VESUVIUS, ve'-sievi-iis, Italy, a volcanic mountain, 10 miles southeast of Naples. With a basal circumference of about 30 miles, it rises from the centre of a plain 2,300 feet above the sea in a pyramidal truncated cone 1,500 feet high and about 2,000 feet in diameter; total height, 3,800 feet In 1880 a funicular railway was laid to the summit, which was reconstructed and equipped for electrical working 1903-04, and supplemented by a new electric railway four and three-quarter miles long, from Pugliano, the northern quarter of Resina, thus enabling vis itors to travel by electricity from Naples to within 250 yards of the crater. Previous 'to an eruption about 1838, the top was an uneven plane, but was then convened into a hollow cup, with a rim 400 feet to 500 feet broad on its west side, and not more than 50 feet 011 the others, and with an internal sloping sur face to a depth of 500 feet. A precipitous rocky ridge, forming an arc of a circle, and 1,400 feet in height, called the Monte Somma, is situated at a short distance from the cone on the north, from which it is separated by a deep valley called the Atrio del Cavallo. Near the western extremity of this valley is the observatory es tablished expressly for watching the volcanic phenonmena. The lower part of the sloping plain, which rises gradually from the sea to the foot of the cone, forms a belt about two miles broad along the shore, laid out in vine yards and well cultivated, though intersected at intervals by- terraces of black calcined mat ter. Beyond the cultivated belt the plain is rugged and covered with scorix of all forms and sizes. The cone itself is covered with loose matter composed of scorix, blocks of lava and volcanic sand, arranged in successive layers by the natural force of gravitation. The form of the pyramid has been modified by side erup tions and by the internal force acting upon an external matter before it has cooled An in ternal movement of elevation has been proved by the angle at which continuous streams of lava are now found, being much greater than that at which they are known to have origin ally flowed. A stream of lava ceases to be
continuous, and breaks into masses of scorix at an angle of more than 3°. Monte Somma is supposed to have formed at one time a com plete cone of much larger dimensions and probably of greater height than the present cone, being subsequently thrown down by volcanic forces, in the same manner as 800 feet of the present cone was carried away by an eruption of 1822. From a difference of structure imply ing greater pressure, geologists have concluded that Somma was a submarine volcano, while the present is a subacrial one. Till 63 A.D., when many of the surrounding cities were damaged by an earthquake, no symptoms of activity are known to have been given forth by Vesuvius In 79 occurred the great eruption described in the well-known letters by the younger Pliny, which buried Herculaneum and Pompeii, and during which the elder Pliny perished while hastening with part of the Roman fleet to the relief of the inhabitants. Since that time there have been continuous symptoms of activity and numerous eruptions have taken place. . The first recorded discharge of liquid lava after that of 79 was in 1036. Since then there have been many violent eruptions; tbe most noted were those of 1779, 1793, 1834, 1847, 1850, 1855, 1867, 1872, 18'78, 188.0 and 1895. The eruption of 1779 was particularly magnificant flames of fire ris ing to three times the height of the mountain, and stones, scorim, etc., being projected as high as 2,000 feet, while a river of lava 1,500 feet wide flowed for three and a half miles and ex tended 600 feet into the sea. In 1872 14 dif ferent orifices opened in the mountain sending forth rivers of lava that threatened to carry devastation far and wide. The villages of San Sebastiano and Massa di Somma were almost entirely destroyed. Early in April 1906 erup tions destroyed several small towns and vil lages in the vicinity and created wide devasta tion throughout the surrounding territory. See HERCULANEUM ; POMPEII ; VOLCANO.