326 
Proceedings of the Royal Irish Academy. 
It is easily seen that 
. ^ cos (nSA - Q) 
a = AC ^ ; -f 
cos X 
^, , cos 30"- 43' 
-= 2" 1-425 
008 44^41' 
= 2"-591. 
We have yet to make a small change in the value of Q. We can 
calculate the quantity 0 - Q, when we know the time and the other 
elements. The difference between 9 - D. thus computed, and the ob- 
served value of 0 gives a value of Q. This quantity has been thus 
deduced from the observations, and the mean value is 
103°- 6' 
Collecting the results, we have 
TABLE Y. 
JV^ew Approximate Elements of the Binary Star f Ursae 
Majoris. 
Semi-axis 
Major. 
Eccentri- 
city. 
Position 
of Node. 
Inclina- 
tion. 
Angle 
between 
Major axis 
and line 
of Nodes. 
Period in 
Years. 
Mean 
Motion. 
Perihelion 
Passage, a.d 
a 
2"-691 
e 
0-3786 
Q 
103O-6 
r 
630-1 
X 
1350-3 
P 
59 88 
n 
60-012 
£ 
1816.405 
In Table YI. will be found the comparison of the angles of position, 
computed by the new elements, with those given by the observations. 
The observations which have been employed are the same as those 
of Table II., with two more (Nos. 22 and 23) added. 
