am convinced that Volcano's lie dormant for several years, nay even for
centuries, as probably was the case of Vesuvius before its eruption in
the reign of Titus, and certainly was so before that of the year 1631.
When I arrived at Naples in 1764, Vesuvius was quiet, very seldom smoak
was visible on its top; in the year 1766, it seemed to take fire, and
has never since been three months without either throwing up red hot
stones, or disgorging streams of lava, nor has its crater been ever free
from smoak. At Naples, when a lava appears, and not till then, it is
styled an eruption; whereas I look upon the five nominal eruptions I
have been witness to, from March 1766 to May 1771, as, in effect, but
one continued eruption.
[7] It is certain, that, by constant attention to the smoak that issues
from the crater, a very good guess may be given as to the degree of
fermentation within the Volcano. By this alone I foretold[47] the two
last eruptions, and, by another very simple observation, I pointed out,
some time before, the very spot from whence the lava has issued. When
the cone of Vesuvius was covered with snow, I had remarked a spot on
which it would not lie: concluding very naturally that this was the
weakest part of the cone, and that the heat from within prevented the
snow from lying; it was as natural to imagine that the lava, seeking a
vent, would force this passage sooner than another; and so indeed it
came to pass.
[8] These are his words: "Nubes (incertum procul intuentibus ex quo
monte Vesuvium fuisse postea cognitum est) oriebatur, cujus
similitudinem & formam, non alia magis arbor, quam pinus expresserit.
Nam longissimo veluti trunco elata in altum, quibusdam ramis
diffundebatur, credo quia recenti spiritu evecta, dein senescente eo
destituta, aut etiam pondere suo victa, in latitudinem evanescebat:
candida interdum, interdum sordida & maculosa, prout terram cineremve
sustulerat." Plin. lib. vi. ep. 16.
[9] The windows at Naples open like folding-doors.
[10] In several accounts of former eruptions of Vesuvius, I have found
mention of the ashes falling at a much greater distance; that, in the
year 472 and 473, they had reached Constantinople: Dio says, that during
the eruption of Vesuvius in the time of Titus--"tantus fuit pulvis ut ab
eo loco in Africam et Syriam et AEgyptum penetraverit." A book printed at
Lecce, in the kingdom of Naples, in MDCXXXII, and intituled, _Discorso
sopra l'origine de fuochi gettati dal Monte Vesuvio di Gio Francesco
Sorrata Spinola Galateo_, says, that the 16th of December, 1631, the
very day of the great eruption of Vesuvius (though perfectly calm), it
rained ashes at Lecce, which is nine days journey from the mountain:
that the day was darkened by them, and that they covered the ground
three inches deep; that ashes of a different quality fell at Bari the
same day; and that at both these places the inhabitants were very
greatly alarmed, not being able to conceive the occasion of such a
phaenomenon. Antonio Bulifon, in his account of the same eruption, says,
that the ashes fell, and lay several inches deep at Ariano in Puglia;
and I have been assured, by many persons of credit at Naples, that they
have been sensible of the fall of ashes, during an eruption, at above
two hundred miles distance from Vesuvius. The Abbate Giulio Cesare
Bracini, in his account of the eruption of Vesuvius, in 1631, says, that
the height of the column of smoak and ashes, taken from Naples by a
quadrant, was upwards of thirty miles. Though such uncertain
calculations demand but little attention; yet, by what I have seen, I am
convinced, that in great eruptions the ashes are sent up to so great a
height as to meet with extraordinary currents of air, which is the most
probable way of accounting for their having been carried to so great a
distance in a few hours. In a book, intituled, _Salvatoris Varonis
Vesuviani incendii Libri tres: Neapoli_, MDCXXXIV, I found a very
poetical description of the ashes that lay in the neighbourhood of
Vesuvius, after the eruption of 1631, in depth, from twenty to a hundred
palms: "Quare," says this author, "multi patrio in solo requirunt
patriam, et vix ibi se credunt vivere ubi certo sciant sese natos, adeo
totam loci speciem tempestas vertit."
