Twice over irregularities were pointed out by the Sheikh--places where the dead level was broken--as being the sites of former occupancy of that part of the country, the professor discoursing learnedly about the possibility of changes in the surface having taken place and rendered the country barren, while he talked eagerly of how interesting it would have been to encamp at such spots, gather together a score of the fellaheen with shovel and basket, and explore. "But there could never have been cities there," said the doctor. "But there were," replied the professor. "Egypt _is_ not half explored as yet. Out yonder where we passed to-day the land lay lower, and there was the trace of a wady, one of those irregular valleys which doubtless ran towards the Nile. That was once filled with water, but the encroaching sand has filled up and covered everything. Ah, I should like nothing better than to begin digging there. It would not be long before I began to learn who the people were who formed that colony." At last, on the morning of the fifteenth day, when, after a longer night's journey than usual, a halt was made, the faint dawn began to show that the face of the country had undergone a change. Sand there was in plenty, but it was diversified with patches of rocks, some of which were of great elevation, while where the camels began to increase their ordinary rate of speed, a ridge crossed their path, and as it grew lighter the travellers' eyes were greeted by the relief of green bushes, patches of trees, and various traces of this being a place frequented by man. As the sun rose, right across the east there were clouds, which seemed to be very different from those to which they were accustomed, and the reason was soon made plain by a remark from the Sheikh, who explained that the river ran from north to south, about a day's journey eastward, and that if they continued their march a few miles in that direction they would soon come upon signs of cultivation, and a scattered village or two. "And shall we go that way?" asked Frank. "Only as far as the first village, where we can buy grain--corn, and dhurra. Then we strike away again into the desert, along whose borders we must keep. It is safer, and we are less likely to meet with wandering dervish bands. We only come near the river when it is necessary to refill the sacks and give the camels better feed than they can get near the water-holes and fountains." "I see," said Frank, as he glanced at the professor. "To get to the neighbourhood of the Mahdi's people quickly we must go slowly." "Yes, Excellency, it is better so. We stay here two days while three of the young men and three camels go out to buy corn in the villages yonder. There is generally food to be purchased there, for the Nile floods run out widely a little way beyond, and the Khalifa's people have not reached so far as yet." "Is there not the ruin of a great temple somewhere in this direction?"