From a desire of gaining a reputation for sagacity, this subject has employed the attention of many among the Greeks. There have been three different modes of explaining it, two of which merit no further attention than barely to be mentioned; one of them affirms the increase of the Nile to be owing to the Etesian winds, which by blowing in an opposite direction, impede the river’s entrance to the sea. But it has often happened that no winds have blown from this quarter, and the phenomenon of the Nile has still been the same. It may also be remarked, that were this the real cause, the same events would happen to other rivers, whose currents are opposed to the Etesian winds, which, indeed, as having a less body of waters, and a weaker current, would be capable of still less resistance: but there are many streams, both in Syria and Libya, none of which exhibit the same appearances with the Nile.
The second opinion is still less agreeable to reason, though more calculated to excite wonder. This affirms, that the Nile has these qualities, as flowing from the Ocean, which entirely surrounds the earth.
The third opinion, though more plausible in appearance, is still more false in reality. It simply intimates that the body of the Nile is formed from the dissolution of snow, which coming from Libya through the regions of Ethiopia, discharges itself upon Egypt. But how can this river, descending from a very warm to a much colder climate, be possibly composed of melted snow? There are many other reasons concurring to satisfy any person of good understanding, that this opinion is contrary to fact. The first and the strongest argument may be drawn from the winds, which are in these regions invariably hot: it may also be observed that rain and ice are here entirely unknown. Now if in five days after a fall of snow it must necessarily rain, which is indisputably the case, it follows that if there were snow in those countries, there would certainly be rain. The third proof is taken from the colour of the natives, who from excessive heat are universally black; moreover, the kites and the swallows are never known to migrate from this country: the cranes also, flying from the severity of a Scythian winter, pass that cold season here. If, therefore, it snowed although but little in those places through which the Nile passes, or in those where it takes its rise, reason demonstrates that none of the above-mentioned circumstances could possibly happen.
The argument which attributes to the ocean these phenomena of the Nile, seems rather to partake of fable than of truth or sense. For my own part, I know no river of the name of Oceanus; and am inclined to believe that Homer, or some other poet of former times, first invented and afterwards introduced it in his compositions.
But as I have mentioned the preceding opinions only to censure and confute them, I may be expected perhaps to give my own sentiments on this subject. It is my opinion that the Nile overflows in the summer season, because in the winter the sun, driven by the storms from his usual course, ascends into the higher regions of the air above Libya. My reason may be explained without difficulty; for it may be easily supposed, that to whatever region this power more nearly approaches, the rivers and streams of that country will be proportionably dried up and diminished.
If I were to go more at length into the argument, I should say that the whole is occasioned by the sun’s passage through the higher parts of Libya. For as the air is invariably serene, and the heat always tempered by cooling breezes, the sun acts there as it does in the summer season, when his place is in the centre of the heavens. The solar rays absorb the aqueous particles, which their influence forcibly elevates into the higher regions; here they are received, separated, and dispersed by the winds. And it may be observed, that the south and southwest, which are the most common winds in this quarter, are of all others most frequently attended with rain: it does not, however, appear to me that the sun remits all the water which he every year absorbs from the Nile; some is probably withheld. As winter disappears, he returns to the middle place of the heavens, and again by evaporation draws to him the waters of the rivers, all of which are then found considerably increased by the rains, and rising to their extreme heights. But in summer, from the want of rain, and from the attractive power of the sun, they are again reduced; but the Nile is differently circumstanced, it never has the benefit of rains, whilst it is constantly acted upon by the sun,—a sufficient reason why it should in the winter season be proportionably lower than in summer. In winter the Nile alone is diminished by the influence of the sun, which in summer attracts the water of the rivers indiscriminately; I impute, therefore, to the sun the remarkable properties of the Nile.
To the same cause is to be ascribed, as I suppose, the state of the air in that country, which from the effect of the sun is always extremely rarefied, so that in the higher parts of Libya there prevails an eternal summer. If it were possible to produce a change in the seasons, and to place the regions of the north in those of the south, and those of the south in the north, the sun, driven from his place by the storms of the north, would doubtless affect the higher parts of Europe, as it now does those of Libya. It would also, I imagine, then act upon the waters of the Ister, as it now does on those of the Nile.
That no breeze blows from the surface of the river, may, I think, be thus accounted for: Where the air is in a very warm and rarefied state, wind can hardly be expected, this generally rising in places which are cold. Upon this subject I shall attempt no further illustration, but leave it in the state in which it has so long remained.
A Water-carrier on the Nile