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XI. On the parallax of the fixed stars. By John Pond, Esq . 
Astronomer Royal, F. R. S. 
Read February 20, 1817. 
It is now very generally known to astronomers, that, for 
several years past, Dr. Brinkley, with the eight feet circle 
of the Observatory at Dublin, has constantly observed a perio- 
dical deviation of several fixed stars from their mean places ; 
which strongly indicates the existence of an annual parallax 
in those stars. The magnitude and perfection of the instru- 
ment, the regular continuation of the same result without 
exception, during a period of several years, and above all, the 
judicious reflections of Dr. Brinkley, and his unprejudiced 
statement of every objection that might be supposed to occur, 
seem to leave but little doubt upon the subject. Thus much 
at least is certain, that the observed discordance arises from 
some very permanent cause, and is totally distinct from what 
has usually been termed error of observation. 
The deviation from the mean place resulting from the 
supposed parallax being a very small quantity (never ex- 
ceeding a single second), Dr. Brinkley was naturally 
desirous that the result of his observations should be con- 
firmed by other astronomers. Few, however, are fortunate 
enough to possess instruments sufficiently accurate either to 
confirm or confute the hypothesis above stated. 
The mural circle at the Royal Observatory, erected in the 
