a reference to the ancient calendar devised and used by the Romans. Very early in their history, the Romans began basing their calendar on the idea that 12 lunar months make a year. Each lunar month (from new moon to new moon) is about 29 1/2 days, so the Roman year came to 354 days. But the true solar year (the time it takes the Earth to circle the sun) is just under 365 1/4 days. The Romans made up for the difference by adding an extra month every few years. —SHSBC Binder 22 Approved Glossary