proceeded through the second or middle region of Etna, called La
Selvosa, _the woody_, than which nothing can be more beautiful. On every
side are mountains, or fragments of mountains, that have been thrown up
by various ancient explosions; there are some near as high as Mount
Vesuvius; one in particular (as the Canon our guide assured me, having
measured it) is little less than one mile in perpendicular height, and
five in circumference at its basis. They are all more or less covered,
even within their craters, as well as the rich vallies between them,
with the largest oak, chesnut, and firr trees, I ever saw any where; and
indeed it is from hence chiefly, that his Sicilian Majesty's dockyards
are supplied with timber. As this part of Etna was famous for its timber
in the time of the Tyrants of Syracusa, and as it requires the great
length of time I have already mentioned before the matter is fit for
vegetation, we may conceive the great age of this respectable Volcano.
The chesnut-trees predominated in the parts through which we passed,
and, though of a very great size, are not to be compared to some on
another part of the Regione Selvosa, called Carpinetto. I have been told
by many, and particularly by our guide, who had measured the largest
there, called La Castagna Cento Cavalli, that it is upwards of
twenty-eight Neapolitan canes in circumference. Now as a Neapolitan cane
is two yards and half a quarter, English measure, you may judge, Sir, of
the immense size of this famous tree[21]. It is hollow from age, but
there is another near it almost as large and sound. As it would have
required a journey of two days to have visited this extraordinary tree,
and the weather being already very hot, I did not see it. It is amazing
to me, that trees should flourish in so shallow a soil; for they cannot
penetrate deep without meeting with a rock of lava; and indeed great
part of the roots of the large trees we passed by are above ground, and
have acquired, by the impression of the air, a bark like that of their
branches. In this part of the mountain, are the finest horned cattle in
Sicily; we remarked in general, that the horns of the Sicilian cattle
are near twice the size of any we had ever seen; the cattle themselves
are of the common size. We passed by the lava of the last eruption in
the year 1766, which has destroyed above four miles square of the
beautiful wood abovementioned. The mountain raised by this eruption
abounds with sulphur and salts, exactly resembling those of Vesuvius;
specimens of which I sent some time ago to the late Lord Morton.
In about five hours from the time we had left the convent of St. Nicolo
dell' Arena, we arrived at the borders of the third region, called La
Netta, or Scoperta, _clean_ or _uncovered_, where we found a very sharp
air indeed; so that, in the same day, the four seasons of the year were
sensibly felt by us, on this mountain; excessive summer heats in the
Piemontese, spring and autumn temperature in the middle, and extreme
cold of winter in the upper region. I could perceive, as we approached
the latter, a gradual decrease of vegetation; and from large timber
trees we came to the small shrubs and plants of the northern climates: I
observed quantities of juniper and tanzey; our guide told us that later
in the season there are numberless curious plants here, and that in some
parts there are rhubarb and saffron in plenty. In Carrera's History of
Catania, there is a list of all the plants and herbs of Etna in
alphabetical order.
Night coming on, we here pitched a tent, and made a good fire, which was
very necessary; for without it, and very warm cloathing, we should
surely have perished with cold; and at one of the clock in the morning
of the 26th, we pursued our journey towards the great crater. We passed
over vallies of snow, that never melts, except there is an eruption of
lava from the upper crater, which scarcely ever happens; the great
eruptions are usually from the middle region, the inflamed matter
finding (as I suppose) its passage through some weak part, long before
it can rise to the excessive height of the upper region, the great mouth
on the summit only serving as a common chimney to the Volcano. In many
places the snow is covered with a bed of ashes, thrown out of the
crater, and the sun melting it in some parts makes this ground
treacherous; but as we had with us, besides our guide, a peasant well
accustomed to these vallies, we arrived safe at the foot of the little
mountain of ashes that crowns Etna, about an hour before the rising of
the sun. This mountain is situated in a gently inclining plain of about
nine miles in circumference; it is about a quarter of a mile
perpendicular in height, very steep, but not quite so steep as Vesuvius;
it has been thrown up within these twenty-five or thirty years, as many
people at Catania have told me they remembered when there was only a
large chasm or crater, in the midst of the abovementioned plain. Till
now, the ascent had been so gradual (for the top of Etna is not less
than thirty miles from Catania, from whence the ascent begins) as not to
have been the least fatiguing; and if it had not been for the snow, we
might have rode upon our mules to the very foot of the little mountain,
higher than which the Canon our guide had never been: but as I saw that
this little mountain was composed in the same manner as the top of
Vesuvius, which, notwithstanding the smoak issuing from every pore, is
solid and firm, I made no scruple of going up to the edge of the crater;
and my companions followed. The steep ascent, the keenness of the air,
the vapours of the sulphur, and the violence of the wind, which obliged
us several times to throw ourselves flat upon our faces to avoid being
overturned by it, made this latter part of our expedition rather
inconvenient and disagreeable. Our guide, by way of comfort, assured us,
that there was generally much more wind in the upper region at this
time.
