192 Physical Notices on the Bay of Naples. 



Close to this a tabular variety occurs, which appears to have 

 been caused by the fracture of a great cake of lava a few inch- 

 es thick by another stream passing under it, which dividing it 

 into small angular plates has cemented them together, and 

 placed them at every possible inclination and direction. The 

 coulee of 1822, though in great part amorphous, in the fullest 

 sense of the word, has in one place a peculiar construction. 

 The plain of the Atrio del Cavallo being covered at the com- 

 mencement of the eruption by a great bed of cinders, (a show- 

 er of which fell so extensively as to lie finger-deep in Naples,) 

 the lava which succeeded seems to have had a sort of repul- 

 sion to that perfectly dry and impalpable powder, as when wa- 

 ter is thrown upon dry sand, and formed itself into blisters 

 over it in dome-like concavities, from the interior of which spi- 

 cular portions of the lava stretch towards the bed of ashes be- 

 low in a very curious manner. 



This valley follows the curvilinear form of the Monte Som- 

 ma, and is terminated at the eastern end by a slope down to 

 the plain. At the opposite one it is divided into two ravines 

 by the mountain of tufa on which the hermitage of Saint 

 Salvador stands, (raised by the eruption of a. d. 79, not 1779, 

 as by a typographical error was printed in my former paper,) 

 the southern branch skirts the cone, and extends as far as the 

 lava of 1794, and that part of 1822 which devastated Torre 

 del Greco, the other forms, after a short distance, the defile 

 called the " Fossa Grande," a hollow washed out by the win- 

 ter torrents, and famous for the ejected masses and fine mine- 

 rals it contains, to which I shall presently allude. Between 

 the hermitage and the cone was the crater in which an un- 

 happy Frenchman plunged himself in 1820 in a fit of despair. 

 Three days he remained with the monks, and twice essayed to 

 bring his " courage to the sticking place ;" but the third time 

 he accomplished his dreadful purpose. The spot still retains 

 the name of " ii cratere del Francese." 



Combining the actual appearances with historical relation, 

 which we have not leisure to do here, there can be little doubt, 

 that previous to the year 79, when Herculaneum and Pompei 

 were overwhelmed, the Atrio del Cavallo was the centre of 

 the volcanic action, and the Monte Somma, in part at least, form- 



