166 Transactions. — Miscellaneous. 
serve to give us a certain amount of information that can be thoroughly relied 
on; they enable us to state, further, that the existence of certain physical 
conditions, and the presence of certain elementary substances in certain 
stars, are highly probable; and, possibly, they are calculated to create or 
stimulate in us a desire to learn more certainly and fully the constitution 
and physical habitudes of the stars. 
The objects are treated of in the order of their Right Ascension, and 
the places of the stars, when given, are taken from the ‘‘ First Melbourne 
Catalogue," epoch, 1870. 
The first star on the list is Achernar, or a Eridani. This fine first 
magnitude star is very nearly pure white, without any discernible tint, 
except possibly a slight shade of blue. This star belongs to Padre Secchi’s 
first class of stars, the type of which is the giant sun Sirius. In the 
case of typical stars of this class, the spectrum is remarkable for the great 
breadth and distinctness of the hydrogen lines. Indeed these stars are for 
convenience often called **the hydrogen stars." All of them are white, or 
bluish-white. In Achernar the hydrogen lines are not nearly so strongly 
marked as they are in some others of the class. Indeed the star by no 
means nearly approaches the type, and is probably to be considered as 
holding a position between such stars as Sirius and stars of the second 
class, like Procyon, though much nearer to the former than to the latter. 
a Eridani.—This beautiful little double-star is just visible with the naked 
eye in fine weather. It is about one degree from Achernar, north follow- 
ing. The two components are of the same orange colour, and of very 
nearly equal magnitudes, 7 and 7. When Sir John Herschel measured 
this star (anno 1835-0), he found the angle of position with the meridian to 
be 122-8?. Powell, in 1868, found the angle to be 73:9?. Last week (say, 
anno 1879°75) the angle was 58°8°. The distances for the same dates are 
8°65", 4:88", and 5-3’. This interesting double is, therefore, very probably 
a binary star of comparatively short period. 
0 Eridani.—R. A. 2hrs. 58min. 19:9 secs. Decl. 40° 49'—85'17" S. In 
the Melbourne Catalogue, the magnitudes 5:2 and 6:2 are assigned to the com- 
ponents of this fine double star. "There is most certainly serious error here. 
The star is plainly, taken as a whole, a large fourth, or a small third-mag- 
nitude star. Probably magnitude 8:9 for the larger star, and 5:9 for the 
smaller one, would not be far from the truth. The colour of the larger 
star is yellowish-white, with a faint green tinge; the smaller is a light 
shade of indigo blue. Sir John Herschel's angle of position and distance, 
in the year 1835-75, were 81:5? and 8:68". The angle at the epoch 1879-75 
is 85-49. I have not been able to get a thoroughly satisfactory distance, 
but it is now somewhat over 10’. Time and accumulated observations will, 
