GENERAL PLAN OF ELLIPTIC COMETS. 



brought them to the epoch of 1779. On comparing- the orbits 

 thus determined with those of the table of possible orbits of 

 LcxelPs comet, he has shown that none of them can be identical 

 with it, however strongly some of the elements of their present 

 orbits may raise such a presumption. 



43. The comet of De Yico having presented striking analogies 

 with a comet which was observed by Tycho Brahe and Hoth- 

 mann in 1585, and one observed by La Hire in 1678, M. Le 

 Verrier has applied like principles to the investigation of these 

 questions. 



MM. Laugier and Mauvais observed that the elements of De 

 Vico's comet presented such a resemblance to that of Tycho Brahe, 

 as almost to decide the question of their identity. M. Le Terrier 

 tracing back the comet of De Vico to 1585, has shown that its 

 orbit at that epoch was so different from that of the comet of 

 Tycho, as to be incompatible with any plausible inference of their 

 identity.* 



He has shown, however, by like reasoning, that there is a high 

 degree of probability that the comet of De Vico is identical with 

 that observed by La Hire in 1678. 



44. M. Blainplan discovered a comet at Marseilles on the 28th 

 November, 1819, which was observed at Milan until 25th 

 January, 1820. The observations reduced and calculated by 

 Prof. Encke gave an elliptic orbit with a period a little short of 

 five years. Clausen conjectures'that this comet may be identical 

 with that of 1743. It has not been seen since 1820. 



45. A comet was discovered by M. Pons on June 12th, 1819, 

 which was observed until July 19th. Prof. Encke assigned to it 

 an elliptic orbit, with a period of 5^ years. 



46. A comet, discovered by Mr. Pigott at New York in 1783, 

 was shown by Burckhardt to have an elliptic orbit, with a period 

 of 5 1 years. 



47. On the 26th June, 1846, a comet was discovered at Naples 

 by M. Peters, which was subsequently observed at Rome by De 

 Yico, and continued to be seen until 21st July. An elliptic orbit 

 is assigned to this comet, with a period of from thirteen to sixteen 

 years, some uncertainty attending the observations. The re- 

 appearance of this comet may be expected in 1859, 1860. 



48. A synoptical Table, showing the elements of the elliptic 

 comets above described, may be seen by a reference to my 

 " Hand-Book of Astronomy." 



49. In fig. 2 (page 172), the orbits of these thirteen comets 

 brought to a common plane, are represented roughly but in their 



* Mem. Acad. des Sciences, 1847. 



171 



