incumbent earth and rocks into the shape of a cone, or inverted funnel, and discharging itself from the crater, or aperture which it makes at the top, into the surrounding atmosphere, and over the adjacent country. This general theory will apply to all volcanoes; not excepting those in which the combustible matter, when unable to find its way to the top, or previous crater, of a dorinant volcano, forms an aperture in the weakest part of the side or base of the mountain, and thence flows into the sea or otherwise.

Extinct volcanoes are generally found at a considerable distance from the sea*; whilst those that are most active are in its immediate vicinity; and many of them are actually submarine, or situated in the very bed of the ocean. When a volcano bursts beneath the waters of the sea, the substances thrown up often rise above the surface, forming rocks and islands: such has been the case throughout every ocean on the globe. The Azores, Santorini, and Stromboli, are islands of this description, as well as Sulphur Island in the Japanese sea; but sometimes these newly-formed isles, not possessing a sufficiently firm base to support them, give way and disappear very soon after their birth. This has been the case in our time with the island of Sabrina, and with the small islet which lately arose on the coast of Sicily.

The combustible matter which causes eruptions does not appear to be universally diffused throughout the earth, but is collected in particular spots, districts, or regions, and disposed in beds or veins of smaller or greater dimensions, since volcanoes appear either in groups, or in lengthened ranges, or extended lines. Thus, Iceland and its neighbourhood presents one group; whilst the Andes of America form a lengthened range of volcanic action. Although the subterraneous connexion of the several members of any group or line is sufficiently evident; it does not follow that ignition should take place in all at once: on the contrary, eruption probably takes place only in that part of the vein or bed, which undergoes chemical decomposition from the causes before stated; consequently, one volcanic crater of a group or line will be in a state of igneous activity, whilst the others lie dormant, or have become entirely extinct.

VOLCANOES OF THE MEDITERRANEAN†. THIS Volcanic region may be divided into three provinces, viz. the district around NAPLES; SICILY, and its ISLES; and the GREEK ARCHIPELAGO. The Neapolitan volcanoes extend from MOUNT VESUVIUS or SOMMA, through the PHLEGREAN FIELDS, to the islands of PROCIDA and ISCHIA; and within this space, the volcanic force is sometimes developed in eruptions from a considerable number of points; but the greater part of its action, since the commencement of the Christian era, has been confined to one principal and habitual vent, MOUNT VESUVIUS.

THE ISLES OF ISCHIA AND PROCIDA,

poured forth by an eruption from Ischia. So violent indeed, were the earthquakes and volcanic explosions to which Ischia was subject, that the fabulous Giant, Typhon, ("from whose eyes and mouth, fire proceeded, and who hurled stones to heaven, with a loud and hollow noise,") was said to lie buried beneath it! Its present circumference is eighteen miles, its length five, and its breadth three. Several Greek and other colonies which settled on it, were compelled to abandon it on account of the violence of the eruptions, earthquakes, and burning exhalations.

Strabo, after Timæus, informs us, that a little before the time of the latter, Epomeo, or St. Nicolo, the principal mountain in the centre of the isle, vomited fire during great earthquakes; that the land between it and the coast had ejected much fiery matter, which flowed into the sea; and that the sea receded to a great distance, and then returning, overflowed the island. This eruption is supposed to have been that which formed the crater of Monte Corvo, on one of the higher flanks of Epomeo, above Foria; the lava-current of which may still be traced, by the scoria on its surface, from the crater to the sea.

To a subsequent eruption in the lower-parts of the isle, which caused the expulsion of the first Greek colony, Monte Rotaro has been attributed, and it bears every mark of recent origin; the cone is remarkably perfect, and the crater on its summit resembles that of Monte Nuovo, near Naples; but the hill itself is larger, and has given vent to a lava-stream at its base instead of its summit. It is covered with the arbutus and other beautiful evergreens ; and such is the fertility of the virgin soil, that the shrubs have almost become trees; indeed the growth of some of the smaller wild plants has been so vigorous, that botanists have had some difficulty in recognising the species. An eruption, whereby a Syracusan colony, planted by King Hiero, was dislodged, is supposed to have given rise to that mighty current of lava which forms the promontory of Zaro and Caruso. The surface of these lavas is still very arid and bristling, and covered with black cinders; so that it must have cost much labour to redeem those spots which have been converted into vineyards *.

From the period of the great eruption last mentioned, down to the present time, Ischia has enjoyed tranquillity, with the exception of one eruption of lava from Campo del Arso, in the early part of the fourteenth century, which occasioned considerable local damage.

Epomeo, the central mountain already spoken of, is 2605 feet above the level of the sea; and is composed of greenish hardened earth of great thickness, mixed in some parts with layers of marl, and streams of hardened lava.

