[56] With reference to the object of this paper.
[57] Reisen, Bd. ii., 545.
[58] “Über den Stromlauf und das zunächst liegende Uferland des Nils, von der zweiten Katarakte bis Assuan, besitzen wir eine vortreffliche Karte namlich:” “Land zwischen der kleinen und grossen Katarakten des Nil. Astronomisch bestimmt und aufgenommen in J. 1827, durch v. Prokesch. Nil Grundrisse der Monumente. Wien, 1831.”—Reisen Bd. ii., Thl. iii. 86.
[59] Russegger, Reisen, Bd. i., 258.
[60] Travels in Ethiopia, p. 272.
Of the Breadth, Depth, and Velocity of the Nile, in Nubia.
Our information is very scanty respecting the breadth and depth of the river, either at the time of lowest water or during the inundations. About two miles above Philæ, it is stated by Jomard[61] to be 3000 metres, or nearly two English miles wide. At the second cataract, or rapid of Wadi-Halfa, it spreads over a rocky bed of nearly two miles and a-quarter in width (2000 klafter),[62] but contracts above the rapid to a third of a mile. Russegger also states, that the Nile, near Boulak, in Lower Egypt, is 2000 toises, nearly two-and-a-half English miles in breadth, and yet that it is considerably wider in some parts of Southern Nubia; but Burckhardt says, that the bed of the Nile in Nubia is, in general, much narrower than in any part of Egypt. Near Kalabsche, about 30 miles above Philæ, the river runs through a gorge not more than 300 paces wide, and its bed is full of granite blocks. It shortly afterwards again widens for some distance; but near Sialla, 78 miles above Philæ, it is contracted by the sandstone hills on both sides coming so near each other, that the river's bed is again not more than from 250 to 300 paces wide. It is about 600 yards broad about two miles above the second cataract near Wadi-Halfa, but is again very much contracted in the rocky region of Batn-el-Hadjar. At Aulike it is only 200 paces broad.[63]
I have not met with any measurements of the depth of the river in any part of its course in Nubia; but Hoskins describes it as being so shallow at the island of Sais, 327 miles above Philæ, on the 9th of June, which would be before the commencement of the inundation, as only to reach the knees of the camels.[64] Near Derr, about 86 miles below the Cataract of Wadi-Halfa, Norden, in January, found the river so shallow that loaded camels waded through it, and his boat frequently struck the ground. In May, Burckhardt found the river fordable at Kostamne, 53 miles above Philæ; and Parthey states, that between Philæ and the island of Bageh, to the west of it, the river is so shallow before the commencement of the inundation, that it may be waded through.[65] Burckhardt says, that from March to June the Nile-water, in Nubia, is quite limpid.[66] Miss Martineau, who visited Nubia in December and January, speaking of the river above Philæ says, that it “was divided into streamlets and ponds by the black islets. Where it was overshadowed it was dark-gray or deep blue, but when the light caught it rushing between a wooded island and the shore, it was of the clearest green.”[67] At the second cataract she describes the river as “dashing and driving among its thousand islets, and then gathering its thousand currents into one, proceeds calmly in its course.”[68]
Although we have no accurate measurements of the velocity of the Nile in Nubia, we may arrive at an approximate estimate of it by comparing its fall with that of a river well known to us.
I have stated the fall of the Nile in different parts of its course to be 5·30, 9·00, 12·00, and 13·12 inches in a mile. The fall of the Thames from Wallingford to Teddington Lock, where the influence of the tide ends, is as follows:—