source in Paradise,
to traverse burning regions inaccessible to man, and afterwards to fall
into a sea whence it made its way to Egypt. Sometimes it carried down
from its celestial sources branches and fruits unlike any to be found
on earth. The sea mentioned in all these tales is perhaps a less
extravagant invention than we are at first inclined to think. A lake,
nearly as large as the Victoria Nyanza, once covered the marshy plain
where the Bahr el-Abiad unites with the Sobat, and with the Bahr
el-Ghazal. Alluvial deposits have filled up all but its deepest
depression, which is known as Birket Nu; but, in ages preceding our era,
it must still have been vast enough to suggest to Egyptian soldiers and
boatmen the idea of an actual sea, opening into the Indian Ocean.
The mountains, whose outline was vaguely seen far to southward on the
further shores, doubtless contained within them its mysterious source.
There the inundation was made ready, and there it began upon a fixed
day. The celestial Nile had its periodic rise and fall, on which those
of the earthly Nile depended. Every year, towards the middle of June,
Isis, mourning for Osiris, let fall into it one of the tears which she
shed over her brother, and thereupon the river swelled and descended
upon earth. Isis has had no devotees for centuries, and her very name is
unknown to the descendants of her worshippers; but the tradition of her
fertilizing tears has survived her memory. Even to this day, every one
in Egypt, Mussulman or Christian, knows that a divine drop falls from
heaven during the night between the 17th and 18th of June, and forthwith
brings about the rise of the Nile. Swollen by the rains which fall
in February over the region of the Great Lakes, the White Nile rushes
northward, sweeping before it the stagnant sheets of water left by the
inundation of the previous year. On the left, the Bahr el-Ghazal brings
it the overflow of the ill-defined basin stretching between Darfur and
the Congo; and the Sobat pours in on the right a tribute from the rivers
which furrow the southern slopes of the Abyssinian mountains. The first
swell passes Khartum by the end of April, and raises the water-level
there by about a foot, then it slowly makes its way through Nubia, and
dies away in Egypt at the beginning of June. Its waters, infected
by half-putrid organic matter from the equatorial swamps, are not
completely freed from it even in the course of this long journey, but