Both these mountains, like the greater portion of those in the Terra di Lavoro, had their origin under water; although it has frequently happened to them, as to Epomeo, that after being elevated above the level of the sea, fresh eruptions have broken through, at various points. There are on different parts of Mount Epomeo, or scattered over the lower tracts of Ischia, twelve considerable volcanic cones, which have been thrown up since the island itself was raised from the bottom of the sea; and many streams of

del Arso, not far from the town of Ischia, in 1302, withduring ages previous to the remotest traditions, have served out cones having been produced; so that this island may,

There are hundreds of instances throughout the globe, where evident marks are to be found, to demonstrate that, during volcanic action, the sea has either receded from the theatre of agitation, and been partly ingulfed by some submarine abyss; or that the land, to a great extent round a volcanic crater, has been upheaved by subterranean turmoil, to so great a height as to leave the ocean's waves at an immense distance. As an example of these phenomena, we shall instance Mount Bolca, in Italy, which is situated about twenty miles north-east from Verona: the surrounding districts bear evident marks of volcanic action in a former age, as well as of having been at one time covered by the sea; although now, it appears entirely destitute of igneous energy, and lies at the distance of at least fifty miles from the nearest shore. Plants, shells, land and marine animals, leaves, birds, and insects, are found deposited in this mountain, in almost every direction; sometimes in separate beds, and at others, combined with productions which are obviously of volcanic origin. Nay, what is still more extraordinary, is the fact that most of the rivers, seas, and climates of the globe, seem to have contributed to the natural stores of Mount Bolca: for petrified fishes of Europe, Asia, Africa, and America, are found imbedded in large masses of rock of this extraordinary mountain, which is more than 1000 feet above the present level of the sea.

as a safety-valve to the whole Terra di Lavoro, whilst the fires of VESUVIUS lay dormant.

MOUNT VESUVIUS.

FROM the earliest colonization of Italy by the Greeks, until the year 79 of the Christian era, Vesuvius offered no further indications of a volcanic character than such as might be inferred, from the similarity of its structure to that of other extinct volcanoes, and the ancient lava-beds on its sides. The ancient cone was of a regular form; with a flat summit, on which the remains of a crater of former days (nearly filled up,) had left a slight depression: the sides of the interior were covered with wild vines, and the bottom was a mere barren plain. On the exterior, the flanks of the mountain consisted of fertile fields, which were richly cultivated; and at the base were situated, together with many others, the populous and flourishing cities of Herculaneum and Pompeii.

The first symptom of revival of the energies of Vesuvius, was an earthquake, in the year 63 of the Christian era, which did considerable injury to the cities in its vicinity; from which time, until 79, there were several slight shocks. In the month of August of the latter year, these became more numerous and violent; and at length, a tremendous eruption showed that the volcanic fire of this region had been recalled to the main channel.

The elder Pliny, who held the command of the Roman fleet, stationed at Misenum, a cape or headland about twice the distance westward from the volcano, as the city of Naples, in his anxiety to obtain a nearer view of the phenomenon, fell a victim to the sulphureous vapours. The younger Pliny, his nephew, who remained with the fleet at Misenum, has left us a very lively description of the awful scene in his Letters. He says, that a dense column of vapour was first seen arising vertically from Vesuvius; and then spreading itself out laterally, so as to resemble the head and trunk of the Italian pine-tree. This black cloud was occasionally pierced by flashes of fire as vivid as lightning; and the whole atmosphere suddenly became darker than night. The eruption had commenced with such amazing force, that ashes fell even upon the ships at Misenum; indeed they fell in such quantities as to cause a shoal in one part of the sea! In the mean time, the ground rocked terribly; and the sea receded so far from the shores, that many marine animals were left exposed on the dry sand. These appearances agree exactly with those witnessed in more recent volcanic eruptions; particularly that of Vesuvius in 1822: indeed, in all times and countries, there is a striking uniformity in volcanic phenomena.

It does not appear that in 79 any lava flowed from Vesuvius: the ejected substances consisted of lapilli, sand, and fragments of rock and ancient hardened lava; so that it is erroneous to suppose that Herculaneum and Pompeii were overwhelmed with streams of burning lava. These cities, as the excavations have since proved, were buried under showers of ashes. Neither is it true, that all the inhabitants were buried alive as they sat in the theatres, as Dion Cassius the historian states; for during years of examination, comparatively but a few mortal remains have been discovered in the theatres, the temples, the streets, or the houses many lives, no doubt, were lost; but, the shower of ashes and other matter being of long continuance, the inhabitants generally had sufficient time to escape.

