4th.--Early in the morning I took a walk of three miles easterly along the shore of the lake, and, ascending a small hill (which, to distinguish it, I have called Observatory Hill), took compass bearings of all the principal features of the lake. Mansur and a native, the greatest traveller of the place, kindly accompanied me, and gave me every obtainable information. This man had traversed the island, as he called it, of Ukéréwé from north to south. But by his rough mode of describing it, I am rather inclined to think that instead of its being an actual island, it is a connected tongue of land, stretching southwards from a promontory lying at right angles to the eastern shore of the lake, which, being a wash, affords a passage to the mainland during the fine season, but during the wet becomes submerged, and thus makes Ukéréwé temporarily an island. If this conjecture be true, Mzita must be similarly circumstanced. Cattle, he says, can cross over from the mainland at all seasons of the year, by swimming from one elevation of the promontory to another; but the Warudi, who live upon the eastern shore of the lake, and bring their ivory for sale to Ukéréwé, usually employ boats for the transit. A sultan called Machunda lives at the southern extremity of the Ukéréwé, and has dealings in ivory with all the Arabs who go there. One Arab at this time was stopping there, and had sent his men coasting along this said promontory to deal with the natives on the mainland, as he could not obtain enough ivory on the island itself. Considering how near the eastern shore of the lake is to Zanzibar, it appears surprising that it can pay men to carry ivory all the way round by Unyanyembé. But the Masai, and especially those tribes who live near to the lake, are so hostile to travellers, that the risk of going there is considered too great to be profitable, though all Arabs concur in stating that a surprising quantity of ivory is to be obtained there at a very cheap rate.