176 Account of the Eruption of Vesmnus, 



margin, but somewhat less than three-quarters of a mile in 

 its longest diameter ; which is directed from N.E. to N.W. 

 Its depth is perhaps rather above 700 feet, but decreases daily 

 by the dilapidation of the sides. 



The enormous quantity of matter which, previously to the 

 eruption, occupied this space, was thrown out in fragments of 

 every size, varying from blocks of some tons in weight, to 

 the most impalpable powder. The greater part, however, cer- 

 tainly issued from the mountain in the latter form, having un- 

 dergone a complete trituration during the process of continued 

 and repeated ejection. After the first four days of the eruption, 

 the substances thrown out were solely pulverulent, becoming- 

 finer, lighter, and of a lighter colour every day. These ashes 

 as they are called, (certainly without much propriety, being 

 only pulverized lava,) rose from the crater in dense and prodi- 

 gious clouds, to a height, at one time, of nearly two miles, and 

 were thence borne away on the winds to great distances, the 

 heavier particles falling in showers from the line of clouds 

 thus formed along its whole track. The vast crater, which was 

 emptied by this violent process, presents an aspect very differ- 

 ent from that which is usually assumed by the concavities of 

 volcanic cones. These generally appear in the regular form of 

 an inverted cone, whose sides slope at about the same angle 

 to the horizon as those of the outer cone. This is, indeed, in- 

 variably the case with every cone which is produced by a 

 single volcanic eruption. That of Vesuvius, however, resulting 

 from the accumulated products of, perhaps, many hundred 

 eruptions, must consist of numerous beds of scoriae and frag- 

 mentary lava, alternating with the strata of lava rock, which 

 at intervals have been poured in fiery torrents down its outer 

 slope, and congealing there, have remained like so many mas- 

 sive ribs, to give strength and solidity to the structure. 

 Through this succession of beds, then, has the present crater 

 been forcibly hollowed out by the explosive energy of the 

 volcano. It appears as a tremendous abyss of enormous pro- 

 portions, surrounded by craggy precipices that rise almost ver- 

 tically from the rude heaps of fallen fragmejits which fornj its 



