The «slug map»: missionaries, cartography and cross-cultural information exchange in East Africa around 1850
Cartographica Helvetica 45 (2012) 27–38
Until the mid-19th century the maps of inner East Africa still contained large uncharted areas. It was not until the so-called «slug map» showing a gigantic inland lake in the heart of Africa appeared in Petermann's Geographischen Mittheilungen (PGM) in 1856, that fundamental changes began to find their way onto the maps of this region. The map was based on sketches by Jakob Erhardt and Johannes Rebmann, missionaries from Württemberg at the Church Missionary Society (CMS) of London. Their information, however, was based more on statements by indigenous people rather than on their own observations from expeditions. Therefore, Erhardt's map may be considered as the product of European-African information exchange, whose basic information stemming from indigenous witnesses, however, was filtered and altered in the process of visualization and European learning and knowledge. Starting with the description of data gathering and the participating actors in the field, this article shows how African knowledge was discussed and acquired in the course of surveying and mapping East Africa.