Kinahan — Slates and Clays {Bricks, fyc). 77 



tioned hereafter ; some of the structures built with them being both 

 elegant and durable. 



Most of the roofing slates are heavier than the English slates in 

 the market — this being due, in some measure, to the comparative 

 shallowness of the Irish quarries. It is well known that the deeper 

 the working the better the slate. For roofs in exposed places 

 heavy slates are better than light ones, as the latter would be 

 carried away by the wind. For this reason, in many places in 

 Donegal, Mayo, Galway, &c, thin flags are preferred on account 

 of their weight (vol. v., page 565). 



The best Irish slates occur principally in the " Slate Series," or 

 Upper division of the Ordovicians ; nevertheless very good slates 

 have been worked in the Cambrians, other parts of the Silurians, 

 Devonians, Carboniferous slates; inferior ones have been obtained 

 from the Coal-measures. 



The Irish slate quarries have been usually more or less injured 

 by their being injudiciously laid out and opened ; the waste is often 

 allowed to accumulate at the mouth of the working on the vein ; 

 and as the quarry is extended the heaps have to be removed at great 

 cost. Moreover, during the working, the waste is often thrown into 

 the worked portion of the quarry, from which it has to be removed 

 afterwards, if the vein is followad in depth. In many cases land- 

 lords have prevented quarries from being worked by asking too 

 high royalties. 



The following seem to be the principal slate-quarries which 

 have been, or are now being, worked : — 



Clare, .... Broadford, a good slate, once largely worked ; 



quarries north of Killaloe, to the west of 



Lough Derg, p. 78. 

 Cork, .... Glentane, near Mallow ; Audley Cove, near 



Ballydehob ; Sherkin Island, Baltimore 



Harbour ; Benduff, near Eosscarbery, 



p. 79. 

 Donegal, . . . Olentoun, near St. Johnstown, p. 81. 

 Down, .... Tullycavan, near Newtownards, p. 83. 

 Kerry, .... Valentia, famous for its large slabs, p. 84. 

 Kilkenny, ..." Ormond Quarry," Valley of the Lingaun, near 



Carrick-on-Suir, p. 8G. 



