34-0 An Account of a new Catalogue of Stars, 



a" Aberration et de Nutation: Modena, 1807. And the latter, 

 Tabulce Speciales Aberrationis et Nutationis, &c. Gotha, 1807: 

 2 vols, octavo. In this last-mentioned work, the second vo- 

 lume only is devoted to the tables of aberration and nutation; 

 and each star occupies a whole page. The first volume con- 

 tains much useful information connected with the same sub- 

 ject, and many other valuable tables. 



" Hitherto the attention of astronomers had been confined 

 to about five hundred of the principal stars : and in this state 

 the subject remained till the year 1812, when some new tables, 

 differently constructed and of a more general kind, were pub- 

 lished by Baron Zach. These are the most comprehensive 

 as well as the most convenient set of tables, which have hi- 

 therto been formed for such computations. They are entitled 

 Nouvelles tables d' Aberration et de Nutation pour 1440 etoiles; 

 and were published at Marseilles in 1812, in one volume oc- 

 tavo. But, in these tables, the solar nutation, as well as some 

 other minute quantities, are wholly omitted: and although 

 that celebrated author has given a rule (in page 26) whereby 

 we may approximate to the value of the solar nutation, yet 

 that rule is not strictly correct, and ought not to be resorted 

 to in the present state of the science. 



" I would observe, that when we wish to compute the aber- 

 ration and nutation by the tables of Baron Zach, here alluded 

 to, it is necessary to form distinct arguments for the sines of 

 the quantities employed ; the logarithms of which quantities 

 must be sought for, and taken out of a book of logarithms. 

 And, for the purpose of forming the arguments, reference 

 must be made to some ephemeris ; and certain proportional 

 parts must be computed before a correct solution can be ob- 

 tained. We have then to obtain the sums of four logarithms, 

 and to find the natural numbers corresponding thereto. After 

 this, we have to compute the precession and solar nutation 

 for the given day, by a separate calculation of no little trouble, 

 before we can deduce the total correction. Those only, required 

 who are versed in such calculations, can fully appreciate the la- 

 bour, the risk of error, and the loss of time concerned in these 

 several operations. 



" By the method, however, which I am about to explain, 

 nearly the whole of this troublesome process may be saved. 

 For, in most ordinary cases, it will not be necessary to form 

 any argument, nor in any case to refer to an ephemeris, or 

 any other work, except to a small table of logarithms. We 

 have merely to add four logarithms found in one of the pre- 

 sent tables, to four logarithms found in another of those tables, 



and 



