[' ] PHILOSOPHICAL TRANSACTIONS. » I. I .11.. I -.1 . ill., ■ ■ ■ ■■! ■ ■■■ . .. I. .. -* Received January 24, 1768. I. An Account of the Eruption of Mount Vefuvius, in 1767 : In a Letter to the Earl of Morton, Prejident of the Royal Society^ from the Honourable William Hamilton, His Majeflys Envoy Extra- ordinary at Naples. Naples, December 29, 1767. My Lord, Read Feb. ii,r | iHE favourable reception, which my 17^8. J^ account of laft year's eruption of Mount Vefuvius met with from your Lordfhip, the approbation which the Royal Society was pleafed to {hew, by having ordered the fame to be printed in Vol. LVIIl. B their - [ o their Phllofophlcal Tranfadtlons, and your Lordihip^s commands in your letter of the 3d inftant, encourage me to trouble you with a plain narrative of what came immediately under my obiervation during the late violent eruption, which began Odober 19, i^^J^ and is reckoned to be the 27th lince that, which, in the time of Titus, delfroyed Herculaneum and Pompeii. The eruption of 1766 continued in fome degree till the loth of December, about nine months in ail^ yet in that fpace of time the moutain did not caft up a third of the quantity of lava,, which it difgorg.ed in only {(tVQ,n days, the term of this lad eruption^ On the 15th of December, lafb year, within the ancient crater of Mount Vefuvius, and about twenty feet deep, there was a crufl, which formed a plain, not unlike the folfaterra in miniature ; in the midfl: of this plain was a little mountain, whofe top did not rife fo high as the rim of the ancient crater. I went into this plain, and up the little mountain, which was perforated, and ferved as the principal chimney to the volcano -, when I threw down large ftones, I could hear that they met with many ob- ftrudiions in their way, and could count a hundred moderately before they reached the bottom. 'Vefuvius was quiet till March 1767, when it be- gan to throw up ftones, from time to time; in April the throws were more frequent, and at night fire was viable on the top of the mountain \ or, more pro- perly fpeaking, the fmoak, which hung over the crater, was tinged by the reflection of the fire within the volcano. Thefe repeated throv/s of cin- ders, afhes, and pumice ftones, encreafed the lirile 5 mountain- [3 3 ihountaln Co much, that in May its top was vidble above the rim of the ancient crater. The 7th of Auguft there ilTued a fmall ftream of lava, from a breach in the fide of this Httle mountain, which gradually filled the valley between it and the ancient crater; fo that the 12th of September the lava over- flowed the ancient crater, and took its courfe down the fides of the great mountain ; by this time, the throws were much more frequent, and the red hot ftones went f© high as to take up ten feconds in their fall. Padre Torre, a great obferver of Mount Ve- fuvius, fays they went up a hove 1 000 feet. The 15th of Odober, the height of the little mountain (formed in about eight months) was mea- fured by Don Andrea Pigonati, a very ingenious young man in his Sicilian majefly's fervice, v/ho afilired me that its height was 185 French feet. From my villa, fituated between Herculaneum and Pompeii, near the convent of the Calmaldolefe (marked 7 in the inclofed Plan I.), I had watched the growing of this little mountain, and by taking drawings of it from time to time, I could perceive its increafe moft minutely ; I make no doubt but that the whole of Mount Vefuvius has been formed in the fame manner ; and as thefe obfervations feem to me to account for the various irregular llrata, which are met with in the neighbourhood of volcanos, I have ventured to enclofe for your Lordfhip's infpe(5lion a copy of the abovementioned drawings. The lava continued to run over the ancient crater in Imall flreams, fometimes on one fide, and fome times on another, till the 18th of Odober, when I took particular notice that there was not the B 2 lead [ 4. ] _ leaft lava to be feen, owing, I imagine, to its being employed in forcing its way towards the place where it buift out the following day. As I had, contrary to the opinion of mofl people here, foretold