Origin of Mount Etna. S81 



the mountain in the direction of one of its meridians. As soon 

 as sucli a fissure is formed, the lava which bubbles up in the 

 central vent speedily enters, and almost always opens for itself 

 there a passage, by which it flows out laterally on the flanks of 

 the volcano, producing a lateral eruption. Many eruptions of 

 this description have taken place at a great distance from the 

 axis of the mountain, and at an inconsiderable height above the 

 Bea ; one occurred near Catania, at a distance of six leagues 

 from the great crater. 



The lower part of each of these meridional fissures, of which 

 I have been speaking; remains filled with lava, and a vein is 

 thus formed. As to the upper part of the fissure, situated above 

 the point whence the lava flows, it ofien becomes filled with 

 scoriye or debris ; some, however, of these fissures have re- 

 mained empty, and a part of the grottos which are mentioned as 

 occurring in the mass of Etna have had no other origin. Near 

 Nicolosi, there is a grotto called Grotta dei Palombi, whose en- 

 trance was cleared by M. Mario Gemellaro, and into which I 

 descended. The breadth of the internal hollow varies from one 

 to four yards, and I regret I cannot describe it at present. 



In the eruption of 1832, the phenomenon of meridional frac- 

 tures presented itself, accompanied by remarkable circumstances. 

 A fissure was produced in the direction of Bronte, and thus 

 opened an exit for the lava on that side ; another rent com- 

 mencing at the summit, which was till lately the most elevated, 

 and which was at last broken down by this occurrence, crossed 

 the Piano del Logo in the direction of Catania ; other accessory 

 fractures took place at the same time ; and in this eruption, to 

 make use of a common expression, the mass of Etna was com- 

 pletely " etoiUy The rent which traversed the Piano del Logo 

 produced destructive effects, which, if our lime permitted, would 

 be well worthy of being particularly mentioned. But the most 

 curious, perhfjps, of the results produced by this fracture was, 

 that, in dividing the plain termed the Piano del Logo, it changed 

 the relative Jevel of the two segments to an extent amounting 

 often to more than a metre. On the eastern division, which has 

 sunk in height relatively to the other, are still to be seen the 

 ruins of a small ancient edifice called the "Porre del Filoso/b, 

 which was built 1500 or SOOO years ago. During this lapse 



