Mr. Horneman states, that the morning on which he left the _foot of the sand hill_, he entered the Desert which may be considered as “the natural limit of Egypt.” This Desert extends more than 150 G. miles from east to west: its extent southward, is not known, but it probably borders on the Lesser Oasis. Whether it be a part of that great sandy desert of twelve journies across, between the Greater Oasis and Siwah, Mr. Horneman had no opportunity of knowing; as he remained in uncertainty respecting the course of the _Ummesogeir_ hills, southward. This Desert, perfectly flat, and covered with shifting sand, is bounded northward by a chain of bare calcareous hills, running nearly east and west, in the line of our traveller’s route. On the side towards the Desert, they are steep, and are bordered by a remarkable valley or hollow, known to extend from the _neighbourhood_ of the Bahr-bela-ma, to the length of a journey of seven days westward. Its breadth is from one mile, to six; it had much standing water in it, at certain seasons; but when Mr. Horneman saw it (in September 1798,) it had only some small lakes or ponds, at intervals; and in several places, tracts of marshy or swampy land, extending for several miles together. The water of the pools was bitter; but sweet water was found close to them, on digging to the depth of four to six feet. (See above, p. 10.) The caravans in this route, keep along the edge of the valley, availing themselves of its resources of water, every two or three days; but preferring the sandy path, as being best adapted to the feet of the camels. How far the valley extends westwards, is not known to us: whether it terminates at the place where Mr. Horneman ascended the hills of Ummesogeir, (which form a continuation of the range of calcareous hills before-mentioned;) or whether it communicates with those valleys, which contain the Greater or Lesser Oasis. Be it as it will, it seems to partake of the nature of those valleys; being situated at the foot of steep calcareous hills, and below the level of the flat Desert beneath them. It is remarked, that the steep sides of all these ranges face the south or west.[29] In one particular, however, this valley of Mogara, differs very widely from those which contain the Oasis, (although it seems very much akin to that of _Schiacha_; of which more in the sequel,) in that no water springs up to the surface; to which cause we may probably attribute the absence of such tracts of land, as are denominated _Oases_. The springs indeed, appear to me, to be a characteristic feature of the Oases.