Within the last hundred years the crater has been five times wholly altered, in consequence of its interior having been completely blown out, and its walls having crumbled down. When Sir William Hamilton ascended the mountain in 1756, it had no less than three craters and cones, one within another. The outermost was a very wide-mouthed cone. Within it rose centrically another, smaller in size and narrower in the mouth; and within that again was the third and highest, having a smaller base and still narrower opening at the top, whence the greatest volume of vapour ascended. In 1767 this innermost cone merged in the second, which was greatly enlarged; and by a subsequent eruption the interval between the first and second was obliterated, so that only a single cone remained. In 1822 the whole interior of the cone was blown out, and its walls crumbled down, so as to lower the height of the mountain several hundred feet. But within the vast gulf, nearly a mile in diameter, which was thus left yawning open, there soon began to be formed a new cone, which showed itself erelong above the jagged edge of the crater. Eventually this cone increased, by the accumulation of ejected matters, to such an extent as to obliterate the division between it and the rim of the former crater—thus once more establishing a continuous cone. Since that time, the cone and crater have twice undergone similar changes.
The most usual appearance of the crater, when in comparative repose, is that of a vast circular or oval hollow basin, with nearly perpendicular walls, broken in their continuity, every here and there, by large projecting dykes, formed by the injection of more recent lavas into fissures rent in those which had previously become consolidated. Below the perpendicular walls is a rapid slope, composed of fine ashes or sand, descending to the floor of the crater, which is, for the most part, nearly flat. It is much rent by fissures, which during the night are seen to glow with a ruddy glare, emanating from the hot materials beneath, and giving to the floor the appearance of being overspread with a fiery tissue, like a spider's web. From the bottom there usually rise one or two small craters of eruption, whence continually issue sulphurous fumes, and which, at pretty regular intervals, discharge showers of stones heated to whiteness.
The exterior of the cone is composed entirely of loose cinders, ashes, and stones, so that the ascent is very laborious. The region of the mountain beneath the cone presents no difficulties, and that part of the ascent may be performed on donkeys or mules. The view from the top is magnificent. The contrast between the desolate aspect of the interior of the crater, and the smiling prospect which may be seen from its edge, has been well compared to looking out of Tartarus into Paradise.
Near Puzzuoli, in the Bay of Baiæ, and not far from Monte Nuovo, stand the ruins of the Temple of Serapis, so interesting to geologists. These remains, consisting chiefly of the shafts of three marble columns, still erect, though with a slight inclination sea-ward, afford distinct proofs, confirmed by other phenomena in the neighbourhood, that, since the beginning of the Christian era, the level of the coast in relation to that of the sea has changed twice—the land having first sunk and been then raised again, each time to the extent of upwards of 20 feet. The evidence of the submergence of the pillars consists mainly of a zone commencing at the height of about 12 feet above their pedestals, and extending 9 feet upwards, in which are numerous perforations, made by a marine bivalve mollusc. The upraising again of the ground on which the temple stands, to nearly its original height, appears to have occurred about the time of the formation of Monte Nuovo.
CHAPTER IV.
Mount Etna—Its Appearance and Height-Ancient Eruptions-Pindar's Allusion—Virgil's Description—Subordinate Cones and Craters—Caverns—Val del Bove—Formation of Monti Rossi—Eruption of 1852—Whirlwinds—Lava Torrents—Cascades of Lava—Description of Crater —Empedocles—Enceladus—Craters of 1865-Cyclopean Isles—Homer's Legend-Volcanic Origin—Other Basaltic Groups
Mount Etna may well be called the Queen of European Volcanoes, so majestic does she look, with her lofty summit glistening in the sunbeams white with snow, yet pouring forth volumes of vapour. This mountain, as you will observe from the annexed woodcut, is altogether more massive in its appearance than Vesuvius. It is about three times higher, rising to nearly eleven thousand feet above the level of the sea, and it has a circuit of about eighty-seven miles at its base.
Etna has been a volcano from time immemorial; but of its more ancient eruptions only vague traditions have survived. The Greek poet Pindar is the earliest writer who makes mention of its activity. He refers to it in his first Pythian Ode, Strophe B, 1. 1. The passage is thus rendered by Carey—
"From whose caverned depths aspire,
In purest folds upwreathing, tost
Fountains of approachless fire—
by day a flood of smouldering smoke
With sullen gleam the torrents pour"
[Illustration: Mount Etna.]