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