258 DOMAIN III. ARGU.LACEO.US. 



ledged their inability to produce such a singular 

 machine. 



Antique. Clay slate was also occasionally used in the 

 arts by the ancients, for Wad, in his catalogue 

 of the Borgian Museum, has mentioned a frag- 

 ment of a small statue of a bluish grey slate, the 

 surface being white from decomposition. There 

 are also heads of battle-axes, of a grey clay slate, 

 veined with a deeper colour, probably from some 

 island in the South Sea. 



This substance is often, singularly contorted 

 in various fantastic forms, both on a large and 

 on a small scale, 



Gmelin supposes that the softer clays arise 

 from the decomposition of the harder ; and he 

 says that rock clay is sometimes used in build- 

 ing*, Dr. Buchanan, in his travels in the south 

 of Himjostan, observed a kind of clay, which, 

 when dug up and dried, becomes as solid as 

 brick, whence he has ngt improperly called it 

 tatirite. later ite. 



The materials concerning clay rock and clay 

 slate are unusually scanty, not only because 

 they are seldom used in the arts, but because 

 even geologists have paid far more attention to 

 the granitic and calcareous rocks than to the 



* kinn. 137- 



