or the GREAT DESERT, an immense tract of territory in Northern and Central Africa, the most desolate and terrible on the face of the globe. It is bounded on the north by the Barbary States; on the south by Soudan, or the countries watered by the upper course of the Niger, and by the Lower Senegal; and on the east it commences near the left bank of the Nile, and stretches westward to the shores of the North Atlantic Ocean, being nearly the whole breadth of Africa. Its actual extent may be stated as from the fifteenth to the thirtieth parallels of north latitude, and from the thirtieth of east to the fifteenth of west longitude. Its length is thus about three thousand miles, and its breadth is in some parts above a thousand miles. It is by many degrees the largest desert to be found in any part of the world, and it occupies about one fifth of the surface of this part of the globe. Sahara seems to be a table-land little raised above the level of the sea, covered with moving sands, and here and there containing some rocky heights, and valleys, or oases, where the water collects and nourishes thorny shrubs, ferns, and grass. From the defective cultivation of the surrounding countries, and the influence of the prevailing winds, the desert has always been gaining ground, so that in the east some of the Egyptian monuments of antiquity, which at the time of their erection were no doubt unencumbered by the sand, even at their bases, are now covered with it. In the south, likewise, it has encroached on the banks of the Niger and the Senegal; and on the north and north-west the southern provinces of Morocco have been partly usurped by it, so that the streams descending from the Atlas Mountains are either drunk up, or have their courses diverted so as to be rendered comparatively useless; while in the west it has, in some parts, extended a hundred miles into the sea, forming immense sand-banks, destructive to the formation of landing-places. The mountains along the Atlantic Ocean are in no continued chain, but rise up in isolated peaks, and through the open spaces between them the sand is drifted by the winds. Towards the interior they again lose themselves in a plain covered with white and sharp pebbles. From being frequently shifted by winds, the sand extends over the vast plain in a billowy or undulating manner, like the sea when agitated. In its nature it is quartzy and calcareous. The solid fixed rocks which occasionally rise above this mobile surface are sometimes extensive enough to form tracts of country. In the eastern part of the Sahara, the rocks are principally secondary, and for the most part limestone, sandstone, gypsum, and rock-salt, which occasionally appear to be traversed by trap-rocks. At Tegazza, and some other places, a sal-gem, whiter than the purest marble, lies in extensive strata under a bed of rock. Golbery informs us, that on its southern margin he found masses of native iron. The waters of the lakes which here and there occur in the desert are in some instances impregnated with carbonate of soda, in others with muriate of soda or common salt, forming the natron and salt lakes of travellers. The rocks on the seacoast of the Sahara, and the islands that lie along it, are said to be principally composed of igneous rock, and chiefly basalt.

The principal production of Sahara is mineral salt, which, in many places, covers the surface in white glittering crystals, so that at a distance they appear to be rugged fields of snow or ice. This salt constitutes the staple article of the trade of Soudan, and Timbuctoo is indebted to this product of the waste for its existence as well as its prosperity.

The most remarkable feature of this desolate ocean of sand consists in the oases or verdant islands which, at distant and dreary intervals, agreeably break its appalling uniformity. These are formed by springs, which, fed by distant mountains, burst forth amidst the desert solitudes, and, diffusing a partial verdure and fertility, form a strikingly beautiful contrast with the surrounding desolation. They are embellished with flowering shrubs of peculiar beauty. An aromatic plant resembling thyme, the same which bears the grains of zahara, acacias and other thorny shrubs, nettles, and brambles, constitute the ordinary vegetation of these places. Whole tracts are covered with forests of acacia, from which rich gums distil their odours; and groves of the date and lotus also occur, but more rarely. The fruits and berries which they yield constitute the food of whole tribes of men, while the verdure affords a support for animals chiefly of the antelope species. But lions, panthers, and serpents of enormous size, sometimes augment the horrors of these frightful solitudes. Ravens and other birds of prey are likewise often seen hovering over the track of the caravan, ready to dispute with the Moorish dogs for the carcasses of those who have perished in the desert. These oases are frequented by numerous flocks of ostriches, which feed on snails, lizards, and some coarse plants. For a great part of the year the dry and heated air has the appearance of a reddish vapour, and the horizon looks like the fire of a series of volcanoes. The rain, which descends from July to October or November, does not extend its precarious and momentary blessing to all the districts. In some of them rain does not fall for years together, on which occasions the springs also dry up, and a frightful want of water ensues, which drives men and animals to despair. The air during the day is oppressively hot, without a cloud to mitigate the glowing sunshine; and during the night it is disproportionally cool. The natural magic of the Fata Morgana, here often exhibited to the eye of the parched traveller, is provokingly deceptive. Sometimes he sees in the distance what appears almost beyond question to be a sheet of water glittering in the sunbeams. He hastens forward, in hopes of soon allaying his thirst at the welcome lake; but his efforts to reach it are as vain as those of the child to clasp the rainbow. Still his fainting steps pursue; for still the imaginary lake lies before him as lovely and alluring, but as distant, as ever.

