studied this through the telescope, as it is a most interesting
formation.

"Well, Professor," remarked M'Allister, "I have travelled nearly all
over our own world, but in all my journeyings I have never seen such
wild and rugged scenery as I have during the few hours we have been
passing over the moon. The mountains seem to be split and rent in all
directions, especially where there are volcanic craters in the
neighbourhood--and, really, they seem to be everywhere; while landslips
are very numerous, and the mountain passes are extremely rugged and
gloomy."

"Yes," I replied, "my telescopic observations had prepared me for a
great deal, but the weird ruggedness of the lunar scenery exceeds all
my anticipations."

"What is the explanation of it all?" M'Allister inquired.

"I should think, M'Allister, that much of it was originally caused by
the extreme violence of volcanic outbursts," I answered; "but the
excessive expansion and contraction, resulting from the alternate spells
of intense heat and intense cold to which the moon is continually
exposed, will account for the formation of many of those tremendous
chasms and precipices which we see everywhere around us, as well as for
the huge mounds of dislodged rocks and _debris_, which are piled up in
such chaotic confusion on the ledges of the mountains and round their
bases.

"On the earth such _debris_ would very soon have become smoothed by
atmospheric erosion, the interstices would have been filled up with dust
and soil, while the growth of vegetation would have added a new charm to
the effect.

"You have seen the great landslip in the Isle of Wight! When it fell all
was wild desolation, but it has become covered with such a luxuriant
growth of vegetation that it now presents a scene of beauty.

"On the moon, however, there is neither atmosphere, rain, nor moisture
to produce weathering of the rocks or to encourage the growth of
vegetation; so the rocks remain just as sharp, rugged, and bare as they
were ages ago when they were first split off from the mountains.

"No doubt very large masses of rocks are still frequently being
dislodged, and if we could see them falling from the upper part of a
mountain, rebounding along the spurs, with fragments flying in all
directions and ultimately dashing to pieces at the base, it would seem
to us most uncanny not to hear the slightest sound arising from all this
apparent commotion. Without an atmosphere, however, no so