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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hitherto unpublished.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 phænomenon, 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 phænomenon, 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 naturæ ingens opus aspice, nulla
    "Tu tanta humanis rebus spectacula cernes."

                              P. CORNELII SEVERI _Ætna_.


                              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 ÆTNA 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.

After having passed the morning of the 25th in these observations, we
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 phænomenon
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 phænomenon; for Seneca (lib. ii. Nat. Quæst.) says,--"Ætna
aliquando multo igne abundavit, ingentem vim arenæ 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 æra, 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.

Over the stratum of pumice and burnt matter that covers Pompeii, there
is a stratum of good mould, of the thickness of about two feet and more
in some parts, in which vines flourish, except in some particular spots
of this vineyard, where they are subject to be blasted by a foul vapour,
or _mofete_, as it is called here, that rises from beneath the burnt
matter. The abovementioned shower of pumice stones, according to my
observations, extended beyond Castel-a-mare (near which spot the ancient
town of Stabia also lies buried under them) and covered a tract of
country not less than thirty miles in circumference. It was at Stabia
that Pliny the elder lost his life, and this shower of pumice stones is
well described in the younger Pliny's letter. Little of the matter that
has issued from Vesuvius since that time, has reached these parts: but I
must observe, that the pavement of the streets of Pompeii is of lava;
nay, under the foundation of the town, there is a deep stratum of lava
and burnt matter. These circumstances, with many others that will be
related hereafter, prove, beyond a doubt, that there have been eruptions
of Vesuvius previous to that of the year 79, which is the first recorded
by history.

The growth of soil by time is easily accounted for; and who, that has
visited ruins of ancient edifices, has not often seen a flourishing
shrub, in a good soil, upon the top of an old wall? I have remarked many
such on the most considerable ruins at Rome and elsewhere. But from the
soil which has grown over the barren pumice that covers Pompeii, I was
enabled to make a curious observation. Upon examining the cuts and
hollow ways made by currents of water in the neighbourhood of Vesuvius
and of other Volcanos, I had remarked that there lay frequently a
stratum of rich soil, of more or less depth, between the matter produced
by the explosion of succeeding eruptions[28]; and I was naturally led to
think, that such a stratum had grown in the same manner as the one
abovementioned over the pumice of Pompeii. Where the stratum of good
soil was thick, it was evident to me that many years had elapsed between
one eruption and that which succeeded it. I do not pretend to say, that
a just estimate can be formed of the great age of Volcanos from this
observation; but some sort of calculation might be made: for instance,
should an explosion of pumice cover again the spot under which Pompeii
is buried, the stratum of rich soil abovementioned would certainly lie
between two beds of pumice; and if a like accident had happened a
thousand years ago, the stratum of rich soil would as certainly have
wanted much of its present thickness, as the rotting of vegetables,
manure, &c. is ever increasing a cultivated soil. Whenever I find then a
succession of different strata of pumice and burnt matter, like that
which covers Pompeii, intermixed with strata of rich soil, of greater or
less depth, I hope I may be allowed reasonably to conclude, that the
whole has been the production of a long series of eruptions, occasioned
by subterraneous fire. By the size and weight of the pumice, and
fragments of burnt erupted matter in these strata, it is easy to trace
them up to their source, which I have done more than once in the
neighbourhood of Puzzole, where explosions have been frequent. The
gradual decrease in the size and quantity of the erupted matter in the
stratum abovementioned, from Pompeii to Castle-a-Mare, is very visible:
at Pompeii, as I said before, I have found them of eight pounds weight,
when at Castle-a-Mare the largest do not weigh an ounce.

The matter which covers the ancient town of Herculaneum is not the
produce of one eruption only; for there are evident marks that the
matter of six eruptions has taken its course over that which lies
immediately above the town, and was the cause of its destruction. These
strata are either of lava or burnt matter, with veins of good soil
between them. The stratum of erupted matter that immediately covers the
town, and with which the theatre and most of the houses were filled, is
not of that foul vitrified matter, called lava, but of a sort of soft
stone, composed of pumice, ashes, and burnt matter. It is exactly of
the same nature with what is called here the Naples stone; the Italians
distinguish it by the name of _tufa_, and it is in general use for
building. Its colour is usually that of our free stone, but sometimes
tinged with grey, green, and yellow; and the pumice stones, with which
it ever abounds, are sometimes large, and sometimes small: it varies
likewise in its degree of solidity.

The chief article in the composition of _tufa_ seems to me to be, that
fine burnt material, which is called _puzzolane_, whose binding quality
and utility by way of cement are mentioned by Vitruvius[29], and which
is to be met with only in countries that have been subject to
subterraneous fires. It is, I believe, a sort of lime prepared by
nature. This, mixed with water, great or small pumice stones, fragments
of lava, and burnt matter, may naturally be supposed to harden into a
stone of this kind[30]; and, as water frequently attends eruptions of
fire, as will be seen in the accounts I shall give of the formation of
the new mountain near Puzzole, I am convinced the first matter that
issued from Vesuvius, and covered Herculaneum, was in the state of
liquid mud. A circumstance strongly favouring my opinion is, that, about
two years ago, I saw the head of an antique statue dug out of this
matter within the theatre of Herculaneum; the impression of its face
remains to this day in the _tufa_, and might serve as a mould for a cast
in plaister of Paris, being as perfect as any mould I ever saw. As much
may be inferred from the exact resemblance of this matter, or _tufa_,
which immediately covers Herculaneum, to all the _tufas_ of which the
high grounds of Naples and its neighbourhood are composed. I detached a
piece of it sticking to, and incorporated with, the painted stucco of
the inside of the theatre of Herculaneum, and shall send it for your
inspection[31]. It is very different, as you will see, from the
vitrified matter called lava, by which it has been generally thought
that Herculaneum was destroyed. The village of Resina and some villas
stand at present above this unfortunate town.

To account for the very great difference of the matters that cover
Herculaneum and Pompeii, I have often thought that, in the eruption of
79, the mountain must have been open in more than one place. A passage
in Pliny's letter to Tacitus seems to say as much: "Interim è Vesuvio
monte pluribus locis latissimæ flammæ, atque incendia relucebant, quorum
fulgor et claritas tenebras noctis pellebat:" so that very probably the
matter that covers Pompeii proceeded from a mouth, or crater, much
nearer to it than is the great mouth of the Volcano, from whence came
the matter that covers Herculaneum. This matter might nevertheless be
said to have proceeded from Vesuvius, just as the eruption in the year
1760, which was quite independent of the great crater (being four miles
from it), is properly called an eruption of Vesuvius.

In the beginning of eruptions, Volcanos frequently throw up water mixed
with the ashes. Vesuvius did so in the eruption of 1631, according to
the testimony of many contemporary writers. The same circumstance
happened in 1669, according to the account of Ignazzio Sorrentino, who,
by his history of Mount Vesuvius, printed at Naples in 1734, has shewn
himself to have been a very accurate observer of the phænomena of the
Volcano, for many years that he lived at Torre del Greco, situated at
the foot of it. At the beginning of the formation of the new mountain,
near Puzzole, water was mixed with the ashes thrown up, as will be seen
in two very curious and particular accounts of the formation of that
mountain, which I shall have the pleasure of communicating to you
presently; and in 1755, Etna threw up a quantity of water in the
beginning of an eruption, as is mentioned in the letter I sent you last
year upon the subject of that magnificent Volcano[32]. Ulloa likewise
mentions this circumstance of water attending the eruptions of Volcanos
in America. Whenever therefore I find a _tufa_ composed exactly like
that which immediately covers Herculaneum, and undoubtedly proceeded
from Vesuvius, I conclude such a _tufa_ to have been produced by water
mixing with the erupted matter at the time of an explosion occasioned by
subterraneous fire; and this observation, I believe, will be of more use
than any other, in pointing out those parts of the present _terra
firma_, that have been formed by explosion. I am convinced, it has often
happened that subterraneous fires and exhalations, after having been
pent up and confined for some time, and been the cause of earthquakes,
have forced their passage, and in venting themselves formed mountains of
the matter that confined them, as you will see was the case near
Puzzole in the year 1538, and by evident signs has been so before, in
many parts of the neighbourhood of Puzzole; without creating a regular
Volcano. The materials of such mountains will have but little appearance
of having been produced by fire, to any one unaccustomed to make
observations upon the different nature of Volcanos.

