[ 29 ] 
fore defcribed. It is not therefore likely, that the whole 
of mount Vefuvius fliould have been made at fever al 
times, by the earth and cinders flung up out of the 
mouth, that lies in the midft of them, the afhes falling 
down the fides of it, like the fand in an hour-glafs, as 
Mr. ADD IS ON particularly obferves, and as moft peo- 
ple are naturally enough apt to think. And however 
conflderably the bulk of this mountain may have been, 
increafed, by the loads of lava thrown out at the feveral 
eruptions ; yet no great addition feems to have acceded 
to its height, if the obfervation juft mentioned be true ; 
which, though I have never had it in my power to verify, 
yet I readily believe; not only on account of the relpedta- 
ble authorities above quoted, but alfo from its confiftency* 
with other flmilar andindifputable phaenomena, of which 
the vulcanic branch of Montebello before defcribed af- 
fords, if I miftake not, no inconflderable proof. Nor does 
it indeed appear agreeable to reafon, that mountains of 
great height, where volcanos exift, fliould be entirely vo- 
mited up in this manner; fuch volcanos feeming to re- 
quire a folid and permanent channel for the violence and 
frequency of the effects they produce. It feems there- 
fore, that a Avay or channel only has been opened, by an 
original effort or explofion, through mount Vefuvius, 
which has fince been deeply buried by the materials fuc- 
ceflively thrown up, from its bowels, in the feveral erup- 
tions. And I am inclined to think the fame of mount 
^^itna, from its fuperior height, though I am uncertain 
(h) Travel?, p. 184. 
whether 
