202 Royal Society. 



indeed, almost from the first, took his place as one of the best astro- 

 nomers of Europe. In 1810, he was appointed professor of astro- 

 nomy in Konigsberg ; a post which he occupied during the re- 

 mainder of his life, and over which his genius and labours have 

 thrown an imperishable lustre. 



The Observatory of Konigsberg, now so celebrated, owes not only 

 its celebrity, but its existence to Bessel. The building was begun 

 in 1811 under his direction. It was finished in 1813; and the first 

 published observations are dated in November of the same year. 

 From 1815 the observations have been published regularly; accom- 

 panied by full descriptions of the different instruments successively 

 employed, the elements of reduction, some valuable catalogues, and 

 all the information necessary to inspire complete confidence in the 

 results. This publication has exercised a powerful influence on the 

 progress of practical astronomy. 



Bessel's scientific life is one of extraordinary fertility, and it is 

 only a few of the more important of his productions which can even 

 be alluded to in this brief notice. His principal work, the ' Funda- 

 menta Astronomite,' is peculiarly interesting to English astronomers, 

 from the circumstance of its being founded on observations made at 

 the Royal Observatory at Greenwich. Bradley's observations, as is 

 well known, were taken possession of by his representatives, and 

 presented by them to the University of Oxford. From various 

 causes, their publication was not completed until 1805, forty-three 

 years after the death of Bradley ; and although some i-esults and 

 some imperfect catalogues had been deduced from them, the great 

 mass of the observations still remained in a state in which they were 

 nearly useless. At tlie instigation of Olbers, Bessel undertook the 

 formidable task of reducing the whole series. The reduction was 

 commenced in the autumn of 1807, and, though frequently inter- 

 rupted by his otiier avocations and duties, it was nevei' wholly laid 

 aside till its completion in 1818, in which year the ' Fundamenta' 

 made its appearance. Of this great work it would be difficult to 

 speak in terms of too high praise. Besides elaborate determina- 

 tions of all the principal elements of the reduction, — the errors 

 of the instruments, the height of the pole, refraction, parallax, 

 aberration, precession, proper motion, — it contains a catalogue of 

 the niean places of 3222 fixed stars, observed between 17.50 and 

 1762 with the best instruments in existence at that time; and re- 

 duced to the epoch of 1755 with a precision and accuracy of which 

 there was no previous example. It now furnishes astronomers with 

 the best existing means of determining all those data which can 

 only be deduced from a comparison of observations made at consi- 

 derably distant intervals of tiuif', and may be considered, in fact, as 

 having laid the foundations of the principal imp)ovements which 

 have been made in astronomy since the date of its publication. 



The ' Tabulae Ilegiomontanae,' published in 1830, may be re- 

 garded in some respects as a supplement to the ' Fundamenta.' 

 This collection was undertaken with a view to facilitate the reduc- 

 tion of planetaiy observations, past and future, on a uniform system; 



