When the Highland Society of Scotland were engaged in preparing their report on the poems of Ossian, they thought it important to search with all possible diligence after such sources of ancient Gaelic poetry as might have been open to Macpherson, and especially for such written remains as might still be found in the country. Among others they applied to the Highland Society of London, whose secretary at the time, Mr John Mackenzie, was an enthusiastic Highlander, and an excellent Gaelic scholar. The Society furnished several interesting manuscripts which they had succeeded in collecting, and among these an ancient paper book which has since been called the “Book of the Dean of Lismore.” This book, which now lies in the library of the Faculty of Advocates, Edinburgh, is a small quarto very much defaced, of about seven inches square, and one inch and a quarter in thickness. It is bound in a piece of coarse sheepskin, and seems to have been much tossed about. The manuscript is written in what may be called phonetic Gaelic, the words being spelled on the same principle as the Welsh and Manx, although the application of the principle is very different. “Athair,” _father_, is “Ayr;” “Saor,” _free_, is “Seyr;” “Fhuair,” _found_, is “Hoar;” “Leodhas,” _Lewis_, is “Looyss;” “iuchair,” _a key_, is “ewthir;” “ghràdh,” _love_, is “Zrau.” This principle of phonetic spelling, with a partial admission of the Irish eclipsis and the Irish dot in aspiration, distinguishes the whole manuscript, and has made it very difficult to interpret. The letter used is the English letter of the 15th and 16th centuries, and the MS. was transcribed by the late Mr Ewen M’Lachlan of Aberdeen, an admirable Gaelic scholar. But no attempt was made to transfer its contents into modern Gaelic, or to interpret them, save in the case of a few fragments which were transferred and interpreted by Dr Smith for the Highland Society. Recently, however, the whole manuscript, with few exceptions, has been transcribed, presented in a modern Gaelic dress, translated and annotated, by the writer; and a historical introduction and additional notes have been furnished by Dr W. F. Skene.