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ETNA.

T

HERE is a marked contrast between the circumstances of the present eruption of Etna and those of the last. For many years the great South European volcanic system has shown but few signs of disturbance, and those only slight. Vesuvius has occasionally threatened an outbreak. The crater of that mountain has filled several times to the brim, and has once or twice overflowed; but there has been no great eruption of Vesuvius. Etna has been almost entirely quiescent for the last ten years. The other less important outlets of the South European volcanic system have been equally free from disturbance.

It was otherwise when in November 1868 Etna burst into eruption. During thirteen months the volcanic system of Southern Europe had been disturbed by subterranean movements. Scarcely a single portion of the wide area included under that name had been free from occasional shocks of earthquake. There had been shocks at Constantinople, at Bucharest, at Malta, and at Gibraltar. Mount Vesuvius, the most active though not in all respects the most important of the outlets by which that system finds relief, had been in a state of activity during the whole of the preceding year, and three several times in actual eruption. But it had seemed as though Vesuvius-owing perhaps to changes which had taken place in its subterranean ducts and conduits-had been unable to give complete relief to the forces then at work beneath the southern parts of Europe. Whenever Vesuvius had been quiescent for a while during 1868, earthquakes occurring at far distant places not only showed the connection which exists between the action of Vesuvius and the condition of regions far remote from Vesuvius, but that the great Neapolitan outlet was not able to relieve as usual the remote parts of that wide volcanic region. Even in England and Ireland there were earthquakes, at times corresponding significantly with the temporary quiescence of Vesuvius. In fact, scarcely ten days had passed after the occurrence of an earthquake which alarmed the inhabitants of Western Europe, before a great eruption of Vesuvius began. A vast cone was thrown up, from which the imprisoned fires burst forth

in rivers of molten lava; and round the base of this cone other smaller ones formed themselves which added their efforts to that of the central crater and wrought more mischief than in any eruption of Vesuvius since that of 1797.

But, enormous as was the quantity of lava which those cones poured forth, it would seem that Vesuvius was still unable to give perfect relief to the imprisoned gases and fluids which had long disturbed the South of Europe. All that Vesuvius could do had been done; the smaller cones had discharged the lava which communicated directly with them, and had then sunk to rest; the great cone alone continued-but with diminished energy-to pour forth masses of burning rock and streams of liquid lava. That the imprisoned subterranean fires had not fully found relief was shown by the occurrence of an earthquake at Bucharest, late on the evening of November 27, which was only a day after the partial cessation of the eruption of Vesuvius. Probably the masses of liquid fire which had been flowing towards Vesuvius had collected beneath the whole of that wide district which underlies Etna, Stromboli, and the Neapolitan vents. Be this as it may, it is certain that but a few hours after the occurrence of the earthquake in Wallachia Mount Etna began to show signs of activity, and by the evening of November 28, 1868, was in violent eruption.

When we consider these circumstances in connection with the recognised fact that Etna is an outlet of the same volcanic system, we can hardly be surprised that the ineffectual efforts of Vesuvius should have been followed by an eruption of the great Sicilian volcano. We can imagine that the lakes of fire which underlie the Neapolitan vent should have been inundated, so to speak, by the continual inrush of fresh matter, and that thus an overflow should have taken place into the vast caverns beneath the dome of Etna which had been partially cleared when the Sicilian mountain was in eruption in 1865. During a whole year some such process had probably been going on, until at length the forces which had been silently gathering themselves were able to overcome the resistance of the matter which stopped up the outlets of Etna, and the mountain was forced into violent and remarkably sudden action.

Unlike Vesuvius, Etna has always, within historic times, been recognised as an active volcano. Diodorus Siculus speaks of an eruption which took place before the Trojan war, and was so terrible in character as to drive away the Sicani who had peopled a neighbouring district. We learn also from Thucydides that in the sixth year of the Peloponnesian war a lava-stream destroyed the suburbs

of Catania. This eruption, says the historian, was the third which had taken place since the island had been colonised by the Greeks. Classical readers will scarcely need to be reminded of Pindar's graphic description of the eruption which took place fifty years before the one referred to by Thucydides. Although the poet only alludes to the mountain in passing, he has yet succeeded in presenting with a few skilful strokes the solemn grandeur of ancient Etna, the scene of the struggles of the buried giant Typhoeus. He portrays the snowy mountain as "the pillar of the heavens, the nurse of eternal snows, hiding within deep caverns the fountains of unapproachable fire; by day a column of eddying smoke, by night a bright and ruddy flame; while masses of burning rock roll ever with loud uproar into the sea."

The cone of Etna rises to more than twice the height of Mount Vesuvius. Of old, indeed, the Sicilians assigned to their mountain a height not falling very far short of that of the grandest of the Alpine mountains. But in 1815, Captain (the late Admiral) Smyth ascertained by a careful series of trigonometrical observations that the true height of the mountain is 10,874 feet. The Catanians were indignant that a young, and at that time undistinguished, Englishman should have ventured to deprive their mountain of nearly 2,000 feet of the height which had been assigned to it by their own observer Recupero, and they refused to accept the new measurement. Nine years later, however, Sir John Herschel from barometrical observations estimated the mountain's height at 10,872 feet. The close agreement between the two results was spoken of by Herschel-Lyell tells us-as a "happy accident;" but, as Dr. Wollaston remarked, "it was one of those accidents which would not have happened to two fools."

