Mathematics 
Arithmetic

Written by Ephraim Chambers

Thursday, 01 January 1728 09:00 
among the Antients, was a kind of Cupboard, or Buffet. See BUFFET.
In this Sense Livy, describing the Luxury into which the Romans degenerated after the Conquest of Asia, says, They had their Abaci, Beds, &c. plated over with Gold. Dec. IV. Lib. ix.
The Word is Latin, but form'd from the Greek, άβαξ ; which among that People signify'd the same thing. Guichart goes higher : He derives άβαξ, from the Hebrew ךכא, extolli, to be elevated, rais'd ; and supposes its primary Signification to be a high Shelf, or other Convenience for things to be laid upon out of the way.
Abacus was particularly us'd among the Mathematicians, for a little Table strew'd o'er with Dust, on which they drew their Schemes and Figures. And hence the Abacus Pythagoricus, a Table of Numbers, contriv'dsor the ready learning of the Principles of Arithmetic ; denominated from its Inventor Pythagoras.
Hence also, from an Agreement in point of Use, the Karnes Abacus and Abaco, are us'd among the English and Italians for an Alphabet, or A B C, &c.
The Abacus Pythagoricus was, in all probability, no other than what we call MultiplicationTable. See TABLE.
Ludolsus and Wulsius give us Methods of performing Multiplication without the help of the Abacus; but they are too operose in ordinary Cases for Practice. See MULTIPLICATION.

