The range of temperature is exceed ingly great: often the thermometer falls from considerably more than F. during the day to just below freezing point at night. In the W. of the Sahara the daily average is 85° in the shade in the month of May. Rain does fall in cer tain parts of the Sahara with more or less frequency; but in most districts on the average after intervals of two to five years.
The plant life is very rich in the oases, the date palm, which has its home in these regions, being the most valuable possession of these fertile spots. But fruit trees, as oranges, lemons, peaches, figs, pomegranates, etc., are also grown, with cereals, rice, durrha, millet, and such like food crops. In the desert regions the plant life is confined principally to tam arisks, prickly acacias and similar thorny shrubs and trees, salsolace, and coarse grasses. The animals most commonly met with include the giraffe, two or three kinds of antelope, wild cattle, the wild ass, desert fox, jackal, hare, lion (only on the borders of the desert), ostrich, desert lark, crow, viper, and python. The people keep as domestic animals the camel, horse, sheep, and goat.
The human inhabitants, who are esti mated altogether at about 2,000,000, con sist of Moors, Tuareg, Tibbu, Negroes, Arabs, and Jews. The Moors and Tuareg are both Berbers; the former live between Morocco and Senegal, the latter in the middle, S. of Algeria and Tunis. The Tuareg are great traders, and control the principal caravan routes. The Tibbu, who number about 200,000, occupy the oases between Fezzan and Lake Tchad.
The Arabs of pure stock are very few; they have become mixed with the Berbers and the Negroes. The most valuable products of the Sahara are dates and salt, the latter collected on the salt pans, and made from the rock-salt of the Tau deni in the W., and of Kawar (Bilma) in the E.; the remaining products are horses, soda, and a little saltpeter. But for many long years there has been a very active trade carried on by caravans be tween the central Sudan and Niger coun tries and the Mediterranean states, the ivory, ostrich feathers, gums, spices, musk, hides, gold dust, indigo, cotton, palm oil, Shea butter, kola nuts, ground nuts, silver, dates, salt, and alum of the interior lands being exchanged for the manufactured wares (textiles, weapons, gunpowder, etc.) of European countries.
Scientific men have eagerly discussed the possibility of reclaiming the Sahara from the arid desolation to which such a vast proportion of its surface is now abandoned. One scheme has been carried out with success in limited areas. It con sists in boring of artesian wells, and with the water so obtained irrigating the soil in the vicinity. This method of reclaim ing the desert has been prosecuted by the French with great energy since 1856. Water is generally found at depths vary ing from 10 to 300 feet, and in great abundance. Wherever these wells have been bored the date palm groves and the orchards have increased greatly in extent, and the population has become much denser.