298 Dr. Brinkley on the 
the exertions that have been made here and at Greenwich. 
Several attempts to observe the parallax of the fixed stars 
have failed since the time of Dr. Hooke, and Mr. Flamstead,* 
and if this should end like the rest, it will be some satisfac- 
tion to have ascertained, beyond doubt, certain limits ; and 
also, probably to have occasioned these limits to be still 
farther circumscribed by the observations of Mr. Pond, in 
the event of his not confirming my conclusions. 
* See note (B). 
Observatory of Trinity College, 
Dublin, Feb. 20, 7818. 
Note (A). 
Upon examination of Dr. Bradley’s* account of the aber- 
ration, it will appear, I think, that the maximum of aberration 
deduced therefrom, cannot be depended on to £ of a second* 
Dr. Bradley afterwards mentions, in his paper on the nuta- 
tion, that he had revised his computation, and states 20" as 
the result nearest the truth. The result from the eclipses of 
Jupiter’s satellites, as deduced by M. Delambre, is 20^. The 
limit of the probable error of this latter determination is not 
easily known ; but it appears to me that we ought to adopt 
the result of Dr. Bradley’s revision, rather than any con- 
clusion we can deduce from the data in his first paper. We 
have not the original observations to refer to ; and it is to be 
remarked, that he puts down all the maxima of changes of 
* Phil. Trans, xxxv, 637, or Old Abridg. vi, 149' 