The figure of Etna is a somewhat flattened cone, which would be very symmetrical were it not that on the eastern side it is broken by a deep valley called the Val del Bove, which runs nearly to the summit of the mountain, and descending half-way down its banks is connected with a second and narrower valley, called the Val di Colonna. The cone is divided into three regions called the desert, the woody, and the fertile regions. The first of these is a waste of lava and scoriæ, from the centre of which uprises the great cone. The woody region encircles the desert land to a width of six or seven miles. Over this region oaks, pines, and chestnut-trees grow luxuriantly; while here and there are to be seen groves of cork and beech. Surrounding the woody region is a delightful and wellcultivated country lying upon the outskirts of the mountain and forming the fertile region. This part of Etna is well inhabited and

One of the most

thickly covered with olives, vines, and fruit-trees. singular peculiarities of the mountain is the prevalence over its flanks of a multitude of minor cones, nearly a hundred of which are to be seen in various parts of the woody and fertile regions. Of these, Sir Charles Lyell remarks, that “although they appear but trifling irregularities when viewed from a distance as subordinate parts of so imposing and colossal a mountain, they would, nevertheless, be deemed hills of considerable magnitude in almost any other region."

It has been calculated that the circumference of the cone is fully eighty-seven English miles; but that the whole district over which the lava extends has nearly twice that circuit.

Of the earlier eruptions of Mount Etna we have not received very full or satisfactory records. It is related that in 1537 the principal cone, which had been 320 feet high, was swallowed up within the hollow depths of the mountain. And again, in 1693, during the course of an earthquake which shook the whole of Sicily and destroyed no fewer than 60,000 persons, the mountain lost a large portion of its height, insomuch that, according to Boccone, it could not be seen from several parts of the Valdemone whence it had before been clearly visible. Minor cones upon the flanks of the mountain were diminished in height during other outbursts in a different manner. Thus in the great eruption of 1444, Monte Peluso was reduced to twothirds of its former height, by a vast lava-stream which encircled it on every side. Yet, though another current has recently taken the same course, the height of this minor mountain is still three or four hundred feet. There is also, says Sir Charles Lyell, "a cone called Monte Nucilla, near Nicolosi, round the base of which successive currents have flowed, and showers of ashes have fallen, since the time of history, till at last, during an eruption in 1536, the surrounding plain was so raised, that the top of the cone alone was left projecting above the general level."

But the first eruption of which we have complete and authentic records is the one which occurred in the year 1669. An earthquake had taken place by which Nicolosi, a town situated about twenty miles from the summit of Etna, was levelled to the ground. Near the site of the destroyed town two gulfs opened soon after, and from these gulfs such enormous quantities of sand and scoria were thrown out that a mountain having a double peak was formed in less than four months. But, remarkable as was the evidence thus afforded of the energy of the volcanic action which was at work beneath the flames of the mountain, a yet more striking event presently attracted the

attention of the alarmed inhabitants of the neighbouring country. On a sudden, and with a crash which resounded for miles around, a fissure, twelve miles in length, opened along the flanks of the disturbed mountain. The fissure extended nearly to the summit of Etna. It was very deep-how deep is unknown-but only six feet in width. Along its whole length there was emitted a most vivid light. Then, after a brief interval, five similar fissures opened one after another, emitting enormous volumes of smoke, and giving vent to bellowing sounds which could be heard at a distance of more than forty miles. At length the eruption commenced in earnest. The volume of lava which was poured forth was greater than any that has ever been known to flow from the mountain during historical times. According to the estimate of Ferrara, no less than 140 millions of cubic yards of lava were poured down the sides of the mountain. The current, after melting down the foundations of a hill called Mompiliere, overflowed no fewer than fourteen towns and villages, some of which had as many as three thousand and four thousand inhabitants. Alarmed at the progress of the sea of lava which threatened to overwhelm their city, the Catanians upreared a rampart of enormous strength and sixty feet in height. So stoutly was this bulwark established that the lava was unable to break it or to burn it down. The molten sea gradually accumulated, until at length it rose above the summit of the rampart, from which it poured in a fiery cascade, and destroyed the nearer part of the city. "The wall was not thrown down, however," says Sir Charles Lyell, "but was discovered long afterwards by excavations made in the rock by the Prince of Biscari; so that the traveller may now see the solid lava curling over the top of the rampart as if still in the very act of falling. The current had performed a course of fifteen miles before it entered the sea, where it was still six hundred yards broad and forty feet deep. It covered some territories in the environs of Catania, which had never before been visited by the lavas of Etna. While moving on, its surface was in general a mass of solid rock; and its mode of advancing, as is usual with lavastreams, was by the occasional fissuring of the solid walls. A gentleman of Catania, named Pappalardo, desiring to secure the city from the approach of the threatening torrent, went out with a party of fifty men whom he had dressed in skins to protect them from the heat, and armed with iron crows and hooks. They broke open one of the solid walls which flanked the current near Belpasso, and immediately forth issued a rivulet of melted matter which took the direction of Paterno; but the inhabitants of that town, being alarmed for their safety, took up arms and put a stop to further operations."