8 CHARACTER OF RIVERS . [chap. i. 
lias given it the well-known name of Balir el Azrak, or 
Blue River. No water is more delicious than that of 
the Blue Nile; in great contrast to that of the White 
river, which is never clear, and has a disagreeable taste 
of vegetation. This difference in the quality of the 
waters is a distinguishing characteristic of the two 
rivers : the one, the Blue Nile, is a rapid mountain 
stream, rising and falling with great rapidity; the 
other is of lake origin, flowing through vast marshes. 
The course of the Blue Nile is through fertile soil; 
thus there is a trifling loss by absorption, and during 
the heavy rains a vast amount of earthy matter of a 
red colour is contributed by its waters to the general 
fertilizing deposit of the Nile in Lower Egypt. 
The Atbara, although so important a river in the 
rainy season of Abyssinia, is perfectly dry for several 
months during the year, and at the time I first saw it, 
June 13, 1861, it was a mere sheet of glaring sand; 
in fact a portion of the desert through which it flowed. 
For upwards of one hundred and fifty miles from its 
junction with the Nile, it is perfectly dry from the 
beginning of March to June. At intervals of a few 
miles there are pools or ponds of water left in the deep 
holes below the general average of the river’s bed. In 
these pools, some of which may be a mile in length, 
are congregated all the inhabitants of the river, who as 
