Notice of the Periodical Comet of 1819. 273 



has any influence on raising the prices, the want of labour, 

 industry, and of produce, must cause it also. 



These considerations point out in the strongest manner the 

 poverty of this royal people, of whom two-thirds, if not three- 

 fourths, were reduced to live on fish and cheese, and drink 

 piquette, when the expence of the table of Vitellius amounted, 

 in a single year, to 175 millions of francs. 



Art. XII. — Account of the Periodical Comet of 1819 that 

 revolves within the orbit of Jupiter with a period of SI 

 years, * 



Till lately there had been but one comet whose return to its 

 perihelion has been observed, and whose periodical time is 

 known. This is the comet of 1682, which occupies about 

 seventy-six years in performing its whole revolution. Halley 

 ^discovered it to be the same with one which had already been 

 observed, at two other epochs, in 1531 and 1607, and he pre- 

 dicted its return in 1758 or 1759. At this latter epoch, and 

 before the comet had become visible, Clairaut calculated the 

 instant of its passing its perihelion, having regard to the dis- 

 turbances in its elliptical motion. The result of that immense 

 labour differs only a few days, as is well known, from the time 

 of the observed passage, which took place on the 12th of 

 March 1759. This remarkable phenomenon of the re-ap- 

 pearance of a comet at its perihelion, after one or more revo- 

 lutions, has also occurred in our time with respect to the co- 

 met discovered in 1818 by M. Pons, who at that time ob- 

 served it at Marseilles. The comparison of its parabolic ele- 

 ments with those of a comet observed in 1805 leads to the sus- 

 picion that the two bodies are the same. The remark was 

 made at the Bureau des Longitudes, by M. Arago, when the 

 discovery of the new comet was there announced ; it was also 

 made in Germany by M. Olbers, who thought, moreover, that 

 this comet must be the same with that which had been observ- 



• This Article is composed of part of the Report of MM, Laplace, Le- 

 geudre, and Poisson, upon M, Damoiseau's Memoir on this comet, and 

 part of the Memoir itself 



