From these we pass by easy gradations to the beehive cells and oratories of the early Christians. No such stone dwellings probably existed before the time of St. Patrick, or we should have found traces of them at Tara, or Armagh, or Telltown; but as none such existed in these royal seats of the Scots, we may fairly assume that for domestic purposes wood and turf alone were used. But as soon as the use of stone became prevalent for such purposes, as was the case with the introduction of Christianity, we soon find the round towers, with their accompanying churches, springing up in every corner of the land, and Irish architecture progressing steadily in a groove of its own, till its forms were modified, but not obliterated, by the changes introduced by the English conquerors. The history of their style from St. Patrick to the English conquerers has been so well written by Petrie, that little now remains to be said about that division. But the history of the preceding seven centuries still remains for some one with the leisure requisite to explore the country, and with patience and judgment sufficient to read aright the many enigmas which are still involved in it, although the main outlines of the story seem sufficiently clear and intelligible. If it were written out in detail and fully illustrated, it would prove a most valuable commentary on the dark period of the history of Ireland before the introduction of Christianity, and when the concomitant introduction of alphabetic writing first rendered her annals intelligible and trustworthy. In one other respect the study of these early monuments of Ireland seems to afford a subject of most engrossing interest. It is in Ireland that we first begin to perceive the threefold division, which, if it can be established, will lead to the most important ethnographical determinations. It appears that in this island the stone circles of the Scandinavians were introduced simultaneously with the dolmens of the Iberians or Aquitanians, and we can trace the rude barrows of the Celts growing up between them till they expanded into the great mounds of the Boyne. That these three forms ever were at any one time absolutely distinct is most unlikely, and equally so that they should have long remained so in the same country, even if it could be shown that at any one time they belonged to three separate races. Generally, however, it seems hardly doubtful that they do point to ethnographic peculiarities, which may become most important. Combined with their history and a knowledge of their uses, these monuments promise to rescue from oblivion one of the most curious chapters of Irish history, which without them might remain for ever unwritten. [Footnote 201: Stokes, 'Life of Petrie;' London, 1868, p. 99 _et seq._]