The assertions of the missionaries were variously received. M. Vaux was thereby enabled to explain a statement in the Metereologica of Aristotle, where the first or main stream of the Nile is supposed to flow out of the mountain called Silver. Dr Beke accepted the meridional snowy range, and here placed his Mountains of the Moon, a hypothesis first advanced in 1846. The sceptics were headed by Mr W. D. Cooley, who in 1854 had published his ‘Claudius Ptolemy and the Nile.’ He had identified the mountain of Selene (σελήνη) with the snowy highland of ‘Semenai’ or ‘Samien’ in northern Abyssinia, and thus by adopting a mere verbal resemblance he had obtained a system of truly ‘lunatic mountains.’ Some years before (Journal Royal Geographical Society, vol. xv. 1845) appeared his paper entitled, ‘The Geography of N’yassi, or the great lake of Southern Africa investigated,’ a complicated misnomer. The article was written in a clear style and a critical tone, showing ample reading but lacking a solid foundation of fact. It began as usual with Pigafetta and de Barros, and it ended with Gamitto and Monteiro; the peroration, headed ‘Harmony of Authorities,’ was a self-gratulation, a song of triumph concerning the greatness of hypothetical discoveries, which were soon proved to be purely fanciful. Not one man in a million has the instincts of a good comparative geographer, and the author was assuredly not that exceptional man. His monograph did good by awaking the scientific mind, but it greatly injured popular geography. It unhappily asserted (p. 15) that ‘in every part of eastern Africa to which our inquiries have extended, snow is quite unknown.’ And the author having laid down his law bowed before it, and expected Fact as well as the Public to do the same; he even attacked the text of Ptolemy, asserting that the passages treating of the Nile sources and the Lunar Mountains were an interpolation of a comparatively recent date. In June and November 1863 the late Baron von der Decken, accompanied by Dr Kersten, an accomplished astronomical observer, ascended some 1300 feet, saw a clearly defined limit of perpetual snow at about 17,000 feet, and by a rough triangulation gave the main peak of Kilima-njaro an elevation of 20,065 feet. Still Mr Cooley, with singular want of candour, denied existence to the snow. It was the same with his ‘Single Sea,’ which under the meaningless and erroneous name ‘N’yassi’ again supplanted Ptolemy’s Lakes, and this want of acumen offered the last insult to African geography. Thus was revived the day when the Arab and Portuguese geographers made the three Niles (of Egypt, Magadoxo, and Nigritia) issue from one vast reservoir, and thus were the school maps of the world disfigured during half a generation. The lake also was painfully distorted, simply that it might ‘run parallel to the line of volcanic action drawn through the Isle de Bourbon, the north of Madagascar, and