DEFINITIONS.

a—A Calendar is a method of distributing time into certain periods adapted to the purposes of civil life, as hours, days, weeks, months, years, etc.

b—The only natural divisions of time are the solar day, the solar year, and the lunar month.

c—An hour is one of the subdivisions of the day into twenty-four equal parts.

d—The true solar day is the interval of time which elapses between two consecutive returns of the same terrestrial meridian to the Sun, the mean length of which is twenty-four hours.

e—The week is a period of seven days, having no reference whatever to the celestial motions, a circumstance to which it owes its unalterable uniformity.

f—The lunar month is the time which elapses between two consecutive new or full moons, and was used in the Roman calendar until the time of Julius CÆsar, and consists of 29d, 12h, 44m, 2.87s.

g—The calendar month is usually employed to denote an arbitrary number of days approaching a twelfth part of a year, and has now its place in the calendar of nearly all nations.

h—The year is either astronomical or civil. The solar astronomical year is the period of time in which the Earth performs a revolution in its orbit about the sun or passes from any point of the ecliptic to the same point again, and consists of 365 days, 5 hours, 48 minutes and 49.62 seconds of mean solar time. Appendix A.

i—The civil year is that which is employed in chronology, and varies among different nations, both in respect of the seasons at which it commences and of its subdivisions.