138 HISTORY OF ASTROXOMY. 



but well seen with an object-glass of 30 lines aperture, 

 and a magnifying power of 35. Its outline was ill defined, 

 of irregular form, and without tail. 



The above position does not differ much from that 

 which De Vico's comet should have occupied if it had 

 passed its perihelion about five days later than that com- 

 puted by Dr. Briinnow, and M. Goldschmidt concluded 

 that he had obtained an observation of De Vico's comet. 

 But, according to computation, the comet was much 

 nearer the earth on the 1st of August than it was in 

 May, and its position in the heavens was more favorable 

 to its visibility, so that if this comet was really seen in 

 May, it is difficult to understand why it was not some- 

 where seen at a later period. Dr. Briinnow is satisfied 

 that this supposed observation was a mistake, and that 

 De Yico's comet was no where seen in 1855. He ac- 

 counts for this failure to find the comet by the faintness 

 of the object and the uncertainty of the ephemeris, owing 

 to the difficulty of determining the time of perhelion 



Messrs. Laugier and Mauvais, of Paris, computed the 

 orbit of the comet of 1585 from Tycho's and Rothmann's 

 observations, and obtained elements very similar to those 

 of De Vico's comet. They, therefore, concluded* that the 

 comet of De Vico was identical with the comet of 1585, 

 and possibly, also, with those of 1743, 1766 and 1819. 



M. Le Verrier has undertaken, by a computation of the 

 perturbations, to decide whether this comet has been ob- 

 served at any former return to the sun. He concludes 



