Numa added two months, _Januarius_ and _Februarius_. Numa's year consisted therefore of twelve months, according to the moon's course. But Numa's lunar year did not agree with the course of the sun, and he therefore introduced, every other year, an _intercalary_ month, between the 23d and 24th of February. The length of this month was decided by the priests, who lengthened or shortened the year, to suit their convenience. Cicero, in a letter to Atticus, x. 17, writes, in strong disfavor, of Numa's calendar. Julius Cæsar, with the aid of Sosigenes of Alexandria, adjusted this astronomical account. To bring matters into order, Suetonius, in his life of Julius Cæsar, 40, says, they were constrained to make one final year of fifteen months, to close the confusion. Hence arose the Julian or Solar year, the year of the Christian world. The "_alteration of the style_" is only an amendment of the Julian calendar, in one particular, by Pope Gregory, in 1582. In 325, A. D., the vernal equinox occurred March 21, and in 1582 it occurred March 10. He called the astronomers to council, and, by their advice, obliterated ten days from the current year, between October 4, and 15. These ten days make the difference, from 1582 to February 29, 1700. From March 1, 1700, to February 29, 1800, eleven days were required, and from March 1, 1800, to February 29, 1900, twelve days. In all Roman Catholic countries, this alteration of the style was instantly adopted; but not in Great Britain, till 1752. The Greeks and Russians have never adopted the Gregorian alteration of the style. The commencement of the year has been assigned to very different periods. In some of the Italian states, as recently as 1745, the year has been taken to commence, at the Annunciation, March 25. Writers of the sixth century have, occasionally, like the Romans, considered March 1 as New Year's day. Charles IX. by a special edict, in 1563, decreed, that the year should be considered to commence, on the first of January. In Germany, about the eleventh century, the year commenced at Christmas. Such was the practice, in modern Rome, and other Italian cities, as late as the fifteenth century. Gervais of Canterbury, who lived early in the thirteenth century, states, that all writers of his country considered Christmas the true beginning of the year. In Great Britain, from the twelfth century, till the alteration of the style in 1752, the Annunciation, or March 25, was commonly considered the first day of the year. After this, the year was taken to commence, on the first of January. The Chaldæan and Egyptian years commenced with the Autumnal equinox. The Japanese and the Chinese date their year from the new moon, nearest the Winter solstice.