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OBSERVATIONS
ON
MOUNT VESUVIUS,
MOUNT ETNA,
AND OTHER VOLCANOS:
IN
A SERIES OF LETTERS,
Addressed to THE ROYAL SOCIETY,
From the Honourable Sir W. HAMILTON,
K.B. F.R.S.
His Majesty's Envoy Extraordinary and Plenipotentiary
at the Court of NAPLES.
To which are added,
Explanatory NOTES by the AUTHOR,
hitherto unpublished.
A NEW EDITION.
LONDON,
Printed for T. CADELL, in the Strand.
M DCC LXXIV.
THE EDITOR
TO
THE PUBLIC.
Having mentioned to Sir WILLIAM HAMILTON the general Desire of all
Lovers of Natural History, that his Letters upon the Subject of VOLCANOS
should be collected together in one Volume, particularly for the
Convenience of such as may have an Opportunity of visiting the curious
Spots described in them: He was not only pleased to approve of my
having undertaken this Publication, but has likewise favoured with the
additional explanatory Notes and Drawings,
The PUBLIC's most obliged,
and devoted
humble Servant,
T. CADELL.
May 30, 1772.
OBSERVATIONS
ON
MOUNT VESUVIUS, &c.
LETTER I.
To the Right Honourable the Earl of MORTON, President of the Royal
Society.
Naples, June 10, 1766.
My LORD,
As I have attended particularly to the various changes of Mount
Vesuvius, from the 17th of November 1764, the day of my arrival at this
capital; I flatter myself, that my observations will not be unacceptable
to your Lordship, especially as this Volcano has lately made a very
considerable eruption. I shall confine myself merely to the many
extraordinary appearances that have come under my own inspection, and
leave their explanation to the more learned in Natural Philosophy.
During the first twelvemonth of my being here, I did not perceive any
remarkable alteration in the mountain; but I observed, the smoke from
the Volcano was much more considerable in bad weather than when it was
fair[1]; and I often heard (even at Naples, six miles from Vesuvius) in
bad weather, the inward explosions of the mountain. When I have been at
the top of Mount Vesuvius in fair weather, I have sometimes found so
little smoke, that I have been able to see far down the mouth of the
Volcano; the sides of which were incrusted with salts and mineral of
various colors, white, green, deep and pale yellow. The smoke that
issued from the mouth of the Volcano in bad weather was white, very
moist, and not near so offensive as the sulphureous steams from various
cracks on the sides of the mountain.
Towards the month of September last, I perceived the smoke to be more
considerable, and to continue even in fair weather; and in October I
perceived sometimes a puff of black smoke shoot up a considerable height
in the midst of the white, which symptom of an approaching eruption grew
more frequent daily; and soon after, these puffs of smoke appeared in
the night tinged like clouds with the setting sun.
About the beginning of November, I went up the mountain: it was then
covered with snow; and I perceived a little hillock of sulphur had been
thrown up, since my last visit there, within about forty yards of the
mouth of the Volcano; it was near six feet high, and a light blue flame
issued constantly from its top. As I was examining this phaenomenon, I
heard a violent report; and saw a column of black smoke, followed by a
reddish flame, shoot up with violence from the mouth of the Volcano; and
presently fell a shower of stones, one of which, falling near me, made
me retire with some precipitation, and also rendered me more cautious of
approaching too near, in my subsequent journies to Vesuvius.
From November to the 28th of March, the date of the beginning of this
eruption, the smoke increased, and was mixed with ashes, which fell, and
did great damage to the vineyards in the neighbourhood of the
mountain[2]. A few days before the eruption I saw (what Pliny the
younger mentions having seen, before that eruption of Vesuvius which
proved fatal to his uncle) the black smoke take the form of a pine-tree.
The smoke, that appeared black in the day-time, for near two months
before the eruption, had the appearance of flame in the night.
On Good Friday, the 28th of March, at 7 o'clock at night, the lava began
to boil over the mouth of the Volcano, at first in one stream; and soon
after, dividing itself into two, it took its course towards Portici. It
was preceded by a violent explosion, which caused a partial earthquake
in the neighbourhood of the mountain; and a shower of red hot stones and
cinders were thrown up to a considerable height. Immediately upon sight
of the lava, I left Naples, with a party of my countrymen, whom I found
as impatient as myself to satisfy their curiosity in examining so
curious an operation of nature. I passed the whole night upon the
mountain; and observed that, though the red hot stones were thrown up in
much greater number and to a more considerable height than before the
appearance of the lava, yet the report was much less considerable than
some days before the eruption. The lava ran near a mile in an hour's
time, when the two branches joined in a hollow on the side of the
mountain, without proceeding farther. I approached the mouth of the
Volcano, as near as I could with prudence; the lava had the appearance
of a river of red hot and liquid metal, such as we see in the
glass-houses, on which were large floating cinders, half lighted, and
rolling one over another with great precipitation down the side of the
mountain, forming a most beautiful and uncommon cascade; the color of
the fire was much paler and more bright the first night than the
subsequent nights, when it became of a deep red, probably owing to its
having been more impregnated with sulphur at first than afterwards. In
the day-time, unless you are quite close, the lava has no appearance of
fire; but a thick white smoke marks its course.
