‘Egypt is the gift of the Nile.’ But I believe that it is the gift of the Nile in a much larger sense than Herodotus had in his mind when he wrote these words. It is the gift of the Nile in a double sense. The Nile both cut out the valley, and also filled it up with alluvium. The valley filled with alluvium is Egypt. The excavation of the valley was the greater part of the work. That it was formed in this way was suggested to me by its resemblance to the valley of the Platte above Julesburg, as it may be seen even from a car of the Pacific Railway. You there have a wide valley, like Egypt, perfectly flat, bounded on either side by limestone bluffs, sometimes inclined at so precipitous an angle that nothing can grow upon them, excepting, here and there, a conifer or two; and sometimes at so obtuse an angle that the slopes are covered with grass. These varying inclinations reproduce themselves in the bounding ranges of the valley of Egypt. The Platte writhes, like a snake, from side to side of its flat valley, cutting away in one place the alluvium, all of which it had itself deposited, and transporting it to another. It is continually silting up its channel, first in one place, and then in another, with bars and banks, which oblige the stream to find itself a new channel to the right or left. The bluffs, though now generally at a considerable distance from the river, must have been formed by it, when it was working sometimes against one, and sometimes against the other side of the valley; and sometimes also for long periods leaving both, and running in a midway channel. Why should not the Nile have done the same? This supposition is supported by the fact that when you have a soft cretaceous limestone, and rocks that may be easily worn away, the valley of Egypt is wide. When, as you ascend the stream, you pass at Silsiléh into the region of compact siliceous sandstone, the valley immediately narrows. And when you enter the granite region at Assouan, there ceases to be any valley at all. The river has not been able, in all the ages of its existence, to do more than cut itself an insufficient channel in this intractable rock. All this is just what you would expect on the supposition that it was the river that had cut out the valley. We are sure, at all events, of one step in this process. For there is incontrovertible evidence that, in the historical period, the river flowed at a level twenty-seven feet higher than it does at present, as far down as Silsiléh. In several places, down to that point, may be found the Nile alluvium, deposited on the contiguous high ground at that height above the highest level the river now reaches in its annual inundations. There is, besides, the old deserted channel from a little below Philæ to Assouan, into which the river cannot now rise. Here, then, is the evidence of Nature.