L 407 1 
the pole P\ with refped to the line S C and the 
direction of the oppofite pole p, goes on the fame 
fide as the diredion of the point E of the equator 
which is placed on the fame fide of the pole P with 
refped to the line S C D . This fhould be carefully 
attended to in regard to the following Problem, . 
Problem V. 
11. Eo determine at every injlant the motion of the 
; pole of the earth with reJpeSl to the ecliptic. 
P P', fig . 2. 7 z° i. & n 2*. is the earth’s axe, 
T $ vj> r eprefents the ecliptic ; s E' p E s is the 
tangent plane to the pole P, and parallel to the equa- 
tor j the line JD s D z is the interfedion of this plane 
with that of the ecliptic, and is tangential at the com- 
mon point s to the circles & E p E s> and T s * 
The angle PC s is the angle of inclination of the 
earth’s axe to the plane of the ecliptic, being like- 
wife the folfticial angle. The earth, by its diurnal 
motion, turns about the axe P' P according to the 
order of s s £' /> £ s ; and the fun, by the annual 
motion in the ecliptic, moves according to the order 
of T $ - Vf. 
Let S be any place of the fun in the ecliptic. By 
Art. 10. the motion of the pole P making the acute 
angle P C S , will be according to P p perpendicular 
to the plane P C S D P, and confequently to the line 
P D. 
* Note , That the fig. «° 2. is only to reprefent the circle 
S E p S, which could not be reprefented but by projection in 
fig. n° !• 
