Having learned geology from Buch in addition to discovering new plant species, Smith was approached by the
Royal Society of London and asked to participate in a scientific expedition under Captain
James Hingston Tuckey to determine whether the
Congo River had any connection to the Niger basins of western and central Africa. Smith was to function as the expedition's
botanist and
geologist. He had as assistant
David Lockhart, who was to survive the journey. The Congo expedition began in February 1816 and went badly from the start. The original plan was to sail up the river using the expedition ship "", which had originally been constructed as a
steamboat, a technology that was still in its infancy. While the ship was eventually rigged for conventional sails, the heavy construction made it sit deep in the water. The accompanying lighter vessel "
Dorothy" was also used but was stopped by rapids 160 km inland. The expedition continued on foot up along the Congo through mosquito-infested swamps. The expedition advanced 450 kilometres up the river, but lack of food, hostile natives and ravaging tropical fevers forced the expedition to turn back without having found the sought connection. On the way downriver, Smith caught a tropical fever (probably
yellow fever) and died, less than a month shy of his 31st birthday. In all, 18 of the 56 members of the expedition perished, including all the scientists and the captain, who died after returning to the ship. The ill-fated expedition was part of the inspiration for
Joseph Conrad's
Heart of Darkness, written almost a century later. ==Smith's legacy==