least all space to which
Gravitation extends, _including the sun and its system_, for Gravitation
is a property of matter dependable on a certain Force, and it is this
Force which constitutes matter." As the Aether fills all space,
including the solar system, therefore, according to Faraday, "Aether
must also be Matter."

By the hypothesis that Aether is matter, with all the properties that
such a hypothesis logically gives to Aether, I venture to premise that
the third Rule of Philosophy will be fulfilled, and that there is no
phenomenon of the astronomical world, and no part of the universal Law
of Gravitation which such a hypothesis will fail to account for on a
satisfactory physical basis. For the first time a physical explanation
will be given to Newton's Laws of Motion, at least to those laws which
are strictly in accordance with the first and second Rules of
Philosophy. For the first time a physical conception will be given to
all Kepler's Laws, and what the mathematical Laws of Gravitation have
done to Kepler's Laws, in giving them a mathematical basis, the simple
hypothesis that Aether is matter, with all that is logically involved
therein, will do for the same laws from the physical standpoint. For the
first time a physical conception will be given to the Centrifugal and
Centripetal Forces, which are the complement and the counterpart of each
other, that physical conception being the outcome of the same hypothesis
that Aether is matter.

In addition to this, light is thrown upon such problems as are referred
to by Lord Kelvin (_Phil. Mag._, July 1902) in his paper on "Clouds on
the Undulatory Theory of Light," and further light is given to some
theories of Electricity advanced by such men as Faraday, Clerk Maxwell,
and Professor Thompson. I venture to think, therefore, that the
hypothesis advanced, and the conception put forward that Aether is
matter, is philosophically correct, and is warranted by the results that
arise out of such a hypothesis.

It may be thought by some that the hypothesis that I have advanced is
already conceded, and that the fact that Aether is matter is already
admitted by scientists and advanced thinkers generally. But such an idea
is only partly correct. It is already admitted by some of our most
advanced scientists that Aether is matter, but that admission is only
carried partially to its logical conclusion.

Lord Kelvin in an address to the British Association, 1901, gave
utter