remarkable cone, which it had become customary in Naples to regard as the true summit of the mountain, fell in, with a dreadful noise, in the last eruption, on the night of the 22d of October (1822): so that the floor of the crater, which had been constantly accessible since 1811, is now 750 (almost 800 English) feet lower than the northern, and 200 (213 English) feet lower than the southern edge of the volcano. Variations in the form and relative position of the cones of eruption,—the openings of which ought not to be confounded, as they often are, with the crater of the volcano itself,—give to Vesuvius at different epochs a different appearance, which would enable a person well acquainted with the history of the volcano, on a mere inspection of Hackert's paintings in the palace of Portici, to tell from the outlines of the summit, according as the northern or the southern side of the mountain is represented as the highest, in what year the artist had taken the sketch from which the picture was made.
In the last eruption, in the night of the 23d to the 24th of October, twenty-four hours after the falling in of the great cone of scoriæ which has been mentioned, and when the small but numerous currents of lava had already flowed off, the fiery eruption of ashes and rapilli commenced: it continued without intermission for twelve days, but was greatest in the first four days. During this period the detonations in the interior of the volcano were so violent that the mere concussion of the air, (for no earthquake movement was perceived), rent the ceilings of the rooms in the palace of Portici. In the neighbouring villages of
