It will readily be admitted that this method of sinking wells is in many respects well adapted to the local conditions obtaining in such isolated localities as the oases, where time is of little consequence to the inhabitants. The completed wells are frequently equal in almost every respect to those put down by means of the most up-to-date appliances; in fact, the only objections to the method are its slowness, the limited depth to which it is applicable, and the difficulty of fixing to the wooden casing satisfactory appliances for regulating the discharge. The patience and industry of the inhabitants of the oases are well exemplified by their unceasing attempts to maintain undiminished the water-supply on which their very existence depends. The population must always have borne a direct ratio to the total discharge of the wells, as on the latter depends the amount of food-supplies which can be raised. At no period, as far as we can judge, has the output of the wells been greater than the requirements, and it is probable that there has always been a population somewhat in excess of that which could be supported by local products, the surplus portion being disposed of by emigration to the Nile Valley. The methods of dealing with wells in which the flows have diminished or altogether ceased are of considerable interest, as they have given rise to a class of men called ‘ghattasin’ (divers), which one would never have expected to find in such remote and arid localities as the oases of the Libyan Desert. It is seldom that the poorer inhabitants can command the use of a hand-rig for the cleaning of their wells, so that they usually have recourse to appliances of the most primitive description. Perhaps the simplest form consists of a short iron rod, a sort of crowbar or jumper, suspended from a palm-fibre rope, and with a tiny basket attached to the lower end. In some cases the end of the jumper is itself fashioned into the form of a cup, so that the basket of plaited grass or palm-leaf can be dispensed with. The rod is worked up and down in the bore, so as to stir up the sand and clay at the bottom, which settles in the basket or cup, and is periodically hoisted to the surface. The rope is worked over a wooden roller fixed alongside the mouth of the well, a contrivance which enables the up-and-down motion to be given with a minimum of energy and friction. The process is often continued for years, the material which can be removed in a day only amounting to a few handfuls.