541 



a Pavonis - - 



78° 



$ Gruis - - - - 



75 



|S Canis majoris - - 



73 



oc Leporis - - 



71 



a Ramphasti 



70 



0 Leporis - - * - 



70 



a, Columbae - 



68 



0 



67 



% Canis majoris - 



66 



a Phoenicis - - - 



65 



y Gruis - - 



• 58 



f Canis majoris 



■ 51 Z. 



a in the Indian - * 



. 50 



C Canis majoris - ■ 



• 47 



It is more difficult to determine whether % in the Indian 

 have half the light of Sirius, than to recognize whether a. 

 in the Crane be nearer the brilliancy of Sirius than that of 

 a in the Indian. Comparing Betelgueuse and a in the Pea- 

 cock to a in the Crane, we find, that Betelgueuse must be 

 placed between a of the Crane and Sirius, and a of the Pea- 

 cock between « in the Crane and a in the Indian. The 

 narrower the limits, the more easy it is to avoid mistakes ; 

 especially if we try to arrive at the same numerical result by 

 two different ways. For example, a in the Crane and Pro- 

 cyon may be compared either directly 3 or by equalizing 

 with a reflecting instrument the light of Procyon and Ca- 

 nopus, and of Canopus and of a in the Crane ; or lastly, by 

 comparing a in the Crane and Procyon through the inter- 

 medium of Rigel and Sirius. Herschell classes the stars of 

 the Great Dog in the following order, a, t, /3, u. In the 

 Crane there is at present much less difference between « and 

 /3 than between (8 and 7. Respecting the relative intensity 

 of the light of Sirius and Canopus, the opinions of astrono- 

 mers who have visited the equinoxial zone have been singu- 

 larly divided. I believe I have determined by a great many 



