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Mathematical Treasure: 17th-Century Napier Rods

Frank J. Swetz (Pennsylvania State University)

This is a 17th century set of Napier rods used for multiplication. Their maker is unknown. The 4 and 9 rods are missing.

Napier rods may be John Napier's second most famous invention, after logarithms. For more about John Napier (1550-1617) and Napier rods, see the MAA Convergence article, "John Napier: His Life, His Logs, and His Bones," which includes an example of how to use Napier's rods, also known as "Napier's Bones."

Source: Oughtred Society, Archive of Collections, Tom Wyman Collection. Tom Wyman (1927-2014) was the first president of the Oughtred Society. Wyman assembled an extensive collection of early slide rules and books related to them. The image above is Item #220 in the Wyman Collection.

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Frank J. Swetz (Pennsylvania State University), "Mathematical Treasure: 17th-Century Napier Rods," Convergence (June 2018)