40 
Mr. Pond on the changes in the 
the accuracy of any results, with whatever care the observa- 
tions may have been made, which appear to militate against 
any received theory of astronomy ; and I shall have occasion 
myself to show, from the great discordances between instru- 
ments of the highest reputation, that this distrust is but too 
well founded. More particularly ought our suspicion to be 
excited, when such anomalies are found to exist, as bear some 
direct proportion to the zenith distances of the stars observed. 
In all such cases we should never hesitate, I think, to ascribe 
the anomalies to defective observation. If therefore in the 
present instance, any part of the discordances in question can 
be shown to depend on polar or zenith distances, I shall 
willingly admit, as to such part of them at least, that they 
are no otherwise of importance, than as affording data for 
leading to the detection of some hitherto undiscovered errors. 
The anomalies, however, that have led me on to this enquiry, 
and to which alone I attach any importance, are found to de- 
pend rather on the right ascensions, than on the declinations 
of the stars. Accordingly I found, while collecting observa- 
tions to form a catalogue for the present period, that I could 
more nearly predict the deviation of a star from its computed 
place, by knowing its right ascension, than its declination. 
Now it is not easy to conceive in what way the error of an 
instrument for measuring declination, fixed in the meridian, 
can be occasioned by any circumstance depending on the 
right ascension of a star to be observed. 
The general nature of the deviation of the stars from their 
computed places will be best understood from the annexed 
tables ; in one of which the principal Stars of the Greenwich 
Catalogue are arranged according to north polar distance, 
and in the other, in the order of their right ascensions. 
