234 ASTRONOMICAL' OBSERVATIONS, 



as to occasion an error of more than 5 or 6 seconds. — My eye 

 was directed to the precise spot where the eclipse began, which 

 was observed at 6 h 45' 48" mean time, or 6 h 43' 26" appa- 

 rent time. 



The beginning of this eclipse was observed by Mr. Patterson 

 in Philadelphia, at 6 h 47' 40^" apparent time. 



The longitude of Lancaster by the above eclipse appears to 

 be 5" 4' 19" west from Greenwich, which is 47" less than I 

 have stated it from the result of a considerable number of the 

 eclipses of Jupiter's satellites, and some lunar distances. — The 

 longitude of the city of Philadelphia, by the same eclipse as 

 observed by Mr. Patterson, appears to be 4 h 59' 33" west from 

 Greenwich; which is about 1' 4" less than it has been settled 

 by a great number of corresponding observations made there, 

 and at the royal observatory of Greenwich. This difference, 

 no doubt principally arises from the imperfection of the lunar 

 theory, and probably much the greater part of it from the er- 

 rors in the moon's latitude. 



July 4th. Emersion of the 2d satellite of Jupiter observed 

 at 8 h 55* 4" mean time, night clear. 



10/ h. Emersion of the 1st satellite of Jupiter observed at 

 S h 9' 0" mean time, twihglit very strong. 



1 Ith. Emersion of the 2d satellite of Jupiter observed at 

 ll h 29' 38" mean time, niglu clear. 



17 tli. Emersion of the 1st satellite of Jupiter observed at 

 10' 1 4' 16" mean time, night clear. 



26th. Emersion of the 3d' satellite of Jupiter observed at 

 8 22' 39" mean time, txmlight very strong. 



August 2d. Emersion of the 1st satellite of Jupiter observed 

 at 8 h 23' 9" mean time, twilight very strong. 



2d. Immersion of the 3d satellite of Jupiter observed at 

 10'' 5' 5" mean time, night clear. 



9th. Emersion of the 1st satellite of Jupiter observed at 

 10' 1 18' 20" meantime, a little hazy. 



September 6th. Emersion of the 2d satellite of Jupiter ob- 

 served at 8 h 18' 9" mean time, very clear, but the planet tre- 

 mulous. 



* The person who noted the time, had some doubts whether this should not be 54'. 



