# Rabdologiæ, seu numerationis per virgulas libri duo

Napier, John
A. Hart, Edinburgi, 1617
107. Napier later extended his use of logarithms in a mecahnical form in this book. He devised a simple method of multiplying and dividing using small rods called "Napier's bones." These rods became the basis for what later became the slide rule.