Soon after we had seated ourselves on the highest point of Etna, the sun
arose, and displayed a scene that indeed passes all description. The
horizon lighting up by degrees, we discovered the greatest part of
Calabria, and the sea on the other side of it; the Phare of Messina, the
Lipari Islands; Stromboli, with its smoaking top, though at above
seventy miles distance, seemed to be just under our feet; we saw the
whole island of Sicily, its rivers, towns, harbours, &c. as if we had
been looking on a map. The island of Malta is low ground, and there was
a haziness in that part of the horizon, so that we could not discern
it; our guide assured us, he had seen it distinctly at other times,
which I can believe, as in other parts of the horizon, that were not
hazy, we saw to a much greater distance; besides, we had a clear view of
Etna's top from our ship, as we were going into the mouth of the harbour
of Malta some weeks before; in short, as I have since measured on a good
chart, we took in at one view a circle of above nine hundred English
miles. The pyramidal shadow of the mountain reached across the whole
island, and far into the sea on the other side. I counted from hence
forty-four little mountains (little I call them in comparison of their
mother Etna, though they would appear great any where else) in the
middle region on the Catania side, and many others on the other side of
the mountain, all of a conical form, and each having its crater; many
with timber trees flourishing both within and without their craters.
The points of those mountains that I imagine to be the most ancient are
blunted, and the craters of course more extensive and less deep than
those of the mountains formed by explosions of a later date, and which
preserve their pyramidal form entire. Some have been so far mouldered
down by time, as to have no other appearance of a crater than a sort of
dimple or hollow on their rounded tops, others with only half or a third
part of their cone standing; the parts that are wanting having mouldered
down, or perhaps been detached from them by earthquakes, which are here
very frequent. All however have been evidently raised by explosion; and
I believe, upon examination, many of the whimsical shapes of mountains
in other parts of the world would prove to have been occasioned by the
same natural operations. I observed that these mountains were generally
in lines or ridges; they have mostly a fracture on one side, the same as
in the little mountains raised by explosion on the sides of Vesuvius,
of which there are eight or nine. This fracture is occasioned by the
lava's forcing its way out, which operation I have described in my
account of the last eruption of Vesuvius. Whenever I shall meet with a
mountain, in any part of the world, whose form is regularly conical,
with a hollow crater on its top, and one side broken, I shall be apt to
decide such a mountain's having been formed by an eruption; as both on
Etna and Vesuvius the mountains formed by explosion are without
exception according to this description. But to return to my narrative.
After having feasted our eyes with the glorious prospect above-mentioned
(for which, as Spartian tells us, the Emperor Adrian was at the trouble
of ascending Etna), we looked into the great crater, which, as near as
we could judge, is about two miles and a half in circumference; we did
not think it safe to go round and measure it, as some parts seemed to
be very tender ground. The inside of the crater, which is incrusted with
salts and sulphurs like that of Vesuvius, is in the form of an inverted
hollow cone, and its depth nearly answers to the height of the little
mountain that crowns the great Volcano. The smoak, issuing abundantly
from the sides and bottom, prevented our seeing quite down; but the wind
clearing away the smoak from time to time, I saw this inverted cone
contracted almost to a point; and, from repeated observations, I dare
say, that in all Volcanos, the depth of the craters will be found to
correspond nearly to the height of the conical mountains of cinders
which usually crown them; in short, I look upon the craters as a sort of
suspended funnels, under which are vast caverns and abysses. The
formation of such conical mountains with their craters are easily
accounted for, by the fall of the stones, cinders, and ashes, emitted at
the time of an eruption.
