376 CALORIFICATION. 



tains, and looked into their craters in circum- 

 ference about half a mile. Although the inte* 

 rior perpendicular height of many of them did 

 not exceed 200 feet, the depth of their inverted 

 cone within was at least 600, giving out sul- 

 phuric vapours ; and in all there were deposi- 

 tions of salt and sulphur. The ashes were 

 carried as far as Tarento, a distance of 25Q 

 miles, and as far as Lucca, which is still fur- 

 ther ; and the Bishop of J)erry, in a letter 

 from Sienna in the Tuscan state, about 18 hours 

 after the commencement of the eruption, said, 

 that in the midst of a most violent thunder 

 gtorm, about a dozen stones of various weights 

 and sizes, fell at the feet of different persons ; the 

 stones of a quality, not found in any part of the 

 Siennese territory, one of which weighed 5lb. * 

 The torrents of water mixed with ashes and 

 mud that rushed from the summit of Vesuvius 

 to the adjacent countries carried with them 



* It has become a question whether these stones have been 

 generated in this ignious mass of clouds, which produced such 

 universal thunder, or whether they were thrown from Vesu- 

 vius. Is it not probable, that the different meteorological 

 stones which have fallen at different times, have arisen from 

 the same sources? and not from the disruption of mountains 

 in the moon, as the celebrated da Place, and others, have fan- 

 cied. It is, however, a curious circumstance, that these stones 

 are all combined of the same materials ; they are composed of 

 iron and of nickle, with a certain proportion of silex arid of 

 magnesia, a small portion of chrone and iron pyrites. 



