They are openings in the surface of the earth, from whence ignited matter of various kinds, smoke, and ashes, are sent forth by some subterranean agency. For the most part they do not always keep in activity, but have long intervals of rest for months, and sometimes for very many years, between the eruptions. One of the few that always keeps in eruption, is Stromboli, one of the Lipari Islands off the coast of Sicily, which there is good reason to think, has been active for nearly 1600 years. This Volcano is merely a mountain or rock, standing out of the sea, and the melted matter, that occasionally runs down its sides, flows directly into the water, and at once kills and parboils the fish that happen to be near it, and they are thus sometimes taken and eaten by the poor fishermen who live about the base of the mountain. The way in which an eruption takes place in a Volcano of the other kind, when it has been quiet for a long time, is as follows. Great noises are heard about the foot of the mountain, and earthquakes frequently occur for several days before any change is seen in the opening or _crater_, as it is called. The springs in the neighbourhood often disappear, and as you may suppose all these forebodings make the people who live near gloomy enough. After a time a dreadful burst takes place, and the crater is in an instant cleared of the stones and earth that may have fallen into it during the period of repose; ashes and cinders, rocks and stones, are thrown up to an immense height in the air, and a great cloud of smoke and steam accompanies them. In perfectly still weather, this vapour is seen to shape itself in a very beautiful manner. The immense impulse from beneath sends it up to a vast height as straight and almost as distinct as a pillar. At a certain elevation, it spreads abroad and assumes the appearance represented in the plate. When this occurs on Vesuvius, the Italians call it the _pine tree cloud_, from the resemblance its form bears to that of a pine tree. As the eruption goes on the cloud of smoke which is always copiously charged with electricity, sends out brilliant lightnings; its form becomes disturbed, and the dark volumes of vapour are angrily sent forth in shapeless masses. Red-hot stones are sent into the air to a stupendous height; the melted matter boils up inside the crater and rolls down the sides of the mountain, setting fire to the trees that it meets with, and destroying or enveloping whatever else remains in its way. You will see their effect as they appear by night, in the other plate. I should tell you that the Volcano represented in both the pictures is Mount Vesuvius. [Illustration: PLATE V. VESUVIUS N^o. 1]