Prof, Fisher on the Orbit of the Comet of 1819. 315 

 True time of passing the ecliptic. June 25ih. 11'' 59'" 18' 



Sun's apparent longitude, - . - 93** 31' 40''i. 



Log. earth's distance from sun, - . .0070501 



Log. dist. comet from sun, . - - 4.5355761 

 Log. Hor. motion in min. round the sun, - 1.3-1079 1"! 



Obliquity of the motion to the line of common section of the 



orbit and ecliptic, 



83° 38' 5B' 



1.S381170 



Log. Hor. motion reduced to a perpendicular to the line of 

 common section, .... 



F 



Hor, motion as seen from the earth, - • 8'.7309 

 Hor. motion of earth about the sun, - - 2'.3847 



l)o. about tlie comet, 



3'. 58808 



Obliquity of the apparent orbit to the ecliptic, 7if° 36' 17^ E. 

 Angle of apparent path with a secondary of the ecliptic pass 

 ing through the sun's centre, - 88° 51' 3rW 





DifiT. of heliocentric long, of comet and earth, 1' 17^ 



True elongation of comet from O, - 0.64689 E. 



Effect of aberration, .... 



.§1463 



Apparent elongation at time of 6 , - - 0.43537 



V 



Effect of aberration on time of ^^ , - - +5™ ^4' 



Sun's semidiameter— Irradiation 3^.3, - - 45' 42M 



Half duration of transit, - - - 109^809 



Mean time of apparent beginning, June 2jth, 10'" 15'^ 20* 



Do. of end, 



13 53 41) 



The transit of a comet over the sun's disc is a phenomenon of 

 rare occurrence. Lalande remarks that it had never been observ- 

 ed at the time he wrote. From a statement, however, in the 

 Journal de Physique, (Feb. 1798,) it appears probable that a body, 



