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ftands against Sunday, or the Lord's-day, in Latin Dies Dominica, is called the Dominical Letter, and ferves to denote that day, as the other letters do the other days of the week.

The Dominical Letter is different every year. As the common year confifts of 365 days, that is, fiftytwo weeks, and one day, it is evident the year must begin and end on the fame day of the week, and therefore the next year will begin on the day following. This occafions the first Sunday in January, to fall every year a day fooner than it did the year before, and confequently to be denoted by a different letter.

In biffextile or leap-year, consisting of 366 days, there are fifty-two weeks, and two days over; fo that if the leap-year begins on a Sunday, it will end on a Monday, and the next year begin on a Tuefday, and confequently the Dominical Letter will be removed two places backwards; that is, if it be A at the beginning of the leap-year, it will be F the year following. By this means, every fourth year being biffextile, the order of the Dominical Letters is interrupted, and the feries does not return to its first state till aner four times seven, or twenty-eight years. This period of time is the cycle of which we are now difcourfing.

The

The Dominical Letters are not the fame in the Gregorian, as in the Julian calendar. By the reformation of the calendar under Pope Gregory, the order of the Dominical Letters was difturbed; for the year 1582, which at the beginning had G for its Dominical Letter, came to have C in October, by the retrenchment of ten days after the 4th of that month. And thus the Dominical Letter of the ancient Julian calendar is four places before that of the Gregorian, the letter A in the former anfwering to D in the latter.

In order to find the year of the folar cycle for any year of Chrift, proceed thus: Add 9 to the given year, and divide the fum by 28; the remainder will shew the year of the cycle, and the quotient the number of cycles fince the birth of Chrift. If there be no remainder, the given year is the 28th or last year of the cycle. The reason of the addition of 9 is, because the ninth year of the folar cycle was paft, when the first year of the Chriftian computation began.

The cycle of indiction is a circle or revolution of fifteen years, which when expired begins anew, and goes round again without intermiffion. This cycle has no relation to the celeftial motions, but was made ufe of by the Romans to make known the time of paying certain taxes, or for other civil purposes.

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purposes. The popes have dated their bulls by the year of the indiction ever fince the time of Charlemagne.

"The commencement of this cycle being fixed to the 3d year before Chrift, add 3 to the given year, divide the fum by 15, and the remainder will fhew the year of indiction for any given year of Chrift. If nothing remains, it is the 15th or laft the cycle.

year of

CHA P. LIX. iv.

OF THE GOLDEN NUMBER, AND THE EPACTS.

་ ་

"THE prime or golden number is a revolution of mineteen years, and is that particular number which fhews the year of the lunar cycle for any given year. So that to find the year of the funar cycle is to find the golden number. Thefe numbers are called golden, becaufe, being of excellent ufe, they were expreffed in ancient calendars by figures of gold.

In the first year of our Saviour's nativity, the golden number was 2.; therefore add 1 to any given year of Christ, divide the fum by 19, and the re

mainder.

mainder is the golden number for that year. If nothing remains then 19 is the golden number. Thus, for inftance, divide. 1801 by 19, the remainder will be 15, the golden number for 1800.

This number is ufed in the calendar to fhew the changes of the moon, and thereby to determine. the time of Eafter, and other moveable feasts.

Epacts are, as the word implies, added numbers; that is, a number of days added to the lunar year, to make it equal to the folar year. The folar year has 365 days, and almost 6 hours; and the lunar year 354 days, and upwards of 8 hours. The dif ference is, the epact. Now as this difference is not much short of 11 days, it was made the epact of the first year of the lunar cycle..

To find the epact; multiply the golden number by II, from that product fubtract 11, divide the remainder by go, and the remainder of the divifion is the epact. For example; I would know the epact for the year 1800, of which the golden number is 15. This multiplied by 11 produces 165, from which I being fubtracted, there remains 154 and this when divided by 30, has a remainder of 4, the epact required. ***

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If after the operation nothing remains, then 30 is the epact!

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СНА РА

CHAP. LX.

HOW TO FIND THE MOON'S AGE, AND THE DOMINICAL LETTER,

Norder to find the moon's age, add to the epact for March o in common years, and, in leapyears, for April 2, for May 3, for June 4, for July 5, for Auguft 6, for September 8, for October 8, for November 10, for December 10, for January o, for February 2.

Having added to the epact the number for the month, according to the foregoing rule, add thereto the day of the month for which the moon's age is required. The sum of these three, if less than 30, is the moon's age; if more than 30, take 30 from it, and the remainder is the age of the moon.

The moon's age, fubtracted from the day of the change, leaves the day of full moon. When nothing remains, that day of the month is the day of change.

How old is the moon on the 20th of May 1800? In order to refolve this question, add to the epact, already found to be 4, the number for May, which is 3, and 20, the day mentioned in the question, the fum will be 27 days, the answer required.

To

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