times that of the smaller. They are known as the Magellanic Clouds,
having been called after the navigator Magellan. Both are visible on a
moonless night, but in bright moonlight the smaller disappears. Sir John
Herschel, when at the Cape of Good Hope, examined those objects with his
powerful telescope. He described them 'as consisting of swarms of stars,
globular clusters, and nebulae of various kinds, some portions of them
being quite irresolvable, and presenting the same milky appearance in
the telescope that the nebulae themselves do to the naked eye.' These are
believed to be other universes of stars sunk in the profound depths of
space, our knowledge of their existence being dependent upon the faint
nebulous light which left them, perhaps, several thousand years ago.

[Illustration: GREAT NEBULA IN ORION]

The description of the various kinds of nebulae leads us to consider what
is called the Nebular Hypothesis. That the stars and solar system had at
some time in the past a beginning, is as much a matter of certainty as
that they will at some future time cease to be. Stars, like organic
beings, have their birth, grow and arrive at maturity, then decline into
a state of decrepitude, and finally die out. The duration of the life of
a star, which may be reckoned by millions of years, depends upon the
length of time during which it can maintain a temperature that renders
it capable of emitting light. By the constant radiation of its heat into
space, a condition of its constituent particles consequent upon the
gradual contraction of its mass will ultimately occur, which will result
in the exhaustion of its stores of thermal energy, the extinction of its
light, and the reduction of what was once a brilliant orb to the
condition of a mass of cold, opaque, inert matter. Inquiries as to the
origin of the stars have led scientific men to conclude that they have
been evolved from gaseous nebulae, and these have therefore been regarded
as indicating the earliest stage in the formation of suns and planets.
It is believed that the condensation of those attenuated masses of
luminous matter into stars is capable of accounting for the generation
and formation of all the shining orbs which enter into the structure of
the starry heavens. In the evolution of a 'cosmos out of a chaos' we
should expect to find stars presenting every stage of development--some
in an embryo state and others more advanced; stars in full vigour and
activ