Creative Crafthouse Napiers Bones - Base, Cover, 2 Full Sets of Rods with Square Root Bone and Cube Root Bone-John Napier Math Calculator from 1617 Invented by John Napier, Scottish mathematician, in 1617. In common use for nearly 3 centuries as a math calculaor Base is 7" x 7" ; rods 6" long. Set comes with 20 rods - 2 full sets of #0-9 This set will include the Square root and Cube root bones. Available on our other Napier listing you can find the same set without the extra 2 bones (lower cost) Made in Spring Hill, Florida by CreativeCrafthouse