of excess of a calendar month over a lunar month is the monthly epact. The epacts differ from
the Golden Numbers, from which they are derived, in that they provide for the adjustment of
(1) the solar equation, a correction of the Julian Calendar, and (2) the lunar equation, a
correction of the error in the lunar cycle. In its use in determining the date of Easter,
apparently more concern was paid to the consideration that it must not coincide with the
Passover than to astronomical exactness, for the Tables of Epacts are frequently in error by as
much as two days earlier or later.Ephemeral Map. One erected for the time of an event, to be judged by Horary Astrology.Ephemeral Motion. The day-to-day motion of the celestial bodies of the solar system in their
orbits. Said in contradistinction to directional or progressed motion.Ephemeris. pl. Ephemerides. An almanac listing the ephemeral or rapidly changing position
which each of the solar system bodies will occupy on each day of the year: their Longitude,
Latitude, Declination, and similar astronomical phenomena. The astronomer's Ephemeris lists
these positions in heliocentric terms; that of the astrologer, in geocentric terms. A set of
Ephemerides which includes the year of the native's birth, is essential in the erection of a
horoscope. Ephemerides were first devised by astrologers to facilitate the erection of a
horoscope. Finally, when they became of common use to navigators and astronomers, they were
given official recognition by the Government, and issued as the Nautical Almanac. The oldest
almanac in the British Museum bears the date 1431. It is said that Columbus navigated by the
aid of an Astrologer's Ephemeris.
Some of the notable ephemerides have been: Vincent Wing, 1658-81; John Gadbury, 1682-
1702; Edmund Weaver, 1740-46; Thomas White, 1762-1850 (also reappeared in 1883); George
Parker, in Celestial Atlas, 1780-90; John Partridge, in Merlinus Liberatus, 1851-59; E. W.
Williams, in the Celestial Messenger, 1858; W. J. Simmonite, 1801-61; Raphael, 1820 to date.
The old astronomical day which began at noon was abolished on Jan. 1, 1925, and since then
the astronomical day has begun at midnight. Gradually this is reflected in the making of
Ephemerides. Therefore it is important to verify whether the ephemeris one is using for any
given year since around 1930 shows the planets' places at noon or midnight. This can be
determined at a glance by noting the sidereal time on Jan. 1: if it is around 18h the ephemeris
is for noon; if around 6h, it is for midnight; if neither of these, it is probably calculated for
some longitude other than that of Greenwich.Epicycle. A term employed by Ptolemy, in whose astronomical system the Earth was regarded
as the centre, to indicate a small orbit around a central deferent (q.v.). He assumed that the orbits
of all the other planets formed epicycles around the Earth's orbit. It was involved in an attempted
solution of the phenomenon of retrograde motion. Assuming that the Sun pursues an orbit, the