John Leonard Riddell was a medical doctor, geologist, and botanist who traveled from New Orleans through Texas in 1839, surveying the Texas Hill Country for a group of businessmen searching for the lost San Saba silver mine. By joining the expedition, which of course did not find the mine, Riddell became the first trained scientist--preceding even Ferdinand Roemer--to visit the area of the Edwards Plateau and to provide a detailed description of the botany and geology along his route. James O. Breeden has here annotated the lively diary Riddell kept on his Hill Country trip and an article on Texas geology he later wrote. With notes and a substantial introduction, Breeden presents the scientist--his vitality, his accomplishments, and his role in the intellectual and civic life of his time--as well as the detailed story of his travels through Texas, adding considerably to our knowledge of the land as it was then