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taken their course over that which lies immediately above 

 the town, with which the theatre, and most of the houses 

 are filled. This is not vitrified lava, but a sort of soft 

 stone, composed of pumice, ashes, and burnt matter. 

 It is of the same nature with what the Italians call 

 Tufa, and is in general use for building, and is met with 

 only in those countries that have been subject to sub- 

 terraneous fires. As water frequently attends eruptions 

 of fire, doubtless the first matter that issued from Vesu- 

 vius, and covered Herculaneum, was in the state of li- 

 quid mud. 



Braccini descended into the crater (or hollow on the 

 top) of Vesuvius, a little before the eruption in 1631. 

 He observes, it was then five miles in circumference, and 

 about 1000 paces deep. Its sides were covered with 

 brush wood, and at the bottom there was a plain on 

 which cattle grazed. In the midst of this plain was a 

 narrow passage, through which by a winding path he de- 

 scended among rocks and stones into a more spacious 

 plain, covered with ashes. In this were three little 

 pools, one of hot water, bitter and corrosive beyond 

 measure ; another of water salter than that of the sea ; 

 the third hot, but tasteless. 



The great increase of the cone of Vesuvius, from 

 that time to this, naturally induces one to think, that 

 the whole cone was raised in like manner, as was also 

 that part of it now called Soinma. It seems, that this 

 was what the ancients termed Vesuvius, and that the 

 conical mountain, at present called by that name, has 

 been raised by the succeeding eruptions. 



From repeated observations, it appears, that all the 

 soil in the neighbourhood of Vesuvius, is composed 

 of different strata of erupted matter, to a great depth 

 below the level of the sea. And undoubtedly this vol- 

 cano took its rise from the bottom of the sea. The 

 soil from Capreae to Naples is of the same sort. And 

 that on which Naples stands, has been evidently pro- 

 duced by explosions, some of them on the very spot 

 whereon the city is built. All the high grounds round 



