448 NOTICE OF THE ORBIT OF THE 
the last or the beginning of the present century; and that about twenty years 
hence the stars will probably be seen very near each other, or in apparent con- 
tact, but the data are at present insufficient to give even an approximation to the 
major axis of the orbit and time of revolution.” 
The next authority on the subject is Sir Joan Herscuet, who specially applied 
himself to the subject of the Southern double stars when at the Cape, and had 
far superior instruments for such a purpose to any of his predecessors; he thus 
describes and sums up all that was known to him of this star, in his recently 
published work. 
“This superb double star, beyond all comparison the most striking object of 
the kind in the heavens, and to which the discovery of its parallax by the late 
Professor HENDERSON has given a degree of astronomical importance no less con- 
spicuous,—consists of two individuals, both of a high ruddy or orange colour, 
though that of the smaller is of a somewhat more sombre and brownish cast. 
They constitute together a star which to the naked eye is equal or somewhat 
superior to Arcturus in lustre”’ After describing the magnitude which he con- 
sidered should be assigned to each, and which agrees more nearly with what I 
have already stated as being my own opinion, and after giving some optical and 
physiological reasons which may tend to explain the under-estimation of former 
observers,—Sir John then cites the fact of the remarkable amount of proper mo- 
tion of the stars, and says, “ This consideration alone suffices to decide us in ad- 
mitting a binary connection between them, and it will therefore be interesting to 
see what evidence observation furnishes of orbitual motion round their centre of 
gravity. For this, however, the data are somewhat precarious, as we have, until 
recently, only catalogued differences of A.R. and Polar distances, from which to 
calculate the angle of position and distance at the epochs of observation. ‘This 
done, and the results tabulated, together with my own positions and distances, 
obtained by direct measurement with the equatorial, we have as follows :”— 















Epoch of 
Authority. | Observation. Position. Distance. 
Lacaille, - 1750 218 44 20:51 
(Maskelyne, 1761 15:5) 
Fallowes, 1822 209 ~=—36 28:75 
Brisbane, 1824 215. 25 22:45 
Dunlop. 1825 2138 - 1% 22°45 
Johnson, 1830 215 2 19-95 
Taylor, | 1831 215 58 22°56 
Herschel, 1834-68 17-43 
1834-79 218 30 
1835-86 219 30 
1837-34 220 42 
1837-44 16°12 




