522 SAHARA mountains and extending from the Dalles of the Columbia to the Bitter Root mountains, on both sides of the Columbia, and on forks of the Lewis and the Snake or Sahaptin rivers. They have the Selish family on the north and the Shoshones on the south. The family embraces the Nez Perces or Sahaptin proper (see NEZ PEROTS), the Palus, the Tairtla, the Wallawal- las, the Yakamas and Kliketats, and according to some the Waiilatpus or Cayuses. SAHARA, the largest desert in the world, oc- cupying an area estimated at from 1,500,000 to 2,500,000 sq. m., in the N. portion of Africa, across which it extends 8,000 m. from the At- lantic ocean to the valley of the Nile, with a width of 1,000 nf. between Soodan and the countries bordering the Mediterranean sea. As the same sterile region is renewed beyond the Nile, its E. and W. boundaries may be re- garded as coterminous with those of the con- tinent itself, while the 15th and 30th paral- lels of N. latitude mainly form its southern and northern limits. Under the name of the Algerian Sahara, it extends considerably N. of the 30th parallel along the southern base of the Atlas, and closely approaches the Mediter- ranean W. of the gulf of Cabes. Here the marshy depressions known as shotts, of which the so-called Melrir lake is best known, con- stitute a basin into which it has been proposed to admit the waters of the sea by means of a canal. Continuations of the Sahara stretch eastward and northward through Arabia, Per- sia, and central Asia into Mongolia, where they terminate in the desert of Gobi. The great desert of Africa presents an alternation of im- mense burning wastes of loose and moving sand, with tracts of barren rock, stony plains of gravel, many of which are covered with saline deposits, and elevated and rocky plateaus rising into mountains with extensive valleys and expanses of sand between them. The Average elevation of the Sahara above the sea a fi n 9timated at 1,500 ft., although the surface to the 10 * to be depressed in many places be- places,* 16 l eve l f the ocean. Its most moun- buildin' 19 portion lies along the caravan routes houses, anT resiuVand Borneo and Houssa, where ter is furnished, oil" of the table land, begin- cars run to East Sagithe plateau of Hamadab, nected with Detroit ana 000 ft., amid peaks of state by the Michigan Cenining the maximum Pere Marquette, and the Sag38 of Asben, 5,000 St. Louis railroads. Saginaw i the west, called business in furnishing supplies Ihe greatest ex- regions, and possesses large intt Its hills en- mills and salt works in the adjacilong line of The principal manufacturing estetween Cape within the city limits are eight ? portion of mills, three planing mills, sash and c and there ^factories, extensive stave and barr of Fezzan four shingle mills, and eight salt woiibyan des- city contains a national bank, a privng toward several hotels, a central and five ward3nt. (See two weekly newspapers, and Baptistpnly per- pal, German Lutheran, Methodist, Insert, are most numerous. (See OASIS.) The character of the S. border of the Sahara is imperfectly known, but is believed to be mountainous. In the north it is skirted by extensive treeless pasture lands along the base of the Atlas range, reaches the shores of the Mediterranean at the gulf of Sidra, and further E. is bounded by the table land of Barca. A climate of burning aridity prevails on the great desert of Africa. Rain is utterly unknown except in the oases and on the mountains, where it occasionally falls with such violence as to produce torrents that suddenly pour down into the valleys, and almost as suddenly disappear. The sterility of the Sahara is largely attributable to the fact that the prevailing N. E. trade winds which blow over its surface bring it no moisture, having been almost drained of aqueous vapor in their long continental journey over Europe and Asia. On the mountains S. of the Medi- terranean they deposit more than they have collected in their brief passage over that sea. When they reach the heated desert beyond, where the absorptive capacity of the air is greatly increased by the access of temperature, they bear away moisture instead of bringing it. and it is not condensed into rain until it reaches the mountains of central Africa. The Sahara is probably subject to a higher temper- ature than any other region on the globe ; the thermometer there has been known to register 188 F. This terrific heat imparts their dreaded characteristics to the simoom and other simi- lar winds which blow off the desert. (See AFRICA.) Notwithstanding the obstacles to travel offered by the desert, it is constantly crossed on various routes by caravans of tra- ders. In the absence of watercourses, were it not for the camel, well termed in oriental lan- guage "the ship of the desert," these wastes would be impassable to man. Nocturnal ra- diation is extremely rapid, and the nights are usually cold. The geological formation is un- favorable to fertility, and although in some localities a growth of thorny bushes and plants peculiar to the desert is met with, the vast bodies of silicious sand afford little or no nu- triment to vegetation, and their unstable nature is opposed to its development. Even in min- eral productions the desert maintains its char- acter as a barren waste. No useful products are obtained except salt, which is collected by caravans and sold in Soodan. The fauna of the desert proper includes snakes, lizards, scor- pions, and ants ; but the animals of its borders and the oases comprise about 50 species of mammals, including the lion and leopard, the giraffe, and various antelopes. The marked distinction between the faunas of N. and S. Africa, separated by the desert, is explained by the supposition that a portion of the Saha- ra was submerged beneath the sea during the pliocene period of geology. Marine shells have been discovered S. of the Atlas, and lines of sea beach, showing that at no very remote geological period the plains formed the bed
