Napier's bones

Napier’s bones - a device to facilitate calculation invented by John Napier in the seventeenth century - are now unbreakable.

In Hudibras: "A moon-dial, with Napier's bones, And several constellation stones."

Step by step improvements were made; the most important being that invented by Napier of Merchiston, the inventor of logarithms, commonly called Napier's bones, consisting of a number of rods divided into ten equal squares and numbered, so that the whole when placed together formed the common multiplication table.

It would perhaps be rank heresy to suppose that Sir Walter did not know that ``Napier's bones'' were an apparatus for purposes of calculation, but he certainly puts the expression in such an ambiguous form that many of his readers are likely to suppose that the actual bones of Napier's body were intended.

Goldsmith—French memoir writers— Historians—Napier's bones—Mr. Gladstone— Lord Macaulay—Newspaper writers—Critics .