ALEXANDER CALDER (1898-1976) Credited with the invention of the mobile, Alexander Calder revolutionized twentieth-century art with his innovative use of subtle air currents to animate sculpture. Calder was prolific and worked throughout his career in many art forms. An accomplished painter of gouaches and sculptor in a variety of media, Calder is best known for poetic arrangements of boldly colored, irregularly shaped geometric forms that convey a sense of harmony and balance. He also designed jewelry, tapestry, theater settings and architectural interiors. From the 1940s on, Calder's works, many of them large-scale outdoor sculptures, have been placed in virtually every major city of the Western world.