134 HISTORY OF ASTRONOMY. 



pearance in 1770, was found to be moving in an ellipse, 

 whose period was only five and a half years, and astrono- 

 mers were surprised that it had never been seen before. 

 By tracing back its motion, it was found that at the be- 

 ginning of 1767, it was very near to Jupiter, and the two 

 bodies remained in the neighborhood of each other for 

 several months. Computation, moreover, disclosed the 

 fact that previous to 1767, the elliptic orbit which it de- 

 scribed corresponded not to five, but to fifty years of re- 

 volution round the sun. Again, in 1779, according to 

 Lexell's elements, it was 500 times nearer to Jupiter than 

 to the sun; so that then, notwithstanding the immense 

 size of the sun, its attractive power on the comet was not 

 the 200th part of that exerted by Jupiter. It was found 

 that on the departure of this comet out of the attraction 

 of Jupiter in 1779, its circuit could not be performed in 

 less than twenty years. Thus the action of Jupiter 

 brought the comet of 1770 to us in 1767, and removed it 

 from us in 1779. Moreover, at every revolution, the 

 comet of 1770 ought to come into close proximity to 

 Jupiter, and suffer enormous perturbations, and M. Valz 

 conjectured that the orbit of this comet had been at' last 

 transformed into that of the comet observed in 1843. M. 

 Le Verrier has undertaken a thorough investigation of 

 this question, and he thinks he has demonstrated that 

 the comet of 1770 has nothing in common either with 

 Faye's comet of 1843, or with that discovered by De 

 Vico in 1844, or any other comet whose orbit has been 

 computed. 



