contemplating such an hypothesis; yet [it is] no more than the
observed phenomena of light and heat force us to accept. We
cannot deny even the strange suggestion of Dr. Young, that there
may be independent worlds, some possibly existing in different
parts of space, but others perhaps pervading each other, unseen
and unknown, in the same space. For if we are bound to admit the
conception of this adamantine firmament, it is equally easy to
admit a plurality of such."

[4] Jevons's Principles of Science, Vol. II. p. 145. The figures,
which in the English system of numeration read as seventeen
billions, would in the American system read as seventeen
trillions.


The ether, therefore, is unlike any of the forms of matter which
we can weigh and measure. In some respects it resembles a fluid,
in some respects a solid. It is both hard and elastic to an
almost inconceivable degree. It fills all material bodies like a
sea in which the atoms of the material bodies are as islands, and
it occupies the whole of what we call empty space. It is so
sensitive that a disturbance in any part of it causes a "tremour
which is felt on the surface of countless worlds." Our old
experiences of matter give us no account of any substance like
this; yet the undulatory theory of light obliges us to admit such
a substance, and that theory is as well established as the theory
of gravitation. Obviously we have here an enlargement of our
experience of matter. The analysis of the phenomena of light and
radiant heat has brought us into mental relations with matter in
a different state from any in which we previously knew it. For