VOL. LXXXV.] PHILOSOPHICAL TRANSACTIONS. 4QQ 



derous to remain long suspended in the air; it was besides replete with the ferilli, 

 or volcanic lightning, which was stronger than common lightning, just as Pliny 

 the Younger describes it in one of his letters to Tacitus, when he says " fulgoribus 

 illa3 et similes et majores erant." Vesuvius was at this time completely covered, 

 as were all the old black lavas, with a thick, coat of these fine light grey ashes 

 already fallen, which gave it a cold and horrid appearance; and in comparison of 

 the above-mentioned enormous mass of clouds, which certainly, however it may 

 contradict our idea of the extension of our atmosphere, rose many miles above 

 the mountain, it appeared like a mole-hill ; though the perpendicular height of 

 \'^esuvius from the level of the sea, is more than 36oO feet. 



To avoid prolixity and repetition, I need only say, that the storms of thunder 

 and lightning, attended at times with heavy falls of rain and ashes, catising the 

 most destructive torrents of water and glutinous mud, mixed with huge stones, 

 and trees torn up by the roots, continued more or less to afflict the inhabitants 

 on both sides of the volcano, till the 7th of July, when the last torrent de- 

 stroyed many hundred acres of cultivated land, between the towns of Torre del 

 Greco and Torre dell' Annunziata. Some of these torrents, both on the sea 

 side and the Somma side of the mountain, came down with a horrid rushing 

 noise; and some of them, after having forced their way through the narrow 

 gullies of the mountain, rose to the height of more than 20 feet, and were 

 nearly half a mile in extent. The mud of which the torrents were composedj 

 being a kind of natural mortar, has completely cased up, and ruined for the 

 present, some thousand acres of rich vineyards; for it soon becomes so hard, 

 that nothing less than a pick-axe can break it up; I say for the present, as I 

 imagine that hereafter the soil may be greatly improved by the quantity of saline 

 particles that the ashes from this eruption evidently contain. A gentleman of 

 the British factory at Naples, having filled a plate with the ashes that had fallen 

 on his balcony during the eruption, and sowed some pease in them, assured me 

 that they came up the 3d day, and that they continue to grow much faster than 

 is usual in the best common garden soil. 



I went on Mount Vesuvius, as soon as I thought I might do it with any de- 

 gree of prudence, which was not till the 30th of June, and then it was attended 

 with some risk. The crater of Vesuvius, except at short intervals, had been 

 continually obscured by the volcanic clouds ever since the l6th, and was so this 

 day, with frequent flashes of lightning playing in those clouds, and attended as 

 usual with a noise like thunder; and the fine ashes were still falling on Vesuvius, 

 but still more on the mountain of Somma. I went up the usual way by Resina, 

 attended by my old Cicerone of the mountain, Bartolomeo Pumo, with whom 

 I have been 68 times on the highest point of Vesuvius. I observed in my way 

 through the village of Resina that many of the stones of the pavement had been 



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