Year: 1872

of matter in the universe attracts


every other particle with 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
force of their component
parts. Under the operation of this


force, stone falls to the ground


and is warmed by the shocS; under


its operation, meteors plunge into


our atmosphere and rise to incades-


cence. Showers of such doubtless


fall necessarily upon the sun. Act


ed on by this force, were it stopped


in its orbit to,morrow, the earth
would rush TowTTds and finally COM


bine with the sun. Heat would also
be developed by this collision, and
/ Mayer, Helmholtz, and Thomson


have calculated its amount It
would equal that produced sby the
combustion of more than 5000


worlds of solid coal, all this heat
being generated at the instant of
collision. In the attraction of grav
ity, therefore, acting upon non-lu-


minous matter, we have Il source of


heat more powerful than could be


derived from any terrestrial COM


bustion. And were the matter Of
the universe cast in cold detached


fragments into space, and there


abandoned to the mutual gravita-
tinn Of its own parts, the collision of
the fragments would in the end pro
dSce the fires of the stars.


The action of gravity upon mat
ter originally cold may in fact be
the origin of all hight and heat, and
the proximate source of such other
powers as are generated by light
and heat. But we have now to in
quire what is the light and what is
the heat thus produced This
question has already been answered
in a general way. Both light and


heat are modes of motion. Two
planets clash and come to rest; their
motion, considered as masses, is de-
stroyed, but it is really continued
as a motion of their ultimate parti-
cles. 1t is this motion, taken up by
the ether, and propagated through


it with velocity of $4,000 miles
a second, that comes to us as the
light and heat of suns and stars.
The atoms of hole body swing
with inconceivable rapidity, but this
power of vibration necessarily i'm
plies the operation of forces between
the atoms themselves. 1t reveals
to rs that while they are held to-
gether by one force, they are kept
asdnder by another, their position
at any moment depending on the
equilibrium of attraction and repul-
sion. The atoms are virtually con-
nected by elastic springs which op-
pose at the same time their--ap-
proach and their retreBt, but which
tolerate the vibration called heats.
When two bodies drawn together
by the force of gravity strike each
other, the intensity of the ultimate
vib-ation, or, in other words, the
amount of heat generated, is pro-
portiOnable to the Uisd UiUa destroy
ed by the collision. The molecular
motion once set up is instantly
shared with the ether, and diffused
by it throughout space


We on the earth's surface live
night and day in the midst of ethe-
real commotion. The medium is
never still; the cloud canopy above
us may be thick enough to shut out
the light of the stars, but this cano-
py is itself warm body, which ra-
dates motion through ether. The
earth also is warm, and sends its
heat pulses necessarily forth. 1t is
the waste of its molecular motion
in space that chills the earth upon a
clear night; it is the return of its
motion from the clouds which pre-
vents the earth's temperature on a
cloudy night from falling so low.
To the conception of space being
filled, we must, therefore, add the |
conception of its being in state of
incessant tremor. The sources of
vibration are the ponderable masses
of sae universe. Let us take sam
pie of these and examine it in de- |
tail. When we look to our planet /
we find it to be an aggregate of
solids, liquids, and gases. When
we look at any of these, we gener-
ally find it composed of still more
elementary parts. We learn, for
examples, that the water of our
rivers is formed by the union, in
definite proportions of two gases,
oxygen and hydrogen. We know
how to bring these constituents to-
gether, and to cause them to form
water: we also know how to ar alyze
the water, and recover from it its
two constituents. So, likewise, as
regards the solid portions of the
earth. Our chalk hills, for exam
pie, are formed by combination
of carbon, oxygen and calcium
These are elements, the union of
which, in definite proportions, has
resulted in the formation of chalk.
The f1ints within the chalk we know
to be a compound of oxygen and sill
icium, called silica; and our ordina-
ry clay is. for the most part, formed
by the silicium, oxygen, and the
well known light metal, aluminium.
By far the greater portion Of the
earth's crust is compounded of the
elementary substances mentioned in
these few lines.-IyndDH.