342 An Account of a nemo Catalogue of Stars. 



the annual variations attached to the catalogue of 1825. The 

 catalogue of the same stars by Dr. Brinkley was taken from 

 M. Schumacher's Astronomische NachricMen, No. 78 : it is 

 there reduced to 1824, but was brought up to 1830 by means 

 of the annual variations annexed thereto. The first catalogue, 

 in M, of Mr. Pond, was taken from that (reduced to 1819) 

 which is inserted in the Nautical Almanac for 1822; and was 

 the last that was published prior to his important alteration of 

 the position of the equinoctial points by the additiou of s '31 

 to all the stars. The second catalogue of Mr. Pond was that 

 (i-educed to 1825) which is published in the Nautical Almanac 

 for 1829, and contains the latest corrections, to August 1826. 

 Both these catalogues were brought up to 1830 by means of 

 the annual variations annexed to the latter catalogue. 



On a comparison of these several catalogues it appears that, 

 as to the Right Ascensions, 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 1 8 1 2-1 3, 

 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 men- 

 tioned. These were brought up to 1830 by means of the 

 annual variations 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 dif- 

 ference is below one second; that in 16 others the difference 

 is below two seconds ; 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 con- 

 siderably 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 comparisons, amount to a quantity 

 equal to the whole of the difference in question. Indeed, a 

 difference in the mode of reduction will frequently account for 

 differences, as great as any that occur in these comparisons : 

 as may be seen in our Journal for July 1825, page 33. 



The 



