from the floor. In this he perceived lines of crevice marking out a
rectangular space some six inches wide and four feet in height.

"Ha, ha!" cried Burke. "The handle is on the other side of that slab,
I'll bet my head!" And putting down the lantern, he went to work.

With his hammer and chisel he had forced the top of the slab in less than
two minutes, and soon he pulled it outward and let it drop on the floor.
Inside the narrow, perpendicular cavity which was now before him, he saw
an upright metal bar.

"The handle of the bolt!" cried Burke. "Now I can unfasten the
trap-door." And taking hold of the top of the bar, he pulled back with
all his force. At first he could not move it, but suddenly the resistance
ceased, and he pulled the bar forward until it stood at an angle of
forty-five degrees from the wall. Further than this Burke could not move
it, although he tugged and bore down on it with all his weight.

"All right," said he, at last. "I guess that's as far as she'll come.
Anyway, I'm off to see if I've drawn that bolt. If I have, I'll have that
trap-door open, if I have to break my back lifting it."

With his best speed Burke ran through the caves to the mound, and,
mounting by means of the stone projections, he was about to descend by
the ladder, when, to his utter amazement, he saw no ladder. He had left
it projecting at least two feet through the opening in the top of the
mound, and now he could see nothing of it.

What could this mean? Going up a little higher, he held up his lantern
and looked within, but saw no signs of the ladder.

"By George!" he cried, "has anybody followed me and pulled out
that ladder?"

Lowering the lantern farther into the mound, he peered in. Below, and
immediately under him, was a black hole, about three feet square.
Burke was so startled that he almost dropped the lantern. But he was a
man of tough nerve, and maintained his clutch upon it. But he drew
back. It required some seconds to catch his breath. Presently he
looked down again.

"I see," said he. "That trap-door was made to fall down, and not to lift
up, and when I pulled the bolt, down it went, and the ladder, being on
top of it, slipped into that hole. Heavens!" he said, as a cold sweat
burst out over him at the thought, "suppose I had made up my mind to cut
that bolt! Where would I have gone to?"

It was not easy to frighten Burke, but now he trembled, and his back was
chilled. But he soon recovered sufficie