574 
Proceedings of the Royal Irish Academy. 
following formulae : — 
(1) 
w - € sin = /X {t-T). 
(2) 
tani v = 
(3) 
tan {Oc-il) = cos i tan {v + X). 
(4) 
p = a{l -e cosu) 
cos («? + A.) 
cos(6',-d)' 
where c is the eccentricity expressed in degrees = 57°"296 x ^ ; is the 
true anomaly for the epoch t ; Oc the required position angle, and p 
the distance. 
The ITotes give details respecting the probable value of the drfferent 
orbits, the masses of the binary stars, when the parallax is known, &c. 
Some recent measures of each object are also given, which may 
be of use to computers who may wish to recalculate the orbit of 
any particular binary. 
My best thanks are due to Messrs. Monck and Eambaut for 
valuable assistance and advice. 
mean annual motion = 
360° 
; u the eccentric anomaly, and v the 