If it were allowed to make a comparison between the earth and a human
body, one might consider a country replete with combustibles occasioning
explosions (which is surely the case here) to be like a body full of
humours. When these humours concentre in one part, and form a great
tumour out of which they are discharged freely, the body is less
agitated; but when, by any accident, the humours are checked, and do not
find free passage through their usual channel, the body is agitated, and
tumours appear in other parts of that body, but soon after the humours
return again to their former channel. In a similar manner one may
conceive Vesuvius to be the present great channel, through which nature
discharges some of the foul humours of the earth: when these humours are
checked by any accident or stoppage in this channel for any considerable
time, earthquakes will be frequent in its neighbourhood, and explosions
may be apprehended even at some distance from it. This was the case in
the year 1538, Vesuvius having been quiet for near 400 years. There was
no eruption from its great crater, from the year 1139 to the great
eruption of 1631, and the top of the mountain began to lose all signs of
fire. As it is not foreign to my purpose, and will serve to shew how
greatly they are mistaken, who place the seat of the fire in the centre,
or towards the top, of a Volcano; I will give you a curious description
of the state of the crater of Vesuvius, after having been free from
eruption 492 years, as related by Bracini, who descended into it not
long before the eruption of 1631: "The crater was five miles in
circumference, and about a thousand paces deep; its sides were covered
with brush wood, and at the bottom there was a plain on which cattle
grazed. In the woody parts, boars frequently harboured; in the midst of
the plain, within the crater, was a narrow passage, through which, by a
winding path, you could descend about a mile amongst rocks and stones,
till you came to another more spacious plain covered with ashes: in this
plain were three little pools, placed in a triangular form, one towards
the East, of hot water, corrosive and bitter beyond measure; another
towards the West, of water salter than that of the sea; the third of hot
water, that had no particular taste."

The great increase of the cone of Vesuvius, from that time to this,
naturally induces one to conclude, that the whole of the cone was raised
in the like manner; and that the part of Vesuvius, called Somma, which
is now considered as a distinct mountain from it, was composed in the
same manner. This may plainly be perceived, by examining its interior
and exterior form, and the strata of lava and burnt matter of which it
is composed. The ancients, in describing Vesuvius, never mention two
mountains. Strabo, Dio, Vitruvius, all agree, that Vesuvius, in their
time, shewed signs of having formerly erupted[33], and the first
compares the crater on its top to an amphitheatre. The mountain now
called Somma was, I believe, that which the ancients called Vesuvius:
its outside form is conical; its inside, instead of an amphitheatre, is
now like a great theatre. I suppose the eruption in Pliny's time to have
thrown down that part of the cone next the sea, which would naturally
have left it in its present state; and that the conical mountain, or
existing Vesuvius, has been raised by the succeeding eruptions: all my
observations confirm this opinion. I have seen antient lavas in the
plain on the other side of Somma, which could never have proceeded from
the present Vesuvius. Serao, a celebrated physician now living at
Naples, in the introduction of his account of the eruption of Vesuvius
in 1737 (in which account many of the phænomena of the Volcano are
recorded and very well accounted for), says, that at the convent of
Dominican Fryars, called the Madona del Arco, some years ago, in sinking
a well, at a hundred feet depth, a lava was discovered, and soon after
another; so that, in less than three hundred feet depth, the lavas of
four eruptions were found. From the situation of this convent, it is
clear beyond a doubt, that these lavas proceeded from the mountain
called Somma, as they are quite out of the reach of the existing
Volcano.

From these circumstances, and from repeated observations I have made in
the neighbourhood of Vesuvius, I am sure that no virgin soil is to be
found there, and that all is composed of different strata of erupted
matter, even to a great depth below the level of the sea. In short, I
have not any doubt in my own mind, but that this Volcano took its rise
from the bottom of the sea; and as the whole plain between Vesuvius and
the mountains behind Caserta, which is the best part of the Campagna
Felice, is (under its good soil) composed of burnt matter, I imagine the
sea to have washed the feet of those mountains, until the subterraneous
fires began to operate, at a period certainly of a most remote
antiquity.

The soil of the Campagna Felice is very fertile; I saw the earth opened
in many places last year in the midst of that plain, when they were
seeking for materials to mend the road from Naples to Caserta. The
stratum of good soil was in general four or five feet thick; under which
was a deep stratum of cinders, pumice, fragments of lava, and such burnt
matter as abounds near Vesuvius and all Volcanos. The mountains at the
back of Caserta are mostly of a sort of lime-stone, and very different
from those formed by fire; though Signior Van Vitelli, the celebrated
architect, has assured me, that, in the cutting of the famous aqueduct
of Caserta through these mountains, he met with some soils, that had
been evidently formed by subterraneous fire. The high grounds, which
extend from Castel-a-Mare, to the point of Minerva towards the island of
Caprea, and from the promontory that divides the bay of Naples from that
of Salerno, are of lime-stone. The plain of Sorrento, that is bounded by
these high grounds, beginning at the village of Vico, and ending at that
of Massa, is wholly composed of the same sort of _tufa_ as that about
Naples, except that the cinders or pumice stones intermixed in it are
larger than in the Naples _tufa_. I conceive then that there has been an
explosion in this spot from the bottom of the sea. This plain, as I have
remarked to be the case with all soils produced by subterraneous fire,
is extremely fertile; whilst the ground about it, being of another
nature, is not so. The island of Caprea does not shew any signs of
having been formed by subterraneous fire; but is of the same nature as
the high grounds last mentioned, from which it has been probably
detached by earthquakes, or the violence of the waves. Rovigliano, an
island, or rather a rock, in the bay of Castel-a-Mare, is likewise of
lime-stone, and seems to have belonged to the original mountains in its
neighbourhood: in some of these mountains there are also petrified fish
and fossil shells, which I never have found in the mountains which I
suppose to have been formed by explosion[34].

You have now, Sir, before you the nature of the soil, from Caprea to
Naples. The soil on which this great metropolis stands has been
evidently produced by explosions, some of which seem to have been upon
the very spot on which this city is built; all the high grounds round
Naples, Pausilipo, Puzzole, Baïa, Misenum, the islands of Procita and
Ischia, appear to have been raised by explosion. You can trace still in
many of these heights the conical shape that was naturally given them at
first, and even the craters out of which the matter issued, though to be
sure others of these heights have suffered such changes by the hand of
time, that you can only conjecture that they were raised in the like
manner, by their composition being exactly the same as that of those
mountains which still retain their conical form and craters entire. A
_tufa_, exactly resembling the specimen I took from the inside of the
theatre of Herculaneum, layers of pumice intermixed with layers of good
soil, just like those over Pompeii, and lavas like those of Vesuvius,
compose the whole soil of the country that remains to be described.

The famous grotto anciently cut through the mountain of Pausilipo, to
make a road from Naples to Puzzole, gives you an opportunity of seeing
that the whole of that mountain is _tufa_. The first evident crater you
meet with, after you have passed the grotto of Pausilipo, is now the
lake of Agnano; a small remain of the subterraneous fire (which must
probably have made the bason for the lake, and raised the high grounds
which form a sort of amphitheatre round it) serves to heat rooms, which
the Neapolitans make great use of in summer, for carrying off diverse
disorders, by a strong perspiration. This place is called the Sudatorio
di San Germano; near the present bagnios, which are but poor little
hovels, there are the ruins of a magnificent ancient bath. About an
hundred paces from hence is the Grotto del Cane; I shall only mention,
as a further proof of the probability that the lake of Agnano was a
Volcano, that vapours of a pernicious quality, as that in the Grotto
del Cane, are frequently met with in the neighbourhood of Etna and
Vesuvius, particularly at the time of, before, and after, great
eruptions. The noxious vapour having continued in the same force
constantly so many ages, as it has done in the Grotto del Cane (for
Pliny mentions this Grotto[35]), is indeed a circumstance in which it
differs from the vapours near Vesuvius and Etna, which are not constant.
The cone forming the outside of this supposed Volcano is still perfect
in many parts.

Opposite to the Grotto del Cane, and immediately joining to the lake,
rises the mountain called Astruni, which, having, as I imagine, been
thrown up by an explosion of a much later date, retains the conical
shape and every symptom of a Volcano in much greater perfection than
that I have been describing. The crater of Astruni is surrounded with a
wall, to confine boars and deers (this Volcano having been for many
years converted to a royal chace). It may be about six miles or more in
circumference: in the plain at the bottom of the crater are two lakes;
and in some books there is mention made of a hot spring, which I never
have been able to find. There are many huge rocks of lava within the
crater of Astruni, and some I have met with also in that of Agnano; the
cones of both these supposed Volcanos are composed of _tufa_ and strata
of loose pumice, fragments of lava and other burnt matter, exactly
resembling the strata of Vesuvius. Bartholomeus Fatius, who wrote of the
actions of King Alphonso the First (before the new mountain had been
formed near Puzzole), conjectured that Astruni had been a Volcano.
These are his words: "Locus Neapoli quatuor millia passuum proximus,
quem vulgo Listrones vocant, nos unum è Phlegræis Campis ab ardore
nuncupandum putamus." There is no entrance into the crater of either
Astruni or Agnano, except one, evidently made by art, and they both
exactly correspond with Strabo's description of Avernus; the same may be
said of the Solfaterra and the Monte Gauro, or Barbaro as it is
sometimes called, which I shall describe presently.

