he volcanic dust was carried by a strong wind,
split up into two or more separate currents by a succession of peaks.
The wind currents swept clean the area over which they actually passed,
but dust fell or drifted in the lines between the currents. Exactly the
same thing may be observed in connection with snow-storms on our earth
when accompanied by a high wind. One part of the earth's surface will be
swept clean by the wind current, whilst a long line of the adjoining
surface is covered with a thick deposit of snow. I have also noticed
that where the ray-streaks impinge upon a mountain, or ring, there is an
appearance of spreading out and heaping up of the bright material very
much as snow would be spread out or drifted up in similar situations on
the earth."

M'Allister here interrupted with the remark that, when we were
approaching the moon, he had particularly noticed that all appearance of
the face of the "man in the moon" had vanished. He said he had expected
to see that more distinctly as we got nearer.

"That would not be the case, M'Allister," I answered. "The resemblance
to a human face which we see from the earth is caused by the combined
effect of the bright and dusky areas on the lunar surface as seen from a
distance. The depressed dark areas, which we call seas, form the eyes,
nose, and mouth of the face, but when we had approached nearer to the
moon the details of the surface configuration stood out so much more
distinctly that they entirely obliterated the general effect of the
markings as seen from a distance."

"Professor," exclaimed John, "I have read that before telescopes were
invented it was thought by many that the markings seen on the moon were
really the features of our own earth reflected by the moon as in a
mirror. Is that correct?"

"Oh yes, John," I said. "It seems to have been a fairly general belief
in many parts of the world, and travellers tell us that, even within
very recent times, they have found in some of the more out-of-the-way
parts of the world that the same idea is still held by uneducated
people!"

Objects of interest being so numerous on the lunar surface we could only
give a comprehensive glance at many of them, and as we had so many
places to inspect, I now gave M'Allister the order to steer eastward.

He accordingly moved his switches and the _Areonal_ quickly passed over
the Sea of Tranquillity, which has an area of 140,000 square miles; then
over the Sea of Vapours