160 Mr. Pond on the parallax of the fixed stars. 
could be compared with others passing through the same 
field. This suggestion was approved of by the visitors, and, 
till a proper building can be contrived and erected, I have 
fixed two ten feet telescopes, one on the circle pier directed 
to a Aquilae, and one on the quadrant pier directed to « Cygni, 
and with these temporary instruments I am about to com- 
mence a series of observations. 
The advantages I presume those instruments to possess 
are, length of radius; great steadiness, and simplicity of con- 
struction ; and being used only for a few T select observations, 
these few are more likely to be made with extreme care. 
Although, for the reasons above stated, I was unable to 
devote the mural circle entirely to the investigation of 
parallax, yet during the summer of 1813, and the following 
winter, I was induced to continue the telescope in the same 
position, with the view of examining any changes that might 
occur indicative of parallax, or any other irregularity. During 
this period, the three principal stars observed by Dr. Brink- 
ley (a Lyras, a. Aquilze, a. Cygni) arrive at their maximum and 
minimum of parallax ; as far, therefore, as the observations 
of one single year can be supposed to have any weight, these 
seem, I think, to be as good as ever may reasonably be 
expected to be made with the same instrument. 
The object of the present communication is to submit the 
result of these observations to the Society ; and whatever 
remarks I may be induced to make on the discordances be- 
tween Dr. Brinkley’s observations and my own, I hope, 
will be considered rather in the light of suggestions, aris- 
ing from circumstances obviously presenting themselves to 
our notice, than as arguments to decide a question, which 
