William Gascoigne (c.1612-44) was the inventor of the telescopic sight and micrometer (instruments crucial to the advance of astronomy). His name is now known to historians of science around the world. For some considerable time after his tragic death at the age of 32 in the English Civil War, however, it seemed as if his achievements would be consigned to oblivion. Most of his papers were lost and even the few that survived have largely disappeared. This is the story of how his work was rescued. Into this story is woven an account of the state of astronomy and optics during Gascoigne's lifetime, so that the reader can appreciate the significance of his discoveries.

David Sellers is a Fellow of the Royal Astronomical Society and a founder member of the Society for the History of Astronomy. Before retirement he was a Chartered Civil Engineer working in flood risk management. He is the author of The Transit of Venus: the Quest to Find the True Distance of the Sun (Leeds, 2001) and co-author of Vénus Devant le Soleil (Paris, 2003).

Part 1: The 'Discovery' of William Gascoigne.- Introduction.- The Gascoignes of Thorp-On-The-Hill.- The 'Discovery' of William Gascoigne.- A 'Light of the First Magnitude'.- Derham and de la Hire.- Bevis and de la Hire.- In His Own Hand.- Part 2: Gascoigne's World.- The Religious World of William Gascoigne.- The Optical World of William Gascoigne.- The Astronomical World of William Gascoigne.- Part 3: Digging Further.- The Flamsteed Transcriptions.- Bodleian Transcriptions.- British Library MSS and Other Transcriptions.- The Civil War and After.- The Road to Civil War.- After Marston Moor.- The Legacy of William Gascoigne.