THE TANA EIVER. 851 Two other largo rivers of this region have their gourccs in the upland valloys of mountains in the western parts of the plateau. The Sabaki, or "Forest River," receives one of its affluents, the Tsavo, from the slopes of Kilima-Njaro, whereaa its chief headstreams take their rise in the Kiidu and Ulu ranges, and farther north in the chain skirting the plateau near Lake Naivasha. The Tana (Dana), the whole of whose middle course is still unexplored, has also its origin in the same border range, whence it bere takes the name of Kilama-nsi, or " River of the Mountain." Rut the Tana dcjes not become a considerable stream till it penetrates south of Mount Kenia, from the southern flanks of which it receives the contributions of numerous torrents. North of this region flow some other copious rivers, one of which, the Ururu, that is to say, " Thunder," has been so named from a tremendous cascade visited by Thomson, and by him described as plunging down several hundred feet without a break into a fearful gloomy gorge. The Ururu and the other streams which flow to the north-west and north of Mount Kenia, converge in a single channel to form the Gwaso n'Erok, or *' Black River," but east of Kenia the farther course of this river is still unexplored, and it is uncertain whether it continues to flow eastwards in the direction of the Juba, or bends round to the south-east to form a junction with the Tana. At Massa, the highest point of the valley where it was observed by the brothers Denhardt, the Tana is a stream averaging about IGO feet in breadth, with a rapid current exceeding three and a half miles an hour. Its depth varies from 12 to over 30 feet, and it is obstructed only by a small number of sandbanks covered by at least 3 feet of water. Like most other rivers in this part of the continent, the Tana receives no affluents along its lower course. On the contrary, it here overflows its banks to the right and left during its two annual floods, forming temporary morasses and lagoons, which spread out beyond the horizon on the low-lying plains. The riverain populations have raised along the river low embankments scarcely more than three fept high, which are pierced at intervals by irrigating rills ramifying amid the surrounding ricefields. When the waters subside in the mainstream, the overflow retires from the lagoons through these channels back to the Tana. Some of these channels, gradually deepened by the current, become navigable streams, com- municating from opening to opening along the meandcrings of the Tana, which itself occasionally shifts its bed and flows bodily into one or other of the lateral streams. As it approaches the coast the Tana bifurcates, the Mto Tana, or chief branch flowing southwards to Ungana Ray, the Bahia Formosa of the Portuguese, while the other, merely a shallow passage, merges eastwards in the estuary of the Ozi, that is, the " Black River " of the Gallas. The Belezoni, or Belondsoni, as this eastern branch is called, would soon be obstructed by the reeds, were it not kept open by the riverain people, who are able to navigate it with their light craft. In some places it is scarcely more than three feet from bank to bank, and is crossed at a bound by the natives. Nevertheless the Belezoni might easily be transformed to a broad navigable channel, by simply dredging and cutting through the soft alluvial soil of the surrounding plain.
