456 Memoirs of the Astronomical Society. [Dec. 



these catalogues were brought up to 1830 by means of the an- 

 nual variations annexed to the latter catalogue. 



**On a comparison of these several catalogues it appears that, 

 as to the Hight Asceusions, the catalogue of the Astronomical 

 Society falls far within the limits of the errors of observation : 

 since more than two-thirds of the stars there compared are 

 between the mean places as severally given by these eminent 

 observers : and in those instances where this is not the case, 

 the position does not differ so much from that of some one of 

 the observers, as those observers do from each other, and from 

 themselves. 



** With respect to the North Polar Distances recourse was had 

 to the two catalogues of Mr. Pond: one reduced to 1818, 

 (being the last correction of his Standard Catalogue of 1812-13, 

 prior to the derangement of the mural circle) and published in 

 the Nautical Almanac for 1820 : the other reduced to 1825, and 

 taken from the Nautical Almanac for 1829, above mentioned. 

 These were brought up to 1830 by means of the annual varia- 

 tions annexed to the latter catalogue : and which differ, in some 

 instances very considerably, from the values annexed to the 

 catalogue of 1818. Out of the 70 comparisons made, it will be 

 found that in nearly one half of them the difference is below 

 one second ; that in 16 others the difference is below two se- 

 conds ; and that in 7 others the difference is below three seconds : 

 whilst the difference in the remainder (which in five cases, only, 

 exceeds four seconds) may be considerably reduced by the 

 adoption of the annual variations annexed to the catalogue of 

 1818 ; the difference of which will in fact, in many of the com- 

 parisons, amount to a quantity equal to the whole of the differ- 

 ence in question. Indeed, a difference in the mode of reduction 

 will frequently account for differences, as great as any that 

 occur in these comparisons." 



The mean difference of each catalogue from that of the As- 

 tronomical Society is inserted at the bottom of the respective 

 columns': and will be found as follows : 



Bessel, 1815 = - O-004'l 



1825 = + 0-151 I 



Brinkley, 1824 = + -017 ^ Right Ascension. 

 Pond, 1819 = + 0-023 I 



1825 = + -351 J 



