In the nineteenth century people could gain fame and fortune by "discovering" and documenting things that were already known to exist like the source of the Nile and the North Pole. For decades trappers and prospectors had told about the wonders of the area that became Yellowstone Park, but no credible person had written about the falls, canyons, and geysers there. An ambitious politician, Nathaniel P. Langford, decided to make his name by promoting...