Napier’s Bones

There are slides devoted to this topic: Lecture 2, pp. 18-26.


The “Napier’s Bones (Napier’s Rods)” article provides a detailed look into the history and significance of Napier’s Bones, as well as an explanation of how to multiply and divide using the the rods.

For another explanation of how to calculate with the Bones, visit Wolfram Alpha’s page on Napier’s Bones.

The Computer History Museum’s page on Napier’s Bones briefly discusses the possible origins of the computational aid, and Napier’s adoption of the tool. It also provides depictions of Napier’s Bones and its Mexican cousin, the Sumador Chino.

Other Media

Watch the video Napier’s Bones: How They Work” for a concise and comprehensible explanation of how to multiply using the Bones.

Journal Articles

IEEE: “From Napier to Lucas: The Use of Napier’s Bones in Calculating Instruments,” M.R. Williams. This article explains the way Napier’s Bones worked, as well as the ways they were incorporated into the Calculating Clock and other calculating machines, as well as other ways the use of the Bones was extended.


The Universal History of Computing, Georges Ifrah, pp. 111