556 COSMOS. 



From the summary here given, it follows that since the dis- 

 covery of Encke's Comet 31 as an interior one in the year 1819, 

 up to the discovery of the interior comet of D' Arrest, scarcely 



31 The short period of revolution of 1204 days was dis- 

 covered by Encke on the reappearance of his comet in the 

 year 1819. See the first calculated elliptical orbits in the 

 ^Berliner. Astron. Jahrbuch, for 1822, p. 193, and for the 

 constants of the resisting medium assumed to explain the 

 accelerated revolution. Encke's Vierte AbJiandlburg in the 

 ScJiriften der Berl. Akademie for the year 1844. (Compare 

 Arago, in the Annuaire for 1832, p. 181: in the Lettre a M. 

 Alexandra de Humboldt, 1840, p. 12; and Galle, in Gibers' 

 Cometenbolinen, p. 221.) As belonging to the history of 

 TUncktfs Comet, it must here be called to mind that so far as 

 our knowledge of the observations extends, it was first seen 

 upon two days by Mechain on the 17th of January, 1786; 

 then by Miss Carolina Herschel from the 7th to the 27th of 

 November, 1795 ; afterwards by Bouvard, Pons, and Huth, 

 from the 20th of October to the 19th of November, 1805; 

 finally, as the tenth reappearance since Mechain's discovery in 

 the year 1786, by Pons from the 25th of November, 1818, to 

 the 12th of January, 1819. The first reappearance calculated 

 beforehand by Encke, was observed by Riimker at Paramatta. 

 (Galle, op. cit. pp. 215, 217, 221, and 222.) Biela's interior 

 comet, or as it is also called, Biela's and Gambart's, was first 

 seen by Montaigne on the 8th of March, 1772 ; then by Pons 

 on the 10th of November, 1805; afterwards on the 27th of 

 February, 1826, at Josephstadt in Bohemia, by Von Biela; and 

 on the 9th of March by Gambart, at Marseilles. The earliest 

 rediscoverer of the comet of 1 772 is undoubtedly Biela, and not 

 Gambart ; but on the other hand, he calculated the elliptical 

 elements of its orbit earlier than Biela, and nearly at the 

 same time as Clausen. (Arago, in the Annuaire of 1832, 

 p. 184 ; and in the Comptes Rendus, torn, iii. 1836, p. 415.) The 

 first re-appearance of Biela's Comet, calculated beforehand, 

 was observed by Henderson, at the Cape of Good Hope, in 

 October and December, 1832. The already mentioned won- 

 derful doubling of Biela's Comet by separation, took place at 

 its llth reappearance since 1772, at the end of the year 1845. 

 (See Galle, by Olbers, pp. 214, 218, 224, 227, and 232.) 



