594 Proceedings of the Royal Irish Academy. 
Some of the later measures are :- 
1883*25 • 
183° 
• 90 
0"-194, 
"Rn 0*plTllflTlTl 
1883-55 
: 182 
-50 
: 0 
•23, 
Burnliam. 
1884-71 : 
197 
75 : 
0 
•32, 
Engelmann. 
1886-91 
219 
•5 • 
0 
•39, 
j> 
1887-86 
286 
•3 
0 
•20, 
Schiaparelli. 
1888-65 
310 
•1 
0 
•29, 
Burnliam (7 nights). 
1889-50 
314 
•2 
: 0 
•31, 
„ {A.N., 2957) 
52. X Cygni = O 5 413. The arc described by the companion 
since its discovery in 1842 amounts to about 50°. Glasenapp's orbit 
represents the measures fairly well. 
Some recent measures are : — 
1886-516 
1886- 78 
1887- 584 
1887- 826 
1888- 83 
77°-39 
75 -50 
69 -98 
71 ^81 
70 ^60 
©"•60, Tarrant (^.iV., 2866). 
0 ^77, H. Struve. 
0 ^67, Schiaparelli. 
0 ^63, Tarrant {A.N.y 2899). 
— H. Struve. 
53. 4 Aquarii = 2 2729. The companion has described an arc of 
about 180° of the apparent orbit since its discovery by Sir W. Herschel 
in 1783. 
Some recent measures are :■ — 
1881-52 : 159°-6 
1887-823 : 170 ^49 
0"^52, Burnham. 
0 -53, Tarrant {A.N., 2899) ; 
measured distance too large." 
54. 61 Cygni = % 2758. This famous star has long been suspected 
of being a binary pair, but the matter seems still somewhat doubtful. 
If really binary the period is very long. 
The following are some recent measures : — 
1886- 855 : 121°-03 
1887- 68 : 121 -0 
21''-06, Tarrant {A.N., 2866). 
20 -58, Schiaparelli. 
Burnham says {A.K, 2957)—'' 1889-463 and 1889-502. Both stars 
single in the 36-inch with powers up to 1000." 
An observation of Bradley's gives : — 
1753-80 : 35°^4 : 19"^63. 
