on three hundred and eighty-four thousand four hundred and
seventy-two times larger than the earth. Of the substance of the sun it
is not so easy to speak. Still it is thought, though it is not certain,
that we occasionally see the actual surface of this orb, an advantage
we do not possess as respects any other of the heavenly bodies, with
the exception of the moon and Mars. The light and warmth of the sun
probably exist in its atmosphere, and the spots which are so often seen
on this bright orb, are supposed to be glimpses of the solid mass of
the sun itself, that are occasionally obtained through openings in this
atmosphere. At all events, this is the more consistent way of
accounting for the appearance of these spots. You will get a better
idea of the magnitude of the sidereal system, however, by remembering
that, in comparison with it, the distances of our entire solar system
are as mere specks. Thus, while our own change of positions is known to
embrace an orbit of about 200,000,000 of miles, it is nevertheless so
trifling as to produce no apparent change of position in thousands of
the fixed stars that are believed to be the suns of other systems. Some
conjecture even that all these suns, with their several systems, our
own included, revolve around a common centre that is invisible to us,
but which is the actual throne of God; the comets that we note and
measure being heavenly messengers, as it might be, constantly passing
from one of these families of worlds to another."

I remember that one of the astronomer's pupils asked certain
explanations here, touching the planets that it was thought, or rather
known, that we could actually see, and those of which the true surfaces
were believed to be concealed from us. "I have told you," answered the
man of science, "that they are the Moon, Mars and the Sun. Both Venus
and Mercury are nearer to us than Mars, but their relative proximities
to the sun have some such effect on their surfaces, as placing an
object near a strong light is known to have on its appearance. We are
dazzled, to speak popularly, and cannot distinguish minutely. With Mars
it is different. If this planet has any atmosphere at all, it is one of
no great density, and its orbit being without our own, we can easily
trace on its surface the outlines of seas and continents. It is even
supposed that the tinge of the latter is that of reddish sand-stone,
like much of that known in our own world, but more decide