LIMESTONES OE IRELAND. 221 Dublin, and of Kilkenny, Cask el, and Limerick present interesting examples of tliis transition period. Amongst tlie examples of domestic architecture ot a past age is the ruined Castle of Trim, of huge pro portions, and of the Norman style of construction. The walls are upwards of 13 feet thick, constructed of the limestone of the locality, roughly squared and coursed, but not dressed ; sandstones being used in the angles of the openings and the arches, in accordance with the Norman practice of building. 1 Muckruss Abbey, standing by the Lakes of Killarney, displays some good examples of limestone sculpture. Limestone of a bluish tint has recently been employed with excellent effect in ecclesiastical structures in Dublin and its vicinity, when combined with granite, or Portland oolite, for the angles and mouldings of doors and windows. The dark-coloured beds from the ‘ Calp ’ are liable to rapid decay, and have a gloomy aspect. 2 In some localities, however, they yield a hydraulic lime, and were employed by the Shannon commissioners for this valuable species of mortar. The ordinary limestone of Ireland weighs in average per cubic foot 170 lbs.; the extremes of weight being 159 and 180 lbs. The average weight 1 Wilkinson, Anc. Arch, of Ireland, p. 117. 2 As shown by the state of the walls of the Library of Trinity College, Dublin.