The 29th, the mountain was very quiet, and the lava did not continue.
The 30th, it began to flow again in the same direction, whilst the mouth
of the Volcano threw up every minute a girandole of red hot stones, to
an immense height. The 31st, I passed the night upon the mountain: the
lava was not so considerable as the first night; but the red hot stones
were perfectly transparent, some of which, I dare say of a ton weight,
mounted at least two hundred feet perpendicular, and fell in, or near,
the mouth of a little mountain, that was now formed by the quantity of
ashes and stones, within the great mouth of the Volcano, and which made
the approach much safer than it had been some days before, when the
mouth was near half a mile in circumference, and the stones took every
direction. Mr. Hervey, brother to the Earl of Bristol, was very much
wounded in the arm some days before the eruption, having approached too
near; and two English gentlemen with him were also hurt. It is
impossible to describe the beautiful appearance of these girandoles of
red hot stones, far surpassing the most astonishing artificial
fire-work.
From the 31st of March to the 9th of April, the lava continued on the
same side of the mountain, in two, three, and sometimes four branches,
without descending much lower than the first night. I remarked a kind of
intermission in the fever of the mountain[3], which seemed to return
with violence every other night. On the 10th of April, at night, the
lava disappeared on the side of the mountain towards Naples, and broke
out with much more violence on the side next the _Torre dell'
Annunciata_.
I passed the whole day and the night of the twelfth upon the mountain,
and followed the course of the lava to its very source: it burst out of
the side of the mountain, within about half a mile of the mouth of the
Volcano, like a torrent, attended with violent explosions, which threw
up inflamed matter to a considerable height, the adjacent ground
quivering like the timbers of a water-mill; the heat of the lava was so
great, as not to suffer me to approach nearer than within ten feet of
the stream, and of such a consistency (though it appeared liquid as
water) as almost to resist the impression of a long stick, with which I
made the experiment; large stones thrown on it with all my force did not
sink, but, making a slight impression, floated on the surface, and were
carried out of sight in a short time; for, notwithstanding the
consistency of the lava, it ran with amazing velocity; I am sure, the
first mile with a rapidity equal to that of the river Severn, at the
passage near Bristol. The stream at its source was about ten feet wide,
but soon extended itself, and divided into three branches; so that these
rivers of fire, communicating their heat to the cinders of former lavas,
between one branch and the other, had the appearance at night of a
continued sheet of fire, four miles in length, and in some parts near
two in breadth. Your Lordship may imagine the glorious appearance of
this uncommon scene, such as passes all description.
The lava, after having run pure for about a hundred yards, began to
collect cinders, stones, &c.; and a scum was formed on its surface,
which in the day-time had the appearance of the river Thames, as I have
seen it after a hard frost and great fall of snow, when beginning to
thaw, carrying down vast masses of snow and ice. In two places the
liquid lava totally disappeared, and ran in a subterraneous passage for
some paces; then came out again pure, having left the scum behind. In
this manner it advanced to the cultivated parts of the mountain; and I
saw it, the same night of the 12th, unmercifully destroy a poor man's
vineyard, and surround his cottage, notwithstanding the opposition of
many images of St. Januarius, that were placed upon the cottage, and
tied to almost every vine. The lava, at the farthest extremity from its
source, did not appear liquid, but like a heap of red hot coals,
forming a wall in some places ten or twelve feet high, which rolling
from the top soon formed another wall, and so on, advancing slowly, not
more than about thirty feet in an hour[4].
The mouth of the Volcano has not thrown up any large stones since the
second eruption of lava on the 10th of April; but has thrown up
quantities of small ashes and pumice stones, that have greatly damaged
the neighbouring vineyards. I have been several times at the mountain
since the 12th; but, as the eruption was in its greatest vigour at that
time, I have ventured to dwell on, and I fear tire your Lordship with,
the observations of that day.
In my last visit to Mount Vesuvius, the 3d of June, I still found that
the lava continued; but the rivers were become rivulets, and had lost
much of their rapidity. The quantity of matter thrown out by this
eruption is greater than that of the last in the year 1760; but the
damage to the cultivated lands is not so considerable, owing to its
having spread itself much more, and its source being at least three
miles higher up. This eruption seems now to have exhausted itself; and I
expect in a few days to see Vesuvius restored to its former
tranquillity.
Mount Etna in Sicily broke out on the 27th of April; and made a lava, in
two branches, at least six miles in length, and a mile in breadth; and,
according to the description given me by Mr. Wilbraham, (who was there,
after having seen with me part of the eruption of Mount Vesuvius)
resembles it in every respect, except that Mount Etna, at the place from
whence the lava flowed (which was twelve miles from the mouth of the
Volcano), threw up a fountain of liquid inflamed matter to a
considerable height; which, I am told, Mount Vesuvius has done in former
eruptions.
I beg pardon for having taken up so much of your time; and yet I flatter
myself, that my description, which I assure your Lordship is not
exaggerated, will have afforded you some amusement. I have the honour to
be,
My LORD,
Your Lordship's
Most obedient
and most humble servant,
WILLIAM HAMILTON.
* * * * *
Naples, February 3, 1767.
