84 SPECIAL RESULTS IN THE URANOLOGICAL 



of the Moon with the double star a Oentauri in the southern 

 heavens, the third in brightness of all the fixed stars, has 

 attempted to determine the ratio between the intensity of the 

 solar light, and the light of a star of the 1st magnitude ; ful- 

 filling thereby (as had been earlier done by Wollaston) a 

 wish expressed by John Michell ( 161 ) in 1767. From the 

 mean of 11 measurements made with a prismatic apparatus, 

 Sir John Herschel found the full moon 27408 times brighter 

 than a Centauri. Now the light of the Sun is, according 

 to Wollaston, ( l62 ) 801072 times greater than that of the 

 full moon ; whence it follows that the light which the Sun 

 sends to us is to that, which we receive from a Centauri 

 about as 22000 millions to 1. Hence it would follow with 

 great probability that, if we take into account the distance 

 of a Centauri according to its parallax, its inherent (absolute) 

 |ight would be 2' 3 times as great as that of our Sun. 

 "Wollaston found the brightness of Sirius 20000 million 

 times less than that of the Sun; and according to what 

 is now supposed to be known in respect to the parallax 

 of Sirius, (0"'230), its actual (absolute) .light would be 

 63 times greater than that of the Sun. ( 163 ) Our Sun 

 would thus be, in regard to the intensity of its light, 

 one of the fainter of the fixed stars. Sir John Herschel 

 estimates the light of Sirius as equal to that of nearly two 

 hundred stars of the 6th magnitude. As from analogy with 

 what we already know it is very probable that all cosmical 

 bodies change their place in space, as well as the strength 

 of their light, though it may be only in very long and un- 

 measured periods of time, and remembering the dependence 

 of all .organic life on temperature and the strength of the 

 Sun's light, the improvement of photometry appears deserving 



