then he found that s' m was equal to the former s m, but that ♈︎ m' was greater than the former ♈︎ m, or that m'
was slightly to the east of m. This change m m' being nearly the same for all stars, it was simpler to attribute it
Fig. 23.—The precession of the equinoxes.
to an equal motion in the opposite direction of the point ♈︎, say from ♈︎ to ♈︎' (fig. 22), i.e. by a motion of the equator from ♈︎ n to ♈︎' n', its inclination n' ♈︎' m remaining equal to its former amount n ♈︎ m. The general effect of this change is shewn in a different way in fig. 23, where ♈︎ ♈︎' ♎︎ ♎︎' being the ecliptic, a b c d represents the equator as it appeared in the time of Timocharis, a' b' c' d' (printed in red) the same in the time of Hipparchus, ♈︎, ♎︎ being the earlier positions of the two equinoctial points, and ♈︎', ♎︎' the later positions.
