VESUVIUS (Veserus), a mountain situated east of the bay and east-south-east of the city of Naples, celebrated for many centuries as one of the principal and most active volcanoes of Europe. Its height above the sea is variable, according to the condition in which eruptions leave the crater; and owing to the same causes the figure of the mountain, though in a general sense always conical, changes from time to time. During the early part of the present century the top of Vesuvius had become a rough and rocky plain, covered with blocks of lava and scorite, and cut by numerons fissures, from which clouds of vapour were evolved. By the violent eruptions of October, 1822, this was all thrown out, and replaced bye vast elliptical gulf or chasm three miles in circumference, three-quarters of a mile in the longest diameter, and perhaps 2000 feet in depth. More than SOO feet of the summit of the ancient cone were carried away by the explosions, and the height of the mountain was thus reduced from 4000 to 3200 feet. One of the greatest eruptions of modern times took place in 1955, when vast floods of lava poured down the mountain for about three weeks, destroying the village and township of Cercolo, covering a great extent of vineyards and sweeping away houses and bridges. For about ten miles the vast lava-stream flowed irresistibly on until it almost reached the sea in the direction of the Ponta 31addaloni. The eruption commenced on the 1st of May. After hurling stones and flames for a week, the old crater broke up altogether, and in the middle of the cone ten new craters were formed, whence lava poured forth like a river on the aide of the Cavallo and as far as the Minatore. Here four other craters were formed, which threw up glowing masses of bitumen pyramidal in form, and resembling gigantic fireworks. About the 20th the lava ceased to flow.
The mountain called Somme, which surrounds for half a circle with a precipitons escarpment the true peak of Vesuvius, is part of the Ancient large crateriform cone described by the Roman historians, the summit and part of the side of this ancient cone being destroyed by the explosion of A.D. 79. No record exists of an actual eruption of Vesuvius prior to the Christian era. Diodoms Siculus notices (iv. 21) that it has "many signs of having been burulng in ancient
times ;" and Strabo infers its igneous origin from the nature of the rocks; but the slopes were richly cultivated and proverbially fertile, though the top was a rough, sterile, slightly concave plain, in which Spartacus was besieged by the Roman army. (Florus, iii. 20.) In st.n. 63 the long-dormant volcano gave the first symptoms of renewed agitation In an earthquake, which occasioned considerable damage to many of the cities in its vicinity, amongst others to Pompeii. In the month of August, A.D. 79, occurred the first and perhaps the greatest of all the recorded eruptions of Mount Vesuviae, described in the letter of Pliny the Younger to Tacitus, which records the death of Pliny the naturalist. The cities of Stabile, Pompeii, and Herculaneum were overwhelmed by showers of cinders and loose fragments, no lava having been ejected on this occasion. Other eruptions succeeded in A.D. 203, 472, 512, 885, 903, and 1036, which last is said to be the first which was attended by an ejection of lava. Eruptions were renewed in 1049, 1139 (or 1139), 1306, 1500, 1631, 1660, 1632, 1694, and 1699, from which time to the present phenomena of this nature have been repeated very frequently, so as seldom to leave any interval of rest exceeding ten years. Sometimes this mountain has flamed twice within a few months.
The eruption of 1737 gave forth lava currents, which passed through Terre del Greco into the pea, the aolul cootents beiug estimated at 33.597,059 cubio feet. In 1794 the lava followed the same course, and amounted to 46,093,766 cubic feet. In the various eruptions of this mountain, currents of melted rock, torrents of heated water, clouds of ashes and scoriae, and great volumes of steam and gases have at differ ent times been observed. The force with which the subterranean azeneies operate during their paroxysmal excitement may be judged of by the height (2000 feet) to which stones have been projected, and the distance to which they have been thrown. Stones of 81bs. in weight fell on Pompeii in the eruption of A.D. 79, while masses of an ounce weight overwhelmed Stabim; and in a later eruption fine ashes were transported by the winds even to Constantinople.