336 M. Struve’s Observations on Double' Stars. 
M. Struve is disposed to believe that the two stars belong to the 
same system of attraction, since the proper motion of both is 
in the same direction. 
67. 57 Eagle, R. Asc. 19^ 45^ S. Decl. 8*^ 42\ 
6th and 7th Mag. 
The difference of R. Ascension observed in 1819 is + 0".295 
and that in declination 5'. Hence the angle of position is 78° 
S. Foil. Sir W. Herschel makes the angle 82° S. Free. ; so 
that the angle has changed about 20°. 
68. 4- Swan, R. Asc. 19^ 51'. N. Peel. 51° 58'. 
4th and 7th Mag. 
The small star precedes the great one to the south. Their 
distance is two diameters of the great star. M. Struve computes 
the angle of position to be 90° S. Free. Sir W. Herschel made 
it 89° 30' N. Free. Hence, there has been a change of 180°, 
69. X Cepheus, R. Asc. 20^ 15'. N. Decl. 77° Kf. 
In 1818 and 1819 M. Struve found the difference of R. Asc. 
to be -p l".79, the angle of position 36° 2' S. Fob, and the dis- 
tance 7". 08. Sir W. Herschel makes the angle of position 32^^ 
30', and the distance 7".08, 
70. 15 Dolphin. R. Asc. 20^ 22'. N. Decl. 10° 45'. 
6th and 6th-7th Mag. 
The difference of R. Asc. is — 0".95, the angle of position 
15° S. Free., and the distance 14".5. Sir W. Herschel found 
the distance in 1779 to be 12".5, and the angle of position 10° 
S. Free. 
71. 52 Simn, R. Asc. 20^ 37'. N. Decl. 30° 4', 
4th and 9th Mag. 
The difference of R. Asc. is -j- 0". 48 ; the angle of position 
35° 9 N. Foil. ; and hence the distance is 7". 69. In 1780, Sir 
W. Herschel observed this angle to be 28° N. Following, 
