fully to the disappointment, if the party had been much distressed for want of water. The Sahara is now well known to be advancing from cast to west, besides being in a condition of internal instability, owing to the sand-storms altering the appearance of the surface. The prevailing currents of air that sweep over it are from east to west, and the flying sands travelling in that direction, there enlarge its bounds. The Wandering Sea is one of the Arab titles of a sandy desert.

The Sahara apparently terminates at the valley of the Nile, but the same identical region is prolonged beyond that channel. It embraces nearly the whole of the Arabian peninsula, which, excepting a few enclosed valleys, is a stony and barren tract, and generally an infertile level, presenting great sandy plains, producing little besides the acacia vera, or Egyptian thorn, and a few other plants. North of this is the Syrian

Ruins of Palmyra from the Desert.

desert, which lies between the range of Lebanon and the Euphrates, in the heart of which is the oasis, containing the relics of one of the mysterious cities of antiquity, the Tadmor in the wilderness of a remote time, the Palmyra of a more modern age. It is not difficult to conceive of the effect of its ruins after passing through a waste in many places without a single object showing either life or motion; Corinthian columns of white marble contrasting finely in their snowy appearance with the apparently boundless yellow sands, the monuments of an opulence and art, every other trace of which has vanished with the people by whom it was enjoyed. A day in this desert is admirably described by the author of Eöthen :- "As you are journeying in the interior you have no particular point to make for as your resting-place. The endless sands yield nothing but small stunted shrubs; even these fail after the first two or three days, and from that time you pass over broad plains-you pass over newly-reared hills-you pass through valleys that the storm of the last week has dug; and the hills and the valleys are sand, sand, sand, and only sand, and sand, and sand again. The earth is so sandy, that your eyes turn towards heaven towards heaven, I mean, in the sense of sky. You look to the sun, for he is your task-master, and by him you know the measure of the work that you have done,

and the measure of the work that remains for you to do; he comes when you strike your tent in the early morning, and then, for the first hour of the day, as you move forward on your camel, he stands at your near side, and makes you know that the whole day's toil is before you then for a while, and for a long while, you see him no more for you are veiled and shrouded, and dare not look upon the greatness of his glory; but you know where he strikes over head by the touch of his flaming sword. No words are spoken; but your Arabs moan, your camels sigh, your skin glows, your shoulders ache; and for sights you see the pattern and web of the silk that veils your eyes, and the glare of the outer light; but conquering Time marches on, and by and by the descending sun has compassed the heaven, and now softly touches your right arm, and throws your lank shadow over the sand, right along on the way to Persia." Beyond the Euphrates to the Tigris, with the exception of slips along the two rivers, the country is a desert of burning sands and sterile gypsum, thickly studded with saline and sulphurous pools; and farther eastward the zone of deserts may be traced through Persia, Grand Tartary, and the great central plateau of Asia, extending thus in an almost continuous band of varying breadth from the Atlantic Ocean to the wall of China. Analogous phenomena to those of the Sahara-the mirage and encroaching sands-are displayed through the greater part of this zone, which proceeds in a circle, the arc of which is directed towards the south, through the whole of the ancient world. Especially in some regions of south-western Asia has the dry element sensibly advanced. Once rich and blooming territories, celebrated by the Persian poets as paradisiacal, the theatre of heroic deeds, the seat of political power and intellectual culture, the site of cities which in size and splendour were second to none in Asia, have been visited by the moveable sand, leaving but few evidences of former grandeur and fertility apparent. At Samarcand and Bokhara, celebrated sovereign cities, from which, in the middle ages, bold and chivalrous princes overspread the East with their flying squadrons, the sands have with difficulty been kept at bay. The river Sihun has been compelled to alter its course, and the mighty Oxus of the ancients, according to historical evidence, has lost its Caspian arm in a struggle with the desert. Setting aside the fertile oases, Humboldt supposes the area of the sandy deserts, leaving out those of central Asia, to be 300,000 square leagues. Those of the Tartarian table-land cannot be less than 100,000 more, and adding 100,000 for similar tracts in Midland and Southern Africa, with some other districts, we have a grand total of half a million of square leagues of such surface in the Old World; a space equal to the whole extent of Europe.

