364 Analysis of' Scientific Books and Memoirs. 



other places, those grand laboratories of nature, from causes which will 

 always elude our investigation, may be so deeply seated, that their pro- 

 ductions never arrive at the surface, and that no other evidences of their 

 existence, no other effects of their action are perceptible, but the shaking 

 of the earth, and the rumblings which the aeriform elastic vapours make 

 in the cavities of the earth. 



Three principal furnaces have their outlets on the three sides of Sicily, 

 and each with a force proportioned to the circumstances which supply it 

 with combustible matter. iEtna on the eastern side, by the immensity 

 of its power, rules the whole island. When in full action, the island 

 trembles to its foundation, and feels the mighty power which has borne 

 rule there from time immemorial. Its roarings are heard from one ex- 

 tremity to the other ; but the parts most agitated are those in its neigh- 

 bourhood, and those between it and Cape Passora, a space of about a hun- 

 dred miles. 



The mountain of Sciacca, on the southern shore towards the west, 

 seems to cover a place where the elements have been in ceaseless operation 

 for ages. From dark caverns, which open in the more elevated parts, tor- 

 rents of water, in the form of heated vapour, with sulphurous gases, are 

 ejected. Having penetrated into the internal recesses, but unable to ex- 

 tinguish the fermentation, the water becomes invested with fire, is con- 

 verted into vapour, and thus exhaled into our atmosphere. The extrica- 

 tion of the steam causes, in the internal caverns, a deep roaring, and often 

 fearful convulsions, felt at a distance. At such times, Sciacca, at the foot 

 of the mountain, experiences the most violent commotions. In 1578, it 

 was reduced to ruins. In 1652, for fifteen days, it suffered the most se- 

 vere and unremitted shocks. For some months, in 1724, the earth was 

 so frequently and violently agitated, that all the inhabitants fled into the 

 country. In September 1726, all the western part of Sicily was shaken 

 with the greatest severity ; and, in Palermo, at that time, many lives were 

 lost, and many edifices destroyed ; in June of 1740, Sciacca felt twenty- 

 two shocks, with injury to buildings, and loss of lives ; that of the 25th 

 was of such immense force, that it extended as far as Palermo. After 

 the middle of December 1816, the inhabitants heard extraordinary rum- 

 blings under the mountain, and in January of the succeeding year, the 

 shocks were so frequent, that twelve were sometimes counted in one day, 

 and so violent, that it seemed that the foundations of buildings must be 

 rooted up — the rumblings and explosions under the mountain became 

 fearfully loud — and the sea dashed in great waves against the shore at its 

 foot- Sambuca, fifteen miles distant, suffered much injury. A strong 

 odour of sulphur pervaded the air all about Sciacca. While nature was 

 in this agitation in the western part of the island, the eastern was enjoying 

 perfect quiet. Over against Sciacca, at the distance of seventy miles, 

 Pentellaria rises from the sea, and presents the same phenomena : an island 

 of lava, and other burnt matter, and streams of heated vapour of water, 

 and of sulphur issuing incessantly from its cavities, show a great fermen- 

 tation in the deep caverns under the sea, and to which little is wanting 