Since the account of the eruption of Mount Vesuvius, which I had the
honour of giving to your Lordship, in my letter of the 10th of June
last; I have only to add, that the lava continued till about the end of
November, without doing any great damage, having taken its course over
antient lavas. Since the cessation of this eruption, I have examined
the crater, and the crack on the side of the mountain towards _Torre
dell' Annunciata_, about a hundred yards from the crater from whence
this lava issued: and I found therein some very curious salts and
sulphurs; a specimen of each sort I have put into bottles myself, even
upon the mountain, that they might not lose any of their force, and have
sent them in a box directed to your Lordship, as you will see, by the
bill of lading: I am sure, you will have a pleasure in seeing them
analyzed[5]. I have also packed in the same box some lava, and cinders,
of the last eruption; there is one piece in particular very curious,
having the exact appearance of a cable petrified. I shall be very happy
if these trifles should afford your Lordship a moment's amusement.
It is very extraordinary, that I cannot find, that any chemist here has
ever been at the trouble of analyzing the productions of Vesuvius.
The deep yellow, or orange-color salts, of which there are two bottles,
I fetched out of the very crater of the mountain, in a crevice that was
indeed very hot. It seems to me to be powerful, as it turns silver black
in an instant, but has no effect upon gold. If your Lordship pleases, I
will send you by another opportunity specimens of the sulphurs and salts
of the Solfa terra, which seem to be very different from these.
Within these three days, the fire has appeared again on the top of
Vesuvius, and earthquakes have been felt in the neighbourhood of the
mountain. I was there on Saturday with my nephew Lord Greville; we heard
most dreadful inward grumblings, rattling of stones, and hissing; and
were obliged to leave the crater very soon, on account of the emission
of stones. The black smoak arose, as before the last eruption; and I saw
every symptom of a new eruption, of which I shall not fail to give your
Lordship an exact account.
LETTER II.
To the Right Honourable the Earl of MORTON, President of the Royal
Society.
Naples, December 29, 1767.
My LORD,
The favourable reception, which my account of last year's eruption of
Mount Vesuvius met with from your Lordship; the approbation which the
Royal Society was pleased to shew, by having ordered the same to be
printed in their Philosophical Transactions; and your Lordship's
commands, in your letter of the 3d instant; encourage me to trouble you
with a plain narrative of what came immediately under my observation,
during the late violent eruption, which began October 19, 1767, and is
reckoned to be the twenty-seventh since that, which, in the time of
Titus, destroyed Herculaneum and Pompeii.
The eruption of 1766 continued in some degree till the 10th of December,
about nine months in all[6]; yet in that space of time the mountain did
not cast up a third of the quantity of lava, which it disgorged in only
seven days, the term of this last eruption. On the 15th of December,
last year, within the ancient crater of Mount Vesuvius, and about twenty
feet deep, there was a crust, which formed a plain, not unlike the
Solfa terra in miniature; in the midst of this plain was a little
mountain, whose top did not rise so high as the rim of the ancient
crater. I went into this plain, and up the little mountain, which was
perforated, and served as the principal chimney to the Volcano: when I
threw down large stones, I could hear that they met with many
obstructions in their way, and could count a hundred moderately before
they reached the bottom.
Vesuvius was quiet till March 1767, when it began to throw up stones
from time to time; in April, the throws were more frequent, and at night
fire was visible on top of the mountain, or, more properly speaking, the
smoak, which hung over the crater, was tinged by the reflection of the
fire within the Volcano. These repeated throws of cinders, ashes, and
pumice stones, increased the little mountain so much, that in May the
top was visible above the rim of the ancient crater. The 7th of August,
there issued a small stream of lava, from a breach in the side of this
little mountain, which gradually filled the valley between it and the
ancient crater; so that, the 12th of September, the lava overflowed the
ancient crater, and took its course down the sides of the great
mountain; by this time, the throws were much more frequent, and the red
hot stones went so high as to take up ten seconds in their fall. Padre
Torre, a great observer of Mount Vesuvius, says they went up above a
thousand feet.
The 15th of October, the height of the little mountain (formed in about
eight months) was measured by Don Andrea Pigonati, a very ingenious
young man, in his Sicilian Majesty's service, who assured me that its
height was 185 French feet.
From my villa, situated between Herculaneum and Pompeii, near the
convent of the Calmaldolese (marked 7 in Plate I.) I had watched the
growing of this little mountain; and, by taking drawings of it from
time to time, I could perceive its increase most minutely. I make no
doubt but that the whole of Mount Vesuvius has been formed in the same
manner; and as these observations seem to me to account for the various
irregular strata, which are met with in the neighbourhood of Volcanos, I
have ventured to inclose, for your Lordship's inspection, a copy of the
abovementioned drawings. (Plate III.)