The deserts to which the preceding notices refer, are for the most part hot sandy districts, or experience great alternations of heat and cold. Independently of these, there are cold tracts of lowland, chiefly found in the northern regions of Asia. From the declivities of the Ural on the west, to the coast of Kamtschatka on the east, and from the foot of the Altaian Mountains on the south, to the icy margin of the Arctic Ocean on the north, there is a country almost as large as Europe, a melancholy desert, in which, in latitude 67°, the growth of trees ceases altogether; and a little higher up the soil is frozen the whole year through, some few inches of the surface alone being subject to an annual thaw: but at a short distance from the surface, throughout Siberia, a bottom of perpetually frost-bound soil is met with. Gmelin the elder, in his travels, states that shortly after the foundation of the town of Yakutsk, in lat. 62° north, at the end of the seventeenth century, the soil of that place was found to be frozen at a depth of ninety-one feet, and that the people were compelled to give up the design of sinking a well, a statement corroborated in our days by the travels of Erman and Humboldt. Until very lately nothing was known respecting the thickness of the frozen surface; but within these few years a merchant of the name of Schargin, having attempted to sink a well at Yakutsk, was

about to abandon the project in despair of obtaining water, when Admiral Wrangel persuaded him to continue his operations till he had perforated the whole stratum of ice. This was done, and at the depth of 382 feet the soil was found very loose, and the temperature of the earth was 31° Fahrenheit. The external appearance of these cold districts is admirably depicted by a writer quoted by Berghaus. With painful feelings, he states, the traveller observes the trees diminishing in height the nearer he approaches the icy sea. At ninety German miles from the sea, erect and lofty larch trees afford a veil to expiring nature, but from this point their number diminishes, and they become small and crippled. The coating of moss that covers the tree is thicker than the stem itself; but nothing can save it from the destroying breath of the north. Some thin birches endeavour to contend against this fearful foe, but they perish when scarcely sprung from the bosom of the earth, and 70° latitude may be assigned as the limit of the growth of trees. It is only the moss, the true child of the north, which thrives and blooms even in the midst of winter, and scantily covers a soil which has been barren for thousands of years. From the last tree to the frozen ocean extends an enormous desert covered with lakes and lagunes. Some of the lakes are large and deep, and rich in fish, their lofty banks consisting of level beds of earth and ice, the ice covering the earth. Throughout this region a deathlike silence reigns, seldom interrupted except by the summer birds of passage.

We now proceed to notice the flat lands of the New Continent. A large portion of South America is only slightly raised above the level of the ocean. Supposing, as the effect of some particular attraction, the waters of the Atlantic to be raised fifty fathoms at the mouth of the Orinoco, and two hundred fathoms at that of the Amazon, the flood would cover over more than one-half of that part of the New World, and the billows of the sea would dash against the eastern slope or foot of the Andes, which is now nearly 2000 miles from the coast of Brazil. Comparatively low transverse ridges, running east and west, divide South America into three great districts. Through the northern district the Orinoco flows; through the central, the Amazon; and through the southern, the La Plata. The country on each side of these rivers consists of enormous levels, to which the terms Llanos, Selvas, and Pampas, are applied, distinguishing the regions bordering on these mighty streams, in the order in which they have been named.

The Llanos border on the Orinoco, and are plains, including the vast area of 260,000 square miles, at the mean height of 200 feet above the level of the sea, sluggishly therefore bearing tributary streams to the great watercourse. The name is an abbreviation of loca plana, and was applied to them by the first Spanish conquerors, on account of their singular flatness. Humboldt has described the Llanos with great felicity, and presents us with the following graphic picture :-"The sun," he thus commences, "on our entrance into the basin of Llanos, stood almost in the zenith; the ground, wherever it was naked and destitute of plants, was of a temperature which attained 48 or 50 degrees. No breeze was perceptible at the height on which we were sitting on our mules, yet there arose, in the midst of this apparent repose, an incessant cloud of dust driven by light breaths of wind which swept only the surface of the ground, and produced differences of temperature, which were imparted to the naked sand and the spots of grass. These sandwinds increase the suffocating heat of the air. Every grain of sand, hotter than the atmosphere which surrounds it, beams on all sides, and it becomes difficult to measure the temperature without the grains of sand beating against the ball of the thermometer. All around us, the plains seemed to rise to heaven, and this vast and silent desert appeared to our eyes like a sea which is covered with sea-weed, or the algae of the deep sea. According to the inequality of the mass of vapour floating in the atmosphere, and the alternating temperature of the breezes contending against each other, was the appearance of the horizon; in some places clear and sharply defined, in others wavy, crooked, and, as it