498 PHILOSOPHICAL TRANSACTIONS. [aNNO i7Q5. 



Torre del Greco, allowing the unfortunate inhabitants hardly time to save their 

 lives; their goods and effects were totally abandoned, and indeed several of the 

 inhabitants, whose houses had been surrounded with lava while they remained 

 in them, escaped from them and saved their lives the following day, by coming 

 out of the tops of their houses, and walking over the scoriae on the surface of 

 the red-hot lava. 



When this lava is cooled sufficiently, which may not be till some months 

 hence, I shall be curious to examine whether the centre, or solid and compact 

 parts, of the lava that ran into the sea has taken, as it probably may, the pris- 

 matical form of basalt columns, like many other ancient lavas disgorged into the 

 water. The exterior of this lava at present, like all others, offers to the eye 

 nothing but a confused heap of loose scoriae. The lava over the cathedral, and 

 in other parts of the town, is upwards of 40 feet in thickness: the general 

 height of the lava during its whole course is about 12 feet, and in some parts 

 not less than a mile in breadth. I walked in the few remaining streets of the 

 town, and went on the top of one of the highest houses that was still standing, 

 though surrounded by the lava; I saw from thence distinctly the whole course of 

 the lava, that covered the best part of the town; the tops of the houses were 

 just visible here and there in some parts, and the timbers within still burning 

 caused a bright flame to issue out of the surface; in other parts, the sulphur 

 and salts exhaled in a white smoke from the lava, forming a white or yellow 

 crust on the scoriae round the spots where it issued with the most force. Often 

 I heard little explosions, and saw that they blew up, like little mines, fragments 

 of the scoriae and ashes into the air; I suppose them to have been occasioned 

 either by rarefied air in confined cellars, or perhaps by small portions of gun- 

 powder taking fire, as few in this country are without a gun and some little 

 portion of gunpowder in their houses. 



On Wednesday the 1 8th, the wind having for a very short time cleared away 

 the thick cloud from the top of Vesuvius, we discovered that a great part of its 

 crater, particularly on the west side opposite Naples, had fallen in, which it 

 probably did about 4 o'clock in the morning of this day, as a violent shock of an 

 earthquake was felt at that moment at Resina, and other parts situated at the 

 foot of the volcano. The clouds of smoke were mixed with the fine ashes, which 

 were of such a density as to appear to have the greatest difficulty in forcing their 

 passage out of the now widely extended mouth of Vesuvius, which certainly, 

 since the top fell in, cannot be much short of 2 miles in circumference. One 

 cloud heaped on another, and succeeding each other incessantly, formed in a 

 few hours such a gigantic and elevated column of the darkest hue over the moun- 

 tain, as seemed to threaten Naples with immediate destruction, having at one 

 time been bent over the city, and appearing to be much too massive and pon- 



