At half past four they alighted in a vast plain, bounded on all sides by low sandy hills, which seemed to have been just produced. These hillocks were from seven to thirteen feet high, formed into perfect cones, with very sharp points and well-proportioned bases. The sand was of an inconceivable fineness, having been the sport of hot winds for thousands of years. "There could be no doubt," says Bruce, "that the day before, when it was calm, and we suffered so much by the simoom between El Mout and Chiggre, the wind had been raising pillars of sand in this place, called Umdoom; marks of the whirling motion of the pillars were distinctly seen in every heap, so that here again, while we were repining at the simoom, Providence was busied keeping us out of the way of another scene, where, if we had advanced a day, we had all of us been involved in inevitable destruction." On the 18th they left Umdoom at seven in the morning, their course being N., a little inclined to W. At nine o'clock Idris pointed to some sandy hillocks, where the ground seemed to be more elevated than the rest; and he told Bruce that one of the largest caravans which ever came out of Egypt was there buried with sand, to the number of some thousands of camels. At five o'clock in the evening they alighted at an Oasis called Terfowey, full of trees and grass. As soon as they had chosen a proper place where the camels could feed, they unloaded the baggage, and sent the men to clean the well and wait the filling of the skins. They then lighted a large fire, for the nights felt excessively cold, though the thermometer was at 53°; and that degree of cold occasioned Bruce inexpressible pain in his feet, which were now swelled to a monstrous size, inflamed, and excoriated. The camels were always fastened by the feet, and the chain secured by a padlock, lest they should wander in the night, or be stolen or carried off. While Bruce was occupied in deep thought, he heard the chain of the camels clink, as if somebody was unloosening them, and then, by the gleam of the fire, he distinctly saw a man pass swiftly by, stooping as he went along, his face almost close to the ground. A little time after this he heard another clink of the chain, as if from a sharp blow, and immediately after a movement among the camels. He instantly rose, and called out in a threatening tone in Arabic. Mohammed, Idris's nephew, hearing Bruce's voice, came running up from the well to see what was the matter. They went down together to the camels, and, upon examination, found that the links of one of the chains had been broken, but the opening was not large enough to let the whole link through. A hard blue stone was also driven through a link of one of the chains of another camel, and left sticking there, the chain not being entirely broken through; they saw, besides, the print of a man's feet on the sand; and they found that several articles belonging to the party had been stolen.