rich in fertility and cultivation, cities the most ancient and popu lous, have been loft beneath stones and afhes, or overwhelmed by fiery torrents; their very fite has been ingulphed, and become the vortex of eruption, or the bafon of a peftilential lake. Equally beyond the power of human prefcience to forefee, or of human energy to controul, thefe terrible operations are fometimes directed to devaftate countries of ancient formation, and fometimes to create new territories, whofe future fertility tends to repay the defolation that accompanied their production.

The most celebrated and most delightful portions of Italy have been modified or formed by the agency of fire. The rock of the Capitol, which Roman vanity called eternal, is the tottering edge of a crater; and the Campania Felice has been the creation of fucceffive lavas, and owes its exuberant fertility to frequent flowers of volcanic afhes.

Italy prefents every variety and gradation of volcanic and pfeudovolcanic phænomena. Near its northern boundary, the bafalts and amygdaloids of the Vincentine are of dubious formation; and the Euganean mountains in the Paduan territory have not an indifputed claim to an igneous origin. The tranfverfe portion of the Appenines, from Parma to Bologna, is noted for eructations of mud, and emiflions of inflamed gas; and the fouth of Tufcany contains the celebrated Lagoni, and the extinct volcanoes of Monte Fiora and Radicofani. The weftern ftates of the Church prefent a vaft extent of territory, univerfally allowed to be volcanic, ftretching, without interruption, from Aquapendente to Veletri, forming the environs of the lake of Bolfena, the hills of Montefiafcone and the Montagna di Viterbo, extending eaft to between Borghetto and Otricoli, and fpreading over the vait plain of Rome. It touches the limestone of the Appenincs at Tivoli, forms the hills of Frascati, surrounds the huge crater that contains the lake of Albano, and probably communicates by the valley of Anagni with the volcanic diftrict of the Terra di Lavoro.

The limestone of the Appenines, which skirt the Pontine marfhes from Piperno to Terracina, extends along the coaft by Fondi to Gaeta, and nearly to the River Liris or Garigliano. Thefe volcanic fubftances appear to form the bafis of the valley, and probably extend to Soza and Anagni. Towards the fouth, Mignano, Teano, Calvi, Capua, Caferta, Nola Sarno, and Sorrento, are all fituated within the eastern boundary of the volcanic territory, which comprehends the whole fpace weftward to the fea, forming the celebrated Campania Felice. It is encircled by limeftone, stretching from Gaeta to the Cape of Minerva; and, excepting the Monte Maffico, and the hill near Calvi, which are fimestone, all included in this boundary is entirely of igneous

origin.

origin. Nor are the volcanic fubftances confined within thefe limits. They form the bafis of the valley of the Volturnus, and the whole extent between Cerelo and St Agata di Goti; they reach up the Calore towards Beneventum, up the Claudine valley; and, ftretching beyond Nocerra, they form the bafis on which ftands Salerno.

The various parts of this extenfive diftrict will be regarded with unequal intereft. The lavas of Seffa, Rocca, Monfine, and Teano, flowed at a period far antecedent to hiftory; the fertile foil of the Campania conceals the pumices, tufas, and afhes, which form its bafis; and they, in their turn, bury the lavas, which are only dif covered in profound excavations. But, towards the fouth, we find the islands of Ifchia, of Procida, and the whole territory from Cuma to Naples, rough with craters, and fuming with exhalations; and near these half-extinct remains, we find the formi dable Vefuvius reiling from the work of defolation, and concentrating his energies for another overwhelming explosion.

