Napier’s rods

This set of rods dates from the 18th century and was formerly owned by the Earls of Stanhope in Chevening, Kent. It was probably used by Charles, 3rd Earl of Stanhope (1753-1816), who, as Viscount Mahon, invented and constructed several 4-species [1 2] and one 2-species mechanical calculating machine during the years1774 and 1780. All items are made of boxwood and there are ten rods and also a triple-block for working with fractions and square roots. The slightly damaged box is, like others of its kind (in the British Museum, London, and the Whipple Museum, Cambridge, for example), decorated with a linear geometric ornament (a hexagonal star inscribed in several rings).