## Month

Long before the exact length of the year was determined, it must have been perceived that the synodic revolution of the moon is accomplished in about 29&FRAC12; days. Twelve lunations, therefore, form a period of 354 days, which differs only by about 11&FRAC14; days from the solar year. From this circumstance has arisen the practice, perhaps universal, of dividing the year into twelve months. But in the course of a few years the accumulated difference between the solar year and twelve lunar months would become considerable, and have the effect of transporting the commencement of the year to a different season. The difficulties that arose in attempting to avoid this inconvenience induced some nations to abandon the moon altogether, and regulate their year by the course of the sun. The month, however, being a convenient period of time, has retained its place in the calendars of all nations; but, instead of denoting a synodic revolution of the moon, it is usually employed to denote an arbitrary number of days approaching to the twelfth part of a solar year.

Among the ancient Egyptians the month consisted of thirty days invariably; and in order to complete the year, five days were added at the end, called supplementary days. They made use of no intercalation, and by losing a fourth of a day every year, the commencement of the year went back one day in every period of four years, and consequently made a revolution of the seasons in 1461 years. Hence 1461 Egyptian years are equal to 1460 Julian years of 365&FRAC14; days each. This year is called vague, by reason of its commencing sometimes at one season of the year, and sometimes at another.

The Greeks divided the month into three decades, or periods of ten days, - a practice which was imitated by the French in their unsuccessful attempt to introduce a new calendar at the period of the Revolution. This division offers two advantages: the first is, that the period is an exact measure of the month of thirty days; and the second is, that the number of the day of the decade is connected with and suggests the number of the day of the month. For example, the 5th of the decade must necessarily be the 5th, the 15th, or the 25th of the month; so that when the day of the decade is known, that of the month can scarcely be mistaken. In reckoning by weeks, it is necessary to keep in mind the day of the week on which each month begins.

The Romans employed a division of the month and a method of reckoning the days which appear not a little extraordinary, and must, in practice, have been exceedingly inconvenient. As frequent allusion is made by classical writers to this embarrassing method of computation, which is carefully retained in the ecclesiastical calendar, we here give a table showing the correspondence of the Roman months with those of modern Europe.

Instead of distinguishing the days by the ordinal numbers first, second, third, etc., the Romans counted backwards from three fixed epochs, namely, the Calends, the Nones and the Ides. The Calends (or Kalends) were invariably the first day of the month, and were so denominated because it had been an ancient custom of the pontiffs to call the people together on that day, to apprize them of the festivals, or days that were to be kept sacred during the month. The Ides (from an obsolete verb iduare, to divide) were at the middle of the month, either the 13th or the 15th day; and the Nones were the ninth day before the Ides, counting inclusively. From these three terms the days received their denomination in the following manner: - Those which were comprised between the Calends and the Nones were called the days before the Nones; those between the Nones and the Ides were called the days before the Ides; and, lastly, all the days after the Ides to the end of the month were called the days before the Calends of the succeeding month.

In the months of March, May, July and October, the Ides fell on the 15th day, and the Nones consequently on the 7th; so that each of these months had six days named from the Nones. In all the other months the Ides were on the 13th and the Nones on the 5th; consequently there were only four days named from the Nones. Every month had eight days named from the Ides. The number of days receiving their denomination from the Calends depended on the number of days in the month and the day on which the Ides fell. For example, if the month contained 31 days and the Ides fell on the 13th, as was the case in January, August and December, there would remain 18 days after the Ides, which, added to the first of the following month, made 19 days of Calends. In January, therefore, the 14th day of the month was called the nineteenth before the Calends of February (counting inclusively), the 15th was the 18th before the Calends and so on to the 30th, which was called the third before the Calend (tertio Calendas), the last being the second of the Calends, or the day before the Calends (pridie Calendas).

 Days oftheMonth. March.May.July.October. January.August.December. April.June.September.November. February. 1 Calendae. Calendae. Calendae. Calendae. 2 6 4 4 4 3 5 3 3 3 4 4 Prid. Nonas. Prid. Nonas. Prid. Nonas. 5 3 Nonae. Nonae. Nonae. 6 Prid. Nonas. 8 8 8 7 Nonae. 7 7 7 8 8 6 6 6 9 7 5 5 5 10 6 4 4 4 11 5 3 3 3 12 4 Prid. Idus. Prid. Idus. Prid. Idus. 13 3 Idus. Idus. Idus. 14 Prid. Idus. 19 18 16 15 Idus. 18 17 15 16 17 17 16 14 17 16 16 15 13 18 15 15 14 12 19 14 14 13 11 20 13 13 12 10 21 12 12 11 9 22 11 11 10 8 23 10 10 9 7 24 9 9 8 6 25 8 8 7 5 26 7 7 6 4 27 6 6 5 3 28 5 5 4 Prid. Calen. 29 4 4 3 Mart. 30 3 3 Prid. Calen. 31 Prid. Calen. Prid. Calen.