the doctor.

"What, about the rattlers, father?"

"Of course; but I meant where you place your feet. Many of the stones
are rotten and loose."

"We'll mind," said Chris, and he began to climb, raising himself a step
or two, and then striking sharply in amongst some growing plants, before
thrusting his staff up in front of him and drawing himself up again.

This he kept on repeating, and without much difficulty climbed some
thirty feet, before an awkward place came like a check, caused by a big
stone having fallen, leaving a good-sized cavity.

"Look out now, Ned," he said softly. "Here's a hole that may hold one."

"All right," was the reply, and as Chris planted his feet firmly, one in
a hole and the other on a projecting stone, Wilton uttered a warning
word or two, which the boys were too busy to heed.

"It's a bigger place than I thought," said Chris, taking fast hold of a
stone with his left hand and advancing his tufted staff with his right,
as he stood well upright, bringing his head above the edge of the hole.
"It was built-up once, for the stones were square, and it goes in quite
deep. Now, then, look out for a big one."

He leaned a little on one side, thrust in the stick, and gave it a sharp
rattle round in different directions, when to his horror there was a
rush which nearly made him loosen his hold before he realised what had
happened. But fortunately he held on, and in an instant the alarm and
danger had passed away. For the occupants he had disturbed proved to be
some half-dozen huge bats, which fluttered out, squealing, and made for
the opposite side of the depression.

"Phew! How they smell! Cockroachy," cried Chris. "I say, father,
there are not likely to be snakes here now."

"No," said the doctor. "If there were I should not think that you would
have found the bats. But be careful."

Chris said nothing, but climbed right into the hole.

"Here, come on, Ned," he cried; "this isn't a hole made by some stone
falling over; it's quite a little chamber, with--What's that?" he
added--"A chimney?"

A minute's investigation proved that it was no chimney that had taken
his attention, but a sloping shaft with plenty of room for a man to pass
upward, and the way made easy by projecting stones.

"You are not going in there?" said Ned anxiously, as he stood close
behind.

"But I am. Come and look. You can see daylight. Why, Ned, it's the
way up to the first terrace. Come on."

Chr