The lava continued to run over the ancient crater in small streams,
sometimes on one side, and sometimes on another, till the 18th of
October, when I took particular notice that there was not the least lava
to be seen; owing, I imagine, to its being employed in forcing its way
towards the place where it burst out the following day. As I had,
contrary to the opinion of most people here, foretold the approaching
eruption[7], and had observed a great fermentation in the mountain
after the heavy rains which fell the 13th and 14th of October; I was not
surprized, on the 19th following, at seven of the clock in the morning,
to perceive from my villa every symptom of the eruption being just at
hand. From the top of the little mountain issued a thick black smoak, so
thick that it seemed to have difficulty in forcing its way out; cloud
after cloud mounted with a hasty spiral motion, and every minute a
volley of great stones were shot up to an immense height in the midst of
these clouds; by degrees, the smoak took the exact shape of a huge
pine-tree, such as Pliny the younger described in his letter to Tacitus,
where he gives an account of the fatal eruption in which his uncle
perished[8]. This column of black smoak, after having mounted an
extraordinary height, bent with the wind towards Caprea, and actually
reached over that island, which is not less than twenty-eight miles from
Vesuvius.
I warned my family, not to be alarmed, as I expected there would be an
earthquake at the moment of the lava's bursting out; but before eight of
the clock in the morning I perceived that the mountain had opened a
mouth, without noise, about a hundred yards lower than the ancient
crater, on the side towards the Monte di Somma; and I plainly perceived,
by a white smoak, which always accompanies the lava, that it had forced
its way out: as soon as it had vent, the smoak no longer came out with
that violence from the top. As I imagined that there would be no danger
in approaching the mountain when the lava had vent, I went up
immediately, accompanied by one peasant only. I passed the hermitage (3.
in Plate I.), and proceeded as far as the spot marked (X), in the valley
between the mountain of Somma and that of Vesuvius, which is called
Atrio di Cavallo. I was making my observations upon the lava, which had
already, from the spot (E) where it first broke out, reached the valley;
when, on a sudden, about noon, I heard a violent noise within the
mountain, and at the spot (C), about a quarter of a mile off the place
where I stood, the mountain split; and, with much noise, from this new
mouth, a fountain of liquid fire shot up many feet high, and then, like
a torrent, rolled on directly towards us. The earth shook, at the same
time that a volley of pumice stones fell thick upon us; in an instant,
clouds of black smoak and ashes caused almost a total darkness; the
explosions from the top of the mountain were much louder than any
thunder I ever heard, and the smell of the sulphur was very offensive.
My guide, alarmed, took to his heels; and I must confess, that I was not
at my ease. I followed close, and we ran near three miles without
stopping; as the earth continued to shake under our feet, I was
apprehensive of the opening of a fresh mouth, which might have cut off
our retreat. I also feared that the violent explosions would detach some
of the rocks off the mountain Somma, under which we were obliged to
pass; besides, the pumice-stones, falling upon us like hail, were of
such a size as to cause a disagreeable sensation upon the part where
they fell. After having taken breath, as the earth still trembled
greatly, I thought it most prudent to leave the mountain, and return to
my villa; where I found my family in a great alarm, at the continual and
violent explosions of the Volcano, which shook our house to its very
foundation, the doors and windows swinging upon their hinges. About two
of the clock in the afternoon another lava forced its way out of the
same place from whence came the lava last year, at the spot marked B (in
Plate II.); so that the conflagration was soon as great on this side of
the mountain, as on the other which I had just left.
The noise and smell of sulphur increasing, we removed from our villa to
Naples; and I thought proper, as I passed by Portici, to inform the
Court of what I had seen; and humbly offered it as my opinion, that his
Sicilian Majesty should leave the neighbourhood of the threatening
mountain. However, the Court did not leave Portici till about twelve of
the clock, when the lava had reached as far as (4. in Plate I.)--I
observed, in my way to Naples, which was in less than two hours after I
had left the mountain, that the lava had actually covered three miles of
the very road through which we had retreated. It is astonishing that it
should have run so fast; as I have since seen, that the river of lava,
in the Atrio di Cavallo, was sixty and seventy feet deep, and in some
places near two miles broad. When his Sicilian Majesty quitted Portici,
the noise was greatly increased; and the concussion of the air from the
explosions was so violent, that, in the King's palace, doors and windows
were forced open; and even one door there, which was locked, was
nevertheless burst open. At Naples, the same night, many windows and
doors flew open; in my house, which is not on the side of the town next
Vesuvius, I tried the experiment of unbolting my windows[9], when they
flew wide open upon every explosion of the mountain. Besides these
explosions, which were very frequent, there was a continued
subterraneous and violent rumbling noise, which lasted this night about
five hours. I have imagined, that this extraordinary noise might be
owing to the lava in the bowels of the mountain having met with a
deposition of rain water; and that the conflict between the fire and the
water may, in some measure, account for so extraordinary a crackling and
hissing noise. Padre Torre, who has wrote so much and so well upon the
subject of Mount Vesuvius, is also of my opinion. And indeed it is
natural to imagine, that there may be rain-water lodged in many of the
caverns of the mountain; as, in the great eruption of Mount Vesuvius in
1631, it is well attested, that several towns, among which Portici and
Torre del Greco, were destroyed, by a torrent of boiling water having
burst out of the mountain with the lava, by which thousands of lives
were lost. About four years ago, Mount Etna in Sicily threw up hot water
also, during an eruption.
The confusion at Naples this night cannot be described; his Sicilian
Majesty's hasty retreat from Portici added to the alarm; all the
churches were opened and filled; the streets were thronged with
processions of saints: but I shall avoid entering upon a description of
the various ceremonies that were performed in this capital, to quell the
fury of the turbulent mountain.