[11] This conjecture has proved true; for, even in the month of April
1771, I again thrust sticks into some crevices of this lava, and they
immediately took fire. On Mount Etna, in 1769, I observed the lava, that
had been disgorged in 1766, smoak in many parts.
[12] In all accounts of great eruptions of Mount Etna and Mount
Vesuvius, I have found mention of this sort of lightning. Pliny the
younger, in his second letter to Tacitus upon the eruption of Vesuvius
in the time of Titus, says, that a black and horrible cloud covered them
at Misenum (which is above fifteen miles from the Volcano), and that
flashes of zig-zag fire, like lightning, but stronger, burst from it;
these are his words: "ab altero latere nubes atra et horrenda ignei
spiritus tortis vibratisque discursibus rupta, in longas flammarum
figuras dehiscebat; fulgoribus illae et similes et majores erant." This
was evidently the same electrical fire, and with which I am convinced
that the smoak of all Volcanos is pregnant. In several accounts of the
great eruption of Vesuvius in 1631, mention is made of damage done by
the lightning that issued from the column of smoak. Bulifon, in
particular, says, that, in the neighbourhood of the Volcano, people were
struck dead in the same manner as if by lightning, without having their
cloaths singed. Pliny mentions a like instance, which shews that the
ancients had observed this phaenomenon; for he says, that at Pompeii, the
day being fair, Marcus Herennius was struck dead by lightning. These are
his words; "In Catilianis prodigiis, Pompeiano ex municipio M. Herennius
Decurio _serena die_, fulmine ictus est." Plin. Hist. Nat. lib. II. cap.
LI. The learned and ingenious Father Beccaria, at Turin, assured me,
that he had been greatly pleased with my observations on this species of
lightning, as coinciding perfectly with several of his electrical
experiments.
[13] "I am well convinced, by this collection, that many variegated
marbles, and many precious stones, are the produce of Volcanos; and that
there have been Volcanos in many parts of the world, where at present
there are no traces of them visible." This is taken from a prior letter
to Lord Morton, dated April 7, 1767.
[14] In some accounts of an eruption of Vesuvius in 1660, I find mention
made of ashes which fell in the shape of crosses, and were looked upon
as highly miraculous; but in one book upon this subject, intituled,
_Athanasii Kircheri Soc. Jes. De prodigiosis crucibus, &c. Romae_,
MDCLXI, a very philosophical account is given of this phaenomenon; he
says, that, in 1660, from the 16th of August to the 15th of October,
Vesuvius cast up ashes, impregnated with nitrous, saline, and bituminous
sulphur, which upon linen garments took the form of crosses, probably
directed by the cross-threads in the linen, and therefore that the salts
did not shoot into such a shape when they fell upon garments of woollen;
a very particular description of these crosses may be found in page 38,
of the abovementioned book.
[15] I have since found in this stratum of erupted matter at Pompeii,
stones weighing eight pounds: but many accounts of the great eruption of
Vesuvius, particularly that of Antonio Bulifon, mention that a stone
like a bomb was thrown from the crater of Vesuvius in 1631; and fell
upon the Marquis of Lauro's house at Nola, which it set on fire. As Nola
is twelve miles from Vesuvius, this circumstance seems rather
extraordinary: however, I have seen stones of an enormous size shot up
to a very great height by Mount Vesuvius. In May 1771, having a stop
watch in my hand, I observed that one of these stones was eleven seconds
falling from its greatest height, into the crater from whence it had
been ejected. In 1767, a solid stone, measuring twelve feet in height,
and forty-five in circumference, was thrown a quarter of a mile from the
crater; the eruption of 1767, though by much the most violent of this
century, was, comparatively to those of the year 79 and 1631, very mild.
