A year determined by a certain number of phases of the moon, as opposed to the passage of the earth around the sun.
In Order To Put An End To The Disorders Arising From The Negligence Or Ignorance Of The Pontiffs, Caesar Abolished The Use Of The Lunar Year And The Intercalary Month, And Regulated The Civil Year Entirely By The Sun.
By Inserting, Therefore, Three Additional Months Instead Of Four In Every Period Of Eight Years, The Coincidence Between The Solar And Lunar Year Would Have Been Exactly Restored If The Latter Had Contained Only 354 Days, Inasmuch As The Period Contains 354X8 3 X 30 = 2922 Days, Corresponding With Eight Solar Years Of 3654 Days Each.
The lunations are supposed to consist of twenty-nine and thirty days alternately, or the lunar year of 354 days; and in order to make up nineteen solar years, six embolismic or intercalary months, of thirty days each, are introduced in the course of the cycle, and one of twenty-nine days is added at the end.
4711,...4714 X; The Common Solar Year Containing 365 Days, And The Lunar Year Only 354 Days, The Difference Is Eleven; Whence, If A New Moon Fall On The 1St Of January In Any Year, The Moon Will Be Eleven Days Old On The First Day Of The Following Year, And Twentytwo Days On The First Of The Third Year.
He made the lunar month consist of 291 days, the lunar year of 354, and the solar year of 365; days.