242 On a new Calculation of the 



frequently observed both stars, and have noticed that the dis- 

 tance between them has continually increased, its progress hav- 

 ing at length become so perceptible, that they are now 15 seconds 

 apart, which is three or four times as much as when I first 

 took special notice of their distance. The smaller star, which 

 is to the south, has, moreover, augmented in size and brilliancy." 

 This note is not accompanied by any details of measurement : 

 I know not if any were made ; but, considering how particular 

 the statement is, a further enquiry appears to be requisite ; and 

 we will therefore briefly refer to the most authentic observations 

 existing on the star in question. 



It is only lately that double stars, as such, have attracted 

 the notice of astronomers ; previously it was only the prin- 

 cipal star of a group whose position wa§ determined and 

 recorded in catalogues. It is thus that Flamstead, La Caille, 

 Lalande, and others acted in regard to double stars generally, 

 and amongst them to ^ Ursse Majoris. It cannot be supposed 

 that with the instruments they employed they did not see the 

 small accompanying star, which was noticed as existing by co- 

 temporary astronomers ; but what we have since called double 

 stars were considered by them as single independent stars, of 

 which the principal only was deserving of attention. It is not 

 in their works, therefore, that we can hope to find the infor- 

 mation we seek. Another circumstance may also have limited 

 their attention in regard to ^ Ursse, — it comes to the meridian 

 very nearly at the same time as Spica Virginis ; and as the 

 latter is one of those fundamental stars which were principally 

 regarded, the observations of ^ Ursse, it is probable, received 

 the less attention on that account. Nevertheless, the notices 

 which we are able to collect, though far from numerous, are 

 sufiiciently decisive to enable us to arrive at a satisfactory 

 conclusion. 



Bradley, in 1755, frequently observed both stars ; he records 

 them as being of the third and sixth magnitude, as at this day ; 

 his observations of A.R. and declination show the lesser to have 

 been 11 ".3 south of the principal star, and their angular dis- 

 tance 13".9. 



In a suite of observations published in 1784, by M. Bugge, 

 a Danish astronomer, there are some of ^ Ursae which are not 

 very precise, but at the end of one occurs the following note J 



