Napier Bio   http://www-gap.dcs.st-and.ac.uk/~history/Mathematicians/Napier.html
Stevinus Bio   http://www-gap.dcs.st-and.ac.uk/~history/Mathematicians/Stevin.html

"Seeing there is nothing that is so troublesome to mathematical practice, nor that doth more molest and hinder calculators, than the multiplications, divisions, square and cubical extractions of great numbers ... I began therefore to consider in my mind by what certain and ready art I might remove those hindrances."
Mirifici logarithmorum canonis descriptio (Napier)

"It teaches (to speak in a word) the easy performance of all reckonings, computations and accounts, without broken numbers [common fractions], which can happen in man's business, in such a sort as that the four principles of arithmetic, namely addition, subttraction, multiplication and division, by whole numbers may satisfy these effects."
Introducing decimals in De Thiende (Stevinus)

Napier Links
Napier's Bones   http://pages.cpsc.ucalgary.ca/~williams/History_web_site/time%201500_1800/Napier's%20bones.htm
Intro to Slide Rule (Napier)   http://www.sliderule.ca/intro.htm

Stevinus Links
Original Text DISME The Art of Tenths   http://home.wxs.nl/~hopfam/Dime.html
A Description of the Admirable Table of Logs by Napier   http://www.ru.nl/w-en-s/gmfw/bronnen/napier1.html

 

 Napier and His Calculating Bones

1550 - 1617 AD in Edinburgh, Scotland

Simon Stevin Invents the Decimal

1550 - 1620 AD in Flanders and The Hague, Holland