80 : Double Stars and the 
the primary. 
_-Itis remarkable that among the double stars, newly dis- 
covered, there are several whose proper motion is already 
known. I will here mention only the brilliant star y of the 
Whale, composed of a star of the third magnitude and one 
of the seventh; No. 42 in Berenice’s Hair, composed of two 
stars of the sixth magnitude, remarkably near each 
and y of the Crown, which, on account of the great proxim- 
Our catalogue presents a considerable number of double 
stars of this description, a part of which had probably esca- 
ped former observers by the difficulty of distinguishing them. 
7 Of Hercules, and y of the Crown may be considered, in 
this respect, as real touch stones of the perfection of tele- 
scopes, and they may serve to compare the power of these 
instruments, with that of the great telescope of Fraunhofer. 
I have examined with this instrument, the double stars of 
Herschell, a portion of which, such as ¢ of Hercules, and é 
of the Swan had become single according to his own ob- 
tly; for the moment will surely arrive in 
anion will remove from the star whose brill- 
The extraordinary force of our instra- 
ment accounts also forour seeing many stars triple, which 
vere before only regarded as double. Thus Sir W. Her- 
chen saw the star No. 7 of Taurus, asa double star of the 
fourth elass, and all subsequent observers have so regarded 
