. He sought for a natural depression, and found one in the Libyan
range of hills to the west of the Nile valley, about a degree south of
the latitude of Memphis--a depression of great depth and of ample
expanse, fifty miles or more in length by thirty in breadth, and
containing an area of six or seven hundred square miles. It was
separated from the Nile valley by a narrow ridge of hills about two
hundred feet high, through which ran from south-east to north-west a
narrow rocky gorge, giving access to the depression. It is possible that
in very high floods some of the water of the inundation passed naturally
into the basin through this gorge; but whether this were so or no, it
was plain that by the employment of no very large amount of labour a
canal or cutting might be carried along the gorge, and the Nile water
given free access into the depression, not only in very high floods, but
annually when the inundation reached a certain moderate height. This is,
accordingly, what Amenemhat did. He dug a canal from the western branch
of the Nile--the modern Bahr Yousuf--leaving it at El-Lahoun, carried
his canal through the gorge, in places cutting deep into its rocky
bottom, and by a system of sluices and flood-gates retained such an
absolute control over the water that he could either admit or exclude
the inundation at his will, as it rose; and when it fell, could either
allow the water that had flowed in to return, or imprison it and keep it
back. Within the gorge he had thus at all times a copious store of the
invaluable fluid, banked up to the height of high Nile, and capable of
being applied to purposes of cultivation both within and without the
depression by the opening and shutting of the sluices.

So much appears to be certain. The exact size and position of
Amenemhat's reservoir within the depression, which a French _savant_ was
supposed to have discovered, are now called in question, and must be
admitted to be still _sub judice_. M. Linant de Bellefonds regarded the
reservoir as occupying the south-eastern or upper portion of the
depression only, as extending from north to south a distance of fourteen
miles only, and from east to west a distance varying from six to eleven
miles. He regarded it as artificially confined towards the west and
north by two long lines of embankment, which he considered that he had
traced, and gave the area of the lake as four hundred and five millions
of square metres, or about four hundred