lecules of
oxygen, nitrogen, and other gases. It therefore follows that none of
these gases could remain permanently to form an atmosphere at the
surface of so small a body as the moon. This seems to be the reason why
there are no present traces of any distinct gaseous surroundings to our
satellite.

The absence of air and of water from the moon explains the sublime
ruggedness of the lunar scenery. We know that on the earth the action of
wind and of rain, of frost and of snow, is constantly tending to wear
down our mountains and reduce their asperities. No such agents are at
work on the moon. Volcanoes sculptured the surface into its present
condition, and, though they have ceased to operate for ages, the traces
of their handiwork seem nearly as fresh to-day as they were when the
mighty fires were extinguished.

"The cloud-capped towers, the gorgeous palaces, the solemn temples" have
but a brief career on earth. It is chiefly the incessant action of water
and of air that makes them vanish like the "baseless fabric of a
vision." On the moon these causes of disintegration and of decay are all
absent, though perhaps the changes of temperature in the transition from
lunar day to lunar night would be attended with expansions and
contractions that might compensate in some slight degree for the absence
of more potent agents of dissolution.

It seems probable that a building on the moon would remain for century
after century just as it was left by the builders. There need be no
glass in the windows, for there is no wind and no rain to keep out.
There need not be fireplaces in the rooms, for fuel cannot burn without
air. Dwellers in a lunar city would find that no dust could rise, no
odours be perceived, no sounds be heard.

Man is a creature adapted for life under circumstances which are very
narrowly limited. A few degrees of temperature more or less, a slight
variation in the composition of air, the precise suitability of food,
make all the difference between health and sickness, between life and
death. Looking beyond the moon, into the length and breadth of the
universe, we find countless celestial globes with every conceivable
variety of temperature and of constitution. Amid this vast number of
worlds with which space is tenanted, are there any inhabited by living
beings? To this great question science can make no response: we cannot
tell. Yet it is impossible to resist a conjecture. We find our earth
teeming with life