Letters from Egypt, Ethiopia, and the peninsula of Sinai

part immediately below the second cataract, where the average fall is

only 5·30 inches for a distance of 96 miles, is quite evident.

The power of a river to abrade the soil over which it flows, so far as water is by itself capable of doing so, must depend upon its volume and velocity, and the degree of hardness of the material acted upon. The power is increased when the water ...