Of more than two hundred authors, who have written on the volcanic productions of the kingdom of Naples, very few have been guided in their inveftigations by fcientific views. Affected by the confternation and furprife, which phænomena fo tremendous and extraordinary naturally excite, they have endeavoured to transfufe into the minds of their readers the feelings which overpowered themfelves, and tried to make amends for the inaccu racy of their defcriptions by vague exaggeration and magnificent miftatement. Nothing in the neighbourhood of a volcano was to be explained in an obvious or ordinary manner; clouds of dust were tranflated into fmoke, fragments of pumice into ignited rocks; and fhowers of rain, with the fubfequent troubled ftreams which furrowed the mountain, were magnified into mud lavas, or into difgorged torrents of water, which were boiling hot, or falt, or both, according to the caprice of the narrator. Thefe awful operations of nature were eagerly feized on by the priests, as a certain mode of obtaining afcendancy over the minds of the bigotted populace; and the members of the celeftial hierarchy were promoted or degraded, as their votaries deemed them capable of controuling the fury of the dreaded volcano *.

Even thofe who ftudied the mountain with calmer attention, were betrayed, by preconceived opinions, into the moft extraor dinary mistakes. The Pure della Torre, with fingular perverfion of obfervation, fays, + that Vefuvius is not a mountain produced by an eruption, or formed little by little, but made of ftrata of different

*See Breiflac, vol. I. p. 225, note.

Storia è fenomeni del Vefuvio, p. 23.

different matters like all other mountains, and confumed by perpetual fire, which it contains within its bowels. He alfo ob ferves, that in the interior rocks of the Somma, and of Ottajano, no veftiges of fire are to be feen.' Though free from all fuch errors, the magnificent work of Sir William Hamilton on the Campi Phlegraci, decorated with fplendid engravings, is rather calculated to give an idea of the fcenery of the district, and the picturefque effect and character of the volcano, than to be a vehicle of fcientific information. The works of the Abbate Botis, and the Gabinetto del Vefuvio, by the Duke della Torre, contain many valuable obfervations, and curious details; but it was not till Gioeni's book, on the lithology of Vefuvius, † made its appearance, that any general and accurate defcription of Vefuvian fubftances was given.

This intelligent obferver has prefaced his defcriptive catalogue by preliminary remarks of confiderable merit, and has interfperfed notes from which much important information may be gleaned; but he has attended too much to the diverfities of individual fpecimens, and too little to general formations. In volcanoes, each eruption forms an epocha; and it is only by feparating the products of one eruption from thofe of another, and by noting the attendant phænomena, that we can register their hiftory, or reafon on their operations. Gioeni only incidentally contrafts the peculiarities obfervable in lavas of different antiquities; and his obfervations are confined to Vefuvius, where indeed he found diverfity enough to occupy him. The confideration of that fingle mountain, however, is not enough; and the examination of its ifolated products can only be confidered as establishing a partial ftandard of comparifon for the fubitances afforded by the whole extent of the volcanic diftrict, of which it forms a fmall part. An inveftigation of the phyfical conftitu-tion of the Campania, was effential to the correction and enlargement of our ideas refpecting Vefuvius itself; and for its accomplishment we muft ever hold ourfelves indebted to the indefatigable perfeverance and fagacious refearches of Scipio Breiflac.

The first edition of this work was printed in Italian, at Florence, in 1798. It has been increated by numerous fubfequent obfervations, and fome new maps. The tranflation into French has been performed-by-General Pommereuil, who has taken no Imall pains in its naturalization. The Italian measures of Breif

1791.

Published at Naples in 1776.

lac

Saggio di Litologia Vefuviana dal-Cav. Guifeppe Gioeni. Napoli,

lac have been tranfmuted into French metres, which arrogantly figure in the text, while the original expreffion is degraded to the notes. Many of Breillac's appreciations of distance, where perfect accuracy was not intended, and could not be attained, founded very well as leagues or miles, but are perfectly ridicu lous when reduced to kilometres, hectometres, metres, and centimetres. This pretended precifion would be only abfurd, if it were correctly founded upon the original; but it frequently appears, that the General gives his kilometres in round numbers, when the true converfion of his author would have afford ed a fraction. Dates, of course, are rendered conformable to the Republican kalendar; and even the nomenclature of minerals has not efcaped. The denominations invented by Haüy are familiarly introduced into the text; and the names by which the fubftances had been previously distinguished, and by which alone they are ftill known to nine tenths of the mineralogists of Europe, are termed ci-devant. We can hardly fuppofe it was modefty that induced the General to afford his readers no mode of distinguishing his notes from those of the author, except the internal evidence arifing from the diverfity of their ftyle and matter. To readers of ordinary difcrimination, however, this teft is fufficient; for no diftinctions can be more marked, than between fagacious obfervation and frivolous impertinence.