[16] See Letter V. in this collection.
[17] It is the common received opinion, that this mountain rose from the
bottom of the Lucrine lake. I had not seen the very curious and
particular account of its formation (which account is in my next letter)
when I wrote this, and was therefore in the same error.
[18] This must depend greatly upon the quality of the lava's; some have
been in a more perfect state of vitrification than others, and are
consequently less liable to the impressions of time. I have often
observed on Mount Vesuvius, when I have been close to the mouth from
whence a lava was disgorging itself, that the quality of it varied
greatly from time to time: I have seen it as fluid and coherent as glass
when in fusion: and I have seen it farinacious, the particles separating
as they forced their way out, just like meal coming from under the
grindstones. A stream of lava of this sort, being less compact, and
continuing more earthy particles, would certainly be much sooner fit for
vegetation, than one composed of the more perfect vitrified matter.
[19] This earthquake happened in the year 1693, and destroyed forty-nine
towns and villages, nine hundred and twenty-two churches, colleges, and
convents; and near one hundred thousand persons were buried in their
ruin.
[20] It is intituled, "A true and exact relation of the late prodigious
earthquake and eruption of Mount AEtna, or Monte Gibello; as it came in a
letter written to his Majesty from Naples, by the Right Honourable the
Earl of Winchelsea, his Majesty's late Embassador at Constantinople,
who, in his return from thence, visiting Catania in the island of
Sicily, was an eye-witness of that dreadful spectacle; together with a
more particular narrative of the same, as it is collected out of the
several relations sent from Catania; published by authority. Printed by
T. Newcomb, in the Savoy, 1669."
"I accepted, says the author, p. 38, the invitation of the Bishop of
Catania, to stay a day with him, that so I might be the better able to
inform your Majesty of that extraordinary fire, which comes from Mount
Gibel, fifteen miles distant from that city, which, for its horridness
in the aspect, for the vast quantity thereof (for it is fifteen miles in
length, and seven in breadth), for its monstrous devastation and quick
progress, may be termed an inundation of fire, a flood of fire, cinders,
and burning stones, burning with that rage as to advance into the sea
six hundred yards, and that to a mile in breadth, which I saw; and that
which did augment my admiration was, to see in the sea this matter like
ragged rocks, burning in four fathom water, two fathom higher than the
sea itself, some parts liquid, and throwing off, not with great
violence, the stones about it, which, like a crust of a vast bigness,
and red hot, fell into the sea every moment, in some place or other,
causing a great and horrible noise, smoak, and hissing in the sea; and
that more and more coming after it, making a firm foundation in the sea
itself. I stayed there from nine a clock on Saturday morning, to seven
next morning;" (this must have been towards the middle or latter end of
April;) "and this mountain of fire and stones with cinders had advanced
into the sea twenty yards at least, in several places; in the middle of
this fire, which burnt in the sea, it hath formed like to a river, with
its banks on each side very steep and craggy; and in this channel moves
the greatest quantity of this fire, which is the most liquid, with
stones of the same composition, and cinders all red hot, swimming upon
the fire of a great magnitude; from this a river of fire doth proceed
under the great mass of the stones, which are generally three fathoms
high all over the country, where it burns, and in other places much
more. There are secret conduits or rivulets of the liquid matter, which
communicates fire and heat into all parts more or less, and melts the
stones and cinders by fits in those places where it toucheth them, over
and over again; where it meets with rocks or houses of the same matter
(as many are), they melt and go away with the fire; where they find
other compositions, they turn them to lime or ashes (as I am informed).
