Geographical knowledge grew very slowly. By the beginning of the eighteenth century, explorers had become familiar with the range of the ocean, the outline of the continents, and with many islands. At the beginning of the nineteenth century, four fifths of the land area of the entire globe was unknown. Africa, except a narrow rim of coast, was almost as little known as the planet Mars is to-day. At the opening of the last century men knew little more about Asia than did Marco Polo, three or four centuries earlier. In America the whole vast area west of the Mississippi River was unknown in 1800. The coast of Australia had not yet been traced, and nothing was known of its interior. At that time South America was better known than any other of the continental land masses, except Europe; now it is the least explored of all. The nineteenth century, wonderful for advancement in many fields of human endeavor, was a marvelous one for the growth of geographical knowledge. As we stand in the doorway of the twentieth century, there is scarcely one eleventh of the land area of the whole earth that remains unexplored. Lewis and Clark pushed their way through the unknown vastness of the American Northwest; Livingstone and Stanley penetrated the dark continent of Africa; and in September, 1909, Lieut. Robert E. Peary of the United States Navy startled civilization by announcing his discovery of the North Pole. With the exception of a few interior tracts to-day, the only portions of the earth unknown and unmapped lie around the poles, and these are being rapidly sought out and brought to knowledge. Of all geographical conquests, by far the greatest is the discovery of America by Christopher Columbus in 1492 A.D. The story of Columbus is one of the most interesting and pathetic in history. It is a story of toil, hardship, perseverance, and great success, requited with disappointment and disgrace. Christophoro Colombo was born in Genoa, Italy, about 1435 or 1436 A.D. Following the custom of those times in giving names Latin forms, his name became Christopher Columbus. In Latin the word _columba_ means "dove." His father was a wool-comber who was wealthy enough to send his son to a university, where he studied mathematics and astronomy. On leaving the university, he worked a few months at his father's trade, but when he was fifteen years old he determined to be a sailor.