The author surveys the discovery and mapping of a major Central African river system, tracing its cataracts, channels, and the reach of navigable waterways into the interior. He outlines physical geography, vegetation, and climate while portraying household customs, social organization, and native religious ideas, including charms, secret societies, and instances of cannibalism. He chronicles missionary endeavours along the river, stations, language work, printed gospels, and the emergence of indigenous Christian congregations, and notes the growth of commerce, steamer traffic, and railway surveys driven by the ivory trade. He also describes recent political and boundary developments that have affected access, security, and the prospects for further exploration and settlement.