564 N A P 
magnitude. The larged, meafured by fir William Hamil¬ 
ton, was 108 feet in circumference and 17 in height. This 
was thrown at lead a quarter of a mile clear of the mouth 
of the volcano. Another, 66 feet in circumference and 
39 in height, being nearly of a fpherical figure, was 
throw'n out at the fame time, and lay near the former. 
This lad had the marks of being rounded, nay almod 
polifhed, by continual rolling in torrents or on the fea- 
fliore. Our author conjectures that it might be a fpheri¬ 
cal volcanic fait, fuch as that of 4.5 feet in circumference 
mentioned byM.de St. Fond in his Treatife of Extin- 
guidied Volcanoes. A third, of 16 feet in height and 92 
in circumference, was thrown much farther, and lay in 
the valley between Vefuvius and the Hermitage. It ap¬ 
peared alfo, from the large fragments that furrounded this 
mafs, that it had been much larger while in the air. 
From the time of this great eruption to the year 1784 
our author kept an exa£l diary of the operations of Vefu¬ 
vius, with drawings, fhowing, by the quantity of fmoke, 
the degree of fermentation within the volcano. The 
operations of the fubterraneous fire, however, appear to 
be very capricious and uncertain. One day there is the 
appearance of a violent fermentation, and the next every 
thing is tranquil; but, whenever there has been a con- 
fiderable ejection of fcoriseand cinders, it has beenacon- 
dant obfervation, that the lava loon made its appear¬ 
ance, either by boiling over the crater, or forcing its 
way through the crevices in the conical part of the moun¬ 
tain. An eruption took place in the month of November 
1784, and continued for fome time, but without any re¬ 
markable circumltance. 
Breidak, an Italian geologid, has given an account of 
the prefent date of Vefuvius, and an intereding defcrip- 
tion of the very remarkable eruption of 1794; the molt 
important particulars of which we lhall 1 'eleCt. This 
eruption was fo great as to change the very form of Ve¬ 
fuvius, as we have before obferved. 
“ The prefent cone of Vefuvius is truncated, fo as to 
form an inclined plane, Hoping from the north-ead to the 
fouth-wed. The circumference of the fummit, which 
forms the brim of the cauldron, is about 3000 feet; and 
at the bottom is didinguilhed an oblong plain, the greated 
diameter of which is from ead to wed. Having fince af- 
cended feveral times to the top of the cone, I perceived 
that its depth had gradually diminilhed, and that the bot¬ 
tom of the crater became higher daily, owing to the dif¬ 
ferent matter which falls down, efpecially from the almofl- 
perpendicular fides on the ead and north. One can at 
this time eafily fcan the extent and depch of its mouth, 
but occafionally it is much encumbered, and fometimes 
totally clogged. In 1755, the bottom of the funnel role 
fo confiderably, that it prefented a vad plain only twenty- 
three feet beneath the brim; and in the m’ldft of this 
plain was another cone from eighty to ninety feet high, 
with a fmall crater, from which the eruptions proceeded. 
Braccini has left us a curious defcription of the date of 
Vefuvius after a long period of red, and before the grand 
eruption of 1631. The whole of it, or at lead the greater 
part of it, had become acceldble. Having himfelf de- 
l’cended into the crater, he fays, he found it covered with 
plants and trees, and that a road down it was practicable 
for the fpace of a mile ; at this depth a very deep cavern 
was feen, which having pafled, the way was again open 
two miles by a very deep, but at the fame time very fafe, 
road, owing to the trees growing near to each other. At 
length a large plain prefented itfelf, furrounded by a num¬ 
ber of grottoes and caverns, which might be entered, but 
which the party were deterred from on account of their 
darknefs. This plain, which was not accedible otherwife 
than by a very rapid dope, nearly three miles in length, 
mud afluredly have been much beneath the level of the tea, 
“ When the volcano is at red, vapours are feen to rife 
from the cauldron’s brim, or from the interior of its fides, 
which are very perceptible. When the mouth of Vefuvius 
is obferved from any didance, and during the prevalence 
L E S. 
of moidure in the atmofphere, a mafs of vapour feems to 
rife from it which mingles with the clouds. 
