By hand, a slave could clean about a pound of cotton a day.

Working by hand, a slave could clean about a pound of cotton a day. But the Industrial Revolution was underway, and the demand was increasing. Large mills in Great Britain and New England were hungry for cotton to mass produce cloth. As the story was told, Whitney had a "eureka moment" and invented the gin, short for engine. The truth is that the cotton gin already existed for centuries in small but inefficient forms. In 1794, Whitney simply improved upon the existing gins and then patented his "invention": a small machine that employed a set of cones that could separate seeds from lint mechanically, as a crank was turned.