetherial atoms, there the Law of
Gravitation holds good, and attraction between these atoms is to be
found. In other words, any substance which is atomic, is also
gravitative. Now Aether is atomic as has been shown, and therefore from
that standpoint it is also gravitative. It may, however, be objected
that the assumption of gravitative properties for the Aether is after
all but a speculation, and that Young's fourth hypothesis was only a
hypothesis, and that the gravitating properties of the aetherial medium
have never come within the scope of direct experiment, without which no
hypothesis can be fully accepted.

If suc