Franz Keller was a German engineer who spent 17 years in Brazil. In 1867, Keller and his father were commissioned by the minister of public works in Rio de Janeiro to explore the Madeira River in order to determine the feasibility of building a railroad to circumvent rapids that made steamship navigation impossible on part of the river. This book, published some seven years later, describes the river and its rapids, the native tribes that Keller and his party encountered, and the animals and vegetation of the virgin forest of the Amazon and the Madeira rivers. Keller’s expedition extended into eastern Bolivia. It devotes a chapter to the Mojo Indians of that region and the history of their interactions with the Jesuit missions dating from the late 17th century.