1898: Sculptor Alexander Calder, best known for his mobiles and innovative wire structures, was born in Pennsylvania. Although his mother was an accomplished painter and his father an accomplished sculptor, the younger Calder began his career as an engineer. He earned a degree in mechanical engineering in 1919 and held several jobs in that field before he began taking art classes at the Art Students League in New York City in 1923. Calder subsequently ventured into commercial illustration, covering prize-fights and the circus for the National Police Gazette. He then traveled to Paris, where he began experimenting with sculpture. The artist made his first motor-driven sculptures, which were later dubbed "mobiles," in the winter of 1931-32. (Source: Library of Congress)