Sir John Herschel, one of the founders of Southern Hemisphere astronomy, was a man of extraordinarily wide interests. He made contributions to botany, geology, and ornithology, as well as to astronomy, chemistry, and mathematics. Throughout his scientific career he kept a diary, recording his public and private life. The diaries from 1834 to 1838, years he spent making astronomical observations at the Cape of Good Hope, are reproduced in this book and prove to be much more than an ordinary scientist’s logbook. They present personal and social history, literary commentaries, the results of close observations of nature and numerous scientific experiments, the excitement of travel, political intrigues, gossip, and philosophical reflections—all interpreted through an alert and versatile mind. In the present transcription, the material has been enriched with selected correspondence of Sir John and his wife Lady Herschel (née Margaret Brodie Stewart). Sir John devoted his working time at the Cape primarily to a systematic observation of the southern sky, complementing his earlier “sweeping” of the northern sky at Slough, England. He later became one of the founders of photography, but at the Cape he used a simple optical device, the camera lucida, in the production of numerous landscape drawings. Many of these, along with reproductions of sketches contained in the diaries and botanical drawings made by Sir John and Lady Herschel, are used to illustrate this book. Sir John was also a leading figure in the foundation of the educational system of the Cape and a supporter of exploratory expeditions into the interior. As the son of Sir William Herschel, in his day the most famous British astronomer and the discoverer of the planet Uranus, Sir John was already celebrated when he arrived from England. Every individual of note, resident at the Cape or visiting, went to see him. He was supported in his work by his wife, who ran an enormous establishment and bore a huge family, but who nevertheless found time to travel in the country around the western Cape with him and to assist in his observations. The diaries and letters are supplemented by especially valuable editorial notes that provide much needed and highly interesting information concerning persons and events mentioned and described by Sir John. All the original manuscript material used in this volume is archived at the Harry Ransom Center at the University of Texas at Austin. Sir John’s camera lucida drawings are from the South African Public Library in Cape Town.