Observations on Mount Vesuvius, Mount Etna, and Other Volcano's: in a series of letters addressed to the Royal Society from the Honorable Sir William Hamilton, London, T. Cadell, 1774.

{These original letters use the old style letter s, which is much like an f. I t has been retained here although a letter f has been used for this s The computer does not support the f with only the left half ot the cross-bar which is the letter s which was used in this document]

The part of this book excerpted here was also published (without footnotes) in the Proceedings of the Royal Society. London.

              O B S E RVAT I O NS

		     O N

           M O U N T  VE S UV I US


-~  .		   I N

           A SERIES OF L ETTERS,

     Addreffed to T H E  R O YA L  S O C I ET Y,

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

His Magefty's Envoy Extraordinary and Plenipotentiary
           	at the Court of N A P L E S,

               	    To which are added,

       	Explanatory Notes by the A U T H O R
              	hitherto unpublifhed,

	    	    A NEW EDITION

                  	       L O N D O N,
    	Printed for T. CA D E L L, in the Strand,

              TH E  E D I T O R



     HAVING mentioned to Sir
     general Defire of all Lovers of Natu
     ral History, that his Letters upon the
     Subject of VOLCANO should be col
     leflced together in one Volume, par
     ticularly for the Convenience of fuch
     as may have an Opportunity of vifit
     ing the curious Spots defcribed in
     them: He was not only pleafed to 
     approve of my having undertaken, 
     this Pub1ication, but has likewife.  
     favoured with the additional explana-
     tory Notes and Drawings,

        The PUBLIC 'S  moft obliged,

		and devoted:

         			 humble  .Servant

				T.  CADELL

May 30, 1772. 
The following are excerpts from Letter #5, in part, pages 125-149. It is the description of the birth of the volcano Monte Nuevo, in 1538



..... We come next to the new mountain near Puzzole, which, being of fo very late a formation preferves its conical fhape entire,and produces as yert a very slender vegetation, It has A crater alnost as deep as the cone is high,which may be near aquarter of a mile perpendicular, and in fhape is a regular inverted cone. At the bafis of this new mountain (which is more than three miles in circumference), the



fand upon the fea shore, and even that which is washed by the sea itsfelf, is burn- ing hot for above the fpace of an hundred yards; if you take up a handful .of the fand. below water, you are, obliged: to get rid of it directly, on acc.ount af its intenfe heat.

I had been long very defirous of meeting with a good account. of the formation of this new mountain, because, proving this mountain to have been raifed by mere explofion in a plain, would prove at the fame time, that all the neighbouring moun- tains, which are compofed .of the fame ma- terials, and have exactly or in part the fame form, were raifed in the like manner; and that the feat of fire the caufe of their explofions, lies deep ;. which I have every reafon to think.

. Fortunately, I lately found two very good accounts of the phenomena that at- tended the explofton, which formed the new mountain, publifhed a few months after the event. As I think them very cur



ious, and greatly to my purpofe, and as they are rare, I will give you a literal tranf- lation of. fuch extracts as relate to the formation of the Monte Nuovo. They are bound in one volume [footnote o]. The title of the firft is, Dell Incendio di Pozzuolo, (Marco Antonio delli Falconi all illuftirfifma Signiora Marchefa della Padula nel MDXXXVIII.

At the head of :the recond is, Ragiona- mento del Terremoto, del Nuovo Monte,, del Aprimento di Terra in Pozzuolo nell' Anno I538, é della Jigniicatione d'effi Per Piero Giacomo da Toledo; and at the end of the book,Stampata in :Nap,: per Giovianni Sulztbach. Alemano, a 22di Genaro IS39, con gratia, é privilegio.

" Firft then (fays Marco Antonio delli' 
" Falconi)  will I relate fimply and exactly 
'' the operations of nature,. of which I was 
" either myfelf  an eye-witnefs, or as they 
" were related to. me by thofe who had
[footnote o] This very fcarce volume has been prefented by Sir William Hamilton to the British Mufeum. M. M.



