re to pass through the same stages and wonderful transformations to
which our own planet has already been subjected. All that has occurred
with respect to this earth, and the system of which it forms a part, is
but a type of what is constantly going on in the countless other systems
of stars that people the firmament.
The first stage in the history of these fiery particles is the formation
among them, in some unaccountable way, of nuclei, or centres of
aggregation, like the bright points that are now visible in some of the
nebulae of the heavens. As soon as these centres are formed, gravity, one
of the original principles of matter, begins to act, and the atoms in
all the neighbouring parts of space are attracted towards the nucleus
and heaped upon it. In this manner, a central sun of vast dimensions is
formed, which soon assumes a motion of rotation upon its axis from the
general law which gives a circular movement to all fluids that are drawn
towards a common centre. The centrifugal force thus generated tends to
throw off matter from the equatorial regions of the great orb, but is
restrained by the attraction of gravitation, which would prevent any
separation of the parts, if the sun itself did not now begin to cool
down, and consequently to shrink in size. Under this cooling process, a
crust is formed upon the surface, too rigid to yield to the force of
gravity, and the parts within, continuing to shrink, separate from this
envelope; so that there is now a central orb, revolving more rapidly
from its greater density and smaller diameter, and surrounded by an
exterior shell, or band, like Saturn's ring, rotating at its original
speed. As we cannot suppose that the ring would usually be of uniform
thickness and strength, it eventually breaks up into fragments, the
larger of which attracts the smaller into itself, and the whole is
formed by its revolving motion into an oblate spheroid circling round
the contracted sun in the centre. In this manner, the planet Uranus was
shelled off from our sun, which originally filled the whole of the vast
sphere, of which the distance from Uranus to the centre of the present
sun is but the radius. The planet itself, by the same process of
cooling, shrinking, and thus forming exterior rings, threw off
successively all its six satellites; and the sun, also, continuing to
contract from the loss of heat, formed another ring, and thus
constituted the planet Saturn. In this way were formed
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