182 Astronomical and Nautical Collections. 



§ 39. 

 Such, therefore, is the proportion of the curtate distances of 

 the comet from the earth in the first and third observations. 

 In order to find the distances themselves, we must determine 

 from them the chord and the twro extreme distances AC, SA, 

 SC, § 34, and, compare the area of the sector with the time 

 intervening. Now the two distances oftlie earth from the sun, 

 S a, So, being R' and R' ', and the distances of the comet 

 from the sun, SA, SC, ;' and r'", we have r'' = R' — 2 R' 5' 

 cos (A'— a') + ?'' sec'^jS; and r"'^= R'"" — 2R'" M f ' cos 

 t^\"'-cc"')+M'^"sec'ff". 



[To be continued,'] 



V. Further Remarks on the Transit of the Comet of 1819 over 

 the Sun. By Dr. Olbeks.— Dope's Jahrb., 1823. 

 The authority of the observation of General Von Lindener, 

 ia favour of the invisibility of the comet in its transit, is con- 

 siderably diminished by the testimony of other observers, par- 

 ticularly Professor Schumacher and Professor Brandes, who 

 agree in declaring, that the sun was by no means free from spots 

 on the day of the transit, as it appeared to General Von Lin- 

 dener ; and on the other hand, Dr. Gruithuisen and Professor 

 Wildt agree in describing a small spot near the middle of the 

 sun's disc, which might possibly have been the comet, though 

 certainly not so distinctly defined as a planet would have 

 been. 



vi. Errors of the Tables of the Planets, with other Notes, 

 from BopE and Zacii. 

 The German observations of Jupiter and Saturn, as recorded 

 by Bode, do not agree c|uite well enough to settle the question 

 of the accuracy of the tables of their motions, without a re- 

 ference to the Greenwich Observations. They appear, however, 

 to prove, that Bouvard's tables of both planets are considerably 

 more accurate than Delambre's, The mean error of Bouvard 

 in the H. longitude of 11, about the; time of opposition in 1819, 



