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XXXI. On certain changes which appear to have taken place in 
the positions of some of the principal fixed Stars. By John 
Pond, Astronomer Royal , F. R. S. 
Read June 19, 1823. 
Since the date of my last communication on the subject of 
the deviation of the fixed stars from their computed or pre- 
dicted places, I have been induced to examine such interme- 
diate observations, as appeared likely to throw some light on 
this difficult subject. 
The observations that best deserve attention since the time 
of Bradley, are the few which were made by the French 
astronomers, in their Trigonometrical Operations, about the 
year 1793, and those of Greenwich, Armagh, Westbury and 
Palermo, some years later, as published in the Philosophical 
Transactions for the year 1806. As the computations and 
tables relating to this investigation are subjoined, it will only 
be requisite, briefly, to state the result. It appears tome, that 
these observations greatly add to the probability that some 
variation, either continued or periodical, takes place in the 
sidereal system, which, producing but very small deviations 
in a finite portion of time, has hitherto escaped notice. 
That in consequence of this, it becomes impossible, even 
if two perfectly exact observations of a star could be made 
at distant intervals, either by interpolation to assign its place 
for any intermediate period, or to predict its place for the fu- 
ture, contrary to the theory hitherto received. The nature 
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