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ASTRONOMY The ancient Grecian year. Days The Arabic and Turkifh year. Days N° Hecatombceon — - June- -July Muharram - - July. 16 Metagitnion — - July - -Aug. - Auguft 15 Saphar Boedromion — - Aug.- -Sept. - Septemb. 13 3 Rabia I. - Sept.- -Oa. Pyanepfion - Oftober 13 Rabia II. Maimadterion — - oa. - -Nov. Novemb. 11 Jornada I. - -- Decemb. - Nov.- -Dec. 11 Pofideon Jornada II. Gaineiion - Dec.- -Jan. January 9 Rajab — --February Anthefterion — -'Jan. - -Feb. 8 Shafban Elaphebolion — - Feb. - Mar. Ramadam - - March 9 - Mar.- -Apr. Munichion Shawal — - April 8 Thargelion - Apr.- -May 7 Dulhaadah - - May Schirrophorion - May- -June 5 Dulheggia - - June Days in the year Days in the year The Arabians add 11 days at the end of every, year, feafons. which keep the fame months to the fame A day is either natural or artificial. The natural day contains 24 hours ; the artificial the time from funrife to fun-fet. The natural day is either ajlrtnotnical or civil. The aftronomical day begins at noon, becaufe the increafe and decreafe of days terminated by the horE zon are very unequal among themfelves; which inequality is likewife augmented by the inconftancy of the horizontal refradtions, and therefore the aftronomer takes the meridian for the limit of diurnal revolutions, reckoning noon, that is, the inftant when the fun’s centre is on the meridian, for the beginning of the day.' The Britifli, French, Dutch, Germans, Spaniards, Portuguefe, and Egyptians, begin the civil day at midnight; the ancient Greeks, Jews, Bohemians, Silefians, with the modern Italians, and Ghinefe, begin it at fun-fetting; and the ancient Babylonians, Perfians, Syrians, with the modern Greeks, at fun-rifing. An hour is a certain determinate part of the day, and is either equal or unequal. An equal hour is the 24th part of a mean natural day, as *fhewn by well-regulated clocks and watches ; but thefe hours are not quite equal as meafured by the returns of the fun to the meridian, becaufe of the obliquity of the ecliptic and fun’s unequal motion in it. Unequal hours are thofe by which the artificial day “h divided into twelve parts, and the night into as many. An hour is divided into 60 equal parts called minuteti a minute into 60 equal parts called feconds, and thefe again into 60 equal parts called thirds. The Jews; Chaldeans, and Arabians, divide the hour into 1080 equal parts called ycra/’/cr; which number contains 18 times 60, fo that one minhte! contains 18 fcruples. A cycle is a perpetuaf rhund, or circulation of the fame parts of time of any fort. The cycle of the fun is a revolution of 28 years, inwhich time the days of the months return again to the fame days of the week; the fun’s place to the fame figns and degrees of the ediptic on the fame months and days, fo as not to differ one degree in 100 years; and the leap-years begin the
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fame courfe over again with refped to the days of the week on which the days of the months fall. The cycle of the moon, commonly called the golden, number, is a revolution of 19 years; in.which time, the conjundions,. oppofitions, and other afpe&s of the moon, are within an hour and half of being the fatpe as they were on the fame days of the months 19 years before. The indittion is a revolution of 15 years, ufed only by the Romans for indicating the times of certain payments made by the fubjeSs to the republic : It was eflablifhed by Conflantine, A. D. 312The year of our Saviour’s birth, according to the vulgar aera, was the 9th year of the folar cycle, the firfl year of the lunar cycle, and the 312th year after his birth was the firfl year of the Roman indidion. Therefore, to find the year, of the folar cycle, add 9 to any given year of Chrifl^ and divide the fum by 28, the quotient is the number of cycles- elapfed fince his birth, and the remainder is the cycle for the given year: If nothing remains, the cycle is 28 > To find the lunar cycle, , add 1 to the given-year of Chrift, and divide the fum by 19; the quotient is the. number of cycles elapfed in the interval, and the remainder is the cycle for the given year.: If nothing remains, the cycle is 19. Laftly, fubtradt 312 from the giyen year of Chrift, and divide the remainder by i 5 ; and what remains after this divifion is the indidlion for the given year : If nothing, remains, the indidtion is 15. Although the above defidency-in the lunar; circle of an hour and an half every 19 years be but fmall, yet in time it becomes fo. fenfible as to make a whole natural day in 310 years. So-that, although this cycle be of ufe, when the golden numbers are rightly placed againft the days of the months in the kalendar, as innur Common Prayer Books, for finding the days of the mean conjundtions or oppofitions of the fun and moon, and confequently the time of Eafter; it will only ferve for 310 years, old ftyle. For as the new and full moons anticipate a day in that time, the golden numbers ought
