lements identical with
those which are found in the solar system. Such facts as these make it
probable that the career of other stars, when adequately inquired
into, would be found to be like that of our own sun. Observation daily
enhances this probability, for our study of the sidereal universe is
continually showing us stars in all stages of development. We find
irregular nebulae, for example; we find spiral and spheroidal nebulae;
we find stars which have got beyond the nebulous stage, but are still at
a whiter heat than our sun; and we also find many stars which yield the
same sort of spectrum as our sun. The inference seems forced upon us
that the same process of concentration which has gone on in the case
of our solar nebula has been going on in the case of other nebulae. The
history of the sun is but a type of the history of stars in general. And
when we consider that all other visible stars and nebulae are cooling
and contracting bodies, like our sun, to what other conclusion could we
very well come? When we look at Sirius, for instance, we do not see
him surrounded by planets, for at such a distance no planet could be
visible, even Sirius himself, though fourteen times larger than our sun,
appearing only as a "twinkling little star." But a comparative survey
of the heavens assures us that Sirius can hardly have arrived at his
present stage of concentration without detaching, planet-forming rings,
for there is no reason for supposing that mechanical laws out there are
at all different from what they are in our own system. And the same kind
of inference must apply to all the matured stars which we see in the
heavens.

When we duly take all these things into the account, the case of our
solar system will appear as only one of a thousand cases of evolution
and dissolution with which the heavens furnish us. Other stars, like our
sun, have undoubtedly started as vaporous masses, and have thrown off
planets in contracting. The inference may seem a bold one, but it after
all involves no other assumption than that of the continuity of natural
phenomena. It is not likely, therefore, that the solar system will
forever be left to itself. Stars which strongly gravitate toward each
other, while moving through a perennially resisting medium, must in
time be drawn together. The collision of our extinct sun with one of the
Pleiades, after this manner, would very likely suffice to generate even
a grander nebula than the one with