The summit of a volcano generally terminates in a central cavity or crater, where the eruptive channel finds its vent. Craters are sometimes regularly funnel-shaped, descending with slanting sides to the eruptive mouth, but more commonly they are surrounded with high precipitous rock- walls, while their bottom forms a plain, which is frequently completely horizontal, and sometimes of a considerable extent. Its surface is rough and uneven, from the mounds of volcanic sand, of scoriæ, or of hardened lava with which it is covered, and generally exhibits a scene of dreadful desolation, rendered still more impressive by the steam and smoke, which, as long as the volcano continues in an active state, issue from its crevices. Within this plain, the eruptive orifice or mouth of the volcano is almost universally surrounded by an elevation, composed of ejected fragments of scoriæ thrown from the vent. Such cones are forming constantly at Vesuvius, one being no sooner destroyed by any great eruption, before another begins to take shape and is enlarged, till often it reaches a height of several hundred feet. Thus the crater of an active volcano is the scene of perpetual change—of a continual construction and re-construction, and the sands of the sea do not afford a more striking image of inconstancy. The various craters are of very different dimensions. While the chief crater of Stromboli has a diameter of only fifty feet, that of Gunong Tenger, in Java, measures four miles from end to end; and, though the depth of a crater rarely exceeds 1,000 or 1,500 feet, the spectator, standing on the brink of the great crater of Popocatepetl, looks down into a gulf of 8,000 feet. From the colossal dimensions of the larger craters, it may well be imagined that their aspect exhibits some of the sublimest though most gloomy scenery in nature—the picture of old Chaos with all its horrors. The volcano Gunong Tjerimai, in Java, which rises to the height of 9,000 feet, is covered with a dense vegetation up to the crater’s brink. On emerging from the thicket, the wanderer suddenly stands on the verge of an immense excavation encircled with naked rocks. He is obliged to hold himself by the branches of trees, or to stretch himself flat upon the ground, so as to be able to look down into the yawning gulf. The deep and inaccessible bottom of the crater loses itself in misty obscurity, and glimmers indistinctly through the vapours which are there slowly and incessantly ascending from its mysterious depths. All is desolate and silent, save when a solitary falcon, hovering over the vast chasm, awakes with her discordant screech the echoes of the precipice. Through a telescope may be seen, in various parts of the huge crater walls, swarms of small swallows, which have there built their nests, flying backwards and forwards. The eye can detect no other signs of life, the ear distinguish no other sound.