Near Astruni and towards the sea rises the Solfaterra, which not only
retains its cone and crater, but much of its former heat. In the plain
within the crater, smoak issues from many parts, as also from its sides;
here, by means of stones and tiles heaped over the crevices through
which the smoak passes, they collect in an aukward manner what they call
_sale armoniaco_; and from the sand of the plain they extract sulphur
and alum. This spot, well attended to, might certainly produce a good
revenue, whereas I doubt if they have hitherto ever cleared 200_l._ a
year by it. The hollow sound produced by throwing a heavy stone on the
plain of the crater of the Solfaterra seems to indicate, that it is
supported by a sort of arched natural vault; and one is induced to think
that there is a pool of water beneath this vault (which boils by the
heat of a subterraneous fire still deeper), by the very moist steam that
issues from the cracks in the plain of the Solfaterra, which, like that
of boiling water, runs off a sword or knife, presented to it, in great
drops. On the outside, and at the foot of the cone of the Solfaterra,
towards the lake of Agnano, water rushes out of the rocks, so hot, as to
raise the quicksilver in Fahrenheit's thermometer to the degree of
boiling water[36], a fact of which I was myself an eye-witness. This
place, well worthy the observation of the curious, has been taken little
notice of; it is called the _Pisciarelli_. The common people of Naples
have great faith in the efficacy of this water; and make much use of it
in all cutaneous disorders, as well as for another disorder that
prevails here. It seems to be impregnated chiefly with sulphur and alum.
When you approach your ear to the rocks of the Pisciarelli, from whence
this water ouzes, you hear a horrid boiling noise, which seems to
proceed from the huge cauldron, that may be supposed to be under the
plain of the Solfaterra. On the other side of the Solfaterra, next the
sea, there is a rock, which has communicated with the sea, till part of
it was cut away to make the road to Puzzole; this was undoubtedly a
considerable lava, that ran from the Solfaterra when it was an active
Volcano. Under this rock of lava, which is more than seventy feet high,
there is a stratum of pumice and ashes. This ancient lava is about a
quarter of a mile broad; you meet with it abruptly before you come in
sight of Puzzole, and it finishes as abruptly within about an hundred
paces of the town. I have often thought that many quarries of stone,
upon examination, would be found to owe their origin to the same cause,
though time may have effaced all signs of the Volcano from whence they
proceeded. Except this rock, which is evidently lava and full of
vitrifications like that of Vesuvius, all the rocks upon the coast of
Baïa are of _tufa_.

I have observed in the lava of Vesuvius and Etna, as in this, that the
bottom, as well as the surface of it, was rough and porous, like the
cinders or scoriæ from an iron foundery; and that for about a foot from
the surface and from the bottom, they were not near so solid and
compact as towards the centre; which must undoubtedly proceed from the
impression of the air upon the vitrified matter whilst in fusion. I
mention this circumstance, as it may serve to point out true lavas with
more certainty. The ancient name of the Solfaterra was, _Forum Vulcani_;
a strong proof of its origin from subterraneous fire. The degree of
heat, that the Solfaterra has preserved for so many ages, seems to have
calcined the stones upon its cone, and in its crater, as they are very
white, and crumble easily in the hottest parts.

We come next to the new mountain near Puzzole, which, being of so very
late a formation, preserves its conical shape entire, and produces as
yet but a very slender vegetation. It has a crater almost as deep as the
cone is high, which may be near a quarter of a mile perpendicular, and
is in shape a regular inverted cone. At the basis of this new mountain
(which is more than three miles in circumference), the sand upon the
sea shore, and even that which is washed by the sea itself, is burning
hot for above the space of an hundred yards; if you take up a handful of
the sand below water, you are obliged to get rid of it directly, on
account of its intense heat.

I had been long very desirous of meeting with a good account of the
formation of this new mountain, because, proving this mountain to have
been raised by mere explosion in a plain, would prove at the same time,
that all the neighbouring mountains, which are composed of the same
materials, and have exactly or in part the same form, were raised in the
like manner; and that the seat of fire, the cause of these explosions,
lies deep; which I have every reason to think.

Fortunately, I lately found two very good accounts of the phænomena that
attended the explosion, which formed the new mountain, published a few
months after the event. As I think them very curious, and greatly to my
purpose, and as they are rare, I will give you a literal translation of
such extracts as relate to the formation of the Monte Nuovo. They are
bound in one volume[37].

The title of the first is, _Dell Incendio di Pozzuolo, Marco Antonio
delli Falconi all Illustrissima Signiora Marchesa della Padula nel
MDXXXVIII_.

At the head of the second is, _Ragionamento del Terremoto, del Nuovo
Monte, del Aprimento di Terra in Pozzuolo nell' Anno 1538, é della
significatione d'essi. Per Piero Giacomo da Toledo_; and at the end of
the book, _Stampata in Nap. per Giovanni Sulztbach Alemano, a 22di
Genaro 1539, con gratia, é privilegio_.

"First then (says Marco Antonio delli Falconi), will I relate simply and
exactly the operations of nature, of which I was either myself an
eye-witness, or as they were related to me by those who had been
witnesses of them. It is now two years that there have been frequent
earthquakes at Pozzuolo, at Naples, and the neighbouring parts; on the
day and in the night before the appearance of this eruption, above
twenty shocks great and small were felt at the abovementioned places.
The eruption made its appearance the 29th of September 1538, the feast
of St. Michael the angel; it was on a Sunday, about an hour in the
night; and, as I have been informed, they began to see on that spot,
between the hot baths or sweating rooms, and Trepergule, flames of fire,
which first made their appearance at the baths, then extended towards
Trepergule, and fixing in the little valley that lies between the Monte
Barbaro and the hillock called del Pericolo (which was the road to the
lake of Avernus and the baths), in a short time the fire increased to
such a degree, that it burst open the earth in this place, and threw up
so great a quantity of ashes and pumice stones mixed with water, as
covered the whole country; and in Naples a shower of these ashes and
water fell a great part of the night. The next morning, which was
Monday, and the last of the month, the poor inhabitants of Pozzuolo,
struck with so horrible a sight, quitted their habitations, covered with
that muddy and black shower, which continued in that country the whole
day, flying death, but with faces painted with its colours; some with
their children in their arms, some with sacks full of their goods;
others leading an ass, loaded with their frightened family, towards
Naples; others carrying quantities of birds of various sorts, that had
fallen dead at the time the eruption began; others again with fish which
they had found, and were to be met with in plenty upon the shore, the
sea having been at that time considerably dried up. Don Pedro di Toledo,
Viceroy of the kingdom, with many gentlemen, went to see so wonderful
an appearance; I also, having met with the most honourable and
incomparable gentleman, Signior Fabritio Moramaldo, on the road, went
and saw the eruption and the many wonderful effects of it. The sea
towards Baïa had retired a considerable way; though, from the quantity
of ashes and broken pumice stones thrown up by the eruption, it appeared
almost totally dry. I saw likewise two springs in those
lately-discovered ruins, one before the house that was the Queen's, of
hot and salt water; the other of fresh and cold water, on the shore,
about 250 paces nearer to the eruption: some say, that, still nearer to
the spot where the eruption happened, a stream of fresh water issued
forth like a little river. Turning towards the place of the eruption,
you saw mountains of smoak, part of which was very black and part very
white, rise up to a great height; and in the midst of the smoak, at
times, deep-coloured flames burst forth with huge stones and ashes, and
you heard a noise like the discharge of a number of great artillery. It
appeared to me as if Typheus and Enceladus from Ischia and Etna with
innumerable giants, or those from the Campi Phlegrei (which, according
to the opinions of some, were situated in this neighbourhood), were come
to wage war again with Jupiter. The natural historians may perhaps
reasonably say, that the wise poets meant no more by giants, than
exhalations, shut up in the bowels of the earth, which, not finding a
free passage, open one by their own force and impulse, and form
mountains, as those which occasioned this eruption have been seen to do;
and methought I saw those torrents of burning smoak that Pindar
describes in an eruption of Etna, now called Mon Gibello, in Sicily; in
imitation of which, as some say, Virgil wrote these lines:

  "Ipse sed horrificis juxta tonat Ætna ruinis, &c.

