128 Prof. 0. Silvestri on the Eruption of Etna 



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 emigra- 

 tion 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 moun- 

 tain, which, however, being with its fruitful soil the cause of 

 their wealth, they will not abandon. They rather resign them- 

 selves 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 observa- 

 tions 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 ele- 

 vated 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 



