so many other planetoids this theory cannot be maintained. According
to the nebular hypothesis, these bodies are the consolidated portions of
a nebulous ring which remained separate instead of having coalesced into
one mass so as to form a planet. The uniform condensation of the ring
would result in the formation of a multitude of small planets similar to
what are found between the orbits of Mars and Jupiter. In Saturn's ring
we have a remarkable instance of annular consolidation in which the form
of the ring has been preserved. The ring is believed to consist of
myriads of minute bodies, each of which travels in an orbit of its own
as it pursues its path round the planet; the close approximation and
exceeding minuteness of those moving objects create the appearance of a
solid continuous ring.

Though, by means of the nebular hypothesis, it is impossible to explain
all the phenomena associated with the motions of the orbs which enter
into the structure of the solar system, yet this does not detract much
from the merits of the theory, the fundamental principles of which are
based upon the evolution of the solar system from a rotating nebula.
The retrograde motions of the satellites of Uranus and Neptune, the
velocity of the inner Martian moon, and other abnormalities in the
system, have not as yet been explained, but doubtless there are reasons
by which those peculiarities can be accounted for if they were only
known, '_felix qui potuit cognoscere causas omnium rerum_.'

No attempt has been made to supplant the nebular hypothesis by any other
theory of cosmical evolution. Modern investigations and discoveries have
strengthened its position, and at present it is the only means by which
we can account for the existence of the visible material universe by
which we are surrounded.

In the days when Milton lived--three hundred years ago--the nocturnal
heavens presented the same appearance to an observer as they do at the
present time. The stars pursued their identical paths, and looked down
upon the Earth with the same aspect of serene tranquillity, regardless
of the vicissitudes which affect the inhabitants of this terrestrial
sphere. The constellations that adorn the celestial vault duly appeared
in their seasons,

and in the ascending scale
Of Heaven the stars that usher evening rose.--iv. 354-55.

The winter glories of Orion, the scintillating brilliancy of Sirius, and
the spangled firmament,