The smoak of Etna, though very sulphureous, did not appear to me so
fetid and disagreeable as that of Vesuvius; but our guide told me, that
its quality varies, as I know that of Vesuvius does, according to the
quality of the matter then in motion within. The air was so very pure
and keen in the whole upper region of Etna, and particularly in the most
elevated parts of it, that we had a difficulty in respiration, and that,
independent of the sulphureous vapour. I brought two barometers and a
thermometer with me from Naples, intending to have left one with a
person at the foot of the mountain, whilst we made our observation with
the other, at sun-rising, on the summit; but one barometer was unluckily
spoilt at sea, and I could find no one expert enough at Catania to
repair it: what is extraordinary, I do not recollect having seen a
barometer in any part of Sicily. At the foot of Etna, the 24th, when we
made our first observation, the quicksilver stood at 27 degrees 4
lines; and the 26th, at the most elevated point of the Volcano, it was
at 18 degrees 10 lines. The thermometer, on the first observation at the
foot of the mountain was at 84 degrees, and on the second at the crater
at 56[22]. The weather had not changed in any respect, and was equally
fine and clear, the 24th and 26th. We found it difficult to manage our
barometer in the extreme cold and high wind on the top of Etna; but,
from the most exact observations we could make in our circumstances, the
result was as abovementioned. The Canon assured me, that the
perpendicular height of Mount Etna is something more than three Italian
miles, and I verily believe it is so.
After having passed at least three hours on the crater, we descended,
and went to a rising ground, about a mile distant from the upper
mountain we had just left, and saw there some remains of the foundation
of an ancient building; it is of brick, and seems to have been
ornamented with white marble, many fragments of which are scattered
about. It is called the Philosopher's Tower, and is said to have been
inhabited by Empedocles. As the ancients used to sacrifice to the
celestial gods on the top of Etna[23], it may very well be the ruin of a
temple that served for that purpose. From hence we went a little further
over the inclined plain abovementioned, and saw the evident marks of a
dreadful torrent of hot water, that came out of the great crater at the
time of an eruption of lava in the year 1755, and upon which phaenomenon
the Canonico Recupero, our guide, has published a dissertation. Luckily
this torrent did not take its course over the inhabited parts of the
mountain; as a like accident on Mount Vesuvius in 1631 swept away some
towns and villages in its neighbourhood, with thousands of their
inhabitants. The common received opinion is, that these eruptions of
water proceed from the Volcanos having a communication with the sea; but
I rather believe them to proceed merely from depositions of rain water
in some of the inward cavities of them. We likewise saw from hence the
whole course of ancient lava, the most considerable as to its extent of
any known here; it ran into the sea near Taormina, which is not less
than thirty miles from the crater whence it issued, and is in many parts
fifteen miles in breadth. As the lavas of Etna are very commonly fifteen
and twenty miles in length, six or seven in breadth, and fifty feet or
more in depth; you may judge, Sir, of the prodigious quantities of
matter emitted in a great eruption of this mountain, and of the vast
cavities there must necessarily be within its bowels. The most extensive
lavas of Vesuvius do not exceed seven miles in length. The operations of
nature on the one mountain and the other are certainly the same; but on
Mount Etna, all are upon a great scale. As to the nature and quality of
their lavas, they are much the same; but I think those of Etna rather
blacker, and in general more porous, than those of Vesuvius. In the
parts of Etna that we went over, I saw no stratas of pumice stones,
which are frequent near Vesuvius, and cover the ancient city of Pompeii;
but our guide told us, that there are such in other parts of the
mountain. I saw some stratas of what is called here _tufa_; it is the
same that covers Herculaneum, and that composes most of the high grounds
about Naples; it is, upon examination, a mixture of small pumice stones,
ashes, and fragments of lava, which is by time hardened into a sort of
stone[24]. In short, I found, with respect to the matter erupted,
nothing on Mount Etna that Vesuvius does not produce; and there
certainly is a much greater variety in the erupted matter and lavas of
the latter, than of the former; both abound with pyrites and
crystallizations, or rather vitrifications. The sea shore at the foot of
Etna, indeed, abounds with amber, of which there is none found at the
foot of Vesuvius. At present there is a much greater quantity of sulphur
and salts on the top of Vesuvius than on that of Etna; but this
circumstance varies according to the degree of fermentation within; and
our guide assured me, he had seen greater quantities on Etna at other
times. In our way back to Catania, the Canon shewed me a little hill,
covered with vines, which belonged to the Jesuits, and, as is well
attested, was undermined by the lava in the year 1669, and transported
half a mile from the place where it stood, without having damaged the
vines.
