For irrigation purposes an ordinary bore-hole or small pit is quite useless, the inflow of water through the pores of this sandstone being too slow to yield a pumping supply. When a large pit is excavated, fissures, through which water is seen to be freely circulating, are nearly always exposed. Experiments show that—provided a sufficiently large collecting-tank is made, measuring, for instance, 5 by 4 metres, and sunk from 1 to 2 metres below the standing water-level—a supply sufficient to yield a continuous discharge of 8 gallons a minute (equivalent to 11,500 gallons per day of twenty-four hours) can frequently be obtained. Moreover, by sinking a bore to a depth of 7 or 8 metres from the bottom of the pit, preferably on one of the fissures, the supply can be increased threefold, the water emerging from the bore in considerable volume, though with insufficient pressure to carry it (in a length of well-casing fixed on the top of the bore-hole) above the level of 55·74. The latter figure may, indeed, be regarded as the static head in this neighbourhood of the water in the Surface-water Sandstone. The fact that from this sandstone we are unable to obtain an artesian well at the surface, but can get flowing water at a depth of a few metres, is an important illustration of the very slight difference in some cases between flowing and non-flowing wells, and of their close connection with, and dependence on, the absolute ground-level. The extent to which this sub-surface source can be drawn on without lowering its level has not yet been determined, though, in a pit alongside Bore No. 2, a ‘saqia’ or Persian waterwheel (a native contrivance adapted for lifting water, worked by oxen or camels), has been working for about eighteen months without appreciably affecting the supply.