424 [Proc, B.N.F.C., 



Journal of Archaeology," &c, &c, fully confirms this view, and 

 enables us to fix satisfactorily the order of succession, and approxi- 

 mate to at least some of the principal dates. We have first the 

 pagan stone forts, built without mortar, such as Dun ^Engus ; then 

 we have early Christian monastic enclosures, such as the one on 

 the Skelligs, very nearly resembling the forts. Often connected 

 with these are the saints' houses, and the small oratories, all built 

 without mortar. Then follow larger churches, in which mortar 

 begins to be introduced, and which show a gradual increase of 

 ornament round the windows, and square-headed doors Then 

 we find the arch gradually introduced, and when fully established, 

 for ornament as well as use, the peculiarities of the native Irish 

 style soon became merged into those of Western Europe. This 

 took place during the eleventh century. The transition from the 

 style of building without, to that with the arch, was taking place 

 throughout the tenth century, and was completed under King Brian 

 Boruma about the year iooo. Amongst other evidence may be 

 adduced the case of the church at Tomgraney, which still remains, 

 and the west door of which has the straight lintel of the earlier 

 style. This church is stated to have been built by Cormac 

 O'Cillen about a.d. 964, and may therefore be about the last of 

 this class. The churches, on the other hand, attributed to Brian 

 Boruma all have arched doorways, though without the richness of 

 decoration found in those known to belong to the later part of the 

 eleventh century. The towers nearly all bear tokens of belonging 

 to this transitional period, for we can see the gradual development 

 of the arch in their details. They belong, therefore, with little 

 doubt, to the tenth century. There are several towers very similar, 

 and apparently about the same age, still remaining in Scotland and 

 the Orkneys ; and circular towers, detached or nearly so, have been 

 found on the Continent in connection with churches which date 

 from the same period. Similar towers are also depicted in some 

 of the frescoes and manuscripts from the eighth to the eleventh 



