north so long as they were not on the warpath, but I
shouldn't like to trust any of these."

"Then you'd prepare for the worst?"

"That's the only way to deal with these people, sir," said the American
sternly. "If they see that we're weak they'll take our mules and
ponies, and perhaps our lives--at once. If they take our animals and
leave us alone they've taken our lives all the same, for we could never
reach civilisation again without our beasts."

"No," said the doctor firmly. "I should have liked to retreat if we
could."

"We couldn't do it," said Wilton sharply, as he took his eyes from the
glass. "There would not be time, and if we could get away they'd follow
our trail and take us at a disadvantage, for certain."

"Yes," said the doctor; "there is no other chance. As you suggest,
Griggs, if they find us strong they will fear us. We must decide at
once which of the cells we will hold, and get our stores there as
quickly as possible."

"That is already settled, sir," said the American coolly. "We must hold
the place where we can reach the water, and the lowest floor here is the
one."

"You are confident, then, that they couldn't get at us from above?"

"Quite, sir. The attack, if it comes, will be from below, as it was
made once before."

Chris and Ned exchanged glances as they recalled all that they had seen
and the result to the defenders, and a blank look of despair settled in
their countenances.

As it happened the doctor was watching them keenly at the time, his
breast full of anxiety for the lads about to be brought face to face
with such grave peril, and he spoke out cheerfully as if in answer to
the thoughts he had just read in their faces.

"Yes," he said, "but you forget. Those people had to defend themselves
with stones. We have the best of modern firearms, and can deal out
death and destruction to our enemies from a distance while we are
sheltered and quite beyond their reach. Well, Wilton, what do you make
out?"

"They are all gathered closely together, pretty well a hundred strong,"
was the reply, "and one man--the chief, I suppose--is haranguing the
rest. He keeps on gesticulating and pointing down at the mules, and
then waving his hands in different directions as if to show which way
they ought to go."

"Well," said the doctor, "we must not stir until they move off. They
evidently have not seen us, and they may after all believe the animals
to be wild."

"Yes, sir; a