482

Third Operation —Conversion of the Right Ascension in

into Space.

By Zach’s Tables, Tab. XXIX, or Vince’s, vol. II. P- 29? ’

6 h .S' 0° O' 0"

39 . 0 9 45 0

39 . 0 0 9 45

3 . 0 0 Q 4.5

3 9 54 49.5 Sun’s right ascension in space.

The obliquity was 23° 28' 4 ", from that and the right asC ^ S J^ sfind the Sun’s longitude by Naper’s Rule, or thus, by the iof Reduction to the ecliptic.

Fourth Operation —Reduction of Equator to the Ecliptic

See Zach’s Table XXI, in his Tabula, Motuum SoU s >Vince’s Table, Astronomy, vol. II, p. 352.

Add 3".

Reduction.

6 s 9° 50' 0".0.0‘ 0° 47' 57".45

0 0 4 49.5 . 0 0 0 22.69

(obliquity being 23° 28') 0 0 48 20.14

add for 4". 0 0 0 0.27

0 0 48 20.41

Difference for V.

4". 7034

18.812 for 4' 0"-°3.88 0 49- 5

2 2.69 '4 49-5

Sun’s right ascension. . 3 9 54 49.5

Sun’s longitude. 3 9 6 29.1

f

and this is the whole of the process for the actual finding ° rSun’s longitude from his observed right ascension.

By a similar process performed on Maskelyne’s observati°°of the Sun’s transit on the December 31, we haveG’s longitude = 9 8 10° 3l' 7".6.

Fifth Operation —Difference of Sun’s Longitude found.The above are the Sun’s longitudes when his centre wa s otl

* See Chapter XXI.