Tuesday the 20th, it was impossible to judge of the situation of
Vesuvius, on account of the smoak and ashes, which covered it entirely,
and spread over Naples also, the sun appearing as through a thick London
fog, or a smoaked glass; small ashes fell all this day at Naples. The
lavas on both sides of the mountain ran violently; but there was little
or no noise till about nine o'clock at night, when the same uncommon
rumbling began again, accompanied with explosions as before, which
lasted about four hours: it seemed as if the mountain would split in
pieces; and, indeed, it opened this night almost from the spot E to C
(in Plate I.). The annexed plans were taken upon the spot at this time,
when the lavas were at their height; and I do not think them
exaggerated. The Parisian barometer was, as yesterday, at 279, and
Fahrenheit's thermometer at 70 degrees; whereas, for some days preceding
the eruption, it had been at 65 and 66. During the confusion of this
night, the prisoners in the public jail attempted to escape, having
wounded the jailer; but were prevented by the troops. The mob also set
fire to the Cardinal Archbishop's gate, because he refused to bring out
the relicks of Saint Januarius.
Wednesday 21st, was more quiet than the preceding days, though the lavas
ran briskly. Portici was once in some danger, had not the lava taken a
different course when it was only a mile and a half from it; towards
night, the lava slackened.
Thursday 22d, about ten of the clock in the morning, the same thundering
noise began again, but with more violence than the preceding days; the
oldest men declared, they had never heard the like; and, indeed, it was
very alarming: we were in expectation every moment of some dire
calamity. The ashes, or rather small cinders, showered down so fast,
that the people in the streets were obliged to use umbrellas, or flap
their hats; these ashes being very offensive to the eyes. The tops of
the houses, and the balconies, were covered above an inch thick with
these cinders[10]. Ships at sea, twenty leagues from Naples, were also
covered with them, to the great astonishment of the sailors. In the
midst of these horrors, the mob, growing tumultuous and impatient,
obliged the Cardinal to bring out the head of Saint Januarius, and go
with it in procession to the Ponte Maddalena, at the extremity of
Naples, towards Vesuvius; and it is well attested here, that the
eruption ceased the moment the Saint came in sight of the mountain; it
is true, the noise ceased about that time, after having lasted five
hours, as it had done the preceding days.
Friday 23d, the lavas still ran, and the mountain continued to throw up
quantities of stones from its crater; there was no noise heard at Naples
this day, and but little ashes fell there.
Saturday 24th, the lava ceased running; the extent of the lava, from
the spot C (Plate I.), where I saw it break out, to its extremity F,
where it surrounded the chapel of Saint Vito, is above six miles. In the
Atrio di Cavallo, and in a deep valley that lies between Vesuvius (1.)
and the hermitage (3.), the lava is in some places near two miles broad,
and in most places from sixty to seventy feet deep; at (4.), the lava
ran down a hollow way, called Fossa grande, made by the currents of rain
water; it is not less than two hundred feet deep, and a hundred broad;
yet the lava in one place has filled it up. I could not have believed
that so great a quantity of matter could have been thrown out in so
short a time, if I had not since examined the whole course of the lava
myself. This great compact body will certainly retain some heat many
months[11]; at this time, much rain having fallen for some days past,
the lava smoaks, as if it ran afresh: and about ten days ago, when I was
up the mountain with Lord Stormont, we thrust sticks into the crevices
of the lava, which took fire immediately: But to proceed with my
journal.
The 24th, Vesuvius continued to throw up stones as on the preceding
days: during the whole of this eruption, it had differed in this
circumstance from the eruption of 1766, when no stones were thrown out
of the crater from the moment the lava ran freely.
Sunday 25th, small ashes fell all day at Naples; they issued from the
crater of the Volcano, and formed a vast column, as black as the
mountain itself, so that the shadow of it was marked out on the surface
of the sea; continual flashes of forked or zig-zag lightning shot from
this black column, the thunder of which was heard in the neighbourhood
of the mountain, but not at Naples: there were no clouds in the sky at
this time, except those of smoak issuing from the crater of Vesuvius. I
was much pleased with this phaenomenon, which I had not seen before in
that perfection[12].
Monday 26th, the smoak continued, but not so thick, neither were there
any flashes of the mountain lightning. As no lava has appeared after
this column of black smoak, which must have been occasioned by some
inward operation of fire; I am apt to think, that the lava, which should
naturally have followed this symptom, has broke its way into some deeper
cavern, where it is silently brooding future mischief; and I shall be
much mistaken if it does not break out a few months hence.
Tuesday 27th, no more black smoak, nor any signs of eruption.
Thus, my Lord, I have had the honor of giving your Lordship a faithful
narrative of my observations during this eruption, which is universally
allowed to have been the most violent of this century; and I shall be
happy, if it should meet with your approbation, and that of the Royal
Society, if your Lordship should think it worthy of being communicated
to so respectable a body.
I have just sent a present to the British Museum of a complete
collection of every sort of matter produced by Mount Vesuvius, which I
have been collecting with some pains for these three years past; and it
will be a great satisfaction to me, if, by the means of this collection,
some of my countrymen, learned in natural history, may be enabled to
make some useful discoveries relative to Volcanos[13].
