in the relative Situation of double Stars. 367 
As the equality of the two stars gives little room for admitting 
a difference in their parallactic motions, we cannot reasonably 
ascribe the change of situation to that cause; though, otherwise, 
the direction of such a motion in the largest of the two, would 
be sufficiently favourable. The situation of the stars being much 
insulated, a connection between them may be admitted, with a 
high degree of probability.* 
| Bootis. II, 18. 
The change in the situation of the two stars of this double 
star is very remarkable. The small star, April 15, 1782, was 
65° 53' north-following the large one. In one of my sweeps , 
April 20, 1792, I perceived the small star in the 20-feet re- 
flector ; and estimated its position, as it passed the field of view, 
to be about 85° north-preceding. When the sweep was finished, 
I found that this star could not be in the situation I had just 
seen it, unless it had undergone a considerable change since the 
year 1 782 ; and, that no mistake had been made in the estima- 
tion of this evening, appeared very clearly, by a measure taken 
of its position, which actually gave 85° 43', 5 north-preceding. 
This pointed out a retrograde motion of the small star. March 
22, 1795, the position was 84° 56'. April 1, 1802, 82° 37'; and, 
April 2, 1804, I found it 83° 54'. A mean of the two last 
measures, will give the present situation 83°26' north-preceding ; 
and the total change of the angle of position, in 21 years and 
352 days, will be 30° 41k 
If it should be remarked, that the measure taken in 1795 
* The calculation of the probability of a connection, which has been given in the 
Phil Trans, for 1802, page 484, makes it above 75 millions to 1, that these two stars 
are not situated as they are, by a mere casual scattering of them in space. 
MDCCCIV. 3 B 
