ering torch, and
uttered a loud _cooey_.

Nic caught at his arm, for there was a crash, and a bellowing roar as
the cry went echoing away and then gradually died out in whispers.

"Startling, isn't it? But only sound. The cavern is enormous here."

"It's dreadful!" panted Nic.

"No: wonderful and grand, boy. Ah! who knows what may be deeper down in
the interior of this mighty world on which we crawl! Come along; you'll
have other chances of exploring here--that is, if you come to see me,
Nic. Would you venture alone?"

"No," said Nic frankly. "I don't think I should dare."

"Familiarity breeds contempt--even for darkness, Nic," said the convict
with a laugh, which sounded horrible. "Don't be in a hurry to say that.
I believe that with a lantern you would come. Forward, boy!"

"Is it much farther?"

"Oh yes--a long, long, long way. I was months before I got right
through."

"What!" cried Nic in a startled voice; and he wished he had not spoken,
for his exclamation sounded as if it would bring down the rocks upon
their heads.

"No, no; not as you take it," said the convict laughingly, as he waved
the torch and made it glow. "I mean that after I discovered it one day,
as I told you, through a sheep falling down into that well-like opening,
I made myself a rough lamp from an old pannikin, some melted mutton fat,
and a bit of rag, and when I had chances I came down and followed the
stream a little farther and a little farther, led on and on by the
interest of the place, always expecting to find that it would end with
an underground lake."

"And it did not?"

"No, this little stream joins the river in the great valley, as you will
see. But we are losing time. Come on."

Nic followed in silence, but with the creepy, shivering sensation
passing off; and a feeling of intense curiosity and wonder taking its
place.

"Is it much farther?" he said at last.

"Like to go back now, boy?"

"No," cried Nic firmly--"of course not."

"Well, as to being farther to go, I could turn off in several places,
and we could wander on for longer than I could say. You can bring
friends and explore it some day, perhaps; but down to the valley is not
a great way now."

"Down! Are we going down?"

"Of course: flowing water is always going downward. There, you can hear
that the rocks are farther away to right and left. Farther on they
close in again till it is like a crack, and they run up to a point far
above o