(1) A flat polished surface or tablets, strewn with sand, on which
figures were inscribed with a stylus.
(2) A polished tablet divided longitudinally into nine columns (or more)
grouped in threes, with which counters were used, either plain or marked
with signs denoting the nine numerals, etc.
(3) Tablets or boxes containing nine grooves or wires, in or on which
ran beads.
(4) Tablets on which nine (or more) horizontal lines were marked, each
third being marked off.
The only Greek counting board we have is of the fourth class and was
discovered at Salamis. It was engraved on a block of marble, and
measures 5 feet by 2½. Its chief part consists of eleven parallel lines,
the 3rd, 6th, and 9th being marked with a cross. Another section
consists of five parallel lines, and there are three rows of
arithmetical symbols. This board could only have been used with counters
(_calculi_), preferably unmarked, as in our treatise of _Accomptynge by
Counters_.