1892.] Stellar Photometry. 407 



Average Results by Methods 1, 2, and 3. 



fetar s designation. 



Magnitude. 

 Pritchard. 



Illuminating 

 power found. 

 Candle at 

 109 feet. 



Theoretical illu- 

 minating power on 

 the assumption 

 that mag. 2 = 

 -00075 candle at 

 109 feet. 





+ 0-86 



-0039 



-0041 





0-08 



-0017 



-0020 





1-12 



-0015 



-0017 





1-79 



-00075 



0-00090 



/3 Tauri 



1-79 



0-00085 



-00090 





1-94 



-00125 



-00080 





2-02 



-00074 



-00074 





2-05 



-00081 



-00072 





2-05 



-00085 



-00072 





2-26 



-00045 



-00059 





2-26 



-00035 



-00059 





2-33 



-00062 



-00055 





2-47 



0-00031 



-00048 





2-72 



-00042 



0-00038 





3-03 



0-00018 



-00029 





3-02 



0-00029 



-00029 



\ n » 



4-46 



-000040 



-000080 





4-54 



-000044 



-000070 





4-65 



-000025 



-000065 



B.A.C. Cat. 6754 Cygni .... 



5-27 



-000015 



0- 000037 





5-87 



-000013 



-000021 



The atmospheric absorption of light is discussed, and instances 

 given of the considerable diminution in the light of a star when no 

 apparent cause was discernible to ordinary observation. 



Eight determinations of the light of Jupiter have been made, the 

 average result being to ascribe to that planet a light equal to 

 0*020 candle placed at a distance of 109 feet. Determinations of the 

 light of the planet Venus and of the Moon are also given, and the 

 necessity for farther observations referred to. 



The total quantity of light afforded by the stars (apart from the 

 planets) is calculated from the above results combined with Arge- 

 lander's estimate of the number of stars down to the ninth mag- 

 nitude. Assuming that the light afforded by these is equalled by the 

 innumerable stars of lesser magnitude than the ninth, and by nebulae, 

 total starlight will equal that from 1-446 candles when placed at a 

 distance of 109 feet. If it be further assumed that only one-sixth of 

 the stars are capable of illuminating a given surface at the same 

 moment, then such illumination will be equal to that afforded by one 

 standard candle placed at a distance of 210 feet. 



