The above method is only applicable to bores in which the wooden casing is more or less intact. Where the latter has rotted and allowed the sides of the well to collapse, a much more difficult and complicated procedure is necessary before the discharge can be re-established. In a case of this sort the original rectangular shaft has to be entirely cleared of material, and a new string of casing placed in the exact position occupied by the original pipe of the well. Moreover, the timber of the shaft itself has generally to be repaired or entirely renewed, as otherwise there would be very great danger of the sides collapsing when the material from within was removed. The process is rendered extremely difficult and laborious by reason of the entire work having to be carried on under water. Although a well may have stopped flowing, the passages are never so completely blocked as to altogether prevent the water from rising to within a few feet of the surface, and any excavation made will always be found to become speedily filled with water. The work can, therefore, only be carried out by men who have trained themselves to remain and work under water, and a limited number of these divers are found in most of the Egyptian oases. I have frequently watched and chatted with the divers at work on old wells, both in Dakhla and Kharga. Unlike the usual custom of remunerating men employed on well-cleaning by shares of the resulting water, divers are generally paid in cash at the rate of about a shilling a day, each man receiving his food as well. The descent is always made feet first, hand over hand down a rope stretched from the top to the bottom. When the diver wishes to return to the surface he signals by a motion of the rope to those at the top, who promptly haul him up. The rate of progress depends, of course, on the depth at which the work is proceeding. In a well I once visited near Hindaw, in the oasis of Dakhla, divers were working at a depth of 29 metres. Each man descended six or seven times a day, remaining on each occasion from two to two and a half minutes under water. Work had been in progress here for four years, and the excavation was still 16 or 17 metres from the bottom of the shaft. The excavated material is placed in baskets, which, when full, are drawn up by hand. As soon as the shaft has been cleared to the bottom the new casing is inserted, the intervening space filled in, and the work carried on as in a new bore. Many extinct wells have thus been put into good working order, though in some cases the divers have been unable to overcome the difficulties encountered, and the wells have been finally abandoned after months, or even years, of labour.