In the month of August 1874, Lieutenant Cameron, whom we left at Ujiji after the delineation of that part of Lake Tanganika south of Ujiji, after traversing Livingstone’s route to Kasongo’s Manyema, and travelling by canoe about thirty-five miles, reaches Nyangwé, his predecessor’s farthest point. Though he does not attempt to resolve this problem, or penetrate the region north of Nyangwé, Lieutenant Cameron ventures upon the following hypothesis: “This great stream must be one of the head-waters of the Kongo, for where else could that giant amongst rivers, second only to the Amazon in its volume, obtain 2,000,000 cubic feet of water which it unceasingly pours each second into the Atlantic? The large affluents from the north would explain the comparatively small rise of the Kongo at the coast; for since its enormous basin extends to both sides of the equator, some portion of it is always under the zone of rains, and therefore the supply to the main stream is nearly the same at all times, instead of varying as is the case with tropical rivers, whose basins lie completely on one side of the equator.” Lieutenant Cameron illustrates his hypothesis by causing Livingstone’s great river to flow soon after leaving Nyangwé straight westward, the highest part of which is only 3° 30′ S. lat. At Nyangwé, Lieutenant Cameron crossed the river, proceeded south with some Arab traders a few days’ journey, then, accompanied by guides, travelled still south to Juma Merikani’s, or Kasongo’s, thence, after a stay of nearly nine months, accompanied by Portuguese traders, he proceeded to Benguella, a small port belonging to the Portuguese Government on the Atlantic Ocean, having crossed Africa from east to west south of S. lat. 4°. The above is a brief sketch which with the aid of the small maps attached to this volume explains and illustrates the several geographical problems left by my predecessors. I now propose to describe how these problems were solved, and the incomplete discoveries of Burton and Speke, Speke and Grant, and Doctor Livingstone were finished, and how we sighted the lake Muta N’zigé, by its broad arm, which I have called Beatrice Gulf, by a comprehensive exploration, lasting, from sea to sea, two years eight months and twenty days; the results of which are to be found embodied in these two volumes, entitled: ‘_Through the Dark Continent; the Sources of the Nile, around the Great Lakes of Africa, and down the “Livingstone” to the Atlantic Ocean_.’ ----- # 1: The portrait has been graciously subscribed— “All’ intrepido viaggiatore “Enrico Stanley “UMBERTO RE.” # 2: