An 18th century set of Napier's Bones
Napier's bones is a manually-operated calculating device created by John Napierof Merchiston for calculation of products and quotients of numbers. The method was based on Arab mathematics and the lattice multiplication used by Matrakci Nasuh in the Umdet-ul Hisab[1] and Fibonacci's work in his Liber Abaci. The technique was also called Rabdology (from Greek ῥάβδoς [r(h)abdos], "rod" and -λογία [logia], "study"). Napier published his version in 1617 in Rabdologiæ, printed in Edinburgh, Scotland, dedicated to his patron Alexander Seton.[2]
Using the multiplication tables embedded in the rods, multiplication can be reduced to addition operations and division to subtractions. More advanced use of the rods can even extract square roots. Note that Napier's bones are not the same aslogarithms, with which Napier's name is also associated.