the destruction of their houses. Those who, alarmed, beat a hasty retreat into the open country, might observe near the crest of the mountain a column of thick black smoke and burning matter which was driven into the air with great impetus and fell again, scattered by the wind, the lighter portions in the form of small scoria and sand at a considerable distance. Shortly afterwards this column appeared, to those looking from north to south, as if it became larger at the base, whilst looking from east to west there seemed to be numerous columns inclined slightly towards the north. These, like the first, consisted of thick smoke and burning matter, which in the darkness of night looked like a grand display of fireworks with a constant emission of colossal rays.

This phenomenon was at the same time accompanied by those rumblings which usually manifest themselves when the lava is about to burst forth from the earth, and lasted with great intensity for seven hours on the 29th, from 4 till 11 A.M. For the rest of that day, and during the night of the 29th, the violence of the outbreak diminished; and on Sunday the 30th its force was much weakened; and the following night there was no longer any noise heard, and where the columns of fire had been nothing was seen but smoke, whilst smoke only was emitted by the great central crater.

The first signs of a great eruptive paroxysm had spread consternation in people's minds, as it seemed there could be no longer any doubt that a great eruption of Etna was about to take place, and that it would last for a long time, as is usually the case when the outbreak occurs on the side of the mountain. Moreover a great and lasting lateral eruption, when it occurs at a great elevation, almost invariably produces serious damage, burning up woods and fields, and destroying all on the surface over which the lava flows.

However, as I have said, the eruption, after lasting seven hours, began unexpectedly to abate; and so rapidly did this proceed, that in the short space of two days nothing was left of it but some secondary phenomena.

To minds already alarmed there remained, however, a cause of terror even when the flames had ceased, and one which kept them in some uneasiness for a fortnight, namely the frequent earthquakes, which commenced at 11 or 11 on Sunday, August 30, at the same time that the eruption began to abate, and agitated the ground of this neighbourhood, and continued to do so incessantly for the first eight days. Those who at this time. visited the country lying north of Etna received a most dismal impression. All the inhabitants, poor and rich alike, have forsaken their dwellings; the streets and squares and the

neighbouring fields are encumbered with beds and tents, and with huts formed in a thousand ways, in which whole families have taken refuge, and temporary altars as a substitute for the churches now closed to the worshippers. This forced emigration of the inhabitants from their houses is perhaps no longer necessary, as the shocks of earthquake have become less felt and less numerous; and in fact even during the first few days, when they were the strongest, the shocks, being simply undulatory and not upheaving, did little damage beyond some cracks in a few old walls. But experience, by which the people are ruled, has habituated the country folks to dread their burning mountain, which, however, being with its fruitful soil the cause of their wealth, they will not abandon. They rather resign themselves with a sort of indifference to the tribute of sacrifice which Etna sometimes requires of them.

After this preface I will now give an abstract of the observations I made on the scene of the eruption, which contains the exact details of the volcanic disturbance we have witnessed at Mongibello.

On the day in question (August 29), at 4 P.M., when the two powerful shocks of earthquake were felt, starting from the elevated base of the great central crater, at a point on the north side where the crest which surrounds and limits the hollow (known as the elliptical crater) presents a remarkable depression, and descending for a distance of five kilometres to the level of the so-called "Timpa Rossa" and of the Monte Nero, the earth was rent by the violent shock, which, to judge from its effects, must have been of extraordinary force; this produced a long chasm, the axis of which was 8° north of east. The centre of impulsion was on the northern flank of the mountain, 2450 metres above the level of the sea, and exactly between the two hills of lava called the Fratelli Pii (or otherwise I Due Pizzi) and an old crater known by the name of the Monte Grigio. At this point, where the dynamic effect on the earth was the greatest, the chasm was from 51 to 60 metres in breadth; and going further down this was gradually reduced to 30, 20, 15, 10, 5, and 3 metres, till it ended, having altogether a length of about 3 kilometres. From this point upwards, toward the elevated base of the central crater, where the earth had presented greater resistance, the continuation of the upheaval was shown by jets of smoky vapour which appeared in the same direction. That at this height of 2450 metres the greatest volcanic force has been expended is shown by the formation of a new mound, or crater, the upper edge of which has an elliptical form, and which has its major axis in the direction 8° north-east of the chasm. The upper edge of this new crater has a circumference of about

300 metres and a diameter of about 100 metres, and a height of 50 metres from its base: this, with an inclination of the sides of about 30°, gives us a base of 860 metres circumference; and the mound occupies therefore an area of 117,734 square metres. This crater, which looks like a new mountain, is formed of a heap of fragments of doleritic and prehistoric labradoritic lavas of a grey colour, which have been brought up from a great depth by the force of the outbreak of modern lava, which seems in parts to have kneaded the other together. It is singular to see all round this new crater for an area of half a kilometre radius, blocks, lumps, and larger or smaller fragments of this prehistoric lava of a clear grey colour scattered about, contrasting with the present lava, which is very black, and with which they seem here and there to be lined; so that we thus have the lavas of two widely distant epochs brought into contact-one representing an eruption which no man can have witnessed, the other produced by an eruption of today.

The interior of the crater exhibits the usual funnel-shaped form; but its depth has no visible limits. We look across a dark cavernous mouth on whose walls may be seen (as far as the light reaches) jutting out strata of lava of various epochs one above another. The structure and origin of this crater are of great scientific interest.

