here," he cried, jerking the nearly burned-out match out into
the gloom.

"Try another," said Chris sharply.

This was done, and a fresh examination made, but as far as could be seen
the great square pit cut out of the rock went down smooth and square
without a sign of foothold.

"I wonder how deep it is," said Chris, in a whisper tinged with awe.

"We'll soon find that out," said the American. "Is there a loose stone
anywhere about?"

"Yes, plenty on the terrace outside," said Ned, and he stepped back,
passed out of the window-opening, and returned with a piece of shale as
big as his hand.

"Pitch it right out in the middle, squire," cried Griggs, and the
fragment quitted the boy's hand, to fall with a sharp sound upon stone,
as near as they could guess some thirty feet below.

"You're wrong, Griggs," said the doctor.

"Am I, sir? Well, not the first time by many."

"If this place had been as you think, the bottom would be covered with
ashes like those we saw glide down, and that stone would have fallen
with a dull thud."

"Very likely, sir. That's only how it seemed to me. Shall I go down
now and see?"

"No; let's climb up to the next range and see what that tells us; we may
find some explanation there. Mind how you go, Chris; these steps are
risky."

"Yes, I'll take care, father," panted the boy, who was already climbing.
"I don't want to tumble down there."

The height climbed was greater than that of the two lower ascents, but
proved to be fairly easy to one whose nerves were steady, and as he
reached the top Chris called down--

"It's so gloomy because the cliff overhangs it so. My word! There's
been some fighting here!"

The rest followed him quickly, and as they gathered, all noticed that
there was a fairly wide ledge on all four sides of the place, forming a
pathway fairly level, and chipped out of the solid cliff; while, making
quite a breastwork at the edge, but irregular in the extreme, stones of
all shapes and sizes were piled-up, quite regularly along the side
farthest from the rough steps, and of all heights in other parts, the
stones nearest to the steps being only few.

Griggs came last, and he noted this appearance, and uttered a deep grunt
as he pointed out the rough breastwork, but said nothing.

"Stones used for building and squaring the openings on to the terrace, I
suppose," said Bourne, and the boys looked at them curiously.

"What about mortar?" said Ned.

"Thin