In great eruptions of Etna, the same sort of lightning, as described in
my account of the last eruption of Vesuvius, has been frequently seen to
issue from the smoak of its great crater. The antients took notice of
the same phaenomenon; for Seneca (lib. ii. Nat. Quaest.) says,--"AEtna
aliquando multo igne abundavit, ingentem vim arenae urentis effudit,
involutus est dies pulvere, populosque subita nox terruit, _illo tempore
aiunt plurima fuisse tonitrua et fulmina_."
Till the year 252 of Christ, the chronological accounts of the eruptions
of Etna are very imperfect: but as the veil of St. Agatha was in that
year first opposed to check the violence of the torrents of lava, and
has ever since been produced at the time of great eruptions; the
miracles attributed to its influence, having been carefully recorded by
the priests, have at least preserved the dates of such eruptions. The
relicks of St. Januarius have rendered the same service to the lovers of
natural history, by recording the great eruptions of Vesuvius. I find,
by the dates of the eruptions of Etna, that it is as irregular and
uncertain in its operations as Vesuvius[25]. The last eruption was in
1766.
On our return from Messina to Naples, we were becalmed three days in the
midst of the Lipari islands, by which we had an opportunity of seeing
that they have all been evidently formed by explosion[26]; one of them,
called Vulcano, is in the same state as the Solfaterra. Stromboli is a
Volcano, existing in all its force, and, in its form of course, is the
most pyramidal of all the Lipari Islands; we saw it throw up red hot
stones from its crater frequently, and some small streams of lava issued
from its side, and ran into the sea[27]. This Volcano differs from Etna
and Vesuvius, by its continually emitting fire, and seldom any lava;
notwithstanding its continual explosions, this island is inhabited, on
one side, by about an hundred families.
[Illustration: _Plate V._
STROMBOLI, one of the LIPARI ISLANDS.]
These, as well as I can recollect, are all the observations that I made
with respect to Volcanos, in may late curious tour of Sicily; and I
shall be very happy should the communication of them afford you, or any
of our countrymen (lovers of natural history) satisfaction or
entertainment.
I am,
SIR,
With great regard and esteem,
Your most obedient
humble servant,
W. HAMILTON.
LETTER V.
To MATHEW MATY, M. D. Secretary to the Royal SOCIETY.
REMARKS upon the NATURE of the SOIL of NAPLES, and its Neighbourhood.
"Mille miracula movet saciemque mutat locis, et defert montes,
subrigit plana, valles extuberat novas, in profundo insulas
eregit."
SENECA, De Terra-motu.
Naples, Oct. 16, 1770.
