d according
to his habit, he stroked his stomach.

Stas did not like this method of hunting; so he began to ask what other
game there was in the Wahima country and they conversed further about
antelopes, ostriches, giraffes, and rhinoceroses until the roar of a
waterfall reached them.

"What is that?" Stas exclaimed. "Are there a river and waterfall ahead
of us?"

Kali nodded his head in sign that obviously such was the fact.

And for some time they rode more quickly, listening to the roar which
each moment became more and more distinct.

"A waterfall!" repeated Stas, whose curiosity was aroused.

But they had barely passed one or two bends when their way was barred
by an impassable obstruction.

Nell, whom the motion of the horse had lulled to sleep, awoke at once.

"Are we already stopping for the night?" she asked.

"No, but look! A rock closes the ravine."

"Then what shall we do?"

"It is impossible to slip beside it for it is too close there; so it
will be necessary that we turn back a little, get on top, and ride
around the obstruction; but it is yet two hours to night; therefore we
have plenty of time. Let us rest the horses a little. Do you hear the
waterfall?"

"I do."

"We will stop near it for the night."

After which he turned to Kali, ordered him to climb to the brink of the
ridge and see whether, beyond, the ravine was not filled with similar
obstructions; he himself began to examine the rock carefully, and after
a while he exclaimed:

"It broke off and tumbled down not long ago. Nell, do you see that
fragment? Look how fresh it is. There is no moss on it, nor vegetation.
I already understand, I understand!"

And with his hand he pointed at a baobab tree growing on the brink of
the ravine whose huge roots hung over the wall and were parallel with
the fragment.

"That root grew in a crevice between the wall and the rock, and growing
stronger, it finally split the rock. That is a singular matter for
stone is harder than wood; I know, however, that in mountains this
often happens. After that anything can shake such a stone which barely
keeps its place, and the stone falls off."

"But what could shake it?"

"It is hard to say. Maybe some former storm, perhaps yesterday's."

At this moment Saba, who previously had remained behind the caravan,
came running up; he suddenly stood still as if pulled from behind by
the tail, scented; afterwards squeezed into the narrow passage between
th