" been witneffes 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. tlie night before the ap-
" pearance  of this.eruption, above twenty  
" fhocks great and fmall were felt at the
" abovementioned places. The eruption.
" made its appearance the 29th of Septem-
" ber 1538, the feaft of St. Michael the
" ngel; it was on a Sunday, about an~
" hour in the night; and as I have  been
" informed, they began to fee on that fpot,
" between the hot baths or fweating
''.rooms, and Trepergule, flames of fire~
" which firt made their appearance at
" the baths, then extended towards Tre-
" pergule, and fixing in the little valley that  
" lies. between the Monte Barbaro and the  
" hillock called del Pericolo (which was
" the: road, tothe lake of Avernus and
" the  baths), in a fhort time the fire in-
" creafed to fuch a degree, that.it burft
" open the earth in this place, and threw


     " up fo great a quantity of afhes and
     " plumice ftones mixed with water as
     " covered the whole country; and. in Na-
     " ples a fhower of thefe afhes and water
     " fell great part of the night. The next
     " morning, which was Monday, and the
    " laft of the month, the poor inhabitants
    " of Pozzuolo, ftruck with fo horrible a
    " fight, quitted their habitations, cover-
    " ed with that muddy and black fhower,
    " which continued in that country the
    " whole day, flying death, but with faces
    " painted with its colours; fome with their
    " children in their arms, fome with facks
    " full of their goods; others leading an
    " afs loaded with their frightened family,
    " towards Naples; others carrying quan-
    " tities of birds of various forts, that had
     " fallen dead at the time the eruptior
     " began; others again with fifh which they
     " had found, and were to be met with-
     " in plenty. upon the fhore, the fea hav-
     " ing been at that time confiderably driecl
     " up. Don Pedro di Toledo, Viceroy 


"  of the kingdom, with many gentlemen, 
"  went to fee fo wonderful an appear-
"  ance, I alfo, having met with the moft 
"  honourable and incomparable gentle- 
'' man, Signior Fabritio  Moramaildo, on 
" the road, went and faw the eruption 
" and the many wonderful efects of it. 
" The fea towards Baïaut;a had retired a 
" confiderable way; though, from the 
" quantity of afhes and broken pumice 
" ftones thrown up by the eruption, it 
" appeared almofc totally dry. I faw 
" likewife two fprings in thofe lately-dif- 
" covered ruins, one before the houfe that
" was the Queen's, of hot and falt water;
" the other of frefh and cold  water, on
" the fhore, about 250 paces nearer to
" the eruption: fome fay, that, ftill nearer
"  to the fpot where the cruption hap-
" pened, :a ftream of  frefh water iffued 
" fortlh like a little river turning to- 
" wards the place of the eruption, you 
" faw mountains of fmoak,  part of which 
" was very black and part very white, 


" r ife up to  a great height; and in the
" midft of the fmoak, at times, deep-co-
" 1oured flames buft forth with huge
" ftones and afhes, and you heard a noife
" like the dicharge of a number of great
" artillery , It appeared to me as if Ty-
" pheus and Enceladus from Ifhia and
" Etna with innumerablel giants, or thofe 
" from the Campi Phlegrei (which, ac-
" cording  to the opinions of fome, were
"  fituated in this neighborhod), were  
" come to wage war again with Jupiter.
" The natural hiftorians may perhaps rea- 
" fonably fay, that the wife poets meant
" no more by giants, than by exhalations,
" fhut up in the bowels of the earth,
" which, not finding a free paffage, open
" one by their own force and impulfe and
" form mountains, as thofe which occa-
" fioned this eruption hae been feen to
" do; and methought I faw thofe torrsnts
" of burning fmoak that Pindar defcribes
" in an eruption of Etna, now called
" Mon Gibello, in Sicily, in imitation of


" which, as fome fay, Virgil wrote: thefe 
" lines: 
" Ipfe fed horrificis juxta tonat Aetna ruinis, &c.
" After the ftones and afhes with clouds 
" of thick fmoak had been fent up, by 
" the impulfe of the fire and windy ex-
" halation (as you fee in a great cauldron 
" that boils), into the middle region of 
" the air, overcome by their own natural 
" weight, when from diftance the ftrength 
" they had received from impulfe was 
" fpent, rejected likewife by the cold and 
" unfriend]y region, you faw them fall 
" thick, and, by degrees, the condenfed 
" fmoak clear away, raining afhes with 
" water and ftones of different fizes, 
" according to the diftance from the place: 
" then, by degrecs, with the fame noife 
" and fmoak, it threw out ftones and afhes 
" ag;ain, and fo on by fits.  This con-
" tinued two days and nights , when the 
" fmoak and force of the fire began to 
" abate. The fourth day, which was 


