io A Comprehensive View

the other side of the sun, its geocentric mo-tion is retrograde.

As Venus is moving from e to n, theappears in the line T n d D, and is seenamong the stars at D ; when the comes to f,her inferior conjunction, she appears amongstthe stars at C ; at m, she is seen in the con-cave sphere at B ; and when she is at a, inher own orbit, {he appears at A, in the hea-vens. Hence, as the planet passed throughe n f m a, in its natural motion, its apparentmotion was backwards, through E D C B A,or contrary to the order of the signs.

25, When the inferior planets are at theirgreatest elongation, they appear stationary,or continue in the fame place for sometime, before their motion changes fromdirect to retrograde, or from retrograde todirect again.

The time of the retrogression of Venusis about 40 days, of Mercury, 18 days.

26. In order to have a clear idea of theapparent motion of a planet, conceive thelines T a A, T b B, &c. to move with theearth ; so that the points e n f m a, whilstthe earth performs its revolution, may runthrough the orbit of the planet.

27. The