a fixed point of time, commonly selected on account of some remarkable event by which it has been distinguished, and which is made the beginning or determining point of a particular year from which all other years, whether preceding or ensuing, are computed. The creation and the birth of Christ are the most important of the historical epochs. The creation has formed the foundation of various chronologies, the chief of which are 1, The epoch adopted by Bossuet, Ussher and other Catholic and Protestant divines, which places the creation in 4004 B. C.; 2, The Era of Constantinople (adopted by Russia), which places the creation at 5508 B. C.; 3, The Era of Antioch used till 284 A. D., placed the creation at 5502 B C.; 4, The Era of Alexandria placed it at 5492 B. C. This is also the Abyssinian Era; 5, The Jewish Era, which places the creation in 3760 B. C. The Greeks computed their time by periods of four years, called Olympiads, from the occurrence every fourth year of the Olympic games. The first Olympiad, being the year in which Coroebus was victor in the Olympic games, was in the year 776 B. C. The Romans dated from the supposed era of the foundation of their city, April 21 in the third year of the sixth Olympiad, or 753 B. C. The Christian Era, or mode of computing from the birth of Christ as a starting-point, was first introduced in the sixth century and was generally adopted by the year 1000. This event is believed to have taken place earlier, perhaps by four years, than the accepted date. The Julian epoch, based on the coincidence of the solar, lunar and indictional periods, is fixed at 4713 B. C. and is the only epoch established on an astronomical basis. The Mohammedan Era, or Hegira, begins on July 16, 622, and the years are computed by lunar months. The Chinese reckon their time by cycles of 60 years.