The altitude of the most northerly point to which the Doctor traced the wonderful river was a little over two thousand feet, so that though Baker makes out his lake to be two thousand seven hundred feet above the sea, yet the Bahr Ghazal, through which Petherick’s branch of the White Nile issues into the Nile is only a little over two thousand feet, in which case there is a possibility that the Lualaba may be none other than Petherick’s branch. It is well known that trading stations for ivory have been established for about five hundred miles up Petherick’s branch. We must remember this fact when told that Gondokoro, in latitude four degrees north, is two thousand feet above the sea, and latitude four degrees south, where the Doctor was halted, is only a little over two thousand feet above the sea. That two rivers, said to be two thousand feet above the sea, separated from each other by eight degrees of latitude, are the same stream may, among some men, be regarded as a startling statement. But we must restrain mere expressions of surprise and take into consideration that this mighty and broad Lualaba is a lacustrine river--broader than the Mississippi--and think of our own rivers, which, though shallow, are exceedingly broad. We must wait also until the altitude of the two rivers--the Lualaba, where the Doctor halted, and the southern point on the Bahr Ghazal, where Petherick has been--are known with perfect accuracy. [Illustration: CHARACTERISTIC HEAD-DRESSES.] “Webb’s River, or the Lualaba, from Bangweolo is a lacustrine river, expanding from one to three miles in breadth. At intervals it forms extensive lakes, then contracting into a broad river it again forms a lake, and so on to latitude four degrees north, and beyond this point the Doctor heard of a large lake again north. Now, for the sake of argument, suppose we give this nameless lake a length of four degrees latitude, as it may be the one discovered by Piaggia, the Italian traveller, from which Petherick’s branch of the White Nile issues out through reeds, marshes and the Bahr Ghazal into the White Nile south of Gondokoro. By this method we can suppose the rivers one--for the lakes extending over so many degrees of latitude would obviate the necessity of explaining the differences of latitude that must naturally exist between the points of a river eight degrees of latitude apart. Also, that Livingstone’s instruments for observation and taking altitude may have been in error, and this is very likely to have been the case, subjected as they have been to rough handling during nearly six years of travel.