Biela's Comet, 211 



berg, on the 20th of that month, states that a small star near 

 it so enfeebled the comet by its superior light as almost com- 

 pletely to obscure it. The renowned Struve observed it at 

 Dorpat, and on the 7th of November saw it almost centrally 

 cover a star of the ninth magnitude. Later in November, the 

 comet's light became somewhat greater and more condensed. 

 At the Cape of Good Hope it was observed until 1833, January 

 3, by Henderson, who states that its brightness was only 

 nearly the same as that of Encke's comet during part of its 

 preceding apparition. It passed its perihelion on the 28th of 

 November, 1832. 



On its next return, in 1839, it was not seen at all, being 

 too near the sun. But on the succeeding return, in the years 

 1845-6, those remarkable phenomena were seen which have 

 ever since made Biela's so famous amongst comets. In October, 

 1845, Mr. Hind calculated an ephemeris from the elements of 

 Santini, but he failed, notwithstanding great diligence, in being 

 the first to detect the comet. An Italian sky again gave the 

 priority to the observers at Rome, where it was seen by De 

 Vico on the 26th of November ; and on the 28th, Dr. Galle, 

 at Berlin (the same astronomer who the year after was the first 

 to see Neptune with the knowledge of its planetary character), 

 also succeeded in perceiving it, close to the calculated place. It 

 resembled an excessively faint nebula, and not till the evening 

 of the 29th of November, when it was found to have moved 

 according to the ephemeris, did the Berlin astronomers feel 

 convinced that it was actually the expected comet. Encke 

 himself declared that he should not have seen it had it not 

 been pointed out to him, and for several nights he had to 

 assure himself of its existence. Professor Challis observed it 

 with the Northumberland telescope at Cambridge, on the 1st 

 and 3rd of December. 



On the 27th of January, 1846, Mr. Airy wrote to the Editor 

 of the Astronomische Nachrichten — " Professor Challis has 

 found, and the observation has been confirmed by Mr. Hind, 

 that Biela's comet is double. Since I received notice of this, 

 the weather has been excessively bad. It is evidently a thing 

 which deserves the utmost attention of astronomers/'* On 

 the 29th of the same month, Encke wrote thus to the same 

 periodical: "Biela's comet offers so remarkable a figure that 

 I cannot help calling attention to it. Immediately on look- 

 ing for it with the smaller 3 £ -feet Dollond, d' Arrest found 

 that the comet consisted of two completely separated cometary 

 nuclei. This was on the 27th of January. In the refractor it 

 appeared the same. The fainter nucleus is to the north of the 

 other. There is in both a trace of a tail, its direction being 

 * Ast. Nach., No. 553. 



