At the beginning of this work it would not be right to omit an expression of the liveliest feelings of gratitude to two friends of long standing; the Rev. H. A. Wilson, of Magdalen College, and the Rev. Dr Kidd, Hon. Canon of Christ Church. To the latter I am indebted for the suggestion that such a work as this should be undertaken; to the former, for much help, encouragement, and almost daily correction of what had been written, or what had already been committed to the press.<br><br>How deeply I am under obligation to the great library of the British Museum will be clear to ever}' one who may turn over the following pages: especially do I owe much to Mr J. P. Gilson, Keeper of the Manuscripts; Mr G. F. Hill, Keeper of Coins and Medals; and Mr Arthur I. Ellis, Assistant in the Printed Book Department, who has often enabled me to consult books which from imperfect information I could not find in the excellent and almost unrivalled catalogue of the Printed Books of this magnificent institution. In the Bodleian Library, the assistance of Mr T. Gambier-Parry has been given to me, as ever, in the most generous manner.