Cotton gin

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A cotton gin on display at the Eli Whitney Museum.

A Cotton Gin (short for cotton engine) is a machine that quickly and easily separates the cotton fibers from the seedpods and the sometimes sticky seeds, a job previously done by workers. These seeds are either used again to grow more cotton or, if badly damaged, are disposed of. It uses a combination of a wire screen and small wire hooks to pull the cotton through the screen, while brushes continuously remove the loose cotton lint to prevent jams. The term "gin" is an abbreviation for engine, and means "machine". Eli Whitney also had the idea for interchangeable parts which was later implemented by weapons manufacturers and industry at large.

Diagram of a modern gin plant - courtesy USDA

[edit] Invention

According to Joseph Needham, a precursor to the cotton gin known as a charkhi was already present in India. The charkhi had two elongated worms that turned its rollers in opposite directions.^[1] The Indian churka was effective at separating seeds from the varieties of cotton grown there, and possibly for some of the long staple, Sea Island cotton (Gossypium barbadense), but was inadequate for processing the short staple, green seed cotton (Gossypium hirsutum) cultivated in upper South Carolina and Georgia.

The modern cotton gin was later created by the American inventor Eli Whitney in 1792 to mechanize the production of cotton seeds. The invention was granted a patent on March 14, 1794. The gin was credited for increasing assets in the American jobs.

Cotton gin patent, March 14, 1794

There is slight controversy over whether the idea of the cotton gin and its constituent elements are correctly attributed to Eli Whitney. The popular version of Whitney inventing the cotton gin is attributed to an article on the subject in the early 1870s and later reprinted in 1910 in the The Library of Southern Literature. In this article Andrews mentioned how Catherine Littlefield Greene suggested to Whitney the use of a brush-like component instrumental to separate out the seeds and cotton. Historians later explored this idea, and some consider that Catherine Littlefield Greene, Whitney's landlady, should be credited with the invention of the cotton gin, or at least with the original concept. Women were not eligible to receive patents in the early U.S., and Greene may have asked Whitney to obtain it for her. Patent office records also indicate that the first cotton gin may have been built by a machinist named Sean Paul two years before Whitney's patent was filed. Joseph Watkins, who resided near Petersburg, Georgia is credited by many historians as the first inventor of the cotton gin, and was using it on his plantation when he was visited by the frustrated Eli Whitney, who on seeing it went back to Savannah and soon developed his model which he patented. Watkins was urged to sue Whitney, but had no desire to engage in a controversy and never asserted his claim. Watkins was a planter of large means, who pursued the study and application of mechanics more for amusement than profit.

An engraving from Harper's Magazine from 1869 showing the first cotton gin

While the Watkins story had some romantic adherents, and still others have credited Hodgson Holmes, later publication of certain of Whitney's papers, including letters to his family during the invention process, showed the claims to be lacking foundation.

Many people attempted to develop a design that would process short staple cotton and Holmes was indeed issued a patent for an "Improvement in the Cotton Gin". However, the evidence indicates that Whitney did invent the saw gin, for which he is famous. Although he spent many years in court attempting to enforce his patent against planters who made unauthorized copies, a change in patent law ultimately made his claim legally enforceable—too late for him to make much money off of the device in the single year remaining before patent expiration.^[2]