For the information of such readers as may not have the original at hand, I append the following from Cary’s translation of Herodotus:  II.28

Jul 2001 The History of Herodotus V1 by Herodotus/ Macaulay [1hofhxxx.xxx]2707

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  With respect to the sources of the Nile, no man of all the
  Egyptians, Libyans, or Grecians, with whom I have conversed,
  ever pretended to know anything, except the registrar* of Minerva’s

<*the secretary of the treasury of the goddess Neith, or Athena as Herodotus calls her:  ho grammatiste:s to:n hiro:n xre:mato:n te:s Athe:naie:s>

treasury at Sais, in Egypt.  He, indeed, seemed to be trifling with me when he said he knew perfectly well; yet his account was as follows:  “That there are two mountains, rising into a sharp peak, situated between the city of Syene, in Thebais, and Elephantine.  The names of these mountains are the one Crophi, the other Mophi; that the sources of the Nile, which are bottomless, flow from between these mountains and that half of the water flows over Egypt and to the north, the other half over Ethiopia and the south.  That the fountains of the Nile are bottomless, he said, Psammitichus, king of Egypt, proved by experiment:  for, having caused a line to be twisted many thousand fathoms in length, he let it down, but could not find a bottom.”  Such, then, was the opinion the registrar gave, if, indeed, he spoke the real truth; proving, in my opinion, that there are strong whirlpools and an eddy here, so that the water beating against the rocks, a sounding-line, when let down, cannot reach the bottom.  I was unable to learn anything more from any one else.  But thus much I learnt by carrying my researches as far as possible, having gone and made my own observations as far as Elephantine, and beyond that obtaining information from hearsay.  As one ascends the river, above the city of Elephantine, the country is steep; here, therefore; it is necessary to attach a rope on both sides of a boat, as one does with an ox in a plough, and so proceed; but if the rope should happen to break, the boat is carried away by the force of the stream.  This kind of country lasts for a four-days’ passage, and the Nile here winds as much as the Maeander.  There are twelve schoeni, which it is necessary to sail through in this manner; and after that you will come to a level plain, where the Nile flows round an island; its name is Tachompso.  Ethiopians inhabit the country immediately above Elephantine, and one half of the island; the other half is inhabited by Egyptians.  Near to this island lies a vast lake, on the borders of which Ethiopian nomades dwell.  After sailing through this lake you will come to the channel of the Nile, which flows into it:  then you will have to land and travel forty days by the side of the river, for sharp rocks rise in the Nile, and there are many sunken ones, through which it is not possible to navigate a boat.