In the last chapter we described the manner in which a certain class of islands in the South Seas are formed; in the present we will make a few observations on another class, which have sprung up from the bottom of the sea, as if by magic, under the irresistible influence of fire. There are volcanoes in the sea, as well as on the land; and these volcanoes have in former times up-heaved huge masses of land so as to form large islands, while in other cases they have caused islands formerly in existence to subside and disappear. In the writings of the ancients we find reference made to an island which, if it ever did exist, now exists no longer. It was situated opposite the Straits of Gibraltar, was nearly two hundred miles in length, and was called "Atlantis"--hence the name of the Atlantic Ocean. Many believe, and with some reason, we think, that this island was not altogether a myth, although much that is said of it is undoubtedly fabulous. Plato tells us that it was a large island in the Western Ocean, situated before or opposite to the Straits of Gades; and that out of this island there was an easy passage into some others which lay near a large continent, exceeding in bigness all Europe and Asia. So far Plato may have told the truth, and from this passage it is conjectured that the existence of the continent of America was known to the ancients. But he goes on, immediately after, to draw upon his imagination, and to tell us that Neptune settled on this island, and that his posterity dwelt there for a period of nine thousand years in the midst of fertility and abundance. But, not content with their ample possessions and prolific soil, they went over to Africa and Europe, and even penetrated into Asia, bent on conquest. Passing from this mixture of probable truth and undoubted fable, Plato then asserts that the island of Atlantis finally sank and disappeared. This may or may not be true, but there is more reason for our crediting the statement than many people would suppose. Certain it is that no such island exists at the present time, but it is believed by some that the Azores, which are volcanic in their formation, are the summits of the mountain ranges of the Atlantis of the ancients. But the best evidence we have of the possible existence of such an island is the fact that in modern times an island has been _seen_ to rise out of the sea, and, after a time, to disappear, under the influence of volcanic action. This remarkable event is related by Captain Tillard, an officer of the British Navy, who saw it on the 12th of June 1811, when approaching the island of St. Michael. On this occasion smoke was seen to rise from the surface of the sea, and, soon after, showers of cinders to burst forth. We cannot do better than give the captain's own words, as follows: