after having mentioned Lipari and Vulcano, and informed us that Stromboli likewise burns, tells us that the latter island, compared to the others, is inferior to them in the violent eruption of its flames, but that it exceeds them in their brightness.

It is evident, that by "the others," Strabo means Vulcano, which was the only one of the Eolian isles, besides Stromboli, in a state of conflagration in his time. When I compare Stromboli with Vulcano, I perceive that even now there is this difference between the two islands, that the flames of the former are much more resplendent and lively than those of the latter; but I cannot say that those of Stromboli are less violent, as the contrary is certainly the fact. We must, however, conclude, that in those ages the eruptions of Vulcano were very strong and frequent, which agrees with the testimony of Diodorus, and that of Agathocles as cited by the Scholiast on Apollonius; the former of whom asserts, that in his time Vulcano and Stromboli vomited great quantities of sand and burning stones; and the latter, that these two islands threw out fire, both by day and night.

There is another circumstance mentioned by the Sicilian historian which deserves notice. This is, that a wind issues from both these islands with a great noise. This in some measure agrees with the observations I made at Stromboli, and the attentive examiner will find it still more applicable to the other island.

Philip Cluverius, in his Sicilia Antiqua, speaking of Stromboli, tells us that its crater is situated at the summit of a mountain, from which it pours forth, both by day and by night, with a horrible noise, bright flames and great quantities of pumice. In one of the plates prefixed to his work, this island is represented with the smoke rising from the summit of the mountain.

Nearly one hundred and seventy-three years have now elapsed since this author travelled in Sicily. Ought we then to conclude, that, at that time, the mouth of the volcano was situated at the summit of the mountain? Had the learned antiquary himself visited the island, I could not have objected to his evidence. But he not only does not say this, but the contrary may be inferred from his own words. Immediately after the passage I have already cited,

◊ Strongule hodieque liquidissimam flammam, et pumices magna copia, ex vertice, ubi craterem habet noctes atque dies, cum fremitu horrendo, eructąt.

he adds, " sed perpetui ejus ignes eminus navigantibus, nocte tantum, conspiciuntur. Fumum eorum candidissimum ex Italiæ pariter ac Siciliæ littoribus conspexi." It is therefore evident that he saw this volcano only from a distance, and that, consequently, his assertion, that the fiery crater was situated at the summit, is not to be depended on. What he has said of the pumices then thrown out by it, he may have taken on the credit of some of the uatives who gave him that information, and who confounded the scoriaceous lavas with pumices; or it may in fact be true, since under the scoriæ and lavas of Stromboli, scattered pumices are found, as I have observed above.

From the authorities above adduced it appears, therefore, that the most ancient accounts of the conflagrations of Stromboli, transmitted to us by history, are prior to the Christian era by about 290 years, the date of the reign of Agathocles, the celebrated tyrant of Syracuse. This volcano burned likewise in the times of Augustus and Tiberius, when Diodorus and Strabo flourished. But after this latter period, a long series of ages succeeds, during which, from want of documents, we are ignorant of the state of Stromboli; and it is not until the seventeenth century, that we again know with certainty that it ejected fire; though it is not improbable that it continued to burn likewise during the times in which we find no mention of it in history: on which supposition, its uninterrupted conflagration, for so great a length of time, must indeed appear astonishing. Yet, though it should have ceased for several ages, we know from various public testimonies, that its continued eruptions cannot have lasted less than two hundred years.

Here our curiosity may naturally be excited by the question: what are the substances which, without diminution, have nourished, during such a number of years, and still continue to feed, these fires? I do not perceive that there is any reason to suppose them different from those which furnish fuel to the intermitting volcanoes, except that their source appears to be inexhaustible. It is believed, with much reason, that sulphur produces and continues volcanoes; and wherever these mountains burn, we have indisputable proofs of its presence. Still more effectually to explain these conflagrations, petroleum has likewise been called in aid; and, in fact, it has sometimes been found to issue in the neighbourhood of a volcano, of

which Vesuvius is an example. The clouds of thick black smoke, which frequently rise into the air from the mouths of volcanoes, and the unctuosity and sootiness which are said to be found in the recent scoriæ, seem likewise to be evident indications of some bituminous sublimate.

That Stromboli contains within its deep gulphs and recesses an immense mine of burning sulphur, we can entertain little doubt, when we consider the streams of smoke, of extraordinary whiteness (a colour which constantly accompanies sulphureous fumes), that rise on the west side of the island, and the smell of sulphur, not only perceptible from them, but from the large cloud of smoke which overhangs the summit of the mountain. The small pieces of that mineral produced near the apertures whence those fumes arise, are likewise another proof. But of the presence of petroleum, and its effects, I have never perceived the least sign. Besides that no vein of it is found in the island, nor any ever seen swimming on the sea which surrounds Stromboli, as I was assured by the general testimony of the inhabitants, the smell of this bitumen is no where sensible, though naturally it is very acute. I have frequently visited the sources of petroleum, at Monte Zibio, in the territory of Modena, and I could always perceive the smell of their penetrating vapours, at the distance of several hundred paces, before I reached them. I therefore conclude, that these vapours must have been much more sensible at Stromboli, as they would have been much more active, had petroleum actually burned within its gulph. I have likewise examined, with the greatest attention, the scoria thrown ont by the volcano, and while they were very hot; but I never could perceive that they emitted, either from their surface or within their pores and cavities, the least smell of that bituminous substance, or that they any where exhibited any unctuous humidity. As I knew that the smoke which exhales from burning petroleum is of a blackish hue, I suspected that the thick and dark column of smoke, which arose to the east of the volcano, might be a sign of its presence; but, on a nearer approach, I perceived that its darkness proceeded from aqueous vapours which were mixed with it, and which,

*Serao, Istoria dell' Incendio del Vesuvio, del 1737. Bottis, Istoria di varj Incendj del Monte Vesuvio.

by my continuing a short time in it, rendered my clothes damp and wet.

Shall we then affirm that the fires of Stromboli receive no kind of aliment from this bitumen? Notwithstanding the observations I have stated, I would not venture confidently to deduce such a conclusion; since it is possible that the petroleum may burn under the mountain, at so great a depth that its vapours may not reach to the top, but may be dispersed and consumed by the fire, and the immense mass of liquefied matter, which probably extends from the crater to the lowest roots of the islaud.

But though we should not admit the existence of this oil within the deep recesses of the mountain, I do not perceive but the sulphur alone may be sufficient for the nourishment of the volcano, when its flame is animated by oxygenous gas, the presence of which, in volcanic abysses, seems undeniable, from the substances they contain proper to generate it, when acted on by the fire. The long duration without intermission, therefore, of these conflagrations, may be very sufficiently explained by the immense quantities of sulphur, or, to speak more properly, sulphures of iron which we must necessarily suppose contained in the bowels of the mountain; a supposition rendered the more probable by the prodigious subterranean accumulations of this mineral which have been discovered in various parts of the globe.

[Spalanzani. Dolomieu, Isles Ponces.]

CHAP. XII.

VOLCANOES OF ICELAND.

SECTION 1.

Introductory Remarks.

ICELAND, perhaps the Ultima Thule of Virgil, about two hundred and sixty miles long, and two hundred broad, forming an extensive portion of the Danish dominions, evinces in every quarter a volcanic origin, and abounds in volcanoes, sulphur, subterraneous fires, and geysers, or eruptive hot springs. Its highest mountains, clothed with perpetual snows, are called Jokuls, and of these Snæfell, in the south-western part of the island, is the loftiest, being calculated at six thousand eight hundred and sixty feet above the level of the sea. Its principal rivers lie towards the east, some of which are white with lime, and others tainted with sulphur. Its calcareous spar has been celebrated ever since the days of Newton for its double refraction. This remote and barren country has been not unfrequently subject to dreadful mortalities from epidemics: the pestilence of this kind that depopulated the island, in the middle of the fourteenth century, was called the Black Death; and ac cording to Cattereau, a murrain in 1784 carried off not less than nineteen thousand four hundred and eighty-eight horses, six thousand eight hundred beeves, and twelve thousand nine hundred and forty-seven sheep. This account, however, seems too highly charged, for it exceeds the general average of the cattle of the entire island. Since it has appertained to the Danish crown, a colony endeavoured to ameliorate its wretched situation by migrating to Greenland, about two hundred miles distant, and which is now usually placed in the American quarter of the world; of its success, however, we know nothing, for the eastern coast, on which it probably effected a landing, has since been so extensively blocked up by aug menting sheets of ice, that the colony has never since been explored. -Yet to this wretched verge of the habitable globe was literature compelled to retire in the eleventh and twelfth centuries: here