A minute or two of climbing brought them out upon the semicircular platform which crowns the rock. Below them on the far side was a perpendicular black cliff, a hundred and fifty feet high, with the swirling, foam-streaked river roaring past its base. The swish of the water and the low roar as it surged over the mid-stream boulders boomed through the hot, stagnant air. Far up and far down they could see the course of the river, a quarter of a mile in breadth, and running very deep and strong, with sleek black eddies and occasional spoutings of foam. On the other side was a frightful wilderness of black, scattered rocks, which were the _debris_ carried down by the river at high flood. In no direction were there any signs of human beings or their dwellings. “On the far side,” said the dragoman, waving his donkey-whip towards the east, “is the military line which conducts Wady Halfa to Sarras. Sarras lies to the south, under that black hill. Those two blue mountains which you see very far away are in Dongola, more than a hundred miles from Sarras. The railway there is forty miles long, and has been much annoyed by the Dervishes, who are very glad to turn the rails into spears. The telegraph wires are also much appreciated thereby. Now, if you will kindly turn round, I will explain, also, what we see upon the other side.” It was a view which, when once seen, must always haunt the mind. Such an expanse of savage and unrelieved desert might be part of some cold and burned-out planet rather than of this fertile and bountiful earth. Away and away it stretched to die into a soft, violet haze in the extremest distance. In the foreground the sand was of a bright golden yellow, which was quite dazzling in the sunshine. Here and there, in a scattered cordon, stood the six trusty negro soldiers leaning motionless upon their rifles, and each throwing a shadow which looked as solid as himself. But beyond this golden plain lay a low line of those black slag-heaps, with yellow sand-valleys winding between them. These in their turn were topped by higher and more fantastic hills, and these by others, peeping over each other’s shoulders until they blended with that distant violet haze. None of these hills were of any height--a few hundred feet at the most--but their savage, saw-toothed crests, and their steep scarps of sun-baked stone, gave them a fierce character of their own. “The Libyan Desert,” said the dragoman, with a proud wave of his hand. “The greatest desert in the world. Suppose you travel right west from here, and turn neither to the north nor to the south, the first houses you would come to would be in America. That make you home-sick, Miss Adams, I believe?” But the American old maid had her attention drawn away by the conduct of Sadie, who had caught her arm by one hand and was pointing over the desert with the other.