the approaching eruption % and had ohferved a great fermentation in the mountain after the heavy rains, which fell the 13th and 14th of Odtober, I was not furprifed on the 19th following, at feven of the clock in the morning, to perceive from my villa every fymptom of the eruption being juft at hand. From the top of the little mountain iffued a thick black fmoak, fo thick that it feemed to have difficulty in forcing its way out; cloud after cloud moutited "vvith a hafty fpiral motion, and every minute a volley of great ftones were fliot up to an immenfe height in the midfl of thefe clouds ; by degrees, the fmoak took the exadt fhape of a huge pine tree, fuch as Pliny the younger defcribed in his letter to Tacitus, where he gives an account of the fatal eruption in which his uncle perifhed^. This column of black fmoak, * This plainly appears from the following extract of a letter, from the fame gentleman to the prefidcnt, dated Naples, OtSto- ber 6, 1767. *' Mount Vefuvius is preparing for another *' eruption, or rather a fecond part of the lafl-, as it has never '* been quiet fince the beginning of the year 1765. The lava *' already runs over the crater; and by the quantity of ftones " and afhes, the montagnola has almoft filled the crater, and *' has rifen at leaft 80 feet within thefe laft three months." ^ Thefe are his words. *' Nubes (incertum procul intuenti- " bus ex quo monte Vefuvium fuifie poftea cognitum eft) orie- *' batur, cujus fimilitudinem & formam, non alia magis arbor, ** quam pinus exprcflerit. Nam longifTnno vehiti trunco elata " in altum, quibufdam ramis diffundebatur, credo quia recenti " fpiritu evedta, dein fenefcente eo deftituta, aut etiam pondere *' fuo vi£ta, in latitudinem evanefcebat : Candida interdum, in- *' terdum fordida & maculofa, prout terram cineremve fuftu- «* lerat." Plin. Lib. VI. Ep. 16. after f 5 ] after having mounted an extraordinary height, bent with the wind towards Capita, and adually reached over that iiland, which is not lefs than 28 miles from Vefuvius. I warned my family not to be alarmed, as I ex- pedited there would be an earthquake at the moment of the lava's burfting out ; but before eight of the clock in the morning I perceived that the mountain had opened a mouth, without noife, about loo yards lower than the ancient crater, on the fide towards the Monte di hommaj and I plainly perceived, by a white fmoak, which always accompanies the lava, that it had forced its way out : as foon as it had vent, the fmoak 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, 1 went up immediately, accompanied by one peafant only. I pafTed the hermitage (3. in Plan 1.), and proceeded as far as the fpot marked ( X )? in the valley between the mountain of Somma and that of Vefuvius, which is called Atrio di Cavallo. 1 was making my obfervations upon the lava, which had ah-eady, from the fpot (E) v/here it firft broke out, reached the valley, when, on a fudden, about noon, I heard a violent noife within the mountain, and at the fpot (C) about a quarter of a mile oif the place v/here I ftood, the mountain fplit ; and, with much noife, from this new mouth a fountain of li- quid fire fliot up many feet high, and then like a torrent rolled en dire6lly towards us. The earth fliook at the fame time, that a volley of pumice flones fell thick upon us j in an infl:ant, clouds of black fmoak and afl:ies caufed almoil a total darknefs 3 the explo- £ons^ [6] fions from the top of the mountain were much louder than any thunder I ever heard, and the fmell of the fulphur was very offenfive. My guide alarm- ed took to .his heels j and I muft confefs that I was not at my eafe. I followed clofe, and we ran near three miles without flopping ; as the earth con- tinued to fhake under our feet, I was apprehenfive of the opening of a frefh mouth, which might have cut off our retreat. 