The method which Napier terms "Rabdologia" consists in the use of certain numerating rods for the performance of multiplications and divisions.
These rods, which were commonly called "Napier's bones," will be described further on.
In 1623 Ursinus published Rhabdologia Neperiana at Berlin, and the rods or bones were described in several other works.
With respect to the calculating rods, he mentions in the dedication that they had already found so much favour as to be almost in common use, and even to have been carried to foreign countries; and that he has been advised to publish his little work relating to their mechanism and use, lest they should be put forth in some one else's name.
The figures as written down are 12510 6255 14595 1534560 Napier's rods or bones consist of ten oblong pieces of wood or other material with square ends.
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