lanterns ready for use,
and descended the stairs for a distance of fifteen feet.

They found themselves in a big natural cavern, and as they flashed
their lantern lights around in the gloom, a cry of the most intense
astonishment burst from their lips.

CHAPTER XV.

THE PRISONER IN THE CAVE.

"Harry, this is the most astonishing place I ever was in in all my
life."

"It certainly is wonderful, Old King Brady."

The detectives were gazing in amazement where the lights of their
lanterns rested, and beheld a wonder of nature very seldom seen.

In the first place, they were in a huge cavern of circular shape.

The flight of stairs wound around one of the walls, and beside the
bottom step there was a yawning hole in the ground fifty feet in
diameter.

It seemed to go straight down into the earth.

Harry picked up a big stone and dropped it into the opening.

They listened intently, but failed to hear it strike bottom in the pit.

"This hole must be of enormous depth!" the boy exclaimed, "else we
would have heard that stone hit the bottom."

"Look at the church organ rising up from the depths against that side
of the abyss," said Old King Brady, pointing across the chasm.

His light rested upon a number of stalactites forming what looked
exactly like the pipes of an enormous organ.

Beneath them was a bank of keys.

The silence of death prevailed.

Nature had wrought a wonderful formation there.

The entire interior of the cave was pure white, looking like camphor.

Huge pendants like great icicles hung from the ceiling, and similar
formations rose from the floor.

In some cases the ends of the pendants nearly touched the points of the
stalagmites rising from the bottom, and not a few were dropping pure,
clear water, which formed little pools that ran in rivulets to the
great well, and there vanished in the bowels of the earth.

It was quite cold there, yet there was a strong, fresh, invigorating
taste to the air, which was agreeable to the lungs.

At various parts of the walls were other natural formations, and among
them, in a niche, the figure of a woman holding a child.

"For beauty, the Mammoth Caves of Kentucky cannot compare with this
place," said Young King Brady, in tones of delight.

"We are forgetting our object," said the old officer.

"True. But no one is in this place."

"Let us see if there are not adjoining caverns."

"Explore those openings in the wall."

He pointed