582 
Proceedings of the Royal Irish Academtj. 
18. <^ Ursae Ma j oris = O ^ 208. A close and difficult double star 
discovered by 0. Struve in 1843. 
19. y Leonis = % 1424. An arc of only about 33° bas been 
described since its discovery by Sir W. Herscbel in 1782. The orbit is, 
therefore, somewhat uncertain, and likely to remain so for many years 
to come. 
Some recent measures are 
1882-24 
114° 
-33 
: 3"^521, Engelmann. 
1882-28 
113 
•25 
: 3 
•56, Doberck. 
1883-27 
112 
•66 
: 3 
•344, Engelmann. 
1884-19 
113 
•30 
: 3 
.463, Perrotin. 
1885-12 
113 
•0 
: 3 
•45, 
1885-175 
112 
•37 
: 3 
•49, Doberck. 
1885-307 
115 
•39 
: 3 
•34, Tarrant. 
1885-99 
113 
•87 
— Doberck. 
1888-35 
114 
•0 
: 3 
•36, Schiaparelli. 
A list of measures by Dr. Doberck, from 1876 to 1882, will be 
found in the Transactions of the Eoyal Irish Academy, vol. xxix., 
part XIII. (1890). 
20. ^ Ursse Majoris = ^ 1523. This was the first binary star for 
which an orbit was computed (by Savary in 1830). More than a 
complete revolution has now been completed since its discovery by Sir 
W. Herschel in 1780. The period has, therefore, been well determined, 
and seems to be about 60 years. 
Some recent measures are as follows : — - 
1881-23 
270°-35 : 
r'-84, Doberck. 
1882-25 
262 
•10 
1 
•987, Engelmann. 
1882-25 
259 
•43 
. 2 
•00, Doberck. 
1883-32 
257 
•83 
: 2 
•002, „ 
1884-28 
248 
•02 
1 
•687, Perrotin. 
1884-41 
249 
•60 
1 
•920, Engelmann. 
1885-36 
. 245 
•2 
. 2 
•12, 
1885-414 
243 
•36 
: 1 
•87, Tarrant. 
1886-36 
237 
•4 
2 
•06, Engelmann. 
1888-29 
222 
•7 
1 
•64, Schiaparelli. 
A list of measures by Dr. Doberck, from 1875 to 1882, will be 
found in the Transactions of the Eoyal Irish Academy, vol. xxix., 
part XIII. (1890). 
