The soil is soft white sand, very trying to the strength of the oxen, as the wheels sink into it over the felloes and drag heavily.

At Serotli we found only a few hollows like those made by the buffalo and rhinoceros when they roll themselves in the mud.

In a corner of one of these there appeared water, which would have been quickly lapped up by our dogs, had we not driven them away.

And yet this was all the apparent supply for some eighty oxen, twenty horses, and about a score of men.

Our guide, Ramotobi, who had spent his youth in the Desert, declared that, though appearances were against us, there was plenty of water at hand.