 He discovered one source of the Nile, the Semliki River, and became the first non-African to ever climb in the Ruwenzoris, reaching 10,677 ft before having to turn around.He was seriously wounded in the chest by a poisonous arrow during an attack by natives, many of whom assumed they were a slave-raiding party, and the expedition killed hundreds in return.Stairs recovered from his wound to continue the journey.