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II. 



ON IRISH ARENACEOUS ROCKS. By G. H. KINAHAN, 



M.E.LA., Etc. 



[In this Supplement information is given which was either omitted in my previous 

 Paper 1 on this subject, or has teen obtained since that Paper was written. A 

 classification of paving setts has not as yet appeared, which omission is now recti- 

 fied, while the subject of mosaic pavement is also referred to. I also give some infor- 

 mation as to the durability and selection of stones, taken from the valuable Papers of 

 Dr. Julien of New York.] 



[Read November 16, 1887.] 



The durability of building- stones and their selection is most 

 important ; therefore it may be allowable to refer to Papers by 

 Dr. Alexis A. Julien " On the Decay of the Building Stones of 

 New York City," abstracts of which appeared in the Trans. New 

 York Acad. Sci., 1883, pp. 67, &c, as in them there is interesting 

 and valuable information applicable more or less to the Irish stones. 

 The stones used in New York are principally sandstone, marble, 

 granite, and gneiss — over 80 per cent, being sandstones. In con- 

 sequence of the frequent fires in that city, stone buildings are pre- 

 ferred to frame-houses ; but, on account of the friable nature of the 

 stone generally used, brick and stucco have been much in request — 

 frame-houses being 42 - 5, brick and stucco 47*9, stone 9 - l, andiron 

 0'5 per cent, of the whole. 



Although in New York there are some excellent stone struc- 

 tures, the severe competition has caused great quantities of most 

 inferior sandstone to be employed in building. Some of the coarse 

 sandstones in use last only from 5 to 15 years, but the best fine 

 stones have lasted from 100 to 200 ; the coarse limestones last from 

 20 to 40 years, but some of the fine marbles have lasted 200 ; the 

 granites have lasted from 75 to 200 years ; while the gneiss appears 

 to be more durable. In the great majority of the buildings, how- 

 ever, sandstones of bad quality have been used. 



The durability of a stone depends partly upon the chemical 

 composition of its constituents and of their cement. " This in- 



1 Scientific Proceedings, R.D.S., vol. iv., p. 507. 



