CHRONOLOGY. 



cal return of certain appearances, sea- 

 sons, &c. would in due course lead to the 

 adoption of this larger division. At 

 what time this took place is uncertain, 

 but probably not before considerable ad- 

 vances had been made in astronomical 

 science. It was long 1 , however, after its 

 first adoption, before it attained to any 

 thing like an accurate form. The 

 most ancient measure of the year, of 

 which we know, consisted of twelve lu- 

 nar months, which, for the facility of 

 computation, being all considered as 

 equal in length, and to contain thirty days 

 each, amounted to 360 days. It is conjec- 

 tured that this gave rise to the division of 

 the ecliptic, which still obtains, into 360 

 equal parts or degrees. 



This luni-solar year probably had its 

 rise in Chaldaea, or Egypt ; we learn, at 

 least, from the testimony of Herodotus, 

 that it was used in the latter country. 

 Hence, with the diffusion of science, it was 

 carried into other regions, and very gene- 

 rally adopted. It was early in use among 

 the Indians, Chinese, the Medes, and Per- 

 sians, and the ancient Greeks. Its measure 

 being, however, inaccurate, containing 

 five days and a quarter more than the lu- 

 nar, and as much less than the true solar 

 year, and this defect becoming every year 

 more perceptible from the retrocession 

 of the seasons, &c. it was soon consider- 

 ed necessary to subject it to some revi- 

 sion. The Thebans are supposed to have 

 been the first who undertook its correc- 

 tion, by making an annual addition of 

 five days to the luni-solar year. Thales 

 introduced this improvement into the an- 

 cient Grecian year, and it was adopted, 

 with some trifling variations in particular 

 instances, into the Indian, the Chinese, 

 and the Jewish year. 



The Roman year, as regulated by Ro- 

 mulus, and afterwards reformed by his 

 successor Numa, was reckoned by lunar 

 months, and adjusted to the seasons by 

 a number of intercalary days. It consist- 

 ed often lunar months, of which Decem- 

 ber was the last, and to these two whole 

 intercalary months were added, but not 

 inserted in the calendar. This year be- 

 gan at first in March ; but the Decemviri, 

 \vho undertook its reformation, changed 

 the order of the months into that in which 

 they now stand, introduced the two in- 

 tercalary months, January and February, 

 into the calendar, and made January the 

 first month of the year. 



Owing to the ignorance, or the care- 

 lessness, of the Pontifices Maximi, to 

 whose care the regulation of the interca- 



lary days was committed, the year was 

 reduced to such disorder in the time of 

 Julius Caesar, that the winter months had 

 fallen back to the autumn. To restore 

 them to their proper season, Caesar 

 formed a year of 445 days, which has 

 been styled the year of confusion. With 

 the assistance of Sosigenes, a mathemati- 

 cian of Alexandria, he afterwards, in the 

 year B. C. 45, instituted a solar year of 

 365 days 6 hours, which is now known 

 under the name of the Julian year. To 

 adjust this year to the annual revolution 

 of the earth, which is six hours and 

 some minutes more than 365 days, the 

 length of the ordinary year, a day was 

 appointed to be intercalated every fourth, 

 year in the month of February : this day, 

 from its position in the Roman calendar, 

 was called bissextile, a name which has 

 also been given to the year in which the 

 intercalation takes place. 



The Julian year, although it approach- 

 es very near the truth, is not, however, 

 perfectly correct. The true time of the 

 annual revolution of the sun in the eclip- 

 tic is 365 days, 5 hours, and nearly 49 

 minutes, which falls short by a few mi- 

 nutes of the time assumed in the Julian 

 year. How trifling soever this difference 

 might at first appear, it amounted in a 

 hundred and thirty-one years to a whole 

 day : in consequence of this, the vernal 

 equinox, which Sosigenes, in the first 

 year of the Julian correction, observed to 

 fall on the 25th of March, had gone back 

 in A. D. 325, at the time of the council 

 of Nice, to the 21st, and in A. D. 1582, 

 to the llth of March. To remedy this 

 growing defect, Pope Gregory XIII. 

 caused the calendar to undergo another 

 correction. In A. D. 1580, he ordered 

 ten days to be cut out of the month of 

 October, so that the fourth was reckoned 

 the 15th day : and to prevent such retro- 

 cession in future, in addition to the Ju- 

 lian regulation with respect to the bissex- 

 tile year, he ordained that the years 

 1600", 2000, 2400, and every fourth c'entu- 

 tury in succession, should have an inter- 

 calation of a day, but that in the other 

 centuries, 1700, 1800, 1900, 2100, &c. 

 the day should be omitted, and those 

 years remain common years. This re- 

 gulation comes so near the truth, that the 

 only correction it will require will be 

 the suppression of a day and a half in five 

 thousand years. 



The Gregorian year, or, as it is vulgar- 

 ly called, the new style, was immediately 

 adopted in Spain, Portugal, and part of 

 Italy. It was introduced into France in 



