MONTH, originally the period of the moon's revolution round the earth. If this is reckoned from the position of the moon among the stars to her return to the same. posi tion, the period is called a sidereal month, and consists of 27 days, 7 hours, 43 minutes, 111 seconds; but if. from nvw _moon to.new moon, it is longer, being 29 days, 12 hours, 44 minutes, 3 seconds; this.isoalled a spiodie month (seeIroolN). Tliolatter period forms one of the three natural measures of the lapse of time, and, notwithstanding that its efficiency depends on the state of the atmosphere, it ranks next to the day in importance. There are several other periods toed by astronomers to which this name is applied, as the tropical or periodic M011 01 (27 days, 7 hours, 43 minutes, 4.7 seconds), reckoned from the moon's passing the equinox till her return to the same point; the nodal month (27 days, 6 hours, 5 minutes, 29 seconds), from ascending node to ascending node; the anomalistic month (27 days, 13 hours, 18 minutes, 37 seconds), from perigee to perigee; and the solar month, which is the twelfth part of a solar year, consisting of 30 days, 10 hours, 29 min utes, and 4 seconds. Distinct from all these is the civil or calendar month, fixed by law
for ordinary purposes, and consisting of a fixed number of days—from 28 to 31—accord ing to the particular mouth. The calendar mondis, with the number of days belonging to each, are as follow: 1. January ... 7. July.. 2, February 28 8. August.. . 31 " (leap years)......... 29 9. September 30 3. March 31 10. October 31 4. April 30 11. November . 30 5. :May. ............. ..... 31 12. December ail 6. June 30 See also the separate months under their own heads. The names by which the months .are designated throughout Christendom were given them by the Romans; and though Charlemagne in the 9th c., and the French directory in the end of last century, attempted to substitute descriptive epithets, the old-established names continue to be preferred.