To prepare a map showing the contours of the static water-surface, I took a graticuled sheet and plotted the above-scheduled points on it in their ascertained geographical positions, affixing the adopted level to each. To get points on the various contours at vertical intervals of 100 metres, I joined each pair of points on the map by a pencil line, and then, by interpolation from the terminal levels, found the points on this line where the various contours crossed it, on the assumption of a uniform gradient between the terminal points. Many of the lines thus drawn of course crossed each other, so that interpolation of the static level at the point of their intersection gave two values for the same place. But their agreement was wonderfully close, considering the fewness and the scattered nature of the datum-points, and this went a long way to encourage me in the belief that the hypothesis on which I had been working, namely, that of an underground water-connection between all the points included in my list, was correct. I found that the contours of the static water-surface could be approximately represented by a series of smooth curves, as shown (on a reduced scale) in the outline map below. Apart from the general smoothness of the curves, especially in the south-west, where it may in part be due to the scantiness of control- points, the most striking thing on this outline map is the north- eastward projection of the 100-metre static contour, where it runs out so as to include Baharia Oasis. The reasons for this projection are obviously the efflux of water, on the one hand north-westwards into the great Qattara depression, and on the other hand into the Nile at Dakka. The indentation of the 400-metre contour near Kufra is likewise explained by the withdrawal of water from the wells of that oasis. The general parallelism of the curves in the south-western part of the map, showing a gradual rise in a south-westerly direction towards the Erdi and Ennedi country (which, as I have already stated, is the most probable source of the underground water) is strikingly apparent. I have not been able to extend the contours far to the east and west of Merga, for lack of control-points. It is much to be hoped that some future traveller will determine the water-levels at Selima and Lagia, which would enable the static contours to be extended into the region between Merga and Dongola; provided, of course, that an examination of the water-sources at these places proves their supplies to be artesian.