Napier's Rods
notes: label: Description
content: In a book published in the year of his death, Scottish mathematician and laird John Napier (1550-1617) described several aids to arithmetic computations. One, since known as Napier’s rods or Napier’s bones, was a set of rods marked with the multiples of the digits from 0 to 9. Napier explained how to use these rods to assist in multiplication and division and, with the use of a special additional rod, take square roots and cube roots.
label: Description
content: This set of Napier’s rods contains ten short wooden number rods with square cross section, and an eleventh, wider rod for square and cube roots. Each face of each number rod contains the first ten multiples of a digit. Each square containing a multiple is divided diagonally, with the tens value of the number written in the upper left corner and the ones value in the lower right corner. The number rods have multiples of the following numbers:
label: Description
content: 3 rods have multiples of 0, 1, 9, and 8
label: Description
content: 2 rods have multiples of 1, 5, 8, and 4
label: Description
content: 3 rods have multiples of 3, 2, 6, and 7
label: Description
content: 2 rods have multiples of 3, 4, 6, and 5
label: Description
content: Four digits on the top of each rod indicates which multiples it contains. The sum of the digits whose multiples are on opposite sides of a rod always totals 9. All four of these types of rods are described in Napier's <I>Rabdology</I>. However, Napier suggested using ten distinct rods. The digits on the larger rod do follow Napier's description. The rods fit in a red leather-covered case.
label: Description
content: For accounts of the use of the rods, see Napier, Bryden, or online sources. Napier also discovered logarithms, which had a more lasting influence on calculations as they came to be embodied inan instrument called the slide rule.
label: Description
content: This set of rods was acquired by purchase. The case is a modern reproduction produced by the vendor.
label: Description
content: References:
label: Description
content: John Napier, <I>Rabdology</I>, trans. William F. Richardson with an introduction by Robin Rider, Cambridge, Mass.: MIT Press and Los Angeles: Tomash Publishers, 1990.
label: Description
content: D.J. Bryden, <I>Napier's Bones: A History and Instruction Manual</I>, London: Harriet Wynter Publications, Ltd., 1992.
label: Description
content: Accession file.
label: Location
content: Currently not on view
place: label: place made
content: United Kingdom: Grand Bretagne
topic: label: Subject
content: Mathematics
setName: label: See more items in
content: Medicine and Science: Mathematics
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: MA.316584
label: catalog number
content: 316584
label: accession number
content: 225998
objectType: label: Object Name
content: calculating rods
physicalDescription: label: Physical Description
content: wood (overall material)
label: Physical Description
content: leather (overall material)
label: Measurements
content: overall: 2.3 cm x 9.8 cm x 7.4 cm; 29/32 in x 3 27/32 in x 2 29/32 in