  " Thurfday, at 22 o'clock, there was fo
  " great an eruption, that, as I was in the
  " gulph of Puzzole, coming from Ifchia~
  " and not far from Mifenum, I faw, in'
  " a fhort time, many columns of fmoak
  " fhoot up, with the moft terrible noife
  " I ever heard, and, bending over the fea
  " came near our boat, which was four
  " miles or more from the place of their
  " birth, and the quantity of afhes, ftones,'
  " and fmoak, feemed. as if they would'
  " cover the whole earth and fea. Stones,
  ".great and fmall, and anles more or lefs,'
  " according ~o 'the rmpuli[e of the fire
   " and exhalations, began to fall, fo that
   " a great part of this country was cover
   " ed vith afhe.s; and many, that have feen
   " it, fay, they reached the vale of Diana
   " ancl fome parts of Calabria\ which are
   " more than 150 miles from Pozzuolo.
   " The Friday and Saturday nothing but
   " a little fmoak appeared; fo that many,
   " taking courage, went upon the fpot
    "and fay, that with the ftones and afhes

I 3 4

" thrown up, a moutain has been £orm-
 "ed in the vallley not less than three
" miles in circumference, and almoft 
" as high as Monte Barbaro; which is
" near it, covering the Canetteria, the caftle
 " of Treperguele, all thofe buildings and   
 " the greatest of the baths that were
"  about them; extending South towards
 " the fea, North as far as the lake of
 " Avernus, Weft to the fudatory, and
  " joining Eaft to the foot of th¢: Monte
   " Barbaro; fo that this pla£e.haf changed
   " its form and face in fuch a manner as
    " not to be known again: a thing almoft
   " incredible to thofe who have not feen
    " it, that in fo fhort a time fo considera-
    " able a mountain could have been form-
    " ed. On its fummit there is a mouth,   
    " in the form of a  cup, which may be a
    " quarter of a mile. in circumference
    " though fome fay it is as large as our
    " market-place at Naples~ from which 
    " there iffues a conftant fmoak; and
    " though I have feen it only at a diftance,


" it appears very great. The Sunday fol-
" lowing which was the 6th of October,
" many people going to fee this phaeno-
" menon, and fome having afcended half
" the mountain, others more, about 22
" o'clock there happened fo fudden and
" horrid an eruption, wiith fo great a
" fmoak that many of thefe  people were
" ftiffled, fome of which could never be
" found. I have been told, that the num-
" ber of the dead or loft amounted to
" twenty-four, From that time to this, 
" nothing remarkable happened;  it feems
" as if the eruption returned periodically,
" like the ague or gout. I believe hence-
" forward it will not have fuch force,
" though the eruption of the unday was
" accompanied with fhowers of afhes and
" water, which fell at Naples and were
" feen to extend as far as the mountain
" of Somma, called Vefuvius by the an-
" cients; and, as I have ofen remarked,
" the clouds of fmoak proceeding. from
" the eruption moved in a direct line


" towards that mountain, as if there places 
" had a correfpondence and connectfion 
" one with the other. In the night, many 
' beams and columns of fire were feen 
" to proceed from this eruption, and fome 
" like flafhes of lightning [footnote p]. We have 
" then, many circumftances for our ob-  
" ervation, the earthquakes, the eruption, 
" the drying up of the fea, the quantity 
" of dead fiifh and birds, the birth of 
" fprings, the fhower of afhes with water 
" and without water, the innumerable trees   
" in that whole country, as far as the 
" Grotto of Lucllllus, torn from their 
" roots, thrown down, and covered with
" afhes, that it gave one pain to fee them : 
" and as all thefe effects were produced by 
" the fame caufe tbat produces earth-
" quakes; let us firft enquire how earth- 
" quakes are produced, and from thence 
" we may earlly comprehend the caufe of 
" the abovementioned events" .....
[footnote p] Here again we have an example of the electrical fire attending a great eruption