1 alfo feared that the violent explolions would detach fome of the rocks off the mountain of Somma, under which we were obliged to' pafs ; beiides, the pumice-itones, falling upon us hke hail, were of fuch a fize as to caufe a difagreeable fenfation upon the part where they fell. After having taken breath, as the earth flill trembled greatly, I thought it moil prudent to leave the mountain, and return to my villa, where I found my funily in a great alarm at the continual and violent explofions of the volcano, which fhook our houle to its very foundation, the doors and windows fv/inging upon their hinges. About two of the clock in the afternoon another lava forced its way out of the fame place from whence came the lava laft year, at the fpot marked B (in Plan II.), fo that the con- iiagration was foon as great on this fide of the moun- tain as on the other, which I had juft left. The noife and fmell of fulphur encreafing, we removed from our villa to Naples ; and I thought proper, as I paffed by Portici, to inform the court of what I had feen ; and humbly offered it as my opinion, that his Sicilian majefty (liould leave the neighbourhood of the threatening mountain. How- ever, the court did not leave Portici till about twelve of the clock, when the lava had reached as far' as (4. in [7] (4. in Plan. I.) I obferved, in my way to Naples, which was in lefs than two hours after I had left the mountain, that the lava had a(5lual]y covered three miles of the very road through which we had re- treated. It is a{lonifl:jing that it fhould have run fo faft i as I have fince feen, that the river of lava, in the Atrio di Cavallo, v^as 60 and 70 feet deep, and in fome places near two miles broad. When his Sicilian majefly quitted Portici, the noife was greatly increafed, and the confulion of the air from the ex- plolions was fo violent, that, in the king's palace, doers and windows weie forced open, and even one door there, wlilch was locked, was neverthelefs burfh open. At Naples, the fame night, many windows and doors flew open ; in my houfe, which is not on the fide of the town next Vefuvius, 1 tried the ex- periment of unbolting my windows, when they flew wide open upon every exploflon of the mountain.- Befides thefe exploflon s, which were very frequent^, there was a continued fubterraneous and violent rumbling noife, which lafied this night about Ave hours. I have imagined that this extraordinary noife might be owing to the lava in the bovi'els of the mountain having met with a depofition of rain wa- ter, and that the conflid: between the fire and the water may, in fome meafure, account for fo ex- traordinary a crackling and hifling noife. Padre Torre, who has wrote i'o much and fo Well upon the fubjedl; of Mount Vefuvius, is alfo of my opinion 5 . and indeed it is natural to imagine, that there may be rain water lodged in many of the caverns of the niountain, as, in the great eruption of Mount Vefu- vius in 1,663, it is V7eli attelled, that feveral towns^ among f 8] among which Portici and Torre del Greco, were deftroyed by a torrent of boiling water having burfl out of the mountain with the lava, by which thoufands of lives were loft. About four years ago, Mount Etna in Sicily threw up hot water alfo, during an eruption. The confufion at Naples this night cannot be de- fcribed; his Sicilian majefty's hafty retreat from Portici added to the alarm ; all the churches were opened and filled, the ftreets were thronged with proceffions of faints j but I (hall avoid entering upon a defcription of the various ceremonies that were performed in this capital, to quell the fury of the turbulent mountain. Tuefday the 20th, it was impoffible to judge of the fituation of Vefuvius, on account of the fmoak and afhes which covered it entirely, and fpread over Naples alfo, the fun appearing as through a thick London fog, or a fmoaked glals ; fmall afhes fell all this day at Naples. The lavas on both fides of the mountain ran violently j but there was little or no noife till about nine o'clock at night, when the fame uncommon rumbling began again, accompanied with explofions as before, which lafted about four hours ; it feemed as if the mountain would fplit in pieces ; and, indeed, it opened this night almoft from the fpot E to C (in Plan I.). The inclofed plans were taken upon the fpot at this time, when the lava's were at their height; and I do not think them exaggerated. The Parifian barometer was, as yefterday, at 27. 