or more barren; hence the characters and manners of nations
are changed; kingdoms and laws are altered, in accordance with the virtue
of the fixed stars as they culminate, and the strength thence received or
lost in accordance with the singular and specifick nature of each; or on
account of new configurations with the planets in other places of the
Zodiack; on account also of risings and settings, and of new concurrences
at the meridian. The Praecession of the aequinoxes arising from the
aequable motion of the Earth's pole in the arctick circle of the Zodiack is
here demonstrated. Let A B C D be the Ecliptick line; I E G the arctic
circle of the Zodiack. Then if the Earth's pole look to E, the aequinoxes
are at D, C. Let this be at the time of Metho, when the horns of Aries were
in the aequinoctial colure. Now if the Earth's pole have advanced to I;
then the aequinoxes will be at K, L; and the stars in the ecliptick C will
seem to have progressed, in the order of the signs, along the whole arc K
C: L will be moved on by the praecession, against the order of the signs,
along the arc D L. But this would occur in the contrary order, if the point
G were to face the poles of the earth, and the motion were from E to G: for
then the aequinoxes would be M N, and the fixed stars would anticipate the
same at C and D, counter to the order of the signs.

[Illustration]

* * * * *

{236} CHAP. IX.

On the anomaly of the Praecession of the Equinoxes,
_and of the obliquity of the Zodiack._

At one time the shifting of the aequinoxes is quicker, at another slower,
being not always equal: because the poles of the earth travel unequally in
the arctick and antarctick circle of the Zodiack; and decline on both sides
from the middle path: whence the obliquity of the Zodiack to the Aequator
seems to change. And as this has become known by means of long
observations, so also has it been perceived, that the true aequinoctial
points have been elongated from the mean aequinoctial points, on this side
and on that, by 70 minutes (when the prostaphaeresis is greatest): but that
the solstices either approach the equator unequally 12 minutes nearer, or
recede as far behind; so that the nearest approach is 23 degrees 28
minutes, and the greatest elongation 23 degrees 52 minutes. Astronomers
have given various explanations to account for this inequality of the
praecession and also of the obliquity of the tropicks.