The Ziwa, which lies 3,100 feet above the sea, occupies the lowest western level of Marenga Mk’háli, and is the deepest of the many inundated grounds lying to its north, north-east, and north-west. The extent greatly varies: in September, 1857, it was a slaty sheet of water, with granite projections on one side, and about 300 yards in diameter; the centre only could not be forded. The bottom and the banks were of retentive clay: a clear ring, whence the waters had subsided, margined the pool, and beyond it lay a thick thorny jungle. In early December, 1858, nothing remained but a surface of dry, crumbling, and deeply-cracked mud, and, according to travellers, it had long, in consequence of the scanty rains, been in that state. Caravans always encamp at the Ziwa when they find water there. The country around is full of large game, especially elephants, giraffes, and zebras, who come to drink at night; a few widgeon are seen breasting the little waves; “kata” (sand-grouse), of peculiarly large size and dark plumage, flock there with loud cries; and at eventide the pool is visited by guinea-fowl, floriken, curlews, peewits, wild pigeons, doves, and hosts of small birds. When the Ziwa is desiccated, travellers usually encamp in a thick bush, near a scanty clearing, about one mile to the north-west, where a few scattered villages of Wagogo have found dirty white water, hard and bad, in pits varying from twenty to thirty feet in depth. Here, as elsewhere in eastern Africa, the only trough is a small ring sunk in the retentive clayey soil, and surrounded by a little raised dam of mud and loose stones. A demand is always made for according permission to draw water--a venerable custom, dating from the days of Moses. “Ye shall buy meat of them (the Edomites) for money, that ye may eat; and ye shall also buy water of them for money, that ye may drink.”--Deut. ii. 6. Yet as thirsty, like hungry men, are not to be trifled with, fatal collisions have resulted from this inhospitable practice. Some years ago a large caravan of Wanyamwezi was annihilated in consequence of a quarrel about water, and lately several deaths occurred in a caravan led by an Arab merchant, Sallum bin Hamid, because the wells were visited before the rate of payment was settled. In several places we were followed upon the march lest a gourd might be furtively filled. To prevent exhaustion the people throw euphorbia, asclepias, and solanaceous plants into the well after a certain hour, and when not wanted it is bushed over, to keep off animals, and to check evaporation.