Note 15 — LETTER III.

I have since found in this stratum of erupted matter at Pompeii, stones weighing eight pounds: but many accounts of the great eruption of Vesuvius, particularly that of Antonio Bulifon, mention that a stone like a bomb was thrown from the crater of Vesuvius in 1631; and fell upon the Marquis of Lauro's house at Nola, which it set on fire. As Nola is twelve miles from Vesuvius, this circumstance seems rather extraordinary: however, I have seen stones of an enormous size shot up to a very great height by Mount Vesuvius. In May 1771, having a stop watch in my hand, I observed that one of these stones was eleven seconds falling from its greatest height, into the crater from whence it had been ejected. In 1767, a solid stone, measuring twelve feet in height, and forty-five in circumference, was thrown a quarter of a mile from the crater; the eruption of 1767, though by much the most violent of this century, was, comparatively to those of the year 79 and 1631, very mild.