lohich have been discovered since July 1844. 411 



the ellipsis deduced by various computers for this interesting 

 comet. 



Faye and Nicolai reckon their longitudes from the mean 

 equinox at the commencement of 1845. Goldschmidt counts 

 from mean equinox of 1844, Sept. 21 '5, and I have referred 

 my node and perihelion to the apparent equinox of Sept. 30. 



The first comet of De Vico was not generally observed after 

 the end of November. With the great equatoreal at Cam- 

 bridge, it was observed until December 7 ; I observed it on 

 December 6 with Mr. Bishop's refractor, and perceived it for 

 the last time on the 30th of December. The comet had a 

 bright nucleus, and, during the month of September, a short 

 fan-like tail. 



Dr. Briinnow of Berlin writes me that he is making a com- 

 plete investigation on the elements of this comet, taking ac- 

 count of the higher powers of the masses in the calculation of 

 planetary perturbations. This is precisely the discussion 

 most desirable for comets of short period, as a basis on which 

 future investigations may be erected. We shall probably 

 learn more respecting the resisting medium brought to light 

 by Encke, after the completion of another revolution of 

 De Vico's comet. 



Great Comet of 1 844-45. 



About the middle of December 1844, a very fine comet be- 

 came visible in the southern hemisphere, in the constellation 

 Grus. It was seen at the Cape of Good Hope on December 

 18; Mr. Caldecott saw it at Trevandrum on December 30; 

 and it was observed by Mr. Taylor at the Madras Observa- 

 tory on January 5. The tail was from 7^ to 10° in length, 

 the nucleus distinct and resembling a star of the fifth magni- 

 tude. On December 28, the tail was found to be slightly 



2 E2 



