54 



motions. — I was therefore led to expect that on comparing the 

 places of the small Stars of Aquilae with a Aquilae, I should find 

 changes had taken place both as to the position of the Stars in 

 respect to a Aquilae, and with respect to each other. — The obser- 

 vations were made last Autumn. The diflferences of right ascen- 

 sions and of North polar distances of four small Stars, and of a 

 Aquilae which had been observed by Dr. Maskelyne in 1765, were 

 ascertained. On reducing the observations, the results were found 

 different from what I had expected. I found that the four small 

 Stars preserved exactly the same positions with respect to each other 

 as resulted from Dr. Maskelyne's observations in 1765. It follows 

 therefore, that these four Stars, considerably distant from each other, 

 have not perceptibly moved during the last seventy years, or have 

 moved in the same direction, and with a common velocity. The 

 latter supposition is very improbable when considered with a re- 

 ference to a. Aquilae, whose relative position to these Stars is very 

 considerably changed. Taking these stars as fixed, the proper 

 motion of a Aquilae is thereby ascertained with considerable pre- 

 cision. 



I have also, by the observations of small Stars near a Cygni, been 

 enabled to derive an independent proof of the fixedness of that Star. 

 Among the Stars observed by Dr. Bradley, and of which the mean 

 places are given for 1755 in the Astronom. fundamenta, are three 

 small Stars so near a Cygni that we may reasonably rely that the 

 differences of the right ascensions and declinations of them and a 

 Cygni were correctly taken. — These stars have during the last 

 Autumn been again compared. It will be considered a curious 

 circumstance, that less than ten degrees from an apparently im- 

 moveable group of Stars (one of them (a Cygni) of the first or 

 second magnitude,) there are two Stars of the sixth magnitude that. 



