62 Imperial Institute of France. 



glasses. Obliged to have recourse to his colleagues, M.Burck- 

 hardt received from M. Bouvard such observations as 

 the limited time would permit him to make. As soon as 

 he had a sufficient number (this may be three, only provid- 

 ins: they are neither too near nor too distant from each 

 other) M. Burckhardt calculated the orbit. The smallncss 

 of the arc and the uncertainty of the observations rendered 

 this labour very troublesome. Nevertheless this first ap- 

 proximation w/as sufficient to announce that the comet 

 would soon disappear, because it proceeded to lose itself in 

 the rays of the sun, i.e. to rise and set almost at the same 

 time with the sun. M. Burckhardt also announced that 

 the comet would re-appear about the middle of August ; 

 tliat it would then be nearly at the same distance from the 

 earth, but twice as much nearer tl\e siin, and that in this 

 way its light would be quadrupled: that on the 13lhof 

 August it ought to rise an hour and a half before the sun; 

 that on the 1 5th of September, the day of the perihelion 

 passage, it would be so near the sun as to set no longer; 

 that from this epoch it ought to augment in size and lustre 

 for about a month, because it would then approach the 

 earth ; that it would afterwards gradually hecome feeble, 

 but that we might follow it with glasses to the month of Ja- 

 nuary, perhaps even a little longer : lastly, that the distance 

 of the comet from the earth would be always considerably 

 greater than that from the earth to the sun. These pre- 

 dictions, which were coiifirmed by the event, excited no 

 sensation because they came too soon. M. Olbers, a di- 

 stinguished astronomer, one of the deputies from Bremen, 

 at the baptism of the King of Rome, carried with him from 

 Paris the elements calculated by M. Burckhardt. M. Ger- 

 gone of Nismes made use of them for constructing an 

 ephemerides of the course of the comet from February 

 1811 to the end of March 1812. This labour, which was 

 merely an object of curiosity, as long as the comet by its 

 brilliancy attracted all eyes towards it, became a matter of 

 utility when it v/as necessary to use telescopes to view it. 



Astronomers nevertheless, after having determined so 

 long beforehand every thing which they thought pro- 

 per for interesting the public, contiimed to observe the 

 comet in silence, and to compare their observations with 

 calculation, in order to rectify the trifling but inevilable 

 errors in the first attempt at finding an orbit. M. de 

 Flau<'ercues, who first saw the comet, calculated all his ob- 

 servjitions. After having by himself determined the ele- 

 ments of the orbit, he thought he discovered some resem- 

 blance 



