314 



OBSERVATIONS OF ENCKE S COMET. 



errors are computed from a comparison of the single results in the usual man- 

 ner. The true places of the comet in right ascension and declination have 

 thus been obtained, free from the effect of aberration, parallax, and refraction. 



Date. 



1 



Siderial Time 



at 

 Philadelphia. 



Comet's 



place freed from Aberration, Parallax, and Refraction. 



go 



c 



3 



1842. 



i>- 



o = Comet's true R. A. 



5 = Comet's true Dec. 



March 27 



7" 54"- 57' 



a + 0° 



18'.3.58 ± 0'.06 



a' — r 29".38 ± 1".9 



3 



— 



7 59 21 



6 + 



20 .404 ± .60 



b' + 3 29 .28 ± 2 .3 



3 



28 



7 37 55 



c + 



39.279 ± 0.16 



c' + 7 43 .22 ± 2 .1 



5 



— 



7 50 54 



rf + 



22 .790 ± .03 



d' + 1 20 .91 ± .3 



2 



31 



7 54 35 



f-Q 



7.860 ± 0.12 



/'— 1 46 .13 ± 1 .6 



4 



— 



8 36 34 



5-+1 



56.222 ± 0.65 





3 



April 1 



7 50 51 



/i + 



38.149 ± 0.34 



/j' — 8 .51 ± .4 



3 



5 



8 42 12 



i + 



45 .608 



i' — 11 26 .31 



1 



11 



8 53 36 



k—l 



41 .525 ± 0.19 





4 



— 



8 54 1 



1-2 



29.715 ± 0.28 





4 



By applying the places of the known stars in the above collection, we 

 obtain : 





Siderial Time 



Comet's true Kight Ascension and Decli- 



Correction of 







Date. 



at 











Authority for 





Philadelphia. 



nation from Observation. 



Encke's Ephemeris. 



« 















o 



6 

 Z 



star's place. 



1842. 



ft. 



a 



S 



Cos. 8 A o. 



A 0. 



March 27 



7" 54" 



57' i 1" 46" 29',54 1 + 16 44 56.7 



+ 0'.57 



+ 5".4 



3 



Bessel's Zone. 











1 46 29.64 + 16 45 1.9 



+ 0.67 



+ 10 .6 



3 



Lalande, H. C. 







7 59 



21 



1 46 30.95 + 16 44 54.0 



+ 1.30 



+ .9 



3 



Bessel's Zone. 



28 



7 37 



55 



1 50 5.16; + 16 53 44.9 



+ 2.75 



+ 2 .6 



5 



(' (( 



, 







1 50 4.79 i + 16 53 51.5 



+ 2.40 



+ 9 .3 



5 



Lalande, H. C. 



31 



8 36 



34 



2 1 2 .83 





+ 0.33 





3 



Bessel's Zone. 



, 







2 1 2 .23 





— 0.24 





3 



Piazzi. 



April 11 



8 53 



36 



2 30 16.67 





— 1.85 





4 



Bessel Zones. 





8 54 



1 



2 30 17.40 





— 1 .16 





4 



a a 





Mean of 33 results, cos. 5 A a = 



= + 0^.65 ± 0^32. 









" 19 " A 5 = 



= + 5". 8 ± 1". 2. 







The High School observatory is 5" 0"" 41'.9 west of Greenwich. Latitude 

 N. 39° 57' 8". 



We take occasion to acknowledge, with pleasure, the assistance of Dr. Pat- 

 terson, Messrs. Franklin A. Dick, and John Downes, in making and reducing 

 the observations. 



