ed a small hill, composed of ancient volcanic matter, in order to observe the slow and gradual manner in which a current of liquid fire advanced from Etna. This current was two and a half miles broad; and, while he stood observing it, two small threads of lava, issuing from a crevice, detached themselves from the main stream, and approached rapidly towards the eminence where he and his guide were standing. They had only just time to escape, when they saw the hill on which they had stood a few minutes before, and which was fifty feet high, entirely surrounded, and, in about fifteen minutes, entirely melted down into the burning mass, so as to be incorporated with, and move on along with it.

Discovery of Ice on Mount Etna. A remarkable discovery of a great mass of ice on Mount Etna was made in 1828. In that year, in consequence of the protracted heat of the season, the supplies of ice at Catania and the adjoining parts of Sicily, failed entirely, and the people suffered considerably for the want of an article, considered as necessary to health as well as comfort in that hot climate.

In this dilemma, the magistrates of Catania directed search to be made for some crevice or natural grotto, on Mount Etna, where drift snow might possibly still be preserved. During this search it was discovered that near the base of the highest cone there lay a vast mass of ice, covered by a lava current. At what period this current was emitted is unknown, nor can it be conjectured what proportion of the ice was melted by the burning matter, but it appears that nothing but the flowing of the lava over this glacier, can account for its preservation.

A large number of workmen were immediately employed to quarry this ice for the use of the Catanians; but, it is said, that its hardness rendered the expense of obtaining it so great, that there is no probability of a similar undertaking, unless under similar circumstances.

VOLCANOES IN ICELAND.

Iceland is both a volcanic country, and a country of volA considerable proportion of its surface is cov

canoes.

ered with ancient or modern lava, and it is now subject to the most terrible calamities from this source.

With the exception of Etna and Vesuvius, the most complete chronological records of volcanic eruptions are those of Iceland. From these it is ascertained, that from the 12th century, there has never been an interval of more than 40 years, and rarely more than twenty, without eruptions and earthquakes in some part of that country. Single eruptions of Mount Hecla have sometimes continued for six years. In many instances the whole island has been convulsed by earthquakes, during which mountains were rent asunder, hills sunk down, and rivers have deserted their former channels.

Eruption of Skaptar Jokul. In 1783, this volcanic mountain suffered one of the most extraordinary eruptions recorded in history, both with respect to the quantity of lava it threw out, and the calamities it occasioned.

The river Skapta, a considerable stream, was for a time, completely dried, by a torrent of liquid fire from this mountain. This river was about 200 feet broad, and its banks from four to six hundred above the level of the water. This defile was not only entirely filled to a considerable extent by the lava, but it also crossed the river by the dam thus formed, and overflowed the country beyond, where it filled a lake of considerable extent, and great depth.

This eruption commenced on the 11th of June, and on the 18th of the same month, a still greater quantity of lava rushed from the mouth of the volcano, and flowed with amazing rapidity, sometimes over the first stream, but generally in a new course. The melted matter having crossed some of the tributary streams of the Skapta, completely dammed up their waters, and caused great destruction of property and lives by their overflow. The lava, after flowing for several days, was precipitated down a tremendous cataract, called Stapafoss, where it filled a profound abyss, which that great water-fall had been excavating for ages, and thence the fiery flood continued its

course.

On the third of August, a new eruption poured forth fresh floods of lava, which taking a different direction... from the others, filled the bed of another river, by which

a large lake was formed, and much property and many lives destroyed.

The effects of this dreadful calamity may in some measure be imagined, when it is known, that although Iceland did not, at that time, contain more than fifty thousand inhabitants, there perished nine thousand human beings by this single eruption, making nearly one in five of the whole population. Part of them were destroyed by the burning lava itself, some by drowning, others by noxious vapors which the lava emitted, and others in consequence of the famine, caused by the showers of ashes which covered a great proportion of the island, and destroyed the vegetation. The fish also, on which the inhabitants depended, in a great measure for food, entirely deserted the coast.

The quantity of lava which Skaptar Jokul emitted during this eruption, was greater than is recorded of any other volcano. The two principal branches or streams of lava, flowed chiefly in different directions. The length of the smallest was forty miles, and of the other fifty miles. The breadth of that branch which filled the Skapta, was from twelve to fifteen miles, and the other about seven miles. The ordinary depth of each was about 100 feet, but in narrow defiles it was more than 600 feet deep, and in many places from 200 to 300.

