Set of thirty Napier's brass Rods in tin case, (three of the rods signed 'Geo Brown'), by George Brown, Scotland, 1670-1699. From the Library of the Lord Napier and Ettrick (see note).
John Napier, well known as the inventor of logarithms, also invented a device ‘for the sake of those who prefer to use natural numbers’ in 1617. They were described as ‘the bones, by which multiplication and division is performed by addition and subtraction without charging the memory’. Each rod has a multiplication table running downwards. The rods are lined up against a template which has the numbers from 1 to 10 also running downwards. The number along the top of the rods can be multiplied by any of those on the template by addition of the numbers in that row on the rods.