some places clusters of them) are seen in the nebulous rings, while
one or two huge masses seem to give promise of transformation into
stellar bodies of unusual magnitude. I say ``rings'' because although
the loops encompassing the Andromeda Nebula have been called spirals
by those who wish utterly to demolish Laplace's hypothesis, yet they
are not manifestly such, as can be seen on comparing them with the
undoubted spirals of the Lord Rosse Nebula. They look quite as much
like circles or ellipses seen at an angle of, say, fifteen or twenty
degrees to their plane. If they are truly elliptical they accord
fairly well with Laplace's idea, except that the scale of magnitude is
stupendous, and if the Andromeda Nebula is to become a solar system it
will surpass ours in grandeur beyond all possibility of comparison.

There is one circumstance connected with the spiral nebulæ, and
conspicuous in the Andromeda Nebula on account of its brightness,
which makes the question of their origin still more puzzling; they all
show continuous spectra, which, as we have before remarked, indicate
that the mass from which the light comes is either solid or liquid, or
a gas under heavy pressure. Thus nebulæ fall into two classes: the
``white'' nebulæ, giving a continuous spectrum; and the ``green''
nebulæ whose spectra are distinctly gaseous. The Andromeda Nebula is
the great representative of the former class and the Orion Nebula of
the latter. The spectrum of the Andromeda Nebula has been interpreted
to mean that it consists not of luminous gas, but of a flock of stars
so distant that they are separately indistinguishable even with
powerful telescopes, just as the component stars of the Milky Way are
indistinguishable with the naked eye; and upon this has been based the
suggestion that what we see in Andromeda is an outer universe whose
stars form a series of elliptical garlands surrounding a central mass
of amazing richness. But this idea is unacceptable if for no other