Little is known about William Clarke, the author of this 1819 survey of libraries in Britain, though hints in the opening pages suggest that he was acquainted with the activities of the Roxburghe Club. His object is 'to assist ... the collector in his pursuit of valuable editions of rare books'. A short survey of the major libraries of Europe is followed by descriptions of the collections which make up the British Museum's library, the great 'public' libraries, including those of Oxford and Cambridge, and the libraries of learned societies. Private libraries covered include those of Sir Joseph Banks, William Beckford, and the duke of Marlborough. The final portion of the work describes the content of some great library sales (a fuller list of sales having been given earlier in the book), from the seventeenth century to Clarke's own time. This remains a useful source for bibliographers and those interested in the provenance of books.