170

Astronomy.

1 $

Lengths of Days and Nights, the ^.^sof Solar and Lunar Eclipses, thePhases of the Moon,. &c. jrl

0 f$

Inclination of the Axis of the Earth to theEcliptic, viz. the Angle PC H, which is f° ul1 Qoservation to be about 66° 30", and therefor® ^ splemental Arc E P or the Angle P C E

16. Through the PoleP from the Point E HSlesser Circle P F G, which will be parallel _ j a £ 3 Jclip tic ; then if the Axis of the Earth be dire ' ^ ^ jparticular Time to P, it is found by Obstt $£<} ^

many Years, that it will not constantly be rS t^j,the Point P in the Heavens, but will in 7 2 t he ^■ijbe directed so some other Point Q_, so that so .

P Q_= 1 Degree; and therefore in the Spa®®

72 — 25920 Years, the Point P or Pole of ^ 0 f *will describe the Circle PFG about the 1° { rUEcliptic E, which Revolution is call’d the pd

17. The Cause of this Conical Motion of *■ ^ fl>‘ ^Axis was unknown to all the Astronomers ^ 0 f Atsophers before Sir Isaac Newton's Time, n °^ £e d pbeing able to guess from whence it could pre ^ i¥.,this divine Geometer soon investigated the J-'of, and demonstrated it to result from theE a , fisiftion and Gravity, that is, from the Spheroid ^5 n ,the Earths for were the Earth a perfect G!e ’ e p0‘would always remain Parallel to itself, and n a ^Motion. See the Erin dpi a. . folios J

18. From this Motion of the Earth’s A* 1 ® ^veral remarkable Phœnomena ; as First-, a £0 % t3 ccf the Pole-Star ; for ’tis evident, if any itchance to coincide with the Pole P at any * l ^ jafter 72 Years be left at the Distance QJ ’ th 6flgree Westward, and the Star at Q_becoin .

North Pole-Star. m in Lf,

,19. Secondly, The present Polar Star thAidbe on the South Part of our Meridian ; that 1 1 v. ^which suppose at present at P, will after 1 ^ s ch ° t sbe at G, which being 47 Degrees (in th® K