1863.] 



Sir J. Herschel — Catalogue oflsfehulce. 



3 



extensive and of a nature to be safely entrusted to other hands, the Royal 

 Society, on the application of the compiler, readily and most liberally con- 

 sented to supply the funds for defraying the necessary expense of this 

 operation. On consultation with the Astronomer Royal, it was resolved 

 that the places having been first roughly brought up to 1860, the places so 

 obtained should be used to compute the precessions for 1880, by the ap- 

 plication of which to the original places the final and exact places for 1860 

 should be obtained and entered up. This will secure the availability for 

 the use of observations, of the present Catalogue, without fear of material 

 error up to the year 1930 at least. The actual computation was executed 

 by Mr. Kerschner, one of the computists employed at the Royal Observa- 

 tory, the Astronomer Royal kindly undertaking the arrangement and super- 

 vision of the work. The computations were made on printed forms, and 

 are preserved for reference. 



The Catalogue is arranged in general order of right ascension — in co- 

 lumns, containing a current general number, four columns of synonyms 

 and references to the original authorities ; the right ascension, precession 

 in R.A., and the number of observations on which this element relies; a 

 similar set of columns for the North Polar distance, and a brief descrip- 

 tion, in abbreviated language, of the object, deduced from a careful compa- 

 rison inter se of all the descriptions given in the original observations. 

 Lastly, are appended two columns, — the one containing the total number 

 of times the object has been seen by Sir AVm. Herschel and by the author 

 of the present paper ; the otber, references to a series of notes annexed at 

 the end of the Catalogue, and to a general list of places where engraved 

 figures of the objects will be found. 



The notes so appended contain remarks on every particular brought 

 under discussion as affecting the evidence on which the adopted places 

 rest, and whatever else may be considered requiring explanation in refer- 

 ence to each object. In particular they give the results of a very careful 

 comparison of the present Catalogue with the elaborate catalogue (for 

 1830) of M. Auwers, already mentioned, of the existence of which the 

 compiler was not aware till the whole of the computations had been com- 

 pleted and the present Catalogue arranged and copied out. This com- 

 parison has led to the detection (as might very reasonably be expected) 

 of several instances of mistaken identification of stars of comparison, and 

 some few of numerical error, and has so far resulted in the expurgation 

 and improvement of both catalogues. 



A general list of figured nebulae, with references to the works in which 

 the figures are to be found, and lists of errata and corrections discovered in 

 the various works consulted, concludes the work. 



B 2 



