174 Tramactmis. — Miscellaneous. 



same as the solar lines. Such a result would surprise me much. The D. 

 sodium line, the E. iron line, the b magnesium line, and the F. hydrogen line 

 of the Sun have, almost certamly, their counterparts in the spectrum of a 

 Centauri. There can be little doubt that the physical constitution of this 

 great star is, in most respects, the same as that of the Sun. It is probable, 

 however, that a Centauri is less developed than the Sun ; for, as Mr. Proctor 

 has pointed out, its light is brighter than its mass would lead us to expect 

 it to be, judging from the light of our Sun, as compared with his mass. 

 While the mass of the star is to the mass of the Sun as 2 : 1 , the light of 

 the star is to the light of the Sun as 3 : 1. Now, if it is true, as physicists 

 have good grounds for believing, that the Sun is, and has been, very slowly 

 but surely losing his heat, just as our earth has most certainly lost an 

 enormous amount of hers, there must have been a time when the Sun and 

 his system were less developed, but far hotter and brighter than they are 

 now — when they formed, probably, as I said when speaking of y Cruets, a 

 white star — that is to say, there was, quite possibly, a time when the light 

 from our Sun bore the same relation to his mass as the light from a Centauri 

 bears to its mass. We may also believe that matters are less advanced in 

 the planets (if there are any) of this neighbouring system than they are 

 with us. 



a TrianguU. — The spectrum of this star is not very striking, but it is 

 rather curious, as showing, apparently, that the star is in a condition inter- 

 mediate between that of a Centauri and that of y Crucis. The lines of the 

 second class, and also the groups, are very faint, but they are there. It will 

 be seen that this fact has some bearing on the suggestion I made respecting 

 the gradual development of stars while speaking of y Crucis. Here it looks 

 as if we had, so to speak, caught a star in the act of changing from the 

 second to the third class. What I have seen of the sj)ectra of the stars, so 

 far, leads me to think it probable that if every star, down to the sixth mag- 

 nitude, could be examined even with my instrument, and mapped roughly, 

 it would be found that the spectra obtained could be so classified that a 

 series might be made, each member of which would differ fi'om the next 

 almost insensibly. This, of coiu'se, would take a long time to do, as small 

 stars can be examined only in very fine weather. When it was done, how- 

 ever, the results would be very valuable and interesting. 



a Grids. — This is a second-magnitude white star, with the usual spec- 

 trum crossed by distinct hydi'ogen lines. 



/3 Grids is a second-magnitude star, and nearly as bright as the lucida 

 of this constellation. Its colom* is reddish-orange, and its spectrum is 

 much like that of y Crucis, but the groups of lines are not so distinct, 

 and, generally, there is a sort of approach to the appearance presented by 



