An account of the Library would be incomplete if the Catalogue were left unnoticed. The first printed Catalogue was issued about 1710 in one thin volume, folio. We have now a printed Catalogue in nine folio volumes, which includes all the printed books in the Library at the end of the year 1872. The first volume of this Catalogue (A and B) was prepared under the direction of Dr. Todd, and issued in 1864. The work was then suspended, and not resumed until 1872, when a special editor, Mr. H. Dix. Hutton, was appointed, the time of the Library staff being fully employed otherwise. The Catalogue was completed Jan. 1, 1887, the expense of printing and paper alone having been £4,500. Since that time Mr. Hutton has been engaged in preparing a Supplementary Catalogue, to contain the subsequent accessions. When this has been completed up to the present time, it is intended to make it a Desk Catalogue, in which all new accessions will be inserted on printed slips. The Catalogue is primarily an author’s catalogue--that is to say, books are arranged under the names of their authors, where known. But by the liberal use of cross references and secondary entries, some of the advantages of a subject catalogue are obtained. In the Desk Catalogue now in preparation, the method adopted by the editor, Mr. Hutton, is as follows:--One copy of the printed slip is taken, and in the upper left-hand corner the proper subject heading is type-written by him, and this slip is then inserted in alphabetical order, according to this heading. This saves the expense of printing a fresh title for the secondary entry. Of our MSS. the earliest existing catalogue is that of 1688, which was compiled with great care. This is also the only catalogue at present accessible to readers at a distance, having been printed in Bernard’s _Catalogus Manuscriptorum Angliæ et Hiberniæ_. In the Library itself the catalogue most commonly used is one drawn up by Dr. John Lyon about 1745, which, however, only extends to Classis G. A more complete catalogue, extending to Classis M, was prepared by Dr. Henry J. Monck Mason, about the year 1814, for the Irish Commissioners of Public Records, with a view to publication. The terms proposed by Dr. Monck Mason and his specimen of the work were approved, and when the rough copy (in five volumes) was finished he was required to hand it over to the Board. Then the question of remuneration was raised, and it was discovered that no minute had been entered of the original engagement; and as some of the members of the Board had been changed, the engagement, in the absence of a written vote, was not held to be sufficient to outweigh considerations of public economy. [Illustration: BOOK RECESSES IN LIBRARY.]