The corals thus rise to near the surface, but immediately on their being uncovered by the water they die, and the reef ceases to grow. Then the waves by their action break the upper part of it into pieces, which thus become heaped up by degrees on the remainder, until the mass attain so great a height that the sea can no longer wash over it. Thus the curious ring of land is gradually formed, and affords a nutritive soil, in which cocoa-nuts, on being cast ashore, germinate and grow to be large trees. Other seeds, wafted by the waves or carried by birds, also begin to grow, until the whole surface becomes covered with vegetation. Then comes man and builds his habitation upon those fertile spots, and finds in them an agreeable and convenient abode, well suited to those who are accustomed to live by fishing and other simple means. You will thus perceive that the connexion between the atoll and the volcano consists in this--that while the coral builds up the reef, the volcano beneath ingulfs the island and causes it to sink down. In some instances, however, the volcano, after a while, reverses its action, and raises up the island with the reef upon it. In such cases, the coral reefs are seen standing out of the water, forming perpendicular cliffs several hundred feet in height. Then also the interior of the island becomes once more dry land, and that, too, of great fertility. [Illustration: Mount Erebus.] Almost due south of that region, in the Pacific, where the coral islands abound, but at a great distance from them, and considerably within the limits of the Antarctic zone, lies South Victoria. Here, in lat. 76 degrees S., Captain Ross discovered, in 1841, two volcanoes, which he called Erebus and Terror, after the names of his two ships. Of the former, which is the higher of the two, a view is given in the annexed woodcut. It is covered with perpetual snow from the bottom even to the tip of the summit. Nevertheless, it is continually sending forth vast columns of vapour, which glow with the reflection of the white hot lava beneath. These vapours ascend to a great height, more than two thousand feet above the top of the cone, which is itself twelve thousand feet above the level of the sea.