564

To find the longitude,

A .81° 23' 16 "

I .23 27 54

s,

87 1

2 sum .... 96

2 ) 192 5 105

.log. sin. 9-995075-

.log. sin. 9.60008$

Ij? .. * .. (d) 19-5951643

j sum — h

4

8 47

.log. sin. 9.99755$

5 . . . ...log. sin. 9*'^$^

2 log. r 20 _

S9.18146 23(d) 1$5951^3■ ! . 2 ) 19 . 586298 ®

9 793149°

Now 9.7931490 is the log. sin. of 38° 23' 40", &c. aH ^360° + 38° 23' 40" = 398° 23' 40"

.*. 90 + L = 796 47 20X = 706 47 20

= 360° + 346" 47' W"'

rejecting 360°,

the geocentric longitude of S , or L = 1 I s 16° 47 20 •

By these means, then, that is, by meridional observation*the planet, and by computations, may its longitude and l a | ltu ^be determined. Amongst the resulting values of the l® 111 ^there must be some either nothing or very small. Nowgeocentric latitude is nothing, the heliocentric also is 110 jor the planet is in the plane of the Earth ’s orbit: or, technio ^the planet is in its node : the node being the intersection 0orbit of a planet, with the plane of the ecliptic. We are o(f jcthen, by examining the series of the values of the g e ° ce . s j nlatitudes, (computed as above) to determine when a plan etits node, and we also know the geocentric longitude coiresp 00to such a situation of the planet.