. ____


........ The account of the formation of the Monte Nuovo, by Pietro Giacomo di To- ledo, is given in a dialogue between the feigned perfonages of Peregrino and Svef- fano; the former of which fays,

" It is 
" now two years that this province of   
" Campagna has been afflicted with earth- 
" quakes, the country about Pozzuolo 
" much more fo than any other parts; but 
" the 27th and the 28th of the month of 
" September laft, 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 fea, was raifed a little,
" and many cracks were made in it, from
" fone of which iffued water; and at the


" fame time the sea whi¢h was very near the
" plain, dried up about two ;hundred paces
" fo that the fifh were Ieft on the fand,
" a prey to the inhabitants Pozuolo.
" At last on the 29th of the faid month,
" about two hours in the night the earth
" opened near the lake and difcovered a 
" a horrid mouth from vhich were vo-
" mited  furioufly fmoak, fire, flames, and        
" mud compofed of afhes; making, at the
" time of its opening, a noife like very 
" loud thunder: the £ire tht iffued from 
" his mouth, went~towards the walls of 
" the unfortunate city; the fmoak was 
" partly black and partly white; the  black
" was darker than darknefs itfelf, and the
" white was like the whiteft cotton; thefe 
" fmoaks, rifing inthe air feemed as if
" they would touch the vault of heaven;
" the ftones that followed were by the
" devouring, flames converted to pumi¢e,
" the fize of which (of fome I. fay) were
" much larger than an ox. The ftones
" went about as high as a crofs-bow can


" carry, and then fell down, fometimes 
" on the edge, and fometimes into  the 
" mouth itfelf;. It is very true that may 
"-af them in going up could not be feen, 
" on account of the dark fmoak; but, 
" when they returned from the fmoaky 
" heat, they fhewed plainly where they 
" had been, by their ftrong fmell of fetid 
" fulphur, juft like ftones that have been 
" thrown out of a mortar, and have paf
" fed through the: fmoak~of inflamed gun-
" powder, The mud was of the colour 
" of aflhes, and at: firft very liquid, then 
" by degrees lefs fo; and in fuch quan
" tites, that in leff than twelve hours, 
" with the help of the abovementioned 
" ftones, a rnountain was raifed of a 
" thoufand paces; in height. Not only 
" Puzzuolb and the nei;ghbouring country
" was full of  mud, but the city of
" Naples alfo the beauty of whose pa-
" laces were, in a great meafure, fpoiled 
" by it. The afhes were carried as far as 
" Calabria by the force of the winds,  


" burning up in their paffaage the grafs 
" and high trees, many of which were ~
 "borne down by the weight of them, 
" An infinity of birds alfo, and number- 
" lefs animals of various kinds, covered
" with this sulphureous mud, gave them- 
" felves up a prey to man. Now this 
" eruption laIted two nights and two days 
" without interuption, talhough, it is true, 
" not always .with the fame force, but 
" more or lers; when it was at its greatest~ 
" height, even at Naples you heard a 
" noife or thundering like heayy artillery 
" when two armies are engaged. The 
" third day the eruption ceafed, fo that 
" the mountain made its appearance un- 
" covered~ to the no rmall aftonifhment 
" of every one who faw it. On thif 
" day, when I went up witk many peo-
 "ple to the top of the mountain, I faw 
" down into its mouth which was a round 
"conccavity of about a quarter of a mile 
"in circumf ereni n the middle of whic h 
"the ftones that had fallen were boil-


" ing up, juft 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 ftill with lefs 
" violence than the firft night, it was at this
" time that many people, who were un- 
" fortunately on the mountain are either 
" fuddenly covered with afhes, fmothered 
" with frnoak, or, knocked dqwn by ftones, 
" burnt by the flame, and left dead on the 
" fpot The fmoak continues ;to this 
" day [footnote q], and you often fee in the.night  
" time fire in the middle of it.  Finally, to 
" complete the hiftory of this new and 
" unforefeen event, in many parts of the 
" new-made mountain, fulphur begins to
" be generated." 
Giacorno di Toledo, towarcls the end of his differtation, upon

[footnote q] The cup or crater on the top of the new mountain is now covered with fhrubs; but I difcovered at the buttom of it, in the year 1770, amidft the bufhes, a fmall hole which exhales a conftant hot and damp vapour juft fuch as proceeds from boiling water, .and with as little fmell; the drops of this fteam hang upon the neighboring bufhes.



the phaenomena attending this eruption, fays,, that the lake of Avernus had a communication with the fea, before the time of the eruption; and that he apprehehended that the air of Pozzole might come to be affected in fummer time, by the vapours from the ftagnated waters of the lake which is actually the case.

