E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
is produced by multiplying together the lunar cycle, the solar cycle, and the Roman indiction. The first year of the Christian era corresponded to the year 4713 of the Julian, and therefore to reduce our B.C. dates to the Julian, we must subtract them from 4713, but our A.D. dates we must add to that number. So named from Julius Scaliger, the deviser of it.
Julian period. Multiply 28 by 19 and by 15, which will give 7,980, the time when the solar and lunar periods agree.