As early as 1830, astronomer John Herschel had already recognised the need for the genre of popular science. In a letter to philosopher William Whewell, he wrote that the general public needed "digests of what is actually known in each particular branch of science... to give a connected view of what has been done, and what remains to be accomplished." Indeed, as the British population became not just increasingly literate but also well-educated, there was growing demand for science titles. Mary Somerville became an early and highly successful science writer of the nineteenth century. Her "On the Connexion of the Physical Sciences" (1834), intended for the mass audience, sold quite well. Arguably one of the first books in the genre of popular science, it contained few diagrams and very little mathematics. It had ten editions and was translated to multiple languages. As its name suggests, it offered readers a broad overview of the physical sciences at a time when these studies were becoming increasingly distinct and specialised. It was the most popular science title from the publisher John Murray until Charles Darwin's "On the Origin of Species" (1859). Although Somerville's rendition of Pierre-Simon de Laplace's masterpiece "Mécanique Céleste", "The Mechanism of the Heavens" (1831), was intended to inform the masses of the latest advances in Newtonian mechanics and gravitation, it was also used as a textbook for students at the University of Cambridge till the 1880s.