Note 78 — CHAP. XIX. The Calculation of New and Full Moons and Eclipses. The geometrical Construction of Solar and Lunar Eclipses. The examination of antient Eclipses.

When the Romans divided the Empire, which was about 38 years before Christ, Spain fell to Augustus’s share: in memory of which, the Spaniards dated all their memorable events ab exordio Regni Augusti; as Christians do from the birth of our Saviour. But in process of time, only the initial letters AERA of these words were used instead of the words themselves. And thus, according to some, came the word ÆRA, which is made use of to signify a point of time from whence historians begin to reckon.