At thirty years old, he made a clock, which proved an excellent timepiece. He had never seen a clock, for nobody in that region had such an article; but he had seen a watch, and it occupied his thoughts very much. It seemed to him such a curious little machine, that he was very desirous to make something like it. The watch was made of gold and silver and steel; but Benjamin Banneker had only wood for material, and the rudest kind of tools to work with. It was a long while before he could make the hand that marked the hours, and the hand that marked the minutes, and the hand that marked the seconds, correspond exactly in their motions; but by perseverance he succeeded at last. He was then about thirty years old. This was the first clock ever made in this country. It kept time exactly, and people began to talk about it as a wonderful thing for a man to do without instruction. After a while, the Ellicott family, who owned the Mills, heard of it, and went to see it. Mr. Elias Ellicott, a merchant in Baltimore, became very much interested in the self-taught machinist. He lent him a number of books, among which were some on astronomy,--a science which treats of the sun, moon, and stars. Banneker was so interested in this new knowledge that he could think of nothing else. He sat up all night to watch the planets, and to make calculations about their motions. Mr. Ellicott went to see him to explain to him how to use some of the tables for calculations contained in the books he had lent him; but he found, to his great surprise, that the earnest student had studied them all out himself, and had no need of help. It was not long before he could calculate when the sun or the moon would be eclipsed, and at what time every star would rise and set. He was never known to make a mistake in any of his astronomical calculations; and he became so exact, that he pointed out two mistakes made by celebrated astronomers in Europe.