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This Week in History

March 11-17, 1794:
Eli Whitney and the Machine Tool Principle

March 2012

Cotton Mather
Eli Whitney, painted by Samuel Morse.

On March 14, 1794, Eli Whitney received a patent on an invention which he had designed and built in ten days as a favor to his hostess. But the cotton gin ("gin" being a contraction of "engine") yielded much aggravation and very little profit for its inventor, and Whitney turned his creative energies elsewhere, to the great benefit of the United States.

Whitney grew up on a Massachusetts farm where he spent his spare time repairing violins, working with iron, and, during the American Revolution, making nails in his father's small workshop. He earned enough money by the age of 23 to pay for tuition at Yale, where he studied law, but preferred the science and mathematics courses. He supplemented his earnings by repairing the college's scientific apparatus and equipment. One of these was an orrery which had been ordered by Yale's president Ezra Stiles from London. It had arrived damaged and was about to be shipped back for repairs, but Whitney spent a week making special tools, and had it working perfectly.

After his graduation in 1792, Whitney needed time to prepare for the bar, so he accepted a tutoring position in Georgia. On the ship taking him there, he met Catherine Greene, the widow of Revolutionary War General Nathanael Greene, who was returning with her children to Savannah. When his tutoring job did not materialize, Whitney was invited to the Greene home, where he studied his law books and made himself useful by repairing farm implements. Many of General Greene's former officers still congregated at the Greene home, and they talked about the difficulty of separating green-seed cotton fiber from its seeds.

Mrs. Greene told them that Whitney could solve any mechanical problem, and so, to please her, he built an efficient cotton gin. Formerly, it had taken a full day to produce a pound of cotton by separating the seeds by hand. With the improvements he added by April of 1793, Whitney's gin could produce 50 pounds of cleaned cotton in a day. Greene's former officers were ecstatic, and began expanding their cotton fields, while Whitney planned to continue his law studies. But Phineas Miller, the Greenes' plantation manager, persuaded Whitney to patent the gin, and to go into partnership with him to produce it.

Even before Whitney left Savannah to apply for a patent and to build a factory, his gin had been carefully scrutinized by others and imitations began to appear. Nevertheless, Whitney went to New Haven, Conn., erected a factory, and trained the workers. But epidemics of scarlet fever and yellow fever swept through New Haven in the summer of 1794, forcing Whitney to close his shop. Then, in 1795, a fire broke out which destroyed almost everything. Whitney rebuilt, but he was making little profit on his invention due to the many pirated versions, and, coming from a farm family, he did not have cash reserves to draw on.

But in 1798, war with France seemed to loom on the horizon, and the American government was signing contracts for musket production with private manufacturers. The United States had set up a Federal armory at Springfield, Mass. in 1794, and another at Harpers Ferry, Va. in 1798, but production was slow because guns were mainly hand-crafted objects. Therefore, in the military emergency, the Administration of President John Adams was placing musket orders with as many private contractors as possible.

Although he had never made a firearm, Eli Whitney tendered a bid on June 14, 1798 to produce 10,000 "stands of arms" (a musket and its bayonet and ramrod) to be delivered within 28 months at a cost of $134,000. This was an unheard-of number of muskets in an incredibly short period, and it represented a conscious government investment in a new method of production. Whitney's coadjutator in this plan was Vice President Thomas Jefferson.

When Jefferson served as Ambassador to France during 1785-1789, he had witnessed the production system of interchangeable parts for firearms which had been designed by Honoré Blanc. Jefferson had tried everything in his power to get Blanc to emigrate to the United States, but had failed. Whitney, too, envisioned a new method of production which would involve an assembly line with machines run by water power, production tasks broken down into their component parts, unskilled workers trained to use the machines, and the milling of interchangeable parts so that guns could be quickly and easily made and repaired.

Whitney realized the difficulties involved when he met with Jefferson, but he was convinced that it eventually could be done. In his bid, he wrote that he proposed to manufacture guns by a new method, his aim being "to make the same parts of different guns, as the locks, for example, as much like each other as the successive impressions of a copper-plate engraving." The difficulty was, Whitney said, that "A good musket is a complicated engine and difficult to make—difficult of execution because the conformation of most of its parts correspond with no regular geometrical figure."

Whitney carried on a correspondence with Secretary of the Treasury Oliver Wolcott, in which he laid out his conceptions for manufacturing. In May of 1798, he wrote, "I am persuaded that Machinery moved by water adapted to this Business would greatly diminish the labor and facilitate the manufacture of this Article. Machines for forging, rolling, floating, boring, grinding, polishing, etc., may all be made use of to advantage." After a year of constructing his factory and training his workers, he again wrote to Wolcott that, "One of my primary objectives is to form the tools so that the tools themselves shall fashion work and give to every part its just proportions, which once accomplished, will give exceptional uniformity to the whole."

Because of Whitney's excellent reputation, ten New Haven backers provided him with $10,000 in working capital, which was added to the $5,000 from the government when the contract was signed. Whitney began building his factory north of New Haven, on Mill River, which provided the power. By May of 1799, his main factory building had been completed and the waterworks were nearly ready. Whitney spent much time designing the machine tools that would be used by his employees, and on training the men to use them. He provided houses for his workers, which included attached acres which were used for planting crops.

The large preliminary design and construction effort which went into setting up Whitney's armory meant that he could not deliver the muskets on schedule. In January, 1801, he travelled to Washington, D.C., and demonstrated to President John Adams and members of the U.S. military that it was possible to produce interchangeable parts. The musket parts had been largely produced by machine, but some hand filing had been needed to make them truly interchangeable. When Thomas Jefferson became President a few months later, he consistently backed Whitney in order to obtain the system of manufacturing which he had seen demonstrated in France. By the time Whitney delivered the last of the 10,000 muskets in January of 1809, his manufacturing system was being adopted by both Federal arsenals.

Manpower, especially skilled manpower, was scarce in the new republic, and so Whitney relied on training unskilled workers. To enable his workmen to perform one "single and simple operation" at a time, Whitney designed a series of "jigs and fixtures" which fixed the parts and tools into their relative positions for each operation so that the cutting of the part by the tool would be correct and consistent. The division of labor within the Whitney Armory was not so much by part of the musket worked on as it was by function. A workmen using a drill might drill many parts, and might drill the same part again and again in different places as it followed through the process of production.

Whitney also realized that he needed to develop skilled workers, and he often noted that he was making armorers as well as arms. He encouraged the adoption of useful practices from other armories, and often visited Harpers Ferry and Springfield to exchange ideas. There was constant testing in order to develop uniformity, and this applied to uniformity within the Whitney Armory as well as between private armories and the Federal armories.

When Whitney died in 1825, his armory still had not developed complete interchangeability by the machining of parts, but just two years later, the Federal armory at Harpers Ferry did accomplish Whitney's and Jefferson's goal.