Although the ground on which we slept was not many yards square, and there was little or nothing on it to eat, the poor animals, loose as they were, did not venture to trespass on the adamantine plain by which they were on all sides surrounded.

On the 27th we continued onwards, obliged to keep the course by taking bearings on any prominent though trifling object in front.  At ten miles there was a sensible fall of some few feet from the level of the Stony Desert, as I shall henceforth call it, and we descended into a belt of polygonum of about two miles in breadth, that separated it from another feature, apparently of equal extent but of very different character.  This was an earthy plain, on which likewise there was no vegetation; resembling in appearance a boundless piece of ploughed land, on which floods had settled and subsided—­the earth seemed to have once been mud and then dried.  It had been impossible to ascertain the fall or dip of the Stony Desert, but somewhat to the west of our course on the earthy plain there were numerous channels, which as we advanced seemed to be making to a common centre towards the N.E.  Here and there a polygonum bush was growing on the edge of the channels; and some of them contained the muddy dregs of what had been pools of water.  Over this field of earth we continued to advance almost all day, without knowing whether we were getting still farther into it, or working our way out.  About an hour before sunset, this point was settled beyond doubt, by the sudden appearance of some hills over the line of the horizon, raised above their true position by refraction.  They bore somewhat to the westward of north, but were too distant for speculation upon their character.  It was very clear, however, that there was a termination to the otherwise apparently boundless level on which we were, in that direction, if not in any other.  Our view of these hills was but transient, for they gradually faded from sight, and in less than ten minutes had entirely disappeared.  Shortly afterwards some trees were seen in front, directly in the line of our course; but, as they were at a great distance, it was near sunset before we reached them; and finding they were growing close to a small channel (of which there were many traversing the plain) containing a little water, we pulled up at them for the night, more especially as just at the same moment the hills, before seen, again became visible, now bearing due north.  To scramble up into the box-trees and examine them with our telescopes was but the work of a moment, still it was doubtful whether they were rock or sand.  There were dark shadows on their faces, as if produced by cliffs, and anxiously did we look at them so long as they continued above the horizon, but again they disappeared and left us in perplexity.  They were, however, much more distinct on the second occasion, and Mr. Browne made out a line of trees, and what he thought was grass on our side of them.