The composition of this fire, stones, and cinders, are sulphur, nitre,
quicksilver, sal ammoniac, lead, iron, brass, and all other metals. It
moves not regularly, nor constantly down hill[48]; in some places it
hath made the vallies hills, and the hills that are not high are now
vallies. When it was night, I went upon two towers, in divers places;
and could plainly see at ten miles distance, as we judged, the fire to
begin to run from the mountain in a direct line, the flame to ascend as
high and as big as one of the greatest steeples in your Majesty's
kingdoms, and to throw up great stones into the air; I could discern the
river of fire to descend the mountain of a terrible fiery or red colour,
and stones of a paler red to swim thereon, and to be some as big as an
ordinary table. We could see this fire to move in several other places,
and all the country covered with fire, ascending with great flames[49],
in many places, smoaking like to a violent furnace of iron melted,
making a noise with the great pieces that fell, especially those which
fell into the sea. A Cavalier of Malta, who lives there, and attended
me, told me, that the river was as liquid where it issues out of the
mountain, as water, and came out like a torrent with great violence, and
is five or six fathom deep, and as broad, and that no stones sink
therein. I assure your Majesty, no pen can express how terrible it is,
nor can all the art and industry of the world quench or divert that
which is burning in the country. In forty days time, it hath destroyed
the habitations of 27,000 persons; made two hills of one, 1000 paces
high apiece, and one is four miles in compass; of 20,000 persons, which
inhabit Catania, 3000 did only remain; all their goods are carried away,
the cannons of brass are removed out of the castle, some great bells
taken down, the city-gates walled up next the fire, and preparations
made to abandon the city.
"That night which I lay there, it rained ashes all over the city, and
ten miles at sea it troubled my eyes. This fire in its progress met with
a lake of four miles in compass; and it was not only satisfied to fill
it up, though it was four fathom deep, but hath made of it a mountain."
[21] I have heard since, from some of our countrymen who have measured
this tree, that its dimensions are actually as abovementioned, but that
they could perceive some signs of four stems having grown together, and
formed one tree.
[22] No great stress should be laid upon these observations, as the many
inconveniences we laboured under, and the little practice we had in such
nice operations, must necessarily have rendered them very inaccurate.
The Canon Recupero, who was our guide, attended Mess. Glover, Fullerton,
and Brydone, up Mount Etna in June 1770. The latter is a very ingenious
and accurate observer, and has taken the height of many of the highest
mountains in the Alps. His observations, as the Canon informed me, were
as follows: At the top of the mountain the quicksilver in the
thermometer was 9 degrees below freezing point, when at the foot of the
mountain it rose to 76. At the foot of the little mountain that crowns
the Volcano the barometer stood at 20 deg. 4-2/3', half way up this little
mountain it was at 19 deg. 6'; but the wind was too violent for them to
attempt any more observations. The barometer and thermometer were of
Fahrenheit's. Mr. Brydone remarked, as he went up in the night, that he
could distinguish the stars in the milky way with wonderful clearness,
and that the cold was much more intense than he had ever felt upon the
highest mountains of the Alps.
[23] This passage, in Cornelius Severus's poem upon Etna, seems to
confirm my opinion:
"Placantesque etiam caelestia numina thure
"Summo cerne jugo, vel qua liberrimus AEtna
"Improspectus hiat; tantarum semina rerum
"Si nihil irritet flammas, stupeatque profundum."
[24] A better account of the formation of _tufa_ will be seen in my next
letter.
[25] The dates of the eruptions of Mount Etna, recorded by history, are
as follows: Before the Christian aera four, in the years 3525. 3538.
3554. 3843. After Christ, twenty-seven have been recorded, 1175. 1285.
1321. 1323. 1329. 1408. 1530. 1536. 1537. 1540. 1545. 1554. 1556. 1566.
1579. 1614. 1634. 1636. 1643. 1669. 1682. 1689. 1692. 1702. 1747. 1755.
1766.
The dates of the eruptions of Vesuvius are as follows: After Christ--79.
203. 472. 512. 685. 993. 1036. 1043. 1048. 1136. 1506. [1538, the
eruption at Puzzole.] 1631. 1660. 1682. 1694. 1701. 1704. 1712. 1717.