SIR,
According to your desire, I lose no time in sending you such further
remarks as I have been making with some diligence, for six years past,
in the compass of twenty miles, or more, round this capital. By
accompanying these remarks with a map of the country I describe [Plate
VI.], and with the specimens of different matters that compose the most
remarkable spots of it, I do not doubt but that I shall convince you, as
I am myself convinced, that the whole circuit (so far as I have
examined) within the boundaries marked in the map is wholly and totally
the production of subterraneous fires; and that most probably the sea
formerly reached the mountains that lie behind Capua and Caserta, and
are a continuation of the Appenines. If I may be allowed to compare
small things with great, I imagine the subterraneous fires to have
worked in this country, under the bottom of the sea, as moles in a
field, throwing up here and there a hillock; and that the matter thrown
out of some of these hillocks, formed into settled Volcanos, filling up
the space between one and the other, has composed this part of the
continent, and many of the islands adjoining.
From the observations I have made upon Mount Etna, Vesuvius, and its
neighbourhood, I dare say, that, after a careful examination, most
mountains, that are or have been Volcanos, would be found to owe their
existence to subterraneous fire; the direct reverse of what I find the
commonly received opinion.
Nature, though varied, is certainly in general uniform in her
operations; and I cannot conceive that two such considerable Volcanos as
Etna and Vesuvius should have been formed otherwise than every other
considerable Volcano of the known world. I do not wonder that so little
progress has been made in the improvement of natural history, and
particularly in that branch of it which regards the theory of earth;
Nature acts slowly, it is difficult to catch her in the fact. Those who
have made this subject their study have, without scruple, undertaken at
once to write the natural history of a whole province, or of an entire
continent; not reflecting, that the longest life of man scarcely
affords him time to give a perfect one of the smallest insect.
I am sensible of what I undertake in giving you, Sir, even a very
imperfect account of the nature of the soil of a little more than twenty
miles round Naples: yet I flatter myself that my remarks, such as they
are, may be of some use to any one hereafter, who may have leisure and
inclination to follow them up. The kingdom of the Two Sicilies offers
certainly the fairest field for observations of this kind, of any in the
whole world; here are Volcanos existing in their full force, some on
their decline, and others totally extinct.
To begin with some degree of order, which is really difficult in the
variety of matter that occurs to my mind, I will first mention the basis
on which I found all my conjectures. It is the nature of the soil that
covers the antient towns of Herculaneum and Pompeii, and the interior
and exterior form of the new mountain, near Puzzole, with the sort of
materials of which it is composed. It cannot be denied, that Herculaneum
and Pompeii stood once above ground; though now, the former is in no
part less than seventy feet, and in some parts one hundred and twelve
feet, below the present surface of the earth; and the latter is buried
ten or twelve feet deep, more or less. As we know from the very accurate
account given by Pliny the younger to Tacitus, and from the accounts of
other contemporary authors, that these towns were buried by an eruption
of Mount Vesuvius in the time of Titus; it must be allowed, that
whatever matter lies between these cities and the present surface of the
earth over them, must have been produced since the year 79 of the
Christian aera, the date of that formidable eruption.
Pompeii, which is situated at a much greater distance from the Volcano
than Herculaneum, has felt the effects of a single eruption only; it is
covered with white pumice stones, mixed with fragments of lava and
burnt matter, large and small: the pumice is very light; but I have
found some of the fragments of lava and cinders there, weighing eight
pounds. I have often wondered, that such weighty bodies could have been
carried to such a distance (for Pompeii cannot be less than five miles,
in a strait line, from the mouth of Vesuvius). Every observation
confirms the fall of this horrid shower over the unfortunate city of
Pompeii, and that few of its inhabitants had dared to venture out of
their houses; for in many of those which have been already cleared,
skeletons have been found, some with gold rings, ear rings, and
bracelets. I have been present at the discovery of several human
skeletons myself; and under a vaulted arch, about two years ago, at
Pompeii, I saw the bones of a man and a horse taken up, with the
fragments of the horse's furniture, which had been ornamented with false
gems set in bronze. The skulls of some of the skeletons found in the
streets had been evidently fractured by the fall of the stones. His
Sicilian Majesty's excavations are confined to this spot at present; and
the curious in antiquity may expect hereafter, from so rich a mine,
ample matter for their dissertations: but I will confine myself to such
observations only as relate to my present subject.