*66 Sir William Hamilton’s Defcription 
the lava, not being abundant, flopped and cooled before it was 
able to reach the valley. By the accumulation of thefe lava’s 
on the flanks of Vefuvius, its form has been greatly altered ; 
and by the frequent exploflon of fcoriae and aflies, a confi- 
derable mountain has been formed within the crater, which 
now riling much above its rim has likewife given that part of 
the mountain a new appearance. Juft before I left Naples, in 
May 1 783, I was at the top of Vefuvius. The crater was cer- 
tainly then more than 250 feet deep, and was impra£ticable, its 
Aides being nearly perpendicular. This eruption, however, 
has been as fatisfadlory as could be defired by the inhabitants 
of this city, a prodigious quantity of lava having been dif- 
gorged; which matter, confined within the bowels of the 
^arth, would probably have occafioned tremors ; and even flight 
ones might prove f^tal to Naples, whofe houfes are, in gene- 
ral, very high, ill built, and a great number in almoft every 
ftreet already fupported by props, having either fuffered by 
former earthquakes, or from the loofe volcanic foil’s having 
been wafhed from under their foundations by the torrents of 
rain water from the high grounds which furround Naples, and 
on which a great part of the town itfelf is built. 
From the time of the laft formidable eruption of Mount 
Vefuvius, in Auguft 1779 (defcribed in one of my former 
communications to the Royal Society) to this day, I have, 
with the affiftance of the Father Antonio Piaggi *, kept an 
exaft diary of the operations of Vefuvius, with drawings, 
ftiewing, by the quantity of fmoke, the degrees of fermenta- 
* This Padre Antonio Piaggi is the ingenious Monk who invented the method 
of unfolding and recovering the burnt ancient manufcripts of Herculaneum, and 
who refides conflantly at Refina, at the foot, and in full view, of Mount 
Vefuvius* 
