SIGNS BEHOLDING EACH OTHER, AND OF EQUAL POWER
Any two signs, equally distant from either tropical sign, are equal to
each other in power; because the Sun, when present in one, makes day
and night, and the divisions of time, respectively equal in duration
to those which he produces when present in the other. Such signs are
also said to behold each other, as well for the foregoing reasons, as
because each of them rises from one and the same part of the horizon,
and sets in one and the same part.[46]
[46] Whalley has a very lengthy note upon this and the preceding
chapter, to show that Ptolemy here speaks of zodiacal parallels, or
parallels of declination, and to point out the necessity of observing
a planet’s latitude, in order to ascertain its true parallels. It is,
however, to be recollected, that the parallels now alluded to are
distinct from the _mundane parallels_, which are equal distances from
the horizon or meridian, and are considered by Ptolemy in the 14th and
15th Chapters of the 3rd Book of this work; although not under the
express name of mundane parallels.