The exploitation of the artesian basin of the Libyan Desert has been in progress for hundreds and thousands of years, and it is probable, therefore, that in the oases-depressions the general average pressure has been very much reduced. At the present time the water-pressures seldom exceed a very few pounds per square inch, so that the static head, or absolute height to which the water will rise, is seldom more than a few metres above the actual surface of the ground. The outlets of the native wells are, unfortunately, of such a nature that it is not possible to make even approximate determinations of pressure; but after taking into account the influence of ground-level on the volume of flow, we still find differences which point to there being considerable variation in the absolute static head in different parts of the oasis—that is to say, the water will rise higher in some places than in others. This is probably partly to be accounted for by variations in the level of the underlying strata and by the presence of faults—for instance, the static head to the west of the central line of disturbance is certainly considerably higher than to the east. In the absence of accurate data, the static head in a district can be approximately gauged from the ground-level and flow of any one of the higher and more isolated wells. The maximum static head judged in this way appears to be 88 metres above sea-level in the Kharga district on the west side of the fault; but in the Headquarters area, to the east of the fault, it can be definitely proved to be very much less. In order to determine the extent of the local variations throughout the district where the recent boring operations have extended, I carried out a number of experiments. For this purpose four bores in different parts of the area were selected, of similar diameters, and of approximately equal depths into the water-sandstone. By means of a flange the casing of each bore was carried vertically upwards, the ordinary outlet being kept shut until the pressure ceased to rise, as indicated by a pressure-gauge. It was then found that in Bore No. 36 the water had risen to 61·6 metres, in Bore No. 38 to 59·55, in Bore No. 42 to 64·26, and in Bore No. 44 to 62·0 metres above sea-level. The average static head in this district may therefore be taken as 61·85 metres. The positions of the four bores in question, with regard to Headquarters, are as follows: No. 36, 7·7 kilometres N.; No. 38, 2·6 kilometres N.W.; No. 42, 1·6 kilometres S.E.; and No. 44, 3·9 kilometres W.N.W. To the north of Meheriq the static head appears to rise, as flowing wells are found up to 76 metres above sea-level (Ain Mohammed Delaib). The water-level at Ain el Ghazâl is even higher (84·56), but this well does not actually run.