There are groups of islands scattered over the tropical ocean, especially, to which might well be given Herman Melville's name, "Las Encantadas," the Enchanted Islands. These islands, usually volcanic, have no vegetation but cactuses or wiry bushes with strange names; no inhabitants but insects and reptiles--lizards, spiders, snakes,--with vast tortoises which seem of immemorial age, and are coated with seaweed and the slime of the ocean. If there are any birds, it is the strange and heavy penguin, the passing albatross, or the Mother Cary's chicken, which has been called the humming bird of ocean, and here finds a place for its young. By night these birds come for their repose; at earliest dawn they take wing and hover over the sea, leaving the isle deserted. The only busy or beautiful life which always surrounds it is that of a myriad species of fish, of all forms and shapes, and often more gorgeous than any butterflies in gold and scarlet and yellow. Once set foot on such an island and you begin at once to understand the legends of enchantment which ages have collected around such spots. Climb to its heights, you seem at the masthead of some lonely vessel, kept forever at sea. You feel as if no one but yourself had ever landed there; and yet, perhaps, even there, looking straight downward, you see below you in some crevice of the rock a mast or spar of some wrecked vessel, encrusted with all manner of shells and uncouth vegetable growth. No matter how distant the island or how peacefully it seems to lie upon the water, there may be perplexing currents that ever foam and swirl about it --currents which are, at all tides and in the calmest weather, as dangerous as any tempest, and which make compass untrustworthy and helm powerless. It is to be remembered also that an island not only appears and disappears upon the horizon in brighter or darker skies, but it varies its height and shape, doubles itself in mirage, or looks as if broken asunder, divided into two or three. Indeed the buccaneer, Cowley, writing of one such island which he had visited, says: "My fancy led me to call it Cowley's Enchanted Isle, for we having had a sight of it upon several points of the compass, it appeared always in so many different forms; sometimes like a ruined fortification; upon another point like a great city." If much of this is true even now, it was far truer before the days of Columbus, when men were constantly looking westward across the Atlantic, and wondering what was beyond. In those days, when no one knew with certainty whether the ocean they observed was a sea or a vast lake, it was often called "The Sea of Darkness." A friend of the Latin poet, Ovid, describing the first approach to this sea, says that as you sail out upon it the day itself vanishes, and the world soon ends in perpetual darkness:-- "Quo Ferimur? Ruit ipsa Dies, orbemque relictum Ultima perpetuis claudit natura tenebris."