American sculptor, painter, and illustrator Alexander Calder (1898-1976), through his construction of wire mobiles, pioneered kinetic sculpture.

Alexander Calder was born in Philadelphia, the son of a well-known sculptor and educator and his wife, a talented painter. Calder's grandfather, also a sculptor, executed the figure of William Penn that graces the dome of the city hall in Philadelphia. Though he was brought up in an artistic atmosphere, Calder's own inclinations were mechanical. He trained as a mechanical engineer at the Stevens Institute of Technology in New Jersey, studying such things as descriptive geometry, mechanical drawing, and applied kinetics--the branch of science that deals with the effects of force on free-moving bodies--in preparation for receiving his degree in 1919.

After working at a number of jobs that allowed him time for travel and reflection over the next few years, Calder decided to explore his growing interest in art. In 1923, two...