pposed to have sprung from to account for the wide
intervals between them. The matter separated through the growing excess
of centrifugal speed would have been cast off, not by rarely recurring
efforts, but continually, fragmentarily, _pari passu_ with condensation
and acceleration. Each wisp of nebula, as it found itself unduly
hurried, would have declared its independence, and set about revolving
and condensing on its own account. The result would have been a
meteoric, not a planetary system.

Moreover, it is a question whether the relative ages of the planets do
not follow an order just the reverse of that concluded by Laplace.
Professor Newcomb holds the opinion that the rings which eventually
constituted the planets divided from the main body of the nebula almost
simultaneously, priority, if there were any, being on the side of the
inner and smaller ones;[1167] while in M. Faye's cosmogony,[1168] the
retrograde motion of the systems formed by the two outer planets is
ascribed--on grounds, it is true, of dubious validity--to their
comparatively late origin.

This ingenious scheme was designed, not merely to complete, but to
supersede that of Laplace, which, undoubtedly, through the inclusion by
our system of oppositely directed rotations, forfeits its claim simply
and singly to account for the fundamental peculiarities of its
structure.

M. Faye's leading contention is that, under the circumstances assumed by
Laplace, not the two outer planets alone, but the whole company must
have been possessed of retrograde rotation. For they were formed--_ex
hypothesi_--after the sun; central condensation had reached an advanced
stage when the rings they were derived from separated; the principle of
inverse squares consequently held good, and Kepler's Laws were in full
operation. Now, particles circulating in obedience to these laws can
only--since their velocity decreases outward from the centre of
attraction--coalesce into a globe with a _backward_ axial movement. Nor
was Laplace blind to this flaw in his theory; but his effort to remove
it, though it passed muster for the best part of a century,[1169] was
scarcely successful. His planet-forming rings were made to rotate _all
in one piece_, their outer parts thus necessarily travelling at a
swifter linear rate than their inner parts, and eventually uniting,
equally of necessity, into a _forward_-spinning body. The strength of
cohesion involved may, however, safely be called