O’Brien was resolved that, as the Academy would not publish his essay, he must do so himself; but in the meantime he had been engaged upon a translation of Dr. Villanueva’s _Ibernia Phœnicia_, which appeared in 1833. Personal liking for the author must have been his motive for undertaking this task, as his own views do not always harmonise with those of the Spanish _savant_; and certain letters which are quoted in the “Translator’s Preface” show that the two were very intimate. Having made this concession to friendship, he busied himself with the production of an enlarged and amended version of his essay. The first edition of this was published, early in 1834, by Whittaker & Co. of London, and J. Cumming of Dublin. It seems to have met with a ready sale, for a second edition appeared during the same year, bearing the imprint of Parbury & Allen, London, and J. Cumming, Dublin. Both editions are in octavo, and to outward appearance uniform, but differ in some respects. On the title-page of the first it is described as the “Prize Essay of the Royal Irish Academy, enlarged”--a description omitted in the second. Further, the title itself is given as “The Round Towers of Ireland (or the Mysteries of Freemasonry, of Sabaism, and of Budhism, for the first time unveiled)”; but the words within brackets are absent from the title-page of the second. A few corrections, too, appear in the latter edition; but, upon the whole, it is not much more carefully edited than the first--the curious omission of chapters vii. and xxxii. being common to both. What is known in the book-trade as “The Long Preface,” together with an amusingly comprehensive “Dedication,” is omitted from the second edition, a much more commonplace dedication to the Marquis of Lansdowne (described, of course, as “The Mæcenas of his age”) being substituted for the latter. As the second, and last, edition is that which had the author’s latest revisions, it has been thought advisable to reproduce it in the present issue. No interference with its text has been attempted--typography and pagination being alike preserved. Nor has anything in the shape of comment been inserted. A few supplementary additions to the original work will probably not be considered out of place. Together with this Introduction, they comprise a “Synopsis,” of which the object is to assist readers in following the track of the main argument--not always an easy task in the face of the author’s numerous divagations, annotated lists of the principal Round Towers and crosses, and an Index to the body of the work.