A study of the contoured map seems to me to be absolutely conclusive on the question at issue, for it indicates clearly that at no time within the geologically recent period can there have been any such continuous channel as has been supposed. Let us try and trace, with the aid of the map, the most likely course along which the ancient Libyan Nile-branch, if ever one existed, must have flowed. Starting from the Nile in the neighbourhood of Dongola, we observe that the lowest possible track is through Sheb towards Kharga. But Sheb can only be reached after passing over some 350 kilometres of desert lying well above the level of the Nile at Dongola, which is about 230 metres above sea. It is, of course, quite conceivable that even within geologically recent times the Nile at Dongola may have been considerably above its present level; so that we may pass over this first difficulty as not being definitely conclusive against the hypothesis we are pursuing. From Sheb to the south end of the Kharga depression there is a drop of about 160 metres, so that up to this point a channel may have been possible. But from here onwards, difficulties come in. If we turn northwards, we soon encounter the north wall of Kharga, rising to 300 metres above sea-level; so there is no continuing that way. Instead, we turn westwards towards Dakhla. But from Kharga we have to pass over ground reaching very nearly to the 200-metre contour for some 80 kilometres to enter the Dakhla depression, where we drop to a level of 119 metres. We have to traverse some 15 kilometres at altitudes above 200 metres to reach Abu Mungar, where the level is 117 metres; then a further 12 kilometres lying above the 200-metre contour to get to Farafra, where the level descends to about 90 metres. To get out of Farafra, we have again to traverse country lying over 200 metres above sea, whether we choose a north-westerly route _viâ_ Sittra to the Qattara depression, or a north-westerly one _viâ_ Baharia to the Wadi Rayan and the Faiyum. Taking the first of these alternatives as being the shorter, we cross some 30 kilometres of ground above the 200-metre level, and a further 120 kilometres lying between the 200- and 100-metre contours, before reaching the Qattara depression. And once we are in the Qattara depression (the lowest point of which is 134 metres below sea), there is no possibility of reaching the Mediterranean except by crossing a considerable tract where the ground-level is over 100 metres above sea-level. A section of the route described, with a comparison-line passing through the present Nile-levels in corresponding latitudes, is shown in the figure below: