สำนักราชบัณฑิตยสภา

The Journal of the Royal Institute of Thailand Vol. 27 No. 3 Jul.-Sept. 2002 ‡«≈“¡“µ√∞“π‰∑¬ ˜ˆÚ Abstract The Thai Standard Time Visudh Busyakul Associate Member, the Academy of Arts, the Royal Institute, Thailand The confusion in time reckoning due to the concurrent use of several independent railroad times and local times in America led to the international conference of 27 nations in 1884 in Wash- ington D.C., which eventually resulted in the international agreement of establishing time zones around the world. The ancient Babylonian and Egyptian thinkers attempted to create a calendar sysatem based on the movements of celestial bodies known to them at that time, but it was Julius Caesar who first announced the Julian calendar in 46 BC. This calendar, which was suggested by Sosigenes of Alex- andria, was in 1582 A.D. improved upon by Pope Gregory XIII. The basic calendar system of the Thai people is lunar, but the refinement, especially the adjust- ment of year length, is based on Suriyayatra, an old astronomical text reportedly imported from the Mon nation in southern Burma. The Buddhist era, the Mahasakkarat era, and the Chullasakkarat era were all employed in the Ayutthaya period. In B.E. 2432 (A.D. 1889) King Rama V founded the Ratanakosin Era and introduced the solar calendar system as the official time reckoning. The era was in use for 23 years. In B.E. 2455, King Rama VI reverted to the Buddhist Era, but the actual solar calendar system was kept unaltered. According to the ancient Thai general practice, a new day began at sunrise, and was from B.E. 2460 (A.D. 1917) changed to midnight to conform to the international practice. The official “Bangkok mean time” was a few years later changed from that based on the longitude of Bangkok to be exactly seven hours ahead of GMT. The New Year‘s day of the Buddhist era was changed to January 1 in A.D. 1941. The traditional New Year’s Day, which historically coincided with the vernal equinox of modern astronomy, has been kept as a traditional public holiday. The fixing of the day is governed by the traditional Suriyayatra text, which causes it to be moved fromMarch 21st to April 16th at the present time. The day will continue to move and will fall on April 24th in 500 years from now. Key word : Thai standard time