'Sidrophel the quack astrologer exposed, King Charles ye Martyr, vindicated, and judicial astrologie proved false, groundless, destructive of religion, and ye common peace, in a letter to Mr. W. Salmon.' There are eleven preliminary pages comprised of a dedication to Dr Sherlock, Dean of St Paul's, dated Plymouth, 23 October 1692, and a message 'To the reader'. These are followed by fifty numbered pages of text, in which Yonge attacks the medical empiric William Salmon (1644-1713). The manuscript was written by an amanuensis, but includes revisions in the author's hand and additions on inserted slips. It was prepared for a printer, and there is an autograph note by Yonge at the front giving detailed directions for its printing. Ultimately, the manuscript was not printed in this form. The additions to the text were probably made subsequent to the decision not to print, when it had become clear that the extent of the required revision would make it necessary to produce another fair copy for the print er. The volume is accompanied by a photocopy from the Sotheby's sale catalogue, 30 June 1972, describing its contents, and correspondence regarding the acquisition of the collection by Cambridge University Library.