'Decllnatiuii of some of the principal Fixed Stars,. 1 79 



exceptionable construction), will be cautious in admitting the 

 accuracy of any results, with whatever care the observations 

 may have been made, v/hich appear to militate against any re- 

 ceived theory ot astronomy; and I shall have occasion myself 

 to show, from the gi'eat discordances between instruments of 

 the highest reputation, that this distrust is but loo well founded. 

 More particulai'ly ought our suspicion to be excited, when 

 such anomalies are tbund to exist, as bear some direct pro- 

 portion 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 pre- 

 sent instance any part of the discordances in question can be 

 shown to dej)end on polar or zenith distances, I shall willingly 

 admit, as to such part of them at least, that they are no other- 

 wise of importance, than as affording data for leading to the 

 detection of some hitherto luidiscovered errors. The anoma- 

 lies, however, that have led me on to this inquiry, and to which 

 alone I attach any importance, are found to depend I'ather on 

 the right ascensions, than on the declinations of the stars. 

 Accordingly I found, while collecting observations to form a 

 catalogue tor the present period, that 1 could more nearly pre- 

 dict the deviation of a star from its computed place, by know- 

 ing 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 occa- 

 sioned 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. 



From these tables it will appear, according to my statement 

 in the former part of this jiaper, that the general tendency of 

 the deviation is towards the south ; that in about one-third 

 part of the heavens in right ascension this southern tendency 

 is very inconsiderable, and would hardly have excited atten- 

 tion: for in this part, stars between the zenith and the pole, 

 appear a very small quantity to the northward; whereas in 

 the remaining and most considerable portion of the heavens, 

 every star appears to be a considerable quantity to the south 

 of its computed place; and witli few exceptions, the more 



• As our limits do not ciwblc us to insert these tables, we cmi only re- 

 fer tiie render to tliem in the IMiilobophital Transactions for 1823, Part I. 

 page 61, (^c— Edit. 



Z 2 southward 



