Suppose Mercury to be setting out from _A_ towards _B_ (between the Earth and left-hand corner of the Plate) and as seen from the Earth his motion will then be direct, or according to the order of the Signs. But when he comes to _B_, he appears to stand still in the 23d degree of ♏ at _F_, as shewn by the line _BF_. Whilst he goes from _B_ to _C_, the line _BF_ goes backward from _F_ to _E_, or contrary to the order of Signs; and when he is at _C_ he appears Stationary at _E_; having gone back 11-1/2 degrees. Now, suppose him Stationary on the first of _January_ at _C_, on the tenth thereof he will appear in the Heavens as at 20, near _F_; on the 20th he will be seen as at _G_; on the 31st at _H_; on the 10th of _February_ at _I_; on the 20th at _K_; and on the 28th at _L_; as the dotted lines shew, which are drawn through every tenth day’s motion in his looped path, and continued to the Ecliptic. On the 10th of _March_ he appears at _M_; on the 20th at _N_; and on the 31st at _O_. On the 10th of _April_ he appears Stationary at _P_; on the 20th he seems to have gone back again to _O_; and on the 30th he appears Stationary at _Q_ having gone back 11-1/2 degrees. Thus Mercury seems to go forward 4 Signs 11 Degrees, or 131 Degrees; and to go back only 11 or 12 Degrees, at a mean rate. From the 30th of _April_ to the 10th of _May_, he seems to move from _Q_ to _R_; and on the 20th he is seen at _S_, going forward in the same manner again, according to the order of letters; and backward when they go back; which, ’tis needless to explain any farther, as the reader can trace him out so easily through the rest of the year. The same appearances happen in Venus’s motion; but as she moves slower than Mercury, there are longer intervals of time between them. Having already § 120. given some account of the apparent diurnal motions of the Heavens as seen from the different Planets, we shall not trouble the reader any more with that subject. CHAP. VI. _The_ Ptolemean _System refuted. The Motions and Phases of Mercury and Venus explained._ 139. The _Tychonic System_ § 97, being sufficiently refuted by the 109th Article, we shall say nothing more about it.