[Illustration:  245.jpg SCALE OF THE NILOMETER]

An analysis of the Nile alluvium, which has accumulated in the course of ages to a thickness of from three to four feet above the old river-bed, shows that it contains a considerable percentage of such fertilising substances as carbonate of lime and magnesia, silicates of aluminum, carbon, and several oxides.  Where the water has to be raised to higher levels, two processes are used.  The primitive shadoof of native origin figured on a monument as far back as 3,300 years ago, and the more modern sakieh was apparently introduced in later times from Syria and Persia.  The shadoof is used on small farms, and the sakieh is more often used for larger farms and plantations.  These contrivances line the whole course of the Nile from Lower Egypt to above Khartum.  The shadoof will raise six hundred gallons ten feet in an hour, and consists of a pole weighted at one end, with a bucket at the other; when the water is raised the weight counterbalances the weight of the full bucket.  The sakieh, which will raise twelve hundred gallons twenty or twenty-four feet in an hour, is a modified form of a Persian wheel, made to revolve by a beast of burden; it draws an endless series of buckets up from the water, and automatically empties them into a trough or other receptacle.  In former times these appliances were heavily taxed and made the instruments of oppression, but these abuses have been reformed since Egypt came under a more humane form of government.

Another interesting feature of the water ways of Egypt is the intermittent watercourses.  The largest of these is the Khor Baraka (Barka), which flows out towards Tapan, south of Suakin.  It presents some analogy to the Nile, and in part was undoubtedly a perennial stream 250 miles long, and draining seven or eight thousand square miles.  At present its flat sandy bed, winding between well-wooded banks, is dry for a great part of the year.  This route is extensively used for the caravan trade between Suakin and Kassala.  During September the water begins to flow, but is spasmodic.  After the first flood the natives plant their crops, but sometimes the second flow, being too great, cannot be confined to the limits prepared for it, and the crops are carried away and the sowing must of necessity be started again.

[Illustration:  247.jpg A MODERN SAKIEH]

The canals of Egypt are of great aid in extending the beneficial influence of the inundations of the Nile.  In Lower Egypt is the Mahmudiyeh Canal, connecting Alexandria with the Rosetta branch, and following the same direction as an ancient canal which preceded it.