as suggested in this work, we shall seek to show that Newton's
Second Law of Motion holds good in its application to the new theory.
With the present conception of a frictionless Aether, however, it is
philosophically impossible for the Aether to exert force on any body
that may exist in it. Because, to the extent that it is frictionless, to
that extent it ceases to possess mass. If it does possess mass, then it
cannot be frictionless. Such an assumption violates all the Rules of
Philosophy.

Yet the Aether is supposed, in some unknown manner, to possess inertia,
which property is also dependent on mass. If the Aether really possesses
inertia, then it must possess mass, and possessing mass it ceases to be
a frictionless medium. So that if it possesses mass, then it can exert
force the same as any other body, and Newton's Second Law of Motion is
applicable to it.

ART. 16. _Third Law of Motion._--Newton's Third Law of Motion reads as
follows--

"Action and re-action are equal and opposite, or, to every action there
is always an equal and contrary re-action." This law is also conformable
to experience; for, by experiment, it has been proved to hold good for
electric and magnetic action. As MacLaurin points out, the Third Law of
Motion may be extended to all sorts of powers that take place in Nature,
and belongs to attraction and repulsion of all kinds, and must not be
considered as being arbitrarily introduced by Newton.

The mutual action between any two bodies has, therefore, a double
action. Thus a piece of stretched string must be conceived as pulling at
both ends; the pull at the one end being exactly equal and opposite to
the pull on the other end.

A magnet will attract a piece of iron with a certain force, but it is
equally true that the iron attracts the magnet with an exactly equal and
opposite force. We might even extend the application of this Third Law
to a falling stone in its relation to the earth. Thus, if a stone is
dropped from a high altitude to the surface of the earth, although the
motion seems to be all in one direction, yet if the Third Law holds
good, then the earth is attracted by the stone in exactly an equal, but
opposite direction, to that in which the earth attracts the stone.

As, however, the mass of the earth is very great compared with that of
the stone, it follows that the velocity of the stone compared with the
velocity of the earth, must be very much greater, in order that the