cut and jointed, even without any cement at all, that they have stood firm for a thousand years.

Upon foundations so infirm, and with materials so frail, buildings are raised to the height of four or five stories. He next remarks on the disproportion of the thickness of the walls to the weights they sustain. Though diminishing exceedingly in thickness from bottom to top, they are still very much weakened by the great number of windows, are overburdened by immense cornices, and little chambers, and kitchens, projecting fearfully beyond the sides; and by terraces and balconies, loaded with enormous vases of stone. The beams which support the floors, scarcely touch upon the walls, are not charred nor faced with lead, to defend them against the moisture, and are almost always injured by the lime in which they lie. Many particulars of this kind, our author has mentioned, all tending to shew the great want of prudence in the manner of building.

In the night of the first of September, 1726, continues Professor Farrana, an earthquake destroyed, or very much injured, all the buildings situated on the muddy soil; and many, which were out of repair or badly constructed, placed on rock. Earth of the nature of the first, is less capable of receiving motion from a shock than the last, since it possesses less resistance. But facts shew that this advantage is more than compensated by want of stability in edifices raised upon it. At Messina, in 1783, all the buildings upon a plain, and upon earth thrown up by the sea, were destroyed; while those on the neighbouring hills were not moved. The same happened at Calabria, and in 1805, in the district of Molise. In this account we should notice the cavities made in the earth. They were esteemed by the ancients as preservatives against earthquakes, not by affording an outlet to the subterranean vapours, as some have thought; but by interrupting or diminishing the course of the shock.

The houses were rebuilt in the same situation, and after the same mode; the fissures of those which were damaged, were as we now observe them, only covered over on the outside by a slight coating of lime. These very places, and precisely the same houses, were this year laid waste; and so they will always be in future, unless a more prudent and more reasonable method shall regulate new buildings and new repairs.

Professor Ferrara proceeds to give a very particular account. of effects of the shock upon buildings in different situations,

which it would be hardly interesting to repeat here. Most of the injury, he says, was done by the second impulse of the shock, when the spear of the vane on the new gate was bent, and the water in the basin in the Botanical Garden was forced violently up one side. Immediately after the shock, he remarks, the apparent injuries were not very great; but the blow was given; and the long and abundant showers of rain which succeeded continued to develope, and increase the injuries, and now, though not very many buildings are entirely destroyed, yet there is scarcely one which has not received some damage. Here follow some notices of the dreadful consequences which befel many of the inhabitants, from the falling of the timbers and stones and walls; of the vases from the piazzas into the streets and many other things which it is unnecessary to mention more particularly. Nineteen persons were killed and twenty-five wounded; in the earthquake of Sept. 1. 1726, four hundred were killed and very many

wounded.

In the close of this chapter he remarks, do not these sad facts impress us with the necessity of every attention in the construction of new edifices? Already have the zeal of the governor, the facilities offered by the senate, and the concern of the active citizens, given a strong impulse to the reparation of the disasters. Soon will the shadow of the past calamity pass away, and the grand city of Palermo will be still more beautiful. When we reflect upon the immense list of earthquakes which Sicily has suffered, and the possibility of its increasing every moment, we feel the inevitable necessity of holding ourselves strongly prepared to meet the sudden assaults of so powerful an enemy. Messina, which suffered so much in 1783, although violently moved by this last shock, experienced from it no bad effects; for this noble city has risen from her ancient ruins, robust and majestic. Catania, in 1818, was convulsed in a terrible manner, but its inhabitants were enabled to contemplate without a tear all the little injury sustained by their beautiful fabrics.*

*After the fatal earthquake of 1693, in Catania, by which eighteen thousand persons perished, the people began to build of one story and always after the plan of barracks. But, as the fear passed from their minds, they raised their houses two stories, and sometimes even three, and not with much solidity. Since the middle of the last century, the excellent materials served them by Etna, the good method and prudent regulation of the stories, have promised long duration to this city. It may possibly be injured, but cannot be easily ruined, although at the foot of the most formidable volcano in the world. After the catastrophe of the 5th of March in Palermo, the VOL. II.-NO. 2.

19

Succeeding Shocks

After the shock of the 5th, the black clouds which covered the heavens on the north and west formed a dark band, measuring from the zenith towards the horizon 60°, and extending from north to south. It was terminated at base by a circular line, passing from north to south, through the west, and ele vated at the southern part about 30° above the horizon. The sky itself was very clear, and its extreme brightness was increased by the contrast with the dark band above, and by the sun just on the point of setting. A little below the band were two other lines parallel and perfectly regular. This mysterious appearance inspired with fear the minds of the people, who are always seeking in the heavens for signs of future events. But it prepared a tempestuous night which followed, with torrents of rain, with thunder, snow, hail, and wind.*

Lieutenant, the Pretor, Senators, and Police exerted all their zeal. They obliged proprietors to prop up their houses within twenty-four hours; or to demolish them if they were not susceptible of proping. The Senate took upon themselves the charge of repairing the houses of poor proprietors, together with the expenses.

