113 
relates the following opinion, arising from the consideration of certain che¬ 
mical phenomena. 
“ Being/’ says this philosopher, “ but a mile distant from the powder- 
mills of Hackney, when they blew up, the great noise and shock it occa¬ 
sioned brought to my recollection what had lately happened at the Isle of 
Modunda, which it seems is all an uninhabited rock, and was split by an 
earthquake, and a part of it tumbled down, and sunk into the sea, upon 
which occasion there was heard first a prodigious noue like the roaring of 
cannon *, attended with a cloud of smoak.” 
* The famous Bishop Berkley gives us an account of an eruption of mount Vesuvius, in which 
he paints these “ pleasing dreadful scenes” with all the ability of a great master. I reached, says he, 
with much difficulty in the year 1 717, the middle of April, the top of mount Vesuvius, in which 
I saw a vast aperture full of smoke, which hindered me from seeing its depth and figure. I heard 
within that horrid gulf certain extraordinary sounds, which seemed to proceed from the bowels of the 
mountain, a sort of murmuring, sighing, dashing sound, and between whiles a noise like that of 
thunder or cannon, with a clattering like that of tiles falling from the tops of houses into the streets. 
Sometimes, as the wind changed, the smoke grew thinner, discovering a very ruddy flame, and the 
circumference of the crater streaked with red and several shades of yellow. After an hour’s stay, the 
smoke being moved by the wind, gave us short and partial prospects of the great hollow; in the flat 
bottom of which I could discern two furnaces almost contiguous; that on the left seeming about three 
yards over, glowung with ruddy flame, and throwing up red-hot stones, with an hideous noise , 
wdiich, as they fell back, caused the clattering already taken notice of. May 8, in the morning, I 
ascended the top of Vesuvius a second time, and found a different face of things. The smoke ascending 
upright, gave a full prospect of the crater, which, as I could judge, was about a mile in circum¬ 
ference, and an hundred yards deep. A conical mount had been formed since my last visit, in the 
middle of the bottom, which I could see was made by the stones, thrown up and fallen back again 
into the crater. In this new hill remained the two furnaces already mentioned. The one was seen 
to throw up every three or four minutes, with a dreadful sound, a vast number of red-hot stones, 
at least three hundred feet higher than my head, as I stood upon the brink; but as there was no wind, 
they fell perpendicularly back from whence they had been discharged. The other was filled with red- 
hot liquid matter, like that in the furnace of a glass-house; raging and working like the waves of the 
sea, with a short abrupt noise. This matter would sometimes boil over, and run down the side of 
the hill, appearing at first red-hot, but changing colour as it hardened and cooled. Had the wind 
driven in our faces, we had been in no small danger of stifling by the sulphureous smoke, or being 
killed by the masses of melted minerals, that wmre shot from the bottom. But as the wind was 
favourable, 1 had an opportunity of surveying this amazing scene for above an hour and a half toge¬ 
ther. On the fifth of June, after an horrid noise, the mountain was seen at Naples to work over; 
and about three days after, its thunders were renewed so, that not only the windows in the city, but 
all the houses shook. From that time it continued to overflow, and sometimes at night were seen 
columns of fire shooting upward from its summit. On the tenth, when all was thought to be over, 
the mountain again renewed its terrors, roaring and raging most violently. One cannot form a juster 
idea of the noise, in the most violent fits of it, than by imagining a mixed sound, made up of the 
raging of a tempest, the murmur of a troubled sea, and the roaring of thunder and artillery , 
confused all together. Though we heard this at the distance of twelve miles, yet it was very terrible. 
I therefore resolved to approach nearer to the mountain; and accordingly, three or four of us got into 
a boat, and were set ashore at a little town, situated at the foot of the mountain. From thence we 
rode about four or five miles, before we came to the torrent of fire that was descending from the side 
2 F 
