Abacus

A calculating frame used for arithmetical calculations in ancient Greece, ancient Rome and later, up to the 18th century, in Western Europe. The frame was subdivided into strips, inside which the counters (bones, pebbles, etc.) were moved. The Chinese equivalent of the abacus — swan-pan — was used in the Far East, while the "schetyschety" was employed in Russia.

In nomography, an abacus is a special sketch (the so-called net chart nomogram).

References

[a1]	W.W. Rouse Ball, "A short account of the history of mathematics", Dover, reprint (1960) pp. 123–125