The first stream of lava which flowed from Vesuvius, of which we have any account, was in the year 1036, this being the seventh volcanic eruption since the revival of its action. Two other eruptions took place in 1049 and 1138. During the interval of 168 years of repose, which followed the latter period, two minor vents of this volcanic range opened at distant points; viz. that of the Solfatara, in 1198; and that of Campo del Arso in Ischia, in 1302. The next eruption of Vesuvius was in 1306; and there was a slight one in 1500. Between the former period, and the year 1631, there was a pause in its energies; but Mount Etna, in the island of Sicily, was in such a state of activity as to warrant the conclusion that the latter volcano sometimes serves as a channel to discharge those elastic fluids and lava, which would otherwise be ejected in the south of Italy.

This great pause in the eruptive action of Vesuvius was also marked by a memorable event in the Phlegræan Fields; and by the sudden formation of a new mountain near Naples, in 1538. During nearly a century after the birth of the latter, Vesuvius still remained in a state of quiescence; there having been no violent eruption during 492 years. It appears that the crater was then in exactly the same condition as the (at present) extinct volcano of Astroni, near Naples.

Braccini, who visited Vesuvius not long before the eruption of 1631, gives this interesting description of its interior:-"The crater was five miles in circumference, and about 1000 paces deep; its sides were covered with brushwood, and at the bottom there was a green plain, on which cattle grazed. In the woody parts, wild boars frequently harboured; and, in one part of the plain, covered with ashes, there were three small pools; one, filled with hot and bitter water; another, salter than the sea; and the third, hot but tasteless." In December, 1631, however, these verdant plains and woods, with their wild boars and other inhabitants, were consumed. Seven streams of lava poured at once from the crater, and overflowed several villages at the foot of the mountain. The city of Resina, which had been partly built over the ancient city of Herculaneum, was consumed by the fiery torrent. Great floods of mud, also, or torrents of water ejected from the crater, and mixing with the ashes, were as destructive as the lava itself.

Vesuvius had now a brief repose of thirty-five years: viz., until 1666; since which time, until the present, there has been a constant series of eruptions, with rarely an interval of rest during ten years together. During the last two centuries, however, no irregular volcanic agency has convulsed other points in this district.

It has been remarked, that such irregular convulsions had occurred in the bay of Naples, in every second century; for example, the eruption of the Solfatara, in the 12th; of the lava of Campo del Arso, in the 14th; and of Monte Nuovo, in the 16th; but the 18th century appears to be an exception to this rule; which is to be accounted for by the unprecedented number of eruptions during that period whenever new vents have opened, there has always been a long intermission of activity in the principal volcano. THE CONE Of Vesuvius. the crater of Mount Vesuvius had been gradually filling DURING upwards of one hundred years previously to 1822 up by lava boiling from below, as well as by scoriæ falling from the explosions of smaller mouths, which were formed at intervals on its base and sides: instead of a regular cavity, therefore, the crater was an enclosed rocky plain, covered with blocks of lava and cinders, and traversed by numerous fissures, from which clouds of vapour were continually rising.

In October, 1822, violent explosions, during an eruption of more than twenty days, broke up and threw out all this accumulated mass; leaving an immense chasm or gulf of an irregular shape, somewhat resembling an oval, about three miles in circumference, but rather less than three-fourths of a mile in diameter.

The depth of this tremendous abyss has been variously estimated; for from the period of its formation, it has decreased daily by the falling away of its sides: at first, the depth was said to be 2000 feet from the summit; but, after the eruption of 1822, the same was estimated at less than 1000; indeed, more than 800 feet of the cone had been carried away by the explosions, so that not only was the depth of the crater made smaller, but the mountain itself was reduced in height from 4200 feet, to 3400.

NOCTURNAL VIEW OF AN ERUPTION OF VESUVIUS. A LATE traveller, who made one of a party to visit Vesuvius by night, thus describes the phenomena of an ordinary eruption: "It was about half-past ten when we reached the foot of the craters, which were both tremendously agitated; the Great Mouth threw up immense columns of fire, shrouded in the blackest smoke, mixed with sand, which filled our eyes and ears. Each explosion of fire was preceded by a bellowing of thunder in the mountain. The smaller mouth was much more active; and the explosions followed each other so rapidly, that we could not count three seconds between them. The stones which were emitted were fourteen seconds in falling back to the crater; consequently, there were always five or six explosions— sometimes more than twenty-in the air at once. These stones were not thrown up perpendicularly, in the shape of a pillar of fire, as from the other crater, but in that of a widespreading sheaf, producing the most magnificent effect imaginable. The smallest stones appeared of the size of cannon-balls; the greater number were like bomb-shells; but others were pieces of rock, five or six cubic feet in size. and some of most enormous dimensions: the latter generally fell on the ridge of the crater, and rolled down its sides, splitting into fragments as they struck against the hard and cutting masses of cold lava. Some of these stones, even when on fire, are extremely hard, but the larger ones are a complete paste of fire, and whilst at a red heat are easily

MOUNT ETNA

Is situated in the island of Sicily. It is very nearly 11,000 feet, or upwards of two miles, above the level of the sea; and on a clear day may be distinctly seen from the island of Malta, which is 150 miles off. It is by far the largest burning mountain in Europe; and, from its sides, other mountains arise, which have, in different ages, been thrown out in single masses.

