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Moldboard Plow

Thomas Jefferson had an abiding interest in improving the technology of farming. One of his more important contributions to agriculture was the "mouldboard of least resistance" for a plow.1

A modern recreation of Jefferson''s "mouldboard plow of least resistance." Thomas Jefferson Foundation, Inc.While serving as minister to France, Jefferson had the opportunity to observe European plow designs. Their deficiencies inspired him to set down in a 1788 memorandum his plans for an improved moldboard, the wooden part of the plow that lifts up and turns over the sod cut by the iron share and coulter.2 He wished to make that lifting and turning action as efficient as possible, so that the plow could be pulled through the soil with the least expenditure of force. He brought his love of mathematics to his design, which he declared was "mathematically demonstrated to be perfect."3

By 1794, Jefferson had put his plans into action at Monticello. He had a plow fitted with a wooden moldboard of his design and later reported to Sir John Sinclair that "an experience of 5. years has enabled me to say it answers in practice to what it promises in theory." In addition to offering the least resistance as it was pulled through the soil, Jefferson's moldboard had a further advantage: "[I]t may be made by the coarsest workman, by a process so exact, that it's form shall never be varied a single hair's breadth." Ease of duplication was thus another measure of the usefulness of his design.4

Jefferson''s drawing for the Moldboard Plow of Least Resistance

In 1814, Jefferson began to have his moldboards cast in iron. He informed Charles Willson Peale that the plow with his iron moldboard was "so light that two small horses or mules draw it with less labor than I have ever before seen necessary. it does beautiful work and is approved by every one."5

Just how widely Jefferson's moldboard was adopted by others is unclear. He never sought to patent it, and in fact sent numerous models to friends at home and abroad, where his design met with general approval. Jefferson's moldboard was featured in James Mease's Domestic Encyclopedia (Philadelphia, 1803), and the French Society of Agriculture awarded Jefferson its gold medal and membership as a foreign associate.6

- Russell L. Martin and Lucia C. Stanton, 10/88

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