“ The wedern portion of Sornma mud be confidered a* 
connefted with the cone of Vefuvius by a hill of fmaller 
eminence, denominated Monte Cantaroni, on which is the 
hermitage del Salvatore. This hill is interfered by three 
valleys, that delerve to be examined with attention on 
account of the quantity of primitive fubdances which 
the volcano has thrown thither during old eruptions. 
The northern valley is that termed La Folfa di Pharaone 
near the plain, and Vallone delia Vetrana in its more ele¬ 
vated part, where the current of lava fiowed in 1785. 
This vale, hollowed by rains, is the only interval between 
Mount Sornma and Mount Cantaroni. South of this 
vale are two others, nearly parallel, the fird called Rio 
Cupo, the fecond Fofi'a Grande, which, taking a direction 
from ead to wed, emerge in the plain of St. Jorio. Its 
northern fide, nearly perpendicular, rifes to a confiderable 
height above the valley; and, being compofed only of ce¬ 
mented fragments of porous lava, called capillo, of mafies 
of lpongy lava, and other fubdances of an inadhefive quality, 
is fubjeCt frequently to crumble and fall in large quanti¬ 
ties. Along the whole extent of the fouthern fide, at its 
upper part, is feen an ancient current of lava, which at 
fird fight appears to be feveral drata of lava impofed one 
on the other, but which a little attention fhows is but one 
current, in which horizontal chafms have been occafioned 
by refrigeration, and into which the wind has fince in¬ 
troduced a dight quantity of vegetable earth. This lava 
is hard and compaCt; it contains but few fragments of 
augite or pyroxene, and feems to be an ad'emblage of 
leucites, the fuperficial crydalline ludre of which, having 
been impaired by decompofition, makes it refemble va- 
riolite in its exterior. Many detached mafies of this 
current have fallen to the bottom of the valley. Each 
fall of matter brings down calcareous dones, mica, and 
mixtures of felfpar and vefuvian. The lava of 1767, 
which threatened the villages of La Barra and St. Jorio, 
difcliarged itfelf into this valley, which it filled to a Cer¬ 
tain height, and afterwards flowed farther, fpreading it¬ 
felf to the plain. As it is already covered by the crum- 
blings from the fides, in order to examine it, the in¬ 
quirer mud repair to the plain of St. Jorio, in the neigh¬ 
bourhood of the chapel of St. Vito. The lava of La Scala 
pafles beneath the garden of La Favorita. It is of the 
colour of aflies, whitifli, and of a crydallized grain. It 
contains many crydals of pyroxene, few of leucite, and 
fmall pieces of felfpar, in groups in its cavities. This 
lava, where it is hew n on the fea-fitore near La Cavalleria, 
is worthy of attention. Under an uniform bed, from fif¬ 
teen to twenty feet in thicknefs, the lava is found divided 
into drata of from three to four feet: thefe divifions are 
formed by parallel and horizontal lines; and, where thefe 
are dug down to, the lava is found to have feparated itfelf 
fpontaneoufiy into beds. Below them are large prifms, 
commonly hexagonal, which are disjoined with great 
eafe : in fome places thefe prifms, indead of the lower, 
are found in the upper, part of the current. The lame 
tendency to a bafidtic conformation, which is noticed in 
the lava of La Scala, is obferved again in the neighbour¬ 
ing current of Caladro. This, after pafling through a 
defile below Vallelonga, fpreads to a broad front on reach¬ 
ing the fea. What mod deferves obfervation in the lava 
here, are the fmall crydallizations it prefents, which feem 
to be the olivine of Werner. It is moreover of a deeper 
colour than the iava of Scala, more porous, and like that 
contains many crydals of augite and fragments of felfpar. 
“ Next to this lava is found that of the eruption of 1794. 
Of the diflerent eruptions of Vefuvius, that is the mod 
recent, and was one of the mod confiderable. Vefuvius 
had continued tranquil for a long time. On the 12th of 
June, 1794, towards eleven in the evening, a very violent 
fhock of an earthquake was felt, which induced many 
of the inhabitants of Naples to leave their houfes for the 
night. The tranquillity of the mountain did not, how¬ 
ever. 
