Used to describe both binary systems and optical doubles, the term 'double star' has been familiar to astronomers since the seventeenth century. This book, first published in 1879, outlines the history of their study, and describes the methods and equipment needed in order to observe the fascinating phenomenon. Written for non-specialists by Fellows of the Royal Society Edward Crossley (1841 1904), Joseph Gledhill (1837 1906) and James M. Wilson (1836 1931), the catalogue of over 1,200 double stars appears beside detailed notes and does not assume mathematical expertise. Also offered are a...