1730. 1737. 1751. 1754. 1760. 1766. 1767. 1770. 1771.
[26] Pliny, in his account of these islands, in the IX chapter of the
third book of his Natural History, seems to confirm this opinion.
"Lipara cum civium Romanorum oppido, dicta a Liparo rege, qui successit
AEolo, antea Melogonis vel Meliganis vocitata, abest XII millia pass. ab
Italia, ipsa circuitu paulo minori. Inter hanc et Siciliam altera, antea
Therasia appellata, nunc Hiera; qui sacra Vulcano est, colle in ea
nocturnas evomente flammas. Tertia Strongyle, a Lipara millia passuum ad
exortum solis vergens, in qua regnavit AEolus, quae a Lipara liquidiore
flamma tantum differt: e cujus fumo equinam flaturi sint venti, in
triduum praedicere incolae traduntur; unde ventos AEolo paruisse
existimatum. Quarta Didyme, minor quam Lipara. Quinta Ericusa; sexta
Phoenicusa; pabulo proximarum relicta. NOVISSIMA, eademque Minima,
Evonymos."
[27] See Plate V.
[28] The Abate Giulio Cesare Bruccini describes very elegantly, in his
account of the eruption of Vesuvius in 1631, his having made an
observation of the like nature--his words are (after having
particularized the different strata of erupted matter lying one over
another)--"parendo appunto che la natura ci abbia voluto lasciare
scritto in questa terra tutti gli incendii memorabili raccontati delli
autori."
[29] These are his words, book II. chap. vi.
"De Pulvere Puteolano.
"Est etiam genus pulveris, quod efficit naturaliter res admirandas.
Nascitur in regionibus Baianis, et in agris municipiorum, quae sunt circa
Vesuvium montem, quod commixtum cum calce et caemento non modo caeteris
aedificiis praestat firmitates, sed etiam moles, quae construuntur in mari,
sub aqua solidescunt. Hoc autem fieri hac ratione videtur, quod sub his
montibus et terra ferventes sunt fontes crebri, qui non essent, si non
in imo haberent, aut de sulfure, aut alumine, aut bitumine ardentes
maximos ignes: igitur penitus ignis, et flammae vapor per intervenia
permanans et ardens, efficet levem eam terram, et ibi, qui nascitur
tophus, exugens est, et sine liquore. Ergo cum tres res consimili
ratione, ignis vehementia formatae in unam pervenerint mixtionem, repente
recepto liquore una cohaerescunt, et celeriter humore duratae solidantur,
neque eas fluctus, neque vis aquae potest dissolvere."
About Baia, Puzzole, and Naples, we have an opportunity of remarking the
truth of these last words. Several of the piers of the ancient harbour
of Puzzole, vulgarly called Caligula's bridge, and which are composed of
bricks joined with this sort of cement, are still standing in the sea,
though much exposed to the waves; and upon every part of the shore you
find large masses of brick-walls rounded and polished by friction in the
sea, the brick and mortar making one body, and appearing like a
variegated stone. Large pieces of old walls are likewise often cut out
into square pieces, and made use of in modern buildings instead of
stone.
Soon after the first quotation, Pliny says, "Si ergo in his locis
aquarum ferventes inveniuntur fontes, et in montibus excavatis calidi
vapores, ipsaque loca ab antiquis memorantur pervagantes in agris
habuisse ardores, videtur esse certum ab ignis vehementia ex topho
terraque, quemadmodum in fornacibus et a calce, ita ex his ereptum esse
liquorem. Igitur dissimilibus, et disparibus rebus correptis, et in unam
potestatem collatis, callida humoris jejunitas aqua repente satiata,
communibus corporibus latenti calore confervescit et vehementer effecit
ea coire, celeriterque una soliditatis percipere virtutem."
