In the year 1794, there was a very tremendous eruption, and the mischief done was very considerable: the lava covered and totally destroyed 5000 acres of rich vineyards and cultivated land, and drove the inhabitants of Torre del Greco from the town, a great part of the houses being either buried, or so injured as to be uninhabitable; the damage done in the vineyards by the ashes was also immense. Eruptions of this volcano also took place in 1804 and 1805; but this article will conclude by noticing only the eruption that happened on the evening of the 31st of May, 1806, when a bright flame rose from the mountain to the height of about 600 feet, sinking and rising alternately, and affording so clear a light, that a letter might have been read at the distance of a league round the mountain. On the following morning, without any earthquake preceding, as had been customary, the volcano began to eject inflamed substances from three new mouths, pretty near to each other, and about 650 feet from the summit. The lava took the direction of Torre del Greco and Annunciata, approaching Portici on the road leading from Naples to Pompeii.
Throughout the whole of the 2d of June, a noise was heard, resembling that of two armies engaged, when the discharges of artillery and musketry are very brisk. The current of lava now resembled a wall of glass in a state of fusion; sparks and flashes issuing from it from time to time with a powerful detonation. Vines, trees, houses, in short, whatever objects it encountered on its way, were instantly overthrown and destroyed. In one part, where it met with the resistance of a wall, it formed a cascade of fire. In a few days, Portici, Resina, and Torre del Greco, were covered with ashes thrown out by the volcano; and on the 9th, the two former places were deluged with a thick black rain, consisting of a species of mud, filled with sulphureous particles.
On the 1st of July, the ancient crater had wholly disappeared, being filled with ashes and lava, and a new one was formed in the eastern part of the mountain, about 600 feet in depth, and having about the same width at the opening. Several persons, on the above day, descended about half way down this new mouth, and remained half an hour very near the flames, admiring the spectacle presented by the liquid lava, which bubbled up at the bottom of the crater, like the fused matter in a glasshouse. This eruption continued until September, made great ravages, and was considered as one of the most terrible that occurred within the memory of the oldest inhabitants. Sir William Hamilton observes, that the inhabitants of Naples, in general, pay so little attention to the operations of this volcano, that many of its eruptions pass unnoticed by at least two-thirds of them. It is remarkable to observe, with what readiness and sang froid they inhabit the towns and villas on the brow of the mountain, and how quickly they return to spots which have suffered the most severely. The inhabitants are not much alarmed by a stream of lava, which moves slowly, from which they can always remove, and carry off their moveable property; their greatest danger consists in the clouds of burning ashes, which fly to a great distance, and the fall of which can neither be anticipated nor avoided.
Mount Hecla.—This is a volcano of Iceland, and one of those whose operations are the most powerful of any in the world. It was visited in 1722, by Dr. Van Troil, a Swedish gentleman, together with Mr. (afterwards Sir Joseph) Banks, Dr. Solander, and Dr. James Lind, of Edinburgh. On their first landing, they found a tract of land sixty or seventy miles in extent, entirely ruined by lava, which appeared to have been in the highest state of liquefaction. Having undertaken a journey to the top of the mountain, they travelled from 300 to 360 English miles, over an uninterrupted tract of lava, and had at length the pleasure of being the first who had arrived at the summit of the mountain.
Hecla, according to their accounts, is situated in the south part of the island, about four miles from the sea coast; and is divided into three parts at the top, the middle point being the highest. From an exact observation with Ramsden’s barometer, it is 5000 feet above the level of the sea. They were obliged to quit their horses at the first opening from which the fire had burst. They describe this as a place with lofty walls and high glazed cliffs, unlike any thing which they had ever seen before. A little higher up they found a large quantity of grit and stones; and still farther, another opening, which, though not deep, descended lower than that of the highest point. Here, they imagined, they plainly discerned the effects of boiling water; though not far from thence the mountain was covered with snow, excepting some spots, which difference they perceived to be occasioned by the hot vapour issuing from the crevices in the mountain. As they ascended towards the top, they found the spots become larger; and about 200 yards below the summit, a hole about a yard and a half in diameter was observed, whence issued so hot a steam, that they could not measure the degree of heat with the thermometer.
The cold began now to be very intense; Fahrenheit’s thermometer, which at the foot of the mountain was at fifty-four, now fell to twenty-four; the wind also became so violent, that they were sometimes obliged to lie down, for fear of being blown down the most dreadful precipices. On the very summit, they experienced at the same time a high degree of heat and of cold; for, in the air, Fahrenheit’s thermometer stood constantly at twenty-four, but when set on the ground, rose to 153; the barometer stood at 22.247. Though they wished very much to remain here for some time, they found that they could not effect their purpose with safety; they therefore descended quickly.
The mountain seems to be made up, not of lava, but of sand, grit, and ashes; which are thrown up with discoloured stones, partly melted by the fire. Several sorts of pumice stones were found on it, among which was one with some sulphur. Sometimes the pumice was so much burnt, that it was as light as tow. Its form and colour were sometimes very fine, but at the same time so soft, that it was difficult to remove it from one place to another. The common lava was found in both large and small pieces; as well as a quantity of black jasper, burned at the extremities, and resembling trees and branches. Some slate, of a strong red colour, was observed among the stones thrown out by the volcano. In one place the lava had taken the form of chimney-stacks half broken down.
As they descended the mountain, they observed three openings. In one, every thing looked as red as brick; from another, the lava had flowed in a stream about fifty yards broad, and, after proceeding some length, had divided into three large branches. Further on they perceived an opening, at the bottom of which was a mount in form of a sugar loaf; in throwing up of which, the fire appeared to have exhausted itself. The reason that no one before them had ever ascended to the top of this mountain, was partly owing to superstition, and partly to the steepness and difficulty of the ascent, which was in a great measure removed by an eruption in 1766.
We now proceed to describe the celebrated Mount Etna.—