have been forward from time to time prognosticating
the end of the earth, and consequently of human life. We will conclude
with a recital of a few of them, though which, if any, is the true one,
the Last Men alone can know.

Just as a living creature may at any moment die in the fulness of
strength through sudden malady or accident, or, on the other hand, may
meet with death as a mere consequence of old age, so may our globe be
destroyed by some sudden cataclysm, or end in slow processes of decay.
Barring accidents, therefore, it would seem probable that the growing
cold of the earth, or the gradual extinction of the sun, should after
many millions of years close the chapter of life, as we know it. On the
former of these suppositions, the decrease of temperature on our globe
might perhaps be accelerated by the thinning of the atmosphere, through
the slow escape into space of its constituent gases, or their gradual
chemical combination with the materials of the earth. The subterranean
heat entirely radiated away, there would no longer remain any of those
volcanic elevating forces which so far have counteracted the slow
wearing down of the land surface of our planet, and thus what water
remained would in time wash over all. If this preceded the growing cold
of the sun, certain strange evolutions of marine forms of life would be
the last to endure, but these, too, would have to go in the end.

Should, however, the actual process be the reverse of this, and the sun
cool down the quicker, then man would, as a consequence of his
scientific knowledge, tend in all probability to outlive the other forms
of terrestrial life. In such a vista we can picture the regions of the
earth towards the north and south becoming gradually more and more
uninhabitable through cold, and human beings withdrawing before the
slow march of the icy boundary, until the only regions capable of
habitation would lie within the tropics. In such a struggle between man
and destiny science would be pressed to the uttermost, in the devising
of means to counteract the slow diminution of the solar heat and the
gradual disappearance of air and water. By that time the axial rotation
of our globe might possibly have been slowed down to such an extent that
one side alone of its surface would be turned ever towards the fast
dying sun. And the mind's eye can picture the last survivors of the
human race, huddled together for warmth in a glass-house somewhere on
the e