This is one of the best all around sites that I have found. It is titled “The MacTutor History of Mathematics Archive.”
http://www-history.mcs.st-and.ac.uk/~history/
This is an award-winning site that links to all sorts of mathematics information.
http://archives.math.utk.edu/
This site explains how Napier’s bones work.
http://www.youtube.com/watch?v=3gjDfc2AF3w
Napier:
http://www-history.mcs.st-and.ac.uk/~history/Mathematicians/Napier.html