Napier's Bones - Card Abacus

Card Abacus

In addition to the previously-described "bones" abacus, Napier also constructed a card abacus. Both devices are reunited in a piece held by the Spanish National Archaeological Museum, in Madrid.

The apparatus is a box of wood with inlays of bone. In the top section it contains the "bones" abacus, and in the bottom section is the card abacus. This card abacus consists of 300 stored cards in 30 drawers. One hundred of these cards are covered with numbers (referred to as the "number cards"). The remaining two hundred cards contain small triangular holes, which, when laid on top of the number cards, allow the user to see only certain numbers. By the capable positioning of these cards, multiplications can be made up to the limit of a number 100 digits in length, by another number 200 digits in length.

In addition, the doors of the box contain the first powers of the digits, the coefficients of the terms of the first powers of the binomial and the numeric data of the regular polyhedra.

It is not known who was the author of this piece, nor if it is of Spanish origin or came from a foreigner, although it is probable that it originally belonged to the Spanish Academy of Mathematics (which was created by Philip II) or was a gift from the Prince of Wales. The only thing that is sure is that it was conserved in the Palace, of where it was passed to the National library and later to the National Archaeological Museum, where it is still conserved.

In 1876, the Spanish government sent the apparatus to the exhibition of scientific instruments celebrated in Kensington, where it received much attention, up to the point at which several societies consulted the Spanish representation about the origin and use of the apparatus. This motivated D. Felipe Picatoste to write a monograph, that was sent to all the nations, in which he expressed surprise about the fact that the abacus was only well-known in "England, country of origin of its inventor" (though of course he originated in Scotland).