"After the stones and ashes with clouds of thick smoak had been sent up,
by the impulse of the fire and windy exhalation (as you see in a great
cauldron that boils), into the middle region of the air, overcome by
their own natural weight, when from distance the strength they had
received from impulse was spent, rejected likewise by the cold and
unfriendly region, you saw them fall thick, and, by degrees, the
condensed smoak clear away, raining ashes with water and stones of
different sizes, according to the distance from the place: then, by
degrees, with the same noise and smoak, it threw out stones and ashes
again, and so on by fits. This continued two days and nights, when the
smoak and force of the fire began to abate. The fourth day, which was
Thursday, at 22 o'clock, there was so great an eruption, that, as I was
in the gulph of Puzzole, coming from Ischia, and not far from Misenum, I
saw, in a short time, many columns of smoak shoot up, with the most
terrible noise I ever heard, and, bending over the sea, came near our
boat, which was four miles or more from the place of their birth; and
the quantity of ashes, stones, and smoak, seemed as if they would cover
the whole earth and sea. Stones, great and small, and ashes more or
less, according to the impulse of the fire and exhalations, began to
fall, so that a great part of this country was covered with ashes; and
many, that have seen it, say, they reached the vale of Diana, and some
parts of Calabria, which are more than 150 miles from Pozzuolo. The
Friday and Saturday nothing but a little smoak appeared; so that many,
taking courage, went upon the spot, and say, that with the stones and
ashes thrown up, a mountain has been formed in that valley, not less
than three miles in circumference, and almost as high as the Monte
Barbaro, which is near it, covering the Canettaria, the castle of
Trepergule, all those buildings and the greatest part of the baths that
were about them; extending South towards the sea, North as far as the
lake of Avernus, West to the Sudatory, and joining East to the foot of
the Monte Barbaro; so that this place has changed its form and face in
such a manner as not to be known again: a thing almost incredible, to
those who have not seen it, that in so short a time so considerable a
mountain could have been formed. On its summit there is a mouth in the
form of a cup, which may be a quarter of a mile in circumference, though
some say it is as large as our market-place at Naples, from which there
issues a constant smoak; and though I have seen it only at a distance,
it appears very great. The Sunday following, which was the 6th of
October, many people going to see this phænomenon, and some having
ascended half the mountain, others more, about 22 o'clock there happened
so sudden and horrid an eruption, with so great a smoak, that many of
these people were stifled, some of which could never be found. I have
been told, that the number of the dead or lost amounted to twenty-four.
From that time to this, nothing remarkable happened; it seems as if the
eruption returned periodically, like the ague or gout. I believe
henceforward it will not have such force, though the eruption of the
Sunday was accompanied with showers of ashes and water, which fell at
Naples, and were seen to extend as far as the mountain of Somma, called
Vesuvius by the ancients; and, as I have often remarked, the clouds of
smoak proceeding from the eruption moved in a direct line towards that
mountain, as if these places had a correspondence and connection one
with the other. In the night, many beams and columns of fire were seen
to proceed from this eruption, and some like flashes of lightning[38].
We have then, many circumstances for our observation, the earthquakes,
the eruption, the drying up of the sea, the quantity of dead fish and
birds, the birth of springs, the shower of ashes with water and without
water, the innumerable trees in that whole country, as far as the Grotto
of Lucullus, torn from their roots, thrown down, and covered with ashes,
that it gave one pain to see them: and as all these effects were
produced by the same cause that produces earthquakes; let us first
enquire how earthquakes are produced, and from thence we may easily
comprehend the cause of the abovementioned events." Then follows a
dissertation on earthquakes, and some curious conjectures relative to
the phænomena which attended this eruption, clearly and well expressed,
considering, as the author himself apologizes, that at that time the
Italian language had been little employed on such subjects.

The account of the formation of the Monte Nuovo, by Pietro Giacomo di
Toledo, is given in a dialogue between the feigned personages of
Peregrino and Svessano; the former of which says, "It is now two years
that this province of Campagna has been afflicted with earthquakes, the
country about Pozzuolo much more so than any other parts; but the 27th
and the 28th of the month of September last, the earthquakes did not
cease day or night, in the abovementioned city of Pozzuolo; that plain,
which lies between the lake of Averno, the Monte Barbaro, and the sea,
was raised a little, and many cracks were made in it, from some of which
issued water; and at the same time the sea, which was very near the
plain, dried up about two hundred paces, so that the fish were left on
the sand, a prey to the inhabitants of Pozzuolo. At last, on the 29th of
the said month, about two hours in the night, the earth opened near the
lake, and discovered a horrid mouth, from which were vomited furiously,
smoak, fire, stones, and mud composed of ashes; making, at the time of
its opening, a noise like very loud thunder: the fire, that issued from
this mouth, went towards the walls of the unfortunate city; the smoak
was partly black and partly white; the black was darker than darkness
itself, and the white was like the whitest cotton: these smoaks, rising
in the air, seemed as if they would touch the vault of heaven; the
stones that followed were, by the devouring flames, converted to pumice,
the size of which (of some I say) were much larger than an ox. The
stones went about as high as a cross-bow can carry, and then fell down,
sometimes on the edge, and sometimes into the mouth itself. It is very
true that many of them in going up could not be seen, on account of the
dark smoak; but, when they returned from the smoaky heat, they shewed
plainly where they had been, by their strong smell of fetid sulphur,
just like stones that have been thrown out of a mortar, and have passed
through the smoak of inflamed gunpowder. The mud was of the colour of
ashes, and at first very liquid, then by degrees less so; and in such
quantities, that in less than twelve hours, with the help of the
abovementioned stones, a mountain was raised of a thousand paces in
height. Not only Pozzuolo and the neighbouring country was full of this
mud, but the city of Naples also, the beauty of whose palaces were, in a
great measure, spoiled by it. The ashes were carried as far as Calabria
by the force of the winds, burning up in their passage the grass and
high trees, many of which were borne down by the weight of them. An
infinity of birds also, and numberless animals of various kinds, covered
with this sulphureous mud, gave themselves up a prey to man. Now this
eruption lasted two nights and two days without intermission, though, it
is true, not always with the same force, but more or less: when it was
at its greatest height, even at Naples you heard a noise or thundering
like heavy artillery when two armies are engaged. The third day the
eruption ceased, so that the mountain made its appearance uncovered, to
the no small astonishment of every one who saw it. On this day, when I
went up with many people to the top of this mountain; I saw down into
its mouth, which was a round concavity of about a quarter of a mile in
circumference, in the middle of which the stones that had fallen were
boiling up, just as in a great cauldron of water that boils on the
fire. The fourth day it began to throw up again, and the seventh much
more, but still with less violence than the first night; it was at this
time that many people, who were unfortunately on the mountain, were
either suddenly covered with ashes, smothered with smoak, or, knocked
down by stones, burnt by the flame, and left dead on the spot. The smoak
continues to this day[39], and you often see in the night-time fire in
the midst of it. Finally, to complete the history of this new and
unforeseen event, in many parts of the new-made mountain, sulphur begins
to be generated." Giacomo di Toledo, towards the end of his dissertation
upon the phænomena attending this eruption, says, that the lake of
Avernus had a communication with the sea, before the time of the
eruption; and that he apprehended that the air of Puzzole might come to
be affected in summer time, by the vapours from the stagnated waters of
the lake; which is actually the case.

You have, Sir, from these accounts, an instance of a mountain, of a
considerable height and dimensions, formed in a plain, by mere
explosion, in the space of forty-eight hours. The earthquakes having
been sensibly felt at a great distance from the spot where the opening
was made, proves clearly, that the subterraneous fire was at a great
depth below the surface of the plain; it is as clear that those
earthquakes, and the explosion, proceeded from the same cause, the
former having ceased upon the appearance of the latter. Does not this
circumstance evidently contradict the system of M. Buffon, and of all
the natural historians, who have placed the seat of the fire of
Volcanos towards the center, or near the summit of the mountains, which
they suppose to furnish the matter emitted? Did the matter which
proceeds from a Volcano in an eruption come from so inconsiderable a
depth as they imagine, that part of the mountain situated above their
supposed seat of the fire must necessarily be destroyed, or dissipated
in a very short time: on the contrary, an eruption usually adds to the
height and bulk of a Volcano; and who, that has had an opportunity of
making observations on Volcanos, does not know, that the matter they
have emitted for many ages, in lavas, ashes, smoak, &c. could it be
collected together, would more than suffice to form three such mountains
as the simple cone or mountain of the existing Volcano? With respect to
Vesuvius, this could be plainly proved; and I refer to my letter upon
the subject of Etna, to shew the quantity of matter thrown up in one
single eruption, by that terrible Volcano. Another proof, that the real
seat of the fire of Volcanos lies even greatly below the general level
of the country whence the mountain springs, is, that was it only at an
inconsiderable depth below the basis of the mountain, the quantity of
matter thrown up would soon leave so great a void immediately under it,
that the mountain itself must undoubtedly sink and disappear after a few
eruptions.

