[Illustration: _Profile from the Nile at Dongola through the depressions of Kharga, Dakhla, Abu Mungar, Farafra, and Qattara to the Mediterranean. Vertical scale 500 times the horizontal. Total length of section about 1700 kilometres; for more than half this distance the ground-level is seen to be above a line drawn through the levels of the Nile in corresponding latitudes._] Can any one believe that a course of this kind was ever that of a river? To make a through channel would entail deep cutting for more than half the total distance of 1700 kilometres, and would consequently involve excavating hundreds of millions of cubic metres of rock, much of it of considerable hardness. Moreover, it cannot be supposed, in the present state of our knowledge of the region, that more favourable lines of communication exist and have been overlooked. Many depressions doubtless still remain to be discovered; but these, like those already known, will surely prove to be merely local basins. So many cross-country journeys have now been made in various directions through the desert, that it is inconceivable that any continuous channel of the kind we are discussing could possibly have escaped notice. Nor can we reasonably suppose that recent earth-movements have produced the present severance of the various depressions; such movements might perhaps be invoked to account for one or two of the separating elevations, but certainly not for all. We can therefore be absolutely certain that neither the Nile nor any branch of it ever passed through the Libyan Desert to the sea.[11] Even channels of tributary streams to the Nile, such as abundantly survive in the great wadis which enter the Nile valley on its eastern side, are markedly absent in the Libyan Desert. The contours on the map suggest that possibly one such tributary stream may formerly have drained the south-western faces of the great plateau in which the depressions of Dakhla and Kharga form bays, and have entered the Nile somewhere between Aswan and Halfa; but if such a channel ever did exist, its actual traces have long since been obliterated by the smoothing action of subsequent denudation, and only the great escarpment of the plateau which it half encircled remains to tell the tale. _Photographs by Prince Kemal el Din, Dr. Ball, and Mr. Walpole_ [Illustration: 1. _Desert exploration with the ordinary car, requiring help even on flat ground in sandy tracts_] [Illustration: 2. _Caterpillar cars carrying heavy loads over a sand- dune between Bir Terfawi and Gebel Owenat_] [Illustration: 3. _The western wall of the Qattara depression 35 km. S.S.W. of Qara Oasis. Top of cliff about 3 m. and floor of depression 133 m. below sea-level_] [Illustration: 4. _Ain el Hez, Baharia Oasis, irrigated by free flow from well_] [Illustration: 5. _Overlooking the Baharia depression from the pass at its southern end: cars bound for Farafra_]