The cavity where this sheet of water had collected formed a very slight depression in the meadow-ground, it being almost flat; the water, to all appearance, had already decreased considerably, and only in a few places presented an open sheet, being in general closely overgrown with rank grass and tall reeds. I followed it to a considerable distance towards the N.N.W., till I was obliged by the thick covert to retrace my steps, and then turned westward. The far larger extension of the water during the rainy season was sufficiently indicated by the luxuriant growth of trees. I crossed it at a spot where it was not so extensive, and found the bottom of it extremely muddy, which made the passage rather difficult, though the water was only two and a half feet deep. The indented outlines of its shores greatly distinguished it from those more complete and regular-shaped ngáljams which, in the course of time, I had an opportunity of visiting, not only in those extensive plains between the river Bénuwé and Shári, but also in the regions of the middle course of the so-called Niger; for, in the quarters just mentioned, these shallow waters, or meadow-waters, often stretch out, in a straight or regularly-sweeping line, like artificial canals, to an immense distance,—especially that most interesting sheet of water three days west of Timbúktu, the “Áraf-n-áman,” or Rás el má. Of quite a different nature is the character of the famous Bahar el Ghazál, which joins the Tsád on the north-eastern side, being a broad sandy valley girt by a rich border of vegetation. This peculiar valley, which it was not our destiny to become acquainted with by ocular inspection, formed the subject of conversation with the vizier on Sunday evening; and a disputation arose, of so scientific a character that it might have silenced all those who scoff at the uncivilized state of the population of these regions. To be sure, the two principal persons in this conversation were Arabs; but their forefathers had been settled in these regions for at least ten generations.