he scraped the tool backwards
and forwards over what seemed to be a perfectly level surface.

"You are quite right, Denham," said the doctor excitedly, "and you have
proved my words. Now then, Dance; jump down with that shovel and help
Denham clear out the loose stuff."

This took some little time, but at last the two men stood up in the
square hole, which was thoroughly cleared out, and exposed the level
flooring of the old building beneath one of whose walls they had been at
work.

"What?" cried the doctor, in answer to a question. "How far does it go?
It is impossible to say without clearing out the whole extent of the
place. What is the bottom, Denham--slabs of stone or bricks?"

"Neither, sir. As far as I can make out it's a kind of cement."

"Then that proves that the building can't be as old as we thought," said
Sir James.

"Oh, no," said the doctor. "Cement in some form or another is very
ancient;" and he paused for a few minutes while the last baskets of
rubbish which had been thrown out were carefully examined.

"Nothing here," said the doctor. "Now, Denham, I want that iron bar
that you use to make the holes for the tent pegs."

"Hop pitcher? Here, Bob, mate, run to the waggon and fetch it."

The interval of time taken by the younger keeper to fetch the big
pointed crowbar was utilised for further search, during which the two
blacks came back and stood a little aloof, watching curiously the acts
of their white companions.

"That's right, mate," replied Denham.--"Oh, well, if you like; jump
down, then. The boss wants a hole picked, I suppose, for you to break
up a bit of the floor here to see what it's like."

The keeper was handy enough with the fresh tool, and after picking out a
good many small pieces of what proved to be powdered granite,
consolidated probably by lime, or perhaps only by time itself, he called
for one of the stones that had been thrown out, laid it by the side of
the hole he had picked, and then thrusting down the iron bar and using
the stone as a fulcrum, he levered out a good-sized piece of the hard
cement.

"Throw it up here," cried the doctor, who caught it deftly and held it
in the sunshine, examining it carefully. "No," he said, in rather a
disappointed tone.

"Here's a bigger bit here, sir," said Bob, "as seems loose. Yes, out
you come!" And pressing his lever down hard, he brought up a great
flake of the flooring, nearly a foot long and some inches wide.