Mary Somerville (1780-1872) would have been a remarkable woman in any age, but as an acknowledged leading mathematician and astronomer at a time when the education of most women was extremely restricted, her achievement was extraordinary. Laplace famously told her that 'There have been only three women who have understood me. These are yourself, Mrs Somerville, Caroline Herschel and a Mrs Greig of whom I know nothing.' Mary Somerville was in fact Mrs Greig. After (as she herself said) translating Laplace's work 'from algebra into common language', she wrote On the Connexion of the Physical Sciences (1834), also reissued in this series. Her next book, the two-volume Physical Geography (1848), was a synthesis of geography, geology, botany, astronomy and zoology, drawing on the most recent discoveries in all these fields to present an overview of current understanding of the natural world and the Earth's place in the universe.