It may, we think, be said without injustice, that when dealing with that part of the question which related to the _uses_ of the Round Towers, O’Brien was more successful in upsetting the theories of other people than in establishing his own. The purposes for which preceding antiquarians had severally claimed that the towers were built are almost endless; but Dr. Petrie has summarised the most prominent of them as follows:[24]--(1) Fire-temples; (2) places from which to proclaim the Druidical festivals; (3) Gnomons, or astronomical observatories; (4) Phallic emblems, or Buddhist temples; (5) Anchorite towers, or Stylite columns; (6) Penitential prisons; (7) Belfries; (8) Keeps, or Monastic Castles; (9) Beacons and Watch-towers. Both he and O’Brien agree in holding that the Round Towers were not appropriated to any one of these purposes exclusively, though they might have been used for two or more of them. It is with regard to the selection of these latter that the authors differ--Petrie adopting views (7), (8), (9); O’Brien, view (3), but with much reservation; view (4) absolutely, and adding another view of his own, namely, that they were sometimes devoted to memorial or sepulchral uses. It has been mentioned already that Moore charged him with plagiarism in respect of his adoption of view (4); but, like other charges from the same quarter, the assertion rests upon unstable grounds. O’Brien made no secret of the fact that on many points he shared the views of General Vallancey, for whom he invariably expresses respect, and even admiration; but he is careful to explain that, where their judgments happen to coincide, it is for very different reasons. “I wish it to be emphatically laid down,” he says in one place, “that I do not tread in General Vallancey’s footsteps.... I have taken the liberty to _chalk out my own road_”; and, in another, “Though his perseverance had rendered him (Vallancey) the best _Irishian_ of his age, and of many ages before him, yet he has committed innumerable blunders.” This goes to show that he was unlikely to adopt any theory merely because Vallancey held it; and to have arrived at the same conclusion by a wholly different road was surely not “plagiarism.” What is more, a reference to the published works of General Vallancey,[25] or even to such extracts from them as may be found in Dr. Petrie’s book, will, if we are not mistaken, give rise to some doubt of that author having ever distinctly maintained the Eastern, or pagan, origin of the Round Towers. His views are, however, so nebulous and shifting, that it is difficult to say whether he committed himself to any positive theory on the subject. Starting with the conjecture that the Round Towers may have been the work of “Phœnicians or Indo-Scythians,” he is soon found attributing them to certain “African sea-champions,” who, in his opinion, were the “Pheni,” being likewise, as he goes on to inform us, “a _Pelasgic_ tribe.” Next, he