und could be
produced, no matter how many thousands of tons of rock might fall to the
ground.

"Tremendous changes of this nature may be happening on the moon, but our
telescopes are not powerful enough to enable us to see the results. They
would have to cover an area of miles to be noticeable, unless they
presented some particularly striking configuration."

"Professor," exclaimed M'Allister, "how is it that all the shadows on
the moon are such a dense black and so sharply defined at the edges?"

"That," I exclaimed, "is entirely owing to the absence of the
atmosphere. On the earth, even at night time, some light is diffused by
our atmosphere, and shadows are never dense black even when thrown by a
bright sun. On the moon it is black darkness everywhere outside the
direct rays of the sun, and there is no gradual diminution of the
darkness about the edges of shadows such as we see on the earth. The
only mitigation of the blackness is seen where some light is reflected
across from the rocky walls on which the sun is shining.

"In those deep recesses down at the bases of the mountains the cold must
be most intense and the darkness truly awful. It all looks very nice
when the sun is shining, but appearances are often deceptive, and do not
improve on a closer acquaintance."

We could not have landed upon the moon if we had desired to do so, for
no provision had been made for a supply of air by means of helmets and
other apparatus. I kept my own counsel in this matter, as I had very
good reasons for discountenancing any proposal to investigate the lunar
scenery too closely.

By a curious coincidence, not long after this conversation we had ocular
demonstration of the fact that the moon is liable to changes from other
agencies than those of expansion and contraction.

We were looking at some distant mountains which were in the full
sunshine. Suddenly a dark shadowy looking mass shot across the sky and
struck one of the mountain peaks some distance down from the top. The
peak seemed to be immediately demolished, and vanished from our sight!

M'Allister gazed spellbound; but John excitedly exclaimed: "Did you see
that, Professor? One moment the peak was there, and the next moment it
was gone!"

"Yes," I said. "Undoubtedly that dark shadow was a large meteoric stone.
Many have fallen on our earth at various times, some being tons in
weight. Usually, however, they are so small that on entering our
atmosphere they becom