You have, Sir, from thefe accounts, an inftance of a mountain, of a confiderable height and dunenfions, formed in a plain, by a mere explosion, in the fpace of forty eight hours. The earthrquakes having been fenfibly felt at a great diftance from the fpot where the opening was made, proves clearly, that the fubterraneous fire was at a great depth below the furface of the plain, it is alfo clear that thofe earthquakes, and the explosion, proceeded from the caufe, the former having ceafed upon the appearance of the latter. Does no t this circumlftance evidently contradict the fyftem of M. Buffon, and of all the natural hiftorians, who have placed the feat of the fire



of Volcanoes towards the center, or near the fummit of tle mountains, which they fuppofe to furnifh the matter emitted? Did the matter which- proceeds from a Volcano in an eruption come fo incoonfiderable a depth as they imagine, that part of the mountain fituated above their fuppofed seat of the the fire be diftoyed, or diffpated in a very fhort time; on the contrary, an eruption usually adds to the height and bulk of a Volcano; and who, that had an opportunity of making obfervations on Volcanoes does not know, that the matter they have ernittef for many ages, in lawaS, afhhes, fmoak, &c. could it be collected together, would more than fuffice to form three fuch mountains as the fimple cone or mountain of the exifting volcano? With rerpect to Vefuvius, this could be plainly proved; and I refer to my letter upon the fubject of Etna, to fhew the quantity of rnatter thrown up in one fingle eruption, by that terrible Volcano. Anotehr proof, that the real feat of the fire of Vol-



canos lies even greatIy below the generat. level of the country whence the mountain fprings, is, that was it only at an inconfiderable depth below the bafis of the mountain, the quantity of matter thrown up would foon leave fo great a void immediately under: it, that the mountain itfelf muft undoubtedly fink and diffappear after a few eruptions

In the above accounts of the formation of the new mountain, we are told that the matter firft.thrown up, was mud compofed of water and afhes, mixed with pumice ftones 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 feen that its comporltion is a tufa intermixed with pumice, fome of which are really of the f1ze of an ox, as mentioned in Toledo's account, and exacrtly of the fame nature a;s the tufa of which every other high ground in its neighbourhood is compofed, fimilar alfo to that which covers



Herculaneum. According to the above accounts, after the muddy fhower ceafed, it rained dry afhes: this circumftance w;ll ac count for the frata of loofe. pumice and afhes, that are generally upon the furface of all the tufas in this country, and which were moft probably thrown up in the fame manner. At the firft opening of the earth, in the plain near Puzzole, both accounts fay, that fprings of water burft forth; this water, mixing with the afhes, certainly occafioned the muddy fhower: when the fprings were exhaufted, there muft naturally have enfued a fhower of dry afhes ancl pumice, of which we have been likewife affured. I own, I was greatly pleafed at being in this manner enabled to account fo well for the formation of there tufa ftones and the veins of dry and loofe burnt matter above them, of which the foil of almoft the whole country I am defcribing is cornpofed; and I do not know that any one has ever attendided to this circumftance, though I f1nd that many authors, who have



defcribed this country, have fufpected that parts of it were formed by explofion. Wherever then this fort of tufa is found, there is certainly good authority to fufect its having been formed in the fame manner as the tufa of this new mountain; for, as 1 faid before, Nature is g;enerally uniform in all her operations.

It is commonly imagined that the new mountain rofe out of the Lucrine lake, which was defcroyed by it; but in the above accont no mention is made of the Lucrine lake, it may be fuppofed then, that the famous dam. which Strabo and many other ancient authors mention to have fparated that lake from the fea, had been ruined by time or accident, and that the lake becarne a part of the fea before the explofion of I538. .....

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