Vokmwes in tJ^e different regions of the Earth, J8S5 



Although the results of which I speak, and which are in per- 

 fect accordance with the accurate observations of Monticelli, 

 differ much from those published some months ago, the eruption 

 of ashes from Vesuvius which took place on the 24th and 28th of 

 October 1822, is undoubtedly the most remarkable of which we 

 have any authentic accounts since the death of the eider Pliny 

 in the year 70. The quantity of ashes which then fell was per- 

 haps three times as great as any that has been observed since 

 volcanic phenomena first began to be studied with attention. 

 A layer of fifty or eighty inches appears at first sight insignifi- 

 cant in comparison of the mass which covered Pompeii ; but, 

 without speaking of torrents of rain, and of the effects of detri- 

 tion, which, in the course of ages, may have accumulated this 

 mass, and without reviving the keen discussion which arose be- 

 yond the Alps, and which was conducted with a great degree 

 of scepticism, respecting the causes of the destruction of the cities 

 of Campania, it is perhaps to the purpose to mention here, that 

 the eruptions of a volcano at periods very remote from each 

 other, can by no means be compared together with reference to 

 their intensity. All the consequences founded upon analogies 

 are insufficient, when the objects to be compared are such as the 

 mass of lava and cindei-s, the height of the columns of smoke, 

 and the loudness of the detonations. 



The geographical description of Vesuvius by Strabo, and 

 Vitruvius's opinion respecting the volcanic origin of pumice, 

 shew, that, until the year of Vespasian's death, that is to say, 

 until the eruption which overwhelmed Pompeii, that mountain 

 resembled more an extinct volcano than a solfaterra. After a 

 long repose, the subterranean forces opened up new paths, and 

 penetrated through the strata of primitive rocks and trachyte. 

 Then must have been manifested effects of which those tliat 

 have since followed could furnish no idea. The celebrated let- 

 ter, in which the younger Pliny relates to Tacitus the death of 

 his uncle, clearly shews that the renewal of the eruptions, and it 

 might even be said the awakening of the doi*mant volcano, com- 

 menced with an explosion of ashes. The same thing was ob- 

 served at Jorullo, when, in September 1759, the new volcano, 

 piercing thraugh the strata of syenite and trachyte, rose sudden- 

 ly in the plain. The country people fled, because they found 



