The mountains are well supplied with water, which tastes sweet after the brackish produce of the maritime valley, and good when not rendered soft and slimy by lying long on rushy beds. Upon the middle inclines the burns and runnels of the upper heights form terraces of considerable extent, and of a picturesque aspect. The wide and open sole, filled with the whitest and cleanest sand, and retaining pools of fresh clear water, or shallow wells, is edged by low steep ledges of a dull red clay, lined with glorious patriarchs of the forest, and often in the bed is a thickly wooded branch or shoal-islet, at whose upper extremity heavy driftwood, arrested by the gnarled mimosa-clumps, and the wall of shrubs, attests the violence of the rufous-tinted bore of waves with which a few showers fill the broadest courses. Lower down the channels which convey to the plains the surplus drainage of the mountains are heaps and sheets of granite, with long reaches of rough gravel; their stony walls, overrun with vegetation, tower high on either hand, and the excess of inclination produces after heavy rains torrents like avalanches, which cut their way deep into the lower plains. During the dry season, water is drawn from pits sunk from a few inches to 20 feet in the re-entering angles of the beds. Fed by the percolations of the soil, they unite the purity of springs with the abundance of rain-supplies,--a comfort fully appreciated by down-caravans after the frequent tirikeza, or droughty afternoon-marches in the western regions. The versant of the mountains varies. In the seaward and the central sections streams flow eastward, and swell the Kingani and other rivers. The southern hills discharge their waters south and south-west through the Maroro River, and various smaller tributaries, into the “Rwaha,” which is the proper name for the upper course of the Rufiji. In the lateral plains between the ridges, and in the hill-girt basins, stagnant pools, which even during the Masika, or rainy season, inundate, but will not flow, repose upon beds of porous black earth, and engendering, by their profuse herbage of reeds and rush-like grass, with the luxuriant crops produced by artificial irrigation, a malarious atmosphere, cause a degradation in the people.