310 Life, Reseaixhes, and Discoveries of F. W. Bessel 



tion. In the reduction of these observations, however, his final 

 improvement, which does away altogether with the necessity of 

 using special tables for the several uranographical corrections, 

 and for individual stars, and renders it practicable, by the calcula- 

 tion of a system of constants for each star, and an annual table 

 common to all the stars, to provide for the reduction of all merid- 

 ional observations, was not yet adopted. That capital step, 

 which has so infinitely facilitated all subsequent reductions, was 

 not made till somewhat later, and had nearly been anticipated by 

 Mr. Baily, who, on his part, and independently, had been occu- 

 pied about the same time on a sim.lar simplification* In fur- 

 therance of the important object of facilitating the reduction of 

 observations of the planets, as well as of the fixed stars, on a 

 uniform system, he prepared and published, in 1830, his Tabula 

 Regiomontattce, a work of the greatest utility and influence on 

 the practice of astronomers in this respect. 



The principal instruments at first supplied to the Konigsberg 

 Observatory were two, a transit by Dollond, and a meridian circle 

 by Cary. This last instrument, though not itself of a very high 

 order of excellence, may be considered as having been rendered 

 so by the masterly and elaborate investigation of its errors of di- 

 vision which Bessel bestowed upon it. The complete investiga- 

 tion of instrumental error was a subject on which he was at 

 every period remarkably scrupulous, and not without reason, as 

 the dreadful consequences which have followed its neglect in 

 more than one instance clearly demonstrate. In his opinion, the 

 reputation of no artist, however distinguished, could be held to 

 dispense with the most careful and searching scrutiny into the 

 errors of his workmanship; or, with the most refined application, 

 both of experience and theory, into the amount and laws of its 

 flexure, whether of the telescope or limb, by its own weight in 

 different positions. In fact, no astronomer has ever gone deeper 

 into the theory of instruments, or exemplified that theory by 

 more elaborate experimental inquiries. The finishing hand was 

 put to a most remarkable memoir on the effects of flexure, but 

 a very short time previous to his death, which has only just seen 

 the light (see Astronomische Nachrichtcn, No. 577, et seq.), & 

 publication having been directed in his will. 

 : The improvement of Carlini's tables of the sun was the ob- 

 ject and result of the first five years' observations with Cary > 

 circle and Dollond's transit ; though other objects of m tereSt f 

 jvere not neglected,' especially that of an exact determination oi 

 the places of those stars in which large proper motions had been 

 remarked. But when in the year 1820, the circle of Cary ^ 



* See the Memoir of Mr. Baily, Mem. Jlstron. Soc, vol. iv, p. 324, where, 



lme 7, lor " precession" ™n<l n U i» ' 



in 





