Cotton gin, machine that separates cotton fibers from the seeds, leaves, and other unwanted matter. Invention of the cotton gin in 1793, attributed to Eli Whitney, revolutionized the cotton industry in the South. Within 50 years cotton production had increased a thousand-fold. The original machines were of very simple design. A rotating drum with fine wire spikes, turned by hand, drew the fibers through narrow slots in a wire grid. The grid allowed the cotton fibers through, but not the seeds. A set of revolving brushes removed the fibers from the drum to prevent matting and clogging. The basic design of cotton gins has changed little since the 18th century. Modern mechanized versions use blasts of air to remove the fibers and are capable of producing a 500-lb (227-kg) bale of compressed cotton in little more than 10 min.
See also: Whitney, Eli.