the effects of parallax , &c. of certain fixed stars. 339 
2. The fixed telescope, used by Mr. Pond for the com- 
parison of u Cygni and (3 Aurigae, shows no relative changes 
of place that can be explained by attributing a parallax to 
a Cygni. This star formerly appeared to have a less parallax 
than others I had observed. My new observations give a 
much smaller quantity for it ; but I am inclined to think the 
true quantity lies between my present and former results. 
Now admitting it to be half a second, no contradiction to 
this can be drawn from the observations by the fixed tele- 
scope, when those observations are carefully examined with 
a reference to the visible effects of the change of temperature 
The fixed telescope used for a. Aquilae made the comparison 
by 55 l Pegasi. Now, the same maxima of parallax in de- 
clination of this star and of a. Aquilse occur within a few days 
of each other, so that it is completely the difference of paral- 
lax that is ascertained by comparing this star and a Aquilae ; 
and my results in Table 3 show, that in this part of the 
heavens we cannot conclude any thing as to the absolute 
parallax of one star by its relative parallax to that of another. 
Thus I cannot but venture an opinion, that nothing certain 
has hitherto been determined by the use of the fixed tele- 
scopes. 
3. The results of the investigation of the parallax of ot 
Aquilag, by observations in right ascension, are still less 
satisfactory. The stars Mr. Pond has principally used for 
determining the error of the clock, are those in which I find 
the principal discordances, as will appear by a reference to 
the Greenwich observations ; and consequently, those results 
ought to afford no appearance of parallax. 
If stars opposite in right ascension be used, the utmost 
mdcccxxi. X x 
