The sources of the Nile[1] are unascertained, and, travelling as it does for an immense distance through deserts and burning sands, it is only known to us by common report, having neither experienced the vicissitudes of warfare, nor been visited by those arms which have so effectually explored all other regions. It rises, so far indeed as King Juba was enabled to ascertain, in a mountain[2] of Lower Mauritania, not far from the ocean; immediately after which it forms a lake of standing water, which bears the name of Nilides[3]. In this lake are found the several kinds of fish known by the names of alabeta[4], coracinus, and silurus; a crocodile also was brought thence as a proof that this really is the Nile, and was consecrated by Juba himself in the temple of Isis at Cæsarea[5], where it may be seen at the present day. In addition to these facts, it has been observed that the waters of the Nile rise in the same proportion in which the snows and rains of Mauritania increase. Pouring forth from this lake, the river disdains to flow through arid and sandy deserts, and for a distance of several days' journey conceals itself; after which it bursts forth at another lake of greater magnitude in the country of the Massæsyli[6], a people of Mauritania Cæsariensis, and thence casts a glance around, as it were, upon the communities of men in its vicinity, giving proofs of its identity in the same peculiarities of the animals which it produces. It then buries itself once again in the sands of the desert, and remains concealed for a distance of twenty days' journey, till it has reached the confines of Æthiopia. Here, when it has once more become sensible of the presence of man, it again emerges, at the same source, in all probability, to which writers have given the name of Niger, or Black. After this, forming the boundary-line between Africa and Æthiopia, its banks, though not immediately peopled by man, are the resort of numbers of wild beasts and animals of various kinds. Giving birth in its course to dense forests of trees, it travels through the middle of Æthiopia, under the name of Astapus, a word which signifies, in the language of the nations who dwell in those regions, "water issuing from the shades below." Proceeding onwards, it divides[7] innumerable islands in its course, and some of them of such vast magnitude, that although its tide runs with the greatest rapidity, it is not less than five days in passing them. When making the circuit of Meroë, the most famous of these islands, the left branch of the river is called Astobores[8], or, in other words, "an arm of the water that issues from the shades," while the right arm has the name of Astosapes[9], which adds to its original signification the meaning of "side[10]." It does not obtain the name of "Nile" until its waters have again met and are united in a single stream; and even then, for some miles both above and below the point of confluence, it has the name of Siris. Homer has given to the whole of this river the name of Ægyptus, while other writers again have called it Triton[11]. Every now and then its course is interrupted by islands which intervene, and which only serve as so many incentives to add to the impetuosity of its torrent; and though at last it is hemmed in by mountains on either side, in no part is the tide more rapid and precipitate. Its waters then hastening onwards, it is borne along to the spot in the country of the Æthiopians which is known by the name of "Catadupi[12];" where, at the last Cataract[13], the complaint is, not that it flows, but that it rushes, with an immense noise between the rocks that lie in its way: after which it becomes more smooth, the violence of its waters is broken and subdued, and, wearied out as it were by the length of the distance it has travelled, it discharges itself, though by many mouths[14], into the Egyptian sea. During certain days of the year, however, the volume of its waters is greatly increased, and as it traverses the whole of Egypt, it inundates the earth, and, by so doing, greatly promotes its fertility.

There have been various reasons suggested for this increase of the river. Of these, however, the most probable are, either that its waters are driven back by the Etesian winds[15], which are blowing at this season of the year from an opposite direction, and that the sea which lies beyond is driven into the mouths of the river; or else that its waters are swollen by the summer rains of Æthiopia[16], which fall from the clouds conveyed thither by the Etesian winds from other parts of the earth. Timæus the mathematician has alleged a reason of an occult nature: he says that the source of the river is known by the name of Phiala, and that the stream buries itself in channels underground, where it sends forth vapours generated by the heat among the steaming rocks amid which it conceals itself; but that, during the days of the inundation, in consequence of the sun approaching nearer to the earth, the waters are drawn forth by the influence of his heat, and on being thus exposed to the air, overflow; after which, in order that it may not be utterly dried up, the stream hides itself once more. He says that this takes place at the rising of the Dog-Star, when the sun enters the sign of Leo, and stands in a vertical position over the source of the river, at which time at that spot there is no shadow thrown. Most authors, however, are of opinion, on the contrary, that the river flows in greater volume when the sun takes his departure for the north, which he does when he enters the signs of Cancer and Leo, because its waters then are not dried up to so great an extent; while on the other hand, when he returns towards the south pole and re-enters Capricorn, its waters are absorbed by the heat, and consequently flow in less abundance. If there is any one inclined to be of opinion, with Timæus, that the waters of the river may be drawn out of the earth by the heat, it will be as well for him to bear in mind the fact, that the absence of shadow is a phænomenon which lasts continuously[17] in these regions.

The Nile begins to increase at the next new moon after the summer solstice, and rises slowly and gradually as the sun passes through the sign of Cancer; it is at its greatest height while the sun is passing through Leo, and it falls as slowly and gradually as it arose while he is passing through the sign of Virgo. It has totally subsided between its banks, as we learn from Herodotus, on the hundredth day, when the sun has entered Libra. While it is rising it has been pronounced criminal for kings or prefects even to sail upon its waters. The measure of its increase is ascertained by means of wells[18]. Its most desirable height is sixteen cubits[19]; if the waters do not attain that height, the overflow is not universal; but if they exceed that measure, by their slowness in receding they tend to retard the process of cultivation. In the latter case the time for sowing is lost, in consequence of the moisture of the soil; in the former, the ground is so parched that the seed-time comes to no purpose. The country has reason to make careful note of either extreme. When the water rises to only twelve cubits, it experiences the horrors of famine; when it attains thirteen, hunger is still the result; a rise of fourteen cubits is productive of gladness; a rise of fifteen sets all anxieties at rest; while an increase of sixteen is productive of unbounded transports of joy. The greatest increase known, up to the present time, is that of eighteen cubits, which took place in the time of the Emperor Claudius; the smallest rise was that of five, in the year of the battle of Pharsalia[20], the river by this prodigy testifying its horror, as it were, at the murder of Pompeius Magnus. When the waters have reached their greatest height, the people open the embankments and admit them to the lands. As each district is left by the waters, the business of sowing commences. This is the only river in existence that emits no vapours[21].

The Nile first enters the Egyptian territory at Syene[22], on the frontiers of Æthiopia; that is the name of a peninsula a mile in circumference, upon which Castra[23] is situate, on the side of Arabia. Opposite to it are the four islands of Philæ[24], at a distance of 600 miles from the place where the Nile divides into two channels; at which spot, as we have already stated, the Delta, as it is called, begins. This, at least, is the distance, according to Artemidorus, who also informs us that there were in it 250 towns; Juba says, however, that the distance between these places is 400 miles. Aristocreon says that the distance from Elephantis to the sea is 750 miles; Elephantis[25] being an inhabited island four miles below the last Cataract, sixteen[26] beyond Syene, 585 from Alexandria, and the extreme limit of the navigation of Egypt. To such an extent as this have the above-named authors[27] been mistaken! This island is the place of rendezvous for the vessels of the Æthiopians: they are made to fold up[28], and the people carry them on their shoulders whenever they come to the Cataracts.