The irrigation system of Egypt is but little changed since the olden time.  Some new canals have been cut, and yet more have been silted up through the negligence of those in power; but the general scheme, and the methods employed, continue much the same, and demand but little engineering skill.  Wherever I have investigated the remains of ancient canals, I have been unable to detect any traces of masonry at the weak points, or at the mouths, of these cuttings.  They are mere excavated ditches, from twenty to sixty or seventy feet in width.  The earth flung out during the work was thrown to right and left, forming irregular embankments from seven to fourteen feet in height.  The course of the ancient canals was generally straight:  but that rule was not strictly observed, and enormous curves were often described in order to avoid even slight irregularities of surface.  Dikes thrown up from the foot of the cliffs to the banks of the Nile divided the plain at intervals into a series of artificial basins, where the overflow formed back-waters at the time of inundation.  These dikes are generally earth-works, though they are sometimes constructed of baked brick, as in the province of Girgeh.  Very rarely are they built of hewn stone, like that great dike of Kosheish which was constructed by Mena in primaeval times, in order to divert the course of the Nile from the spot on which he founded Memphis.[7] The network of canals began near Silsilis and extended to the sea-board, without ever losing touch of the river, save at one spot near Beni Suef, where it throws out a branch in the direction of the Fayum.  Here, through a narrow and sinuous gorge, deepened probably by the hand of man, it passes the rocky barrier which divides that low-lying province from the valley of the Nile, and thence expands into a fanlike ramification of innumerable channels.  Having thus irrigated the district, the waters flow out again; those nearest the Nile returning by the same way that they flowed in, while the rest form a series of lakes, the largest of which is known as the Birket el Kurun.  If we are to believe Herodotus, the work was not so simply done.  A king, named Moeris, desired to create a reservoir in the Fayum which should neutralise the evil effects of insufficient or superabundant inundations.  This reservoir was named, after him, Lake Moeris.  If the supply fell below the average, then the stored waters were let loose, and Lower Egypt and the Western Delta were flooded to the needful height.  If next year the inundation came down in too great force, Lake Moeris received and stored the surplus till such time as the waters began to subside.  Two pyramids, each surmounted by a sitting colossus, one representing the king and the other his queen, were erected in the midst of the lake.  Such is the tale told by Herodotus, and it is a tale which has considerably embarrassed our modern engineers and topographers.  How, in fact, was it possible to find in the Fayum