Dr. Brinkley on the 
g 9 2 
a Aquilae. 
The stars (3 and y Aquilae pass the meridian within a few 
minutes of the passage of a. Aquilae ; and as they are much 
inferior in brightness to that star, and differ less than 3 
degrees in declination from it, I considered that if I could 
observe the three stars on the same day, the comparisons of 
the observations in winter and summer would furnish much 
information relative to the parallax of « Aquilae. 
As the stars pass so nearly together, there was not suffi- 
cient time to read off the three microscopes for each observa- 
tion ; I therefore, for some time, read off only the bottom mi- 
croscope for 7, to be compared with the reading of the bottom 
microscope for «*, and the three microscopes for «, giving up 
the observation of ( 3 . Afterwards, I only read off the bottom 
microscope for «, and thus was enabled to observe ( 2 . Unfor- 
tunately from the few observations to be obtained in October 
and November, when the sun approaches these stars, I have 
not succeeded hitherto in obtaining a sufficient number of 
observations ; but my summer observations appear very satis- 
factory, in agreeing with the result from the former observa- 
tions of these stars, which were made in the autumn of 1813, 
and with Mr. Pond’s north polar distances; whereas the 
summer zenith distance of a Aquilae has been uniformly less 
than the winter zenith distance of that star. So that, as far as 
I have gone with this kind of trial, the results have been very 
strong in favour of the parallax of a. Aquilae. As in my recent 
observations of this star, only the bottom microscope has 
been used, I have deduced results from all my former obser- 
vations of a Aquilae from the bottom microscope only. 
