ano has burst up and vomited out floods of lava and
debris, this has fallen down in a ring a little distance away from it,
leaving a clear space next to the peak, so that, as the mountain ceases
vomiting and the lava cools down, the ring hardens and forms a circular
ridge. The craters on the moon are immense, not only in proportion to
her size, but immense even according to our ideas on the earth. One of
the largest craters in our own world is in Japan, and this measures
seven miles across, while in the moon craters of fifty, sixty, and even
a hundred miles are by no means uncommon, though there are also hundreds
and thousands of smaller ones. We can see the surface of the moon very
plainly with the magnificent telescopes that have now been made, and
with the best of these anything the size of a large town would be
plainly visible. Needless to say, no town ever has been or ever will be
seen upon the moon!

All these mountains and craters show that at one time the moon must have
been convulsed with terrific disturbances, far worse than anything that
we have any knowledge of on our earth; but this must have been ages
ago, while the moon still probably had an atmosphere of its own. Now it
has long been quiet. Nothing changes there; even the forces that are
always at work on the earth--namely, damp and mould and water--altering
the surface and breaking up the rocks, do not act there, where there is
no moisture of any sort. So far as we can see, the purpose of the moon
is to be the servant of the earth, to give her light by night and to
raise the tides. Beautiful light it is, soft and mysterious--light that
children do not often have a chance of seeing, for they are generally in
bed before the moon rises when she is at the full.

We know that the moon has no heat of her own--she parted with all that
long ago; she cannot give us glowing light from brilliant flames, as the
sun does; she shines only by the reflection of the sun on her surface,
and this is the reason why she appears to change her shape so
constantly. She does not really change; the whole round moon is always
there, only part of it is in shadow. Sometimes you can see the dark part
as well as the bright. When there is a crescent moon it looks as if it
were encircling the rest; some people call it, 'seeing the old moon in
the new moon's arms.' I don't know if you would guess why it is we can
see the dark part then, or how it is lighted up. It is by reason of our
o