become drier, and the gradual desiccation of the land is attested by the remains of organisms unable to survive under the changed conditions of their environment.
Nevertheless the local populations, accepting the struggle against nature, have Fig. 76. — Barrage of the Hamiz.
constantly endeavoured to preserve their plantations, and "artesian" wells were sunk in North Africa long before the practice was introduced in Europe. But none of these wells "lived" long, some "dying" in five years, while a few prolonged their existence, under favourable conditions, for eighty or even a hundred years. Since 1856, however, scientific methods have replaced the rude processes of the inhabitants everywhere except in the regions still subject to the influence of the marabuts of Temacin. At a depth of 100 feet the engineer, Jus, reached the Bahr Tahtani, or "Lower Sea," which flows beneath the dried-up bed of the Wed Righ, and the inhabitants of the Tamerna oasis, north of Tugurt, beheld with surprise and delight a spring suddenly welling up and yielding over thirty gallons per second. This source received from the marabuts the name of "Well of Peace," to commemorate the treaty of friendship henceforth cemented between the Saharians and the French creators of living waters.
Since this first essay, over a hundred Artesian wells have been sunk in the hydrological basin of the Melghigh, and fresh sources are being constantly developed. One of the most copious is that of the Sidi Amran oasis, in the Wed Righ, north of Tugurt, which yields nearly fifty gallons per second. The wells have an average depth of 230 feet, with a temperature varying from 65° to 78° F. Sudden changes and even a total