It is far from being our intention to follow the author through the whole extent of his laborious investigations, because we are fully convinced of his accuracy in obferving, and his fidelity inreporting; but we fhall beftow a few fentences on the eruption of 1794, because it prefents fome of the most striking volcanic phænomena, and serves to correct fome former errors.

On the evening of the 15th of June 1794, after fome preliminary fhocks, the bafe of the cone of Vefuvius opened to the weft, and a torrent of lava gufhed out. Five fmall craters were formed in its course, and ejected highly ignited stones with violence and in rapid fucceffion. The lava in fix hours flowed three miles, and, after deftroying the town of Torre del Greco, ran 362 feet into the fea*. The fudden cooling it there underwent, did not affect its texture, or render it prifmatic. This lava is of an earthy grain, uneven fracture, and variable porofity.

Sir William Hamilton fays, that according to the measurement of the Duke della Torre, the new promontory which the lava formed was 1204 English feet broad; its height above the fea was 12 feet, and as many feet under the water; fo that its whole height was 24 feet. It extended into the sea 625 feet. See Phil. Tranf. for 1795, P. 73,

porofity. It will ftrike fire with fteel, and is of a dark grey colour. It abounds in green augites, and contains mica rarely. It is faid to have formed augites by fublimation on the walls of the church at Torre del Greco. Glafs was converted by it into Reaumur's porcelain. Iron was generally oxidated, rarely combined with fulphur. Copper was foftened and oxidated; filver was fufed. Whilft the lava continued to flow from the western base of the cone, another opening was formed on the eaftern fide, at a rather lefs elevation, and a stream of lava iffued from it, and flowed fluggishly near a mile. On the morning of the 16th, the lava ceafed to flow from the western opening, and the mouth of the volcano refumed its activity. It remained for four days covered by a cloud of afhes which it ejected, and which fhowered over the adjacent country, and fell on an average 14 inches thick. At Caferta, more than ten miles from Vefuvius, torches were obliged to be ufed at mid-day, and the gloom was only broken by the frequent flashes of lightning which partially difplayed the mountain.

On the 20th ashes ceafed to fail, and Vefuvius became again vifible; but during the preceding convulfion, part of its fummit had fallen in, and the crater was confiderably enlarged. It now ejected, violently, vaft numbers of ftones; and denfe clouds iffued from it in continual fucceffion, and afcended to feveral times the height of the mountain, dilating as they rofe. Thefe clouds feemed chiefly compofed of minute fragments of lava, pumice, &c. Thefe phenomena continued till the 5th of July; and during that period, every cloud that appeared on the horizon was attracted to Vefuvius. Violent rains, mixing with the loofe ashes, formed impetuous torrents of thin mud, which carried devaftation everywhere. Exhalations of carbo nic acid mixed with azote, and fome fulphureous acid, infefted the cellars of Portici and Refina, and diffufed themselves over particular diftricts of the country, where they were equally fa tal to animal and vegetable life t. The vapours emitted by the volcano, during this eruption, were chiefly muriatic acid, and the muriates of foda and ammonia were abundant in the hollows of the lava. Sulphur and fulphureous acid were of rare occurrence, though the lava fometimes contained the fulphates of iron and lime; it alfo contained the oxides of iron and arfenic. The humid vapours, exhaled by the lava, rapidly formed thin filicious ftalactites, by which, near the new craters, fragments of pumice and afhes were agglutinated.

We

Olives and pear-trees alone were exempted from the evil effects of

this Scourge. See Breiflac, vol. I. p. 221.