t DESTRUCTION OP HERCULANETJM. 201 
jfeand. We think it maybe admitted, then, as an es- 
tablished fact, that no stream of lava has ever 
reached Pompeii since it was first built, although 
the town was built upon a lava foundation. 
At Herculaneum, Mr. Lyell thinks the case is 
different ; although the substance which fills the in- 
terior of the houses and the vaults must have been 
introduced in the state of mud, yet the superincum- 
bent mass differs both in composition and thick- 
ness. As Herculaneum was situated several miles 
nearer to the volcanoes, it was, of course, more ex- 
posed to be covered, not only by showers of ashes, 
but by alluviums and streams of lava. Accordingly, 
masses of both have accumulated on each other 
above the city, to a depth of nowhere less than 70, 
and in many places of 112 feet. The tuff which 
envelops the buildings consists of pumice mixed 
with comminuted volcanic ashes. 
Herculaneum was discovered in 1713 by the ac- 
cidental circumstance of sinking a well, which came 
right down upon the theatre, where the statues of 
Hercules and Cleopatra were found. No buildings 
but this are open to inspection, as the Porum, Tem- 
ple of Jupiter, and other buildings have been fill- 
ed up with rubbish as the workmen proceeded, ow- 
ing to the difficulty of removing it from so great a 
depth below ground. " Both at Herculaneum and 
Pompeii," says Lyell, " temples have been found 
with inscriptions commemorating the rebuilding of 
the edifices after they had been thrown down by 
an earthquake, which happened in the reign of 
Nero, sixteen years before the cities were over- 
whelmed. In Pompeii, one fourth of which is now 
laid open to the day, both the public and private 
buildings bear testimony to the catastrophe. The 
walls are rent, and in many places traversed by 
fissures still open. Columns are lying on the 
ground only half hewn from huge blocks of traver- 
tin, and the temple for which they are designed is 
