96 DOMAIN XII.' VOLCANIC. 



observable in the columnar lavas, a rational 

 argument would arise that the basaltic co- 

 lumns have a different origin. Such is the 

 nature of lithology, that a very minute dif- 

 ference sometimes constitutes a wide dis- 

 tinction ; and Werner's system of external 

 characters rests on little tints and shades, 

 for which his sagacity found expressions ; 

 while many of them have been known be- 

 fore by experienced miners, who felt and 

 knew what they could not express ; as a 

 shepherd cannot impart the knowledge by 

 which he can discern any one sheep among 

 a thousand, a trivial circumstance in pas- 

 tural countries. 

 Orpins of The final opinion of Dolomieu, in which 



basaltin. 



he is joined by Spallanzani, who visited the 

 volcanic regions of Italy with great care, 

 though not perhaps with a sufficient expe- 

 rience in lithology, was that basaltin may 

 be produced either in the humid way, or 

 by volcanic fire. In submarine volcanoes, 

 if we listen to the French mineralogists, it 

 might be ejected by heat, and crystallised 

 in a more compact and beautiful form 



