Page:The Burmese & Arakanese calendars (IA burmesearakanese00irwiiala).pdf/15



1. Of natural measures of time, denoted by revolutions and rotations of the heavenly bodies, the best-known and most important are the year, the lunation or synodic month, and the day. The principal artificial measures are the solar month (one-twelfth of a year}, the week, the hour, the minute, and the second.

2. For a description of the different measures of the year and month (tropical, sidereal and anomalistic years, synodic, sidereal, anomalistic, tropical and nodical months) the reader is referred to text books of astronomy. Such a description would be too lengthy to insert here.

3. The tropical year, lunation and day vary slightly in length, but none of them is ever an even multiple or sub-multiple of another. Therefore the problem of constructing a calendar to measure time by these three units is a very complex one. In Europe. Julius Cæsar simplified it enormously by abandoning the lunation altogether, and dividing the year into twelve artificial solar months without any remainder. This was not done in Asia, where lunations are still used.

4. Other methods of simplifying the problem are—

These methods have been adopted to varying extents at different times and in different parts of Asia, as will be seen later.