tunnel-vault with a pointed one over it, on which the roofing slabs were laid." Mr. Fergusson adduces Cormac's Chapel on the Rock of Cashel, St. Kevin's House or Kitchen at Glendalough, which he thinks "may belong to the seventh century;" and St. Columba's House at Kells, "and several others in various parts of Ireland, as all displaying the same peculiarity" in the stone roofing. [Illustration: Fig. 11. Section of St. Flannan's Church at Killaloe.] [Illustration: Fig. 12. Section of the Church of Killaghy.] Like some oratories and churches in Ireland, more simple and primitive than those just alluded to, the building on Inchcolm is an edifice consisting of a single vaulted chamber, analogous in form to the over-croft of the larger oratories or minor churches. The accompanying section of the old and small stone-roofed church of Killaghy, at the village of Cloghereen, near Killarney, is the result of an accurate examination of that building by Mr. Brash of Cork. Its stones look better dressed and more equal in size, but otherwise it is so exactly a section of the Inchcolm oratory, that it might well be regarded as a plan of it, intended to display the figure and mode of construction of its walls and stone roof, formed as that roof is of three layers--viz., 1. The layer consisting of the proper stones of the arch of the cell interiorly; 2. The layer of outer roofing stones placed exteriorly; and 3. The intermediate layer of lime, and grit or small stones, cementing and binding together these other two courses.[93]