ÆRA, in Matters of Chronology, signifies the same with Epoch; that is, any Point of Time, determined at Pleasure, whence to begin the Computation of the Years elapsed since. See EPOCH.
The generality of Writers agree, that the Era was originally used in respect of the system of reckoning Time among the Spaniards; whose Era was thirty-eight Years older than the Christian Epoch, or Year of Grace. Peter the fourth King of Aragon, was the first who abolished the Spanish Era in his States, in the Year 1350; as did John I, King of Portugal, in 1415. The Origin of the Word is somewhat obscure. Feuvrier says, that in Cicero and Lucilius, the Word Era is plural, and signifies the same thing with Commentaria, Leaves of a Book of Accounts, or a Merchant's Journal.
Others, according to the same Author, are of opinion that Era was used instead of Hera, for Herus, Master, Lord; and that it signified the Dominions of a Prince. Others, according to him, believe the Word derives from Argentum, Silver, on account of the Tax of a Piece of Silver, imposed by Augustus on the Heads of all the Subjects of his Empire. Others say, that the Word is formed from the initial Letters of the three first Words in the public Acts, Actus Erae Augusti; but these three last Etymologies are rejected with good Reason.
