_Regenfeld_, it will be remarked, was found to be very nearly in the position assigned to it by Jordan in 1876,[62] and my estimation of the level of the place is only 20 metres higher than Jordan’s. The neighbouring dune I found to be 30 metres high, agreeing exactly with Jordan’s measurement of fifty years previously; and as far as I could judge, the situation of the dune relative to the cairn seems to have remained unchanged through this long interval, showing that there has been at any rate no great lateral displacement of the dunes. The iron tanks left by Rohlfs were quite intact, in spite of their half-century of exposure; they had become covered with a hard dark brown film, apparently of magnetic oxide of iron, not rusted in the ordinary way, a fact which speaks strongly for the dryness of the region. Empty wine- bottles left by the Rohlfs expedition were frosted by the sand-blast wherever they were exposed; but surprisingly little of the glass had been removed in this way. _Pottery Hill_ is the northern one of a pair of nearly conical dark sandstone hills about 40 metres high, which are conspicuous from some distance owing to their situation on a nearly level sand-plain. I gave it its name from the numerous jars which I discovered at its foot in 1917. _Sheb Well_ is a pool of fairly good water in a shallow excavation at the foot of a clump of dom palms, half surrounded by sand-dunes and tamarisk mounds, 240 metres north-north-west of a fort; the latter occupies a fairly conspicuous position on a sandstone hill about 25 metres high. Another well, situated at the foot of a clump of dom palms about 11 kilometres farther north, is called Bir Terfau; this should not, of course, be confused with the Bir Terfawi already mentioned. To the north of Sheb, on the Arbain road, are three other water-sources which I visited in 1925 and of which I determined the approximate positions by a carefully controlled car-traverse: Bir Kassaba, in lat. 22° 41′, long. 29° 55′; Bir Abu Hussein, in lat. 22° 53′, long. 29° 55′; and Bir Murr, in lat. 23° 22′, long. 30° 5′. Bir Kassaba is a pool of good water at the foot of a clump of palms; Bir Abu Hussein, which likewise yields good water, is a small excavation in sand near a hill of pink coarse-grained granite, and usually requires to be dug out afresh by each traveller; Bir Murr, on a little plain surrounded by hills, consists of several holes, with fairly good water, excavated in the sand at the south side of the outcrop of a steeply inclined bed of speckled calcareous sandstone.