Allowing that the united breadth of this vast lava stream, was 20 miles, and the whole length 90 miles, then this mountain, at a single eruption, threw out a quantity of lava which covered a surface of 1800 square miles, an area equal to the fourth part of the State of Connecticut, and nearly one half the size of Rhode Island.

When it is considered that the depth of the whole might average 150 feet, we may go into calculations concerning the quantity of matter thrown out, but we can have no conception of the force required to elevate such a stream of melted rock through the crust of the earth.

Eruption of Jorullo, in 1759. Jorullo is situated in the interior of Mexico, about 100 miles from the nearest sea. This mountain, as already stated, affords the only known instance of a volcano, at a distance from some ocean. also affords an instance of the production of a new volcanic mountain, within the memory of man.

It

In June, 1759, subterranean sounds of an alarming kind were heard by the inhabitants of this district, and these were followed by earthquakes, which succeeded each other for two months. In the month of September, flames were seen to issue from fissures in the ground, and from the same place, red hot rocks were thrown to an immense height. Soon after, six volcanic cones were formed of lava and the fragments of rock, thrown up from the earth, in the same neighborhood. The least of these was three hundred feet in height. In the midst of these cones, rose Jorullo, which was formed in the same manner, and soon rose to the height of 1600 feet by the accumulation of lava and fragments of rock. The small cones ceasing their action, Jorullo became the great outlet of volcanic matter, and continued to emit lava and large fragments of primitive rock, for many months. Jorullo has continued to emit flames ever since its formation.

Volcano of Sumbawa. Sumbawa is one of the Molucca Islands; and the mountain from which occurred, on some accounts, the most extraordinary volcanic eruption of which any acconnts have been recorded, is called Tomboro.

This eruption commenced on the 5th of April, 1815, but was most terrific on the 11th and 12th of that month, nor did it cease entirely, until sometime in the following July. The explosions so much resembled the firing of heavy cannon at a distance, that the people of many vessels at sea, supposed there was a great naval engagement within hearing, but could not imagine what nations were engaged.

The commanders of some ships, and of several English forts, gave orders to prepare for battle, though they were several hundred miles distant from the mountain. At Sumatra, these tremendous explosions were distinctly heard, though not nearer than 900 miles from Tomboro. They were also heard at Ternate, in the opposite direction from Sumatra, at the distance of 720 miles from the mountain.

So immense in quantity, was the fall of ashes, that at Bima, forty miles from the mountain, the roof of the English Resident's house was crushed by the weight, and many other houses in the same town were rendered uninhabitable from the same cause. At Java, 300 miles distant, the air was so full of ashes, that from this cause, at mid day, it is said the darkness was so profound, that nothing like

it had ever before been experienced, during the most stormy night.

Along the coast of Sumbawa, the sea was covered with floating lava, intermixed with trees and timber, so that it was difficult for vessels to sail through the mass. Some captains, though at a long distance at sea, mistook this mass for land, and sent out their boats in order to ascertain the safety of their situations. The sea, on this and the neighboring coasts, rose suddenly to the height of twelve feet, in the form of immense waves, and as they retired, swept away trees, timber, and houses with their inhabitants. All the vessels lying near the shore, were torn from their anchorings, and cast upon the land. Violent whirlwinds carried into the air men, horses, cattle, trees, and whatever else was in the vicinity of the mountain. Large trees were torn up by the roots, and carried into the sea. But the most calamitous part of the account still remains; for such were the tremendous effects of the burning lava; the overflowing of the sea; the fall of houses; and the violence of the whirlwind, that out of 12,000 inhabitants on this island, only twenty six individuals escaped with their lives, all the rest being destroyed in one way or another.

The whole island was completely covered with ashes, or other volcanic matter. In some places, the bottom of the sea was so elevated, as to make shoals, where there was deep water before; and in others, the land sunk down, and was overflown by the sea.

The details of this awful calamity were collected, and published by Sir Stamford Raffles, then Governor of Java, who required all the residents in the various districts under his authority, to send him a statement of the circumstances which fell under their several observations.-See Raffles' Hist. of Java; and Brande's Quart. Jour. vol. i.

EARTHQUAKES.

Having thus given a short history of a sufficient number of volcanic eruptions, to acquaint the geological student with the phenomena, and of the tremendous as well as calamitous effects of these mighty agents, we will next refer to the subject of earthquakes, as resulting from the

same cause.