The most extensive lavas of Vesuvius do not exceed seven miles in length; whilst those of Etna extend to fifteen, twenty, and sometimes even thirty miles: the crater is seldom less than a mile in circuit, and is sometimes two or three miles.

A journey up the sides of Etna is generally considered an enterprise of importance; not only from the difficulty of the route, but on account of the distance, which is thirty miles from the city of Catania to the summit. Its gigantic bulk, its sublime elevation, and the extensive, varied, and grand prospects which are presented from its top, have, however, induced the curious, in every age, to ascend and examine it. It has been divided into three distinct regions. The cultivated region, which extends twelve miles upwards from the base, contains beautiful pastures, vines, and fruittrees in abundance, besides towns, villages, and monasteries. The woody or temperate region is mild and pleasant; its turf is covered with aromatic plants, and the gulfs which formerly threw out torrents of fire, are now changed into woody valleys: the chesnut and the oak grow here to a prodigious size. The last, or desert region, commences about a mile from the summit; the lower part is covered with snow during the winter only; but the upper part is clothed with this fleecy garment all the year.

The cone is described by Sir W. Hamilton, and others, as a little steep mountain, about a quarter of a mile high, situated in the centre of a gently-inclined plane of about nine miles in circumference. The crater is of an oval shape, having its edges greatly indented by the projection and falling back of the lava and rocks: the bottom, like that of Vesuvius and other volcanoes, is a plain, about two thirds of a mile round; from which a column of smoke constantly issues. Within an opening in the side, may be clearly seen the liquid burning matter constantly boiling and waving, without spreading over the bottom.

Eruptions are recorded by Diodorus Siculus, to have taken place from this volcano, before the Trojan war. In the eruption of 1669, the torrent of burning lava inundated a space of fourteen miles in length, and four in breadth; burying beneath it 5000 villas and other habitations, with part of the city of Catania, and at length falling into the sea:

during several months before the lava burst out, the old mouth, or great crater, was observed to send forth much smoke and flame, and the top fell in; so that the cone became much lowered. In 1809, twelve new craters opened, about half way down the mountain, and threw out rivers of burning lava, by which several estates and farms were covered to the depth of thirty or forty feet. In 1811, several mouths opened on the eastern side; and discharged torrents of burning lava with amazing force.

The last eruption of Etna was on the 31st of October, 1832. About the middle of the night there suddenly arose, without any previous indication, a column of smoke and flame from the base of the last cone, on the northern side; and, shortly after, an immense quantity of fiery and fluid matter was discharged from the crater, on the western side, dividing itself into numerous burning streams. Next morning, repeated shocks or earthquakes, the increased noise of the lava which now flowed rapidly, and immense volumes of thick black smoke at the foot of Monte Scavo, announced that the eruption had increased greatly in violence, and several streams of lava now descended. On the 2nd of November, contrary to all expectation, the eruption ceased, and the lava was found to be so far cooled, that several adventurous observers were enabled to get upon it, and walk a few paces. On the 3rd, the hope that the fire was almost extinct was nearly certain; but, in the evening, a violent shock, followed by several smaller ones, with a fresh quantity of smoke, foretold a fresh eruption. About two hours before midnight, a severe shock occurred, which was followed by black smoke, mingled with flames, and the thunders became louder and louder every moment.

"Having approached," says Signor di Luca, (an eye-wit ness of this dreadful scene,) "as nearly as was prudent, to the hollow from which the fire issued, we found four openings, which threw out burning matter. Raising our eyes from these openings, we observed a cleft or rent, about a mile in length: from this cleft, volumes of smoke arose from time to time; and, as at the bottom it touched, as it were, the openings just mentioned, it gave us an opportunity of beholding the burning entrails of the volcano, and the great furnace in the interior of the mountain. Meanwhile, the thunder was incessant; and the detonations were often terrible: the lava continued to flow; and enormous masses of burning substances were thrown, without interruption, to a great height, mingled with vast volumes of flame and smoke. The shocks of earthquake likewise were so violent, that horses, cattle, and other animals, fled in terror from the places where they were feeding."

By the seventh of the month, the lava of the four mouths