It is of course only on the borders of the Sahara that oases on a great scale occur. In the eastern part they are extensive enough to form small kingdoms, generally dependent on some more powerful neighbour. In other parts, particularly the western, they consist merely of one or more detached villages, serving as emporia for the trade carried on by the caravans. And sometimes, especially as we penetrate into the interior of the desert, the oases are merely springs which nourish too scanty a vegetation to admit of inhabitants settling there, but affording supplies of water to the caravans, whose route is determined by the situation of these fountains. Dreary and encompassed with dangers as such abodes must be, every spot on which inhabitants can subsist is occupied; and notwithstanding the perils and sufferings of such travelling, regular journeys are performed across the whole breadth of this desolate region, from Morocco on the north to Timbuctoo on the south.

The only animal fitted for traversing these solitudes as a beast of burden is the camel, which with equal truth and beauty has been designated the ship of the desert. By its patience of hunger and fatigue, by the provision which has been made for its carrying a large supply of water, and by the structure of its hoof, so formed as to glide smoothly over the level sand, it seems expressly designed by nature as a means of communication across these immense wastes. The merchandise which they convey is firmly secured on their backs by means of creeds and otherwise; and for the sake of mutual aid and defence, as well as to relieve the tedium of the route, they proceed in large bodies, occasionally amounting to the number of two thousand. The trade is carried on by merchants inured from their infancy to the hardships which attend such journeys. Their food consists of the milk of the camel, with barley-meal or Indian corn, and a few dates, although the more opulent carry dried flesh and coffee. Water is conveyed in goat-skins, covered with tar for the purpose of preventing evaporation. The caravans, or akkabahs, as the Moors call them, do not proceed in a straight line to their journey's end, but turn in various directions according to the position of the different oases. At each of these the travellers rest and refresh themselves for a day or two, and take in supplies of water. Two great evils are encountered in crossing the desert. The first and most terrible is, when from a peculiarly dry season one or more of the springs happens to fail; and the second is the burning wind, called the samoom, shoom, or simoom. Less than half a century ago a caravan consisting of two thousand persons and eighteen hundred camels, not finding water at the usual places, perished utterly, both men and animals. The vehemence of the wind, which is more like the breath of a furnace than the natural commotion of the atmosphere, raises and rolls before it the waves of red sand, causing the desert so much to resemble a stormy sea, that the Arabs have given it the name of "Bahar billsa-mais," or waterless sea.

Major Denham relates an instance of the terrible effects of the simoom. "The overpowering effect of a sudden sand-wind, when nearly at the close of the desert, often destroys a whole kafila, already weakened with fatigue. The spot was pointed out to us, strewned with bones and dried carcasses, where, the year before, fifty sheep, two camels, and two men, perished from thirst and fatigue, when within eight hours' march of the well which we were anxiously looking for."

Captain Lyon thus describes the appearance of these dead bodies: "We observed many skeletons of animals which had died of fatigue on the desert, and occasionally the grave of some human being. All these bodies were so dried by the extreme heat of the sun, that putrefaction did not appear to have taken place after death. In recently dead animals I could not perceive the slightest offensive smell; and in those long dead, the skin, with the hair on it, remained unbroken and perfect, although so brittle as to break with a slight blow. The sand-winds never cause these carcasses to change their places, as in a short time a slight mound is formed round them, and they become stationary." The fact here noticed of the preservation of the dead bodies in the sand has been observed in other parts of the world, for instance in South America. It appears that the heat of the sun rapidly exhales the natural juices, which prevents the usual process of putrefaction from going on, and thus the carcass is parched into something resembling the well-known mummy of Egypt.

The merchants possess some knowledge of the heavenly bodies, and direct their course by the polar star, often preferring to travel during the clear nights of these climates rather than brave the scorching heat of a tropical sun. This nocturnal travelling, however, has its inconveniences, so that the most part of the journey is performed during the day. The camel-drivers sing as they go along; and as they approach houses, or when the camels seem in danger of dropping down with fatigue, their songs acquire additional spirit and expression, which is said to have the intended effect upon the animals. At four o'clock in the afternoon they pitch their tents and join in prayer. Supper follows this act of devotion, after which they sit down in a circle and converse or recite stories until sleep closes their eyes, and the perils of the desert are forgotten in its unconsciousness.

The coast of Sahara contains some harbours and roadsteads. Those of Rio-do-Ouro and of St Cyprian are formed by large creeks, resembling the mouths of rivers. The Gulf of Ardum, and the Portendic Road, have often been visited by Europeans. On the same line are Cape Bojador and Cape Blanco, which latter is supposed to mark the limit of the discoveries of the Carthaginians. At Hoden, Tisheet or Tegazza, and Taoudeny, in the western region of Sahara, are extensive mines of rock-salt, an article which is wanting in the populous regions of Central Africa, and is consequently in great demand in those quarters. One of the principal depots of salt is Walet, which, by this article, is rendered a place second in importance only to Timbuctoo. Aroun, also, in the very centre of the desert, has become a place of some importance, containing three thousand inhabitants, chiefly by this trade and the passage of caravans. In the heart of Sahara, between Gadamis and Timbuctoo, is the district of Suat or Tuat, inhabited by a mixture of Arabs and Tuaregs, in no respect superior to the rest of the desert tribes. Aghably and Ain-el-Salah, their chief towns, are frequented as caravan stations.