I have also accompanied that collection with a view of a current of
lava from Mount Vesuvius; it is painted with transparent colours, and,
when lighted up with lamps behind it, gives a much better idea of
Vesuvius, than is possible to be given by any other sort of painting.
I have the honor to be,
My LORD,
Your Lordship's
Most obedient
and most humble servant,
WILLIAM HAMILTON.
[Illustration: _Plate I._
View of the GREAT ERUPTION of VESUVIUS 1767 from Portici.]
PLATE I.
A. Crater of Mount Vesuvius.
B. Mouth from whence came the lava of 1766; and which opened
afresh, October 19, 1767, and produced the conflagration
represented in Plate II.
C. The mouth which opened at 12 o'clock, October 19, 1767, whilst
I was at the spot marked X; from thence came all the lava
represented in Plate I.
D. The lava.
E. Mouth from whence the lava flowed at eight o'clock, October 19,
when the eruption began first.
F. Chapel of Saint Vito, surrounded with lava.
1. Vesuvius.
2. Mountain of Somma.
3. Hermitage, between which and Vesuvius there is a deep valley
two miles broad.
4. The Fossa Grande.
5. His Sicilian Majesty's Palace at Portici.
6. Church of Pugliano.
7. Calmaldolese Convent, near which is my Villa.
8. Saint Jorio.
9. Barra.
10. Spot, under which lies Herculaneum.
[Illustration: _Plate II._
View of the GREAT ERUPTION of VESUVIUS 1767, from Torre dell'
Annunziata.]
PLATE II.
A. Crater of Vesuvius.
B. Mouth, from whence came the lava of 1766, and which opened
afresh at two o'clock, October 19, 1767, and caused the
conflagration on this side of the mountain.
C. Mouth which opened at 12 o'clock, October 19, 1767, whilst I
was at the spot X, and which produced all the lava
represented in Plate I.
D. Rivulets of lava, which flowed from the crater, and united with
the great river E.
F. Extremities of the lava, about five miles from B.
1. Mountain of Somma.
2. Mount Vesuvius.
3. Montagna di Trecase.
4. Trecase.
5. Oratorio di Bosco.
6. Ottaiano.
[Illustration: _Plate III._
_The ancient Crater of Mount Vesuvius._
_With the gradual increase of the little Mountain within the Crater._
_The exteriour black line marks each increase & the interiour dotted
line shews the state of the little Mountain before that increase, so
that the dotted line in the Drawing of Oct 18.^{th} shews the Size of
the little Mountain July 8.^{th} the little spot A. marks where the lava
came out some days before the great Eruption. B. C. D. mark the ancient
Crater & E. the little Mountain the day before the Eruption. F. G. is
the present Crater, & the exteriour black line H. F. G. the present
shape of the top of Mount Vesuvius. Since May last the Mountain is
increased from B. to F. which is near 200 feet._]
PLATE III.
Views of the gradual increase of the little mountain within the
ancient crater; and of the present shape of Mount Vesuvius.
LETTER III.
To MATHEW MATY, M. D. Secretary to the Royal SOCIETY.
Villa Angelica, near Mount Vesuvius,
October 4, 1768.
SIR,
I have but very lately received your last obliging letter, of the 5th of
July, with the volume of Philosophical Transactions.
I must beg of you to express my satisfaction at the notice which the
Royal Society hath been pleased to take of my accounts of the two last
eruptions of Mount Vesuvius. Since I have been at my villa here, I have
enquired of the inhabitants of the mountain, after what they had seen
during the last eruption. In my letter to Lord Morton, I mentioned
nothing but what came immediately under my own observation: but as all
the peasants here agree in their account of the terrible thunder and
lightning, which lasted almost the whole time of the eruption, upon the
mountain only; I think it a circumstance worth attending to. Besides the
lightning, which perfectly resembled the common forked lightning, there
were many meteors, like what are vulgarly called _falling stars_. A
peasant, in my neighbourhood, lost eight hogs, by the ashes falling into
the trough with their food: they grew giddy, and died in a few hours.
The last day of the eruption, the ashes, which fell abundantly upon the
mountain, were as white almost as snow[14]; and the old people here
assure me, that is a sure symptom of the eruption being at an end.
These circumstances, being well attested, I thought worth relating.
