Set of Napier's bones of wood, invented by John Napier of Merchiston for the purpose of performing mechanically the operations of multiplication and division, in original box, 18th century

Set of Napier's bones of ivory in a small leather case, c. 1650

Set of Napier's bones in boxwood, a device for performing arithmetic, particularly multiplication, invented by John Napier of Merchiston, Edinburgh, who also developed logarithms, 18th century

Set of Napier's bones, ten, used for demonstration of multiplication and division

Napier's Bones, Les Reglettes Financieres, simplifier of finances and commerce, ten wooden rods numbered '0' to '9', in cardboard box with one fixed wooden index rod, made by Eugene Belin et Fils of Paris, c. 1885

Napier's Bones, Les Reglettes Multisectrices, simplifier of division, ten wooden rods numbered '0' to '9', in cardboard box with one fixed wooden index rod, made by Eugene Belin et Fils of Paris, c. 1885

Napier's Bones, Les Reglettes Multiplicatrices, simplifier of multiplication, ten wooden rods numbered '0' to '9', in cardboard box with one fixed wooden index rod, made by Eugene Belin et Fils of Paris, c. 1885

Set of slip-form Napier's bones with tabulat and case, wood, presumably British, 1650 - 1750