0°° 1

= 73 '

■ 0 ^

n O 1

10

io 8 Astronomy.

■

Venus in her. Orbit at A. And since the Orbit jt ,§is nearly circular, the Line T A will touch thethe Point A, and so the Angle T A S will be ® qVone. Suppose the Angle A T S = 47 Degreesservation ; then if we put the Distance os tp e ^ t |i«S T = 100000 , {■ay, As Radius or Sine of 9 0° lSSine of 47 0 , 1 ° is T S ~ ioocco to S A :nearly the Distance of Venus from the Sun.

12. In like manner may the Distance o ^from the Sun be determined in the Gross, bu ^ B finearly as that of Venus, because the Orbit is m uC ,j- jDexcentric or elliptical, and therefore the Angj_ e

will not be a Right one. Its Quantity therefo^.^^be found from the Theory of the Motions of * ^

founded on Observations ; and from thence o’®Angle T SR will be known, and consequentlyS R, which is the Distance of Mercury from the ^

13. In the Superior Planets this Matter is n °

so easy; however, there are divers Methods bfit may be done, by having the Theory of th eknown, which gives the Side S T ; and by Oh eT ]C C °the Angle S T P is known, which is the Dm^the Geocentric Place of the Sun and Planet; ^0'

remains only the Angle S P T to be found, whi c ^ vV ,j)ivHomers shew how to do several Ways; one 0 ^ o<bis peculiar to Jupiter , being done by means t <rof his Satellites, as will be shewn when ^’ sthem. _ . e

14. As I have in this Note mentioned tr> j c )ipnation of the Planets Orbits to the Plane of

tic, I shall give the Quantity thereof for each * yfollows: >

« 1 ?

' f Mercury is 6 $ 5

| Venus — 3 0

The Inclination of theOrbit of^ Mars — 1 1 n

\ ^vtoitar -— I ~ $

{^Saturn

cW.

Also the Line of the Nodes in the te ver ? etary Orbits is determined ; and the Place in 1 ^jlo^tic of the ascending .Node for each Planet is a® s