88 Mr. Baily's proposed Tables, S^c. 



readily determine the amount for every tenth day, when we 

 wish to apply it to the computation of the annual tables *. 

 The values of N' and N'^ are given by Mr. Herschel. 

 M. Bessel has, in the formation of his subsidiary tables, added 

 the mean place of the star, at the commencement of the year, 

 to the amount of the lunar-nutation: by which means he saves 

 the computer the trouble of one addition. But, with de- 

 ference to so great an authority, I would suggest the propriety 

 of keeping those quantities distinct. 



16. Having thus given a sketch of the manner in which 

 auxiliary tables may be formed, so as to render Mr. Herschel's 

 tables more generally applicable and useful, and at the same 

 time to enable us to obtain more easily the necessary correc- 

 tions for the Greenwich stars, I trust that some one will be 

 induced to pursue the subject still fiirther, and endeavour to 

 procure the actual computation of such auxiliary tables for 

 the correction of all the principal stars now observed at the 

 Observatory at Greenwich. The number of those stars was 

 formerly 36; and these are the stars whose corrections in 

 right ascension have been tabulated by M. Bessel : the cor- 

 rections in declination being still a desideratum. The num- 

 ber in Mr. Herschel's tables is 46 : and the whole of these 

 might be tabulated in the manner here proposed, without any 

 considei'able trouble. But Mr. Pond has recently extended 

 his list to 60 stars, whose apparent places are now given an- 

 nually in the Nautical Almanac : and at the end of the volume 

 for 1829, is given a Catalogue of one hundred principal fixed 

 stars. Whether it is intended to give the apparent places of 

 the whole of these, I know not; but it is evident that the 

 more the list is extended, the more desirable it will be to save 

 the time and labour of the computer : and in no way can this 

 be so effectually done as by the tabular arrangement here 

 proposed. 



As your Journal appears to be very extensively circulated 

 on the continent, as well as in this country, I beg leave to take 

 this opportunity of correcting a slight typographical error in 

 my Introduction to the New Tables for facilitating the com- 

 putation of Precession, Aberration and Nutation, which may 

 probably mislead some persons who may employ those tables 

 for a different meridian to that of Greenwich. The error oc- 

 curs in page xx, where the accetit has been placed on the 

 wrong h: therefore in line 10 for (h) read {h'), and in line 



• As an example, take the case of a, AepdlcB on the tabular April 11th. 

 These values will be found equal to —0^-2065 + 0'-0039 = — 0'-2026. 



12, for 



