The following links provide additional information on John Napier and his “bones”:
John Napier < http://www-history.mcs.st-and.ac.uk/Biographies/Napier.html > is a biography of Napier from the very useful MacTutor History of Mathematics Archive maintained by the University of St. Andrews in Scotland. It has links to other references.
The Science Museum in London has several sets of "Napier's bones" in its collection.
Three images of a boxed set of Napier’s bones (circa 1690):
Six images of two sets of cylindrical "Napier’s rods" (circa 1671-1700):
Brass Napier’s bones (17th century):
Ivory Napier’s bones (18th century):
Finally, be aware that slide rules have sometimes been referred to as Napier’s bones. An internet search will sometimes lead you to slide rule information instead of the tool described in this article.
Thanks to Wayne Anderson of Gannon University’s Center for Excellence in Teaching and Learning for his help with the Napier’s bones Flash animation at < http://ww2.gannon.edu/cetl/caulfield/NapierBones.html >