Attraction was to be found in that aetherial medium
which pervaded all space.

If, therefore, we attempt to explain the physical cause of Gravitation
Attraction by the tensions of the universal Aether, we shall not only be
dealing with the subject from a philosophical standpoint, but we shall
solve the problem in that direction in which Professors Preston and
Lodge and other scientists have suggested we are to seek for the
solution. Professor Curry, in his _Theory of Electricity and Magnetism_,
page 406, states: "If we regard the luminiferous Aether, as defined by
Von Helmholtz's equations, as the given medium or transmitter of
so-called gravitating action, we are then able on the one hand to
interpret its longitudinal oscillations as gravitational waves
propagated through space with the given enormous velocity, and on the
other hand, to form some conception of the mysterious force of
Gravitation itself, for we can then conceive it as a medium stress
arising from a certain type of Aether oscillations, its longitudinal
ones, that pervade entire space."

Now in order for us to lead up to the physical cause of the centripetal
force, we must recall some of the facts already given with regard to
planetary and solar space. Thus we have learned that the sun is an
electro-magnet possessing its own magnetic field, with its lines of
force (Art. 88). We have also learned that all the planets are
electro-magnets, each possessing its own field with its lines of force
(Art. 91).

We have further seen that the cause of all this electro-magnetism is due
to the fact that electric currents are continually circulating round
each body, and by their conjoint action with the magnets there are
produced the electro-magnetic fields that are associated with each body
in the solar system. From this hypothesis we arrived at the conclusion,
that wherever there was Aether, there we found electricity, because of
the electro-magnetic basis which Aether possesses. This result is fully
confirmed by Maxwell's electro-magnetic theory of light (Art. 78), which
has been so fully experimentally demonstrated by Hertz. Indeed, in the
minds of several scientists there is a growing conviction that Aether
and Electricity are possibly one and the same substance.

Professor Lodge, in the work already referred to, in relation to this
hypothesis, writes in the preface to that book: "Crudely, one may say
that as heat is a form of energy, so electricity is a form