PHYSICAL ASTRONOMY. 



a very remarkable verification of the theory of 

 Gravity, and the calculation of Disturbing Forces. 



This Comet may be expected again about the year 

 1835. The investigations of LA PLACE will ren- 

 der it much easier to calculate the quantity by 

 which its arrival may be anticipated or retarded 

 by the action of the planets. 



A Comet, which was observed in 1770, had a mo- 

 tion, when carefully examined, which could not 

 be reconciled with a parabolic orbit, but which 

 might be represented by an elliptic orbit of mo- 

 derate eccentricity, in which it revolved in the 

 space of five years and eight months. This Co- 

 met, however, had never been seen in any former 

 revolution, nor has it been seen in any subsequent 

 one. 



280. Mr BURKHARDT, on tracing the path of 

 this Comet, found that between the years 1767 

 and 1770, it had been very near to Jupiter, and 

 again had come very near to that planet in 

 1779 ; he therefore conjectured, that the dis- 

 turbance of Jupiter might have so altered its 

 original orbit, as to render the Comet for a 

 time visible from the Earth ; and may have so 

 changed it again, after one revolution, as to re- 

 store the Comet to the same region in which it 

 had formerly moved. This conjecture has been 

 confirmed by a careful application of the for- 

 mulas of the Mecanique Celeste. 



Mr 



