How It Works: Seed separation with Eli Whitney’s cotton gin
Countless American inventions have forever changed the face of agriculture. Need proof? Tour the National Agricultural Hall of Fame in Bonner Springs, Kan. There, you’ll find the mechanical reaper, gasoline-powered tractor, cream separator … the list goes on and on.
But few inventions had as much impact and notoriety as the cotton gin, invented and patented by Eli Whitney in 1794. Whitney’s invention of the cotton gin enabled one man to clean as much cotton in one day as could be cleaned in an entire winter by hand – earning Whitney a spot in the Ag Hall of Fame in 1977.
By the time Whitney invented his gin (an abbreviated form of the word engine), simple seed-removing devices had been around for centuries. However, most (including a machine developed in the East Indies) were designed to work with long-staple cotton. Unfortunately, long-staple cotton could only be grown along the coast or in some island nations. The one variety that could be grown inland was a short-staple variety with sticky green seeds that were time-consuming to pick out of the fluffy white cotton bolls.
Whitney’s invention, the first of its type, mechanized the seed separation process for this type of cotton. Whitney’s machine could generate up to 55 pounds of cleaned cotton daily, or approximately 55 times that cleaned by a field worker, making cotton production profitable for the southern states. As a result, the cotton gin boosted U.S. cotton exports from less than 500,000 pounds in 1793 to about 93 million pounds in 1803.
Ironically, the cotton gin did much more than make cotton growing a profitable venture for the southern states. It also played an unintended role in helping preserve slavery in the U.S. and, some have argued, initiating the Civil War. Prior to Whitney’s invention, cotton production required hundreds of man-hours to grow and pick the crop and separate cottonseed from raw cotton fibers. In fact, cotton was so time consuming and costly to produce that before the invention of the cotton gin, slavery had been on the decline, prompting some slaveholders to give away their slaves. After the invention of the cotton gin, the plantation slavery industry was rejuvenated … right along with the cotton market.
“While it was true that the cotton gin reduced the labor of removing seeds, it did not reduce the need for slaves to grow and pick the cotton,” says William Brown, director of the Eli Whitney Museum and Workshop in Hamden, Conn. “In fact, the opposite occurred. Cotton growing became so profitable for the planters that it greatly increased their demand for both land and slave labor.”
In 1790, Brown notes, there were six slave states; by 1860 there were 15. From 1790 until 1808 when Congress banned the importation of slaves from Africa, Southerners imported 80,000 Africans. By 1860, approximately one in three Southerners was a slave.
Unlike other agricultural commodities in the 1800s, cotton could be stored for long periods of time and shipped great distances with little chance of damage or spoilage. Consequently, it quickly became America’s largest export, representing more than half the value of all U.S. exports from 1820 to 1860. It was simply too much of an economic force for the South to give up – even though cotton was equally important to the New England economy.
Whitney got the idea for his cotton gin by observing the cotton cleaning process and studying the hand movements of slaves cleaning the cotton. “One hand held the seed while the other hand teased out the short strands of lint,” Brown explains. “The machine he designed simply duplicated this process.”
To take the place of a hand holding the seed, Whitney made a sort of sieve of wires stretched lengthwise. To do the work of the fingers pulling out the lint, Whitney had a drum rotate past the sieve, almost touching it. On the surface of the drum, fine, hook-shaped wires projected, catching at the lint and pulling it from the seed.
“Whitney’s original prototype was improvised with hooks shaped from the wire ribs of a bird cage,” Brown explains. “However, he quickly realized that only saw blades would be durable enough to tear out the lint. That was really all there was to Whitney’s cotton gin, and it never became any more complicated.”
To clean cotton using Whitney’s invention, cotton bolls were fed into the top of the machine as the wooden roller with its small spiky wire teeth was rotated by hand cranking. As the cylinder rotated, the teeth snared the boll’s cotton fibers and pulled the fiber strands through a grate. Slots in the grate were set too close together for cotton seeds to pass through. Fiber, meanwhile, was stripped away from the seeds by a rotating brush, allowing the seeds to be combed out of the cotton. The cotton was cleaned and baled using a separate machine and then shipped to textile factories.
Not much has changed in more than 200 years, except that the machines have gotten larger and have become mechanized. Gins today dry, moisturize, sort and clean the cotton before baling it into bundles, making it completely ready for sale. Thanks to electric power and high velocity air blasting, fully automated modern cotton gins produce 15 tons of cleaned cotton per hour.
Unfortunately, Whitney never got rich from the cotton gin and even lost money on the venture, according to Brown. “Patenting an invention and making a profit from it are often two different things,” he says. “After considering possible options for his invention, Whitney and his business partner, Phineas Miller, opted to produce as many gins as possible, install them throughout Georgia and the South, and charge farmers a fee for doing the ginning for them. Their charge was one-fifth of the finished product – paid to them in cotton itself.”
However, that’s where their troubles began, Brown says. Farmers resented having to use Whitney’s gins where they had to pay what they regarded as an exorbitant tax. Instead, planters made their own versions of Whitney’s gin.
Part of the problem was that the device was too easily copied. Those who understood the basic design could reproduce and sell it without needing a model or measured drawings in hand. Naturally, none of them paid Whitney his required royalties. “Phineas Miller brought costly suits against the owners of these pirated versions,” Brown says, “but because of a loophole in the wording of the 1793 patent act, they were unable to win any suits until 1800, when the law was changed.”
In the meantime, Whitney used most of his income fighting patent infringement suits. Although it was a brilliant and immediately successful invention, Whitney’s gin was a patent failure.
“Struggling to make a profit and mired in legal battles, the partners finally agreed to license gins at a reasonable price,” Brown says. “In 1802, the state of South Carolina agreed to purchase Whitney’s patent rights for $50,000 but payments were delayed. The partners also arranged to sell the patent rights to North Carolina and Tennessee. By the time even the Georgia courts recognized the wrongs done to Whitney, only one year of his patent remained. In 1808 and again in 1812 he humbly petitioned Congress for a renewal of his patent.”
Eli Whitney is best remembered as the inventor of the cotton gin. He is less often identified as a prophet of manufacturing organization. In 1798, he set out to apply division of labor through the artful construction of tools to manufacture muskets. Whitney had never made a gun in his life, but in 1798 he obtained a contract to deliver 10,000 muskets in 1800 in response to new conflicts between Great Britain, France and the U.S. The new American government, realizing the need to prepare for war, began to arm.
Ironically, it was as a manufacturer of muskets that Whitney finally achieved financial success. Up until the time he entered the firearm industry, each rifle was handmade from stock to barrel and gun parts were not interchangeable.
“It was Whitney’s idea to make all the parts to his rifles so nearly identical that the machine’s parts could be interchangeable from one gun to another,” Brown says. “For each part of the gun, a template was made. It was identical in principle to the dress pattern.” In essence, a worker would follow that pattern when cutting each piece of metal for the gun.
“If his genius led King Cotton to triumph in the South,” Brown muses, “it also created the technology with which the North won the Civil War.” FC
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Tharran Gaines is the author of five books on antique tractor restoration and writes a variety of materials for AGCO Corp. He is also a contributing editor to AGCO Advantage and Massey Ferguson Farm Life magazines for AGCO. E-mail him at firstname.lastname@example.org; online at www.gainescommunications.com.