Again, the annual regular, or the regular cited in charters (as in our previous quotation, where it is called the paschal regular), is neither the solar regular described in the former part of this article, nor the lunar regular just mentioned, but a third regular belonging to the whole year, and which, added to the concurrent previously described, gave (7 being abated, if necessary) the last day of the moon preceding the paschal moon. Thus, A.D. 874, the concurrent being 4 and the annual regular 5, their sum 9 diminished by 7, or 2, gives Jloudny as the last day of the ante-paschal moon.
The panchal term (terminus paschalis) mentioned in the quotation, meant simply the fourteenth day of the paschal moon.
3. The Indiction was an edict of the Homan emperors, fixing the tribute ; and as one such edict was supposed to have appeared every fifteen years, years were naturally reckoned according to their distance from the year of indiction. There is doubt about the first origin of indictions, about their meaning and their earliest date : all we have here to do with is the fact, that from Athanasius downwards, they were more or leas employed by ecclesiastical writers in describing epochs. The popes afterwards adopted this mode of dating, and the common indiction • found in chronological tables begins so that A.D. 313 is the first year of the first cycle of indiction, each cycle containing 15 years. At this rate, ear. 1 was the fourth year of an imaginary pre. ceding indiction, and the remainder of three more than the date of any Year divided by 15 will give its position in its cycle of indiction. Thus 1'239, increased by 3 and divided by 15, gives the remainder 12, or A.D. 1239 is the twelfth year of a cycle of indiction.
4. The paschal cycle is one composed of 28 and 19 years, or 532 years, during which time the cycles of the sun and of 19 years run through all their combinations, and recommence them again. Accord ing to the old system, then, this is the cycle of Easter Days, which begin again in the same order when it is finished: A.D. 1 was the second year of the first paschal cycle, being also 2 of the cycle of 19 years, and 10 of its solar cycle. The paschal cycle of the Oregoriau calendar would be 53,200 years.
5. The Julian t period was imagined by Joseph Stanger, and is a combinations of the solar cycle, the cycle of 19 years, and that of indictions. Now 28 x 19 15 gives 7980 years, which is the length of the period in question. It was made to begin at a year lac., which was the first year of each cycle—namely, rte. 4713 years. Hence, sub tract any year rte. from 4714, or add any year A.D. to 4713, and you have the year of the Julian period answering to the date used. The advantage (if it be one) of this period is, that by dividing the year in it by 28, 19, and 15, the remainders show the years of the different cycles belonging to the Julian date used, remembering when the remainder is nothing to substitute the divisor instead.
For the history of periods not absolutely used in chronology, see their several names, such as Metouic Cycle, underArrosr, in lhoo. Div., SAII0S, SOTHIAC PERIOD, &C., fie.
Astronomical periods, actually existing in nature, may be divided into days, connected with the rotations of planets round their axes; months, connected with the rotation of satellites round their primaries; years, connected with the rotations of primary planets round the sun ; and secular periods, connected with slow changes of the elements of orbits. • The most convenient period of measurement is the civil or mean solar day at the earth, being the average interval between noon and noon. [Svsonmc REVOLUTION.] This period being divided into hours. &c., the actual rotation of the earth is 23h 56. 4..09, and is called the sidereal day. The average interval between two transits of the moon over the meridian is 24% 50. which might be called the mean tide-day. The rotation of the moon is the time of her revolution round the earth [MOON]; and the rotations of the planets are as follows (in sidereal time) so as to mnke 24` the rotation of the earth:— Various months are described in the article MOON, the only ones hero necessary to cite being the one already used, of 29° 44. 2-9, or the average interval front new moon to new moon, and 27d 7h 43m 11'5, or the actual time of revolution of the moon in the heavens. The satellites of Jupiter, Saturn, and Uranus have revolutions round their primaries as follows :— The following are the old statements relative to the satellites of Uranus, as given by William Herschel Such an article as this is not the place to enter upon the doubts relative to these bodies.
The civil year is the tropical year, or the time of revolution of the sun from the vernal equinox to the same again. Owing to the motion of the equinox [PRECESSION], this year, or 365' 5° 4Sr° 49"7, or is shorter than the actual revolution of the earth round the sun, which is 365d 9°' 9''6, or Again, the anoma listic year, being that in which the earth moves from its nearest point to the sun to the same again, is 365d 6° 13° 49"3, or The following is the list of the actual revolutions of the planets round the sun, each to a tenth of a day, including the verified periodic comets, so far as their times are known :— Of secular periods, the most important are, the revolution of the moon's node, in 18'6 years ; of the earth's perihelion, from the vernal equinox to the vernal equinox again (the latter also moving), or 21,000 years, and the revolution of the equinoxes themselves, in 26,000 years.