120 DOMAIN I. S1DEROUS. 



the top-stone, and continues for ten fathoms; 

 after which the quality improves with the in.- 

 creasing depth, till, at the twenty-fourth fathom 

 from the surface, the workmen arrive at the 

 most superior kind, called the bottom-stone. 

 The colour is grey blue; and the texture is so 

 close, that it will sound like a piece of metal. 

 The masses are separated from the rock by 

 wedges, driven by sledges of iron, and contain 

 from five to fourteen superficial square feet of 

 stone, r^j 



" As soon as this mass is freed by one man, 

 another stone-cutter, with a strong wide chisel 

 and mallet, is ready to cleave it to its proper 

 thinness, which is usually about one eighth of 

 an inch : the pieces are generally from a foot 

 square to two feet long, by one wide ; but the 

 flakes are sometimes large enough for tables 

 and tomb-stones*." 



STRUCTURE I. COMMON. 



Aspect 1. Ash grey slate, from Angers, in 

 France. 



Bluish grey slate, from Westmorland. 

 Purple or reddish purple slate, from Anglesea. 

 The same, with pyrites, &c. 



* Brayley's Beauties of England, ii. 32g. 



