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OBSERVATIONS
ON
MOUNT VESUVIUS,
MOUNT ETNA,
AND OTHER VOLCANOS:

IN
A SERIES OF LETTERS,

Addressed to THE ROYAL SOCIETY,

From the Honourable Sir W. HAMILTON,
K.B. F.R.S.

His Majesty's Envoy Extraordinary and Plenipotentiary
at the Court of NAPLES.

To which are added,

Explanatory NOTES by the AUTHOR,
hitherto unpublished.

A NEW EDITION.

LONDON,
Printed for T. CADELL, in the Strand.
M DCC LXXIV.




THE EDITOR
TO
THE PUBLIC.


Having mentioned to Sir WILLIAM HAMILTON the general Desire of all
Lovers of Natural History, that his Letters upon the Subject of VOLCANOS
should be collected together in one Volume, particularly for the
Convenience of such as may have an Opportunity of visiting the curious
Spots described in them: He was not only pleased to approve of my
having undertaken this Publication, but has likewise favoured with the
additional explanatory Notes and Drawings,

                              The PUBLIC's most obliged,
                              and devoted
                              humble Servant,

                              T. CADELL.

May 30, 1772.




OBSERVATIONS
ON
MOUNT VESUVIUS, &c.




LETTER I.

To the Right Honourable the Earl of MORTON, President of the Royal
Society.


                              Naples, June 10, 1766.

My LORD,

As I have attended particularly to the various changes of Mount
Vesuvius, from the 17th of November 1764, the day of my arrival at this
capital; I flatter myself, that my observations will not be unacceptable
to your Lordship, especially as this Volcano has lately made a very
considerable eruption. I shall confine myself merely to the many
extraordinary appearances that have come under my own inspection, and
leave their explanation to the more learned in Natural Philosophy.

During the first twelvemonth of my being here, I did not perceive any
remarkable alteration in the mountain; but I observed, the smoke from
the Volcano was much more considerable in bad weather than when it was
fair[1]; and I often heard (even at Naples, six miles from Vesuvius) in
bad weather, the inward explosions of the mountain. When I have been at
the top of Mount Vesuvius in fair weather, I have sometimes found so
little smoke, that I have been able to see far down the mouth of the
Volcano; the sides of which were incrusted with salts and mineral of
various colors, white, green, deep and pale yellow. The smoke that
issued from the mouth of the Volcano in bad weather was white, very
moist, and not near so offensive as the sulphureous steams from various
cracks on the sides of the mountain.

Towards the month of September last, I perceived the smoke to be more
considerable, and to continue even in fair weather; and in October I
perceived sometimes a puff of black smoke shoot up a considerable height
in the midst of the white, which symptom of an approaching eruption grew
more frequent daily; and soon after, these puffs of smoke appeared in
the night tinged like clouds with the setting sun.

About the beginning of November, I went up the mountain: it was then
covered with snow; and I perceived a little hillock of sulphur had been
thrown up, since my last visit there, within about forty yards of the
mouth of the Volcano; it was near six feet high, and a light blue flame
issued constantly from its top. As I was examining this phaenomenon, I
heard a violent report; and saw a column of black smoke, followed by a
reddish flame, shoot up with violence from the mouth of the Volcano; and
presently fell a shower of stones, one of which, falling near me, made
me retire with some precipitation, and also rendered me more cautious of
approaching too near, in my subsequent journies to Vesuvius.

From November to the 28th of March, the date of the beginning of this
eruption, the smoke increased, and was mixed with ashes, which fell, and
did great damage to the vineyards in the neighbourhood of the
mountain[2]. A few days before the eruption I saw (what Pliny the
younger mentions having seen, before that eruption of Vesuvius which
proved fatal to his uncle) the black smoke take the form of a pine-tree.
The smoke, that appeared black in the day-time, for near two months
before the eruption, had the