researches of such men as
Clerk Maxwell, Poynting, Thompson and Hertz, it has been proved that
electro-magnetic phenomena are due to this same medium.

Several different forms of Aether have been postulated by various
philosophers from time to time, but the only Aether that has survived,
is that which was first conceived by Huyghens to explain the phenomena
of Light, though it was Thomas Young who finally succeeded in placing
the conception of the Aether on a sound basis. Each discovery of science
has only strengthened the hypothesis and existence of the Aether, the
latest discovery, that of wireless telegraphy so successfully developed
by Signor Marconi, being attributed to the electro-magnetic properties
of this self-same Aether.

It has already been pointed out that Newton endeavoured to account for
Gravitation by the pressure of the Aether. If, therefore, Gravitation be
really due to this universal medium it becomes necessary to ask
ourselves, What are the properties and characteristic qualities of this
wonderful medium? What then is Aether, and what its properties?

It has already been pointed out in Art. 29 that Aether is matter. Such
an assumption is strictly in accordance with the Rules of Philosophy,
quoted in Chap. I.

Not only is this hypothesis a simple one, but it is also in accord with
all our experience and observation.

It is a simple supposition, because, unless Aether is assumed to be
matter, then, instead of the universe being composed of two classes of
things, matter and motion, we have to add a third class, which we call
Aether. It can be readily seen, that by the introduction of a third
class into the composition of the universe, such an addition, instead of
simplifying the constitution of the universe, adds greater complexity to
the same.

By accepting the hypothesis that Aether is matter, we do away with the
third class of essentials in the universe, and so reduce the number to
two classes. If we could go one step further, and prove that instead of
there being two classes of things in the universe, there was only one
group, and show that all material things, and all phenomena could come
under the head of either matter, or motion, then we should have reduced
the universe to the simplest conception possible. As, however, it is not
possible, at least in our present state of knowledge, for us to come to
this fundamental and simple hypothesis of unity for the entire universe,
we must accept th