Columbus divided the circumference of the earth at the equator, according to Ptolemy's system, into twenty-four hours of fifteen degrees each, making three hundred and sixty degrees. Of these he imagined that fifteen hours had been known to the ancients, extending from the Fortunate or Canary Islands to the city of Thinoe in Asia, the western and eastern boundaries of the known world. By the discovery of the Cape de Verd and the Azore Islands, the Portuguese had advanced the western frontier one hour, leaving about one eighth of the circumference of the globe yet to be explored. The extent of the eastern region of Asia was yet unknown, although the travels of Polo in the fourteenth century had extended far beyond the Oriental boundary of Ptolemy's map. Columbus imagined that the unexplored part of Asia might occupy a large portion of the yet undefined circumference of the earth, and that its eastern headlands might approach quite near to those of Western Europe and Africa. He therefore concluded that a navigator, pursuing a direct course from east to west, must arrive at the extremity of Asia by a far easier and shorter route than following the coast of Africa around the Cape of Good Hope. Fortunately, he adopted the opinions of Aristotle, Pliny, and other writers, who considered the ocean as but of moderate breadth, so that it might be crossed from Europe in the space of a few days. A knowledge or suspicion of its actual extent would have deterred even the bold enterprise of Columbus from attempting an exploration of its waters in the small ships of that day. Reports of strange trees, reeds of immense size, curiously-carved pieces of wood, and the bodies of two men-unlike, in color and visage, any of the known races extant- having drifted ashore upon the Canary and Azore Islands by westerly winds, confirmed him in his belief, and a desire and determination to undertake a demonstration of his theory by an exploring voyage absorbed his whole attention. "He never spoke in doubt or hesitation," says Irving, "but with as much certainty as if his eyes had beheld the Promised Land. A deep religious sentiment mingled with his thoughts, and gave them at times a tinge of superstition, but of a sublime and lofty kind. He looked upon himself as standing in the hand of Heaven, chosen from among men for the accomplishment of its high purpose. He read, as he supposed, his contemplated discovery foretold in Holy Writ, and shadowed forth darkly in the prophecies. The ends of the earth were to be brought together, and all nations, and tongues, and languages united under the banner of the Redeemer." * The prophetic passage in Pulci's "Morgante Maggiore" was to him full of promise: "Know that this theory is false; his bark The daring mariner shall urge far o'er The Western wave, a smooth and level plain, Albeit the earth is fashion'd like a wheel. Man was in ancient days of grosser mold, And Hercules might blush to learn how far