he universe
are identical with such as we are familiar with, and that elsewhere the
variety is as great. The qualities of the elements, within a certain
range of temperature, are permanent; they are not subject to
fluctuations, though the qualities of combinations of them may vary
indefinitely. The elements therefore may be regarded as retaining their
identity in all ordinary experience.

THE ETHER IS HOMOGENEOUS.

One part of the ether is precisely like any other part everywhere and
always, and there are no such distinctions in it as correspond with the
elemental forms of matter.

4. MATTER IS ATOMIC.

There is an ultimate particle of each one of the elements which is
practically absolute and known as an atom. The atom retains its identity
through all combinations and processes. It may be here or there, move
fast or slow, but its atomic form persists.

THE ETHER IS NON-ATOMIC.

One might infer, from what has already been said about continuity, that
the ether could not be constituted of separable particles like masses of
matter; for no matter how minute they might be, there would be
interspaces and unoccupied spaces which would present us with phenomena
which have never been seen. It is the general consensus of opinion
among those who have studied the subject that the ether is not atomic in
structure.

5. MATTER HAS DEFINITE STRUCTURE.

Every atom of every element is so like every other atom of the same
element as to exhibit the same characteristics, size, weight, chemical
activity, vibratory rate, etc., and it is thus shown conclusively that
the structural form of the elemental particles is the same for each
element, for such characteristic reactions as they exhibit could hardly
be if they were mechanically unlike.

Of what form the atoms of an element may be is not very definitely
known. The earlier philosophers assumed them to be hard round particles,
but later thinkers have concluded that atoms of such a character are
highly improbable, for they could not exhibit in this case the
properties which the elements do exhibit. They have therefore dismissed
such a conception from consideration. In place of this hypothesis has
been substituted a very different idea, namely, that an atom is a
vortex-ring[1] of ether floating in the ether, as a smoke-ring puffed
out by a locomotive in still air may float in the air and show various
phenomena.

[Footnote 1: Vortex-rings for illustration may be made by hav