9, and Fahrenheit's thermometer at 70 degrees ; whereas, for fome days preceding the eruption, it had beeen at 65 and 66. During the coniulion . . f 9] confufion of this night the prifoners in the publick jail attempted to efcape, having wounded the jailer, but were prevented by the troops. The mob ahb fet fire to the cardinal archbifliop's gate, becaufe he refufed to bring out the relicks of Saint Januarius. Wednefday 21ft was more quiet than the pre« ceding days, though the lavas ran brifkly. Portici was once in fome danger, had not the lava taken a different courfe, when it was only a mile and a half from it j towards night the lava flackened. Thurfday 2 2d, about ten of the clock in the morning, the fame thundering noife began again, but with more violence than the preceding days; the oldeft men declared they had never heard the like, and, indeed, it was very alarming ; we were in ex- pedlation every moment of fome dire calamity. The afhes, or rather fmall cinders, fliowered down fo faft, that the people in the ftreets were obliged to ufe umbrellas, or flap their hats, thefe aflies being very offenfive to the eyes. The tops of the houfes, and the balconies, were covered above an inch thick with thefe cinders. Ships at fea, twenty leagues from Naples, were alfo covered with them, to the great aftonlfliment of the failors. In the midft of thefe horrors, the mob growing tumultuous and impatient, obliged the cardinal to bring out the head of Saint Januarius, and go with it in proceffion to the Ponte Maddalena, at the extremity of Naples, towards Vefuvius ; and it is well attefted here, that the eruption ceafed the moment the Saint came in fight of the mountain ; it is true the noife ceafed about that time, after having lafted five hours, as it had done the preceding days. Vol. LVIII. C Friday [ ^o ] ' Friday 23d, the lavas ftjll ran, and the mountain continued to throw up quantities of ftones from its crater; there was no nolfe heard at Naples this day, and but Httle afhes fell there. Saturday 24.th, the lava ceafed running j the ex- tent of the lava, from the fpot C (Plan I.), where I faw it break out, to its extremity F, where it fur- rounded the chapel of Saint Vito, is above fix miles. In the Atrio di Cavallo, and in a deep valley, that lies between Vefuvius (i.), and the hermitage (3.), the lava is in fome places near two miles broad, and in moft places from 60 to 70 feet deep ; at { 4.) the lava ran down a hollow way, called Fofia grande, made by the currents of rain water j it is not lefs than 200 feet deep, and 100 broad j yet the lava in one place has filled it up. I could not have believed that fo great a quantity of matter could have been thrown out in fo fhort a time, if I had not fince examined the whole courfe of the lava my- felf. This great compad: body will certainly retain fome heat many months ; at this time, much rain having fallen for fome days paft, the lava fmoaks, as if it ran a-frelh: and about ten days ago, when I, was up the mountain with Lord Stormont, we thruft Hicks into the crevices of the lava, which took, fire immediately : But to proceed with my journal. The 24th Vefuvius continued to throw up flones as on the preceding days -, during the whole of this eruption it had differed in this circumflance from the eruption of 1766, when no Hones were thrown out of the crater from the moment the lava ran freely. Sunday ?5th, fmall afhes fell all day at Naples 5 they iiiued from the crater of the volcano;, and formed , . 