39 , 



After two such clear and positive assertions, so conclu-" 

 sive to the point, and from such authoritj^ it is not sur- 

 prizing, that the world should implicitly adopt an opinion 

 so effectually supported. 



But, as Mr. Desmarest's object in iuA'enting this the- 

 ory, the tendency of his opinions, and the use to which 

 he meant to apply them, are now fortunately discovered, 

 I hope to be excused, for requesting the public to rally 

 a little, and to examine into the truth of these positions 

 of the Academy, that have, no doubt, contributed much 

 to accredit the theory, which ascribes to basalt a volcanic 

 origin. 



As to the first, that basalt is almost every where found 

 mixed with scoria, the obvious mode of ascertaining its 

 truth seems to be, an examination of the accounts, given 

 by respectable writers, of different countries, where basalt 

 has been found; and I begin with Egypt, where it seems 

 to have been first noticed. 



Egypt has never been supposed a volcanic country; 

 nor does the place, where Strabo found basalt, bear any 

 marks of the irregularity of surface, the necessary effect 

 of volcanic eruptions; for Strabo describes it as a level 

 plain, through which he drove in a chariot. Mr. Desma- 

 rest himself, who must have been well acquainted with 

 volcanic countries, is so little pleased with this account 

 of Strabo's, that, notwithstanding his known accurac}', he 

 endeavours to invalidate his testimony, on the avithority of 

 Norden and Pococke. Still, however, the scoria of the 

 Academy escapes them all. 



r 2 The 



