470 DOMAIN XII. VOLCANIC. 



extinct volcanoes in the Campania of Rome. 

 Breislak, an eminent mineralogist, has minutely 

 discussed the leucite, in his interesting travels in 

 those parts of Italy : and as the nature of his 

 work rather precludes any hope of its being 

 Breisiak's de- translated, his accounts of the summit of Vesu- 



scnption of 



Vesuvius, yius, and of the noted eruption of 1794, which 

 are more scientific than any other descriptions, 

 shall be here given ; after premising that Vesu- 

 vius forms, as it were, a part of a larger moun- 

 tain, called Somma, which, in a semicircular 

 form, includes on the north the summit of this 

 celebrated volcano. 



Cone. " The present cone of Vesuvius is truncated, 



so as to form an inclined plane, sloping from the 

 north east to the south-west. The circumfer- 

 ence of the summit, which forms the brim of the 

 cauldron, is about 3000 feet ; and at the bottom 

 is distinguished an oblong plain, the greatest 

 diameter of which is from east to west. Having 

 since ascended several times to the top of the 

 cone, I perceived that its depth had gradually 

 diminished, and that the bottom of the crater 

 became higher daily, owing to the different mat- 

 ter which falls down, especially from the almost 

 perpendicular sides on the east and north. One 

 may at this time easily scan the extent and depth 





