To find whether the year of our Lord be leap-year, or the first, second, or third after; divide it by four, and the remainder, if there be any, shews how many years it is after leap-year; but if there be no remainder, then that year is leap-year: Or, you may omit the hundreds and scores, and divide the residue by 4, _Examp._ 1757, omitting the hundreds and the twenties, I divide the residue 17, by 4, and the remainder 1, shews it to be the first after leap-year.
[Sidenote: _Julian Account_ or _the Old Style_.]
This method of reckoning the year, _viz._ making the common year to consist of 365 days, and every fourth year to have 366 days, is now used in _Great-Britain_ and _Ireland_, and some of the Northern parts of _Europe_, and is called the _Julian Account_, or the _Old Style_. But the time appointed by _Julius Cæsar_ for the length of a solar year is too much; for the Sun finishes his course in the ecliptic, in 365 days, 5 hours, and 49 minutes, which is 11 minutes less than the civil year; and therefore he again begins his circuit 11 minutes before the civil year is ended; and so much being gained every year, amounts in 131 years, to a whole day. So that if the Sun in any year entered the equinox upon the 20th of _March_ at noon, after the space of 131 years, he’ll enter the same point on the same hour, on the 19th of _March_. And therefore the exquinoxes will not always fall on the same day of the month, but by degrees will move towards the beginning of the year.
[Sidenote: _Gregorian Account_, or _New Style_.]
At the time of the _Council of Nice_, when the terms were settled for observing of _Easter_, the _Vernal Equinox_ fell upon the 21st of _March_; but by its falling backwards 11 minutes every year, it was found that in _Anno_ 1582, when the kalendar was corrected, the Sun entered the equinoctial circle on the 11th of _March_, having departed ten whole days from its former place in the year: and therefore Pope _Gregory_ the XIIIth, designing to place the equinoxes in their situation with respect to the year, took these ten days out of the kalendar, and ordered that the 11th of _March_ should be reckoned as the twenty-first: And to prevent the seasons of the year from going backwards for the future, he ordered every hundredth year, which in _Julian_ form was to be a _Bissextile_, should be a common year, and consist only of 365 days; but that being too much, every fourth hundred was to remain _Bissextile_. This form of reckoning being established by the authority of Pope _Gregory_ XIII. is called the _Gregorian Account_, or the _New Style_; and is observed in all the countries where the authority of the Pope is acknowledged, and likewise by several nations of the reformed religion. There being now above an hundred years past, since the reformation was made in the kalendar, the _Gregorian_ account has accordingly got before the _Julian_ one day more than it was in the time of its institution, the difference between these two accounts being now eleven days; so that the first day of any month, according to that way of reckoning, is the 12th of the same month, according to the New Style.