Unavoidable circumstances have precluded the complete collation of the transcripts used in the compilation of this volume with their originals at Rome. The Urbino News Letters have indeed been collated for the whole period comprised in the volume; but with this exception documents dated later than June, 1578, or of problematical date, cannot be relied upon as in all respects authentic. Past experience, however, has established the reputation of Mr. Bliss and his Italian transcribers; and if they sometimes failed to indicate the precise page of a volume from which an extract had been made, as the numbers of the volumes are invariably given and the letters are dated, the verification of the references should present no difficulty.
By inadvertence the Preface to the first volume of the Calendar was not signed by the author, Mr. J. M. Rigg.
His thanks are due to Sir W. H. Grattan Flood, Mus. Doc., K.S.G., for invaluable help in correcting errors in the spelling of Irish proper names.