her,
as we have seen is the case, on account of its being gravitative. I will
also prove later on, that Herschel was right with regard to the
resistance of the motion of comets through it. Then he refers to its
particles probably possessing inertia, as though he had anticipated the
atomicity of the Aether, and assuming that atomicity, he was compelled
to postulate inertia also as we have done in Art. 48.

Lastly, he points out that each separate particle must have its own
plane of motion, its own orbit, and its periodic time. Now this view
fully coincides with that laid down in this article, where we have
learned that the rotating Aether has its own plane of motion, that plane
being the Plane of the Ecliptic, and as every particle or atom has its
allotted place in the rotating Aether, then, as Herschel points out, the
particle must have its own orbit, and plane of motion, and also its own
periodic time. If, therefore, we had desired fuller confirmation of this
atomic gravitating Aether, we could not have wished for more conclusive
proof than that given by one of the greatest philosophical astronomers
of the last century. We shall see later that Herschel also had a clearer
view of cometary phenomena, and of the forces which played a part in
those phenomena, than any of his contemporaries, when we deal with the
origin and motions of all comets. Thus from Herschel we learn that the
zodiacal light is caused by the atomic, gravitating, and rotatory Aether
as that aetherial medium revolves round the sun, while at the same time
every atom of the medium is itself in a state of rotation on its axis,
as it performs its journey in its own orbit and in its own plane of
motion.

ART. 110. _Centripetal Force._--We have now to consider what is the
physical cause of that part of the compound Law of Gravitation known as
the Centripetal Force. As we have already learned (Art. 10), this force
is really none other than the Attractive Force of Gravitation, in that
its mode of operation always acts towards the centre of the attracting
body, and hence was called by Newton the Centripetal Force.

The centripetal force is, however, the exact counterpart and complement
of the centrifugal force, in the same way that the latter is the exact
counterpart of the former, as we have already learned that the
centrifugal force operates along the same path, and that it is subject
to the same law of proportion, being equal to the product of the masses