Moving from this culminating point and following the chasm on which it is placed, we find that for some distance it passes across a stream of lava of uncertain date, but of the past century, for a distance of about half a kilometre.

Here near the base of the crater the chasm presents a maximum breadth of from 50 to 60 metres; and here we see ten small craters of some considerable depth, which, placed one after the other, resemble a row of button-holes. Of these, those nearest to the crater are wide abysses 25 or 30 metres in diameter; the others have a mean diameter of about 10 metres.

After these ten openings, constituting the first group of small craters, and as we continue to follow the chasm as it grows narrower, we find, after a short interval produced by an inequality of the ground, four others near each other, their mean distance from each other being from 2 to 3 metres. Then at a distance of 10 metres further on we find four others in the same proximity to each other as the first four; and these eight together form a distinct group.

Another interval of about 50 metres then occurs, the chasm continuing without any further openings until again four other small craters appear very near each other, three being on the principal chasm. The chasm at this point crosses the side of one of the hills called the Fratelli Pii or the Due Pizzi, which conPhil. Mag. S. 4. Vol. 49. No. 323. Feb. 1875.

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sist of solid lava, and the hill has in consequence been split up in various directions; and here again one of the eruptive openings occurs slightly lateral to the principal chasm. These four last small craters form a third group. The diameter of the opening of the second and third groups varies from 1 to 3 metres.

Following the chasm thus far from the crater (that is, for the length of half a kilometre), we find in this way twenty-two eruptive openings, placed along a line in three groups, existing on a nearly flat surface, the mean elevation of which above the sea is 2440 metres, which is now covered with fragments of old lava and with cinders and scoria from the new lava.

Proceeding from this flat ground, which seems a sort of tableland, towards the north, we meet with a declivity at an angle of 13 to 14 degrees, formed by the great current of solid lava of the year 1614. This is full of numerous and recent cracks, and in some parts is completely broken up by the various earthquakes which have taken place. Still we can trace the continuation of the principal chasm through it, and in this continuation for a distance of about 600 metres there are no openings caused by a more active volcanic force; but at an elevation of 2170 metres we find a fourth group of five small craters from 2 to 3 metres in diameter and of an unknown depth, from which a torrent of lava has escaped which has flowed down to a distance of 150 metres with an average width of 60 metres, and having a thickness of 2 metres. This lava-stream, following the inclination of the ground, has flowed towards a branch of the lava of 1809, which, standing out prominently, has checked it; and it has then spread itself out at the base but without passing beyond it. The chasm, however, crosses it, and continues thence downwards through the aforesaid great current of 1614 for another half kilometre; in this distance appears a fifth group of three small craters at 2150 metres elevation. This is the most active group of all, as it has sent forth a lava-stream about 400 metres in length, 80 in average width, and 2 in thickness; and this forms two short branches deviating towards the west.

Finally, the last portion of the chasm in a length of about 50 metres presents a sixth and last group of five craters very near together, from 1 to 4 metres in diameter, which have emitted a large quantity of cinder and some fragments of scoria. This sixth group of craters marks the lower limit of the chasm visible on the surface of the soil, this point being at 2030 metres above the level of the sea, 12 kilometres distant.

To sum up what has been said, we have :

1st. The most remarkable rent in the ground, extending from the lower edge of the new crater in the form of a principal chasm slightly tortuous in direction, the most important part of which

extends for a length of 3 kilometres, with a width varying from 60 to 3 metres. This is set in the direction N. 8° E., and if extended upwards would join on to the central crater of Etna like a sort of ray, which, prolonged downwards to the extreme circumference of the mountain, would meet the old crater of Majo. Besides this principal chasm there are innumerable cracks which seem collateral and radiating from the centres of strong dynamic action.

2nd. Next to this chasm the principal effect of the eruption is the,new mountain, raised up in a few hours, which constitutes the crater, formed of a regularly shaped heap of blocks and fragments of old labradoritic lavas brought up by the shock from the great depths and partly cemented together by the new lava. Then also there are the six groups of small craters, numbering in all thirty-five, which, following the eruption, constitute a system of elevated crater-shaped mounds.

3rd. The lava, which, besides that forming the crater, and that which is spread over a vast belt in the form of cinders, scoria, and sand, also constitutes two torrents, one 150 metres long, the other 400 metres.

According to the above measurements of these torrents and of the crater, we find that the following quantity of lava was produced by the eruption :

By the first torrent, in cubic metres

By the second torrent,

By the crater

18,000

64,000

Total mass brought to the surface, in cub. met. 1,351,000

All this mass occupied a surface of:

For the first torrent of lava, in square metres.

32,000

Second torrent,

Crater

Total, in square metres.

That is, equal in extent to 24 hectares, yet without doing any damage, the soil here being entirely formed of bare rocks.

If, however, the lava had been able to continue its course, it would soon have come into contact with a wood lying between Randazzo and Lingua Glossa.

4th. The old lavas, irrupted from strata deep in the earth, consist of a pale-coloured dolerite, and grey and compact augitic labradorite, identical with that which forms part of the backbone of Etna and crops up in the exposed strata or in the banks of the Valle del Bove. The new lava, on the contrary, is more or less full of scoria, of an augitic character and of a black colour, like all modern lavas; and it often has a metallic lustre. It is also mag