It would require many years close application, to give a proper and
truly philosophical account of the Volcanos in the neighbourhood of
Naples; but I am sure such a history might be given, supported by
demonstration, as would destroy every system hitherto given upon this
subject. We have here an opportunity of seeing Volcanos in all their
states. I have been this summer in the island of Ischia; it is about
eighteen miles round, and its whole basis is lava. The great mountain in
it, near as high as Vesuvius, formerly called Epomeus, and now San
Nicolo, I am convinced, was thrown up by degrees; and I have no doubt
in my own mind, but that the island itself rose out of the sea in the
same manner as some of the Azores. I am of the same opinion with respect
to Mount Vesuvius, and all the high grounds near Naples; as having not
yet seen, in any one place, what can be called virgin earth. I had the
pleasure of seeing a well sunk, a few days ago, near my villa, which is,
as you know, at the foot of Vesuvius, and close by the sea-side. At
twenty-five feet below the level of the sea, they came to a stratum of
lava, and God knows how much deeper they might have still found other
lavas. The soil all round the mountain, which is so fertile, consists of
stratas of lavas, ashes, pumice, and now-and-then a thin stratum of good
earth, which good earth is produced by the surface mouldering, and the
rotting of the roots of plants, vines, &c. This is plainly to be seen at
Pompeii, where they are now digging into the ruins of that ancient city;
the houses are covered about ten or fifteen feet, with pumice and
fragments of lava, some of which weigh three pounds (which last
circumstance I mention, to shew, that, in a great eruption, Vesuvius has
thrown stones of this weight six miles[15], which is its distance from
Pompeii, in a direct line); upon this stratum of pumice, or _rapilli_,
as they call them here, is a stratum of excellent mould, about two feet
thick, on which grow large trees, and excellent grapes. We have then the
Solfaterra, which was certainly a Volcano, and has ceased erupting, for
want of metallic particles, and over-abounding with sulphur. You may
trace its lavas into the sea. We have the Lago d'Averno and the Lago
d'Agnano, both of which were formerly Volcanos; and Astroni, which still
retains its form more than any of these. Its crater is walled round, and
his Sicilian Majesty takes the diversion of boar-hunting in this
Volcano; and neither his Majesty nor any one of his Court ever dreamt of
its former state. We have then that curious mountain, called Montagno
Nuovo, near Puzzole, which rose, in one night, out of the Lucrine Lake;
it is about a hundred and fifty feet high, and three miles round. I do
not think it more extraordinary, that Mount Vesuvius, in many ages,
should rise above two thousand feet; when this mountain, as is well
attested, rose in one night, no longer ago than the year 1538. I have a
project, next spring, of passing some days at Puzzole, and of dissecting
this mountain, taking its measures, and making drawings of its stratas;
for, I perceive, it is composed of stratas, like Mount Vesuvius, but
without lavas. As this mountain is so undoubtedly formed intirely from a
plain, I should think my project may give light into the formation of
many other mountains, that are at present thought to have been original,
and are certainly not so, if their strata correspond with those of the
Montagno Nuovo. I should be glad to know whether you think this project
of mine will be useful; and, if you do, the result of my observations
may be the subject of another letter[16].
I cannot have a greater pleasure than to employ my leisure hours in what
may be of some little use to mankind; and my lot has carried me into a
country, which affords an ample field for observation. Upon the whole,
if I was to establish a system, it would be, that _Mountains are
produced by Volcanos, and not Volcanos by Mountains_.
I fear I have tired you; but the subject of Volcanos is so favourite a
one with me, that it has led me on I know not how: I shall only add,
that Vesuvius is quiet at present, though very hot at top, where there
is a deposition of boiling sulphur. The lava that ran in the Fossa
Grande during the last eruption, and is at least two hundred feet thick,
is not yet cool; a stick, put into its crevices, takes fire immediately.
On the sides of the crevices are fine crystalline salts: as they are the
pure salts, which exhale from the lava that has no communication with
the interiour of the mountain, they may perhaps indicate the composition
of the lava.
I have done. Let me only thank you for the kind offers and expressions
in your letter, and for the care you have had in setting off my present
to the Museum to the best advantage; of which I have been told from many
quarters.
I am,
SIR,
Your most obedient
humble servant,
W. HAMILTON.
LETTER IV.
To MATHEW MATY, M. D. Secretary to the Royal SOCIETY.
An Account of a Journey to MOUNT ETNA.
"Artificis naturae ingens opus aspice, nulla
"Tu tanta humanis rebus spectacula cernes."
P. CORNELII SEVERI _AEtna_.
Naples, Oct. 17, 1769.
SIR,
Encouraged by the assurances you give me, in your last obliging letter
of the 15th of June, that any new communication upon the subject of
Volcano's would be received with satisfaction by the Royal Society; I
venture to send you the following account of my late observations upon
Mount Etna, which you are at liberty to lay before our respectable
Society, should you think it worth its notice. [See Plate IV.]
[Illustration: _Plate IV._
A View of MOUNT AETNA from Taormina.]
After having examined with much attention the operations of Mount
Vesuvius, during the five years that I have had the honour of residing
as his Majesty's Minister at this Court, and after having carefully
remarked the nature of the soil for fifteen miles round this capital; I
am, in my own mind, well convinced that the whole of it has been formed
by explosion. Many of the craters, from whence this matter has issued,
are still visible; such as the Solfaterra near Puzzole, the lake of
Agnano, and near this lake a mountain composed of burnt matter, that has
a very large crater surrounded with a wall, to inclose the wild boars
and deer, that are kept there for the diversion of his Sicilian Majesty;
it is called Astruni: the Monte Nuovo, thrown up from the bottom of the
Lucrine lake[17] in the year 1538, which has likewise its crater; and
the lake of Averno. The islands of Nisida and Procida are entirely
composed of burnt matter; the island of Ischia is likewise composed of
lava, pumice, and burnt matter; and there are in that island several
visible craters, from one of which, no longer ago than the year 1303,
there issued a lava, which ran into the sea, and is still in the same
barren state as the modern lavas of Vesuvius. After having, I say, been
accustomed to these observations, I was well prepared to visit the most
ancient, and perhaps the most considerable, Volcano that exists; and I
had the satisfaction of being thoroughly convinced there, of the
formation of very considerable mountains by meer explosion, having seen
many such on the sides of Etna, as will be related hereafter.
