ON SOLAE PHYSICS. 
11 
the centre =g. 
We have from the figure 
r 0'S'_0'S' 
E O'B O' S 
=sin O' S S' = sin (f +f'), 
or 
f+f-sin" 1 ^ 
hence 
g = sin 1 
/ . 
E-f- 
(2) 
To facilitate the application of this correction the following Table has been calculated, 
which gives the logarithm of (R) for every tenth day of the year. 
Values of log(R). 
Jan. 1. 
1-212 
| Mar. 22. 
1-206 
June 10. 
1-198 
Aug. 29. 
1-201 
Nov. 17- 
1-210 
11. 
1-212 
Apr. 1. 
1-205 
20. 
1-198 
Sept. 8. 
1-202 
27. 
1-211 
81. 
1-212 
11. 
1-204 
30. 
1-198 
18. 
1-203 
Dec. 7- 
1-212 I 
31. 
1-211 
21. 
1-203 
July 10. 
1-198 
28. 
1-204 
17. 
1-212 
Feb. 10. 
1-211 
May 1. 
1-201 
20. 
1-198 
Oct. 8. 
1-206 
27. 
1-212 ! 
20. 
1-210 
11. 
1-200 
30. 
1-199 
18. 
1-207 
Mar. 2. 
1-209 
21. 
1-199 
Aug. 9. 
1-199 
28. 
1-208 
12. 
1-207 
31. 
1-199 
19- 
1-200 
Nov. 7. 
1-209 
11. Next, let C'EC (fig. 7) represent the ecliptic, Q'EQ the 
celestial equator, and P, P' the poles of these circles. Then if S is 
the position of the sun, E S will be its longitude = ©, and the angle 
SEM=w, the inclination of the ecliptic. 
Now, if the angle P S P' = G represents the inclination of two planes 
passing through the line joining the centres of the sun and earth, 
and the poles of the earth and ecliptic respectively, then in the tri- 
angle E S M, right-angled at M, we shall have 
Pig. 
cos E S=cot SEM cot E S M, 
or 
whence 
cos O =cot ro tan G, 
tan G=tan ts cos © 
( 3 ) 
Similarly, if H be the inclination of two planes passing through the line joining the 
centres of the sun and earth and the poles of the sun and ecliptic respectively, we should 
obtain by a corresponding figure 
tanH=tan I.cos(© — N), (4) 
where I is the inclination of the sun’s equator to the ecliptic, and N the longitude of 
the ascending node. 
Further, let L be the heliographical longitude of the earth, Pig- 8. 
and D its latitude, then it will easily he deduced from figure 8, 
in which N C is part of the ecliptic, N M the solar equator, 
N the ascending node, C the position of the earth, K the 
pole of the ecliptic, P the pole of the sun, that 
