of the Orbits of Double Stars. 



177 



Lastly, Mr. Herschel calculates in the paper referred to, 

 from the observations of his father: 1S04-42, g = 2"-5625, 

 with which the orbit perfectly agrees. 



Viewing these differences, one might perhaps be inclined to 

 believe that these elements present a pretty near approxima- 

 tion to the truth. Some observations, however, made by 

 Struve, with his great refractor, which he has kindly commu- 

 nicated to me, give results so different with regard to the di- 

 stances, that an explanation appears almost impossible. Struve 

 observed : 



An orbit which during the angular motion of 10° presents 

 such differences in the distance would, even if it could be re- 

 conciled with the earlier observations subsequent to 1818, have 

 no trace of resemblance with the present one, as far as can 

 be judged from a rough estimation, 



N. S. Vol. 1 1 . No. 63. March 1 832. 2 A On 