* In all times signs have been mentioned as announcing earthquakes near at hand. People read them in the air and upon the earth; and some philos. ophers even, have given them credence. The frequent occurrence of these signs, without the expected phenomena, is a sufficient argument against them. But less uncertain are those which accompany the phenomena, as rain and thunder. To that of 1693 such fearful storms succeeded, that for many hours, at Catania, the groans and voices of the miserable wretches buried under the ruins, were drowned by the roaring of the torrents of rain and the tremendous thunders. The same circumstances took place at Calabria, in 1783; and we were witnesses of the same, on the night of the fifth of March. An extraordinary quantity of electric fluid is developed, and being conducted from the deep cavities of the earth to the surface, by the force of equilibrium, produces there extraordinary vaporization, when hygrometers have shown extreme dryness. The atmosphere, charged beyond measure with vapours, will give room to their decomposition, which changes them into vesicles and then into rain. Fiery meteors will be produced by the electric fluid, liberated by the passage of the vapours to water. If hydrogen gass escape from the earth, it may be inflamed by the electric spark and present the appearance of fires. I should mention here, that in volcanic regions, signs may sometimes precede earthquakes; but this happens there by the proximity of the place of the subterranean operations to the surface of the earth, which circumstance connects the internal phenomena with those of the adjacent atmosphere. On the morning of the 8th of March, 1669, at Pidara, a town on the side of Etna, the air became obscure as by a partial eclipse of the sun; soon after the earth began to shake, and continued so until the 11th, when an immense fissure opened near Nicolosi, a neighbouring town, a sparkling light appeared over the fissure; and on that very day, while the terrible shocks were levelling Nicolosi with the ground, an enormous burning river, amidst horrid rumblings, roarings, and explosions, was belched out, which flowed fifteen miles, covering a great extent of land, and for four months spreading terror over Sicily. Bor. de. inc. in. Ferr. Descr.

dell'Etna.

On the night of the 6th, at forty-five minutes past one, in St Lucia de Millazzo, six miles from the shore which looks towards Volcano and Stromboli, a severe shock was felt, and afterwards, at various intervals, horrible noises were heard, four distinct times, rumbling fearfully beneath them; and finally, at half past three o'clock, the shock was repeated. Both were felt at Messina, but without any subterranean noises. Nothing of it was felt at Palermo, or in any places in the west. At fifty-six minutes past ten, in the night of the 7th, another shock was felt at Palermo, sufficiently strong to put in motion the pendulum of a small clock, which I had stopped that I might regulate it in the morning. Its vibration from N. E. to S. W. showed me with certainty the direction of the shock. Light ones were felt on the 26th. On the 31st, at two and fifty-two minutes, P. M. one was felt at Messina, moderately severe, of five or six seconds duration, and undulating. Two others on the first of April, and one at Costelbuono on the 28th. I should add that they mention a slight one there on the 16th of February, but they are more certain of those of the 5th of March, one at 1. p. m. the other at three. These were they, which induced the inhabitants of Naso to leave their habitations and flee into the country, where they were when their city was laid waste. Here the professor mentions many other places, in which small shocks were felt, in July and August; but as no important remarks are made, we pass over them to his more interesting chapter of physical observations.

Physical Observations.

When the people about Etna perceived their houses beginning to shake, they turned their eyes towards the volcano, and waited in expectation of an immediate eruption. And while they looked, fearful apprehensions filled their minds, and they prayed that the event, be it what it would, might take place at once.

The philosopher, who observes the phenomena of nature, for the sake of reducing to the same class those of an analogous origin, and thence to deduce them from the same cause, observes the link which connects earthquakes with volcanic operations, and sees with the ignorant vulgar, those mighty forces preparing in the subterranean furnace which are able to put in motion immense masses of the solid globe and to agitate them as water is agitated by a violent wind. The

eruption of Etna in 1811 was interesting from the grandeur of the spectacle which it presented, and no less so, from the instruction which it conveyed to the naturalist. A new opening was made on the surface of the mountain. Explosions of tremendous force preceded the emission of immense columns of smoke and inflamed masses of matter, which were incessantly belched out towards heaven, and whose approach was announced by horrid roarings and explosions which filled the air to a great distance. Each explosion was accompanied by shocks; and as the interval between them was of but a few minutes duration, the city and country to a vast extent were in a continued undulation. For many days at Catania, eighteen miles distant, we were rocked as though we had been upon the sea. Some of the shocks were very violent. The door of my chamber which I left purposely ajar, kept a continued beating against its side posts. The shocks lasted as long as the volcano was in operation, i. e. for more than nine months; and when the external phenomena disappeared, the internal fire not being yet extinguished, deep subterranean rumblings and explosions were heard, and shocks felt at each report.

When the fire invests substances, it rarefies their masses to a great degree; the acquisition of new volume produces a proportionate expansion; and under the action of an enormous accumulation of inflamed matter, a passage is made for it with sudden and fearful energy. The expansion of water, for example, under a medium pressure of the atmosphere, is 1728 times its first volume, and it increases in the ratio of the heat. At 110° of Rea. the pressure is equal to four atmospheres only. The explosion of a single barrel of powder, shocks and overthrows the whole vicinity. If, then, a subterranean stream of water happens upon places where volcanic fires are burning, it is at once converted into steam, acquires a density proportioned to the resistance of the mass of earth above it, circulates about, and agitates the most solid mountains and great tracts of land, until losing its heat in the cavities of the earth, it returns to the state of water, without having given any external marks of its existence. It seems that the return of the terrible phenomenon is owing to the flow of water into places on fire-of water, the streams of which are determined only by accidental causes.

The vast furnace in the interior of the earth being inflamed, the fire attacks every thing exposed to its influence, some are liquified, while others are converted to vapour; these, developing their volumes, form a system of force moving with