feet, and here several streams traversing a gently rolling plateau converge in a single channel, known in its upper course as the Tchasi, and lower down as the Tchambesi. Its course is at first from north-east to south-west in the direction of the Zambese basin, from which it is separated only by a low parting-line, but farther down, after collecting several other streams and emissaries of extensive morasses, it enters Lake Bemba, or Bangweolo, southernmost of all the great sheets of water belonging to the Congo hydrographic system.
Bangweolo, discovered in 1868 by Livingstone, and revisited by him five years afterwards to end his days on its southern shores, is an extremely irregular lacustrine
basin divided into numerous secondary sections by islands and peninsulas. Its altitude, estimated by Livingstone at 3,700, is raised by Giraud to 4,300 feet, while the forests of reeds occupying a great part of the depression render it difficult to form a correct idea of its total area. The open water at the northern extremity develops a vast oval, stretching for 60 miles beyond the horizon towards the south-west. About the centre lies the island of Kissi, highest of the archipelago, rising 60 feet above the surrounding waters, which are nowhere more than 18 or 20 feet deep, and which towards the south-east are lost in a submerged plain, overgrown with sedge. Even the Tchambesi flows throughout its lower course amid low-lying marshy tracts overgrown with reeds, giving them an aspect son a boundless grassy plain relieved here and there by clumps of trees. Banks rising
