260 ON THE LIGHT OF THE MOON AND OF THE PLANET JUPITER. 
Mean full Moon 
Log = log. [27408] + 9.962 — 9.769 — 0.026 + 0.012 = 4.617. 
a Centauri 
Hence, if we adopt the expression (29), and the values of H, determined from 
observation, Herschel’s result becomes, 
œ Centauri no wk 
Mean full Moon 41400 ` 
According to Seidel, the logarithm of the ratio between the light of Jupiter at its 
mean opposition and a Lyre is,* 
SY "e 
uper Mein opposed. D ol 
Log. 
P « Lyra 
Herschel's and Seidel's photometric determinations furnish the following numbers: + — 
HERSCHEL. SEIDEL. 
Sirius : Sirius : 
Log. —————, = 0.620 = 
og. " Coon Log. E Lyre = 0.621 
Rigel Rigel 
« —— — = 9,820 cu 
e Centauri Jc que e 
Kcu Le. E EL E 
a Centauri a Lyre 
& Er — 9.420 | « Fomalhaut — 9.526 
« Centauri e Lyre 
A iiM CES d 
« Centauri a Lyre 
whence we obtain: — 
Sirius œ Centauri e Centauri 
x —— = log. ——— ——— = 
Log. = log. = 0, 
gege" Lyre Sirius a Lyre ENI 
Rigel a Centauri 
e ium gh wm ee QE e SC 
a Lyre x Rigel ` oe 
“ Spica à ~~ e = € Ki = 0.187 
« Lyre Spica 
Fomalhaut . e Centauri S 
s L e g = 0.106 
ae Lyre ^ Fomalhaut 
a Se EE a 
a Lyre e Aquilae ` ` = 0.137 
* Untersuchungen über die Lichtstárke der Planeten Venus, Mars, Jupiter, und Saturn p. 34 
3 H . 
f Ibid, p. 31. 