In the above accounts of the formation of the new mountain, we are told
that the matter first thrown up, was mud composed of water and ashes,
mixed with pumice stones and other burnt matter: on the road leading
from Puzzole to Cuma, part of the cone of this mountain has been cut
away, to widen the road. I have there seen that its composition is a
_tufa_ intermixed with pumice, some of which are really of the size of
an ox, as mentioned in Toledo's account, and exactly of the same nature
as the _tufa_ of which every other high ground in its neighbourhood is
composed; similar also to that which covers Herculaneum. According to
the above accounts, after the muddy shower ceased, it rained dry ashes:
this circumstance will account for the strata of loose pumice and ashes,
that are generally upon the surface of all the _tufas_ in this country,
and which were most probably thrown up in the same manner. At the first
opening of the earth, in the plain near Puzzole, both accounts say, that
springs of water burst forth; this water, mixing with the ashes,
certainly occasioned the muddy shower; when the springs were exhausted,
there must naturally have ensued a shower of dry ashes and pumice, of
which we have been likewise assured. I own, I was greatly pleased at
being in this manner enabled to account so well for the formation of
these _tufa_ stones and the veins of dry and loose burnt matter above
them, of which the soil of almost the whole country I am describing is
composed; and I do not know that any one has ever attended to this
circumstance, though I find that many authors, who have described this
country, have suspected that parts of it were formed by explosion.
Wherever then this sort of _tufa_ is found, there is certainly good
authority to suspect its having been formed in the same manner as the
_tufa_ of this new mountain, for, as I said before, Nature is generally
uniform in all her operations.

It is commonly imagined that the new mountain rose out of the Lucrine
lake, which was destroyed by it; but in the above account, no mention is
made of the Lucrine lake; it may be supposed then, that the famous dam,
which Strabo and many other ancient authors mention to have separated
that lake from the sea, had been ruined by time or accident, and that
the lake became a part of the sea before the explosion of 1538.

If the above-described eruption was terrible, that which formed the
Monte Barbaro (or Gauro, as it was formerly called), must have been
dreadful indeed. It joins immediately to the new mountain, which in
shape and composition it exactly resembles; but it is at least three
times as considerable. Its crater cannot be less than six miles in
circumference; the plain within the crater, one of the most fertile
spots I ever saw, is about four miles in circumference: there is no
entrance to this plain, but one on the East side of the mountain, made
evidently by art; in this section you have an opportunity of seeing that
the matter of which the mountain is composed is exactly similar to that
of the Monte Nuovo. It was this mountain that produced (as some authors
have supposed) the celebrated Falernian wine of the ancients.

Cuma, allowed to have been the most ancient city of Italy, was built on
an eminence, which is likewise composed of _tufa_, and may be naturally
supposed a section of the cone formed by a very ancient explosion.

The lake of Avernus fills the bottom of the crater of a mountain,
undoubtedly produced by explosion, and whose interior and exterior
form, as well as the matter of which it is composed, exactly resemble
the Monte Barbaro and Monte Nuovo. At that part of the basis of this
mountain which is washed by the sea of the bay of Puzzole, the sand is
still very hot, though constantly washed by the waves; and into the cone
of the mountain, near this hot sand, a narrow passage of about 100 paces
in length is cut, and leads to a fountain of boiling water, which,
though brackish, boils fish and flesh without giving them any bad taste
or quality, as I have experienced more than once. This place is called
Nero's bath, and is still made use of for a sudatory, as it was by the
ancients; the steam that rises from the hot fountain abovementioned,
confined in the narrow subterraneous passage, soon produces a violent
perspiration upon the patient who sits therein. This bath is reckoned a
great specifick in that distemper which is supposed to have made its
appearance at Naples before it spread its contagion over the other
parts of Europe.

Virgil and other ancient authors say, that birds could not fly with
safety over the lake of Avernus, but that they fell therein; a
circumstance favouring my opinion, that this was once the mouth of a
Volcano. The vapour of the sulphur and other minerals must undoubtedly
have been more powerful, the nearer we go back to the time of the
explosion of the Volcano; and I am convinced that there are still some
remains of those vapours upon this lake, as I have observed there are
very seldom any water-fowl upon it; and that when they do go there, it
is but for a short time; whilst all the other lakes in the neighbourhood
are constantly covered with them, in the winter season. Upon Mount
Vesuvius, in the year 1766, during an eruption, when the air was
impregnated with noxious vapours, I have myself picked up dead birds
frequently.

The castle of Baïa stands upon a considerable eminence, composed of the
usual _tufa_ and strata of pumice and ashes; from which I concluded I
should find some remains of the craters from whence the matter issued:
accordingly, having ascended the hill, I soon discovered two very
visible craters, just behind the castle.

The lake called the Mare-morto was also, most probably, the crater, from
whence issued the materials which formed the Promontory of Misenum, and
the high grounds around this lake. Under the ruins of an ancient
building, near the point of Misenum, in a vault, there is a vapour, or
_mofete_, exactly similar in its effects to that of the Grotto del Cane,
as I have often experienced.

The form of the little island of Nisida shews plainly its origin[40]. It
is half a hollow cone of a Volcano cut perpendicularly; the half crater
forms a little harbour called the Porto Pavone; I suppose the other half
of the cone to have been detached into the sea by earthquakes, or
perhaps by the violence of the waves, as the part that is wanting is the
side next to the open sea.

The fertile and pleasant island of Procita shews also most evident signs
of its production by explosion, the nature of its soil being directly
similar to that of Baïa and Puzzole; this island seems really, as was
imagined by the ancients, to have been detached from the neighbouring
island of Ischia.

There is no spot, I believe, that could afford a more ample field for
curious observations, than the island of Ischia, called Enaria, Inarime,
and Pithecusa, by the ancients. I have visited it three times; and this
summer passed three weeks there, during which time I examined, with
attention, every part of it. Ischia is eighteen miles in circumference:
the whole of its soil is the same as that near Vesuvius, Naples, and
Puzzole. There are numberless springs, hot, warm, and cold[41],
dispersed over the whole island, the waters of which are impregnated
with minerals of various sorts; so that, if you give credit to the
inhabitants of the country, there is no disorder but what finds its
remedy here. In the hot months (the season for making use of these
baths), those who have occasion for them flock hither from Naples. A
charitable institution sends and maintains three hundred poor patients
at the baths of Gurgitelli every season. By what I could learn of these
poor patients, those baths have really done wonders, in cases attended
with obstinate tumours, and in contractions of the tendons and muscles.
The patient begins by bathing, and then is buried in the hot sand near
the sea. In many parts of the island, the sand is burning hot, even
under water. The sand on some parts of the shore is almost entirely
composed of particles of iron ore; at least they are attracted by the
load-stone, as I have experienced. Near that part of the island called
Lacco, there is a rock of an ancient lava, forming a small cavern, which
is shut up with a door; this cavern is made use of to cool liquors and
fruit, which it does in a short time as effectually as ice. Before the
door was opened, I felt the cold to my legs very sensibly; but when it
was opened, the cold rushed out so as to give me pain; and within the
grotto it was intolerable. I was not sensible of wind attending this
cold; though upon Mount Etna and Mount Vesuvius, where there are caverns
of this kind, the cold is evidently occasioned by a subterraneous wind:
the natives call such places _ventaroli_. May not the quantity of nitre,
with which all these places abound, account in some measure for such
extreme cold? My thermometer was unluckily broken, or I would have
informed you of the exact degree of the cold in this _ventaroli_ of
Ischia, which is by much the strongest in its effects I ever felt. The
ancient lavas of Ischia shew, that the eruptions there have been very
formidable; and history informs us, that its first inhabitants were
driven out of the island by the frequency and the violence of them.
There are some of these ancient lavas not less than two hundred feet in
depth. The mountain of St. Nicola, on which there is at present a
convent of hermits, was called by the ancients Epomeus; it is as high,
if not higher, than Vesuvius, and appears to me to be a section of the
cone of the ancient and principal Volcano of the island, its composition
being all _tufa_ or lava. The cells of the convent abovementioned are
cut out of the mountain itself; and there you see plainly that its
composition no way differs from the matter that covers Herculaneum, and
forms the Monte Nuovo. There is no sign of a crater on the top of this
mountain, which rises almost to a sharp point: time, and other
accidents, may be reasonably supposed to have worn away this distinctive
mark of its having been formed by explosion, as I have seen to be the
case in other mountains, formed evidently by explosion, on the flanks of
Etna and Vesuvius. Strabo, in his 5th book, upon the subject of this
island, quotes Timæus, as having said, that, a little before his time, a
mountain in the middle of Pithecusa, called Epomeus, was shook by an
earthquake, and vomited flames.