[30] Scipione Falcone, a very good observer, in his _Discorso naturale
delli cause et effetti del Vesuvio_, says, that he saw, after the
eruption of Vesuvius in 1631 (which was attended with hot water), the
mud harden almost to a stone in a few days; his words are these--"fatta
dura a modo di calcina e di pietra non altrimenti di cenere, perche dopo
alcuni giorni vi ci e caminato per sopra e si e conosciuta durissima che
ci vogliono li picconi per romperla." This account, with other
circumstances mentioned in this letter, make it highly probable, that
all the _tufas_ in the neighbourhood of Vesuvius have been formed by a
like operation.
[31] This piece is now in the Museum of the Royal Society, together with
other specimens, mentioned in this and in the following letter. M. M.
[32] Letter IV.
[33] Strabo, in his fifth book of Geography, says, "Supra haec loca situs
est Vesuvius mons agris cinctus optimis: dempto vertice, qui magna sui
parte planus, totus sterilis est, adspectu cinaereus, cavernasque
ostendens fistularum plenas et lapidum colore fuliginoso, utpote ab igni
exesorum, ut conjecturam facere possit ista loca quondam arsisse, et
crateras ignis habuisse, deinde materia deficiente restincta fuisse."
Diodorus Siculus, in his fourth book, describing the voyage of Hercules
into Italy, says, "Phlegraeus quoque campus is locus appellatur a colle
nimirum, qui AEtnae instar Siculae magnam vim ignis eructabat; nunc
Vesuvius nominatur, multa inflammationis pristinae vestigia reservans."
And Vitruvius, in the sixth chapter of the second book, says, "Non minus
etiam memoratur antiquitus crevisse ardores et abundasse sub Vesuvio
monte et inde evomuisse circa agros flammas." Tacitus, mentioning the
eruption of Vesuvius in the reign of Titus, seems to hint likewise at
former eruptions, in these words: "Jam vero novis cladibus, vel post
longam saeculorum repetitis afflictae, haustae aut abrutae fecundissima
Campaniae ora et urbs incendiis vastata."
[34] Bracini, in his account of the eruption of 1613, says, that he
found many sorts of sea shells on Vesuvius after that eruption; and P.
Ignatio, in his account of the same eruption, says, that he and his
companions picked up many shells likewise at that time upon the
mountain: this circumstance would induce one to believe, that the water
thrown out of Vesuvius, during that formidable eruption, came from the
sea.
[35] In book xi. c. 93. he observes, that about Sinuessa and Puteoli,
"Spiracula vocant--alii Caroneas scrobes, mortiferum spiritum
exhalantes." And Seneca, Nat. Quaest. lib. vi. cap. 28. "Pluribus Italiae
locis per quaedam foramina pestilens exhalatur vapor, quem non homini
ducere, non ferae tutum est. Aves quoque si in illum inciderint, antequam
coelo meliore leniatur, in ipso volatu cadunt, liventque corpora, et non
aliter quam per vim elisae fauces tument."
[36] I have remarked, that, after a great fall of rain, the degree of
heat in this water is much less, which will account for what the Padre
Torre says (in his book, entituled, _Histoire et Phenomenes du Vesuve_),
that, when he tried it in company with Monsieur de la Condamine, the
degree of heat, upon Reaumur's thermometer, was 68 deg.
[37] This very scarce volume has been presented by Sir William Hamilton
to the British Museum. M. M.
[38] Here again we have an example of the electrical fire attending a
great eruption.
[39] The cup, or crater, on the top of the new mountain is now covered
with shrubs; but I discovered at the bottom of it, in the year 1770,
amidst the bushes, a small hole, which exhales a constant hot and damp
vapour, just such as proceeds from boiling water, and with as little
smell; the drops of this steam hang upon the neighbouring bushes.
[40] The noxious vapours which Lucan mentions to have prevailed at
Nisida, favour my opinion as to its origin:
"--Tali spiramine Nesis
"Emittit stygium nebulosis aera saxis."
Lucan. lib. vi.