of their masses, and inversely as the square of the distance
between them." This complete law, however, only holds good when the two
forces are in equilibrium.

With this conception of the universal law which governs all matter, the
harmony and stability of the universe becomes possible from the physical
standpoint. Apart from this conjoint working of the two forces or
motions, a physical explanation of Universal Gravitation is impossible,
as with one force operating only throughout the universe, ultimate
stability is inconceivable, and the harmony of the spheres might at any
time be suddenly destroyed.

With this conception of the universal law which governs all matter, the
great Law of Gravitation is brought into harmony with all experience and
observation. Look where we will, or at what we will, there we find
forces possessing a dual character, as we have already seen proved.
Professor Tyndall, as we have already learned (Art. 63), definitely
states that the stability of atomic systems is preserved by the
existence and operation of _two forces, one attractive and the other
repulsive_, and what is true of the atomic world is equally true of
solar or stellar worlds. Thus for the first time in this respect, our
philosophy agrees with our experience, and the true relation of the
centrifugal force or motion to the centripetal force is made manifest.
So that, wherever in the solar system the centripetal force or
Gravitation Attraction operates, there, with exactly equal intensity and
power, the aetherial centrifugal force operates, at the respective mean
distances of the planets and satellites, where the two forces are in
equilibrium.

If it were possible to conceive of a stationary solar system, then, by
the conjoint working of the two forces, it would be equally possible to
conceive of perfect stability and harmony existing between the
respective planets and satellites of that system while stationary.

Such a conception is altogether impossible in the present state of
Philosophy, as the stability of the system, with the old view of the
Centrifugal Force, is entirely dependent upon the motions of the
respective bodies in that system; and if such orbital motions could be
stayed, then the only physical conception possible would be, that every
planet and satellite, planetoid and meteor within the attractive force
of the central body, the sun, would be slowly but surely drawn to a
fiery death, as they would all ultimately