Page:Africa by Élisée Reclus, Volume 4.djvu/387

 FIX)RA OF U8AGABA. 809 between the respective marine currcntfl. A stream of cold water Het« eteodily in the direction from south to north along the Atlantic seaboard, while a flood of tepid water, escaping from the greut central basin of the Indian Ocean, bathes the eastern shores of the contlueut, flowing southwards through the Mozambique ChanneL The hilly plateaux lying to the leeward of the Usagara highlands are mainly an arid region like the Karroos of Cape Colony. In many districts there is almost a total absence of water, so that the natives are obliged to sink deep wells in the grai'cl in order to collect the little moisture that oozes through the subsoil. In these districts the vuli season passes without bringing any regular heavy rains, while the massika is occasionally interrupted by a period of dry winds, sure forerunner of famine. The same atmospheric currents that bring the rain- charged clouds to the maritime slopes often deprive the plateau of the necessary moisture. To the dryness of the air are added the sultrj' heat of the day and cool nights. Whirlwinds of dust are often developed on the elevated plains, sweeping furiously over the land, and in their eddies bearing along coarse sund and at times even the shingle itself. What the Spaniards say of the Philippines, Burton applies to the Ugogo country : St'is vwzes de polvo, ncis mezes de lodo. which at night precipitate a copious dew, do not penetrate fur into the elevated lauds of the interior.* Flora and Fauna. The wealth of vegetation is regulated by the quantity of the rainfall. The zone of coastlands, being sufficiently watered, is everywhere clothed with her- baceous or forest growths. North of the Rovuma the terraced lands inhabited by the JJakondes present the same general aspect as the region south of that river, where the Mavihas have their camping-grounds. Here scrub and brushwood are matted into such dense masses, that no progress can be made except axe in band. In various parts of the northern section of the coastlands the vegetation, while equally dense and more leafy, has a more forest-like character. On leaving the villages, convoys at once plunge into arboreal avenues where the porters have great difficulty in forcing a passage through the tangled branches. Elsewhere the trees are rarer and often grouped in picturesque clusters. In the vicinity of the marshy tracts the reeds and tall grasses grow to a height of 12 or 14 feet, forming a dense jungle, where marauders at times lie in ambush to fall on the unwary wayfarer, or where runaway slaves find a temporary shelter. The msandaruHi^ or copal- tree, which yields the best gum known to commerce, flourishes along the banks of the Lower Rufiji for 35 or 40 miles from the coast. The highlands are clothed especially with mimosas and other plants of low for July (coldest month), IT ; number of rainj days, 120 ; total rainfall, 60 inches ; rainfall in 1859, 170 inches.
 * ' Six months of dust, six of bog." The vapour-charged fogs of the coastlands, '
 * Mean Cemperature of Zanzibar as recorded for four jeara, 82° F. ; for March (hottest month), W ;