Biela' s Comet. 209 



elevation above the horizon, appeared to the naked eye as a 

 roundish, luminous, nebulous mass, nearly as large as the 

 moon, and without any tail. 



When the orbit of the comet was calculated, it was found 

 that its elements were not very different from those of one dis- 

 covered by Montaigne, in the year 1772. But more accurate in- 

 vestigations, made by Bessel and Gauss, on the supposition 

 of an elliptic orbit, showed that the conjecture that the two 

 comets were identical, was at least a very doubtful one. But, 

 as Montaigne's comet had been very imperfectly observed (it 

 was visible only for a very short time), Gauss remained of 

 opinion that they were in fact one comet, with a period of 

 about five years; though Bessel, on the other hand, was 

 unable to assent to this. 



We now come to the time when this remarkable comet 

 acquired the name by which it has since been known. On the 

 evening of the 27th of February, 1826, Biela, at Josephstadt, 

 in Bohemia, discovered a comet which then appeared as a 

 small round nebula, with a very fine point of light in the 

 centre. Other astronomers afterwards observed it, of whom 

 Gambert was the second, who independently discovered it at 

 Marseilles, and says, " It has neither tail nor nucleus, but 

 appears like a feeble nebulosity, the light of which is a little 

 more intense towards the centre. "* This was on the 9th of 

 March. Harding observed it at Gottingen, having heard of it 

 from Biela, and on the 14th of March perceived a small tail. 

 The comet was in perihelion on the 18th of that month. At 

 no time during this or any subsequent appearance was it 

 visible to the naked eye ; and it ceased on this occasion to be 

 perceptible to the telescopes in the month of May. Biela him- 

 selff was the first who arrived at the conclusion, which all the 

 calculators afterwards confirmed, that the comet had a period of 

 about six and a half years, and was identical with that of 1805. 

 He, indeed, suspected also that it might be the same as those 

 seen in the years 1772, 1779, and 1812; but the latter two sup- 

 positions proved to be not tenable, and the former one continues, 

 as we have already hinted, only a probability, whilst the identity 

 of the comet discovered by Pons, in 1805, w T ith this of Biela is 

 an unquestionable fact. Thus, for the fourth time, was a 

 comet's period of revolution round the sun satisfactorily de- 

 termined, the three preceeding cases being those of the comets 

 of Halley, Olbers, and Encke, whose periods are respectively 

 70, 74, and only o\ years. 



* Astronomische NachricJUen, No. 02. 



t He informed Schumacher that he had in fact partly expected it. Biela had 

 already a cometic reputation, and had independently discovered a comet the 

 previous summer, although on that occasion he was anticipated by Pons. 



VOL. XI. — NO. III. p 



