Note 7 — LETTER II.

It is certain, that, by constant attention to the smoak that issues from the crater, a very good guess may be given as to the degree of fermentation within the Volcano. By this alone I foretold[47] the two last eruptions, and, by another very simple observation, I pointed out, some time before, the very spot from whence the lava has issued. When the cone of Vesuvius was covered with snow, I had remarked a spot on which it would not lie: concluding very naturally that this was the weakest part of the cone, and that the heat from within prevented the snow from lying; it was as natural to imagine that the lava, seeking a vent, would force this passage sooner than another; and so indeed it came to pass.