1856.] 



SCROPE CRATERS AND LAVAS. 



337 



appeared in the shape of a vast funnel, accessible to its bottom, 

 which for a few years then remained in a tranquil state. In 1841, 

 however, a small cone began to form within it, and increased so 

 rapidly, that in 1845 it was visible from Naples above the brim of 



Fig. 3. — Crater of Vesuvius after the Eruption of October 1822. 



the crater, which soon after was completely filled. And the cone 

 from that time went on increasing in bulk and height from the effect 

 of minor eruptions, until in 1850 one of a violently explosive cha- 

 racter opened the two deep craters on its summit, of which I have 

 already spoken. The more recent eruption of May last, being con- 

 fined chiefly to a prodigious efflux of lava from the outer side of the 

 cone, unaccompanied by any extraordinary explosive bursts from the 

 summit, has not altered materially the form impressed upon it in 

 1850. 



It is thus seen that within the last 100 years the cone of Vesuvius 

 has been five several times gutted by explosive eruptions of a par- 

 oxysmal character, viz. in 1794, 1822, 1831, 1839, and 1850; and 

 its central craters formed in this manner as often gradually refilled 

 with matter, to be again in due time blown into the air. Meanwhile 

 the old external crater of Somma is itself becoming choked up by 

 the accumulation of all the lava-streams and fragmentary matter 

 that are expelled towards the northern and outer side of the cone. 

 It would be, therefore, in exact accordance with the habit of this 

 volcano (as of volcanic mountains in general), if, after some further 

 period either of quiescence or of moderate activity, the entire cone 

 of Vesuvius should be blown up by a more than ordinarily violent 

 paroxysm, and the crater of Somma itself reformed. 



With this well-authenticated history of the mountain within our 

 knowledge, would it not be wholly unphilosophical to deny (except 

 upon such grounds of impossibihty as have never been adduced) 

 that the larger containing crater in the case of Vesuvius (and the 

 argument applies to other similar volcanic mountains) had the same 

 origin as the smaller contained ones ; and that the external cones were 



