Eruption of Mount Vesuvius in 1828, 305 



began in a little time to form a cone, which, on the 4th, had 

 risen to the height of nearly one hundred feet, truncated hori- 

 zontally at the summit, where it appeared about eighteen feet 

 in diameter. This cone became the base of two semicircular, 

 ignivomous apertures, one sloping towards the north, the other 

 vertical. They occupied a considerable part of the trunca- 

 ture, leaving, however, a large part unaltered in appearance. 

 The explosions were renewed about every three minutes ; the two 

 mouths alternating with each other. Part of the scoriae, which 

 fell, rolled down the declivity of the new cone, and part rested 

 on the summit ; so that it increased both in height and dia- 

 meter. Flames, with bluish smoke, continually issued from 

 these mouths, with a whirling motion, and, while rising in the 

 air, preserved (as before) the form of pine trees. All the 

 sides of the great cone appeared to have an undulatory motion. 

 This I verified by placing a pitcher full of water on the highest 

 point of the great cone. The water, at the moment when the 

 subterranean detonations were felt, manifested an undulating 

 motion, and fell from the sides of the pitcher. I repeated the 

 experiment several times, and the same undulation constantly 

 took place ; so that, although the present eruption was nothing 

 in comparison with so many others which had taken place, it 

 appeared conclusive that it was sufficient to impart an undula- 

 tory motion to the whole of the cone. 



The rain which fell at three o'clock on the night of the 5th 

 of July seemed to cause a cessation of the igneous explosions ; 

 but instead of these, cinders were ejected, of a grey or brown 

 colour, which fell on nearly all the hills in the neighbourhood 

 of Vesuvius, and on the plains and gardens of the Torre dell 1 

 Annunciata. The husbandmen were not sorry to find their 

 lands covered with this heated sand, for experience had taught 

 them its utility in the culture of cotton and rice. 



On that morning Vesuvius appeared most interesting, and 

 particularly at the rising of the sun, which was immediately 

 preceded by a rainbow a magnificent spectacle, and which I 

 have never before known to have been observed. 



To attempt an explanation of this very short eruption would 

 be to immerse oneself in a sea of conjectures, without deriving 