There are many other rising grounds in this island, that, from the
nature of their composition, must lead one to think the same as to their
origin. Near the village of Castiglione, there is a mountain formed
surely by an explosion of a much later date, having preserved its
conical form and crater entire, and producing as yet but a slender
vegetation: there is no account, however, of the date of this eruption.
Nearer the town of Ischia, which is on the sea shore, at a place called
_Le Cremate_, there is a crater, from which, in the year 1301 or 1302, a
lava ran quite into the sea; there is not the least vegetation on this
lava, but it is nearly in the same state as the modern lavas of
Vesuvius. Pontano, Maranti, and D. Francesco Lombardi, have recorded
this eruption; the latter of whom says, that it lasted two months; that
many men and beasts were killed by the explosion; and that a number of
the inhabitants were obliged to seek for refuge at Naples and in the
neighbouring islands. In short, according to my idea, the island of
Ischia must have taken its rise from the bottom of the sea, and been
increased to its present size by divers later explosions. This is not
extraordinary, when history tells us (and from my own observation I have
reason to believe) that the Lipari islands were formed in the like
manner. There has been no eruption in Ischia since that just mentioned,
but earthquakes are very frequent there; two years ago, as I was told,
they had a very considerable shock of an earthquake in this island.

Father Goree's account of the formation of the new island in the
Archipelago (situated between the two islands called Kammeni, and near
that of Santorini) of which he was an eye-witness, strongly confirms the
probability of the conjectures I venture to send you, relative to the
formation of those islands and that part of the continent above
described: it seems likewise to confirm the accounts given by Strabo,
Pliny, Justin, and other ancient authors, of many islands in the
Archipelago, formerly called the Ciclades, having sprung up from the
bottom of the sea[42] in the like manner. According to Pliny, in the
4th year of the CXXXVth Olympiad, 237 years before the Christian æra,
the island of Thera (now Santorini) and Theresia were formed by
explosion; and, 130 years later, the island Hiera (now called the great
Kammeni) rose up. Strabo describes the birth of this island in these
words: "In the middle space between Thera and Theresia flames burst out
of the sea for four days, which, by degrees, throwing up great masses,
as if they had been raised by machines, they formed an island of twelve
stadia in circuit." And Justin says of the same island, "Eodem anno
inter insulas Theramenem et Theresiam, medio utriusque ripæ et maris
spatio, terræ motus fuit: in quo, cum admiratione navigantium, repente
ex profundo cum calidis aquis Insula emersit."

Pliny mentions also the formation of Aspronisi, or the White Island, by
explosion, in the time of Vespasian. It is known, likewise, that in the
year 1628, one of the islands of the Azores, near the island of St.
Michael, rose up from the bottom of the sea, which was in that place 160
fathoms deep; and that this island, which was raised in fifteen days, is
three leagues long, a league and a half broad, and rises three hundred
and sixty feet above water.

Father Goree, in his account of the formation of the new island in the
Archipelago, mentions two distinct matters that entered into the
composition of this island, the one black, the other white. Aspronisi,
probably from its very name, is composed of the white matter, which if,
upon examination, it proves to be a _tufa_, as I strongly suspect, I
should think myself still more grounded in my conjectures; though I must
confess, as it is, I have scarcely a doubt left with respect to the
country I have been describing having been thrown up in a long series
of ages by various explosions from subterraneous fire. Surely there are
at present many existing Volcanos in the known world; and the memory of
many others have been handed down to us by history. May there not
therefore have been many others, of such ancient dates as to be out of
the reach of history[43]?

Such wonderful operations of Nature are certainly intended by all-wise
Providence for some great purpose. They are not confined to any one part
of the globe, for there are Volcanos existing in the four quarters of
it. We see the great fertility of the soil thrown up by explosion, in
part of the country I have described, which on that account was called
by the ancients _Campania Felix_. The same circumstance is evident in
Sicily, justly esteemed one of the most fertile spots in the world, and
the granary of Italy. May not subterraneous fire be considered as the
great plough (if I may be allowed the expression), which Nature makes
use of to turn up the bowels of the earth, and afford us fresh fields to
work upon, whilst we are exhausting those we are actually in possession
of, by the frequent crops we draw from them? Would it not be found, upon
enquiry, that many precious minerals must have remained far out of our
reach, had it not been for such operations of Nature? It is evidently so
in this country. But such great enquiries would lead me far indeed. I
will only add a reflection, which my little experience in this branch of
natural history furnishes me with. It is, that we are apt to judge of
the great operations of Nature on too confined a plan. When first I came
to Naples, my whole attention, with respect to natural history, was
confined to Mount Vesuvius, and the wonderful phænomena attending a
burning mountain: but, in proportion as I began to perceive the evident
marks of the same operation having been carried on in the different
parts above described, and likewise in Sicily in a greater degree, I
looked upon Mount Vesuvius only as a spot on which Nature was at present
active; and thought myself fortunate in having an opportunity of seeing
the manner in which one of her great operations (an operation, I
believe, much less out of her common course than is generally imagined)
was effected.

Such remarks as I have made on the eruptions of Mount Vesuvius, during
my residence at Naples, have been transmitted to the Royal Society, who
have done them more honour than they deserved. Many more might be made
upon this active Volcano, by a person who had leisure, a previous
knowledge of the natural history of the earth, a knowledge of chemistry,
and was practised in physical experiments, particularly those of
electricity[44]. I am convinced, that the smoak of Volcanos contains
always a portion of electrical matter; which is manifest at the time of
great eruptions, as is mentioned in my account of the great eruption of
Vesuvius in 1767. The peasants in the neighbourhood of my villa,
situated at the foot of Vesuvius, have assured me, that, during the
eruption last mentioned, they were more alarmed by the lightning and
balls of fire that fell about them with a crackling noise, than by the
lava and the usual attendants of an eruption. I find in all the accounts
of great eruptions mention made of this sort of lightning, which is
distinguished here by the name of _Ferilli_. Bracini, in his account of
the great one of Vesuvius in 1631, says, that the column of smoak, which
issued from its crater, went over near an hundred miles of country, and
that several men and beasts were struck dead by lightning, issuing from
this smoak in its course.

The nature of the noxious vapours, called here _mofete_, that are
usually set in motion by an eruption of the Volcano, and are then
manifest in the wells and subterraneous parts of its neighbourhood, seem
likewise to be little understood. From some experiments very lately
made, by the ingenious Dr. Nooth, on the _mofete_ of the Grotto del
Cane, it appears that all its known qualities and effects correspond
with those attributed to fixed air. Just before the eruption of 1767, a
vapour of this kind broke into the King's chapel at Portici, by which a
servant, opening the door of it, was struck down. About the same time,
as his Sicilian Majesty was shooting in a paddock near the palace, a dog
dropped down, as was supposed, in a fit; a boy going to take him up
dropped likewise; a person present, suspecting the accident to have
proceeded from a _mofete_, immediately dragged them both from the spot
where they lay, in doing which, he was himself sensible of the vapour;
the boy and the dog soon recovered. His Sicilian Majesty did me the
honour of informing me himself of this accident soon after it had
happened. I have met with these _mofetes_ often, when I have been making
my observations on the borders of Mount Vesuvius, particularly in
caverns, and once on the Solfaterra. The vapour affects the nostrils,
throat, and stomach, just as the spirit of hartshorn, or any strong
volatile salts; and would soon prove fatal, if you did not immediately
remove from it. Under the ancient city of Pompeii, the _mofetes_ are
very frequent and powerful, so that the excavations that are carrying on
there are often interrupted by them; at all times _mofetes_ are to be
met with under ancient lavas of Vesuvius, particularly those of the
great eruption of 1631. In Serao's account of the eruption of 1737, and
in the chapter upon _mofetes_, he has recorded several curious
experiments relative to this phænomenon. The Canonico Recupero, who, as
I mentioned to you in a former letter, is watching the operations of
Mount Etna, has just informed me, that a very powerful _mofete_ has
lately manifested itself in the neighbourhood of Etna; and that he
found, near the spot from whence it rises, animals, birds, and insects,
dead, and the stronger sort of shrubs blasted, whilst the grass and the
tenderer plants did not seem to be affected. The circumstance of this
_mofete_, added to that of the frequent earthquakes felt lately at
Rhegio and Messina, makes it probable that an eruption of Mount Etna is
at hand.

I am alarmed at the length of this letter. By endeavouring to make
myself clearly understood, I have been led to make, what I thought,
necessary digressions. I must therefore beg of your goodness, that,
should you find this memoir, in its present state, too tedious (which I
greatly apprehend) to be presented to our respectable Society, you will
make only such extracts from it as you shall think will be most
agreeable and interesting. I am,

                              SIR,
                              With great truth and regard,
                              Your most obedient
                              humble servant,

                              W. HAMILTON.


[Illustration: _Plate VI._]

REFERENCES to the MAP,
[Plate VI.]

   1. Naples.

   2. Portici.

   3. Resina, under which Herculaneum is buried.

   4. Torre del Greco.

   5. Hermitage, at which travellers usually rest, in their way up
      Mount Vesuvius.

   6. St. Angelo, a convent of Calmaldolese, situated upon a cone of
      a mountain formed by an ancient explosion.

   7. Cones formed by the eruption of 1760, and lava that ran from
      them almost into the sea.

   8. Mount Vesuvius and Somma.

   9. Village of Somma.

  10. The convent of the Madona del Arco, under which lavas have
      been found at 300 feet depth, and which must have proceeded
      from the mountain of Somma, when an active Volcano.

