the late Eruption of Mount Vesuvius. 8 1 
form of a pine tree, and from the greater or less quantity of 
the ferilli, or volcanic electricity, with which those clouds ap- 
pear to be charged. 
During thirty years that I have resided .at Naples, and in 
which space of time I have been witness to many eruptions of 
Vesuvius, of one sort or other, I never saw the gigantic cloud 
abovemen tioned replete with the electric fire, except in the 
two great eruptions of 1767, that of 1779, and during this 
more formidable one. The electric fire, in the year 1 779, that 
played constantly within the enormous black cloud over the 
crater of Vesuvius, and seldom quitted it, was exactly similar 
to that which is produced, on a very small scale, by the con- 
ductor of an electrical machine communicating with an insu- 
lated plate of glass, thinly spread over with metallic filings, 
&c. when the electric matter continues to play over it in zig- 
zag lines without quitting it. I was not sensible of any noise 
attending that operation in 1779; whereas the discharge of 
the electrical matter from the volcanic clouds during this erup- 
tion, and particularly the second and third days, caused explo- 
sions like those of the loudest thunder ; and indeed the storms 
raised evidently by the sole power of the volcano, resembled 
in every respect all other thunder-storms ; the lightning 
falling and destroying every thing in its course. The house 
of the Marquis of Berio at S. lorio, situated at the foot of 
Vesuvius, during one of these volcanic storms was struck with 
lightning, which having shattered many doors and windows, 
and damaged the furniture, left for some time a strong smell 
of sulphur in the rooms it passed through. Out of these gi- 
gantic and volcanic clouds, besides the lightning, both during 
this eruption and that of 1779, I have, with many others, 
MDCCXCV. M 
