356 G. P. Scrope on Craters, and the Liquidity of Lavas. 
aériform explosions take place from openings upon lateral fissures, 
and produce those minor, or (as they are often called) parasitic 
cones, of which several examples occur on tha flanks both of 
Vesuvius and Etna. At other times, the explosions are confined 
to the central vent of the volcano, the lava alone welling out, 
perhaps, at some lateral orifice. This, indeed, is the normal 
character of these phenomena. And it is this habitual predi- 
mn (as it <a be —_ of volcanic eruptions for the same 
cone with its crater, rising within the circumference of some 
— crater of earlier date, or in its immediate vicinity. The 
walls of the latter crater are of course often broken down on 
one or more sides (generally on the line of the original fissure); 
—perhaps reduced to a mere segment of its original circuit, by 
the combined operations of volcanic convulsions and <a 
erosions. wert will take the umnible to examine caref oo 
an accurate map, on a sufficiently large scale, of almost pl vol- 
pare — (och, for wari Talos as Vesuvius and the 
: of Vesuviuswhich ies comes so often before us hecaume 
1756, Vesuvi no le three co d craters, 
one within the other, like a nest of boxes, besides the t ens 
and ne a Somma (fig. LD). ng W. 
gives us a drawing of its appearance in this sta 
By the beginnin of the year 1767, the Sen of snot! 
erate eruptions had obliterated the inmost cone and increased 
the ae one, until it very nearly filled the se 0 
completed the process, and re-formed the single cone into 
ean sy all round ~via downwards 2,0, 
lines in fig. 2 (after Hamilton) represent the 
