He was known as "Chally" or "Spirit" to the tribesmen of the Gabon and interior regions of equatorial Africa and as "Friend Paul" to thousands of juvenile readers. The world knew Paul Belloni Du Chaillu as a charming man with an incessant taste for exploring who was a gifted storyteller. He achieved great fame by becoming the first white man to see and shoot a gorilla and bring specimens of the animal to Europe for scientists to study. Like his contemporaries Heinrich Barth, Richard Francis Burton, John Hanning Speke, David Livingstone, and Henry M. Stanley, Du Chaillu made a career of traveling and writing. He spent the first half of his life defying jungle fevers, wild-animal attacks, and occasional hostile tribes as he rode the imperialist wave into equatorial Africa. After two trips to Africa and seven books on his explorations there, he turned to the chillier Scandinavian...