Kinahan — On Irish Marbles and Limestones. 37 & 



The major portion of the other limestones, as a rule, give 

 more or less dark-coloured limes ; while some from the metamor- 

 phic limestones, especially those of Ulster, are so dark as to appear 

 more like brick- dust than lime ; in general, however, they are- 

 good strong limes. Most of those from the rocks of Carboniferous 

 age give a good return, but the returns from the Metamorphic 

 rocks are usually below the average. 



The strength and durability of lime made from some of these 

 limestones are shown in ancient, and even modern structures. In 

 various places, in the ruins of the ancient castles and other build- 

 ings, it can be seen that as the buildings came to be demolished, the 

 mortar proved stronger than the stone. This is well exemplified 

 in the old castle in the Flats of the Shannon, near Clonmacnoise, 

 which was built on an artificial clay mound. When the Shannon 

 cut away the clay foundation the castle fell in masses, the weight 

 of the latter breaking through the stones, while the mortar re- 

 mained unbroken. The Round Tower, Kilmacduagh, Co. Galway, 

 leans over considerably out of the perpendicular, and has not 

 given way, although some years ago it was struck by lightning,, 

 and cracked at the top. A modern example of good work was the 

 garden wall at Cowper's Hill, Queen's Co., built some hundred 

 years ago. This had to be removed, but as both the bricks and 

 mortar were of such excellent qualities, that the wall could not be 

 pulled down without great expense and labour, it was cut into 

 junks, and moved to its new site. 



As stated, in some places the limestones are hydraulic. These 

 were used in various waterworks, constructed some years ago, the 

 localities for the different stones being then known ; a list was 

 drawn up some thirty years ago by Griffith, but it was never 

 published, and now it seems to be lost. 1 



The localities at present known for hydraulic limestones will 

 be given in their respective counties ; but these will not embrace 

 all that really exist, as the published records are scant. 



The natural cements are not of the same value now as they 

 were formerly; for, as "Wilkinson and General H. Y. D. Scott, R. E. 



1 The late Mr. John Byron informed us it was, he helieved, destroyed by Griffith, 

 who considered it useless, as "natural cements" (made from hydraulic limestone) had 

 been superseded by artificial cements. 