  11. Ottaiano.

  12. Torre del Annunziata.

  13. Castel a Mare, near which the ancient town of Stabia is
      buried, and where Pliny the elder lost his life.

  14. Vico.

  15. Sorrento, and the plain formed evidently by subterraneous
      fire.

  16. Massa.

  17. Island of Caprea.

  18. The Grotto of Pausilipo, cut through the mountain anciently,
      to make a road from Naples to Puzzole.

  19. Point of Pausilipo.

  20. The Gaiola, where there are ruins of ancient buildings,
      supposed to have belonged to Lucullus.

  21. The island of Nisida, evidently formed by explosion.

  22. The Lazaret.

  23. The Bagnoli.

  24. Puzzole, or Pozzuolo.

  25. The Solfaterra, anciently called Forum Vulcani: between the
      Solfaterra and the lake of Agnano, are the boiling waters of
      the Pisciarelli.

  26. The New Mountain, formed by explosion in the year 1538; the
      sand of the sea shore at its basis burning hot.

  27. The lake of Agnano, supposed the crater of an ancient Volcano:
      here are the baths called St. Germano, and the famous Grotto
      del Cane.

  28. Astruni, which has been evidently a Volcano, and is now a
      Royal Chace, the crater being surrounded with a wall.

  29. The Monte Gauro or Barbaro, anciently a Volcano.

  30. The lake of Avernus, evidently the crater of an ancient
      Volcano.

  31. Lake of Fusaro.

  32. Point of Misenum, from whence Pliny the elder discovered the
      eruption of Vesuvius that proved fatal to him; near this
      place, in a vault of an ancient building, is a constant
      vapour, or _mofete_, of the same quality with that of the
      Grotto del Cane.

  33. The Mare Morto, the ancient Roman Harbour.

  34. Baïa; behind the castle are two evident craters of ancient
      Volcanos.

  35. Island of Procita.

  36. A perfect cone and crater of a Volcano near Castiglione in the
      island of Ischia.

  37. Lava that ran into the sea in the last eruption on this
      island, in the year 1301, or 1302: the place now called Le
      Cremate.

  38. Town of Ischia and castle.

  39. Lake of Licola.

  40. Lake of Patria.

  41. The river Volturnus.

  42. Capua.

  43. Caserta.

  44. Aversa.

  45. Mataloni.

  46. Acerra.

  47. Island of Ischia, anciently called Ænaria, Inarime, and
      Pithecusa.

  48. The mountain of St. Nicola, anciently called Mons Epomeus,
      supposed the remains of the principal Volcano of the island.

  49. Castiglione, near which are the baths of Gurgitelli.

  50. Lacco, near which is that very cold vapour called by the
      natives _ventarole_.

  51. Ancient city of Pompeii, where his Sicilian Majesty's
      excavations are carrying on at present.

  52. Rovigliano.

  53. River of Sarno.

  54. Cuma.

  55. Hot sands and sudatory, called Nero's baths.

  56. The Lucrine lake, supposed to have been here, and of which
      there is still some little remain.

  57. Villa Angelica, Sir William Hamilton's villa, from whence he
      has made many of his observations upon Mount Vesuvius.

  58. Cones formed by an ancient eruption called _viuli_; here are
      likewise cold vapours called _ventaroli_.

  59. High grounds, probably sections of cones of ancient Volcanos,
      being all composed of _tufa_ and strata of loose pumice and
      burnt matter.

  60. Plain of the Campagna Felice, four or five feet of excellent
      soil, under which are strata of burnt and erupted matter.

  ...... Marks the boundary of Sir William Hamilton's observations.




LETTER VI.[45]

To MATHEW MATY, M. D. Secretary to the Royal SOCIETY.


                              Naples, March 5, 1771.

Since I had the pleasure of sending you my letter, in which the nature
of the soil of more than twenty miles round this capital is described;
examining a deep hollow way cut by the rain waters into the outside cone
of the Solfaterra, I discovered, that a great part of the cone of that
ancient Volcano has been calcined by the hot vapours above described.
Pumice calcined seems to be the chief ingredient, of which several
specimens of (as I suppose) variegated unformed marble are composed, and
the beautiful variegations in them may have probably been occasioned by
the mineral vapours. As these specimens are now sent to the Royal
Society, you will see that these variegations are exactly of the same
pattern and colours as are met in many marbles and flowered alabasters;
and I cannot help thinking that they are marble or alabaster in its
infant state. What a proof we have here of the great changes the earth
we inhabit is subject to! What is now the Solfaterra, we have every
reason to suppose to have been originally thrown up by a subterraneous
explosion from the bottom of the sea. That it was long an existing
Volcano, is plain, from the ancient currents of lava, that are still to
be traced from its crater to the sea, from the strata of pumice and
erupted matter, of which its cone, in common with those of other
Volcanos, is composed, and from the testimony of many ancient authors.
Its cone in many parts has been calcined, and is still calcining, by the
hot vapours that are continually issuing forth through its pores; and
its nature is totally changed by this chemical process of Nature. In the
hollow way, where I made these remarks, you see the different strata of
erupted matter, that compose the cone, in some places perfectly
calcined, in others not, according as the vapours have found means to
insinuate themselves more or less.

A hollow way, cut by the rains on the back of the mountain on which part
of Naples is situated, towards Capo di China, shews that the mountain is
composed of strata of erupted matter, among which are large masses of
bitumen, in which its former state of fluidity is very visible. Here it
was I discovered that pumice stone is produced from bitumen, which I
believe has not yet been remarked. Some specimens shew evidently the
gradual process from bitumen to pumice: and you will observe that the
crystalline vitrifications, which are visible in the bitumen, suffer no
alteration, but remain in the same state in the perfect pumice as in the
bitumen.

In a piece of stratum, calcined from the outside of the Solfaterra, the
form and texture of the pumice stones is very discernible. In several
parts of the outside cone, this calcining operation is still carried on,
by the exhalation of constant very hot and damp vapours, impregnated
with salts, sulphur, alum, &c. Where the abovementioned vapours have not
operated, the strata of pumice and erupted matter, that compose the cone
of the Solfaterra, are like those of all the high grounds in its
neighbourhood, which I suppose to have been thrown up likewise by
explosion. I have seen here, half of a large piece of lava perfectly
calcined, whilst the other half out of the reach of the vapours has
been untouched; and in some pieces the centre seems to be already
converted into true marble.

The variegated specimens then, above described, are nothing more than
pumice and erupted matter, after having been acted upon in this manner
by the hot vapours; and if you consider the process, as I have traced
it, from bitumen to pumice, and from pumice to marble, you will think
with me, that it is difficult to determine the primitive state of the
many wonderful productions we see in Nature.

I found, in the _tufa_ of the mountain of Pausilipo, a fragment of lava:
one side I polished, to shew it to be true lava; the other shews the
signs of the _tufa_, with which it is incorporated. It has evidently
been rounded by friction, and most probably by rolling in the sea. Is it
not natural then to imagine that there must have been Volcanos near this
spot, long before the formation of the mountain of Pausilipo? This
little stone may perhaps raise in your mind such reflections as it did
in mine, relative to the great changes our globe suffers, and the
probability of its great antiquity.


FOOTNOTES:

[1] Having reflected since upon this circumstance, I rather believe that
the weight of the atmosphere in bad weather, preventing the free
dissipation of the smoke, and collecting it over the crater, gives it
the appearance of being more considerable; whereas in fine weather the
smoke is dispersed soon after its emission. It is, however, the
common-received opinion at Naples (and from my own observation is, I
believe, well founded), that when Vesuvius grumbles, bad weather is at
hand. The sea of the Bay of Naples, being particularly agitated, and
swelling some hours before the arrival of a storm, may very probably
force itself into crevices, leading to the bowels of the Volcano, and,
by causing a new fermentation, produce those explosions and grumblings.

[2] These ashes destroy the leaves and fruit, and are greatly
detrimental to vegetation for a year or two; but are certainly of great
service to the land in general, and are among the principal causes of
that very great fertility which is remarkable in the neighbourhood of
Volcano's.

[3] In the subsequent eruptions of Vesuvius, I have constantly remarked
something of the same nature, as appears in my account of the great
eruption of 1767. I have found the same remark in many accounts of
former eruptions of Vesuvius: in the very curious one of the formation
of a new mountain near Puzzole, in 1538, (as may be seen in my letter to
Dr. Maty, Oct. 16, 1770[46],) the same observation is made. This
phænomenon, is well worthy of a curious inquiry, which might give some
light into the theory of the earth, of which, I believe, we are very
ignorant.

