Napier’s rods

The mathematician John Lord Napier of Merchiston (1550-1617), famed for his work on logarithms, is the inventor of this simple aid for multiplication consisting of square-sectioned rods, each with the multiples of a particular digit inscribed as a column on one face. By juxtaposing these rods in a certain prescribed way, one can easily multiply a number with several digits by a single-digit number, whereby the intermediate results can be easily read off and added into the next step. Division is also possible. Napier’s rods were an important and widely used aid for multiplication and division. They were in use well into the 19th century, particularly in France where they were known as Genaille’s rods. This set of rods was probably made in England around 1700. The box dates from the 19th century.