Description

ORIGINAL SET OF NAPIER’S CALCULATING RODS, English, late 17th / early 18th century, of variously toned boxwood throughout, contained in the original 4-1/8″ x 2-5/8″ x 5/8″ (10.4 x 6.5 x 1.7 cm) case with lovely incised geometric decoration to both sides. This fine all-original set comprises 16 four-sided calculating rods, the tabulat carrier, wood case and slide-off lid. All the numerals are punched, and in an interesting idiosyncrasy the maker had mis-labeled four of the “4” multiplication table columns as “8”, and then corrected them. The numeral punches all match, and the set is absolutely complete and all original, and in very fine condition. This set was made with a full 16 rods (for multiplying very large numbers), instead of supplying a square/cube rod. Inscribed in ink in the tabulat is a tally of the number of sides available (either 6 or 7) for each digit from 0 to 9, for the total of 64 sides.

In 1617 John Napier (1550 – 1617), of Merchiston, Scotland, published Rabdologiae, in which he revealed his newly invented calculating rods capable of rapid multiplication of very large numbers. Each “bone” is finely punched with a multiplication table for the integer on top multiplied by 1, 2, …9. Diagonal lines show how to carry the second and further digits. The four sides of each bone present tables for four different integers. Thus one can multiply numbers up to 16 digits long with this set!