experiment as laid down not only by Newton but by every
true philosopher.

Therefore, that Aether can possess different degrees of density, is only
the logical outcome of the statement that Aether is matter, seeing that
such a statement without the shadow of a doubt must at least imply that
it is gravitative.

I need hardly point out, that it is much more philosophical to be able
to account for the density of the Aether in a reasonable and
philosophical manner, than simply to postulate for the Aether certain
properties and qualities, because certain phenomena demand the existence
of such properties.

The Aether has been such a hypothetical medium, that it has been easy to
postulate for it certain properties, if certain phenomena have demanded
the existence of those properties.

Thus if the Aether were required to be elastic, then elasticity was
postulated for it; if more elastic, then greater elasticity was added.
If density were demanded, then density was postulated, and if less or
more density, less or more density was given to it.

That method of speculation may be satisfactory up to a certain point,
but no one will admit that such a method is wholly philosophical. It
will be a far better method to adopt, if, in dealing with the universal
Aether, we can make it conform to certain recognized laws and
principles, and from the application of those well-known laws, be able
to infer the exact constitution of this space-filling Aether medium.

Now the question arises, if Aether is gravitative, what effect has the
Gravitation of any body, be it an atom, or a meteor or planet, sun or
star, upon the Aether in which it moves, and which surrounds it?

That we may have some light thrown upon the matter, I would like now to
take the reader to Newton's _Optics_, in order that he may give us his
opinion as to this property of density of the Aether. In his nineteenth
query Newton (_Optics_) asks this question--

"Is not this medium much rarer within the dense bodies of the sun,
stars, planets and comets than in the empty spaces between them, and in
passing from them to great distances, doth it not grow denser and denser
perpetually, and thereby cause the gravity of those great bodies towards
one another, and of their part towards the bodies, every body
endeavouring to go from the denser parts of the medium towards the
rarer?"

Here then we have given to us an indication of what is the possible
state of things in relation