In the reclamation operations conducted in the oasis of Kharga during the last two or three years, both hand and steam boring rigs have been employed, steel casing being used for all wells. The cost per foot drilled is somewhat in favour of the hand-rigs, but the rate of progress is far more rapid in the case of the steam-driven machines. The method used with the hand-machines is the same in principle as that employed by the natives and already described, with the exception that the preliminary excavation is dispensed with, the bore being drilled from the surface and lined with metal casing down to the Water-bearing Sandstones. The casing is driven by means of a heavy weight, or ‘monkey,’ attached to the boring-rod. The steam-rigs used are of American manufacture, and of the design usually employed in the oil-fields of the United States. The method is a modern adaptation of a practice employed from very early times in China, free-falling tools attached to a flexible rope being used in place of a solid iron rod. The actual drilling tool, which is of great weight, is suspended from a cable, and worked by steam-power in such a way as to give a rapid succession of blows of such force as to cut out a circular hole through the hardest of rocks. The outfit consists essentially of a very high derrick, a large drum on which the cable is wound, and a specially-designed engine worked by steam, the boiler in which the latter is generated being usually placed on a separate carriage. A second and smaller drum is provided for a fine wire rope, which is used with various forms of sand-pump for cleaning out the loose sand or sludge formed by the drilling tool. [Illustration: A STEAM BORING RIG.] [Illustration: A HAND BORING RIG.] These steam-rigs necessitate the employment of skilled drillers, and are, moreover, with difficulty kept in proper repair in out-of-the-way localities. Their initial cost is high; they are extremely cumbersome to drag from one site to another over the soft surface of the desert, and they consume a large quantity of fuel. These drawbacks are, however, partly, if not entirely, counterbalanced by the rapidity with which the work can be carried out, the average rate of progress under the conditions met with in the oasis being 5 to 7 metres per ‘shift’ of eight or ten hours. In the water-sandstones I have known Mr. B. F. Whiting, who was recently my drilling superintendent in the oasis, carry a bore down as much as 20 or 25 metres in a single shift. Breakdowns are, of course, not infrequent with this system of boring, but the American drillers are remarkably proficient in the recovery of lost tools. CHAPTER XIV THE CONTEST BETWEEN MAN AND WIND-BORNE SAND