NILE, the great river of Egypt, is formed by the Bahr-nl-Abiad or White River, and Bahr-ul Azrak or Blue River, and flowing northwards, it disembogues into the Mediterranean Sea. In 1846, the brothers Abbadie believed they had discovered its sources south of Abyssinia, in lat. 49' N., and long. 34° 38' E., but subsequent travellers have shown that the brothers had given this title to the Uma, one of its affluents ; that the true sources were greatly farther south, and the great Lake Ukereve or Nyanza, which Captains Speke and Grant explored in 1862, is undoubtedly one source of the supply of the Nile waters. The Nile traverses Nubia, fertilizing Halfay, Chendy, Darner (where it receives on its right bank the Takazza or Athara), Chakye, Dongola, Mahas, Sukhot, Hajar, and Barabras. It enters Egypt at Assouan, in lat. 24° N., and runs almost directly from S. to N. to lat. 30° 12' N., where it divides into two branches, that of Rosetta on the west near Alexandria, and that of Damietta on the east, and both of which have seven distinct mouths. It has six cataracts in its course, but the only one of consequence is that of the ancient Philoe, the modern El-Birhe near Assouan, at the boundary of Egypt and Nubia. About the summer solstice the rise of the Nile is observed to em inence above the last cataract. This rise becomes apparent at Cairo in the first days of July, and its progressive increase there is indicated by the Nilometer, which has been established at the extremity of the isle of Roda. For the first six or eight days its rise is almost insensible. Soon, however, its daily increase becomes more rapid. Towards the 15th August it has attained to half its highest rise, which it usually attains about the 20th or 30th September. When it has reached this stage, it remains nearly statioliary for about 15 days, after which it begins to fall, but much more gently than it rose. By the 10th November it has fallen to half the height to which it had risen, and it continues to subside till the 20th of May of the following year, from which date there are no sensible changes until its rise recommences at the ordinary time of the year. The causes of its rise are now well known. During the hot months of the year, rain falls every day in Habbesh or Abyssinia, and all that rain-water is collected into the Nile, which, from its entrance into Egypt till it reaches the sea, runs through a wide vale.
It does not rise alike high through all Egypt. In Upper Egypt the rise is about 30 feet, and at the Nilometer on Roda Island, at Cairo, the full height is 21 feet above its ordinary level. At Rosetta and Damietta it is only four feet. At Cairo, the Nile being confined to one channel, between high banks, must necessarily rise to a much greater height than nearer the sea, where it is divided into two streams, after running over so much barren ground, and forming so many lakes. The branch upon which Rosetta stands is only 650 feet broad ; and that by Damietta, not more than 100. Between the dyke of the canal of Cairo and the Nile, a pillar of earth is raised, nearly of the height to which the waters of the rivers are expected to rise. This pillar is called Arils, or the bride, and serves as a sort of Nilometer, for the use of the common people. When the waters enter the canal, this bride is carried away by the current. A like custom, which prevailed among the ancient Egyptians, has subjected them to the imputation of sacrificing every year a virgin to the Nile. Nukta signifies, in Arabic, both a drop and the time of the sun's entering the sign of Cancer, at which season the great rains fall in Abyssinia, which occasion the swelling of the Nile. The rise of the Nile, as shown by the Rods Island Nilometer, is daily proclaimed in the streets of the metropolis, from its commencement, about the beginning of July (the Coptic month Baooneh), until it has attained the sixteenth cubit of the Nilometer. The Wifa-un-Nil (the completion or abundance of the Nile) is then proclaimed, gen erally between the 6th and 16th of August (or 1st and 11th of the Coptic month Mesra). On the day following, the Nile is admitted into the canal which traverses the city, and thereafter only the increase of the river above 16 cubits is notified. On the date the river reaches its greatest height, usually on the last days of September, the public cry of the river's state ceases, and the shaikh of the Nilometer becomes entitled to a fee from the Government for every digit of the river's increase.