k, I've heard the stories you speak of,
which have been told chiefly by persons who had lost their way and were
nearly dead from cold and hunger. Under such circumstances, when
people's nerves and senses begin to fail them, they fancy all sorts of
strange things. No doubt, too, there are all sorts of acoustic
deceptions in these wild regions, as there are optical delusions; but I
don't think we four--all of us in sound health--are likely to be so
deceived--"

"But how about the savages, doctor?" interposed Nick, anxiously.

"Well, if these were the backwoods of America, and we had the Red
Indians to deal with, there would be a good deal in your suggestion.
But neither the Hottentots nor the Bushmen are given to stratagems of
this kind. However, we'll move warily, and if any treachery is
designed, we shall be pretty sure to baffle it."

They turned off in the direction whence the cry had come, keeping to the
open ground, and giving a wide berth to any clump of trees or underwood
which might harbour an enemy. Every now and then they paused to listen
for the sound, which was regularly repeated, at intervals apparently of
two or three minutes, and grew more distinct as they advanced. It was
now certain that the cry was human, and sounded like that of a
full-grown man.

"We are getting a good deal nearer," observed Warley, as they passed the
last patch of trees, and entered once more the sandy wilderness. "I
should say we must be almost close, only I don't see any place where the
person who is crying out in this manner can be hidden."

"It comes from that heap of stones there," exclaimed Frank, "that heap
to the left, I mean--about two hundred yards further on."

"I see the stones, Frank, plain enough," said Mr Lavie, "but a man
couldn't be hidden among them. You call it a heap of stones, but there
is no heap. There is not so much as one lying upon another."

"Nevertheless the cry comes from there," said Warley; "I heard it the
last time quite plainly. Let us go up and see."

They cautiously approached the spot in question, where there were about
thirty or forty moderate-sized stones scattered on the plain. As they
advanced the mysterious call was again heard.

"I see who it is that's making it," shouted Wilmore. "It's a fellow
whose head is just above ground. I took his head for a black stone,
with a lot of moss growing on it. But now I can see that it is a head,
though the features are turned away fr