Sundials: An Illustrated History of Portable Dials fills a major gap i the published works on the subject. Most books previously printed have concentrated on notable fixed sundials or on the mathematics involved in their construction. This work focuses on the portable sundials used as timekeepers for three millenia before being superseded by the watch. While the emphasis is on the sundials themselves, much reference is made to the contemporary social, political and economic history, so that the subject matter is set firmly in context. In each chapter one or two detailed examples have been selected as a focus for the wider field; all are of particular interest in their own right. Most of the sundials come from the collections of the National Maritime Museum, and dials from all major manufacturing countries throughout the world are added. The illustrations form an essential part of the book, both as an aid to explaining how the dials work, and because many are functional works of art of extremely high visual quality. The detailed examples in each chapter are fully illustrated. Diagrams have also been provided to explain in easy terms some of the complicated mathematics involved in the construction and use of dials. Other illustrations complement the background of historical material.