The International Astronomical Union and the International Union for the History and Philosophy of Science have sponsored a major work on the history of astronomy, which the Press publishs are in four volumes, three of which will be divided into two parts. Publication commenced with volume 4, part A. The history of astronomy has never been tackled on this scale and depth and this major synthesis breaks wholly new ground. The individual chapters of each volume have been prepared by leading experts in every field of the history of astronomy.