le valleys. Hills and valleys alike were densely
clothed with forest.

Hart pointed to several, large holes in the sides of the hills, always
at or near the base and said they were the mouths of caves.

"But the big one, in which I got the peter dirt is farther on," he said.

They came to the place he had in mind, just as the twilight was falling,
a hole, a full man's height at the bottom of a narrow valley, but
leading directly into the side of the circling hill that inclosed the
bowl-like depression. Henry and Paul looked curiously at the black mouth
and they felt some tremors at the knowledge that they were to go in
there, and to remain inside the earth for a long time, shut from the
light of day. It was the dark and not the fear of anything visible, that
frightened them.

But they made no attempt to enter that evening, although night would be
the same as day in the cave. Instead they provided for a camp, as the
horses and a sufficient guard would have to remain outside. The valley
itself was an admirable place, since it contained pasturage for the
horses, while at the far end was a little stream of water, flowing out
of the hill and trickling away through a cleft into another and slightly
lower valley.

After tethering the horses, they built a fire near the cave mouth and
sat down to cook, eat, rest and talk.

"Ain't there danger from bad air in there?" asked Ross. "I've heard tell
that sometimes in the ground air will blow all up, when fire is touched
to it, just like a bar'l o' gunpowder."

"The air felt just as fresh an' nice as daylight when I went in," said
Hart, "an' if it comes to that it will be better than it is out here
because it's allus even an' cool."

"It is so," said the master meditatively. "All the caves discovered so
far in Kentucky have fresh pure air. I do not undertake to account for
it."

That night they cut long torches of resinous wood, and early the next
morning all except two, who were left to guard the horses, entered the
cave, led by Hart, who was a fearless man with an inquiring mind.
Everyone carried a torch, burning with little smoke, and after they had
passed the cave mouth, which was slightly damp, they came to a perfectly
dry passage, all the time breathing a delightfully cool and fresh air,
full of vigor and stimulus.

Paul and Henry looked back. They had come so far now that the light of
day from the cave mouth could not reach them, and behind them was only
thick impe