LAPLACE was the first to suggest the nebular hypothesis, which he did
with great diffidence, not as a theory proved, or hardly likely, but as
a mathematical possibility or illustration. His range of creation,
moreover, was not so vast as that of our author, which assumes to
compass the entire universe, but was limited to the evolution of the
solar system. The mode in which this might be evolved, LAPLACE thus
explains:--

He conjectures that in the original condition of the solar system the
sun revolved upon his axis, surrounded by an atmosphere which, in virtue
of an excessive heat, extended far beyond the orbits of all the planets,
the planets as yet having no existence. The heat gradually diminished,
and as the solar atmosphere contracted by cooling, the rapidity of its
rotation increased by the laws of rotatory motion, and an exterior zone
of vapour was detached from the rest, the central attraction being no
longer able to overcome the increased centrifugal force. The zone of
vapour might in some cases retain its form, as we still see in Saturn's
ring; but more usually the ring of vapour would break into several
masses, and these would generally coalesce into one mass, which would
revolve about the sun. Such portions of the solar atmosphere abandoned
successively at different distances, would form planets in the state of
vapour. These masses of vapour, it appears from mechanical laws, would
have each its rotatory motion, and as the cooling of the vapour still
went on, would each produce a planet that might have satellites and
rings formed from the planet, in the same manner as the planets were
formed from the atmosphere of the sun.

All the known motions of the solar system are consistent and
reconcileable with this theory of LAPLACE, and upon it the author of the
_Vestiges_ has enlarged and founded his wider scheme of physical