Leonard Horner (1785-1864) was a prominent geologist, educator and, later, a factory inspector. In 1833 he was appointed to the Royal Commission on the employment of children in factories, and he inspected sites around the north of England. His earlier scientific work saw him elected a fellow of the Royal Society in 1813, and he was twice president of the Geological Society. The two-volume Memoir of Leonard Horner, edited by his daughter, Katharine Lyell, and published in 1890, is a selection of letters to and from his family and friends. The correspondence gives vivid insights into the world of this influential reformer. Volume 1 focuses on Horner’s life from his childhood until 1838, taking in many of the key events of his professional career, including his election to the Royal Society, his attempts at improving higher education in Edinburgh and his involvement with the inspection of factories.