ITALY. LETTER V. 6t 



probability, that the Heffian bafalt-hills have been 

 produced and cryftallifed by fubterraneous fire* 

 Moreover, I can tell you at prefent, that fome of 

 the Paduan, Vicentine, and Veronefe lava-hills, 

 are columnar-bafaltes, either entirely or in part; 

 and that Mr. Defmarets, travelling through thefe 

 parts, has been induced by them, to prefent a 

 DifTertation to the Academy at Paris, and to ex- 

 plain the origin of bafaltes by fubterraneous fire 

 and its fufions. This has been oppofed by that 

 great naturalift, Mr. Gueftard-, who, in his trea- 

 tife on bafaltes, afcribes its origin to an aqueous 

 cryftallifation, and cannot conceive how regular or 

 cryftallifed bodies can be produced by fufion. I 

 certainly do not conceive it neither ; but I find 

 in the greateft part of the Vicentine, Veronefe, 

 and Paduan lavas, an infinite quantity of white 

 polygdne iherl-cryftallifations, whofe figure is as 

 regular, and ftill more polygon, than the bafaltes ; 

 and can be fuppofed to have been formed in the 

 lava during its preparation or fluidity, as fuch in- 

 numerable quantities of cryftallized fherl, in fuch 

 a fhape and figure, have not been, till now, found 

 in any mountain or part of the world ; and, for 

 this reafon> not to mention many other difficul- 

 ties, it feems almoft improbable to fuppofe them, 

 in fuch aftoniming plenty, pre-exifting in the bot- 

 tom of all the Italian volcanos, and thence to 



have 



