Eruption of Mount Fesuvius in 1828. 303 



of perfect calm ; but the examination of the crater was still 

 interesting. The whole of the interior appeared as if lined 

 with black velvet, in consequence of the great quantity of sand 

 which fell on the 26th. The bottom of it, by the frequent 

 rising of the substance which formed it, and by a mass of 

 scoriaceous lava which accumulated on its surface, was raised 

 above its former level about forty toises, or perhaps still more, 

 adjoining the sides. It appeared like the scum which, lines a 

 vessel when filled with a liquid in a state of fermentation. 



On the north-east the lava had already formed an oblique 

 eminence, supported against the interior surface of the crater, 

 where there still remained vertical fissures, animated with 

 living fire, and exhaling much vaporous smoke. This eruption 

 was exceedingly beautiful and interesting ; for every volcanic 

 or igneous phenomenon which took place was observable, 

 without danger, within the vast area of the existing crater. 

 The shortness of the volcanic crisis can be attributed only to 

 two causes; firstly, because the volcanic funnel was very 

 superficial, and very little resistance was opposed to the 

 igneous power, which, being exhausted, could scarcely furnish 

 from itself more combustible materials, because deficient in 

 them ; secondly, because subterraneous currents of air pre- 

 vented the fire from receiving the inflammable materials from, 

 strata beneath. This opinion may be thought a bold suppo- 

 sition ; but in observing the mode of action of the volcanic 

 mouths, the same appearance was visible as when a fire is 

 blown with a pair of bellows. This idea has occurred to me 

 from what I have many times noticed, and which may be 

 verified at the present time, that in some fissures in the western 

 part, the air enters with a loud whistling sound, but perfectly 

 kalophonious. During the short time of the eruption, the 

 water did not decrease in any of the wells in the neighbour- 

 hood of Vesuvius. 



The pumiceous scoriae, which fell on the 21st on the 

 southern part of the summit of the cone, were of a greenish 

 colour, and filamentous ; some filaments not thicker than the 

 finest hair, and others an inch in diameter. The result of the 

 mechanical analysis, a method adopted by Professor Cordier, 

 showed them to consist of an intimate mixture of pyroxene 



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