Pope. — On the Southern Stm's and other Celestial Objects. 16^ 



its sensitiveness to the feeble red, orange, and yellow rays of the small 

 star return, and it sees the small star to be white or nearly so. On the 

 other hand, I have often noticed that the longer one looks at a double star 

 of this kind, both stars being in the field, the more pronounced does the 

 blue become. There is only one instance, that I am aware of, in which 

 this theory will not hold good. The small companion of a Scorpii is un- 

 doubtedly really greenish. I saw it on the 23rd of March, 1878, emerge 

 from behind the moon after an occultation while its bright companion was 

 still hidden, its colour then was a pale pea-green. There could have been 

 no contrast here, except with the moon's light ; admitting this exception, 

 however, it seems to me highly probable that while, in such wide double 

 stars as tt Argus and y Crucis the orange or yellow star is really what it 

 seems, the star that appears green or blue is, as a rule, really white. If 

 this view is the correct one, it follows that those observers who spend a 

 great deal of time in observing the tints of the companions to large stars, 

 are, to a great extent, wasting their time. 



y Argus. — This fine second-magnitude multiple-star has a very curious 

 spectrum. It belongs to a very small class of stars, the only other one 

 that I have heard of is in the Northern constellation Cassiopeia. In the 

 spectrum of y Argus there are certainly three very bright hues, one rather 

 faint, and, I believe, many finer ones. I am almost certain, too, that there 

 are several fine dark lines in the spectrum. The brightest line is, not 

 improbably, the F. hydrogen hne ; and the somewhat fainter one, the C. 

 hydrogen line. Of the other two very distinct bright luies, one is certainly 

 not very far from the position of the D. sodium Ime ; but I cannot place 

 the other. The presence of bright hues in the spectrum renders it far 

 more difficult than usual to estimate the positions, but the other line seems 

 to be about one-third of the distance from D. towards the u-on hne E. Not 

 improbably then, outside the photosphere of y Argus, there are ever-present 

 enormous masses of hydrogen and sodium, as well as other substances in the 

 gaseous condition, which have been ejected from the more central parts o 

 this sun ; and, the temperature of these incandescent gases being much 

 higher than that of the solar photosphere below, their spectrum is super- 

 imposed on the ordinary spectrum of the star proper. 



e Argus. — This yellow star belongs to Secchi's second class. In these 

 stars the luaes are very fine, and not easily seen unless the weather is very 

 favourable. To this class our sun belongs. In the spectrum of e Argus 

 the F. line can be seen pretty easily, but the D. sodium line seems to be 

 the most distinct of this spectrum. 



/3 Argus. — Magnitude, one and a-half. Colour, white. A first-class 



star. The hydrogen hnes are pretty broad and distinct. 



15 



