bounded by the solar system; but even the solar system
presented itself under an aspect strangely different from what it now
wears. It consisted of the sun, seven planets, and twice as many
satellites, all circling harmoniously in obedience to a universal law,
by the compensating action of which the indefinite stability of their
mutual relations was secured. The occasional incursion of a comet, or
the periodical presence of a single such wanderer chained down from
escape to outer space by planetary attraction, availed nothing to impair
the symmetry of the majestic spectacle.

Now, not alone the ascertained limits of the system have been widened by
a thousand millions of miles, with the addition of one more giant planet
and seven satellites to the ancient classes of its members, but a
complexity has been given to its constitution baffling description or
thought. Five hundred circulating planetary bodies bridge the gap
between Jupiter and Mars, the complete investigation of the movements of
any one of which would overtask the energies of a lifetime. Meteorites,
strangers, apparently, to the fundamental ordering of the solar
household, swarm, nevertheless, by millions in every cranny of its
space, returning at regular intervals like the comets so singularly
associated with them, or sweeping across it with hyperbolic velocities,
brought, perhaps, from some distant star. And each of these cosmical
grains of dust has a theory far more complex than that of Jupiter; it
bears within it the secret of its origin, and fulfils a function in the
universe. The sun itself is no longer a semi-fabulous, fire-girt globe,
but the vast scene of the play of forces as yet imperfectly known to us,
offering a boundless field for the most arduous and inspiring
researches. Among the planets the widest variety in physical habitudes
is seen to prevail, and each is recognised as a world apart, inviting
inquiries which, to be effective, must necessarily be special and
detailed. Even our own moon threatens to break loose from the trammels
of calculation, and commits "errors" which sap the very foundations of
the lunar theory, and suggest the formidable necessity for its complete
revision. Nay, the steadfast earth has forfeited the implicit confidence
placed in it as a time-keeper, and questions relating to the stability
of the earth's axis and the constancy of the earth's rate of rotation
are among those which it behoves the future to answer. Everywhe