[4] I am convinced, that it might be very practicable to divert the
course of a lava when in this state, by preparing a new bed for it, as
is practised with rivers. I was mentioning this idea at Catania in
Sicily, when I was assured, that it had been done with success during
the great eruption of Etna, in 1669; that the lava was directing its
course towards the walls of Catania, and advancing slowly like the
abovementioned, when they prepared a channel for it round the walls of
the town, and turned it into the sea; that a succession of men, covered
with sheep-skins wetted, were employed to cut through the tough flanks
of the lava, till they made a passage for that in the centre (which was
in perfect fusion) to disgorge itself into the channel prepared for it.
A book I have since met with gives the same account of this curious
operation; it is intituled, _Relatione del nuovo incendio fatto da
Mongibello 1669. Messina, Giuseppe Bisagni, 1670_. His Sicilian
Majesty's palace at Portici, and the valuable collection of antiquities
that have been recovered from beneath the destructive lava's of
Vesuvius, are in imminent danger of being overwhelmed again by the next
that shall take its course that way; whereas, by taking a level, cutting
away and raising ground, as occasion might require, the palace and
museum would, in all probability, be insured, at least against one
eruption; and, indeed, I once took the liberty of communicating this
idea to the King of Naples, who seemed to approve of it.

[5] The late Lord Morton was pleased to give these specimens to Dr.
Morris, who has made several chemical experiments on them, the result of
which will be communicated to the Royal Society.

[6] From what I have seen and read of eruptions of Vesuvius and Etna, I
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 Ægyptum 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
phænomenon. 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 illæ 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 phænomenon; 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. Romæ_,
MDCLXI, a very philosophical account is given of this phænomenon; 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 Ætna, 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° 4-2/3', half way up this little
mountain it was at 19° 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 cælestia numina thure
    "Summo cerne jugo, vel quâ liberrimus Ætna
    "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 æra 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 à Liparo rege, qui successit
Æolo, 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 Æolus, quæ à Lipara liquidiore
flamma tantum differt: e cujus fumo equinam flaturi sint venti, in
triduum prædicere incolæ traduntur; unde ventos Æolo 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 Baïanis, et in agris municipiorum, quæ sunt circa
Vesuvium montem, quod commixtum cum calce et cæmento non modo cæteris
ædificiis præstat firmitates, sed etiam moles, quæ 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 flammæ 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 formatæ in unam pervenerint mixtionem, repente
recepto liquore una cohærescunt, et celeriter humore duratæ solidantur,
neque eas fluctus, neque vis aquæ potest dissolvere."

About Baïa, 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, perché dopò
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 hæc loca situs
est Vesuvius mons agris cinctus optimis: dempto vertice, qui magna sui
parte planus, totus sterilis est, adspectu cinæreus, 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, "Phlegræus quoque campus is locus appellatur a colle
nimirum, qui Ætnæ instar Siculæ magnam vim ignis eructabat; nunc
Vesuvius nominatur, multa inflammationis pristinæ 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 verò novis cladibus, vel post
longam sæculorum repetitis afflictæ, haustæ aut abrutæ fecundissima
Campaniæ 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. Quæst. lib. vi. cap. 28. "Pluribus Italiæ
locis per quædam foramina pestilens exhalatur vapor, quem non homini
ducere, non feræ tutum est. Aves quoque si in illum inciderint, antequam
coelo meliore leniatur, in ipso volatu cadunt, liventque corpora, et non
aliter quam per vim elisæ 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°.

[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 aëra saxis."

                              Lucan. lib. vi.

[41] Giulio Cesare Capaccio, in his account of this island, says, that
there are eleven springs of cold water, and thirty-five of hot and
mineral waters.

[42] By having remarked, that all the implements of stone brought by
Mess. Banks and Solander from the new-discovered islands in the
South-Seas, are evidently of such a nature as are only produced by
Volcanos; and as these gentlemen have assured me, that no other kind of
stone is to be met with in the islands; I am induced to think, that
these islands (at so great a distance from any continent) may have
likewise been pushed up from the bottom of the sea by like explosions.

[43] Any one, the least conversant in Volcanos, must be struck with the
numberless evident marks of them the whole road from the lake of Albano
to Radicofani, between Naples and Florence; and yet, though this soil
bears such fresh and undoubted marks of its origin, no history reaches
the date of any one eruption in these parts.

[44] May not the air in countries replete with sulphur be more
impregnated with electrical matter than the air of other soils? and may
not the sort of lightning, which is mentioned by several ancient authors
to have fallen in a serene day, and was considered as an omen, have
proceeded from such a cause?

Horace says, Ode xxxiv.

            "--Namque Diespeter
    "Igni corusco nubila dividens
      "Plerumque per purum tonantes
        "Egit equos volucremque currum."

      "Non alias coelo ceciderunt plura sereno
      "Fulgura----"

                              Virgil. Georgic. i.

    "Aut cum terribili perculsus fulmine civis
    "Luce serenanti vitalia lumina liquit."

                              Cic. i. de Divin. n. 18.

  "--Sabinos petit aliquanto tristior, quod sacrificanti hostia
  aufugerat: quodque tempestate serena tonuerat."

                              Sueton. _Tit._ cap. 10.

[45] This letter was not received by Dr. Maty in its present form: and
is rather the substance of an explanatory catalogue, which was sent to
that gentleman with sundry specimens of the different materials that
compose the soil described in the preceding letter; which catalogue
remains, with the specimens, in the Museum of the Royal Society, for the
inspection, and, I flatter myself, the satisfaction, of the curious in
natural history.

[46] See p. 103 of this collection.

[47] See Letter I. p. 18.

[48] Having heard the same remark with respect to the lava's of
Vesuvius, I determined, during an eruption of that Volcano, to watch the
progress of a current of lava, and I was soon enabled to comprehend this
seeming phænomenon; though it is, I fear, very difficult to explain.
Certain it is, that the lava's, whilst in their most fluid state, follow
always the law of other fluids; but when at a great distance from their
source, and consequently incumbered with scoriæ and cinders, the air
likewise having rendered their outward coat tough, they will sometimes
(as I have seen) be forced up a short ascent, the fresh matter pushing
forward that which went before it, and the exterior parts of the lava
acting always as conductors (or pipes, if I may be allowed the
expression), for the interior parts, that have retained their fluidity
by not having been exposed to the air.

[49] The flames Lord Winchelsea mentions, were certainly produced by the
lava having met with trees in the way; or perhaps his Lordship may have
mistaken the white smoak which constantly rises from a lava (and in the
night is tinged by the reflection of the red hot matter), for flame, of
which indeed it has greatly the appearance at a distance. I have
observed upon Mount Vesuvius, that, soon after a lava has borne down and
burned a tree, a bright flame issues from its surface; otherwise I have
never seen any flame attending an eruption.


THE END.




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Transcriber's Notes


This document was taken from hand-written letters in the eighteenth
century, and also contains quotes from other authors. As such, it's no
surprise that there are many spelling and punctuation irregularities.
Except where explicitly noted below, these were kept as is. Spelling
variants that were preserved include: "Abbate" and "Abate;"
"abovementioned" and "above-mentioned;" "Ænaria" and "Enaria;" "ancient"
and "antient" (and derivatives); "Astruni" and "Astroni;" "Averno" and
"Avernus;" "Giulio Cesare Bracini" and "Giulio Cesare Bruccini;"
"Castel-a-Mare," "Castel-a-mare," "Castel a Mare" and "Castle-a-Mare;"
"centre" and "center;" "colour" and "color" (and derivatives); "deer"
and "deers" (for the plural of "deer"); "enquiry" and "inquiry;"
"entirely" and "intirely;" "entituled" and "intituled;" "exteriour" and
"exterior;" "honour" and "honor;" "interiour" and "interior;" "lavas"
and "lava's" (for the plural of "lava"); "Mare-morto" and "Mare Morto;"
"mere" and "meer;" "Mon-Gibello," "Mongibello," "Mon Gibello," "Monte
Gibello" and "Mount Gibel;" "o'clock" and "a clock;" "Procida" and
"Procita;" "rain water" and "rain-water;" "smoke" and "smoak" (and
derivatives); "Solfaterra" and "Solfa terra;" "strata" and "stratas"
(for the plural of "stratum"); "Torre dell' Annunciata," "Torre dell'
Annunziata" and "Torre del Annunziata;" "Volcanos" and "Volcano's" (for
the plural of "Volcano"); "Volcano's" and "Volcanos" (for the possessive
of "Volcano").

Changed "that" to "than" on page 85: "on the top of Vesuvius than on
that of Etna."

Changed "thermomether" to "thermometer" on page 122: "Fahrenheit's
thermometer."

Inserted missing word "a" on page 129: "fell a great part of the night."

A small right-pointing hand appeared at the beginning of the last line
of the advertisement. It was replaced by two asterisks.

In the text version of this book, the oe-ligature character was replaced
by the separate characters, "oe."