Cleopatra. Abbott Jacob
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of animal and vegetable life shut him out, in some measure, from regions which an excess of heat and moisture render too prolific, the total absence of them still more effectually forbids him a home in these. They become, therefore, vast wastes of dry and barren sands in which no root can find nourishment, and of dreary rocks to which not even a lichen can cling.
The most extensive and remarkable rainless region on the earth is a vast tract extending through the interior and northern part of Africa, and the southwestern part of Asia. The Red Sea penetrates into this tract from the south, and thus breaks the outline and continuity of its form, without, however, altering, or essentially modifying its character. It divides it, however, and to the different portions which this division forms, different names have been given. The Asiatic portion is called Arabia Deserta; the African tract has received the name of Sahara; while between these two, in the neighborhood of Egypt, the barren region is called simply the desert. The whole tract is marked, however, throughout, with one all-pervading character: the absence of vegetable, and, consequently, of animal life, on account of the absence of rain. The rising of a range of lofty mountains in the center of it, to produce a precipitation of moisture from the air, would probably transform the whole of the vast waste into as verdant, and fertile, and populous a region as any on the globe.
As it is, there are no such mountains. The whole tract is nearly level, and so little elevated above the sea, that, at the distance of many hundred miles in the interior, the land rises only to the height of a few hundred feet above the surface of the Mediterranean; whereas in New Grenada, at less than one hundred miles from the sea, the chain of the Andes rises to elevations of from ten to fifteen thousand feet. Such an ascent as that of a few hundred feet in hundreds of miles would be wholly imperceptible to any ordinary mode of observation; and the great rainless region, accordingly, of Africa and Asia is, as it appears to the traveler, one vast plain, a thousand miles wide and five thousand miles long, with only one considerable interruption to the dead monotony which reigns, with that exception, every where over the immense expanse of silence and solitude. The single interval of fruitfulness and life is the valley of the Nile.
There are, however, in fact, three interruptions to the continuity of this plain, though only one of them constitutes any considerable interruption to its barrenness. They are all of them valleys, extending from north to south, and lying side by side. The most easterly of these valleys is so deep that the waters of the ocean flow into it from the south, forming a long and narrow inlet called the Red Sea. As this inlet communicates freely with the ocean, it is always nearly of the same level, and as the evaporation from it is not sufficient to produce rain, it does not even fertilize its own shores. Its presence varies the dreary scenery of the landscape, it is true, by giving us surging waters to look upon instead of driving sands; but this is all. With the exception of the spectacle of an English steamer passing, at weary intervals, over its dreary expanse, and some moldering remains of ancient cities on its eastern shore, it affords scarcely any indications of life. It does very little, therefore, to relieve the monotonous aspect of solitude and desolation which reigns over the region into which it has intruded.
The most westerly of the three valleys to which we have alluded is only a slight depression of the surface of the land marked by a line of oases. The depression is not sufficient to admit the waters of the Mediterranean, nor are there any rains over any portion of the valley which it forms sufficient to make it the bed of a stream. Springs issue, however, here and there, in several places, from the ground, and, percolating through the sands along the valley, give fertility to little dells, long and narrow, which, by the contrast that they form with the surrounding desolation, seem to the traveler to possess the verdure and beauty of Paradise. There is a line of these oases extending along this westerly depression, and some of them are of considerable extent. The oasis of Siweh, on which stood the far-famed temple of Jupiter Ammon, was many miles in extent, and was said to have contained in ancient times a population of eight thousand souls. Thus, while the most easterly of the three valleys which we have named was sunk so low as to admit the ocean to flow freely into it, the most westerly was so slightly depressed that it gained only a circumscribed and limited fertility through the springs, which, in the lowest portions of it, oozed from the ground. The third valley—the central one—remains now to be described.
The reader will observe, by referring once more to the map, that south of the great rainless region of which we are speaking, there lie groups and ranges of mountains in Abyssinia, called the Mountains of the Moon. These mountains are near the equator, and the relation which they sustain to the surrounding seas, and to currents of wind which blow in that quarter of the world, is such, that they bring down from the atmosphere, especially in certain seasons of the year, vast and continual torrents of rain. The water which thus falls drenches the mountain sides and deluges the valleys. There is a great portion of it which can not flow to the southward or eastward toward the sea, as the whole country consists, in those directions, of continuous tracts of elevated land. The rush of water thus turns to the northward, and, pressing on across the desert through the great central valley which we have referred to above, it finds an outlet, at last, in the Mediterranean, at a point two thousand miles distant from the place where the immense condenser drew it from the skies. The river thus created is the Nile. It is formed, in a word, by the surplus waters of a district inundated with rains, in their progress across a rainless desert, seeking the sea.
If the surplus of water upon the Abyssinian mountains had been constant and uniform, the stream, in its passage across the desert, would have communicated very little fertility to the barren sands which it traversed. The immediate banks of the river would have, perhaps, been fringed with verdure, but the influence of the irrigation would have extended no farther than the water itself could have reached, by percolation through the sand. But the flow of the water is not thus uniform and steady. In a certain season of the year the rains are incessant, and they descend with such abundance and profusion as almost to inundate the districts where they fall. Immense torrents stream down the mountain sides; the valleys are deluged; plains turn into morasses, and morasses into lakes. In a word, the country becomes half submerged, and the accumulated mass of waters would rush with great force and violence down the central valley of the desert, which forms their only outlet, if the passage were narrow, and if it made any considerable descent in its course to the sea. It is, however, not narrow, and the descent is very small. The depression in the surface of the desert, through which the water flows, is from five to ten miles wide, and, though it is nearly two thousand miles from the rainy district across the desert to the sea, the country for the whole distance is almost level. There is only sufficient descent, especially for the last thousand miles, to determine a very gentle current to the northward in the waters of the stream.
Under these circumstances, the immense quantity of water which falls in the rainy district in these inundating tropical showers, expands over the whole valley, and forms for a time an immense lake, extending in length across the whole breadth of the desert. This lake is, of course, from five to ten miles wide, and a thousand miles long. The water in it is shallow and turbid, and it has a gentle current toward the north. The rains, at length, in a great measure cease; but it requires some months for the water to run off and leave the valley dry. As soon as it is gone, there springs up from the whole surface of the ground which has been thus submerged a most rank and luxuriant vegetation.
This vegetation, now wholly regulated and controlled by the hand of man, must have been, in its original and primeval state, of a very peculiar character. It must have consisted of such plants only as could exist under the condition of having the soil in which they grew laid, for a quarter of the year, wholly under water. This circumstance, probably, prevented the valley of the Nile from having been, like other fertile tracts of land, encumbered, in its native state, with forests. For the same reason, wild beasts could never have haunted it. There were no forests to shelter them, and no refuge or retreat for them but the dry and barren desert, during the period of the annual inundations. This most extraordinary valley seems thus to have been formed and preserved by Nature herself for the special possession of man. She herself seems to have held it in reserve for him from the very morning of creation, refusing admission into it to every plant and every animal that might hinder or disturb his occupancy and control. And if he were to abandon it now for a thousand years, and then return to it once more, he would find it just as he left it, ready for his immediate possession. There would be no wild beasts that he must first expel, and no tangled forests