The practice of building with wood was the favourite one amongst the “Scots”[11] in Ireland, and we shall find further examples amongst their disciples both in Scotland and England. Dr. Reeves states that the “Scotic” attachment to wooden churches continued in Ireland till the twelfth century, and that although stone churches existed, they were regarded as of foreign introduction. These wooden structures, it is needless to remark, have all long since disappeared, having been replaced by more permanent edifices. Although building with wattles and wood was the usual form of construction in Ireland in the early centuries, it was not the only one. When monasteries were established (as above mentioned) within the “raths” or fortresses by the chiefs, certain native forms of building in stone were found to exist in connection with these structures.[12] The rath was invariably surrounded with a lofty wall of great thickness, composed of unhewn stones mingled with earth. The exterior face of the wall was carefully built with “headers,” and in many instances chambers were constructed in the thickness of the wall, and roofed with overlapping stones in the form of an arch, but without the radiating structure of a true arch.[13] Chambers of similar construction are also often found in the walls of the brochs, and in the Eirde houses and other Celtic structures in Scotland. [Illustration: FIG. 2.--Beehive Cell on Skellig Mhichel. (From _Scotland in Early Christian Times_.)] Besides the great “cashel” or enclosing rampart, other stone buildings existed within the rath. These consisted of circular or oval huts, built with unhewn stones without mortar. They are generally about 6 to 10 feet in diameter, and the interior has sometimes square angles. The walls are 3 to 4 feet in thickness, and rise perpendicularly to about 6 feet in height, when they begin to converge towards the centre, the stones overlapping as they rise with a curve till they nearly meet, when the aperture is covered in on top with flagstones. The external appearance of these primitive abodes presents a domed form like that of a beehive, from which circumstance they are called “beehive huts” (Fig. 2). There is invariably a small doorway about 4 feet high, with a straight lintel on top, and the jambs are always built, not perpendicularly, but with an inclination inwards as they rise. A small square opening in the roof, greatly splayed towards the interior, forms the window of the hut. Stone structures of this description were common in certain parts of Ireland in Pagan times.[14] These were the native originals from which the Irish monks derived the style of stone building which was afterwards adopted by them in certain localities, with modifications as time progressed.