The New Student's Reference Work/Abacus
Abacus (ăb′ă-cŭs), is the classic name for what is now often called in schools the bead frame, a device for counting by means of beads or discs which have been strung upon parallel wires. Such a machine was in use among the Greeks and Romans. The Chinese and the Persians employ it to this day. In architecture, an abacus is the flat tablet above the capital of a column.