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 anding, 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 Ramsdeus 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 6tood constantly at twenty-four, but when set on the ground, rese 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 atones, partly melted by the fire. Several sorts of pumice stones were founa on it, among which was one with some Mtlphur. 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 re move 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.