Benjamin Banneker was born in 1731 near Baltimore. His grandmother, English, taught him to read and write. For several winters, he attended a small school open to blacks and whites. There, he developed a keen interest in mathematics and science. Later, while working in agriculture, Banneker continued his studies of mathematics and taught himself astronomy. In 1753, he created a remarkable clock. He built it entirely out of wood, carving each gear by hand. His only models were a pocket watch and an old clock picture. The clock kept almost perfect time for over fifty years. In 1791, Banneker served as assistant to Major Andrew Ellicott, the surveyor appointed by President George Washington.