ABSTRACT
The basic abacus consists of a rectangular frame, generally made out of wood, in which the two longer sides are joined by a series of equally spaced columns, on each of which is threaded a numberalways the same-of beads. The actual operation of the abacus depends upon these being moved up and down by the user, so it is not surprising that the Japanese word shuzan means, simply, ‘bead calculation’. The abacus, in its most elementary form, seems to be hardly more than a children’s toy of a kind to be found in many different parts of the world. An instrument operating on the same principle could equally consist of pebbles to be moved up and down the columns of a matrix imprinted in sand, or along parallel grooves cut into a wooden board. Such isomorphic instances are well documented.1