5 ■ a vafk a vaft column, as black as the mountain Itfelf, fo that the fliadow of it was marked out on the furface of the fea; continual flashes of forked, or zig-za^ lightning fliot 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 iky at this time, except thofe of fmoak iffuing from the crater of Vefuvius. I was much pleafed with this phenomenon, which I had not feen before in that perfection. Monday 26th, the fmoak continued, but not fo thick, neither were there any flashes of the mountain lightning. As no lava has appeared after this column • of black fmoak, which muft have been occafioned by fome inward operation of fire, I am apt to think that the lava, which fliould naturally have followed this fymptom, has broke its way into fome deeper cavern, where it is filently brooding future mifchief j and I fliall be much miftaken if it does not break out a few months hence. Tuefday 27th, no more black fmoak, nor any figns of eruption. Thus, My Lord, I have had the honor of giving your Lordfliip a faithful narrative of my obfervations during this eruption, which is univerfally allowed to have been the moft violent of this century -, and I fhall be happy if it fhould meet with your approba- tion, and that of the Royal Society, if your Lord- fhip (hould think it worthy of being communicated to fo refpedable a body. I have juft fent a prefent to the Britifh Mufeum of a compleat collection of every fort of matter pro- duced by Mount Vefuvius, which I have been col- C 2, letting C 12 ] ledling with fome pains for thefe three years part ; and it will be a great fatisfadtlon to me if, by the means of this collection, fome of my countrymen, learned in natural hiftory, may be enabled to make fome ufeful difcoveries relative to volcanos s I have alfo accompanied that coUedtion with a current of lava from Mount Vefuvius; it is painted with tranfparent colours, and, when lighted up with lamps behind it, gives a much better idea of Vefu- vius, than is poflible to be given by any other fort q£ paintings I have the honor to be. My Lord, Your Lordfhip's mofl obedient, and mofl humble fervant,. William Hamilton^ « " lam well convinced, by this colleflion, that many vari- ** egated marbles, and many precious ftones, are the produce ** of volcanos ; and that there have been volcanos in many parts '* of the world, where at prefent there are no traces of them ** vifible," This is taken from a prior letter of Mr. Hamilton,, to the Prefident, dated April 7, 1767. PLATE [ ^3 ] PLATE L A. Crater of Mount Vefuvius. B. Mouth from whence came the lava of 1766 ; and which opened afrefh, Odober 19, 1767, and produced the conflagration reprefented in Plan II. C. The mouth which opened at 12 o'clock, Oc- tober 19, 1767, whilfl: I was at the fpot marked xj from thence came all the lava= reprefented in Plan I. D. The lava. E. Mouth from whence the lava flowed, at eight o'clock, Oftober 1 9, when the eruption be- gan firfl. F. Chapel of Saint Vito furrounded with lava. 1. Vefuvius. 2. Mountain of Somma. 3. Hermitage, between which and Vefuvius there- is a deep valley two miles broad. 4. The Fofla Grande. 5. His Sicilian Majefl:y's Palace at Portici. 6. Church of Pugliano. 7. Calmaldolefe Convent, near which is my Villa^ 8. Saint Torio. 9. Barra. io. Spot, under which lies Herculaneum. PLATE. [ 14 3 PLATE II. A. Crater of Vefuvius. B. Mouth, from whence came the lava of 1766, and which opened afrelh at two o'clock, OAober 19, 1767, and caufed the confla- gration on this fide of the mountain. C. Mouth which opened at 12 o'clock, Odlober 19, 1767, whilfl I was at the fpot x, and which produced all the lava reprefented in Plan 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 Vefuvius. 3. Montagna di Trecafe. 4. Trecafe. 5. Oratorio di Boico. 6. Ottaiano. PLATE in. Views of the gradual increafe of the little mountain within the ancient crater ; and of the prefent ihape of Mount Vefuvius, Received Mmmim ' t'^/i/i/ s f^ /'^6y. m 9 'i-iti\'. I't-.vi.iXf/.i.viii. r^R. m,f'. 14. ^'/iW/i //if ///•iii/iia/ //i,/;;i.', ,'/'//u- M- ///,'i/ii/mii /.■///iiii //i,- ( -nt/.r -> .■/^Tf.,/rn.-ur/-/.icA /<«.: ma,-i(.< ,„.-A ,«wa.u:/^ Mr ,,,/rmw M//e,//m,- ,'/h»v M, .iA,/,- „p/„ /,///,: J/l,;,„/,„„ /'f/r/r //„,/ ,',,rn;,,v , .;> //,a///ir ,/^//^/i,ul«Mr'jnm'iH'/'//ir ////• ///,.mi/m,, , '/rr/f/gf* Mr /t///r j/,r>f K.maM.i ir/irrr Mr /.ir.l nimr ,'ii/.m«r M,,/.i /j^/v //ir^^i'r.r/ ('>m/,/iim <• ji.c.d Mtif/- Mir ,mrir/if C-'rw/rr /^ v. Mr /iM/r , i/,vnMmi Mr ,>,,!/ /-r/w Mlr(''ni/l/ir,,,vx.,.,Mr ^/,r..r,,/ f ni/rr, i^ Mr r.r/rr„.ur /■/.„■/ //h,- „ r <: Mr ,/.hr.,rii/ .M„/ir ,fMr A'/, ^ ///.■„„/ 'Ir ■ I'lirrr //l,ii/ /,!,•/ Mr ■ ///riiii/nitl '■■■■Y'"' ./,'/„r/,, '-r d(^^'^^