cently been learned that by
pouring soft plaster of Paris into these openings a mould may be
obtained which gives in a surprisingly perfect manner the original
form of the body. The explanation of this mould is as follows: Along
with the fall of cinders in an eruption there is always a great
descent of rain, arising from the condensation of the steam which
pours forth from the volcano. This water, mingling with the ashes,
forms a pasty mud, which often flows in vast streams, and is
sometimes known as mud lava. This material has the qualities of
cement--that is, it shortly "sets" in a manner comparable to plaster
of Paris or ordinary mortar. During the eruption of 79 this mud
penetrated all the low places in Pompeii, covering the bodies of the
people, who were suffocated by the fumes of the volcanic emanations.
We know that these people were not drowned by the inundation; their
attitudes show that they were dead before the flowing matter
penetrated to where they lay.

It happened that Pompeii lay beyond the influence of the subsequent
great eruptions of Vesuvius, so that it afterward received only slight
ash showers. Herculaneum, on the other hand, has century by century
been more and more deeply buried until at the present time it is
covered by many sheets of lava. This is particularly to be regretted,
for the reason that, while Pompeii was a seaport town of no great
wealth or culture, Herculaneum was the residence place of the gentry,
people who possessed libraries, the records of which can be in many
cases deciphered, and from which we might hope to obtain some of the
lost treasures of antiquity. The papyrus rolls on which the books of
that day were written, though charred by heat and time, are still
interpretable.

After the great explosion of 79, Vesuvius sank again into repose. It
was not until 1056 that vigorous eruptions again began. From time to
time slight explosions occurred, none of which yielded lava flows; it
was not until the date last mentioned that this accompaniment of the
eruption began to appear. In 1636, after a repose of nearly a century
and a half, there came a very great outbreak, which desolated a wide
extent of country on the northwestern side of the cone. At this stage
in the history of the crater the volcanic flow began to attain the
sea. Washing over the edge of the old original crater of Monte Somma,
and thus lowering its elevation, these streams devastated, during the
eruption just menti