Dictionaries of the Scots Language
Dictionars o the Scots Leid

Scottish National Dictionary (1700–)

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NAPIER. After John Napier of Merchiston, Edinburgh (1560–1617), mathematician. In various phrs., as Napier's bones (or rods), a series of bone rods used as a calculator, described (but not invented) by Napier in 1617, Napier's compass, a compass with a pen on one leg and a pencil on the other; Napier's diagram, a diagram on a compass card so arranged as to show magnetic deviation; Napier's (or Napeirian) logarithms, the form of logarithms worked out by Napier, orig. for sines, later applied to logarithms of numbers to the base e = 2.71828 . . .; Napier's rules, in the solution of spherical triangles, the sine of any part equals the product of the tangents of the adjacent parts or of the cosines of opposite parts. Under the spelling naper (which represents the Sc. pronunciation of the name [′nepər]), (1) a unit used in the comparative measurement, expressed in logarithms, of electrical power values or currents, = 8.686 decibels; (2) the name of a large crater in the moon.