"Slug Map" including Kilimanjaro

A map prepared for Johannes Rebmann by Jakob Erhardt.

From a bio of Rebmann:
"During their time in Africa, Krapf and Rebmann worked their way into the interior of the continent. They traveled to several areas in the regions of Central and Eastern Africa, including to what is now known as the African Great Lakes. The finding of one especially large lake (Uniamési) is depicted in a map known as the 'Slug' map. It was known by this name because the layout of the water body suggested a shape similar to that of a slug.

The basis for the map was prepared by the missionary Jakob Erhardt from the reports of his companions Krapf and Rebmann, and from verbal information that he had acquired from local people. Erhardt was struck by the fact that travelers who had gone inland from different points on the coast had all come to an inland sea. In November 1854, while talking about the problem to Rebmann, "at one and the same moment, the problem flashed on both of us solved by the simple supposition that where geographical hypothesis had hitherto supposed an enormous mountain-land, we must now look for an enormous valley and an inland sea." On the map that he and Rebmann drew, the three lakes of Victoria, Tanganyika and Nyasa are shown as one very large L-shaped lake.

On the map, several subtle but interesting things can be discovered, including, in the northeast section of the cartograph, a reference to a stream flowing into Lake Victoria, then known by the missionaries as "the Ukerewa". A note describes how the waters of the stream were very sweet, but stained the teeth a sickly yellow. This note is probably the first known text referring to the drinking water, found primarily around Mount Meru, which has a high content of fluorine and causes a yellow-brown stain to the incisors which cannot be removed."

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