On the 24th of June last, in the afternoon, I left Catania, a town
situated at the foot of Mount Etna, or, as it is now called,
Mon-Gibello, in company with Lord Fortrose and the Canonico Recupero, an
ingenious priest of Catania, who is the only person there that is
acquainted with the mountain: he is actually employed in writing its
natural history; but, I fear, will not be able to compass so great and
useful an undertaking, for want of proper encouragement.
We passed through the inferior district of the mountain, called by its
inhabitants La Regione Piemontese. It is well watered, exceedingly
fertile, and abounding with vines and other fruit trees, where the lava,
or, as it is called there, the _sciara_, has had time to soften, and
gather soil sufficient for vegetation, which, I am convinced from many
observations, unless assisted by art, does not come to pass for many
ages[18], perhaps a thousand years or more; the circuit of this lower
region, forming the basis of the great Volcano, is upwards of one
hundred Italian miles. The vines of Etna are kept low, quite the reverse
of those on the borders of Vesuvius; and they produce a stronger wine,
but not in so great abundance. The Piemontese district is covered with
towns, villages, monasteries, &c. and is well peopled, notwithstanding
the danger of such a situation. Catania, so often destroyed by eruptions
of Etna, and totally overthrown by an earthquake towards the end of the
last century[19], has been re-built within these fifty years, and is now
a considerable town, with at least thirty-five thousand inhabitants. I
do not wonder at the seeming security with which these parts are
inhabited, having been so long witness to the same near Mount Vesuvius.
The operations of Nature are slow: great eruptions do not frequently
happen; each flatters himself it will not happen in his time, or, if it
should, that his tutelar saint will turn away the destructive lava from
his grounds; and indeed the great fertility in the neighbourhoods of
Volcanos tempts people to inhabit them.
In about four hours of gradual ascent, we arrived at a little convent of
Benedictine monks, called St. Nicolo dell' Arena, about thirteen miles
from Catania, and within a mile of the Volcano from whence issued the
last very great eruption in the year 1669; a circumstantial account of
which was sent to our court by a Lord Winchelsea, who happened to be
then at Catania in his way home, from his embassy at Constantinople. His
Lordship's account is curious, and was printed in London soon after; I
saw a copy of it at Palermo, in the library of the Prince
Torremuzzo[20]. We slept in the Benedictines convent the night of the
24th, and passed the next morning in observing the ravage made by the
abovementioned terrible eruption, over the rich country of the
Piemontese. The lava burst out of a vineyard within a mile of St.
Nicolo, and, by frequent explosions of stones and ashes, raised there a
mountain, which, as near as I can judge, having ascended it, is not less
than half a mile perpendicular in height, and is certainly at least
three miles in circumference at its basis. The lava that ran from it,
and on which there are as yet no signs of vegetation, is fourteen miles
in length, and in many parts six in breadth; it reached Catania, and
destroyed part of its walls, buried an amphitheatre, an aqueduct, and
many other monuments of its ancient grandeur, which till then had
resisted the hand of Time, and ran a considerable length into the sea,
so as to have once formed a beautiful and safe harbour; but it was soon
after filled up by a fresh torrent of the same inflamed matter: a
circumstance the Catanians lament to this day, as they are without a
port. There has been no such eruption since, though there are signs of
many, more terrible, that have preceded it.
For two or three miles round the mountain raised by this eruption, all
is barren, and covered with ashes; this ground, as well as the mountain
itself, will in time certainly be as fertile as many other mountains in
its neighbourhood, that have been likewise formed by explosion. If the
dates of these explosions could be ascertained, it would be very
curious, and mark the progress of time with respect to the return of
vegetation, as the mountains raised by them are in different states;
those which I imagine to be the most modern are covered with ashes only;
others of an older date, with small plants and herbs; and the most
ancient, with the largest timber-trees I ever saw: but I believe the
latter are so very ancient, as to be far out of the reach of history. At
the foot of the mountain, raised by the eruption of the year 1669, there
is a hole, through which, by means of a rope, we descended into several
subterraneous caverns, branching out and extending much farther and
deeper than we chose to venture; the cold there being excessive, and a
violent wind frequently extinguishing some of our torches. These caverns
undoubtedly contained the lava that issued forth, and extended, as I
said before, quite to Catania. There are many of these subterraneous
cavities known, on other parts of Etna; such as that called by the
peasants La Baracca Vecchia, another La Spelonca della Palomba (from the
wild pigeons building their nests therein), and the cavern Thalia,
mentioned by Boccaccio. Some of them are made use of as magazines for
snow; the whole island of Sicily and Malta being supplied with this
essential article (in a hot climate) from Mount Etna. Many more would be
found, I dare say, if searched for, particularly near and under the
craters from whence great lavas have issued, as the immense quantities
of such matter we see above ground, must necessarily suppose very great
hollows underneath.