thirst.

They then returned to where they had dined; and, being now much wearied
with their long-continued exertions, they stretched themselves upon the
rocks with the intention of having some sleep. Though their bed was a
hard one, it was not cold; for in the interior of great caverns it is
never cold. There the temperature is more equable than that of the
atmosphere without--being cooler in summer and warmer in winter, so that
variety is scarcely known--at all events, the extremes of heat and cold
are never felt. This is the ease with the Mammoth Cave of Kentucky, and
other large caverns; and on this account it has been thought that
persons suffering from pulmonary complaints might derive benefit by
dwelling in caves. There are many such patients who make their home in
the Mammoth; and where a commodious hotel enables them to live in
comfort, and even luxury! It is possible enough that the mild and
equable temperature that exists under ground may enable the victim of
consumption to prolong life for a considerable time: but it is doubtful
whether any radical cure can be effected in this way; and the
unfortunate sufferer, once he emerges from his subterranean dwelling,
will be in as much danger from the insidious disease as before.

Little did Karl, Caspar, and Ossaroo, care for the mild atmosphere that
surrounded them in the cavern. They would gladly have exchanged it for
the hottest country in the torrid zone, or the coldest spot in all the
Arctic regions. Biting mosquitos in the former, or biting frost in the
latter, would have been more welcome than that mild and gentle climate
that surrounded them--that gloomy atmosphere, where sun had never shone,
and where snow had never fallen.

Notwithstanding their anxiety of mind, their weariness at length
overcame them, and all three fell fast asleep.

CHAPTER FIFTY NINE.

EXPLORATION OF THE CAVE.

They slept a good long while, though, whether if was by night or by day,
they had no means of judging. They could only guess at it, by
remembering how much time had transpired since they first entered the
cave; but to show how little trust can be placed in any conjectures of
this sort, they differed from one another in their estimates full twelve
hours!

Karl thought they had been wandering about nearly two days and a night;
while the others believed the time not so long by twelve hours at least.

Karl adduced a reason for his belief--the ravenous appetite wh