he water withdrawn; the action at a
distance would then cease, and, as far as the sense of touch is
concerned, the wader would be first rendered conscious of the motion
of the wheel by the blow of the paddles. The transference of motion
from the paddles to the water is mechanically similar to the
transference of molecular motion from the heated body to the aether;
and the propagation of waves through the liquid is mechanically
similar to the propagation of light and radiant heat.

As far as our knowledge of space extends, we are to conceive it as the
holder of the luminiferous aether, through which are interspersed, at
enormous distances apart, the ponderous nuclei of the stars.
Associated with the star that most concerns us we have a group of dark
planetary masses revolving at various distances round it, each again
rotating on its own axis; and, finally, associated with some of these
planets we have dark bodies of minor note--the moons. Whether the
other fixed stars have similar planetary companions or not is to us a
matter of pure conjecture, which may or may not enter into our
conception of the universe. But probably every thoughtful person
believes, with regard to those distant suns, that there is, in space,
something besides our system on which they shine.

From this general view of the present condition of space, and of the
bodies contained in it, we pass to the enquiry whether things were so
created at the beginning. Was space furnished at once, by the fiat of
Omnipotence, with these burning orbs? In presence of the revelations
of science this view is fading more and more. Behind the orbs, we now
discern the nebulae from which they have been condensed. And without
going so far back as the nebulae, the man of science can prove that
out of common non-luminous matter this whole pomp of stars might have
been evolved.

The law of gravitation enunciated by Newton is, that every particle of
matter in the universe attracts every other particle with a force
which diminishes as the square of the distance increases. Thus the
sun and the earth mutually pull each other; thus the earth and the
moon are kept in company, the force which holds every respective pair
of masses together being the integrated force of their component
parts. Under the operation of this force a stone falls to the ground
and is warmed by the shock; under its operation meteors plunge into
our atmosphere mid rise to incandescence. Showers of s